Cancer Letters - Articles in Press

Kindlin-2 controls sensitivity of prostate cancer cells to cisplatin-induced cell death - Corrected Proof

2010-09-02

Abstract: Resistance to anticancer drugs is often observed in prostate cancer therapy. Kindlin-2 was recently found overexpressed during cancer progression. In this study, we examined the functional role of Kindlin-2 in cisplatin-induced prostate cancer cell death. Kindlin-2 was highly expressed in the androgen-insensitive (PC-3 and DU-145), but not in the androgen-sensitive cell lines (e.g., LNCaP). Overexpression of Kindlin-2 in LNCaP protected the cells from cisplatin-induced death, while Kindlin-2 knock-down in PC-3 cells enhanced cisplatin sensitivity. Mechanistically, Kindlin-2 regulation of the anti-apoptotic Bcl-xL may explain the increased cell death in the absence of Kindlin-2. Taken together, Kindlin-2 appears to play a functional role in prostate cancer cell sensitivity to cisplatin. Targeting Kindlin-2 may therefore improve drug efficacy and reduce drug doses, and would likely be beneficial for the treatment of prostate cancer.

Viral hit and run-oncogenesis: Genetic and epigenetic scenarios - Corrected Proof

Hans Helmut Niller, Hans Wolf, Janos Minarovits — 2010-09-02

Abstract: It is well documented that viral genomes either inserted into the cellular DNA or coreplicating with it in episomal form can be lost from neoplastic cells. Therefore, “hit and run”-mechanisms have been a topic of longstanding interest in tumor virology. The basic idea is that the transient acquisition of a complete or incomplete viral genome may be sufficient to induce malignant conversion of host cells in vivo, resulting in neoplastic development. After eliciting a heritable change in the gene expression pattern of the host cell (initiation), the genomes of tumor viruses may be completely lost, i.e. in a hit and run-scenario they are not necessary for the maintenance of the malignant state. The expression of viral oncoproteins and RNAs may interfere not only with regulators of cell proliferation, but also with DNA repair mechanisms. DNA recombinogenic activities induced by tumor viruses or activated by other mechanisms may contribute to the secondary loss of viral genomes from neoplastic cells. Viral oncoproteins can also cause epigenetic dysregulation, thereby reprogramming cellular gene expression in a heritable manner. Thus, we expect that epigenetic scenarios of viral hit and run-tumorigenesis may facilitate new, innovative experiments and clinical studies in spite of the fact that the regular presence of a suspected human tumor virus in an early phase of neoplastic development and its subsequent regular loss have not been demonstrated yet. We propose that virus-specific “epigenetic signatures”, i.e. alterations of the host cell epigenome, especially altered DNA methylation patterns, may help to identify viral hit and run-oncogenic events, even after the complete loss of tumor viruses from neoplastic cells.

Nuclear Factor-κB modulates cellular glutathione and prevents oxidative stress in cancer cells - Corrected Proof

Qinghang Meng, Zhimin Peng, Liang Chen, Jutong Si, Zhongyun Dong, Ying Xia — 2010-09-01

Abstract: The NF-κB is best known for its role in inflammation. Here we show that constitutive NF-κB activity in cancer cells promotes the biosynthesis of redox scavenger glutathione (GSH), which in turn confers resistance to oxidative stress. Inhibition of NF-κB significantly decreases GSH in several lines of human leukemia and prostate cancer cells possessing high or moderate NF-κB activities. Concomitantly, NF-κB inhibition by pharmacological and molecular means sensitizes “NF-κB positive” cancer cells to chemically-induced oxidative stress and death. We propose that inhibition of NF-κB can reduce intracellular GSH in “NF-κB-positive” cancers thereby improving the efficacy of oxidative stress-based anti-cancer therapy.

Phospholipase D-mTOR requirement for the Warburg effect in human cancer cells - Corrected Proof

2010-09-01

Abstract: A characteristic of cancer cells is the generation of lactate from glucose in spite of adequate oxygen for oxidative phosphorylation. This property – known as the “Warburg effect” or aerobic glycolysis – contrasts with anaerobic glycolysis, which is triggered in hypoxic normal cells. The Warburg effect is thought to provide a means for cancer cells to survive under conditions where oxygen is limited and to generate metabolites necessary for cell growth. The shift from oxidative phosphorylation to glycolysis in response to hypoxia is mediated by the production of hypoxia-inducible factor (HIF) – a transcription factor family that stimulates the expression of proteins involved in glucose uptake and glycolysis. We reported previously that elevated phospholipase D (PLD) activity in renal and breast cancer cells is required for the expression of the α subunits of HIF1 and HIF2. We report here that the aerobic glycolysis observed in human breast and renal cancer cells is dependent on the elevated PLD activity. Intriguingly, the effect of PLD on the Warburg phenotype was dependent on the mammalian target of rapamycin complex 1 (mTORC1) in the breast cancer cells and on mTORC2 in the renal cancer cells. These data indicate that elevated PLD-mTOR signaling, which is common in human cancer cells, is critical for the metabolic shift to aerobic glycolysis.

MicroRNA expression and its implication for the diagnosis and therapeutic strategies of gastric cancer - Corrected Proof

Jianbo Wang, Qingwei Wang, Hong Liu, Bo Hu, Wei Zhou, Yufeng Cheng — 2010-08-27

Abstract: MicroRNAs (miRNAs) are a recently discovered category of small RNA molecules that regulate gene expression at the post-transcriptional level. Accumulating evidence indicated that miRNAs are aberrantly expressed in a variety of human cancers and crucial to tumorigenesis. We herein provide a brief review of miRNA biogenesis, function, deregulation and their possible role as oncogenes or tumor suppressors in the pathogenesis of gastric cancer. The role of miRNAs in the carcinogenic effect of Helicobacter pylori infection was also discussed. Finally, we comment on the potential role of miRNAs in improving the current management of gastric cancer.

Targeting ER stress induced apoptosis and inflammation in cancer - Corrected Proof

Tom Verfaillie, Abhishek D. Garg, Patrizia Agostinis — 2010-08-23

Abstract: Disturbance in the folding capacity of the endoplasmic reticulum (ER), caused by a variety of endogenous and exogenous insults, prompts a cellular stress condition known as ER stress. ER stress is initially shaped to re-establish ER homeostasis through the activation of an integrated intracellular signal transduction pathway termed as unfolded protein response (UPR). However, when ER stress is too severe or prolonged, the pro-survival function of the UPR turns into a toxic signal, which is predominantly executed by mitochondrial apoptosis. Moreover, accumulating evidence implicates ER stress pathways in the activation of various ‘classical’ inflammatory processes in and around the tumour microenvironment. In fact, ER stress pathways evoked by certain conventional or experimental anticancer modalities have been found to promote anti-tumour immunity by enhancing immunogenicity of dying cancer cells. Thus, the ER functions as an essential sensing organelle capable of coordinating stress pathways crucially involved in maintaining the cross-talk between the cancer cell’s intracellular and extracellular environment. In this review we discuss the emerging link between ER stress, cell fate decisions and immunomodulation and the potential therapeutic benefit of targeting this multifaceted signaling pathway in anticancer therapy.

