Overexpression of the long non-coding RNA SPRY4-IT1 promotes tumor cell proliferation and invasion by activating EZH2 in hepatocellular carcinoma.

BACKGROUND: Increasing evidences have demonstrated that the dysregulation of long non-coding RNAs (lncRNAs) may act as an important role in tumor progression. The long non-coding RNA SPRY4 intronic transcript 1 (SPRY4-IT1) has been reported in some cancer including regulating cell growth, differentiation, apoptosis, and cancer progression. However, the expression and function of SPRY4-IT1 in the progression of hepatocellular carcinoma (HCC) remain largely unknown.

METHODS: The lncRNA SPRY4-IT1 was detected by quantitative real time PCR (qRT-PCR) in HCC cell lines, CCK8 cell proliferation and transwell invasion assays were performed to detect the GC cell proliferation and invasion abilities. The protein expression of E-cadherin, Vimentin and Twist1 was analyzed by Western blotting assays. Furthermore, RNA immunoprecipitation (RIP) and Chromatin immunoprecipitation (ChIP) assays were used to analyze potential molecular mechanism of SPRY4-IT1 in HCC cells.

RESULTS: We found that SPRY4-IT1 was up-regulated in HCC cell lines. Further function analysis demonstrated that knockdown of SPRY4-IT1 significantly inhibited HCC cells proliferation and invasion, but over-expression of SPRY4-IT1 had the opposite effects on HCC cells in vitro. Moreover, our results also indicated that SPRY4-IT1 over-expression significantly promoted the epithelial-mesenchymal transition (EMT) by up-regulating the transcription factor Twist1 and EMT marker Vimentin and inhibited the E-cadherin expression in MHCC97L cell. Whereas, knockdown of SPRY4-IT1 suppressed the transcription factor Twist1 and EMT marker Vimentin and increased the E-cadherin expression in MHCC97H cells. Mechanisms investigations showed that SPRY4-IT1 interacted with the EZH2 and epigenetically repressed the E-cadherin expression. In vivo, we also demonstrated that the tumor growth was inhibited in SPRY4-IT1 knockdown group compared with the control group.

CONCLUSIONS: These results suggested that lncRNA SPRY4-IT1 might be considered as a therapeutic target in HCC.