Identification of AKT1/CTNNB1 mutations conferring cetuximab and chemotherapeutic drugs resistance in colorectal cancer treatment

Abstract

In anti-cancer therapy, the effectiveness of therapeutics is limited by mutations causing drug resistance.1KRASmutations are the only determinant for cetuximab resistance in colorectal cancer (CRC) patients.2Therefore, it is very important to determine new predictive mutations in CRC treatment.3In this study, the association of AKT1/CTNNB1mutations with the drug resistance against cetuximab and some chemotherapeutics used in the CRC treatment were investigatedin vitroby using site-directed mutagenesis, transfection, Western Blot methods, and 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) cell growth inhibition assay. The cetuximab resistance was higher in the presence of AKT1 E17K, E49K, and L52R mutations and, CTNNB1 T41A, S45F, and S33P mutations compared to that of the WT. AKT1/CTNNB1mutations were also determined to be associated with oxaliplatin, irinotecan, SN-38, and 5-fluorouracil resistance. Furthermore, mutant cell viability in oxaliplatin treatment was more effectively inhibited than that of the other drugs. These findings provide evidence that CRC patients carryingAKT1/CTNNB1mutations may have resistance to cetuximab and frequently used chemotherapeutics, and these mutations may serve as an important predictive biomarker which responsible for drug resistance.