LncRNA XIST acts as a ceRNA sponging miR-185-5p to modulate pancreatic cancer cell proliferation via targeting CCND2

BACKGROUND: Long non-coding RNAs (lncRNAs) have been proved to be involved in the occurrence and progression of various tumors including pancreatic cancer (PC). Growing evidence shows that lncRNA X inactive-specific transcript (XIST) functions as an oncogene in multiple tumorigenesis. However, the underlying mechanism of lncRNA XIST in the progression of PC remains elusive. METHODS: Expression levels of XIST and miR-185-5p both in PC tissues or PC cells were determined using real-time quantitative PCR (qRT-PCR). Gain and loss-of-function of XIST or miR-185-5p was performed for further exploration. Moreover, colony formation assay was performed to assess cell proliferation. Flow cytometry analysis was performed to measure cell cycle and apoptosis. Dual-luciferase reporter assay was conducted to verify the correlation between XIST, miR-185-5p and CCND2, respectively. Additionally, western blot analysis was conducted to determine the expression pattern of apoptosis-related proteins and cell cycle-associated proteins. RESULTS: Herein, we found that XIST expression was up-regulated while miR-185-5p was down-regulated both in PC tissues and cell lines, compared with that of controls. Moreover, there was a negative correlation between XIST and miR-185-5p. Following that, functional experiments displayed that knockdown of XIST or overexpression of miR-185-5p inhibited cell proliferation, induced cell cycle arrest and promoted apoptosis in PC cells. Furthermore, mechanistic experiments displayed that XIST could negatively regulate miR-185-5p via direct binding. In addition, CCND2 was shown to be a downstream target of miR-185-5p. Importantly, overexpression or knockdown of XIST significantly increased or decreased the expression of CCND2, while these effects were reversed by miR-185-5p. CONCLUSIONS: Taken together, our study demonstrated that lncRNA XIST functions as an oncogene and exerts its regulation via miR-185-5p/CCND2 axis, promoting proliferation and inhibiting apoptosis in PC.