Transforming growth factor beta1 gene variation Leu10Pro affects secretion and function in hepatic cells.

ABSTRACT

BACKGROUND: Our previous work revealed transforming growth factor beta1 (TGFß1) gene polymorphisms are associated with susceptibility to hepatocellular carcinoma and liver cirrhosis. However, no further study of functional substitution in hepatic cells has yet been reported. AIMS: This study was designed to uncover the functional mechanisms of TGFß1 gene polymorphisms in the pathogenesis of liver diseases. METHODS: Two recombinant TGFß1 expression plasmids containing TGFß1 codon 10 Leu/Pro variation were constructed with CMV promoter and transfected into human hepatoma cell lines (HepG2 and SMMU 7721), hepatic stellate cells (LX-2), and immortalized hepatocytes (L02). The secretion capacities of TGFß1 protein in the transfected cells were determined by ELISA. Apoptosis, proliferative activity, and expression of CD 105, CD83, and CD80 were also measured by use of flow cytometry. RESULTS: The ELISA results showed that cells transfected with CMV-Pro10 were more capable of TGFß1 secretion than those transfected with CMV-Leu10. Functionally, CMV-Pro10 was more apoptosis-protective and induced more proliferation than CMV-Leu10 in transfected hepatic cells. Pro10 up-regulated expression of CD105 and down-regulated expression of CD83. CONCLUSIONS: TGFß1 gene Leu10Pro variation in signal peptide has significant effects on TGFß1 secretion and functions in hepatic cells.