The Molecular Mechanism Of EGFR Signal Transduction Pathway On The Proliferation Of Human Hepatocellular Carcinoma

Background:Human hepatocellular carcinoma (HCC) is the most common malignancy in the world and its incidence rate is still increasing. About 300,000 people died of this disease every year in China, that's the biggest number all over the world. The transmembrane receptor EGFR (epidermal growth factor receptor) possess the activity as RTK (receptor tyrosine kinase), that's encoded by the gene of C-erbB1. EGFR is composed of three parts, ligand-binding domain, transmembrane domain, and intracellular domain, in which the intracellular domain is the key point for the TRK activity and mediating signal transduction. EGFR expresses generally in epidermal cell and matrix cell. Clinical research indicates that overexpression of EGFR is common in lots of epitheliogenic malignant tumors, for example the breast cancer, nonsmall-cell lung cancer (NSCLC), ovarian cancer, renal carcinoma and colon carcinoma. But the role of EGFR in the development and progression of HCC cells in not confirm now. EGFR signal pathway is always closed in normal tissue, and will be activated in tumor tissue. The downstream signal transduction pathway chiefly contains Ras-ERK/MAPK, PI3K/AKT and JAK/STAT, in which the Ras-ERK/MAPK pathway correlates closely with the cell proliferation. Microwave EnVision, two-step immunohistochemical staining technique was used in this study to evaluate the expression of EGFR in HCC tissues. In addition, we treated the HuH7 cells with EGF and AG1478, a selective inhibitor of EGFR, to show the change of EGFR activity influenced on the cell proliferation. The purpose of present study was to investigate the expression of EGFR and the EGFR signal transduction pathway in HCC cells, to explore the molecular mechanism of EGFR pathway mediating the proliferation of HuH7 cell line.Objective:To investigate the expression of EGFR and the EGFR signal transduction pathway in HCC cells, and to explore the molecular mechanism of EGFR pathway mediating the proliferation of HuH7 cell line. Methods:1. Cell culture: HCC cell line HuH7 was cultured in vitro as routine.2. The expression of EGFR in HCC tissues was evaluated by immunohistochemistry (IHC).3. The treatment of HuH7 cells consisted of two parts, EGF and AG1478.4. Western blotting was employed to detect the expression of EGFR, p-EGFR and p-ERK in HuH7 cells.5. The cell viability was determined using the cell proliferation reagent CCK-8.Results:1. Among 17 cases of HCC tissues, the positive rates of EGFR detected were 100% (17/17), while the expression of EGFR in HuH7 was stronger than that in HL-7702.2. Exogenous EGF (10μg/L) enhanced the phosphorylation of ERK and EGFR, and also the growth rate of HuH7 cells at 24h. But, the effect of EGF could be totally interrupted by AG1478 (20μmol/L), a specific inhibitor of EGFR tyrosine kinase.Conclusion:Our findings suggested that the expression of EGFR shoud be positive intensively in HCC cell line HUH7, and the activation of EGFR depend upon the phosphorylation of EGFR. EGFR-ERK/MAPK signal transduction pathway might play a key role in HuH7 cells, which regulated the development and the progression of HCC cells.