Poly(ADP-ribose) polymerase (PARP) and DNA-fragmentation factor (DFF45): Expression and correlation in normal, hyperplastic and neoplastic endometrial tissues

This study evaluated the immunohistochemical expression of poly(ADP-ribose) polymerase (PARP) and DNA fragmentation factor 45 (DFF45) in normal endometria (NE, n=13), non-atypical (NAH, n=22) and atypical hyperplasia (AH, n=14), endometrioid carcinoma (EC, n=34), serous carcinoma (SC, n=10), and clear cell carcinoma (CCC, n=2). With regard to quantity and intensity of positively stained cells, immunostaining was scored as negative, low, and strong. Nuclear PARP immunoreactivity was found in all cases. If present, DFF45 immunoreactivity was detected predominantly in the nucleus and to some extent in the cytoplasm. PARP immunoreactivity increased significantly from NE via NAH to AH (P=0.0004), and decreased from AH to endometrial carcinomas (P=0.0054). DFF45 immunoreactivity increased significantly from NE to NAH and to AH (P=0.0009). No significant differences were calculated between AH and endometrial carcinomas (P=0.7495). FIGO stages and tumor grades could not be characterized by PARP and DFF45 immunoexpression (P=1.000 and 0.7383, as well as P=0.3034 and 0.7533, respectively). Pearson correlation revealed significant associations of PARP and DFF45 immunoscores for all diagnostic categories of NE, NAH, AH, EC, and SC/CCC. Immunoexpression of PARP and DFF45 is apparently altered in endometrial carcinomas as compared with non-neoplastic endometrial tissues, indicating impaired mechanisms of apoptosis in the former.