PID1 promotes HCC development through regulating TME and inhibiting inflammatory factors induced apoptosis

Abstract

Abstract Objective: PID1 (Phosphotyrosine interaction domain containing 1), an obesity related gene, was reported to induce insulin resistance and play a vital role in lipid metabolism in liver. However, its influence on HCC (hepatocelluar cancer) have not been full clarified. Here, we aims to investigate the mechanism of PID1 in favoring HCC development. Method: Hydrodynamic injection was applied to overexpress PID1 specifically in liver. Adaptive immunity was evaluated through flow cytometry. Lipids metabolism was determined by metabonomics. Western blotting was utilized to determine the effects of PID1 on PI3K/AKT and RAS/RAF/ERK pathway. Result: Overexpression of PID1 specifically in liver induced HCC development within 16 weeks. The frequency of CD4+ and CD8+ T cells decreased whereas the ratio of Gr1+CD11b+ cells increased in mice bearing PID1 plasmid hydrodynamic injection. Moreover, PID1 induced liver metabolism disorder, resulted in upregulation of TG, TC, NEFA, LDL-C as well as lactate levels, thereby involved in regulating TME (tumor microenvironment) and depressed adaptive immunity. Importantly, PID1 inhibited PI3K/AKT pathway, thus restrained phosphorylation of c-RAF on ser259 site induced by p-AKT and promoted phosphorylation of c-RAF on ser338 site, leading to activation of RAS/RAF/ERK pathway. Activated c-RAF targeted to mitochondria to decrease ROS level, which alleviated toxic effect of inflammatory factors and favored HCC cells survival. Conclusion: Our results demonstrated that PID1 provoked HCC development through regulating TME to depress adaptive immunity and inhibiting apoptosis induced by inflammatory factors.