Pine pollen reverses the function of hepatocellular carcinoma by inhibiting α-Enolase mediated PI3K/AKT signaling pathway.

Objective: This study aimed to investigate the influence of pine pollen (PP) on hepatocellular carcinoma (HCC) behavior in vitro and in vivo and explore its mechanism of action by focusing on the phosphatidylinositol 3-kinase/protein serine-threonine kinase (PI3K/AKT) signaling pathway and α-Enolase (ENO1) gene expression.

Methods: We performed a bioinformatics analysis of ENO1. HCC cells overexpressing ENO1 were developed by lentivirus transfection. Cell proliferation, invasion, and migration were assessed using the cell cytotoxicity kit-8 assay, transwell assay, cell scratch test, and ENO1 inhibiting proliferation experiment. Protein expression was analyzed using Western blot. The in vivo effects of PP on HCC xenografts were also assessed in mice. The serum of nude mice in each group was analyzed for alanine aminotransferase (ALT), aspartate aminotransferase (AST), and AST/ALT. The tumor blocks of nude mice were weighed, and proteins were extracted for Western blot.

Results: Compared to normal cells, the phosphorylation of ENO1 at the S27 site was most significant in HCC cells and was closely related to cell proliferation. In vitro, the PP solution inhibited the proliferation, invasion, and migration of ENO1 overexpressing cells compared with empty-vector-transfected cells. In mice bearing HCC, PP injection inhibited the overexpression of ENO1, affected serum ALT, AST, and AST/ALT levels, and reduced tumor weight. However, the expression of proliferation-related proteins in tumors overexpressing ENO1 was higher than in empty transfected tumors.

Conclusion: PP inhibits HCC by regulating the expression of ENO1 and MBP-1 and suppressing the PI3K/AKT pathway by inhibiting C-MYC and erb-B2 receptor tyrosine kinase 2.