OCT4 EXPRESSION WAS INCREASED IN RESISTANT CANCER STEM CELL-LIKE SUBPOPULATION IN COLORECTAL CANCER

GALLINO J; LLOYD R; BATALLA M; CERDA M; GIANNONI F; CONDE A; POLICASTRO L

Buenos Aires

Congreso; Reunion conjunta de las sociedades de biociencias; 2017

Radiochemoresistance of tumors has been associated with the presence of a smallsubpopulation of tumor cells called cancer stem cells (CSCs). These cells had been shownnot only linked with high resistance to chemotherapeutic drugs but also are associated withmetastatic recurrences. Embryonic markers such as Oct-4,Nanog, Sox-2 are associated withresistance to chemotherapeutic drugs in some cancer. However, little has been reportedabout the expression of these embryonic markers in colorectal (CRC) CSCs subpopulation.The aim of this work is the study of the mentioned embryonic marker in sensible andoxaliplatin-resistant (OXA) human CRC cancer lines, and in cultures derived of themenriched with CSC-like subpopulation, in order to detect novel markers associated toresistance in these cells. We characterized the expression of Oct-4, Nanog and Sox-2 byimmunofluorescence, cell cytometer and real time-PCR in sensible or resistant human CRCcell to oxaliplatin (T-84 and HCT-116) and in cultures enriched by CSC-likesubpopulation. The last cultures were obtained by growing tumor cells as colonospheres(CSPHE) in minimum medium in low adherence surfaces. On the other hand, we alsomeasured the reactive oxygen species (ROS) levels as a characteristic associated to CSC-like subpopulation. The expression of Nanog and Sox-2 was not changed in sensible andresistant cell lines grown in monolayer or as CSPH cultures. However, the expression ofOct-4 was positive in 6-12% and 40-50% of sensible cells that were grown in monolayer oras CSPHE respectively. About chemoresistant cells lines, 40-60% and 75-85% of cellswere positively for Oct-4 depending if cells were grown as monolayer or as CSPHErespectively. About ROS level, cells that were grown as CSPHE had shown significantlower levels in respect to cells that were grown as monolayer. These results showed thatOct-4 could be a promising marker to identify chemoresistant cells with CSC-likecharacteristics in CRC