Role of stearoyl CoA desaturase 1 in resistance of colon cancer cells to 5-fluorouracil

Abstract

Objective To construct a 5-fluorouracil (5-FU)-resistant colon cancer cell line, and to investigate the role of stearoyl CoA desaturase 1 (SCD1) in the resistance of colon cancer cells to 5-FU. Methods Drug resistance to 5-FU was induced in colon cancer cell line HCT116 by increasing the concentration intermittently and repeated inducing and screening with high concentration to produce drug-resistant cell line HCT116/5FU. The survival rates and half maximal inhibitory concentration (IC50) were measured by CCK-8 assay in HCT116, HCT116/5FU, HCT116-Control and HCT116-OE-SCD1 cells after the treatment of 5-FU. Immunohistochemical assay was employed to measure the expression of SCD1 after the fabrication of colon cancer and paracancerous tissue chips. Quantitative PCR and Western blotting were applied to detect the expression of SCD1. CCK-8 assay, plate clone formation and crystal violet staining were used to detect cell survival status. The apoptotic rates were detected by AnnexinV-FITC/PI double staining. HCT116-Control and HCT116-OE-SCD1 subcutaneous xenograft models in nude mice were established to observe the effect of SCD1 on tumor growth. Western blotting was carried out to detect the expression of apoptosis-related proteins. Results The IC50 value of 5-FU was 0.90±0.06 μg/mL in HCT116 cells, and 15.02±0.81 μg/mL in HCT116/5FU cells, with a multiple of resistance about 16.7 times. The expression of SCD1 was higher in drug resistant colon cancer tissues than in common colon cancer tissues and corresponding paracancerous tissues. And its expression level was also higher in HCT116/5FU cells than HCT116 cells. Overexpression of SCD1 reduced the apoptotic rate of colon cancer cells(P < 0.01). Xenograft nude mouse model indicated that SCD1 overexpression enhanced the resistance of colon cancer cells to 5-FU. After 48 h of 5-FU treatment, the expression of bcl-2 and caspase3 were lower in HCT116-OE-SCD1 group than HCT116-Control group(P < 0.01). Conclusion The 5-FU-resistant model of colon cancer HCT116/5FU cells is successfully established. SCD1 promotes the resistance to 5-FU in colon cancer cells

Keywords

• drug resistance
• 5-fluorouracil
• colon cancer
• stearoyl coa desaturase 1