Influence of UGT1A1 gene methylation level in colorectal cancer cells on the sensitivity of the chemotherapy drug CPT-11.

OBJECTIVE

To study the influence of the methylation level of UGT1A1 gene related to CPT-11 metabolic enzymes in colorectal cancer cells on the sensitivity of chemotherapy drugs.

METHODS

Test the changes in sensitivity of seven colorectal cancer cell strains that have been/not been subject to DAC treatment to CPT-11, analyze its correlation with CES2, UGT1A1 and GUSB mRNA expression according to IC50; screen the effective interference sequence of UGT1A1 siRNA, test the changes in cytotoxicity of CPT-11 after UGT1A1 siRNA is transfected, select RK0 cells and make them transfected with the chemosynthetic UGT1A1 siRNA after their UGT1A1 expression is restored with or without demethylation treatment.

RESULTS

The sensitivity of different colorectal cancer cell strains to CPT-11 showed difference (P<0.05), UGT1A1 expression in colorectal cell lines had a negative correlation with the IC50 (r=0.790648, P<0.05), the interference efficiency of the screened UGT1A1 siRNA was up to 78%. The IC50 value of siRNA decreased by nearly one time after transfected with HT-29 (P<0.01); which of methylated RK0 cells of UGT1A1 gene increased instead after the demethylation treatment. However, the IC50 value of the demethylation treatment group increased compared with the non-demethylation treatment group after UGT1A1 siRNA was transfected.

CONCLUSIONS

The cytotoxicity of CPT-11 to colorectal cancer cells has a negative correlation with UGT1A1 expression, and positive correlation with CES2 and GUSB. The specific silencing UGT1A1 gene of siRNA could significantly increase the sensitivity of CPT-11 to the chemotherapy of colorectal cancer cells. UGT1A1 methylation was an important factor affecting the chemosensitivity of CPT-11.