| IntroductionMultidrug resistance ( MDR) is the protection of a tumor cell population a-gainst numerous drugs differing in chemical structure and mechanisms of influence on the cells. MDR is one of the major causes of failures of chemotherapy of human malignancies. The MDR phenotype is a well-studied subject that has been recognized as a determinant underlying specific types of drug resistance in human cancer. It is clear that the P-glycoprotein ( P-gp) plays a major role in MDR, P-gp functions as an ATP-driven active efflux pump for many natural products and chemotherapeutic drugs. The glutathione transferases (GSTs; also known as glutathione S-transferases) are major phase II detoxification enzymes found mainly in the cytosol. The function of the GST enzymes has traditionally been considered to be the detoxication of electrophiles by glutathione conjugation. The p53 tumor suppressor acts to integrate multiple stress signals into a series of diverse antiproliferative responses. One of the most important p53 functions is its ability to activate apoptosis, and disruption of this process can promote tumor progression and chemoresistance. Extensive studies indicate that both p53 and multidrug transporters play important roles in chemoresistance. However, despite being the subject of intense study, this p53-MDR relationship remains unclear in human cancers.To analyze the relationships between the expression of P-gp,GST-,p53 and clinicopathological feature of gallbladder carcinoma. Forty nine gallbladdercarcinoma specimens were evaluated for P-gp , GST- expression and p53-stained by immunohistochemical methods.Materials1. MaterialsForty-nine surgically resected and paraffin-embedded samples of gallbladder carcinoma in the years 1999-2001 were collected from the First Affiliated Hospital and the Second Affiliated Hospital of China Medical University. The patients, mean age was 58. 7 years old and the ratio of male to female was 24 to 25. None of them had any preoperative radiochemotherapy. Histologically, all of them are adenocarcinoma, 16(32.7%) were highly differentiated, 17(34. 7%) moderately-differentiated, 10(20.4%) poorly-differentiated, 6 papillary adenocarcinoma. 36 cases had local lymph node metastasis. According Nevin grading criteria, the clinical grade distribution was grade S1, S2, S3 in 19(38. 8% ) cases, Grade S4, S5 30(61.2% ) cases. In addition, the lymph node status were known for 27(55. 1% ).2. ReagentsMouse monoclonal antiboby against P-gp,GST-,p53 and SP immunohistochemical reagent box ready to use were purchased from Maixin-Bio Co, Fuzhou, China.Methods1. ImmunohistochemistryFour micrometer-thick sections were cut from formalin-fixed, paraffin-embedded surgical specimens from 49 cases of gallbladder carcinoma. Briefly, slides were deparaffinized, rehydrated, and treated with 3% H202 for 10 min to quench endogenous peroxidase activity. Nonspecific bindings were blocked by treating slides with normal rabbit serum for 30 mins. The sections were incubated overnight at 4 C in moisture chambers with a battery of Abs including anti-P-gp and anti- GST-ir and anti-p53 , and those in the control group were dyedwith the first antibody substituted by PBS. A positive control slide were always included in each immunostaining.2. Evaluation of StainingThe slides were evaluated under a transmission light microscope by two separate investigators in a blind manner. For P-gp and GST-, Extent of staining was scored as <5% ( - ) ,5% -30% ( + ) ,30% -75% ( ++ ) , >75% ( 4++ ) according to the percentages of the positive staining areas in relation to the whole carcinoma area. For p53, counts were made as < 10% ( - ) , 10% - 25% ( +),26% -50%( ++), >50%( +++).3. Statistical AnalysisStatistical analysis was performed using SPSS version 10.0. The relationship between P-gp,GST-n\p53 expression and clinicopathological factors was examined by chi-square test. The Spearman rank-order correlation coefficient was used to assess the relation among P-gp,GST- and p53. Stat...
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