BACKGROUND AND OBJECTIVEAs chemotherapy is generally used in the clinical treatment of cancer, the problem of multidrug resistance (MDR) of tumors against the chemotherapeutic agents becomes more and more serious. It has been the major cause for the failure of the chemotherapy. We detected the expressions of beta-catenin and tumor drug resistance related proteins, MRP2, P-gp, and Bcl-2, in esophageal squamous cell carcinoma (ESCC) to explore their function and correlation in the occurrence and development of MDR in ESCC.

METHODSWe used the tissue microarray technique, immunohistochemistry, and image analysis methods to detect the expressions of MRP2, P-gp, beta-catenin, and Bcl-2 proteins and analyze their relationships with clinical data in a ESCC tissue microarray consisting of 582 specimens of ESCC, 294 specimens of normal mucosa, 92 specimens of basal cell hyperplasia, and 87 specimens of dysplasia adjacent to cancer tissue.

RESULTSThe integral optical density (IOD) of MRP2 and Bcl-2, which was 195.7 +/- 175.9 x 10(3)) and 90.5 +/- 112.5 x 10(3)), respectively, was significantly higher in ESCC than in normal mucosa, which was 104.8 +/- 86.1 x103) and 25.2 +/- 46.6 x 10(3)), respectively (P < 0.01). The IOD of P-gp and beta-catenin, which was 57.7 +/- 75.5 x 10(3)) and 32.0 +/- 47.0 x 10(3)) respectively, was significantly lower in ESCC than in normal mucosa, which was 114.8 +/- 106.6 x 10(3)) and 46.1 +/- 35.7 x 10(3)), respectively (P < 0.01). According to the following order, well differentiated moderately differentiated poorly differentiated, the IOD of MRP2 increased in ESCC (P < 0.01). The IOD of beta-catenin was higher in poorly differentiated ESCC than in well or moderately differentiated ESCC (P < 0.01). The IOD of Bcl-2 was lower in well differentiated ESCC than in poorly and moderately differentiated ESCC (P < 0.01). The IOD of beta-catenin and Bcl-2 was higher in the ESCC of specimens with infiltration depths that were in membrane mucosa than those in the muscular layer or serous coat (P < 0.01). The IOD of Bcl-2 was significantly higher in cases with lymph node metastasis than in cases without (P < 0.01). Positive correlations which were respectively between the expressions of P-gp and MRP2, the expressions of P-gp and Bcl-2 were found (r = 0.288 and r = 0.253, respectively, P < 0.01).

CONCLUSIONSMRP2, P-gp, and Bcl-2 may be taken as prognostic factors for MDR of ESCC. beta-catenin may play an important role in carcinogenesis and progression of ESCC.