miR­22­3p enhances multi­chemoresistance by targeting NET1 in bladder cancer cells.

With the discovery of new chemotherapeutic drugs, chemotherapy becomes increasingly valuable. However, the resistance of tumor cells to chemotherapeutic agents significantly limits the effectiveness and causes chemotherapy failure. MicroRNAs have been shown to regulate drug resistance in many types of cancer. In the present study, we measured the chemosensitivity of five bladder cancer (BCa) cell lines to seven commonly used chemotherapeutic drugs by Vita­Blue assay. We then identified the most sensitive (5637) and most tolerant cell lines (H­bc) and conducted a multi­group test. This test included expression group analyses of coding and non­coding genes (miR­omic and RNA­seq). Based on our analyses, we selected miR­22­3p as a target. We then determined its own target gene [neuroepithelial cell transforming 1 (NET1)] by bioinformatic analysis and confirmed this finding by TaqMan­quantitative reverse transcription polymerase chain reaction (qRT­PCR), western blot analysis and luciferase reporter assay. The effect of miR­22­3p on BCa multi­chemoresistance was also determined by transfecting cells with the miR­22­3p­mimic or miR­22­3p­antagomiR. We assessed the involvement of NET1 in BCa chemoresistance by siRNA­mediated NET1 inhibition or pINDUCER21­enhanced green fluorescent protein­NET1­mediated overexpression. Plate colony formation and apoptosis assays were conducted to observe the effects of miR­22­3p and NET1 on BCa chemoresistance. In conclusion, our results suggest that miR­22­3p promotes BCa chemoresistance by targeting NET1 and may serve as a new prognostic biomarker for BCa patients.