Long non-coding RNA HOTAIR promotes tumourigenesis by affecting proliferation, invasion, migration, and apoptosis of liver cancer cells

Abstract

INTRODUCTION: Increasing evidence shows that Hox transcript antisense RNA (HOTAIR) plays a vital role in liver cancer initiation and progression by affecting the proliferation, invasion, migration, and apoptosis of liver cancer cells. However, the underlying mechanism of how HOTAIR exerts its functions in liver cancer cells remains unclear. Previous studies have shown that HOTAIR affects the invasion and migration of liver cancer cells by regulating the expression of E-cadherin. Snail2, a transcription factor involved in epithelial-mesenchymal transition, directly binds to the E-boxes of the E-cadherin promoter to repress its transcription. The aim of the study was to examine the correlation between HOTAIR and Snail2 in the HOTAIR/Snail2/E-cadherin signal pathway and explore the role of HOTAIR in the proliferation, invasion, migration, and apoptosis of liver cancer cells.
MATERIALS AND METHODS: Fifty matched normal liver tissues and 373 liver cancer tissues were analysed and evaluated. HepG2 and SNU-387 cells were cultured and transfected with plasmids knocking down HOTAIR to disrupt HOTAIR expression. Cell scratch and transwell assays were performed to examine the migration and invasion of HepG2 and SNU-387 cells; in addition, the expression of MMP2 and MMP9 was detected by immunoblotting analysis, RT-qPCR analysis, immunofluorescence analysis, and bioinformatics analysis, which elucidated the regulatory relationship between HOTAIR and Snail2. We used flow cytometry and JC-1 probe analysis assays to clarify the function of HOTAIR inliver cancer cell apoptosis.
RESULTS: The HOTAIR mRNA was upregulated in liver cancer tissues, which was related to worse overall survival. HOTAIR induced the expression of matrix metalloproteinase-9 (MMP9) and metalloproteinase-2 (MMP2), leading to degradation of extracellular matrix. HOTAIR knockdown significantly reduced the doubling time and inhibited cell migration and invasion of liver cancer cells. Furthermore, HOTAIR depletion induced mitochondrial-related apoptosis in HepG2 and SNU-387 cell lines.
CONCLUSIONS: In this study, we propose a novel mechanism in which HOTAIR promotes invasion and migration of liver cancer cells by regulating the nuclear localisation of Snail2.