Long non-coding RNA placenta‑specific protein 2 regulates the chemosensitivity of cancer cells to cisplatin in hepatocellular carcinoma (HCC) by sponging microRNA-96 to upregulate X-linked inhibitor of apoptosis protein

This study was conducted to investigate the roles of lncRNA PLAC2 and XiaP in hepatocellular carcinoma (HCC). HCC and paired non-tumor tissues were collected from 62 HCC patients who received cisplatin-based treatment. At 0, 2, and 4 months of post-cisplatin-based therapy, blood samples (5 ml) were collected from all patients and prepared plasma samples. LncRNA PLAC2 expression in tissue and plasma samples was determined by RT-qPCR. The interactions between lncRNA PLAC2 and XiaP in HCC cell lines were assessed by overexpression experiments. Cell viability and apoptosis under cisplatin treatment were analyzed by MTT assay and cell apoptosis assay, respectively. The direct interaction between lncRNA PLAC2 and miR-96, which can target XiaP, was analyzed by performing RNA-RNA pulldown assay. It was observed that lncRNA PLAC2 was upregulated in HCC tissues than in non-tumor tissues. LncRNA PLAC2 expression in HCC tissues was not affected by HBV and HCV but upregulated after cisplatin-based treatment. Similarly, cisplatin treatment of HCC cells increased PLAC2 expression. LncRNA PLAC2 and XiaP overexpression increased viability and decreased apoptosis of cisplatin-treated HCC cells, while lncRNA PLAC2 knockdown decreased viability and increased apoptosis of cisplatin-treated HCC cells. Western blot analysis showed that lncRNA PLAC2 increased XiaP protein accumulation, while lncRNA PLAC2 siRNA silencing decreased XiaP expression in HCC cells. LncRNA PLAC2 and miR-96 directly interacted with each other, while they failed to regulate the expression of each other. In conclusion, lncRNA PLAC2 negatively regulates the chemosensitivity of HCC cells to cisplatin, possibly by sponging miR-96 to upregulate miR-96.