MicroRNA-10b induced by Epstein-Barr virus-encoded latent membrane protein-1 promotes the metastasis of human nasopharyngeal carcinoma cells - Corrected Proof

2010-08-23

Abstract: MicroRNA-10b (miR-10b) has been reported to facilitate the metastasis of breast cancer. However, little is known about the role of miR-10b in the metastasis of nasopharyngeal carcinoma (NPC). Here, we show that high levels of miR-10b expression in Epstein-Barr virus (EBV)-positive latent membrane protein-1 (LMP1)-expressing NPC cells, and its expression is down-regulated by silencing LMP1 or Twist. Induction of miR-10b over-expression in LMP1-silent C666-1 cells promoted significant wound healing and transmembrane invasiveness in vitro. More importantly, miR-10b over-expression promoted the metastasis of NPC and accelerated the death of tumor-bearing nude mice. These findings strongly suggest that miR-10b positively regulates the metastasis of NPC.

Non-founder BRCA1 mutations in Russian breast cancer patients - Corrected Proof

2010-08-20

Abstract: A few founder BRCA1 mutations (5382insC, 4154delA, 185delAG) account for up to 15% of high-risk (young-onset or familial or bilateral) breast cancer (BC) cases in Russia. The impact of non-founder BRCA1 mutations in this country is less studied; in particular, there are no reports analyzing gross rearrangements of this gene in the Russian patient series. We selected for the study 95 founder mutation negative high-risk BC cases. Combination of high-resolution melting (HRM) and sequencing revealed six presumably BC-associated alleles (2080delA, 4808C>G, 5214C>T, 5236G>A, 5460G>T, 5622C>T) and one variant of an unknown significance (4885G>A). The pathogenic role of the 5236G>A mutation leading to G1706E substitution was further confirmed by the loss of heterozygosity analysis of the corresponding tumor tissue. Multiplex ligation-dependent probe amplification (MLPA) revealed two additional BRCA1 heterozygotes, which carried BRCA1 deletions involving exons 1–2 and 3–7, respectively. Based on the results of this investigation and the review of prior Russian studies, three BRCA1 mutations (2080delA, 3819del5, 3875del4) were considered with respect to their possible founder effect and tested in the additional series of 210 high-risk BC patients; two BRCA heterozygotes (2080delA and 3819del5) were revealed. We conclude that the non-founder mutations constitute the minority of BRCA1 defects in Russia.

RAD001 shows activity against gastric cancer cells and overcomes 5-FU resistance by downregulating thymidylate synthase - Corrected Proof

2010-08-20

Abstract: We evaluated RAD001, an inhibitor of the mammalian target of rapamycin (mTOR) in human gastric cancer cell lines and determined the molecular mechanisms. RAD001 has marked growth inhibitory activity against the SNU-1 and SNU-216 cells. It inhibited phosphorylation of mTOR and S6K, and induced G1 cell cycle arrest. Synergistic growth-inhibitory effects in combination with 5-fluorouracil (5-FU) was identified. Furthermore, RAD001 conferred sensitivity to 5-FU-resistant cell lines by downregulating thymidylate synthase (TS). In conclusion, RAD001 showed growth inhibitory activity against gastric cancer cells and acted synergistically with cytotoxic agents such as 5-FU by downregulating TS.

Vasoactive intestinal peptide (VIP) induces malignant transformation of the human prostate epithelial cell line RWPE-1 - Corrected Proof

2010-08-16

Abstract: The carcinogenic potential of vasoactive intestinal peptide (VIP) was analyzed in non-tumor human prostate epithelial cells (RWPE-1) and in vivo xenografts. VIP induced morphological changes and a migratory phenotype consistent with stimulation of expression/activity of metalloproteinases MMP-2 and MMP-9, decreased E-cadherin-mediated cell–cell adhesion, and increased cell motility. VIP increased cyclin D1 expression and cell proliferation that was blocked after VPAC1-receptor siRNA transfection. Similar effects were seen in RWPE-1 tumors developed by subcutaneous injection of VIP-treated cells in athymic nude mice. VIP acts as a cytokine in RWPE-1 cell transformation conceivably through epithelial–mesenchymal transition (EMT), reinforcing VIP role in prostate tumorigenesis.

Tumor microenvironment modifications induced by soluble VEGF receptor expression in a rat liver metastasis model - Corrected Proof

2010-08-11

Abstract: Vascular endothelial growth factor is a potent pro-angiogenic growth factor which is also known to alter tumor microenvironment by inhibiting dendritic cell differentiation and promoting accumulation of myeloid-derived suppressor cells. In the present study, we analyzed the modifications induced by intratumoral expression of sFLT-1, a soluble VEGF receptor, in a rat metastatic colon carcinoma model. We generated colon cancer cell lines stably expressing sFLT-1 or a mock construct. Human umbilical vein endothelial cells cultured with conditioned medium from sFLT-1-expressing tumor cells exhibit a significantly decreased survival, demonstrating the functionality of the secreted sFLT-1. In vivo, sFLT-1 expression induced a 30% decrease in microvessel density in 15-day old experimental liver metastasis from colon carcinoma. Tumor growth was inhibited by 63% and 52% in left and right liver lobes respectively within 25days. In these tumors, sFLT-1 expression was associated with a decreased myeloid cell infiltration and a modification in the expression of several cytokines/chemokines. Altogether, these results suggest that VEGF trapping by sFLT-1 intratumoral expression results in reduced vascularization, tumor growth inhibition and modification of immune tumor microenvironment.

Helicobacter pylori in the pathogenesis of gastric cancer and gastric lymphoma - Corrected Proof

Sung Soo Kim, Victoria E. Ruiz, Jaqueline D. Carroll, Steven F. Moss — 2010-08-09

Abstract: Chronic gastric infection by the gram-negative bacterium Helicobacter pylori is strongly associated with the development of distal gastric carcinoma and gastric mucosal lymphoma in humans. Eradication of H. pylori with combination antibiotic therapy cures most cases of gastric lymphoma and slows progression to gastric adenocarcinoma. H. pylori promotes gastric neoplasia, principally via the induction of an intense gastric inflammatory response that lasts over decades. This persistent inflammatory state produces chronic oxidative stress and adaptive changes in gastric epithelial and immune cell pathobiology that in a minority of infected subjects eventually proceeds to frank neoplastic transformation.

Bacteriophage hyaluronidase effectively inhibits growth, migration and invasion by disrupting hyaluronan-mediated Erk1/2 activation and RhoA expression in human breast carcinoma cells - Corrected Proof

2010-08-05

Abstract: Aberrant hyaluronan production has been implicated in many types of tumor. In this context, hyaluronidase has been explored as a viable therapeutic approach to reduce tumoral hyaluronan. However, elevated levels of hyaluronan in tumors are often associated with high expression levels of cellular hyaluronidases, which consequently produce various sizes of saturated hyaluronan fragments with divergent pro-tumoral activities. The current study shows that different hyaluronan metabolisms of mammalian and microbial hyaluronidases could elicit distinct alterations in cancer cell behavior. Unlike saturated hyaluronan metabolites, unsaturated hyaluronan oligosaccharides produced by bacteriophage hyaluronidase, HylP, had no biological effect on growth of breast carcinoma cells. More importantly, HylP’s metabolic process of hyaluronan into non-detrimental oligosaccharides significantly decreased breast cancer cell proliferation, migration and invasion by disrupting Erk1/2 activation and RhoA expression. Our results suggest that it may be possible to exploit HylP’s unique enzymatic activity in suppressing hyaluronan-mediated tumor growth and progression.

