Osteopontin expression in ovarian carcinomas and tumors of low malignant potential (LMP)

Expression of osteopontin (OPN) by ovarian tumors is not known. Neoplasms arising from the ovarian epithelium are distinguished in adenocarcinomas and borderline tumors (LMPs), which overall have a favorable prognosis even with omental implants. Tissues from primary ovarian tumors and their metastases from 30 patients (16 LMPs and 14 adenocarcinomas) were evaluated for OPN expression by immunohistochemistry, Western blotting, and in situ hybridization. OPN was weak or absent in 93% of ovarian adenocarcinomas or their metastases. In contrast, 81.5% of the LMPs and 50% of omental and lymph node implants were OPN positive (P < .028). Histological type, grade, or clinical stage did not correlate with OPN expression. Expression of OPN primarily by ovarian neoplasms with favorable prognosis is an intriguing new finding of potential importance in the pathogenesis of ovarian LMPs.