Regulating effect of rhGH on GHR of Bel-7402 human hepatic carcinoma cell lines in vitro

Abstract

Objective To investigate the effect of rhGH on GHR of Bel-7402 human hepatic carcinoma cell lines in vitro.Methods Radioreceptor assay was used to detect the GHR expression of the Bel-7402 human hepatic carcinoma cell lines and its relation to rhGH of different concentrations(0,1,10,100,1000,10 000 ng/ml).Horseradish peroxidase method was used to observe the changes of insulin-like growth factor Ⅰ (IGF-Ⅰ) in the supernatant of 7402 hepatic carcinoma cell line,Tumor cell count,thiazole blue chromatometry were introduced to determine the sensibility of Bel-7402 to the rhGH of different concentrations.Growth rate of tumor cells was calculated.The changes of cell proportion at each cell phase,cell proliferation index (PI) and apoptosis rate were calculated by flow cytometry.Results Radioreceptor assay confirmed that 7402 hepatic carcinoma cell line expressed GHR.Twenty-four hours after rhGH injection,GHR site quantities in the 10 ng/ml and 100 ng/ml group were significantly higher than that in the control group.Meanwhile,they were signifieantly lower in the 1000 ng/ml group than in the control group.After rhGH injection for 24 and 48 h,concentration of IGF-Ⅰ in the supernatant of 7402 hepatic carcinoma cell line was significantly higher in the 100 ng/ml group than in the control group(P<0.05).It also showed that rhGH had some effects on the growth of 7402 hepatic carcinoma cell lines.The strongest effect of enhancing proliferation of hepatic carcinoma cells was found at the concentration of 100 ng/ml rhGH (P<0.05,compared with control group) and other concentrations of it only had limited positive effects as compared with it.FCM showed that the cell ratio in S phase cell cycle and PI in study group were both significantly higher than those of the control group 48 hours after using rhGH.G2-M phase fractions in 10 ng/ml group and 100 ng/ml group were significantly higher as compared with control group.The apoptosis rate of each treatment group had no statistical differences as compared with the control group.Conclusion Definiteconcentrations of rhGH might have stimulating effects on the growth,can enhance synthesis of DNA and promote proliferation of 7402 cells line in vitro.The possible mechanism might be that rhGH can up-regulate GHR expression,which consequently enhances IGF expression and finally promotes cell line proliferation. Key words: Carcinoma,hepatocellular; Growth Hormone; Growth Hormone Receptor; Radiorecptor Assay; Cell culture