Enhanced Effect Of Epidermal Growth Factor In Chemotherapy Sensitivity Of Colorectal Cancer: Study In Vitro

Objective:To explore the effect of epidermal growth factor in chemotherapy of colorectal cancer and discuss its possible mechanism.Methods:Studied in vitro, colorectal carcinoma cell line Caco-2 was treated with different concentrations of EGF(0.1,1,5,10,50ng/ml), after 24h,48,72h, the survive rate of Caco-2 was measured by MTT method, to observe the best concentration and time effect of EGF to the growth of the cell. Caco-2 was pretreated with EGF for 24h and without EGF, the change of IC50 of 5-Fu,Oxaliplatin,Irinotecan to cell was detected. Different groups were made:①C ontrol group②E GF③5 -Fu④5 -Fu+EGF⑤Oxaliplatin⑥Oxaliplatin+EGF⑦Irinotecan⑧Irinotecan+EGF(the concentration of EGF is 5 ng/ml and pretreated for 24h ). AnnexinV-PI Flow cytometry analysis was used to detect the rate of apoptosis of Caco-2 which with treated by EGF and chemotherapy drugs.Cyclins/DNA multiparameter flow cytometry studied the effect of EGF to the cell cycle and discuss its possible mechanism.Result: When the concentration is 1 to 50 ng/ml, EGF has the notice stimulation to the Caco-2(P<0.05), 5ng/ml,treated for 24h, the survive rate of Caco-2 enhanced 23.1±0.54%, this effect weakened for the higher concentration and the prolong treated time. The IC50 of 5-Fu,Oxaliplatin,Irinotecan to Caco-2 were 53.23,5.12,33.47 ug/ml, while pretreated with 5ng/ml EGF for 24h, they were 45.12,3.81,27.98 ug/ml. AnnexinV-PI Flow cytometry analysis the the rate of apoptosis of Caco-2: Control group: 6.75±0.64%,EGF: 2.73±0.36%,5-Fu:37.65±1.84%,5-Fu+ EGF:60.54±2.12%; Oxaliplatin:51.11±1.89%,Oxaliplatin +EGF:69.23±2.36%; Irinotecan:41.78±1.68%,Irinotecan +EGF:66.14±2.01%. Cyclins/DNA multiparameter flow cytometry detect the cell cycle, the rate of G0: Control group: 67.64±2.36%,EGF: 35.95±1.54%,5-Fu:49.90±1.68%,5-Fu+ EGF:32.51±1.94%; Oxaliplatin:42.07±1.85%,Oxaliplatin +EGF:14.46±2.54% Irinotecan:49.00±2.35%,Irinotecan +EGF:24.22±2.12%。Conclusion: EGF can stimulate Caco-2 grow, cell treated with EGF of 5ng/ml for 24h has the strongest effect and chemotherapy sensitivity was notice enhanced. This may be EGF can stimulate G0 phase of Caco-2 for reentry in the cell cycle to enhance the response to Chemotherapy...