Antagonists of IAP proteins as cancer therapeutics - Corrected Proof

Jasmin N. Dynek, Domagoj Vucic — 2010-08-04

Abstract: Inhibitor of apoptosis (IAP) proteins play pivotal roles in cellular survival by blocking apoptosis, modulating signal transduction, and affecting cellular proliferation. Through their interactions with inducers and effectors of apoptosis IAP proteins can effectively suppress apoptosis triggered by diverse stimuli including death receptor signaling, irradiation, chemotherapeutic agents, or growth factor withdrawal. Evasion of apoptosis, in part due to the action of IAP proteins, enhances resistance of cancer cells to treatment with chemotherapeutic agents and contributes to tumor progression. Additionally, IAP genes are known to be subject to amplification, mutation, and chromosomal translocation in human malignancies and autoimmune diseases. In this review we will discuss the role of IAP proteins in cancer and the development of antagonists targeting IAP proteins for cancer treatment.

Targeting apoptosis pathways in cancer by Chinese medicine - Corrected Proof

Min Li-Weber — 2010-08-04

Abstract: The traditional Chinese medicine (TCM) uses a combination of different natural products based on practical experiences. To better understand the therapeutic functions of TCM, large efforts have been made to identify the principle constituents of TCM and to unravel the molecular mechanisms behind the efficacy observed. This review aims to summarize research results obtained from the most intensively studied TCM phytochemical compounds namely the alkaloids Berberine, Evodiamine; anthraquinones Emodin, Aloe-emodin, Rhein; the terpenoids Artemisinin, Celastrol, Triptolide; the flavones Apigenin, Chrysin, Wogonin, Baicalein; and the cyclopenta[b]benzofuran derivatives Rocaglamide. Most of them have been originally identified as anti-inflammatory and anti-viral reagents and are now known to also possess anti-tumor activities by targeting the apoptosis pathways in cancer. This review also intends to give an overview of the mechanisms of action identified so far. These breakthrough findings may have important implications for targeted-cancer therapy and for modernization of TCM.

Small compound inhibitors of basal glucose transport inhibit cell proliferation and induce apoptosis in cancer cells via glucose-deprivation-like mechanisms - Corrected Proof

Yi Liu, Weihe Zhang, Yanyan Cao, Yan Liu, Stephen Bergmeier, Xiaozhuo Chen — 2010-08-02

Abstract: Cancer cells depend heavily on glucose as both energy and biosynthesis sources and are found to upregulate glucose transport and switch their main energy supply pathway from oxidative phosphorylation to glycolysis. These molecular and metabolic changes also provide targets for cancer treatment. Here we report that novel small molecules inhibited basal glucose transport and cell proliferation, and induced apoptosis in lung and breast cancer cells without affecting much their normal cell counterparts. Cancer cells survived the compound treatment lost their capability to proliferate. Mechanistic study indicates that the cancer cell inhibition by the test compounds has a component of apoptosis and the induced apoptosis was p53-independent and caspase 3-dependent, similar to those resulted from glucose deprivation. Compound treatment also led to cell cycle arrest in G1/S phase. The inhibition of cancer cell growth was partially relieved when additional glucose was supplied to cells, suggesting that the inhibition was due to, at least in part, the inhibition of basal glucose transport. When used in combination, the test compounds demonstrated synergistic effects with anticancer drugs cisplatin or paclitaxel in inhibition of cancer cell growth. All these results suggest that these glucose transport inhibitors mimic glucose deprivation and work through inhibiting basal glucose transport. These inhibitors have the potential to complement and replace traditional glucose deprivation, which cannot be used in animals, as new tools to study the effects of glucose transport and metabolism on cancer and normal cells.

Targeting apoptosis pathways by natural compounds in cancer: Marine compounds as lead structures and chemical tools for cancer therapy - Corrected Proof

Karin von Schwarzenberg, Angelika M. Vollmar — 2010-08-02

Abstract: Natural compounds derived from marine organisms have shown a wide variety of anti-tumor effects and a lot of attention has been drawn to further development of the isolated compounds. A vast quantity of individual chemical structures from different organisms has shown a variety of apoptosis inducing mechanisms in a variety of tumor cells. The bis-steroidal cephalostatin 1 for example, induces apoptosis via activation of caspases whereas the polyketide discodermolide inhibits cell growth by binding to and stabilizing microtubule and salisporamide A, the product of an actinobacterial strain, is an inhibitor of the proteasome. This great variety of mechanisms of action can help to overcome the multitude of resistances exhibited by different tumor specimens. Products from marine organisms and their synthetic derivates are therefore an important source for new therapeutics for single agent or combined therapy with other chemotherapeutics to support the struggle against cancer.

Combinations of mTORC1 inhibitor RAD001 with gemcitabine and paclitaxel for treating non-Hodgkin lymphoma - Corrected Proof

2010-08-02

Abstract: Single-agent mammalian target of rapamycin complex 1 (mTORC1) inhibitors have recently been reported as effective salvage treatment in non-Hodgkin lymphoma (NHL). The combined effect of mTORC1 inhibitor, RAD001, with chemotherapeutic agents used for relapsed or refractory NHL was examined. Synergistic interactions were observed for RAD001 plus gemcitabine or paclitaxel in six NHL cell lines; enhanced gemcitabine- and paclitaxel-induced caspase-dependent apoptosis associated with down-regulation of mTOR signaling was detected. Synergistic interactions were also observed with RAD001 plus gemcitabine and paclitaxel. In conclusion, synergistic cytotoxicity was observed with RAD001 plus gemcitabine and paclitaxel in NHL cells. Combination therapy with these three drugs should be examined in patients with refractory or relapsed NHL.

NO-releasing NSAIDs suppress NF-κB signaling in vitro and in vivo through S-nitrosylation - Corrected Proof

2010-08-02

Abstract: NO-NSAIDs are promising anticancer drugs, comprising an NSAID, an NO-releasing moiety, and a spacer linking them. Although the effect of NO-NSAIDs on a wide variety of signaling and other cellular mechanisms has been deciphered, a key question remains unanswered, that being the role of NO to the overall biological effect of these agents. It has been shown that NO can directly modify sulfhydryl residues of proteins through S-nitrosylation and induce apoptosis. We studied 3 NO-NSAIDs having a different NSAID, spacer, and NO-releasing moiety. In vitro: aspirin, NO-ASA, naproxen, and NO-naproxen inhibited HT-29 human colon cancer cell growth, the IC50s being >5000, 192±6, 2800±210 and 95±5μM at 24h, respectively. NO-Aspirin and NO-naproxen reduced NF-κB protein levels, and activated caspase-3 enzyme in a dose- and time-dependent manner. Based on the biotin switch assay, NO-ASA and NO-naproxen S-nitrosylated NF-κB p65 in a time-dependent manner. Pretreatment of the cells with carboxy-PTIO, abrogated the S-nitrosylation of NF-κB p65. In vivo: rats treated with NO-ASA, NONO-ASA, and NO-naproxen showed S-nitrosylation of NF-κB p65 in the stomach tissue, increases in plasma TNF-α, and reductions in mucosal PGE2 levels. These data provide a mechanistic role for NO and a rational for the chemopreventive effects of NO-NSAIDs.

