Cells with characteristics of cancer stem/progenitor cells express the CD133 antigen in human endometrial tumors.

PURPOSE Cancer stem cells represent an attractive therapeutic target for tumor eradication. The present study aimed to determine whether CD133 expression may identify cells with characteristics of cancer stem/progenitor cells in human endometrial tumors. EXPERIMENTAL DESIGN We analyzed 113 tumor samples for CD133/1 expression by flow cytometry, immunohistochemistry, and semiquantitative reverse transcription-PCR. CD133(+) cells were isolated and used to assess phenotypic characteristics, self-renewal capacity, ability to maintain CD133 expression and form sphere-like structures in long-term cultures, sensitivity to chemotherapeutic agents, gene expression profile, and ability to initiate tumors in NOD/SCID mice. RESULTS Primary tumor samples exhibited a variable degree of immunoreactivity for CD133/1, ranging from 1.3% to 62.6%, but stained negatively for other endothelial and stem cell-associated markers. Isolated CD133(+) cells expanded up to 4.6-fold in serum-replenished cultures and coexpressed the GalNAcalpha1-O-Ser/Thr MUC-1 glycoform, a well-characterized tumor-associated antigen. Dissociated bulk tumors formed sphere-like structures; cells grown as tumor spheres maintained CD133 expression and could be propagated for up to 12 weeks. CD133(+) cells purified from endometrioid adenocarcinomas were resistant to cisplatin-induced and paclitaxel-induced cytotoxicity and expressed a peculiar gene signature consisting of high levels of matrix metalloproteases, interleukin-8, CD44, and CXCR4. When serially transplanted into NOD/SCID mice, CD133(+) cells were capable of initiating tumor formation and recapitulating the phenotype of the original tumor. CONCLUSIONS CD133 is expressed by human endometrial cancers and might represent a valuable tool to identify cells with cancer stem cell characteristics.