[Expression of P-glycoprotein and lung resistance protein in breast carcinoma and its relationship with prognosis].

BACKGROUND & OBJECTIVE: The multidrug resistance of tumor cells is the reason to failure of chemotherapy. The overexpression of P-glycoprotein (P-gp) and lung resistance protein (LRP) play important roles in the multidrug resistance of breast carcinoma. The objective of this study was to investigate the expression of P-gp and LRP in breast carcinoma and its relationship with prognosis. METHODS: Immunohistochemical assay with the LSAB immunostaining technique was used to determine protein expression of P-gp and LRP in the specimens of paraffin-embedded tissues from 151 cases of breast carcinoma and 40 normal breast tissues (control). The results were evaluated on the basis of clinical pathological factors and the survival time of these cases. RESULTS: The expression of P-gp were found in 62 (40.8%) of the breast carcinoma samples and in 1 (2.5%) of control samples. The difference between the two groups was statistically significant (Chi(2)=21.27,P< 0.01). The expression of LRP were found in 121 (80.1%) of the breast carcinoma samples and in 22 (55.0%) of control samples. The difference between the two groups was statistically significant (Chi(2)=10.62,P< 0.01). The expression of P-gp were irrelative to age,tumor size,histotype,lymph nodes metastasis,tissue grading,clinical staging, ER condition,and prognosis. The expression of LRP were found in 62 (88.6%) of 70 cases with positive lymph nodes and 59 (72.8%) of 81 cases with negative lymph nodes. The difference between the two groups was statistically significant (Chi(2)=4.891, P< 0.05). The expression of P-gp were found in 55 (45.5%) of breast carcinomas with positive immunohistochemical reaction of LRP protein; while the expression of P-gp were found in 7(23.3%) of breast carcinomas with negative immunohistochemical reaction of LRP protein. The difference between the two groups was statistically significant (Chi(2)=3.990,P< 0.05). The expression of LRP were positively correlated with the lymph nodes metastases (r=0.197, P< 0.05) and the expression of P-gp (r=0.179,P< 0.05) and irrelative to age tumor size, histotype, lymph nodes metastases, tissue grading,clinical staging, and ER condition. Univariate analysis demonstrated worse disease-free survival in the patients with positive LRP than in those with negative LRP (Chi(2)=6.892,P< 0.01). Multivariate analysis of clinical and pathological data by Cox regression method did not demonstrated that both expression of P-gp and LRP were independent factors affecting the survival of breast carcinoma patients. CONCLUSION: The expression of P-gp and LRP have their characteristics and dissimilarity clinical significance in breast carcinoma tissues. The expression of LRP may correlate not only with MDR but also the lymph nodes metastases,prognosis and expression of P-gp in breast carcinoma tissues.