Cancer Letters - Articles in Press

TP53, EGFR, and KRAS mutations in relation to VHL inactivation and lifestyle risk factors in renal-cell carcinoma from central and eastern Europe - Corrected Proof

2010-02-08

Abstract: Renal-cell carcinomas (RCC) are frequent in central and eastern Europe and the reasons remain unclear. Molecular mechanisms, except for VHL, have not been much investigated. We analysed 361 RCCs (334 clear-cell carcinomas) from a multi-centre case-control study for mutations in TP53 (exons 5–9 in the whole series and exons 4 and 10 in a pilot subset of 60 tumours) and a pilot 50 tumours for mutations in EGFR (exons 18–21) or KRAS (codon 12) in relation to VHL status. TP53 mutations were detected in 4% of clear-cell cases, independently of VHL mutations. In non-clear-cell carcinomas, they were detected in 11% of VHL-wild-type tumours and in 0% of tumours with VHL functional mutations. No mutations were found in EGFR or KRAS. We conclude that mutations in TP53, KRAS, or EGFR are not major contributors to the RCC development even in the absence of VHL inactivation. The prevalence of TP53 mutations in relation to VHL status may differ between clear-cell and other renal carcinomas.

Synergistic antitumor effect of TRAIL in combination with sunitinib in vitro and in vivo - Corrected Proof

2010-02-08

Abstract: The present data showed that sunitinib potentiated the in vitro and in vivo anticancer capabilities of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), also known as Apo2 ligand. Interactions between sunitinib and TRAIL were examined in colon cancer SW620 cells and lung cancer 95-D cells. The average combination index (CI) values of the anti-proliferation abilities on each cancer cell line were less than 1.0, demonstrating the synergism of the combination of sunitinib and TRAIL. Western blot experiments indicated that TRAIL and sunitinib synergistically enhanced apoptosis by simultaneously activating the extrinsic and intrinsic pathways. The decrease in the expression levels of anti-apoptotic proteins cFLIP, XIAP and Mcl-1 were probably involved in this apoptosis enhancement. Furthermore, treatment of colon cancer SW620-bearing nude mice with sunitinib plus TRAIL resulted in more significant tumor growth inhibition (52.8%), comparing with the moderate inhibition in TRAIL-treated (35.3%) or sunitinib-treated groups (26.7%) (p<0.05). These results indicate that the combination of TRAIL with sunitinib seems highly encouraging and warrants further investigation in a clinical setting.

Phosphorylated c-Jun NH2-terminal kinase is overexpressed in human papillary thyroid carcinomas and associates with lymph node metastasis - Corrected Proof

Xiao Wang, Lan Chao, Junhui Zhen, Liansheng Chen, Guohui Ma, Xin Li — 2010-02-08

Abstract: To evaluate the associations of phosphorylated c-Jun NH2-terminal kinase (p-JNK) expression with clinicopathological features in patients with papillary thyroid carcinoma, p-JNK expression were immunohistochemically measured in 121 thyroid samples. p-JNK was overexpressed in papillary thyroid carcinomas with respect to matched nontumorous tissues (P=0.000), which was supported by western blot analysis. Increased p-JNK expression was significantly associated with the presence of lymph node metastases (P=0.001) and advanced TNM stages (P=0.02). Furthermore, p-JNK expression was positively correlated with osteopontin (OPN) expression (r=0.58, P<0.001). Activation of p-JNK may play a role in the carcinogenesis and lymph node metastasis of papillary thyroid carcinoma, and may be a molecular target for therapeutic intervention.

Pem renders tumor cells resistant to apoptotic cell death induced by a CD8+ T cell-mediated immune response or anticancer drug treatment - Corrected Proof

2010-02-08

Abstract: Pem, a member of homeobox genes, is an oncofetal gene which is preferentially expressed in reproductive tissues and in multiple tumor cell lines. However, the function of Pem in tumor cell lines has not been elucidated. Herein we report that the ectopic expression of Pem in TC-1, a human papillomavirus type 16 (HPV-16) E7-expressing surrogate cervical tumor cell line, demonstrated a significant increase in extracellular signal-regulated kinase (ERK) activity and multiple resistance to various apoptotic pressures from an E7-specific CD8+ T cell-mediated immune response and anticancer drug treatment. The observed resistance to apoptotic death of the Pem-over-expressing TC-1 tumor cells (TC-1/Pem) was associated with the down-regulation of a pro-apoptotic molecule, such as BIM, and up-regulation of an anti-apoptotic molecule, such as Bcl-2 protein, which mediated ERK activation. We also observed that the intratumoral injection of an ERK inhibitor enhanced the therapeutic efficacy of E7-specific CD8+ T cell adoptive transfer or anticancer drug treatment against the resistant TC-1/Pem tumor. This is the first evidence demonstrating an association between Pem and a signaling pathway, namely the ERK-mediated survival signal transduction pathway. Thus, our data indicate that activation of the ERK pathway represents a new mechanism of Pem-mediated multiple resistances and the present research will contribute to the development of a novel strategy in cancer therapy against Pem-over-expressing tumor cells.

Dihydroartemisinin inactivates NF-κB and potentiates the anti-tumor effect of gemcitabine on pancreatic cancer both in vitro and in vivo - Corrected Proof

2010-02-05

Abstract: Gemcitabine is currently the best known chemotherapeutic option available for pancreatic cancer, but the tumor returns de novo with acquired resistance over time, which becomes a major issue for all gemcitabine-related chemotherapies. In this study, for the first time, we demonstrated that dihydroartemisinin (DHA) enhances gemcitabine-induced growth inhibition and apoptosis in both BxPC-3 and PANC-1 cell lines in vitro. The mechanism is at least partially due to DHA deactivates gemcitabine-induced NF-κB activation, so as to decrease tremendously the expression of its target gene products, such as c-myc, cyclin D1, Bcl-2, Bcl-xL. In our in vivo studies, gemcibabine also manifested remarkably enhanced anti-tumor effect when combined with DHA, as manifested by significantly increased apoptosis, as well as decreased Ki-67 index, NF-κB activity and its related gene products, and predictably, significantly reduced tumor volume. We concluded that inhibition of gemcitabine-induced NF-κB activation is one of the mechanisms that DHA dramatically promotes its anti-tumor effect on pancreatic cancer.

Proteasome inhibition: A new therapeutic strategy to cancer treatment - Corrected Proof

2010-02-04

Abstract: The ubiquitin–proteasome system is a major pathway for protein degradation. Targeting this pathway using proteasome inhibitors represents a novel approach for the treatment of cancer. Proteasome inhibitors lower cell proliferation and induce apoptosis in solid and hematologic malignancies through multiple mechanisms, including stabilization of cell cycle regulators and pro-apoptotic factors, stimulation of bone morphogenetic protein signaling, inhibition of protein translation, and sensitization to ligand-induced apoptosis. In this connection, proteasome inhibition activates macroautophagy, a compensatory protein degradation system, as well as other pro-survival signaling pathways. Inhibition of these auto-protective responses sensitizes cancer cells to the anti-proliferative effects of proteasome inhibitors.

