The Relationship Between High Drug-resistance Of Spheres From Colon Cancer Cells And The Expressions Of Related Proteins RAD51and BRCA1

Objective:To investigate the relationship between drug–resistance ofsphere–forming colon cancer cells and the expressionsof RAD51andBRCA1proteins.Methods:1. The spheres from colon cancer HCT116and SW480cells wereformed using SFM culture.2. The CD133＋populations of colon cancer sphere-forming HCT116and SW480cells and the monolayer cells were detected by FCM.3. After the colon cancer spheres and the monolayer cells were treatedwith different concentrations of5-Fu and L-OHP alone and in combination,the proliferation ability was detected by CCK-8, and IC50value wascalculated. The apoptotic rate was detected by FCM. 4. The expression levels of RAD51and BRCA1were detected byimmunofluorescence and Western blotting.Result:1. The stable colon cancer spheres from HCT116and SW480cellswere formed using SFM culture with growth factors.2. The CD133＋population proportion of colon cancer sphere-formingHCT116and SW480cells was significantly higher as compared with thatof the monolayer cells.3. The colon cancer sphere-forming HCT116and SW480cells had ahigher survival rate and a lower apoptotic rate as compared with those ofthe monolayer cells after treatment with the same concentration of5-Fu orL-OHP. The IC50values of5-Fu and L-OHP were significantly higher forthe colon cancer sphere-forming HCT116and SW480cells than those forthe monolayer cells.4. The expression levels of RAD51and BRCA1proteins wereincreased in the colon cancer sphere-forming HCT116and SW480cellsand the monolayer cells after5-Fu or L-OHP intervention. The expressionlevels of RAD51and BRCA1proteins in the colon cancer sphere-formingcells were higher than those in the monolayer cells after treatment with thesame drugs.Conclusion:1. Both HCT116and SW480cancer spheres can be generated in SFM, which are riched in CD133+cells and CSCs-like cells.2. The spheres from HCT116and SW480possess stronger drugresistance than monolayer cells.3. The high drug-resistance of colon cancer spheres may be connectedwith the involvement of HR-related proteins RAD51and BRCA1.