Inhibition of cyclooxygenase-2-dependent survivin mediates decursin-induced apoptosis in human KBM-5 myeloid leukemia cells - Corrected Proof

2010-08-02

Abstract: We demonstrate that decursin induces apoptosis via regulation of cyclooxygenase-2 (COX-2) and survivin in leukemic KBM-5 cells. By activating an apoptotic machinery, decursin is cytotoxic to KBM-5 cells. In this apoptotic process, decursin can activate caspase family members and triggers PARP cleavage. At the same time, the expression of COX-2 and survivin in the cells is downregulated. Furthermore, decursin is in synergy with COX-2 inhibitor, celecoxib or NS398 for the induction of apoptosis. Overall, these results suggest that decursin, via inhibiting COX-2 and survivin, sensitizes human leukemia cells to apoptosis and is a potential chemotherapeutic agent to treat this disease.

Icariin, a natural flavonol glycoside, induces apoptosis in human hepatoma SMMC-7721 cells via a ROS/JNK-dependent mitochondrial pathway - Corrected Proof

2010-08-02

Abstract: In this study, the anticancer effect of icariin, a natural flavonol glycoside, against human hepatoma SMMC-7721 cells and the underlying mechanisms were investigated. Icariin triggered the mitochondrial/caspase apoptotic pathway indicated by enhanced Bax-to-Bcl-2 ratio, loss of mitochondrial membrane potential, cytochrome c release, and caspase cascade. Moreover, icariin induced a sustained activation of the phosphorylation of c-Jun N-terminal kinase (JNK) but not p38 and ERK1/2, and SP600125 (an inhibitor of JNK) almost reversed icariin-induced apoptosis in SMMC-7721 cells. In addition, icariin provoked the generation of reactive oxygen species (ROS) in SMMC-7721 cells, while the antioxidant N-acetyl cysteine almost completely blocked icariin-induced JNK activation and apoptosis. Taken together, these findings suggest that icariin induces apoptosis through a ROS/JNK-dependent mitochondrial pathway.

Anti-tumor and radiosensitization activities of the iron chelator HDp44mT are mediated by effects on intracellular redox status - Corrected Proof

Junqiang Tian, Donna M. Peehl, Wengwei Zheng, Susan J. Knox — 2010-08-02

Abstract: A novel iron chelator, HDp44mT, has been reported to have potent anti-proliferative effects on cancer cells; however, the underlying mechanism of action is not well understood. In this study, we characterized the cytotoxic effect of HDp44mT in a chemo- and radio-resistant cell line (PC-3) of prostatic cancer origin. The activity of HDp44mT at nM concentrations was dependent on the intracellular GSH and atmospheric O2 concentration, rather than iron deprivation. HDp44mT also radiosensitized PC-3 cells in a GSH-dependent manner. Interestingly, this radiosensitizing effect was observed under aerobic and, to a larger extent, hypoxic conditions, suggesting its potential utility as a radiosensitizer for some radioresistant tumors.

Preferential induction of G1 arrest in androgen-responsive human prostate cancer cells by androgen receptor signaling antagonists DL3 and antiandrogen bicalutamide - Corrected Proof

Shan Lu, Zongqin Tan, Matthew Wortman, Shan Lu, Zhongyun Dong — 2010-08-02

Abstract: The purpose of this study was to further characterize cell growth-inhibitory effects of a recently identified androgen receptor (AR) signaling inhibitor 6-amino-2-[2-(4-tert-butyl-pnenoxy)-ethylsulfanyl]-1H-pyrimidin-4-one (DL3)5 and antiandrogen bicalutamide (Bic). DL3 was more potent than Bic in induction of G1 arrest and reduction of G1-related cell cycle protein expression in AR-positive LNCaP cells. DL3, but not Bic, moderately inhibited growth of AR-negative PC-3 cells independent of G1 arrest. The data indicated that DL3 inhibit cell growth in both AR-dependent and -independent manners and is potentially a potent therapeutic agent for the management of advanced human prostate cancer.

N-Acetylcysteine interacts with copper to generate hydrogen peroxide and selectively induce cancer cell death - Corrected Proof

2010-07-28

Abstract: A variety of metal-binding compounds have been found to exert anti-cancer activity. We postulated that N-acetylcysteine (NAC), which is a membrane-permeable metal-binding compound, might have anti-cancer activity in the presence of metals. We found that NAC/Cu(II) significantly alters growth and induces apoptosis in human cancer lines, yet NAC/Zn(II) and NAC/Fe(III) do not. We further confirmed that this cytotoxicity of NAC/Cu(II) is attributed to reactive oxygen species (ROS). These findings indicate that the combination of Cu(II) and thiols generates cytotoxic ROS that induce apoptosis in cancer cells. They also indicate a fourth class of anti-neoplastic metal-binding compounds, the “ROS generators”.

Helminths in human carcinogenesis - Corrected Proof

Bernard Fried, Aditya Reddy, David Mayer — 2010-07-28

Abstract: This review examines the salient literature on selected helminths involved in carcinogenicity in humans and updates information in an earlier review on cancer and helminths by Mayer and Fried (2007, Advances in Parasitology 65, 239–296). The earlier review was concerned with various helminths, i.e., trematodes, cestodes, and nematodes, that are definitely implicated as being carcinogenic. This review examines only those helminths, all of which turn out to be trematodes, that are definitely implicated as being carcinogenic. These trematodes are the blood flukes Schistosoma haematobium, associated with inducing human carcinoma of the urinary bladder and the liver flukes Opisthorchis viverrini and Clonorchis sinensis, associated with inducing cancer of the bile duct (cholangiocarcinoma) and cancer of the liver (hepatocarcinoma) in humans. The review examines mainly the epidemiology and pathology of these helminthic infections in humans and considers what we know about the mechanisms associated with the carcinogenicity of these three trematodes in humans.

1α, 25-Dihydroxyvitamin D regulates hypoxia-inducible factor-1α in untransformed and Harvey-ras transfected breast epithelial cells - Corrected Proof

Yan Jiang, Wei Zheng, Dorothy Teegarden — 2010-07-26

Abstract: The purpose of this study was to determine the mechanism by which 1α, 25-dihydroxyvitamin D (1,25(OH)2D) alters hypoxia-inducible factor-1α (HIF-1α) protein in untransformed and Harvey-ras (H-ras) oncogene transfected MCF10A breast epithelial cells. Treatment with 1,25(OH)2D (10nM) increased both mRNA (2.55±0.6-fold vs. vehicle, p=0.03) and protein levels (2.37±0.3-fold vs. vehicle, p<0.0001) of HIF-1α in MCF10A cells in 12h, which remained elevated at 24h. However, in H-ras transfected MCF10A cells, 1,25(OH)2D treatment increased HIF-1α protein level (2.08±0.38-fold vs. vehicle, p=0.05) at 12h, with no change in mRNA level and HIF-1α protein level returned to baseline after 24h. A transcription inhibitor prevented the 1,25(OH)2D induction of HIF-1α protein and mRNA levels in MCF10A cells, but failed to alter the induction of HIF-1α protein level in H-ras transfected MCF10A cells. On the other hand, inhibition of proteasomal degradation prevented the 1,25(OH)2D-induced HIF-1α protein level in H-ras transfected MCF10A but not in MCF10A cells. These results support that 1,25(OH)2D regulates HIF-1α protein level via transcriptional regulation in MCF10A cells in contrast to through proteosomal degradation with the presence of H-ras oncogene in MCF10A cells.

