Background: Chemoresistance contributes to treatment failure of gastric cancer (GC) patients but the molecular mechanism of chemoresistance in GC is still unclear. Long-chain noncoding RNA (lncRNA) urothelial cancer associated 1 (UCA1 ) is associated with resistance to chemotherapy drugs.
Methods: We detected the expression of UCA1  in 53 pairs of GC tumor tissue and adjacent normal tissue, human normal gastric mucosa cells (GES-1) and human GC cells (HGC-27, SNU-5, AGS, SGC-7901, and NCI-N87) using RT-qPCR. Small RNA interference technology was used to knock down the expression of UCA1  in gastric cancer cells. CCK8 solution was used to detect cell viability. Flow cytometry was used to detect apoptosis, and Western blotting was used to detect protein expression.
Results: UCA1  was highly expressed in GC tissues and cells, and knockdown of UCA1  increased chemosensitivity to cisplatin by inducing cell apoptosis. Furthermore, UCA1  promoted CYP1B1  expression by binding to miR-513a-3p  in human GC cells in vitro, and UCA1 /CYP1B1  expression was negatively related to miR-513a-3p  expression, while UCA1  expression was positively related to CYP1B1  expression in human GC tissues. Moreover, overexpression of miR-513a-3p  or knockdown of CYP1B1  increased chemosensitivity to cisplatin, and knockdown of miR-513a-3p  or overexpression of CYP1B1  decreased chemosensitivity to cisplatin by inducing cell apoptosis in human GC cells. Importantly, overexpression of CYP1B1  reduced chemosensitivity to cisplatin which increased by knockdown of UCA1 , and knockdown of CYP1B1  increased chemosensitivity to cisplatin which decreased by knockdown of miR-513a-3p  in human GC cells.
Conclusion: The lncRNA UCA1 /miR-513a-3p /CYP1B1  axis regulates cisplatin resistance in human GC cells; hence, it is a potential target for treating chemoresistance in GC.
Keywords: gastric cancer, urothelial cancer associated 1, chemoresistance