Expression of muitidrug resistance-associated proteins 4 protein in colorectal cancer cell lines with different radiosensitivity

Objective To screen the radiation-resistant and radiation-sensitive cell strains from 5 colorectal cancer cell lines and observe the muitidrug resistance-associated proteins 4 (MRP4) protein expression in two cell lines,and explore the relashionship between MRP4 protein expression and radiation sensitivity.Methods Different radiation doses (0,2,4,6 and 8 Gy) were used to irradiate colonrectal cancer cell lines LOVO,DLD-1,HT-29,HCT116 and RKO,and radiation sensitive and radiation resistant cell lines were screened.Immunohistochemistry was used to detect MRP4 protein expression in these two cell lines.Results Radiation sensitive and radiation resistant cell lines were LOVO and RKO separately.Their growth inhibition curve after the intervention was significantly different (P ＜0.01).For MRP4 protein expression in the radiation resistant RKO and sensitive LOVO cell lines,high expression and low expression rate was 71％ and 17％,and 29％ and 83％ separately with the difference being significant (P ＜0.01).Conclusion The low-expression of MRP4 protein in radiation-sensitive cell line LOVO and the high-expression of MRP4 protein in RKO radiation-resistant cell line reveals that MRP4 protein expression is not only related to chemotherapy resistance,but also radiotherapy resistance. Key words: Colorectal cancer;  Radiosensitivity;  Muitidrug resistance-associated proteins 4