Luteolin induces G1 arrest in human nasopharyngeal carcinoma cells via the Akt–GSK-3β–Cyclin D1 pathway - Corrected Proof

Chye-Sun Ong, Jing Zhou, Choon-Nam Ong, Han-Ming Shen — 2010-07-26

Abstract: Luteolin, a plant flavonoid is known to possess multiple biological activities such as anti-inflammation, anti-allergy, anti-oxidant as well as anti-cancer. At present, the anti-proliferative potential of luteolin has not been fully understood. In this study, we focused on the effect of luteolin on cell cycle regulation in human nasopharyngeal carcinoma (NPC) cells. First, we found that luteolin inhibited cell cycle progression at G1 phase and prevented entry into S phase in a dose- and time-dependent manner. Next, it was found that luteolin treatment led to down-regulation of cyclin D1 via enhanced protein phosphorylation and proteasomal degradation, leading to reduced CDK4/6 activity and suppression of retinoblastoma protein (Rb) phosphorylation, and subsequently inhibition of the transcription factor E2F-1. In search of the molecular mechanisms underlying luteolin-mediated cyclin D1 down-regulation, it was found that luteolin was capable of suppressing Akt phosphorylation and activation, resulting in de-phosphorylation and activation of glycogen synthase kinase-3β (GSK-3β). Activated GSK-3β then targeted cyclin D1, causing phosphorylation of cyclin D1 at Thr286 and subsequent proteasomal degradation. The above findings were reinforced by the fact that luteolin was able to abrogate the effect of insulin on the Akt/GSK-3β/Cyclin D1 pathway, resulting in suppression of insulin-induced cell proliferation. Since Akt is often over-activated in many human cancers including NPC, it is thus believed that data from this study support the potential application of luteolin as a chemotherapeutic or chemopreventive agent in human cancer.

TGF-β inhibits metastasis in late stage human squamous cell carcinoma of the skin by a mechanism that does not involve Id1 - Corrected Proof

2010-07-22

Abstract: It is now generally accepted that TGF-β acts as a pro-metastatic factor in advanced human breast cancer. However, it is well documented, that TGF-β is context dependent, and whether the TGF-β pathway switches to promote metastasis during the progression of squamous cell carcinoma (SCC) is unknown. This study examined the role of TGF-β signalling in SCC using a series of genetically related keratinocyte cell lines representing later stages of the disease, stably transduced with a dominant negative TβRII cDNA (dnTβRII). We demonstrated that clones expressing dnTβRII lost their growth inhibitory response to TGF-β in vitro, while ligand expression remained unchanged. Following transplantation of transduced cells to athymic mice in vivo, we showed that attenuation of the TGF-β signal resulted in a loss of differentiation and increased metastasis. In human tissue samples loss of TGF-β signal transduction as measured by pSmad2 activity also correlated with a loss of differentiation. Id1, previously shown to be down regulated by TGF-β, an inhibitor of differentiation and associated with metastasis, was weakly expressed in focal areas of a small number of human tumours but expression did not correlate with low levels of pSmad2. Our data demonstrate that TGF-β does not switch to promote metastasis in late stage human SCC of the skin and that inhibition of TGF-β signalling results in a loss of differentiation and increased metastasis in the later stages of this disease.

Activated Notch signaling is required for hepatitis B virus X protein to promote proliferation and survival of human hepatic cells - Corrected Proof

Fan Wang, Haiyan Zhou, Xiumei Xia, Qian Sun, Ying Wang, Bin Cheng — 2010-07-20

Abstract: Hepatitis B virus X protein (HBx) is a multifunctional oncoprotein which plays a crucial role in the pathogenesis of hepatocellular carcinoma (HCC). However, the exact mechanisms remain controversial. Here we show that HBx strongly stimulated cell growth, promoted cell cycle progression and inhibited apoptosis of human non-tumor hepatic cell line L02 cells. It also accelerated tumor formation of L02 cells in BALB/c nude mice. Furthermore, Notch signaling components were upregulated in HBx-expressing L02 cells compared to normal L02 cells. However, blocking Notch signaling with a γ-secretase inhibitor N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester (DAPT) attenuated cell growth, shortened the S phase of cell cycle and promoted apoptosis of HBx-expressing L02 cell in a dose- and time-dependent manner, but normal L02 cells were not significantly affected by Notch signaling blocking. Therefore, our findings demonstrate that HBx could promote the growth of human non-tumor hepatic cell line L02 cells both in vitro and in vivo, which may require the activation of Notch signaling pathway.

Cryptotanshinone sensitizes DU145 prostate cancer cells to Fas(APO1/CD95)-mediated apoptosis through Bcl-2 and MAPK regulation - Corrected Proof

2010-07-20

Abstract: Fas/APO-1/CD95, a member of the tumor necrosis factor (TNF) receptor superfamily, is a potential anti-cancer factor as it can induce apoptosis in tumor cells. However, despite the fact that many cancer cells express Fas on the membrane, some tumors such as prostate cancer display resistance to Fas-induced apoptosis. In these cases, combination therapy using chemotherapeutic agents and Fas may be more suitable than therapy using Fas alone. In the present study, we demonstrate that the apoptosis inhibitory protein, Bcl-2, was highly expressed in response to Fas in DU145 prostate cancer cells, thereby conferring resistance to apoptosis. We have screened a number of naturally occurring products that may overcome this resistance. Here we report that cryptotanshinone, the major tanshinone isolated from Salvia miltiorrhiza Bunge, can suppress Bcl-2 expression and augment Fas sensitivity in DU145 cells. We further show that JNK and p38 MAPK act upstream of Bcl-2 expression in Fas-treated DU145 cells, and that cryptotanshinone significantly blocked activation of these kinases. Moreover, cryptotanshinone sensitized several tumor cells to a broad range of anti-cancer agents. Collectively, our data suggest that cryptotanshinone has therapeutic potential in the treatment of human prostate cancer.

miR-27a regulates the growth, colony formation and migration of pancreatic cancer cells by targeting Sprouty2 - Corrected Proof

Yihui Ma, Shuangni Yu, Wugan Zhao, Zhaohui Lu, Jie Chen — 2010-07-20

Abstract: MicroRNAs are short regulatory RNAs. A growing body of data implicates altered miRNA participate in the development of cancers and miR-27a is abnormally upregulated in several types of cancers identified as an oncogene. Although overexpressed in pancreatic adenocarcinoma, the oncogenic role of miR-27a has not yet been reported. In this study, we showed that inhibition of miR-27a suppressed the growth, colony formation and migration of pancreatic cancer cells. By using a reporter-screening assay, we discovered that the 3′UTR of Sprouty2 (Spry2) carried a putative miR-27a binding site. Furthermore, the Spry2 protein, which has a low expression level in pancreatic adenocarcinoma, was upregulated by transfection with a miR-27a inhibitor. The data reported here are the first to indicate that miR-27a plays an oncogenic role by targeting Spry2 and modulating the malignant, biological behavior of pancreatic cancer cells. This suggests the potential for miR-27a to be used as a target in the diagnosis and treatment of pancreatic adenocarcinoma.