Apoptosis and lysosome membrane permeabilization induction on breast cancer cells by an anticarcinogenic Bowman–Birk protease inhibitor from Vigna unguiculata seeds - Corrected Proof

Graziella Anselmo Joanitti, Ricardo Bentes Azevedo, Sonia Maria Freitas — 2010-02-04

Abstract: In this work, we report the effects of a Bowman–Birk protease inhibitor, the Black-Eyed Pea Trypsin/Chymotrypsin Inhibitor – BTCI, purified from Vigna unguiculata seeds, on the MCF-7 breast cancer cells. The treatment of MCF-7 with 200μM BTCI for 72h induced significant reduction of the cell viability and proliferation (arrest in S and G2/M phase). These cytostatic effects were accompanied by acute morphological modifications including the alteration of the nuclear morphology, plasma membrane fragmentation, cytoplasm disorganization, presence of double-membrane vesicles, mitochondrial swelling, and an increase in the size of lysosomes. Significative DNA fragmentation, annexin-V+ cell number increase, mitochondrial membrane potential reduction, and cytoplasm acidification were also detected. All together, these cytostatic and cytotoxic results point out to BTCI-induced apoptosis cell death associated with severe cell morphological alterations and lysosome membrane permeabilization. Our study confirms the anticarcinogenic potential of Bowman–Birk protease inhibitors and identifies BTCI as a promising tool for drug developments aimed at the treatment of breast cancer.

Chrysin sensitizes tumor necrosis factor-α-induced apoptosis in human tumor cells via suppression of nuclear factor-kappaB - Corrected Proof

Xin Li, Qing Huang, Choon-Nam Ong, Xing-Fen Yang, Han-Ming Shen — 2010-02-04

Abstract: Chrysin (5,7-dihydroxyflavone) is a natural flavonoid commonly found in many plants. The anti-cancer property of chrysin has been demonstrated although the molecular mechanisms remain to be further elucidated. In the present study, we found that, pretreatment with chrysin greatly sensitized various human cancer cells to tumor necrosis factor-alpha (TNFα)-induced apoptosis. In the search of the molecular mechanisms responsible for the sensitization effect of chrysin, we discovered that such sensitization is closely associated with the inhibitory effect of chrysin on TNFα-mediated nuclear transcription factor-kappaB (NF-κB) activation. Pretreatment with chrysin inhibited TNFα-induced degradation of Inhibitor of kappaB (IκB) protein and subsequent nuclear translocation of p65. As a result, chrysin suppressed the expression of NF-κB-targeted anti-apoptotic gene, c-FLIP-L. The role of c-FLIP-L was further confirmed by its ectopic expression, which significantly protected cell death induced by combined treatment with chrysin and TNFα. Data from this study thus reveal a novel function of chrysin and enhance the value of chrysin as an anti-cancer agent.

Expression profiling identifies epoxy anthraquinone derivative as a DNA topoisomerase inhibitor - Corrected Proof

2010-02-04

Abstract: To discover novel drugs for neuroblastoma treatment, we have previously screened a panel of drugs and identified 30 active agents against neuroblastoma cells. Here we performed microarray gene expression analysis to monitor the impact of these agents on a neuroblastoma cell line and used the connectivity map (cMAP) to explore putative mechanism of action of unknown drugs. We first compared the expression profiles of 10 compounds shared in both our dataset and cMAP database and observed the high connectivity scores for 7 of 10 matched drugs regardless of the differences of cell lines utilized. The screen of cMAP for uncharacterized drugs indicated the signature of Epoxy anthraquinone derivative (EAD) matched the profiles of multiple known DNA targeted agents (topoisomerase I/II inhibitors, DNA intercalators, and DNA alkylation agents) as predicted by its structure. Similar result was obtained by querying against our internal NB-cMAP (http://pob.abcc.ncifcrf.gov/cgi-bin/cMAP), a database containing the profiles of 30 active drugs. These results suggest that Epoxy anthraquinone derivative may inhibit neuroblastoma cells by targeting DNA replication inhibition. Experimental data also demonstrate that Epoxy anthraquinone derivative indeed induces DNA double-strand breaks through DNA alkylation and inhibition of topoisomerase activity. Our study indicates that Epoxy anthraquinone derivative may be a novel DNA topoisomerase inhibitor that can be potentially used for treatment of neuroblastoma or other cancer patients.

Molecular and traditional chemotherapy: A united front against prostate cancer - Corrected Proof

P. Singh, M. Yam, P.J. Russell, A. Khatri — 2010-02-01

Abstract: Castrate resistant prostate cancer (CRPC) is essentially incurable. Recently though, chemotherapy demonstrated a survival benefit (∼2months) in the treatment of CRPC. While this was a landmark finding, suboptimal efficacy and systemic toxicities at the therapeutic doses warranted further development. Smart combination therapies, acting through multiple mechanisms to target the heterogeneous cell populations of PC and with potential for reduction in individual dosing, need to be developed. In that, targeted molecular chemotherapy has generated significant interest with the potential for localized treatment to generate systemic efficacy. This can be further enhanced through the use of oncolytic conditionally replicative adenoviruses (CRAds) to deliver molecular chemotherapy. The prospects of chemotherapy and molecular-chemotherapy as single and as components of combination therapies are discussed.

Genetic alterations in a telomerase-immortalized human esophageal epithelial cell line: Implications for carcinogenesis - Corrected Proof

2010-01-21

Abstract: Ectopic expression of viral oncoproteins disrupts cellular functions and limits the value of many existing immortalization models as models for carcinogenesis, especially for cancers without definitive viral etiology. Our newly established telomerase-immortalized human esophageal epithelial cell line, NE2-hTERT, retained nearly-diploid and non-tumorigenic characteristics, but exhibited genetic and genomic alterations commonly found in esophageal cancer, including progressive loss of the p16INK4a alleles, upregulation of anti-apoptotic proteins, epithelial-mesenchymal transition, whole-chromosome 7 gain and duplicated 5q arm. Our data also revealed a novel positive regulation of p16INK4a on cyclin D1. These findings probably represent early crucial events and mechanisms in esophageal carcinogenesis.

Edaravone, a known free radical scavenger, enhances X-ray-induced apoptosis at low concentrations - Corrected Proof

2010-01-21

Abstract: Edaravone has been reported to have a radioprotective effect at high concentrations. We now report that a lower dose of edaravone enhanced X-ray-induced apoptosis of some cell lines harboring p53 wild-type status, such as MOLT-4, Nalm-6, and HepG2. The knock-down of p53 using siRNA in MOLT-4 cells abolished the radiosensitizing effect of edaravone. Enhanced phosphorylations of p53 at Ser 15 and Ser 20 and up-regulation of PUMA, a p53 target protein, were observed after X-irradiation in the presence of edaravone. We conclude that the low dose of edaravone sensitized cells to X-irradiation by promoting the p53-dependent apoptotic signaling pathway.

Tobacco carcinogen NNK transporter MRP2 regulates CFTR function in lung epithelia: Implications for lung cancer - Corrected Proof

Chunying Li, John D. Schuetz, Anjaparavanda P. Naren — 2010-01-20

Abstract: Lung cancer is the leading cause of cancer death in the United States. About 85% of all lung cancers are linked to tobacco smoke, in which more than 50 lung carcinogens have been identified and one of the most abundant is 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). The human lung epithelium constitutes the first line of defense against tobacco-specific carcinogens, in which apically-localized receptors, transporters, and ion channels in the airway may play a critical role in this native defense against tobacco smoke. Here we showed that multidrug resistance protein-2 (MRP2) and cystic fibrosis transmembrane conductance regulator (CFTR), two ATP-binding cassette (ABC) transporters, are localized to the apical surfaces of plasma membrane in polarized lung epithelial cells. We observed that there is a functional coupling between CFTR and MRP2 that may be mediated by PDZ proteins. We also observed the existence of a macromolecular complex containing CFTR, MRP2, and PDZ proteins, which might form the basis for the regulatory cooperation between these two ABC transporters. Our results have important implications for cigarette smoke-associated lung diseases (such as smoke-related emphysema, chronic obstructive pulmonary disease, and lung cancer).

