Objective: To study in vitro and in vivo protein expression and biological function of gene pp1158, a hepatocellular carcinoma (HCC)-related gene.
Methods: pp1158 was expressed with fusion expression vector pET-32a in E. Coli-BL21 (DE3), and rabbit anti-pp1158 fusion protein polyclonal antibody was prepared. The biological function and differential expressions of pp1158 were studied by in vitro colony formation assay nude mouse in vivo tumor formation assay of transfected BEL7402 cell line and immunohistochemistry and Western blot. Differential expression of pp1158 in human fetal tissues were examined by Northern blot.
Results: In vitro experiment showed that pp1158 inhibited colony formation rate of transfected BEL 7402 cells, with an inhibition rate of 58.3% (P < 0.01). Tumor formation assay indicated that tumor formation of pCMV-Script-1158 transfected BEL 7402 cell line was significantly inhibited (P < 0.05) as compared with that of the control group. Immunohistochemical assay showed that pp1158 was expressed in human tissue in the following sequence: normal liver >/= noncancerous liver tissue > HCC. Western blot indicated that a 60kD protein (pp1158 protein) was expressed in BEL 7402 cells transfected with pCMV-Script-pp1158 DNA, while it was detected in BEL 7402 cells transfected with pCMV-Script vector DNA. Northern blot showed pp1158 was expressed in the placenta at a very high level, heart, liver, muscle, pancreas and lung but expressed poorly in the brain and kidney.
Conclusion: pp1158 is a new candidate tumor suppressor gene of HCC.