Golgi Membrane Protein 73 Protein Expression And Its Role In The Development Of Liver Cancer,

Hepatocellular carcinoma (HCC) is one of the deadest cancers and half of the HCC patients are in China. Although serumα-fetoprotein (AFP) is the only reliable laboratory test for HCC diagnosis, its sensitivity is just around 45.8% (>200ng/ml) for the HCC patients at Peking Union Hospital. Recently, a group of US scientist reported that GP73 could be a better tumor marker for HCC. Our study suggests that the sensitivity and specificity of serum GP73 for HCC patients are 77% and 93%, respectively. However, the causative relationship between GP73 and liver cancer remains to be determined.To develop a diagnostic kit of GP73 for the screening of HCC patients, recombinant N-terminal and C-terminal GP73 proteins were produced to immunize animals for GP73 antibody. We first PCR amplified GP73 cDNA, then inserted the two cDNA fragments into pET29a+ plasmids to generate pET29a+-GP73N and pET29a+-GP73C vectors for the expression of his-tagged recombinant GP73 proteins. The GP73 proteins that were produced in E.coli Rosetta DE3 were purified for injection of mice and chicken to develop GP73 monoclonal and polyclonal antibodies.To delineate the role of GP73 in liver tumorigenesis, we took genetic approach to overexpress GP73 in GP73 low-expression liver cancer cell lines. Human GP73 cDNA was PCR amplified, digested, and then inserted into a retroviral expression vector pLXIN-Hyg. The pLXIN-Hyg-GP73 plasmids were transfected into retroviral packaging cell line PT67 cells to produce pLXIN-Hyg-GP73 virus. HepG2 cells were transduced with either pLXIN-Hyg-GP73 virus or pLXIN-Hyg control virus. Since the GP73 over-expressing HepG2 cells grow faster than control cells, we suggest that GP73 may promote hepatic tumorgenesis.