Curcumin inhibits the side population (SP) phenotype of the rat C6 glioma cell line: Towards targeting of cancer stem cells with phytochemicals - Corrected Proof

Dunne Fong, Arthur Yeh, Rotem Naftalovich, Theresa Hyejeong Choi, Marion M. Chan — 2010-01-20

Abstract: The phytochemical curcumin, from the Indian spice turmeric, has many biological properties, including anti-inflammatory and anti-carcinogenic activities. We have examined the effects of curcumin on the rat C6 glioma cell line. Treated and control cells were analyzed by Hoechst 33342 dye and flow cytometry. We observed a decrease in the side population (SP) of C6 cells after daily curcumin treatment of the C6 cells. Direct incubation of curcumin to C6 cells during the Hoechst assay also decreased SP. Since SP has been associated with stem cell populations, curcumin may be a dietary phytochemical with potential to target cancer stem cells.

Induction of apoptosis by quercetin is mediated through AMPKα1/ASK1/p38 pathway - Corrected Proof

Yun-Kyoung Lee, Jin-Taek Hwang, Dae Young Kwon, Young-Joon Surh, Ock Jin Park — 2010-01-18

Abstract: Effective strategies for cancer prevention and treatment can be identified by understanding the mechanism of apoptotic pathways. In this study, we investigated the regulatory mechanism of quercetin-induced apoptosis through apoptosis signal-regulating kinase (ASK)-1 and mitogen-activated protein kinase pathways. Our results showed that quercetin increased apoptotic cell death through reactive oxygen species (ROS) generation and was responsible for ASK1 activation. Increasing ASK1 activity was accompanied by p38 activation. Interestingly, AMP-activated protein kinase (AMPK) seemed to be a critical controller of quercetin-regulated ASK1/p38 activation. Blocking AMPKα1 activity using Compound C, a synthetic inhibitor or siRNA showed that quercetin-activated ASK1 could not stimulate p38 activity. Thus, we suggested that quercetin-exerted apoptotic effects involve ROS/AMPKα1/ASK1/p38 signaling pathway, and AMPKα1 is a necessary element for apoptotic event induced by ASK1.

Lifestyle as risk factor for cancer: Evidence from human studies - Corrected Proof

Naghma Khan, Farrukh Afaq, Hasan Mukhtar — 2010-01-18

Abstract: It is increasingly appreciated that the chances of developing cancer are significantly affected by the choice of our lifestyle. There are several uncontrollable risk factors which account for the majority of cancers, but we can modify our lifestyle to reduce enhanced threat of cancer. Healthy lifestyle behaviors for cancer risk reduction include a healthy diet, weight management, regular exercise, reduction in alcohol consumption and smoking cessation. In this article, we present evidences on the association between certain lifestyle characteristics and their contribution for developing breast, prostate, lung and colon cancers, using information derived from human studies.

BRMS1 expression alters the ultrastructural, biomechanical and biochemical properties of MDA-MB-435 human breast carcinoma cells: An AFM and Raman microspectroscopy study - Corrected Proof

2010-01-18

Abstract: Restoring BReast cancer Metastasis Suppressor 1 (BRMS1) expression suppresses metastasis in MDA-MB-435 human breast carcinoma cells at ectopic sites without affecting tumor formation at orthotopic site in the body. BRMS1 expression induces many phenotypic alterations in 435 cells such as cell adhesion, cytoskeleton rearrangement, and the down regulation of epidermal growth factor receptor (EGFR) expression. In order to better understand the role of cellular biomechanics in breast cancer metastasis, the qualitative and quantitative detection of cellular biomechanics and biochemical composition is urgently needed. In the present work, using atomic force microscopy (AFM) and fluorescent microscopy we revealed that BRMS1 expression in 435 cells induced reorganization of F-actin and caused alteration in cytoarchitectures (cell topography and ultrastructure). Results from AFM observed increase in biomechanical properties which include cell adhesion, cellular spring constant, and Young’s modulus in 435/BRMS1 cells. Raman microspectroscopy showed weaker vibrational spectroscopic bands in 435/BRMS1 cells, implying decrease in concentration of cellular biochemical components in these cells. This was despite the similar spectral patterns observed between 435 and 435/BRMS1 cells. This work demonstrated the feasibility of applying AFM and Raman techniques for in situ measurements of the cellular biomechanics and biochemical components of breast carcinoma cells. It provides vital clues in understanding of the role of cellular biomechanics in cancer metastasis, and further the development of new techniques for early diagnosis of breast cancer.

Lunasin peptide purified from Solanum nigrum L. protects DNA from oxidative damage by suppressing the generation of hydroxyl radical via blocking fenton reaction - Corrected Proof

Jin Boo Jeong, Ben O. De Lumen, Hyung Jin Jeong — 2010-01-18

Abstract: Oxidative DNA damage is the most critical factor implicated in carcinogenesis and other disorders. However, the protective effects of lunasin against oxidative DNA damage have not yet reported. In this study, we report here the protective effect of lunasin purified from Solanum nigrum L. against oxidative DNA. Lunasin protected DNA from the oxidative damage induced by Fe2+ ion and hydroxyl radical. To better understand the mechanism for the protective effect of lunasin against DNA damage, the abilities to chelate Fe2+, scavenge the generated hydroxyl radical and block the generation of hydroxyl radical were evaluated. Although it did not scavenge generated hydroxyl radical, lunasin blocked the generation of hydroxyl radical by chelating Fe2+ ion.We conclude that lunasin protects DNA from oxidation by blocking fenton reaction between Fe2+ and H2O2 by chelating Fe2+ and that consumption of lunasin may play an important role in the chemoprevention for the oxidative carcinogenesis.

Activation of 5-lipoxygenase is required for nicotine mediated epithelial–mesenchymal transition and tumor cell growth - Corrected Proof

2010-01-11

Abstract: Nicotine is shown to be one of the carcinogenic agents for gastric cancer. Perturbation of epithelial–mesenchymal transition (EMT) results in loss of intracellular adhesions leading to tumor progression. In this study, we examined the underlying mechanism of the long-term effects of nicotine on tumor progression in human gastric cancer cells. Nicotine activated 5-lipoxygenase (5-LOX) in three gastric cancer cell lines (MKN-45, MKN-28 and AGS). Cells treated with nicotine dose- and time-dependently induced cell proliferation, invasion and suppressed apoptosis. In addition, cell cycle progression analysis revealed that activation of 5-LOX modulated the G1/S phase transition regulatory proteins and caused cell proliferation. MK886 (5-LOX activating protein inhibitor) mediated the induction of apoptosis by elevation of caspase-3 and Bax/Bcl2 ratio. Abrogation of 5-LOX repressed featured molecular markers of EMT (inactivation of E-cadherin and activation of transcriptional repressor Snail). Blockade of 5-LOX signaling resulted in downregulation of cyclin D1, matrix metalloproteinase (MMP-7, -9), urokinase plasminogen activator (uPA) and its receptor (uPAR), and pro-apoptotic proteins. Furthermore, suppression of Snail and induction of E-cadherin is extracellular signal-regulated kinase (Erk)-dependent. Thus, we conclude that the promotion effect of nicotine on cancer cell progression and EMT is mediated by Erk/5-LOX signaling pathway.

