ABSTRACT
Objective To investigate the relationship between the sensitivity of colon carcinoma cells to epidermal growth factor receptor(EGFR) inhibitor,gefitinib,and the downstream proteins of EGFR.Methods The expressions of EGFR proteins of 6 colon carcinoma cell lines(Lovo,HCT116,HT29,LS174T,SW480 and SW620) were determined with immunocytochemistry staining.The inhibitory effects of gefitinib on the growth of colon carcinoma cells were assessed by MTT,and the expression levels of Akt and MAPK as well as their phosphorylated forms(p-Akt and p-MAPK) were assessed by Western blotting.Results EGFR protein expressed in all the Lovo,HCT116,HT29,LS174T and SW480 cells,and the highest expression was found in Lovo cells,but not in SW620 cells.Lovo cells showed the highest,HT29 and SW480 cells showed moderate,sensitivity to gefitinib,while the others showed more or less resistance to gefitinib.No significant difference was found between the growth inhibition and IC50 values among the 6 cell lines despite of being treated with fetal bovine serum or EGF.Akt protein existed in all the cell lines without notable difference.Lovo and SW620 cells showed the least of p-Akt expression(P
ABSTRACT
Objective To evaluate the inhibitory effects of gefitinib on the growth of colon carcinoma cells with different degree of sensitivity,and the activated status of epidermal growth factor receptor(EGFR) associated signal pathway proteins.Methods The colon carcinoma cell lines(Lovo,HCT116 and HT29) were treated with 10?mol/L of gefitinib,and flow cytometry was employed to detect the cell cycle and apoptosis.Another portion of cells were treated with 50ng/ml of epidermal growth factor(EGF) or 5?mol/L or 10 ?mol/L of EGF+gefitinib,and Western blotting was used to determine the expressions of PTEN,EGFR,AKT and MAPK,as well as their corresponding phosphorylated proteins,p-EGFR,p-AKT and p-MAPK.Results After being treated with gefitinib,the G1 phase cells and apoptosis rate increased remarkably in Lovo,slightly in HT29,while no significant change was found in HCT116.With the treatment of EGF alone,the expressions of p-EGFR,p-AKT and p-MAPK increased significantly in Lovo and HT29 cells(P0.05).Conclusions The growth of colon carcinoma cells,which are resistant to gefitinib,is not dependent on EGFR,and the activated status of signal pathway of the gefitinib-resistant cells will not be inhibited as the EGFR is blocked.The present findings suggest that sensitivity of colon carcinoma cells to gefitinib relies on EGFR as well as the activation of its downstream signal pathway.