406988

MIR205

microRNA 205;MIR205;microRNA 205

hsa-mir-205

1q32.2

ncRNA

Recent studies have demonstrated that miR-205 has a role in both normal development and cancer, however conflicting reports on its function illustrate the complexity of its regulation and targets. Additionally, miR-205 was found to be highly expressed in stem cell-enriched populations from the mouse mammary gland, and thus may play a function in normal mammary stem cell maintenance. The role that miR-205 plays in tumor formation and metastasis is likely context-dependent as reports have indicated that it may function as either a tumor suppressor or an oncogene. The role that miR-205 plays in directing stem cell fate is still unknown.

In this study, we used formalin-fixed paraffin-embedded melanocytic tumors to demonstrate reproducible alterations in microRNA expression in nevi compared with melanomas using a microarray platform. We validated those results in an independent set of nevi and melanomas by quantitative RT-PCR. miR-205 demonstrated a statistically significant, progressive diminution in expression from nevi to primary melanomas to metastatic melanomas. Enforced miR-205 expression in melanoma cells profoundly impairs cell motility and migration along with significantly decreased F-actin polymerization with only a modest reduction in cell proliferation. Using a xenograft model, melanoma cells overexpressing miR-205 exhibit a reduced migratory capacity compared with control tumor cells. Mechanistically, miR-205 overexpression results in decreased expression of the zinc-finger E-box binding homeobox 2 (ZEB2) mRNA and protein. This coincides with increased expression of E-cadherin mRNA and protein. Furthermore, re-introduction of ZEB2 into melanoma cells overexpressing miR-205 rescues these phenotypic effects and results in a restoration of cell migration and F-actin polymerization with a concomitant reduction in E-cadherin expression. Together, these results provide in vitro and in vivo evidence for miR-205 as a critical suppressor of melanoma cell migration.

BACKGROUND: TMPRSS4 is a membrane-anchored protease involved in cell migration and invasion in different cancer types including lung cancer. TMPRSS4 expression is increased in NSCLC and its inhibition through shRNA reduces lung metastasis. However, molecular mechanisms leading to the protumorigenic regulation of TMPRSS4 in lung cancer are unknown. METHODS: miR-205 was identified as an overexpressed gene upon TMPRSS4 downregulation through microarray analysis. Cell migration and invasion assays and in vivo lung primary tumour and metastasis models were used for functional analysis of miR-205 overexpression in H2170 and H441 cell lines. Luciferase assays were used to identify a new miR-205 direct target in NSCLC. RESULTS: miR-205 overexpression promoted an epithelial phenotype with increased E-cadherin and reduced fibronectin. Furthermore, miR-205 expression caused a G0/G1 cell cycle arrest and inhibition of cell growth, migration, attachment to fibronectin, primary tumour growth and metastasis formation in vivo. Integrin alpha5 (a proinvasive protein) was identified as a new miR-205 direct target in NSCLC. Integrin alpha5 downregulation in lung cancer cells resulted in complete abrogation of cell migration, a decreased capacity to adhere to fibronectin and reduced in vivo tumour growth, compared with control cells. TMPRSS4 silencing resulted in a concomitant reduction of integrin alpha5 levels. CONCLUSION: We have demonstrated for the first time a new molecular pathway that connects TMPRSS4 and integrin alpha5 through miR-205 to regulate cancer cell invasion and metastasis. Our results will help designing new therapeutic strategies to inhibit this novel pathway in NSCLC.

p63 inhibits metastasis. Here, we show that p63 (both TAp63 and DeltaNp63 isoforms) regulates expression of miR-205 in prostate cancer (PCa) cells, and miR-205 is essential for the inhibitory effects of p63 on markers of epithelial-mesenchymal transition (EMT), such as ZEB1 and vimentin. Correspondingly, the inhibitory effect of p63 on EMT markers and cell migration is reverted by anti-miR-205. p53 mutants inhibit expression of both p63 and miR-205, and the cell migration, in a cell line expressing endogenous mutated p53, can be abrogated by pre-miR-205 or silencing of mutated p53. In accordance with this in vitro data, DeltaNp63 or miR-205 significantly inhibits the incidence of lung metastasis in vivo in a mouse tail vein model. Similarly, one or both components of the p63/miR-205 axis were absent in metastases or colonized lymph nodes in a set of 218 human prostate cancer samples. This was confirmed in an independent clinical data set of 281 patients. Loss of this axis was associated with higher Gleason scores, an increased likelihood of metastatic and infiltration events, and worse prognosis. These data suggest that p63/miR-205 may be a useful clinical predictor of metastatic behavior in prostate cancer.