Myeloperoxidase: A potential marker in low-grade epithelial ovarian carcinoma.

Abstract

e15531 Background: Myeloperoxidase (MPO) is a heme protein synthesized during myeloid differentiation. It is an enzymatic mediator of several inflammatory cascades. A link between inflammation and cancer has long been recognized. We have detected MPO expression in a number of epithelial ovarian cancer cell lines and found that MPO silencing affects cancer cell apoptosis. The aim of this study is to analyze the pattern of MPO expression in a cohort of ovarian carcinomas (OC) (Type I and Type II). Methods: Using our database, we identified 210 patients diagnosed with OC (1992-2002). Paraffin blocks were available for only 175 cases. Patients data and tumor characteristics were retrieved from a review of medical records and SEER database. Tissue microarray sections were immunostained for MPO using DAKO antibody A0398. Cases were categorized as Type I and Type II based on histopathology review and FIGO criteria. 20 benign ovarian specimens, obtained from cases that had salpingo-oophorectomy for benign uterine pathology were used as a control. Cases were considered positive when stain occurred in > 10% of the tumor cells. Statistical analysis was calculated using Chi-square and T test. Results: Of 175 patients, 53 cases were Type I and 122 were Type II. 74% of the cases were serous, 6% mucinous, 4.5% clear cell, 4% mixed serous and mucinous, and 1.5% endometriod. MPO expression was assessed by analyzing cytoplasmic granular staining in tumor cells. Positive staining was noted in endothelial cells and neutrophils, which were used as internal control. MPO expression was significantly more frequent in Type I tumors. In fact, this was noted in 68% in Type I tumors comparing to 38% of Type II cases (p=0.00). On the other hand, no expression was seen in the control benign specimens. Conclusions: MPO expression is detected in ovarian carcinoma but is more frequent in Type 1 tumors. The significance of this expression in the pathogenesis and progression of OC deserve further investigation. Type I (%) Type II (%) Total (%) (MPO) negative 17 (32) 76 (62) 93 (53) (MPO) positive 36 (68) 46 (38) 82 (47) Total 53 122 175 (100) No significant financial relationships to disclose.