The clinical significance of drug resistance-associated protein (DRP) expression in primary breast carcinoma

Objective:To investigate the expression of multidrug resistance gene production P-Glycoprotein (PGP),multidrug resistance-associated protein (MRP1), lung resistance-related protein (LRP), and breast cancer resistance protein (BCRP) in primary breast carcinoma, and to determine whether such the expression can predict survival.Methods:Expression of the four proteins in 50 breast cancer patients was determined by immunohiostochemistry on formalin-fixed, paraffin-embedded tumor section. The relationship between the expression of DRP and the clinicpathological characteristics, and the prognosis of breast cancer patients were also analyzed.Results:(1)PGP expression was observed in 41 of 50(82.0%),MRP1 in 43 of 50(86.0%),LRP in 40 of 50(80.0%),and BCRP in 29 of 50(58.0%)tumors. (2)MRP1 expression was more frequently observed in patients with lymph node metastasis(P0.05), and did BCRP expression in patients with hormone receptor positive (P0.05). No relation can be established between expression of PGP, MRP1, LRP, BCRP, and other clinicopathological parameters (P0.05).(3) Kaplan-Meier analyses revealed that the four proteins were colsely associated with disease-free survival (DFS), however PGP expression also associated with overall survival (OS) (P0.05) and didn't the other protein (P0.05).(4)In multivariate Cox regression analyses, only tumor size and lymph node metastasis were independent prognostic factor for DFS and OS(P0.05).In addition, PGP was independent prognostic factor for OS (P0.01).Conclusion:Our results suggested that PGP, MRP1, LRP and BCRP were frequently expression in primary breast carcinoma, and PGP might be used as one of the markers for poor prognosis in patients with breast cancer.