Curcumin reverses irinotecan resistance in colon cancer cell by regulation of epithelial-mesenchymal transition.

The objective of this study was to investigate the effect and the mechanism by which curcumin reverses irinotecan-induced chemotherapy resistance in colon cancer. Construction of irinotecan-resistant colon cancer model LoVo/CPT-11R cells was performed by increasing drug concentration. The Cell Counting Kit-8 assay was used to detect inhibition of proliferation; cell morphology was observed by an optical microscope. Quantitative RT-PCR and western blotting were performed to detect molecular marker expressions during epithelial-mesenchymal transition (EMT); drug-resistant cells were treated with curcumin at different concentrations and Cell Counting Kit-8 was reperformed to detect cell proliferation after treatments. Drug-resistant cells were then divided into four groups: control group, irinotecan group, curcumin group, and irinotecan+curcumin group; quantitative RT-PCR and western blotting were performed to detect molecular marker expressions during epithelial-mesenchymal transition. Flow cytometry was used to detect cell apoptosis after grouping, and apoptosis-related protein was detected by western blotting. LoVo/CPT-11R cells could survive in culture medium containing irinotecan at 60 μg/ml and the drug-resistance index was 5.69; the drug-resistant cells had a larger volume than normal cells and were poorly connected to each other. E-cadherin expression was downregulated, whereas vimentin and N-cadherin expressions were upregulated. After curcumin treatment, drug-resistant cell proliferation was significantly inhibited; in the curcumin+irinotecan treatment group, E-cadherin expression was upregulated, whereas vimentin and N-cadherin expressions were downregulated. Curcumin could significantly increase cell apoptosis. EMT is involved in the development of irinotecan resistance and curcumin can reverse this drug resistance through reversion of the EMT process.