GHRH antagonists reduce the invasive and metastatic potential of human cancer cell lines in vitro - Corrected Proof

2010-01-11

Abstract: We investigated the effect of a GHRH antagonist, MIA-602on the metastatic cascade in vitro of three human cancers, DBTRG-05 glioblastoma, MDA-MB-468 estrogen-independent breast, and ES-2 clear cell ovarian cancer. GHRH receptors and their main splice variant, SV1 were detected on all three cell lines. After treatment with MIA-602, the cell viability decreased significantly, significant inhibition of cell invasion was observed and the release of MMPs was significantly decreased. The attachment of cancer cells to fibronectin and matrigel was severely hindered. Wound-healing experiments demonstrated a reduced cellular motility in all three cell lines. The upregulation of caveolin-1 and E-cadherin,and thepowerful downregulation of NF-κB and β-catenin was detected. Our study suggests that the clinical application of highly potent GHRH antagonists in cancer therapy would be desirable since they inhibit proliferation and metastasis development as well.

Suberoylanilide hydroxamic acid limits migration and invasion of glioma cells in two and three dimensional culture - Corrected Proof

Zhihua An, Christian B. Gluck, Megan L. Choy, Laura J. Kaufman — 2010-01-08

Abstract: High grade gliomas are aggressive cancers that are not well addressed by current chemotherapies, in large measure because these drugs do not curtail the diffuse invasion of glioma cells into brain tissue surrounding the tumor. Here, we investigate the effects of suberoylanilide hydroxamic acid (SAHA) on glioma cells in 2D and 3D in vitro assays, as SAHA has previously been shown to significantly increase apoptosis, decrease proliferation, and interfere with migration in other cell lines. We find that SAHA has significant independent effects on proliferation, migration, and invasion. These effects are seen in both 2D and 3D culture. In 3D culture, with glioma spheroids embedded in collagen I matrices, SAHA independently limits both glioma invasion and the reorganization of the tumor surroundings that usually proceeds such invasion. The decreased matrix reorganization and invasion is not accompanied by decreased production or activity of matrix-metalloproteases but instead may be related to increased cell–cell adhesion.

Characterization of a humanized anti-CD20 antibody with potent antitumor activity against B-cell lymphoma - Corrected Proof

2010-01-07

Abstract: Despite the effectiveness of the anti-CD20 chimeric antibody (mAb), rituximab, in treating B-cell lymphomas, its efficacy remains variable and often modest. In this study, a humanized anti-CD20 antibody, hu8E4, was generated by complementarity-determining region grafting method. Hu8E4 was as effective as rituximab in mediating antibody-dependent cellular cytotoxicity and inducing apoptosis in B-lymphoma cells, but it exhibited much more potent complement-dependent cytotoxicity than rituximab. Immunotherapeutic studies showed that hu8E4 was significantly more effective than rituximab in prolonging the survival of severe combined immunodeficient mice bearing human B-cell lymphomas, suggesting that it might be a promising therapeutic agent for B-cell lymphomas.

Biomarkers for predicting the sensitivity of cancer cells to TRAIL-R1 agonistic monoclonal antibody - Corrected Proof

Shinsuke Araki, Yusuke Nakayama, Akira Hori, Koji Yoshimura — 2010-01-07

Abstract: Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and an agonistic monoclonal antibody to TRAIL-R1 (TRAIL-R1 mAb) induce apoptosis and show anti-proliferative activity in vitro and in vivo. However, some TRAIL-R1-expressing cell lines are not sensitive to either TRAIL-R1 mAb or TRAIL. We have identified four genes (STK17B, SP140L, CASP8, and AIM1) whose expression levels differ significantly between TRAIL-R1 mAb-sensitive and resistant cell lines. Using the expression levels of these genes, we predicted TRAIL-R1 mAb and TRAIL sensitivity in our test cell lines with 75% (9/12) and 84% (21/25) accuracy, respectively. Knockdown of STK17B in TRAIL-R1 mAb-sensitive cells augmented Bcl-2 expression and suppressed TRAIL-R1 mAb-induced apoptosis. Our results may be useful for predicting the response of cancers to TRAIL-agonistic drugs in the clinic.

Tephrosin induces internalization and degradation of EGFR and ErbB2 in HT-29 human colon cancer cells - Corrected Proof

2010-01-07

Abstract: Inactivation of epidermal growth factor receptor (EGFR) family members are prime targets for cancer therapy. Here, we show that tephrosin, a natural rotenoid which has potent antitumor activities, induced internalization of EGFR and ErbB2, and thereby induced degradation of the receptors. Treatment of HT-29 cells with tephrosin inhibited both the ligand-induced and constitutive phosphorylation of EGFR, ErbB2 and ErbB3, and concomitantly suppressed the activation of the downstream signaling molecules such as Akt and Erk1/2 mitogen-activated protein kinase (MAPK). Tephrosin caused internalization of EGFR and ErbB2 into vehicles, which resulted in degradation of the receptors. This degradation was blocked by the lysosomal inhibitor, chloroquine. We also showed that tephrosin induced apoptosis. Tephrosin did not induce the proteolytic processing of caspase-3 and poly(ADP-ribose) polymerase (PARP), but did nuclear translocation of apoptosis-inducing factor (AIF), suggesting that tephrosin may induce caspase-independent apoptosis. These findings provide the first evidence that tephrosin could exert antitumor effects by inducing internalization and degradation of inactivated EGFR and ErbB2 in human colon cancer cells.

Diosgenin, a steroidal saponin, inhibits STAT3 signaling pathway leading to suppression of proliferation and chemosensitization of human hepatocellular carcinoma cells - Corrected Proof

2010-01-06

Abstract: Constitutive activation of STAT3 has been shown in several human cancers and transformed cell lines including hepatocellular carcinoma (HCC). In the present report, we investigated whether diosgenin, a steroidal saponin isolated from fenugreek can modulate the STAT3 signaling pathway. We found that diosgenin inhibited both constitutive and inducible activation of STAT3 with no effect on STAT5. The activation of c-Src, JAK1 and JAK2 implicated in STAT3 activation, were also suppressed by this saponin. Pervanadate reversed the diosgenin-induced downregulation of STAT3, suggesting the involvement of a protein tyrosine phosphatase. Indeed, we found that diosgenin can induce the expression of Src homology 2 phosphatase 2 (SH-PTP2) that correlated with downregulation of constitutive STAT3 activation. Diosgenin also downregulated the expression of various STAT3-regulated gene products, inhibited proliferation and potentiated the apoptotic effects of paclitaxel and doxorubicin. Overall, these results suggest that diosgenin is a novel blocker of the STAT3 activation pathway, with a potential role in the treatment of HCC and other cancers.

