Engrailed protein: A cancer-specific marker in epithelial ovarian cancer.

Abstract

e15517 Background: Ovarian cancer is a common malignancy, accounting for 4% of all cancers and 5% of all cancer deaths in women in the Western world. Engrailed-2 (EN2) is a homeodomain–containing transcription factor that is essential during early development. It is dysregulated in a number of cancers and its presence in urine is diagnostic of prostate cancer. We have investigated its role as a cancer-specific marker in epithelial ovarian cancer (EOC). Methods: Ovarian tumours and normal tissue were collected from patients with epithelial ovarian cancer (EOC) and tested by semi-quantitative RT-PCR as well as by immunohistochemistry. EN2 expression relative to B-actin was calculated using the Livak comparative Ct method (2-DDCt). All slides were scored on a 0-3 scale based on intensity, by two independent assessors. Results: We examined 118 EOC specimens, of which 64 were tested by immunohistochemistry and 54 by RT-PCR. 89 (75.42%) were serous, 18 (15.25%) endometroid, 7 (5.93%) mucinous, and 4 (3.39%) clear cell tumours. Normal ovarian tissue was used as a control. 104 (88.14%) tumours expressed EN2 whilst 14 (11.86%) were negative. Of the EN2 positive tumours examined using immunohistochemistry, 28 (51.85%) strongly expressed the antigen (score of 2-3), whereas 26 (48.15%) were weakly positive (score of 1). Normal tissue did not express EN2 and this difference was statistically significant (p<0.05). There was no correlation with tumour type, grade and stage. EN2 expressing mucinous tumours showed improved overall survival (p=0.0253). There was no correlation for survival or PFS for other histological subtypes. Conclusions: EN2 is a cancer-specific marker in epithelial ovarian cancer. Further work is currently ongoing to evaluate its significance in ascites, blood and urine. We plan to further evaluate its role as a diagnostic biomarker by examining blood, urine, and ascites.