PTHrP promotes colon cancer cell migration and invasion in an integrin α6β4-dependent manner through activation of Rac1 - Corrected Proof

Ramanjaneya V. Mula, Vandanajay Bhatia, Miriam Falzon — 2010-07-16

Abstract: Parathyroid hormone-related protein (PTHrP) is expressed by human colon cancer tissue and cell lines. Rac1 GTPase enhances colon cancer cell migration and invasion. Here we report a positive correlation between PTHrP expression and Rac1 activity in LoVo (human colon cancer) cells. The positive effects of PTHrP on Rac1 activity and on cell migration and invasion are mediated via the guanine nucleotide exchange factor Tiam1. Knockdown of integrin α6β4, which is upregulated by PTHrP, negates the PTHrP-mediated increase in Rac1 activation. Integrin α6β4 signals synergistically with growth factor receptors to activate the phosphatidylinositol 3-kinase (PI3-K) pathway. Chemical inhibition of PI3-K negates the PTHrP-mediated effects on Tiam1 and Rac1 activity. Tumors from PTHrP-overexpressing LoVo cells also show increased expression of Tiam1. Taken together, these observations provide evidence of a link between PTHrP and Rac1 activity through integrin α6β4, resulting in enhanced cell migration and invasion. Targeting PTHrP production in colon cancer may thus prove therapeutically beneficial.

Growth hormone-releasing hormone antagonist induces apoptosis of human endometrial cancer cells through PKCδ-mediated activation of p53/p21 - Corrected Proof

2010-07-14

Abstract: The growth hormone-releasing hormone (GHRH) antagonists have been shown to inhibit growth of human cancer cells, but the underlying molecular mechanisms and their actions have not been fully investigated. In this study, we first showed that GHRH-R splice variant 1 (SV1) was expressed in two human endometrial cancer cell lines, Ishikawa and ECC-1. By using MTT assay, immunoblotting for cleaved caspase-3 and TUNEL assays, we found that cell growth inhibition and apoptosis were induced in GHRH antagonist, JMR-132-treated cells by activating PKCδ and could be inhibited by treatment with PKC inhibitor, GF109203X. In addition, activation and protein expression of p53 as well as the expression of its downstream effector, p21, were increased by JMR-132 treatment. Moreover, JMR-132-induced p53 and p21 expression were diminished by treatment with PKC inhibitor. Knockdown of endogenous p53 and p21 by siRNAs abolished the JMR-132-induced cell growth inhibition and apoptosis. This study demonstrates a novel mechanism in which GHRH antagonist-induced cell growth inhibition and apoptosis through PKCδ-mediated activation of p53/p21 in human endometrial cancer cells. These findings may suggest the feasibility of GHRH antagonists as a therapeutic approach for human cancer.

Ursolic acid induces doxorubicin-resistant HepG2 cell death via the release of apoptosis-inducing factor - Corrected Proof

2010-07-14

Abstract: Ursolic acid (UA), a triterpenoid compound isolated previously from Oldenlandia diffusa, which is a Traditional Chinese Medicine used to treat cancer, was found to inhibit the proliferation of doxorubicin-resistant human hepatoma cell line (R-HepG2) through apoptosis as shown by externalization of phosphatidyl serine, morphological changes and loss of mitochondrial membrane potential. UA could activate Bak but not Bax, which implied that Bak may play an important role in UA-induced apoptosis. Furthermore, the death of R-HepG2 cells induced by UA was found to be mainly through the caspase-independent apoptosis-inducing factor (AIF) signaling pathway which was evidenced by: (a) the pan-caspase inhibitor and the specific caspase inhibitor had only modest protective effect against UA; (b) UA treatment caused the nuclear translocation of AIF, which is retained in the mitochondria in untreated R-HepG2 cells; (c) cells that had been treated with human AIF-specific siRNA could resist cell death induced by UA. In addition, a further animal study showed that UA was effective against R-HepG2 cells in vivo with negligible body weight loss and damage towards the liver, heart and spleen. Most importantly, immunohistochemical staining in animal tissues also suggested that UA also significantly inhibited the growth of R-HepG2 cells in nude mice through the AIF signaling pathway.

S-trityl-L-cysteine derivative induces caspase-independent cell death in K562 human chronic myeloid leukemia cell line - Corrected Proof

2010-07-12

Abstract: Effect of CF3-STLC, a potent kinesin spindle protein (KSP) inhibitor, on K562 human CML cell line was investigated. Treatment with CF3-STLC induced mitotic arrest of the cell cycle with the appearance of characteristic monoastral spindles, subsequent apoptotic cell death and cleavage of PARP-1, caspase-3, and 4E-BP1. The wide ranging caspase inhibitor z-VAD fmk prevented the cleavage of caspase-3 and 4E-BP1, but failed to attenuate PARP-1 cleavage or cell death triggered by CF3-STLC. These results suggest that CF3-STLC can induce apoptotic cell death in a caspase-independent manner, and may work effectively as an anti-cancer agent for hematological malignancies.

Chk1 inhibitor Gö6976 enhances the sensitivity of nasopharyngeal carcinoma cells to radiotherapy and chemotherapy in vitro and in vivo - Corrected Proof

Zizhen Feng, Shuangbing Xu, Mengzhong Liu, Yi-Xin Zeng, Tiebang Kang — 2010-07-09

Abstract: Nasopharyngeal carcinoma (NPC) is a malignant tumor. This type of carcinoma has a low 5-year patient survival rate. Thus, there is a need for improved therapeutics. We determined that the Chk1 inhibitor Gö6976 enhanced the sensitivity of CNE1 and CNE2 cells to ionizing radiation (IR) or cisplatin by abrogating S and G2/M arrest and subsequently promoting apoptosis. Furthermore, Gö6976 appeared to sensitize NPC xenografts in nude mice to IR or cisplatin treatment. This is the first report to show that the Chk1 inhibitor Gö6976 sensitizes NPC cells to treatment using in vitro and in vivo models.

miR-126 functions as a tumour suppressor in human gastric cancer - Corrected Proof

2010-07-09

Abstract: MicroRNAs have emerged as important gene regulators and are recognised as key players in carcinogenesis. In the present study, we show that miR-126 was significantly down-regulated in gastric cancer tissues compared with matched normal tissues and was associated with clinicopathological features, including tumour size, lymph node metastasis, local invasion and tumour-node-metastasis (TNM) stage. Ectopic expression of miR-126 in SGC-7901 gastric cancer cells potently inhibited cell growth by inducing cell cycle arrest in G0/G1 phase, migration and invasion in vitro as well as tumorigenicity and metastasis in vivo. Mechanistically, we identified the adaptor protein Crk as a target of miR-126. Taken together, our results suggest that miR-126 may function as a tumour suppressor in gastric cancer, with Crk as a direct target.

Inhibition of androgen receptor and Cdc25A phosphatase as a combination targeted therapy in molecular apocrine breast cancer - Corrected Proof

Ali Naderi, Ji Liu — 2010-07-07

Abstract: Molecular apocrine breast cancer is an estrogen receptor negative subtype characterized by the over-expression of steroid response genes. In this study we investigate the therapeutic effects of persistent ERK phosphorylation using a Cdc25A phosphatase inhibitor, PM-20 in combination with AR inhibition using flutamide in this subtype. Our findings demonstrate a significant synergy with this combination in reducing cell viability and growth. Furthermore, we show that the mechanism of this effect involves a cross-talk between the AR and ERK signalling pathways. Moreover, using a xenograft molecular apocrine model we demonstrate that the combination therapy results in a significantly better therapeutic response compared to monotherapy and control groups manifesting as reductions in tumor growth, proliferation index, and cellularity. This study demonstrates that the combined application of AR and Cdc25A inhibitors is a promising therapeutic strategy in molecular apocrine breast cancer.

