Expression of Stem Cell Markers Cd133 and OCT-4 in Rectosigmoid Adenocarcinoma and their Predictive Significance of Response to Chemoradiotherapy

Mona Abdel-Hadi, Dina Abdallah, Mounira Amer and Gehan Khedr

Colorectal carcinoma (CRC) is one of the most common cancers in the world. Preoperative radiation with concurrent chemotherapy and subsequent surgery is the standard treatment for locally advanced rectal cancer. However, the tumor response to preoperative chemoradiotherapy (pCRT) varies significantly. CSCs have been found in many human malignant tumors including rectal cancer. Several markers for CSCs have been proposed in CRC, OCT-4 and CD133 have been the most frequently researched.

This study was targeted to evaluate the immunohistochemical expression of stem cell markers OCT-4 & CD133 in rectosigmoid adenocarcinomas and correlate their expressions with the grade, stage, and response of the tumor to CRT.

The present study comprised 30 specimens of rectosigmoid adenocarcinoma. The primary antibodies used were: OCT-4 antibody, clone PA5-27438, and CD133 antibody, clone144305. Positive OCT-4 expression was observed in 12/30 cases. A significant relationship was found between OCT-4 expression and tumor stage and sex of the patients. No statistically significant relation was found between OCT-4 expression and age of the patients, tumor grade, lymph node stage, pathological response to CRT, OS, or the expression of CD133.

20/30 cases were positively stained for CD133, no significant correlation between CD133 expression and any of the clinicopathological parameters.

OCT-4 was expressed in 40% and CD133 in 66% of rectosigmoid cancers studied, so they might be involved in the development of CRC. New therapeutic perspectives based on the selective targeting of the specific population of cells expressing one of those CSCs. OCT-4 expression might be a bad prognostic indicator in rectosigmoid cancer.