Original ArticlesMED27 promotes melanoma growth by targeting AKT/MAPK and NF-κB/iNOS signaling pathways
Introduction
Melanoma is an aggressive type of cutaneous malignancy. It is more serious than other skin cancers because of its aggressiveness and poses a great threat to the health of people in the world, especially in the Western world. Although most melanomas can be cured with surgery, the prerequisite is early detection. In case of metastasis, it usually causes serious illnesses and even death [1], [2], [3], [4]. About 76,000 new cases of melanoma are diagnosed in the United States every year and more than 9000 deaths happened in 2014 [5]. Furthermore, the risk of melanoma seems to be increased towards a younger trend in people under 40 and the averaged survival rate for patients with metastasis is currently only 6–12 months. Although the inhibitors targeting BRAF and/or MEK pathways provide a therapeutic option for non-resectable melanoma driven by BRAF mutation [6], [7], [8], a fair proportion of melanomas are BRAF wild type, or NRAS-mutant, or TERT-mutant and are insensible to the above mutation-targeting therapy [9], [10], [11], [12]. Collectively, based on the high morbidity, high mortality and high complexity of molecular mechanisms associated with metastatic melanoma, more attention should be paid to clarify the underlying molecular mechanisms involved in the disease progression and identify newly potential therapeutic targets to improve the treatment.
The human mediator complex (MED), composed of 28 elements, represents a fundamental component of the transcription machinery and interacts with the RNA polymerase II enzyme to regulate its ability to control gene expression [13]. As a component of these 28 elements, MED27 is an enzyme ubiquitously expressed in humans and universally required in transcriptional initiation [14]. It is reported as a subunit of CRSP complex (cofactor required for SP1 activation), which is recruited by Sp1 through direct interactions to promoters and serves as a scaffold for the assembly of other regulatory proteins to promote the transcription of SP1-driven down-stream target genes [15]. MED27 is also found to interact with thyroid hormone receptor (TR) to facilitate TR function by conjunction with other transcriptional factors and co-factors [16]. In addition, the new findings demonstrated its involvement in HIV-1 transcription. Knockdown of MED27 protein, combined with the knockdown of other MED proteins, significantly impaired viral replication without affecting cell viability [17]. However, to date, unlike other members of MED family, the functional role of MED27 in human diseases is still rarely reported, and its function in respect to tumorigenesis and development is especially poorly characterized, or even nearly unknown.
Our research based on siRNA library screening has identified a serial of new proteins implicated in melanoma progression [18]. Here, we chose one of these proteins, MED27, as the main study object and provided an evaluation of its activity on melanoma cell growth and apoptosis. Moreover, we explored its potential molecular mechanisms associated with melanoma survival and its clinical significance in melanoma. Our results have shown that knockdown of MED27 leads to reduced cell proliferation, increased cell cycle repression and apoptosis in melanoma, and such proliferation-inhibiting effects of MED27 knockdown is mediated by inactivating PI3K/AKT, MEK/Erk pathway, elevating Bcl-2/Cyt C/Caspase 3 signaling pathway and inhibiting NF-κB/iNOS signaling pathway. Our researches not only demonstrated the role of MED27 in melanoma progress at first time, but also provided a potential candidate therapeutic target for melanoma treatment.
Section snippets
Cell lines and cell culture
Human melanoma cell lines MeWo, SK-Mel-28, A375, C8161 and immortalized human epidermal cell line HaCaT,normal skin cell SK were all obtained from the American Type Culture Collection (ATCC). These cells were all cultured in Dulbecco,s Modified Eagle Medium supplemented with 10% FBS, 100 µg/mL penicillin, and 100 µg/mL streptomycin. The cultures were maintained in an incubator with 5% CO2 at 37 °C under standard culture condition.
Transient transfection
To overexpress MED27 in A375 or SK-Mel-28 cells, cells were
MED27 was highly expressed in melanoma cells and tumor tissues
To analyze the expression level of MED27 in human melanoma, we first detected the protein level of MED27 in human normal skin cell line SK, Knot (K) and fibroblasts (F), immortalized human epidermal cell line (HaCaT) and melanoma cell lines (MeWo, A375, SK-Mel-28, C8161) by Western blotting. MED27 was expressed in all the tested cell lines and a comparatively low expression was shown in normal skin cells (SK, Knot and fibroblasts) compared to the melanoma cells (Fig. 1A). We next tested the
Discussion
Given the demonstration of the mutations or overexpression of some mediator complex subunits (MED) in various human cancer [26], [27], [28], [29], [30], MED proteins have been recognized to play an increasingly important role in tumorigenesis and development. However, MED subunits most recently reported to be involved in tumor growth have been limited to MED1, 12, 14, 15, 19 ,24, and 28 [31], [32], [33], [34], [35], and little is known about the functional role of other subunits of Med complex
Conflict of interest
We declare there are not any competing financial interests in relation to the work described.
Acknowledgements
This work was supported by the funds from the National Natural Science Foundation of China (81301721, 81472178, 81071687, 81272195), the State “863 Program” of China (SS2012AA020403), the State “973 Program” of China (2014CB542005), the Education Department of Liaoning Province, China (the “Program for Pan-Deng Scholars”), the Natural Science Foundation of Liaoning Province (2014023009).
