Association between polymorphisms and XELIRI and XELOX chemoresistance in Saudi patients with colorectal cancer.

Multidrug resistance member 1 (MDR1) is located on chromosome 7 and encodes P-glycoprotein, which is universally accepted as a drug resistance biomarker. polymorphisms can alter protein expression or function, which has been previously reported to associate with various types of malignancies, such as colorectal cancer (CRC). Therefore, the present study aimed to determine the effects of polymorphisms on drug responses of Saudi patients with CRC. DNA samples were obtained from 62 patients with CRC and 100 healthy controls. Genotypes and allele frequencies of single nucleotide polymorphisms (SNPs) G2677T and T1236C were determined using the PCR-restriction fragment length polymorphism procedure. The results showed no significant differences in the genotype distribution and allele frequency of T1236C between patients with CRC and controls. However, G2677T was found to serve a highly significant role in protecting against the progression of CRC. In addition, none of the genotypes in SNPs T1236C and G2677T was found to affect chemoresistance to XELIRI and XELOX. In conclusion, although T1236C in the gene is not associated with CRC risk, G2677T protects against the development of CRC. Neither of the SNPs tested were associated with the risk of chemoresistance. Therefore, these two SNPs cannot be used as molecular markers for predicting drug response in patients with CRC.