MDC1 functionally identified as an androgen receptor co-activator participates in suppression of prostate cancer.
Bottom Line: Moreover, depletion of MDC1 results in decreased expression of a subset of the endogenous androgen-induced target genes, including cell cycle negative regulator p21 and PCa metastasis inhibitor Vinculin, in AR positive PCa cell lines.Finally, the expression of MDC1 and p21 correlates negatively with aggressive phenotype of clinical PCa.These studies suggest that MDC1 as an epigenetic modifier regulates AR transcriptional activity and MDC1 may function as a tumor suppressor of PCa, and provide new insight into co-factor-AR-signaling pathway mechanism and a better understanding of the function of MDC1 on PCa.
Affiliation: Department of Cell Biology, Key laboratory of Cell Biology, Ministry of Public Health, and Key laboratory of Medical Cell Biology, Ministry of Education, China Medical University, Shenyang, Liaoning 110122, China.Show MeSH
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Mentions: To investigate whether MDC1 is able to enhance AR-induced transactivation in human cells, a series of luciferase assays were performed in human cells. Our results demonstrated that in LNCaP cells, MDC1 full length (FL), MDC1 N3 and C1, but not MDC1 N1 and N2, significantly enhanced AR-mediated transactivation in the presence of DHT (Figure 3A), suggesting that MDC1 co-activates AR-mediated transactivation in a ligand-dependent manner and its functional co-activation domains are located in N-terminal 500–1000 aa fragment or 1699–2089 aa at the C-terminus. In CWR22Rv1 cells which constitutively carry AR FL and ligand-independent AR variants, knockdown of MDC1 repressed AR-mediated transactivation with or without DHT treatment, suggesting MDC1 may participate in upregulation of AR FL or AR variants-induced transactivation (Figure 3B). To confirm these results, we further separately detected effects of MDC1 on the truncated AR harboring the ligand-independent AF-1 domain (ARAF-1) or ligand-dependent AF-2 domain (ARAF-2). The results demonstrated that ARAF-1-mediated transactivation was constitutively enhanced by MDC1 in an androgen-independent manner (Figure 3C). And the transactivation function of ARAF-2 was enhanced by MDC1 in the presence of DHT (Figure 3D). Moreover, the transactivational activity of AR-V7, which is well-studied N-terminal variant of AR, was enhanced by MDC1 without DHT (Supplementary Figure S4). These data indicated that MDC1 is involved in regulation of AR FL and AR variant functions. In addition, as shown in Figure 3E, MDC1 enhances not only AR, but also ERα and GR-induced transactivation in a ligand-dependent manner, suggesting that MDC1 may be involved in up-regulation of a series of NRs-mediated functions.
Affiliation: Department of Cell Biology, Key laboratory of Cell Biology, Ministry of Public Health, and Key laboratory of Medical Cell Biology, Ministry of Education, China Medical University, Shenyang, Liaoning 110122, China.