Sensitivity Analysis Of Colorectal Cancer Cells To Targeted Drugs And In Vivo Experiment Of Drug Combination Overcoming Resistance

Background:In recent years,tumor-targeted agents have become popular for cancer treatment due to their higher specificity and less damage to normal cells.However,the inherited and acquired resistance of targeted drug has arisen in clinical cancer treatment because of cancer heterogeneity.This prompted the researches of other new targeted drugs,as well as combined drug therapy to achieve desired effects.Our study evaluated the sensitivity of nine colorectal cancer cells to 30 tumor targeted drugs or inhibitors.Then we screened drug combinations which can overcome resistance in inherited and primary colorectal cancer cells.Furthermore,the effect of selected drug combination was investigated in vitro and in vivo.The mechanism of overcoming resistance was also analyzed.In this work,we primarily focused on the analysis of drug sensitivity and the investigation of drug combination in vivo.Objective:1.To analyze the sensitivity of nine colorectal cancer cells to 30 kinds of tumor targeted agents.2.To screen the drug combination for overcoming trametinib resistance,and to investigate the effect of the combination on the xenograft tumors of inherited and acquired colorectal cancer cell lines.Methods:1.Nine colorectal cancer cells and 30 tumor targeted agents were chosen in this study.The cell viability was determined by MTT assay.The IC₅₀0 value was calculated and used for sensitivity determination.The targeted agent was considered sensitive if the IC₅₀0 was less than or equal to 100 nM.The screening of drug combo was carried out by combining trametinib with the remaining 29 targeted agents.The concentration of each agents was kept 50 nM in the screening experiments.2.The xenograft models in nude mice were established by subcutaneous injection with inherited and quired trametinib resistance cell line SW480 and RKO-R respectively.The effect of combination on tumor growth were investigated by plot tumor growth curve.The expression of Ki67,Cleaved caspase-3,p-ERK and p-Akt in tumor tissue were also detected by immunohistochemistry.Results:1.MTT results showed that only 9 sensitive drugs in nine colorectal cancer cells,and SW480 cell was resistant to 30 tumor-targeted agents.2.In the screening of the drug combo,SW480 cell line was most sensitive to the Trametinib and GSK2126458 combination with the viability of 17.11%.3.In the xenograft models with inherited and quired trametinib resistance cell line SW480 and RKO-R,the growth of xenograft tumors in the combination group were significantly slower compared to the single-agent group.We also observed the increasing expression ofCleaved caspase-3 and reducing expression of Ki67 and the phosphorylation level of Akt and ERK in tumor tissues.Conclusions:1.Nine colorectal cancer cells were resistance to targeted agents at different level.2.The combination of trametinib and GSK2126458 could overcome the primary and acquired resistance to trametinib in colorectal cancer cell.