ABSTRACT
AIM:To investigate the role of side population ( SP) cells in multidrug resistance of colon cancer cells and microRNA biomarkers of SP cells in colon cancer cells .METHODS:SP cells in colon cancer cells were sorted by flow cytometry .The cell viability was measured by MTT method .MicroRNA expression profiles were detected by mi-croRNA chip.MicroRNA expression was verified by real-time PCR.RESULTS:The ratios of SP cells in HCT-15, HT-29 and LoVo colon cancer cell lines were 16.75%, 13.02%and 9.52%, respectively.In all 3 colon cancer cell lines, IC50 of the antitumor drugs including 5-fluorouracil , oxaliplatin and adriamycin for the SP cells were significantly higher than those for non-SP cells (P<0.05).MicroRNA profiling showed that miR-5000-3p, miR-5009-3p and miR-552 were all up-regulated in the SP cells of all 3 colon cancer cell lines .This result was verified by real-time PCR.CONCLUSION:miR-5000-3p, miR-5009-3p and miR-552 are all up-regulated in the SP cells of colon cancer cell lines , and may be the poten-tial microRNA biomarkers of SP cells in colon cancer .