Evaluation of Glutathione Peroxidase 3 Protein Expression in Clear Cell and Other Ovarian Carcinomas by Immunohistochemistry

Background & Objective: Clear cell carcinoma (CCC) is an uncommon subtype of ovarian cancer, with inherent resistance to common chemotherapy agents. Glutathione peroxidase 3 (GPX3) is one of the important mechanisms of cell defense against cell damage signals. Recent studies have suggested that suppression of the GPX3 gene increases sensitivity to Cisplatin chemotherapy drugs against ovarian clear cell carcinoma (OCCC). The present study was conducted with aim to evaluate glutathione peroxidase 3 protein expression in clear cells and other ovarian carcinomas by immunohistochemistry. Materials & Methods: Patients with the diagnosis of ovarian carcinoma, who were referred to the pathology department of Imam Khomeini Hospital, were included. Immunohistochemical staining for GPX3 was performed on the paraffin blocks. The intensity and percentage of the marker were evaluated. Results: A total of 76 patients, including 31 CCC, 33 high-grade serous carcinomas (HGSC), 10 endometrioid carcinomas, and 2 low-grade serous carcinomas were examined. The mean age of the patients was 52.06 ± 11.4 years. The mean age in the CCC group (49.9±9.6 years) and in the non-clear cell carcinoma (NCCC) group (53.5±12.5 years) was not significantly different (P=0.1). Most of the patients in the CCC group were stage 1 (63%), while in the NCCC group, most of the patients (61%) were in stage 3 (P=0.000). After immunohistochemical staining, no protein expression was seen in any of the CCC and NCCC tumoral samples. Conclusion: Immunohistochemistry is not a sensitive method to evaluate GPX3 protein expression. Studies in this field should be done by molecular or serologic evaluations.