Expression of cancer stem cell markers CD24, EPHA1 and CD9 and their correlation with clinical outcome in epithelial ovarian tumours.

Abstract

There has been variability between laboratories in the identification of cancer stem cells (CSCs) markers for epithelial ovarian cancer (EOC). We have evaluated three new surface markers for EOC to identify CSCs precisely. Three new putative CSCs specific surface markers CD9, CD24 and EPHA1 identified by a bioinformatics approach were evaluated in normal ovary, fallopian tube and ovarian tumours. The expression of CD9 alone was observed in normal ovarian surface epithelium and fallopian tube whereas CD24 and EPHA1 were not expressed (n= 5). CD24 was expressed in all tumours (N= 101) while CD9 and EPHA1 were expressed in 89 and 71 tumours, respectively. The statistical analysis showed significant correlation of the stage of the disease (p< 0.0001), type of surgery (p< 0.0001) and residual disease (p< 0.0001) with overall survival. Although expression of CD9, CD24 and EPHA1 was observed in the majority of tumours there was no significant correlation with outcome. In patients who underwent primary surgery, increased expression of CD24 significantly correlated with poor survival. The expression of CD24 was significantly reduced (p< 0.002) upon analysis of paired sections from patients prior to surgery and at interval debulking surgery (n= 16). These findings suggest that overexpression of these new markers may be useful in identifying and targeting ovarian CSCs and CD24 may be a putative CSCs marker in ovarian cancer.