miR-190 promotes malignant transformation and progression of human urothelial cells through CDKN1B/p27 inhibition.

Background: Although miR-190 has been reported to be related to human diseases, especially in the development and progression of cancer, its expression in human bladder cancer (BC) and potential contribution to BC remain unexplored.

Methods: RT-qPCR was used to verify the expression level of miR-190 and CDKN1B. Flow cytometry (FCM) assays were performed to detect cell cycle. Soft agar assay was used to measure anchorage-independent growth ability. Methylation-Specific PCR, Dual-luciferase reporter assay and Western blotting were used to elucidate the potential mechanisms involved.

Results: Our studies revealed that downregulation of the p27 (encoded by CDKN1B gene) protein is an important event related to miR-190, promoting the malignant transformation of bladder epithelial cells. miR-190 binds directly to CDKN1B 3'-UTR and destabilizes CDKN1B mRNA. Moreover, miR-190 downregulates TET1 by binding to the TET1 CDS region, which mediates hypermethylation of the CDKN1B promoter, thereby resulting in the downregulation of CDKN1B mRNA. These two aspects led to miR-190 inhibition of p27 protein expression in human BC cells. A more in-depth mechanistic study showed that c-Jun promotes the transcription of Talin2, the host gene of miR-190, thus upregulating the expression of miR-190 in human BC cells.

Conclusions: In this study, we found that miR-190 plays an important role in the development of BC. Taken together, these findings indicate that miR-190 may promote the malignant transformation of human urothelial cells by downregulating CDKN1B, which strengthens our understanding of miR-190 in regulating BC cell transformation.