Inhibition of growth and motility of human A549 lung carcinoma cells by a recombined vascular basement membrane derived peptide - Corrected Proof

Cheng-kun Wang, Jian-guo Cao, Bo Peng, Yi-xue Gu, Guo-pei Zheng, Zhi-min He — 2010-01-06

Abstract: We have previously constructed a recombined vascular basement membrane derived multifunctional peptide (rVBMDMP) which can inhibit tumor growth. The aim of this study is to explore the effects and mechanisms of rVBMDMP on growth and motility/invasion in human A549 lung carcinoma cells. The effect of rVBMDMP on A549 cell viability was determined by MTT assay while the motility/invasion was measured by scratch and transwell assays. Molecules that responded to rVBMDMP treatment of A549 cells were explored using the high-throughput Cancer Pathway Finder cDNA Microarray. We identified 16 genes that were up-regulated, including GZMA, ITG αV, MCAM and Kiss1 and 21 genes that were down-regulated, including uPA, uPAR, CDC25A, IGF1 and FGF2. Selective differentially expressed genes were further analyzed by real-time quantitative PCR and Western blot analysis. These findings contribute to the understanding of the molecular mechanisms mediating rVBMDMP action, and suggest that rVBMDMP is a promising novel agent for the treatment of human lung carcinoma.

RNA polymerase – An important molecular target of triptolide in cancer cells - Corrected Proof

Jingxuan Pan — 2010-01-04

Abstract: Triptolide, a diterpenoid triepoxide, is the key biological component of Tripterygium wilfordii Hook. f. which was used in traditional Chinese medicine for centuries to treat inflammation and autoimmune diseases. Triptolide has shown potent activity in not only anti-inflammation and immune modulation, but also antiproliferative and proapoptotic activity in many different types of cancer cells. However, for a long time, the precise molecular target(s) of triptolide have remained elusive. Recently, several groups discovered that triptolide inhibited the activity of RNA polymerase. This review will focus on these breakthrough findings about the molecular target of triptolide and its implications for targeted-cancer therapeutics.

Induction of neuronal apoptosis inhibitory protein expression in response to androgen deprivation in prostate cancer - Corrected Proof

2009-12-31

Abstract: A mechanism for survival of prostate cancer cells in an androgen-deprived environment remains elusive. Here, we find that expression of neuronal apoptosis inhibitory protein (NAIP) was significantly increased in vivo and in vitro in response to androgen deprivation therapy (ADT). Increased expression of NAIP corresponded to increased DNA-binding activity of NF-κB that physically associated to previously uncharacterized κB-like sites in the NAIP locus. Importantly, expression of NAIP was significantly increased (p=0.04) in clinical samples of prostate cancer from patients receiving ADT. Expression of NAIP may be associated with enhanced survival of prostate cancer in response to castration.

Detection of chronic lymphocytic leukemia cell surface markers using surface enhanced Raman scattering gold nanoparticles - Corrected Proof

2009-12-30

Abstract: Selective targeting and detection of a hematologic malignancy, chronic lymphocytic leukemia, using surface enhanced Raman scattering (SERS) gold nanoparticles is reported. The functional nanoparticles were composed of a gold core onto which an optical reporter dye was adsorbed, protected from aggregation by grafted polyethyleneglycol, and targeted to CD19 antigen by antibodies. The signals were detected by dark-field microscopy and Raman spectrometry. The observation that the Raman signals are not disrupted by several traditional pathology stains indicates advantages over fluorescence methods.

p21Cip1 Confers resistance to imatinib in human chronic myeloid leukemia cells - Corrected Proof

2009-12-30

Abstract: Imatinib is a Bcr-Abl inhibitor used as first-line therapy of chronic myeloid leukemia (CML). p21Cip1, initially described as a cell cycle inhibitor, also protects from apoptosis in some models. We describe that imatinib down-regulates p21Cip1 expression in CML cells. Using K562 cells with inducible p21 expression and transient transfections we found that p21 confers partial resistance to imatinib-induced apoptosis. This protection is not related to the G2-arrest provoked by p21, a decrease in the imatinib activity against Bcr-Abl or a cytoplasmic localization of p21. The results suggest an involvement of p21Cip1 in the response to imatinib in CML.

Targeting aminopeptidase N (APN/CD13) with cyclic-imide peptidomimetics derivative CIP-13F inhibits the growth of human ovarian carcinoma cells - Corrected Proof

2009-12-30

Abstract: Aminopeptidase N (APN/CD13) is an essential peptidase involved in the process of tumor growth, metastasis and angiogenesis. Inhibition of APN/CD13 may be an effective strategy for cancer treatment. CIP-13F is a cyclic-imide peptidomimetics compound designed to fit the active pockets S1 and S′1 of APN/CD13 that act in tumor proliferation. Our aim in this study was to evaluate the efficacy of CIP-13F as a candidate compound for cancer treatment. The experiments were performed on the human ovarian carcinoma (OVCA) ES-2 and HRA cell lines, which have high and low levels of APN/CD13 respectively. CIP-13F significantly blocked APN/CD13 activity on the surface of ES-2 cells as measured by quantitating the enzymatic cleavage of the substrate l-leucine-p-nitroanilide. CIP-13F effectively inhibited ES-2 cell growth and migration without significant cytotoxic effect. In contrast, CIP-13F did not significantly inhibit HRA cell growth, indicating that CIP-13F may inhibit ES-2 cell growth via suppression of APN/CD13. The suppression of APN/CD13 was also observed by using the assays of flow cytometry and Western blot analysis. Further, the inhibitory effects of CIP-13F on APN/CD13 and on ES-2 proliferation were supported by the induction of ES-2 apoptosis. CIP-13F-treated ES-2 cells resulted apoptotic characteristics, such as induction of externalization of phosphatidylserine and DNA laddering fragment. The activation of caspase-3 and poly ADP-ribose polymerase (PARP) was also enhanced. The inhibitory effects of CIP-13F on APN/CD13 expression and on ES-2 proliferation were confirmed in mice bearing ES-2 xenografts. CIP-13F delayed the growth of ES-2 xenografts in mice after 2 weeks of vena caudalis injection. These results suggest that CIP-13F has a high inhibitory effect on the growth of OVCA cells via decreasing the activity and expression of APN/CD13.

ATM- and ATR-mediated response to DNA damage induced by a novel camptothecin, ST1968 - Corrected Proof

Valentina Zuco, Valentina Benedetti, Franco Zunino — 2009-12-30

Abstract: DNA damage response and checkpoint activation are expected to influence the sensitivity to DNA-damaging agents. This study was designed to investigate the DNA damage response to the novel camptothecin, ST1968, in two tumor cell lines with a different biological background (A2780 and KB), which underwent distinct cell cycle perturbations and cell death modalities. Following treatment with the camptothecin or ionizing radiation, both inducing double-strand DNA breaks, the ovarian carcinoma A2780 cells exhibited activation of the ATM-Chk2 pathway and early induction of apoptosis. In contrast, the squamous carcinoma KB cells exhibited activation of ATR-Chk1 pathway, a persistent G2/M-phase arrest, cellular senescence, mitotic catastrophe and delayed apoptosis, suggesting a defective ATM pathway. The cellular response to UV-induced DNA damage, which activates ATR-Chk1 pathway, was similar in the two cell lines exhibiting early apoptosis induction. Inhibition of ATM in A2780 cells, resulting in reduced phosphorylation of Chk2, enhanced ST1968-induced apoptosis, but had no effect in KB cells. The susceptibility to camptothecin-induced apoptosis of A2780 cells was likely p53-dependent but not related to the activation of the ATM pathway. In contrast, the inhibition of Chk1 enhanced apoptosis response in KB cell but not in A2780. Thus, depending on the biological context, the camptothecin activated ATM-Chk2 or ATR-Chk1 pathways, both having a protective role. In conclusion, our results are consistent with the interpretation that the modality of cell death response is not the critical determinant of sensitivity to camptothecins, and support the interest of inhibition of checkpoint kinases to improve the efficacy of camptothecins.

