Studies On Phospholipid Changes In The Development Of Hepatocellular Carcinoma

Development of liver cancer undergoes the process of inflammation,steatosis,cirrhosis and hepatocellular carcinoma(HCC)in general.Metabolism changes took place in the process,especially disorder of lipid metabolism.Lipids play an important role in tumor cell proliferation,invasion,metastasis,and angiogenesis as an important component of cell membranes.To study the changes of lipid content in normal and cancerous livers,to understand the relationship between the regulation of lipid metabolism and the occurrence and development of liver cancer,it is hopeful to find the key nodes in the development of liver cancer,It is of great significance for the diagnosis,control and successful treatment of liver cancer.Lipidomics analysis provides us with a new way to discover the relationship between metabolic abnormalities and diseases.In this study,to explore significant phospholipids in the liver tissue in the diethylnitrosamine-induced C57BL/6 mouse model,direct infusion ESI-MS/MS was used.Multivariate data analysis methods were utilized to identify the main phospholipids.qRT-PCR and Western Blot experiments were used to find the key enzymes regulating the changes of phospholipids.H22 cancer cells with under-or over-express of key enzyme genes were used to study immune response of the macrophage incubated with tumor cells.Our results indicated that most of phospholipids(PA,PC,PE,SM,LPA,LPC,LPE)were downregulated except phosphatidylserine(PS).qRT-PCR and western blot results showed that the level of PS decarboxylase(PISD)expression significantly decreased,whereas,no significant changes were found in PS synthetase(PTDSS1,PTDSS2)in the development of liver cancer.Similar results were shown in tumor and tumor-adjacent tissues in patients.The level of PS in H22 increases after inferration with PISD siRNA,whereas the level of PS decreases when PISD is overexpressed.When H22 cells were transfected with PISD siRNA,phagocytosis function decreased after the co-incubation of macrophages RAW264.7 and H22,whereas RAW264.7 enhanced phagocytosis ability after the over-expression of PISD in H22,which may be attributed to PS induced immunosuppression.When PISD of H22 cells is overexpressed,IL-1β level in the co-culture system inccreased significantly.However,after the appropriate amount of PS was added into the co-culture system,IL-1β expression decreased.Therefore,PS plays a key role in the development of hepatocarcinogenesis,which induces the immunosuppression microenvironment to prevent the tumor cell clearance by macrophage.