406986

MIR203A

microRNA 203a;MIR203A;microRNA 203a

hsa-mir-203|microRNA 203

14q32.33

ncRNA

MicroRNAs (miRNAs) are small, non-coding RNAs that are critical regulators of various diseases. MicroRNA- 20a (miR-20a) and microRNA-203 (miR-203) have previously shown significant alteration in a range of cancers. In this study, the expression levels of miR-20a and miR-203 in 100 cervical cancer tissues were detected by qRT-PCR and compared to patient matched-nontumor cervical tissues. Correlations between expression level and clinicopathologic characteristics of cervical cancer were also analyzed. Finally, we studied the effect of miR- 20a and miR-203 on cell proliferation in cervical cancer cell lines by MTT. We found that the expression level of miR-20a (P<0.001) was significantly higher in cervical cancer patients than in healthy controls, while that of miR-203 (P<0.001) was lower. Aberrant expression of miR-20a was correlated with lymph node metastasis (LNM), histological grade and tumor diameter, but down-regulated miR-203 was correlated with LNM only. Furthermore, we found that over-expression of miR-203 decreased cell proliferation, while reduction of miR- 20a also prevented tumor progression. Our results support the involvement of miR-20a and miR-203 in cervical tumorigenesis. We propose that miRNAs might be used as therapeutic agents for cervical cancer.

TGF-beta promotes tumor invasion and metastasis by inducing an epithelial-mesenchymal transition (EMT). Understanding the molecular and epigenetic mechanisms by which TGF-beta induces EMT may facilitate the development of new therapeutic strategies for metastasis. Here, we report that TGF-beta induced SNAI2 to promote EMT by repressing miR-203. Although miR-203 targeted SNAI2, SNAI2 induced by TGF-beta could directly bind to the miR-203 promoter to inhibit its transcription. SNAI2 and miR-203 formed a double negative feedback loop to inhibit each other's expression, thereby controlling EMT. Moreover, we found that miR-203 was significantly down-regulated in highly metastatic breast cancer cells. The restoration of miR-203 in highly metastatic breast cancer cells inhibited tumor cell invasion in vitro and lung metastatic colonization in vivo by repressing SNAI2. Taken together, our results suggest that the SNAI2 and miR-203 regulatory loop plays important roles in EMT and tumor metastasis.

The epithelial-mesenchymal transition (EMT) imparts metastatic competence on otherwise non-metastatic cancer cells through decreased inter-cellular adhesions, increased migratory capacity, stem cell properties and anoikis and chemotherapy resistance. In this study, we profiled changes in microRNA expression during EMT in conjunction with changes in DNA methylation at microRNA promoters to discover essential mediators of EMT-imparted stemness properties. MicroRNA-203 (miR-203) expression is repressed following EMT induced by multiple different stimuli and in established claudin-low cell lines as well as the CD44hi/CD24lo stem cell-enriched fraction. expression of miR-203 in mesenchymal cells compromises migratory and invasive capacity in vitro, and tumor initiation and metastasis in vivo. Unexpectedly, miR-203 expression affects the sphere-forming capacity of neighboring cells by indirectly enhancing expression of DKK1, a secreted inhibitor of Wnt signaling and stemness resulting in suppression of beta-catenin protein levels. Our data suggest that restoring miR-203 expression levels may inhibit metastasis and combat deregulated Wnt signaling.