Moscatilin, a bibenzyl derivative from the India orchid Dendrobrium loddigesii, suppresses tumor angiogenesis and growth in vitro and in vivo - Corrected Proof

2009-12-28

Abstract: Attacking angiogenesis is considered an effective strategy for controls the expansion and metastasis of tumors and other related-diseases. The aim of this study was to assess the effects of moscatilin, a bibenzyl derivative, on VEGF and bFGF-induced angiogenesis in cultured human umbilical vein endothelial cells (HUVECs) in vitro and in vivo. Moscatilin significantly inhibited growth of lung cancer cell line A549 (NSCLC) and suppressed growth factor-induced neovascularization. In addition, VEGF- and bFGF-induced cell proliferation, migration, and tube formation of HUVECs was markedly inhibited by moscatilin. Western blotting analysis of cell signaling molecules indicated that moscatilin inhibited ERK1/2, Akt, and eNOS signaling pathways in HUVECs. These results suggest that inhibition of angiogenesis by moscatilin may be a major mechanism in cancer therapy.

Human papillomavirus and p16 expression in inverted papillomas of the urinary bladder - Corrected Proof

2009-12-28

Abstract: Human Papillomaviruses (HPVs) have been found in association with benign and malignant growth of epithelia. The cell cycle inhibitor p16Ink4a has been shown to be overexpressed in HPV-positive cervical pre-malignant and malignant lesions, probably as a result of pRB targeting by the viral E7 protein. Inverted papillomas of the urinary bladder are epithelial tumors considered to be of benign nature. In this report we analyze the expression of p16Ink4a and the presence of HPV sequences in inverted papillomas and in non-tumoral bladder controls. Our results show no association of HPV infection and inverted papillomas. Further, no correlation between p16 overexpression and HPV positivity was found. We conclude that HPV does not play an indispensable role in the development of urinary bladder inverted papillomas and that overexpression of p16Ink4a does not correlate with HPV infection in these tumors.

Fanconi Anemia pathway heterogeneity revealed by cisplatin and oxaliplatin treatments - Corrected Proof

Lisa A. Kachnic, Li Li, Loreen Fournier, Henning Willers — 2009-12-25

Abstract: Genetic or epigenetic inactivation of the pathway formed by the Fanconi Anemia (FA) proteins occurs in several cancer types, including head and neck squamous cell carcinomas (HNSCC), rendering the affected tumors potentially hypersensitive to DNA crosslinking agents. However, the cytotoxicity of other commonly used cancer therapeutics in cells with FA pathway defects remains to be defined. Here, we focused on the effects of cisplatin and oxaliplatin in a panel of HNSCC and fibroblast cell lines. We found that FANCC- and FANCD2-mutant cells were unexpectedly more sensitive to platinum drugs than FANCA-mutant cells, and mono-ubiquitination of FANCD2, which is mediated by the FANCA and FANCC containing FA core complex was not required for platinum resistance. Interestingly, platinum hypersensitivity could be dissociated from mitomycin C hypersensitivity suggesting different underlying mechanisms. FANCD2 or RAD51 subnuclear foci were not useful as biomarkers of platinum hypersensitivity of FANCC/FANCD2-mutant cells. Our data add to an emerging body of evidence indicating that the FA pathway is not linear and that several protein subcomplexes with different functions exist. It will be important to establish biomarkers that can predict the sensitivity of tumors with specific FA defects to chemotherapeutic agents.

HMGB2 stabilizes p53 by interfering with E6/E6AP-mediated p53 degradation in human papillomavirus-positive HeLa cells - Corrected Proof

Daekyun Lee, Jung-Hee Kwon, Eui Ho Kim, Eung-Sam Kim, Kwan Yong Choi — 2009-12-25

Abstract: We investigated the effect of HMGB2 on the stability of p53 protein in HeLa cells. Overexpression of HMGB2 led to accumulation of the p53 protein, whereas HMGB2 knockdown with siRNA resulted in a substantial decrease in the p53 protein level. The HMGB2-dependent increase of p53 stability was specific for HPV-positive HeLa cells as HCT116 and MCF7 cell lines did not demonstrate this response. Co-expression of HMGB2 and HPV E6 prevented HPV E6 protein-mediated ubiquitination and degradation of p53. FACS analysis exhibited that HeLa cells transfected with HMGB2 displayed decreased cell proliferation, with a concomitant increase of the p53 protein and arrest of the cell cycle, predominantly in G1 phase. Our findings collectively suggest that HMGB2 could stabilize p53 by interfering with E6/E6AP-mediated p53 degradation in HPV-positive HeLa cells.

Cross-talk between miRNA and Notch signaling pathways in tumor development and progression - Corrected Proof

2009-12-21

Abstract: Notch signaling pathways are known to regulate many cellular processes, including cell proliferation, apoptosis, migration, invasion, and angiogenesis, and is one of the most important signaling pathway during normal development. Recently, emerging evidences suggest that microRNAs (miRNAs) can function as key regulators of various biological and pathologic processes during tumor development and progression. Notch signaling has also been reported to be regulated through cross-talk with many pathways and factors where miRNAs appears to play a major role. This article will provide a brief overview of the published evidences for the cross-talks between Notch and miRNAs. Further, we summarize how targeting miRNAs by natural agents could become a novel and safer approach for the prevention of tumor progression and treatment.

HA14-1 sensitizes TNF-α-induced apoptosis via inhibition of the NF-κB signaling pathway: Involvement of reactive oxygen species and JNK - Corrected Proof

2009-12-21

Abstract: Nuclear factor-kappa B (NF-κB) activation by tumor necrosis factor-alpha (TNF-α) attenuates the TNF-α-induced apoptosis pathway. Thus, blockage of NF-κB activity may improve the anti-cancer activity of TNF-α. HA14-1 induces apoptosis in various human cancer cells, and the molecular mechanisms of this action remain to be fully characterized. The present study evaluated the involvement of NF-κB, reactive oxygen species (ROS), and c-Jun N-terminal kinase (JNK) in the effects of HA14-1 by examining the sensitization effect on TNF-α-induced apoptosis in human leukemia cells. Such sensitization is closely associated with the inhibitory effect of HA14-1 on TNF-α-mediated NF-κB activation. HA14-1 suppressed NF-κB activation through inhibition of phosphorylation and degradation of IκBα. This inhibition was correlated with suppression of NF-κB-dependent gene products (c-myc, cyclin D1, cox-2, and IAP-1). Additionally, the present findings provide evidence of a critical role of ROS accumulation induced by HA14-1 in TNF-α-induced apoptosis. Moreover, HA14-1 also markedly sustained TNF-α-mediated JNK activation. A specific JNK inhibitor abolished the sensitization effect of HA14-1 on TNF-α-induced apoptosis. Taken together, these results indicate that ROS and JNK represent important signals in HA14-1 sensitization in TNF-α-induced apoptosis.

