Does rAj-Tspin, a novel peptide from A. japonicus, exert antihepatocellular carcinoma effects via the ITGB1/ZYX/FAK/AKT signaling pathway?

rAj-Tspin, a soluble recombinant peptide from Apostichopus japonicus, can inhibit the integrin β1 (ITGB1)/FAK/AKT signaling pathway in hepatocellular carcinoma (HCC) via cell epithelial-mesenchymal transition (EMT) and apoptosis. Zyxin (ZYX) is a focal adhesion protein that is considered a novel mediator of EMT and apoptosis. However, the inhibitory mechanisms of rAj-Tspin in HCC and whether it is related to ZYX are unclear. We examined the antitumor effect of rAj-Tspin on the Huh7 human HCC cell line and on a nude mouse model generated via subcutaneous injection or orthotopic intrahepatic transplantation of Huh7 cells. Our results revealed that rAj-Tspin strikingly reduced the viability and promoted the apoptosis of Huh7 cells and inhibited HCC tumor growth in nude mice. rAj-Tspin inhibited ITGB1 and ZYX protein expression in vivo and in vitro in a dose-dependent manner. Mechanistically, the FAK/AKT signaling pathway and the proliferation and invasion of HCC cells were suppressed upon ITGB1 and ZYX knockdown. Moreover, the effect of ITGB1 overexpression on the growth of HCC cells was inhibited by rAj-Tspin. In contrast, the promoting effect of ITGB1 overexpression could be inhibited by ZYX knockdown. ZYX knockdown had no effect on ITGB1 expression. These findings suggest that ZYX is required for the indispensable role of ITGB1 in rAj-Tspin-alleviated HCC and provide an important therapeutic target for HCC. In summary, the anti-HCC effect of rAj-Tspin potentially involves the regulation of the ITGB1/ZYX/FAK/AKT pathway, which in turn impacts EMT and apoptosis.