Transcriptional down-regulation of IGFBP-3 in human hepatocellular carcinoma cells is mediated by the binding of TIA-1 to its AT-rich element in the 3′-untranslated region - Corrected Proof

Kothandharaman Subramaniam, London Lucien P.J. Ooi, Kam M. Hui — 2010-07-05

Abstract: Insulin-like growth factor binding protein-3 (IGFBP-3) plays key roles in regulating cell growth, differentiation, and apoptosis in a variety of cellular systems. We have observed significant down-regulation of IGFBP-3 expression in primary human hepatocellular carcinoma (HCC) tissues when compared to adjacent histologically normal tissues. In this study, we functionally mapped the entire 3′-UTR of the IGFBP-3 mRNA, spanning 1471nt and identified a 210bp fragment consisting of AT-rich elements at the distal downstream region preceding the consensus pre-mRNA polyadenylation signal that provide high affinity binding for TIA-1 to mediate the specific suppression of IGFBP-3 expression in human HCC cells.

Combating apoptosis and multidrug resistant cancers by targeting lysosomes - Corrected Proof

Line Groth-Pedersen, Marja Jäättelä — 2010-07-02

Abstract: Acquired therapy resistance is one of the prime obstacles for successful cancer treatment. Partial resistance is often acquired already during an early face of tumor development when genetic changes causing defects in classical caspase-dependent apoptosis pathway provide transformed cells with a growth advantage by protecting them against various apoptosis inducing stimuli including transforming oncogenes themselves and host immune system. Apoptosis defective cells are further selected during tumor progression and finally by apoptosis inducing treatments. Another form of resistance, multidrug resistance, arises during cancer treatment when cancer cells with effective efflux of cytotoxic agents escape the therapy. Remarkably, induction of lysosomal membrane permeabilization has recently emerged as an effective way to kill apoptosis resistant cancer cells and some lysosome targeting drugs can also re-sensitize multidrug resistant cells to classical chemotherapy. In this review, we highlight recent data on lysosomal cell death pathways and their implications for the future treatment of apoptosis defective and multidrug resistant aggressive tumors.

Generation 4 polyamidoamine dendrimers is a novel candidate of nano-carrier for gene delivery agents in breast cancer treatment - Corrected Proof

Pei Wang, Xin-Han Zhao, Zhi-Yu Wang, Min Meng, Xu Li, Qian Ning — 2010-07-01

Abstract: Polyamidoamine dendrimer (PAMAM-D) is a new gene vector developed in recent years. In this study, we successfully prepared G4PAMAM and detected its unique structure by NMR, FITR and TEM. We revealed that G4PAMAM could bind to human erythrocytes and BSA through electrostatic interaction respectively, and caused haemolysis and reduced bioavailability. However, G4PAMAM-VEGF-ASODN (antisense oligodeoxynucleotides) complex could prevent G4PAMAM from binding to the erythrocytes and BSA and remained stable as a conjugate, therefore the toxicity of the complex was reduced. Meanwhile, we showed that G4PAMAM could be used as a gene vector to deliver AODNs into breast cancer MDA-MB-231 cells without significant cell toxicity, and it enhanced cellular uptake of ODNs. In vivo experiment of human breast tumor xenograft mice model, G4PAMAM also showed more efficiency of accumulating VEGF-ASODN to inhibit the tumor vascularization of breast tumor tissue than naked AODN. Furthermore, G4PAMAM could protect DNA in cytoplasm from digestion of restriction enzymes, which was important to become an effective tool in gene research and therapy.

The anti-tumor agent, p-DDAP potently suppresses proliferation through apoptosis in human neuroblastoma NB-39-nu cells - Corrected Proof

2010-06-28

Abstract: Retinoic acid (RA) is a chemotherapeutic agent used to induce neuronal cellular differentiation of neuroblastoma. However, because treatment with RA is associated with the side-effect of nyctalopia, efforts have been underway to identify new compounds that could potentially overcome these drawbacks. As part of these studies we have examined anti-cancer effects on the neuroblastoma NB-39-nu cells of p-dodecylaminophenol (p-DDAP), a novel derivative of N-(4-hydroxyphenyl) retinamide (4-HPR). p-DDAP suppresses proliferation, and induces G0/G1 arrest and apoptosis to a greater extent than RA and 4-HPR. Neuronal differentiation was not detected in p-DDAP-treated cells. Since p-DDAP is not toxic and does not reduce blood retinol levels, p-DDAP might be a useful anti-neuroblastoma drug having reduced side-effects.

Survivin mediates self-protection through ROS/cdc25c/CDK1 signaling pathway during tumor cell apoptosis induced by high fluence low-power laser irradiation - Corrected Proof

Jiru Chu, Shengnan Wu, Da Xing — 2010-06-25

Abstract: Survivin, an important member of inhibitor-of-apoptosis (IAP) family, can be up-regulated by various pro-apoptotic stimuli, such as UV, photodynamic therapy (PDT) and cisplatin. High fluence low-power laser irradiation (HF-LPLI) is a newly discovered pro-apoptotic stimulator. The anti-apoptotic mechanism of survivin during HF-LPLI-induced apoptosis is still not investigated. Here, we report that HF-LPLI up-regulates survivin activity through reactive oxygen species (ROS)/cdc25c protein phosphatase (cdc25c)/cyclin-dependent kinase (CDK1) signaling pathway in human lung adenocarcinoma cells (ASTC-a-1). The up-regulation of survivin activity can reduce HF-LPLI-induced apoptosis, while down-regulation of the activity can promote the apoptosis. In addition, activated survivin delays mitochondrial depolarization, cytochrome c release, caspase-9 and Bax activation, all of which are typical pro-apoptotic events of cell apoptosis induced by HF-LPLI. On the basis of the present studies, we conclude that survivin can mediate self-protection during tumor cell apoptosis caused by HF-LPLI.

Recombinant high density lipoprotein reconstituted with apolipoprotein AI cysteine mutants as delivery vehicles for 10-hydroxycamptothecin - Corrected Proof

Xinbo Zhang, Baosheng Chen — 2010-06-25

Abstract: 10-Hydroxycamptothecin (HCPT) is an effective anticancer agent whose therapeutic potential is limited by poor water-solubility and selectivity, short half-life and side effects. It has been shown that high density lipoprotein (HDL) or recombinant HDL (rHDL) reconstituted with wide-type apolipoprotein AI (apoAIwt) is an effective drug delivery model because of its specific structural characteristics and the targeted receptor-mediated uptake mechanism. In this study, the apoAIMilano (apoAIM) mutant with higher receptor affinity was chosen as a potential delivery vehicle from seven cysteine mutants of apoAI constructed by our laboratory. rHDL–HCPT nanoparticles reconstituted with apoAIM, named as rHDLM–HCPT, seemed to be primarily spherical model with mean diameter were 22.39±10.25nm, which is similar with the diameter of natural HDL. rHDLM–HCPT showed a very steady sustained release pattern in vitro and increased the drug concentration in major organs, relative to free HCPT. Furthermore, in comparison with free HCPT, rHDLM–HCPT nanoparticles increased the cytotoxicity of HCPT by 70 and 50 times in SKOV-3 and HCT-116 cells. The data presented in this study indicate that rHDLM reconstituted with apoAIM could be exploited as a potential delivery vehicle of HCPT with controlled release, enhanced tissue distribution and higher cytotoxicity.

