TGF-β induces a decrease in CAPZA1 expression to promote the invasiveness of hepatocellular carcinoma cells

Abstract

Background

CAPZA1 is underexpressed in hepatocellular carcinoma (HCC), and its downregulation promotes the epithelial–mesenchymal transition of HCC cells by regulating F-actin remodeling. However, the role of CAPZA1 in enhancing the invasiveness of HCC cells and the mechanism underlying its low expression in this context remain unclear. Therefore, in the present study, we investigated the molecular mechanism underlying the downregulated CAPZA1 expression and its role in enhancing the invasiveness of HCC cells.

Methods

The molecular mechanism of TGF-β-induced low CAPZA1 expression was explored using in vitro and in vivo models. RNA interference and lentiviral infection were used to modulate CAPZA1 expression, and plasmid transfection was used to modulate GATA3 expression. We confirmed the transcriptional regulation of CAPZA1 by GATA3 through a ChIP assay. Additionally, we employed a FITC-gelatin degradation experiment to evaluate the invasiveness of HCC cells. Immunofluorescence analysis was used to examine the co-localization of F-actin with cortactin, as well as of F-actin with black spots in FITC-gelatin, thereby quantifying invadopodia of HCC cells. Finally, we observed the effect of the TGF-β/GATA3/CAPZA signaling pathway on HCC metastasis by inhibiting TGF-β with small-molecule inhibitors in nude mice.

Results

Downregulation of CAPZA1 promoted the invasiveness of HCC cells by regulating invadopodia marker expression, quantity, and function. GATA3 was identified as a transcription factor that regulates CAPZA1 expression, and TGF-β inhibited CAPZA1 expression by inducing low GATA3 expression. The small-molecule inhibitor SB431542, which targets the TGF-β signaling pathway, effectively suppressed HCC metastasis in nude mice and concurrently inhibited CAPZA expression in HCC tissues.

Conclusions

TGF-β lowers the expression of the transcription factor GATA3, thereby downregulating CAPZA1 expression and enhancing the invasiveness of HCC cells, possibly by regulating invadopodia formation. Targeting the TGF-β/GATA3/CAPZA1 signaling pathway can effectively inhibit HCC metastasis.