Expression of glutathione S-transferase pi (GST-pi) in human malignant ovarian tumors

Objectives: In recent years, glutathione S-transferase pi (GST-pi) has attr acted much attention and has been studied us a mechanism of multidrug resis tance of tumors to anticancer drugs. In the present study, we immunohistolo gically measured the expression of GST-pi in tumor tissues using surgical s pecimens obtained from patients with malignant ovarian tumors. Methods: Of 137 patients with malignant ovarian tumors treated and managed during a per iod of 20 years since the establishment of Tsukuha University Hospital. 117 patients were selected as subjects because of the presence of complete dat a on their clinical courses as well as paraffin blocks preserved in a good condition. GST-pi in these specimens was immunohistochemically stained to d etermine the correlation between GST-pi stainability and clinical outcomes. Stainability was graded as 0 when GST-pi was completely absent, 1 when les s than 20% of tumor cells were stained, 2 when 20-60% were stained, and 3 w hen more than 60% were stained. Results: When the correlation between stain ability and clinical outcomes was analyzed with Kaplan-Meier method, exclud ing stage Ia cases that did not receive adjuvant chemotherapy at our hospit al. significantly better clinical outcomes were observed in the low stainab le group, compared with the high stainable group (P < 0.01- 0.05, Cox-Mante l test, Wilcoxon's test). Conclusion: Since the stainability for GST-pi was high in tumors of histological types with strong resistance to anticancer drugs, and better clinical outcomes were observed in cases having a lower s tainability score, the expression of GST-pi was thought to play some role i n the resistance of malignant ovarian tumors to anticancer drugs. (C) 2001 Elsevier Science ireland Ltd. All rights reserved.