The regulation and interaction of PVT1 and miR181a-5p contributes to the repression of SP1 expression by the combination of XJD decoction and cisplatin in human lung cancer cells.

The Chinese herbal prescription Xiaoji decoction (XJD) has been used as an adjuvant treatment of cancer for decades. However, the molecular mechanisms underlying XJD enhancement of the efficiency of chemotherapy were undetermined. In this study, we observed that combination of XJD and cisplatin (DDP) showed a greater inhibition on growth and induced a high magnitude of apoptosis in non-small cell lung cancer (NSCLC) cells. We also found that XJD decreased lncRNA PVT1 and increased miR181a-5p expressions. There was a reciprocal interaction between PVT1 and miR181a-5p. XJD decreased SP1 protein, which were overcame by overexpressed PVT1 and inhibitors of miR181a-5p. Overexpressed SP1 reversed the inhibitory effect of XJD on cell growth. Importantly, XJD and DDP exhibited synergy on regulation of PVT1, miR181a-5p, and SP1 expressions. The similar results were observed in one in vivo model. In conclusions, XJD inhibits NSCLC cell growth via reciprocal interaction of PVT1 and miR181a-5p followed by reducing SP1 expression. XJD and DDP exhibit synergy. This study provides a novel mechanism by which XJD enhances the anti-cancer effect of DDP in NSCLC cells.