References (41)
- et al.
MED1/TRAP220 exists predominantly in a TRAP/ Mediator subpopulation enriched in RNA polymerase II and is required for ER-mediated transcription
Mol. Cell
(2005) - et al.
Characterization of the influence of mediator complex in HIV-1 transcription
J. Biol. Chem
(2014) - et al.
miRNA-221 and miRNA-222 induce apoptosis via the KIT/AKT signalling pathway in gastrointestinal stromal tumours
Mol. Oncol
(2015) - et al.
Late recurrence of malignant melanoma. Analysis of 168 patients
Ann. Surg
(1990) - et al.
Meta-analysis of phase II cooperative group trials in metastatic stage IV melanoma to determine progression-free and overall survival benchmarks for future phase II trials
J. Clin. Oncol
(2008) Role of surgery for metastatic malignant melanoma: a review
Semin. Surg. Oncol
(1993)- et al.
Survival rates of patients with metastatic malignant melanoma
J. Med. Life
(2014) - et al.
Biomarker use is associated with reduced clinical trial failure riSK in metastatic melanoma
Biomark Med
(2015) - et al.
Combining BRAF inhibition with modulators of the mitochondrial bioenergy metabolism to overcome drug resistance in metastatic melanoma
Exp. Dermatol
(2015) - et al.
Dabrafenib and trametinib, alone and in combination for BRAF-mutant metastatic melanoma
Clin. Cancer Res
(2014)
Improved overall survival in melanoma with combined dabrafenib and trametinib
N. Engl. J. Med
Multiple BRAF Wild-Type melanomas during dabrafenib treatment for metastatic BRAF-Mutant melanoma
JAMA Dermatol
where next for melanoma therapy?
Br. J. Cancer
TERT promoter mutation status as an independent prognostic factor in cutaneous melanoma
J. Natl Cancer Inst
BRAF/NRAS wild-type melanoma, NF1 status and sensitivity to trametinib
Pigment Cell Melanoma Res
The Mediator complex: a master coordinator of transcription and cell lineage development
Development
Comparative genomics supports a deep evolutionary origin for the large, four-module transcriptional mediator complex
Nucleic Acids Res
The transcriptional cofactor complex CRSP is required for activity of the enhancer-binding protein Sp1
Nature
Identification of unique sensitizing targets for anti-inflammatory CDDO-Me in metastatic melanoma by a large-scale synthetic lethal RNAi screening
Pigment Cell Melanoma Res
Inducible nitric oxide synthase and nitrotyrosine in human metastatic melanoma tumors correlate with poor survival
Clin. Cancer Res
Cited by (30)
Knockdown of mediator complex subunit 27 suppresses gastric cancer cell metastasis and angiogenesis via Wnt/β-catenin pathway
2022, Tissue and CellCitation Excerpt :MED27 was highly expressed in breast cancer tissues, and stimulated malignant behavior of cancer cells (Wang et al., 2020). Moreover, loss of MED27 inhibited cell proliferation, and promoted cell apoptosis and cell cycle arrest of melanoma cells (Tang et al., 2016). Down-regulation of MED27 was involved in miR-18a-mediated suppression of osteosarcoma (Ding et al., 2018).
circRNA circMED27 acts as a prognostic factor and mediator to promote lenvatinib resistance of hepatocellular carcinoma
2022, Molecular Therapy Nucleic AcidsCitation Excerpt :Therefore, we concluded that circMED27 can act as a molecular biomarker for lenvatinib-sensitivity predication and as a potential treatment target for HCC patients. Previous studies have reported that MED27 expression was significantly increased in several cancers.10,11 However, the expression pattern of MED27 in HCC tissues has not been reported.
A differential evolution based feature combination selection algorithm for high-dimensional data
2021, Information SciencesCitation Excerpt :SNP rs1363688 resides in the non-coding region. rs2224762 is located in the KDM4C gene, which regulates gene expression and chromosome segregation [37], and rs9328536 resides in the MED27 gene, which has been reported to be associated with melanoma [29,27]. ( rs380390, rs1374431) and (rs380390, rs2402053) were identified by HGDE, CINOEDV(P), epiACO, and FHSA-SED.
Acquired Uniparental Disomy Regions Are Associated with Disease Outcome in Patients with Oral Cavity and Oropharynx But Not Larynx Cancers
2020, Translational OncologyCitation Excerpt :Overexpression of MED27 plays role in cell proliferation, invasion, and metastasis through Wnt/b-catenin pathway in vivo and in vitro in adrenal cortical carcinogenesis, and silencing MED27 inhibits adrenal cortical carcinogenesis and epithelial-mesenchymal transition [30]. Its expression contributes to cell growth by activating AKT/MAPK and NF-kB/iNOS pathways in melanoma [31]. Moreover, miR-18a inhibits cell growth and induces apoptosis by downregulating the MED27 and Akt phosphorylation in osteosarcoma [32].
LASP1 promotes glioma cell proliferation and migration and is negatively regulated by miR-377-3p
2018, Biomedicine and Pharmacotherapy
- 1
These authors contributed equally to this manuscript.