Hypoxia suppresses chemotherapeutic drug-induced p53 Serine 46 phosphorylation by triggering HIPK2 degradation - Corrected Proof

Jutta Moehlenbrink, Nadja Bitomsky, Thomas G. Hofmann — 2009-12-17

Abstract: The molecular mechanisms by which hypoxic tumor cells escape radio- and chemotherapy are largely unclear. Homeodomain-interacting protein kinase 2 (HIPK2) drives the apoptotic program in response to DNA-damaging chemotherapeutic drug treatment by phosphorylating the tumor suppressor protein p53 at Ser46. HIPK2 is kept inactive in unstressed cells through ubiquitination and degradation facilitated by the ubiquitin ligases WSB1 and Siah1. Here, we demonstrate that HIPK2 is degraded during hypoxia in a proteasome-dependent and partially Siah1-dependent fashion. Concordantly, hypoxic tumor cells show an impaired p53 Ser46 phosphorylation in response to treatment with the chemotherapeutic Adriamycin. Remarkably, proteasome-inhibition rescues HIPK2 expression in hypoxic hepatoma cells and restores p53 Ser46 phosphorylation and caspase activity after Adriamycin treatment. Our findings suggest a molecular mechanism by which hypoxic cancer cells can escape chemotherapeutic drug treatment and suggest proteasome-inhibition as a promising approach to sensitise hypoxic cancer cells to therapy.

Mechanisms of breast cancer bone metastasis - Corrected Proof

Yunfei Zhang, Baoan Ma, Qingyu Fan — 2009-12-14

Abstract: Bone, as well as liver and lung, is one of the most preferential metastatic target sites for cancers including breast, prostate, and lung cancers and the consequences are always devastating. Like other metastasis, breast cancer bone metastasis consists of several steps from the escape of primary site to the colonization in target site. This review focuses on several key steps including: 1. Invasion and escape from primary tumor site. 2. Target migration toward bone. 3. Specific adhesion and arrest in bone. 4. Establishment of metastasis in bone. The factors involved in this process will provide good targets for therapy.

MicroRNA in pancreatic cancer: Pathological, diagnostic and therapeutic implications - Corrected Proof

Satyanarayana Rachagani, Sushil Kumar, Surinder K. Batra — 2009-12-10

Abstract: MicroRNAs (miRNAs) are a group of small non-coding RNA molecules of 17–25 nucleotides (nt) in length, predicted to control the activity of about 30% of all protein-coding genes in mammals. Altered expressions of miRNAs are reported in various cancers and may associate with cancer pathogenesis, apoptosis, and cell growth, thereby functioning as either tumor suppressors or oncogenes. Recent reports showed that deregulation of miRNA contribute to tumor development and progression and hence, have diagnostic and prognostic value in several human malignancies. This review discusses the current status of miRNA in pancreatic cancer development, progression, diagnosis, and therapy.

Arsenic trioxide-mediated Notch pathway inhibition depletes the cancer stem-like cell population in gliomas - Corrected Proof

Yunbo Zhen, Shiguang Zhao, Qiang Li, Yi Li, Keiji Kawamoto — 2009-12-07

Abstract: Cancer stem-like cells (CSLCs) are potential targets for treatment of glioblastoma multiforme (GBM) due to their role in tumorigenesis and recurrence. In this study, we investigated the inhibitory effect of arsenic trioxide (As2O3) on CSLCs of GBM in human glioma cell lines (U87MG, U251MG and U373MG) in vivo and in vitro. Immunofluorescence staining and flow cytometry revealed that the percentage of Nestin-positive cells in the aforementioned cell lines was diminished by 12%, 14% and 7%, respectively, after treatment with 2μM As2O3. Furthermore, we used soft-agar in U87MG and tumor xenografts in nude mice to demonstrate the ability of As2O3 to inhibit the formation of tumor in the three cell lines. These results indicate the negative regulation of CSLCs by As2O3. In addition, a Western blot analysis revealed decreased levels of Notch1 and Hes1 proteins due to As2O3 treatment. We conclude that As2O3 has a remarkable inhibitory effect on CSLCs in glioma cell lines in vivo and in vitro; in addition, we determined that the mechanism of CSLC inhibition involves the deregulation of Notch activation.

Cellular response and activation of apoptosis by mithramycin SK in p21WAF1-deficient HCT116 human colon carcinoma cells - Corrected Proof

Marc Bataller, Carmen Méndez, José A. Salas, José Portugal — 2009-12-07

Abstract: HCT116 (p21−/−) human colon carcinoma cells treated with mithramycin SK (MSK), a novel analog of the antitumor antibiotic mithramycin A (MTA), were transiently arrested in G2/M, with some cells entering a faulty mitotic cycle without cytokinesis that resulted in G1-like cell arrest, which consisted of post-mitotic aneuploid G1 cells. Some of these cells synthesized DNA and elicited an apoptotic response. The absence of p21WAF1 made HCT116 cells more sensitive to MSK than to the related MTA. MSK also showed higher antiproliferative activity than MTA on HCT116 cells with different genetic backgrounds, including those lacking the p53 gene. Apoptosis in MSK-treated p21−/− cells involved caspase 2 rather than caspase 3. Untreated HCT116 (p21−/−) cells presented a little caspase 3 activity, which increased slightly after treatment with MSK. The apoptotic response in p21−/− cells comprised caspase 2 acting as an executor caspase together with a loss of mitochondrial membrane potential that may be initiated by caspase 2. In contrast, caspase 3 was activated in wild-type HCT116 after treatment with MSK.

5-Bromotetrandrine enhances the sensitivity of doxorubicin-induced apoptosis in intrinsic resistant human hepatic cancer Bel7402 cells - Corrected Proof

Xiao Dong Liu, Hua Sun, Geng Tao Liu — 2009-12-04

Abstract: 5-Bromotetrandrine (BrTet) was shown to overcome multi-drug resistance (MDR) in vitro and in vivo by inhibiting the overexpression and efflux function of P-glycoprotein in our previous study. The purpose of the present study was to evaluate the effect of BrTet on the sensitivity of doxorubicin (Dox) induced apoptosis in intrinsic resistant human hepatic cancer Bel7402 cells. The cells were treated with non-toxic concentrations of BrTet (1μM, 2μM, 4μM) or the positive control drug verapamil (Vrp) (10μM) for 24h followed by a low dose Dox (3μM) for 24h. The results showed that BrTet pretreatment followed by Dox led to typical apoptotic characters as indicated by morphologic changes, DNA fragmentation and changes in cell cycle, while the same dose of BrTet, Vrp and Dox alone did not induce apoptosis in Bel7402 cells. In addition, the pretreatment of BrTet or Vrp followed by Dox induced activation of caspase-3, release of cytochrome c and AIF from mitochondria into cytosol, loss of mitochondrial transmembrane potential (ΔΨm) and elevation of Bax/Bcl-2 ratio, with no effect on activation of caspase-8 and the expression of Fas/FasL. In conclusion, BrTet pretreatment enhanced the sensitivity of Dox to induce apoptosis by causing loss of ΔΨm and elevating the ratio of Bax/Bcl-2, eventually activated mitochondrial apoptotic pathway. These findings further support the potential of BrTet to be used in clinical trail of cancer treatment.

