DNA fragmentation factor (DFF45): expression and prognostic value in serous ovarian cancer

This study investigated the expression of DNA fragmentation factor (DFF45), MIB-1, and p53 in formalin-fixed, paraffin-embedded archival tissues of 50 ovarian serous carcinomas. In addition, 10 benign serous cystadenomas and 10 serous neoplasms of low malignant potential (LMP) were included in this DFF45 immunostudy. With regard to quantity and intensity of positively stained cells, immunostaining for DFF45 was scored as low or strong. MIB-1 labeling indexes (LIs) were quantitated as the percentage of positively stained nuclei in 1000 nuclei. For p53, at least 10% of tumor cells had to display nuclear staining to consider a case positive. DFF45 staining was noted predominantly in the nucleus. Low DFF45 expression was identified in all serous cystadenomas and in LMPs, as well as in 18 (36%) ovarian serous carcinomas. The latter displayed strong expression in 32 cases (64%). DFF45 immunoreactivity increased with FIGO stage and with grade (P=0.0213 and 0.0084, respectively), as well as with p53 positivity (P=0.04), but not with MIB-1 LIs (P=0.076). A trend towards poor outcome was observed in patients whose tumors displayed high levels of DFF45 immunoexpression (P=0.0187). Apoptotic bodies were consistently DFF45-negative. This study indicates that DFF45 expression is frequently upregulated in ovarian serous carcinomas and may serve as a marker of aggressive behavior with prognostic value.