All-trans retinoic acid downregulates ALK in neuroblastoma cell lines and induces apoptosis in neuroblastoma cell lines with activated ALK - Corrected Proof

Hitoyasu Futami, Ryuichi Sakai — 2010-06-24

Abstract: Recently, gene amplification and gain-of-function mutations of ALK have been found in some neuroblastoma cell lines and clinical tumor samples. We have previously reported that knockdown of ALK by RNAi induced apoptosis in neuroblastoma cells with gene amplification of ALK. We report that all-trans retinoic acid (ATRA) downregulates ALK in neuroblastoma cell lines. Downregulation of ALK protein by ATRA was accompanied by apoptosis in neuroblastoma cells with gene amplification or gain-of-function mutation of ALK but not in neuroblastoma cells without these genetic alterations. These results suggest that ALK downregulation by ATRA might lead to apoptosis in neuroblastoma cells with activated ALK.

Hypoxia and retinoic acid-inducible NDRG1 expression is responsible for doxorubicin and retinoic acid resistance in hepatocellular carcinoma cells - Corrected Proof

2010-06-23

Abstract: Hypoxia may activate survival signals in cancer cells. Moreover, hypoxic cells are less sensitive than normoxic cells to doxorubicin cytotoxicity, a potent activator of the p53 tumor suppressor gene. N-myc downstream-regulated gene-1 (NDRG1) is a hypoxia- and retinoic acid-inducible protein, and has been previously implicated in carcinogenesis. As this protein is also a downstream target of p53 and hepatocellular carcinoma (HCC) cells frequently evidence resistance to retinoic acid (RA) cytotoxicity, we attempted to determine whether the suppression of NDRG1 expression may sensitize HCC cells to doxorubicin and/or RA cytotoxicity. HCC cells expressed NDRG1 protein, and the expression of this protein was hypoxia- and RA-inducible. Doxorubicin treatment induced HCC cell cytotoxicity via the activation of mitochondrial apoptotic signals, including caspase-9 activation. Hypoxic HCC cells are less sensitive to doxorubicin-induced apoptosis. The suppression of NDRG1 expression either by siRNA or flavopiridol sensitized hypoxic HCC cells to doxorubicin cytotoxicity, and this was attributed to more profound augmentation of JNK and caspase-9 activation. The suppression of NDRG1 expression also sensitized RA-resistant HCC cells to RA-induced apoptosis, and this sensitization was more apparent in hypoxic HCC cells than in normoxic cells. Glutaredoxin2 expression was down-regulated in NDRG1-suppressed HCC cells. These results show that hypoxia- and RA-inducible NDRG1 expression is responsible for doxorubicin and RA resistance in HCC cells. Thus, the selective interruption of NDRG1 signaling may prove to be therapeutically useful in HCCs, particularly in the advanced infiltrative type of tumors exposed to hypoxic environments.

Tumor specific low pH environments enhance the cytotoxicity of lovastatin and cantharidin - Corrected Proof

2010-06-18

Abstract: In tumor cell masses, the extracellular pH decreases below 6.5. The effect of external acidic pH on the efficacy of 24 chemical compounds including molecular-targeted inhibitors and anti-tumor reagents was investigated in human cancer cells. Lovastatin showed no cytotoxicity in mesothelioma or pancreatic carcinoma cells at concentrations up to 10μM and pH around 7.4, but 10μM lovastatin decreased the survival of these cells below 40% at acidic pH. Lovastatin inhibits HMG-CoA reductase, resulting in a decrease in the levels of cholesterol and prenylated proteins. An inhibitor of the former pathway showed pH-independent cytotoxic activity, whereas an inhibitor of the latter pathway had stronger activity at acidic pH. The inhibitory efficacy of cantharidin also increased at acidic pH. On the other hands, no pH dependency or slightly impaired efficacy at low pH conditions was observed in other 20 reagents, and especially, the activity of aphidicolin was suppressed under acidic conditions. These results suggested that screening under acidic conditions would be useful for developing new chemotherapeutic reagents.

Trilostane, an inhibitor of 3β-hydroxysteroid dehydrogenase, has an agonistic activity on androgen receptor in human prostate cancer cells - Corrected Proof

2010-06-18

Abstract: The intracellular androgen metabolism and cell activity in prostate cancer cells with mutated (LNCaP-FGC) or wild-type (VCaP) androgen receptors in the presence of trilostane, an inhibitor of 3β-hydroxysteroid dehydrogenase, were examined. Trilostane suppressed the intracellular production of androstenedione, testosterone, and dihydrotestosterone from dehydroepiandrosterone in LNCaP-FGC cells. In both LNCaP-FGC and VCaP cell types, the prostate-specific antigen (PSA) levels in media were increased by trilostane alone in a concentration-dependent manner. Both cells pretreated with trilostane showed a dose-dependent decrease in PSA production with bicalutamide (P<0.001). Trilostane should be used with particular concern when treating prostate cancer.

A small oxazine compound as an anti-tumor agent: A novel pyranoside mimetic that binds to VEGF, HB-EGF, and TNF-α - Corrected Proof

2010-06-18

Abstract: A novel pyranoside mimetic compound, DMBO (2-(2,6-difluorophenyl)-5-(4-methoxyphenyl)-1-oxa-3-azaspiro[5.5]undecane), was designed and synthesized. The sugar mimicking behavior of DMBO was addressed by its ability to bind several growth factors/cytokines such as vascular endothelial growth factor (VEGF), heparin-binding epidermal growth factor-like growth factor (HB-EGF), and tumor necrosis factor (TNF)-α as demonstrated by the recently developed surface plasmon resonance assay. DMBO exhibited strong anti-proliferation activity in vitro against tumor cells including a highly metastatic murine osteosarcoma cell line LM8G7 that secretes VEGF as well as two human ovarian cell lines, OVSAHO and SKOV-3, which secrete TNF-α and HB-EGF respectively. Furthermore, DMBO inhibited the metastatic activity to the mouse liver of LM8G7 cells injected from a lateral tail vein, and affected the heparan-degrading activity of LM8G7 cells. Here, we report that DMBO acts as a human heparanase inhibitor in vitro possibly as a substrate mimetic. DMBO also inhibited the migration and invasion of LM8G7 cells and angiogenic events such as endothelial cell proliferation, migration and capillary tube-like formation in vitro. More prominently, the administration of DMBO with heparin resulted in synergistic anti-tumor effects in mouse modelofosteosarcoma. These preclinical data shows the potential anti-cancer effects of DMBO.

Microsatellite instability with promoter methylation and silencing of hMLH1 can regionally occur during progression of gastric carcinoma - Corrected Proof

2010-06-18

Abstract: Microsatellite instability (MSI) is known to result from inactivation of mismatch repair genes largely by promoter methylation. However, the methylation usually accumulates time-dependently. To know whether MSI can be acquired later in tumorigenesis, we examined intratumoral heterogeneity of MSI and promoter methylation of hMLH1 after immunohistochemical screening for heterogeneous expression of hMLH1 in 55 cases of gastric carcinomas. We demonstrated for the first time that MSI-H can develop from MSI-L or the absence of MSI due to time-dependent accumulation of DNA methylation during progression of early-stage gastric carcinomas. The resultant replication errors may play a role in enhancing invasive activity.