Antitumor activity of novel fluoro-substituted (–)-epigallocatechin-3-gallate analogs - Corrected Proof

2009-12-04

Abstract: Epidemiological studies support the cancer-preventive effects of green tea and its main constituent (–)-epigallocatechin gallate [(–)-EGCG], however, (–)-EGCG is unstable under physiological conditions. Here we report that two novel fluoro-substituted (–)-EGCG analogs inhibited tumor growth with similar potency to that of Pro-EGCG (1) which has improved potency over parental compound (–)-EGCG in human breast cancer MDA-MB-231 xenografts. MDA-MB-231 tumors treated with each fluoro-substituted (–)-EGCG analog showed proteasome inhibition and apoptotic cell death, suggesting that the proteasome might be one of the cellular targets of fluoro-(–)-EGCGs and that proteasome inhibition is partially responsible for the observed antitumor activity.

Combined cetuximab and genistein treatment shows additive anti-cancer effect on oral squamous cell carcinoma - Corrected Proof

2009-12-03

Abstract: The purpose of this study was to evaluate the potency of EGFR pathway inhibition achieved by combining cetuximab, an anti-EGFR monoclonal antibody, and genistein, a tyrosine kinase inhibitor, which target extracellular and intracellular domains of the receptor, respectively, in oral squamous cell carcinoma (OSCC) in vitro and in vivo.Two OSCC cell lines, HSC3 and KB, were treated with cetuximab (C, 0–400μg/ml), genistein (G, 0–80μM), or a combination of both at a range of concentrations. Downstream protein expression of EGFR, p-EGFR, and p-Akt were evaluated by Western blot. Cell proliferation and apoptosis indices were calculated to assess anti-cancer effects in vitro. The in vivo effects of cetuximab and genistein on tumor cell growth were examined using an OSCC xenografted nude mouse model and immunohistochemical analyses of proliferation (PCNA) and microvessel density (CD31).Treatment of cells with dual anti-EGFR agents reduced the expressions of p-EGFR, and p-Akt in HSC3 cell line, but there was no significant difference in downregulation between cetuximab alone and in combination with genistein in KB cells. Both HSC3 and KB cells showed a dose-dependent decrease in cell proliferation significantly with single agent treatment and combination (p<0.05). In low concentration, combined cetuximab and genistein therapy resulted in additive growth inhibition and more apoptosis compared to that achieved with single-agent exposure in both cell lines. A combination of cetuximab and genistein significantly inhibited tumor growth and caused a substantial growth delay in in vivo models of both cell lines while each single-agent exposure caused no delay of tumor growth. Immunohistochemical staining with PCNA revealed that the group receiving combined cetuximab and genistein exhibited the lowest number of proliferating cells and microvessel density (p<0.05).Combined therapy with genistein and cetuximab can add the potency of EGFR signaling inhibition. Because not all OSCC cell types appear to respond uniformly, however, selective targeting of distinct molecular pathways is required for effective clinical response.

Histone acetyltransferase p300 is a coactivator for transcription factor REL and is C-terminally truncated in the human diffuse large B-cell lymphoma cell line RC-K8 - Corrected Proof

Michael R. Garbati, Gökçen Alço, Thomas D. Gilmore — 2009-11-30

Abstract: Human c-Rel (REL) is a member of the NF-κB family of transcription factors. REL’s normal physiological role is in the regulation of B-cell proliferation and survival. The REL gene is amplified in many human B-cell lymphomas and overexpression of REL can transform chicken lymphoid cells. In this report, histone acetyltransferase p300 enhanced REL-induced transactivation and interacted with REL both in vitro and in REL-transformed chicken spleen cells and the B-lymphoma cell line RC-K8, in which REL is constitutively active and required for proliferation. However, due to a deletion in the EP300 locus, only a C-terminally truncated form of p300 is expressed in RC-K8 cells. These results suggest a role for p300 in REL-mediated oncogenic activity in B lymphoma.

Therapeutic effect of genetically engineered mesenchymal stem cells in rat experimental leptomeningeal glioma model - Corrected Proof

Chunyu Gu, Shaoyi Li, Tsutomu Tokuyama, Naoki Yokota, Hiroki Namba — 2009-11-30

Abstract: Disseminating disease of high grade gliomas is difficult to treat. We examined the therapeutic effect of intrathecal administration of mesenchymal stem cells transduced with herpes simplex virus-thymidine kinase gene (MSCtk) followed by systemic ganciclovir (GCV) administration in rat experimental leptomeningeal glioma model. First, to examine in vivo bystander effect, rats were intrathecally co-injected with a mixture of MSCtk and C6 cells and then, intraperitoneally administered with GCV or saline for 10days (co-injection model). Next, to examine the therapeutic effect of MSCtk/GCV therapy, MSCtk cells were intrathecally administered 1day after C6 injection and then, GCV or saline was administered (treatment model). GCV administration significantly reduced tumor size on day 14 both in the co-injection model (0.41±0.22 vs. 3.10±0.97mm2, p<0.01) and in the treatment model (0.73±.29 vs. 2.84±0.82mm2, p<0.01). Survival was also significantly prolonged in GCV group both in the co-injection model (29.2±3.3 vs. 18.8±0.8days, p<0.001) and in the treatment model (21.5±1.5 vs. 17.2±0.5days, p<0.001). This study provided a novel treatment strategy for leptomeningeal glioma dissemination using intrathecal MSCtk injection followed by systemic GCV administration.

Cancer stem cells sustaining the growth of mouse melanoma are not rare - Corrected Proof

2009-11-30

Abstract: Cancer stem cell (CSC) is generally believed to be a very small proportion of tumor cells capable of initiating and sustaining growth of the tumor. Its existence is usually demonstrated by xenotransplanting human cancer cells in immunodeficient mice. In this paper, we report that the growth of B16-F10 melanoma cells in syngeneic mice could be maintained by a relatively larger proportion (>10%) of tumor cells. The result of this study does not seem to support the current view that cancer stem cells (CSCs) responsible for the sustainable growth of tumor are rare.

Increased endostatin generation and decreased angiogenesis via MMP-9 by tamoxifen in hormone dependent ovarian cancer - Corrected Proof

Christina Bendrik, Lisa Karlsson, Charlotta Dabrosin — 2009-11-30

Abstract: There are several similarities between breast and ovarian cancer but anti-estrogen treatment is rarely used in ovarian cancer. We have previously shown that the most widely used anti-estrogen tamoxifen increased MMP-9 activity and endostatin generation in breast cancer. Here, we show that tamoxifen exposure of highly hormone responsive ovarian cancer cells decreased proliferation, and increased MMP-9 activity leading to increased levels of endostatin both in cell culture in vitro and in solid tumors of nude mice. Tamoxifen exposed tumors also exhibited significantly decreased tumor growth and vascularisation. Moreover, in ascites from ovarian cancer patients, MMP-9 was undetectable in majority of cases but a significant correlation of MMP-2 and endostatin was found. The effects on MMPs and endostatin generation are previously unknown mechanisms of estradiol and tamoxifen in ovarian cancer, which may have therapeutic implications in future anti-cancer options of hormone dependent ovarian cancer.