MEX3A promotes cell proliferation by regulating the RORA/β-catenin pathway in hepatocellular carcinoma.

Abstract

Background: MEX3A is a member of the human homologous gene MEX-3 family. It has been shown to promote cell proliferation and migration in various cancers, indicating its potential clinical significance. However, the role of MEX3A in hepatocellular carcinoma (HCC) remains largely unexplored, with limited reports available in the literature.

Aim: To investigate expression and clinical significance of MEX3A in HCC and explore its potential role in tumor progression.

Methods: We analyzed MEX3A mRNA expression in HCC and adjacent tissues using data from The Cancer Genome Atlas (TCGA). The correlation between MEX3A expression and overall survival (OS) was evaluated. Immunohistochemistry was performed on HCC surgical specimens to validate MEX3A expression and its association with clinical parameters, including hepatitis B virus (HBV) positivity, tumor differentiation and tumor size. Additionally, MEX3A knockdown HCC cell lines were constructed to explore the biological functions of MEX3A. Cell proliferation was assessed using cell counting kit-8 and clone formation assays, while cell cycle progression was analyzed by flow cytometry. The effects of MEX3A on the Wnt/β-catenin signaling pathway were examined by western blotting and immunofluorescence. Cell migration was evaluated using scratch and Transwell assays. Finally, the role of the transcription factor RORA in mediating MEX3A effects was explored by silencing RORA and analyzing its impact on cell proliferation and protein expression.

Results: TCGA data analysis revealed that MEX3A mRNA expression was significantly higher in HCC tissues compared to adjacent tissues. Higher MEX3A expression was associated with poorer OS. These findings were validated in HCC surgical specimens. Immunohistochemistry confirmed elevated MEX3A expression in HCC tissues and showed positive correlations with Ki-67 and vimentin levels. MEX3A expression was closely related to HBV positivity, tumor differentiation and tumor size. Mechanistic studies demonstrated that MEX3A knockdown inhibited cell proliferation and cell cycle progression, as shown by reduced expression of β-catenin, c-Myc and cyclin D1. Additionally, MEX3A knockdown inhibited the nuclear entry of β-catenin, thereby suppressing the activation of downstream oncogenic pathways. MEX3A depletion significantly reduced the migratory ability of HCC cells, likely through downregulation of the epithelial-mesenchymal transition pathway. Transcription factor analysis identified RORA as a potential mediator of MEX3A effects. Silencing RORA antagonized the effects of MEX3A on cell proliferation and the expression of β-catenin, c-Myc and cyclin D1.

Conclusion: MEX3A promotes cell proliferation in HCC by regulating the RORA/β-catenin pathway. Our findings suggest that MEX3A could serve as a prognostic marker and therapeutic target for HCC.