6%), mucous adenocarcinoma in 6 cases (10.2%) and unknown pathological type in 4 cases

(6.8%). Regents The reagents used in this study were rabbit anti-MRP1 (bs-0657R, 1:300 dilution), rabbit anti-pGP/MDR1/gp170 (bs-0563R, 1:300 dilution), rabbit anti-LRP (bs-0661R, 1:300 dilution) and Biotin conguated Goat Anti-rabbit IgG, all obtained from Beijing Biosynthesis Biotechnology Corporation (Beijing, China). Bovine serum albumin (BSA, 2%), IHC Biotin Block Kit, Streptavidin-Peroxidase and diaminobenzidine (DAB) were from Fujian Maixin Biotechnology Corporation (Fuzhou, China). Immunohistochemistry Immunolocalization of MDR markers were performed according to the streptavidin-biotin peroxidase complex method by Truong [7]. Tissue slides were first deparaffinized in xylol, ethanol, and water, and then endogenous peroxidase CYC202 research buy activity was blocked by immersion in 3% H2O2 in methanol for 10 min to prevent any nonspecific binding. For staining, the slides were pretreated in 0.01 M citrate buffer (pH 6.0) and heated in a microwave

oven (98°C) for 10 min. After blocking with BSA, the slides were incubated with the primary antibodies for P-gp, LRP and MRP for 90 min at 37°C, then PS-341 incubated with the secondary antibody (biotin-labeled anti-rabbit IgG goat antibody) for 15 min at 37°C, and finally incubated with peroxidase-labeled streptavidin for 15 min. The reaction products were visualized with diaminobenzidine. Positive cells were stained brownish granules. Ten high power fields in each slide were selected randomly and observed double blind by two investigators. The staining score of each section were calculated by staining

intensity and positive rate of cancer cells. For the quantification of staining intensity, the score of no staining, weak staining, moderate staining and strong staining was 0, 1, 2 and 3 respectively. Positive rate score of cancer cells was: 0-10% was recorded as 0; 10-30% was recorded as 1; 30-50% was recorded as 2; 50-75% were recorded as 3; >75% were recorded as 4. TCL The sum of scores was computed as the score of staining intensity added the score of the positive rate of cancer cells. Then it was graded according the sum of scores: 0-1 (-); 2-3 (+); 4-5 (++); 6-7 (+++). Statistical Analysis All the experiment data is integrated into a comprehensive data set. Numerical data were recorded directly and measurement data were described as median and range. We analyzed categorical variables using the Pearson Chis-square test and Gamma test. Statistical analysis was performed on SPSS software version 13.0 (SPSS Inc. Chicago, IL), and P < 0.05 was considered as statistically significant. Results Location and distribution of P-gp, LRP and MRP There was a clear background without nonspecific staining in negative control slides (Fig 1A). The three proteins were stained brownish granules, with P-gp mainly located on the membrane and cytoplasm (Fig 1B), LRP on peri-nuclear cytoplasm (Fig 1C), and MRP on the membrane and cytoplasm (Fig 1D).