Preliminary study on establishment of a VCR-resistant colon carcinoma cell line and its underlying mechanism of drug-resistance.

Objective:To establish a vincristine (VCR)-resistant colon carcinoma cell line and explore the mechanism for drug resistance. Methods:The VCR-resistant colon carcinoma cell line was established by exposing the cells to the increasing concentrations of VCR. The MTT assay was used to detect the cytotoxicity. Cell cycle was detected by propidium iodide (PI) fluorescence staining. Flow cytometry was used to detect the P-gp on the surface of the cells. The intracellular concentrations of DOX and VCR were detected by fluorospectrophotometer and high performance liquid chromatography (HPLC),respectively. Expressions of multidrug resistance gene MDR1 and MRP1 were assessed by RT-PCR. Results:The cell double time and the cell cycle of HCT-8/VCR cells were similar to that of sensitive HCT-8 cells. The resistance of HCT8/VCR cells to VCR was 19.7 fold of HCT-8 cells. HCT-8/VCR displayed different resistance to other four anticancer drugs. The intracellular concentrations of DOX and VCR in HCT-8/VCR cells were significantly decreased (P0.01). The expressions of P-gp and MDR1 mRNA were significantly increased but the expression of MRP1 had no significant change in HCT-8/VCR cells (P0.01). Conclusion:A VCR-resistant colon cancer HCT-8/VCR cell line was established. The mechanism is related to the overexpression of P-gp thereby causing the increased efflux of exocytosis. We speculate that HCT-8/VCR could be used in the study of P-gp targeted multidrug resistance reversing agents.