Enhanced CD24 expression in endometrial carcinoma and its expression pattern in normal and hyperplastic endometrium

CD24 is known to be an important diagnostic and prognostic marker of several major cancers affecting females. We aimed to determine CD24 expression in normal, hyperplastic, and carcinomatous endometrium and its correlation with estrogen and progesterone receptor expression. A total of 271 cases including 62 normal/atrophic endometrium cases (47/15), 127 endometrial hyperplasia cases (51/52/24, simple/complex/atypical hyperplasia), and 82 endometrial carcinoma cases were immunohistochemically analyzed by using anti-CD24, ER, and PR antibodies that were embedded on paraffin blocks. Next, we assessed the CD24 mRNA expression in these tissues by using RT-PCR. In the normal endometrium, cyclic expression of membranous CD24 was detected during the regular menstrual cycle, i.e., down-regulation in the proliferative phase and up-regulation in the secretory phase. CD24 expression was very infrequent and weak in the atrophic endometrium. In hyperplasias and carcinomas, the expression of both membranous and cytoplasmic CD24 was found to be sharply reduced in the hyperplastic lesions and significantly enhanced in the carcinomas. In the case of carcinomas, high CD24 expression showed significant correlation with high-grade (G2 and 3) (P<0.05). In addition, an inverse correlation was apparent between CD24 and the estrogen and progesterone receptor expressions in normal and diseased endometrium. In conclusion, we demonstrated that CD24 was expressed in a cyclic pattern in the normal endometrium, and its expression was enhanced in case of endometrial carcinoma. These results suggest that CD24 may be involved in tumor progression and can be a useful diagnostic biomarker.