Objective:To investigate the influence of CD133+expression on patients’survival and resistance of CD133+cells to anti-tumor agents in gastric cancer(GC).Methods:Influence of CD133 expression on prognosis was analyzed employing samples from patients with GC.GC cell lines were utilized to separate CD133+and CD133-subpopulations by immunomagnetic separation and to analyze the biological features of two subpopulations in vitro and in vivo,especially in resistant to anti-tumor reagents and its apoptotic mechanism.Results:The lower CD133+group showed a significantly better survival compared with the higher CD133+group.The highest content of CD133+subpopulations for KATO-III cells had stronger proliferative ability than CD133-subpopulations.A single CD133+cell was capable of generating new cell colony and the tumorigenicity rate in nude mice was100%for CD133+clonal spheres or for CD133+cells,but 0%for CD133-cells.Furthermore,the higher expression levels of Oct-4,Sox-2,Musashi-1 and ABCG2 in CD133+clonal spheres were identified compared with CD133+cells or CD133-cells.Under the treatment of anti-tumor reagents,CD133+cells had lower suppression rates compared with CD133-cells while lower level of Bcl-2 and higher level of Bax were found in CD133+cells compared with CD133-cells.Conclusions:The patients with lower CD133+expression had a better survival.Enriched CD133+cells in clonal sphere shared the ability to be self-renewable,proliferative,tumorigenic and resistant to anti-tumor agents as probably regulated by Bcl-2 and Bax. Objective: To investigate the influence of CD133 + expression on patients’ survival and resistance of CD133 + cells to anti-tumor agents in gastric cancer (GC). Methods: Influence of CD133 expression on prognosis was analyzed employing samples from patients with GC. GC cell lines were utilized to separate CD133 + and CD133-subpopulations by immunomagnetic separation and to analyze the biological features of two subpopulations in vitro and in vivo, especially in resistant to anti-tumor reagents and its apoptotic mechanism. Results: The lower CD133 + group showed a significantly better survival compared with the higher CD133 + group. highest content of CD133 + subpopulations for KATO-III cells had stronger proliferative ability than CD133-subpopulations. A single CD133 + cell was capable of generating new cell colony and the tumorigenicity rate in nude mice was 100% for CD133 + clonal spheres or for CD133 + cells, but 0% for CD133-cells. More Next, the higher expression levels of Oct- 4, Sox- 2, Musashi- 1 and ABCG2 in C D133 + clonal spheres were identified compared with CD133 + cells or CD133-cells. Under the treatment of anti-tumor reagents, CD133 + cells had lower suppression rates compared with CD133-cells while lower level of Bcl-2 and higher level of Bax were found in CD133 + cells compared with CD133-cells. Conclusions: The patients with lower CD133 + expression had a better survival. Enriched CD133 + cells in clonal sphere shared the ability to be self-renewable, proliferative, tumorigenic and resistant to anti-tumor agents as probably regulated by Bcl-2 and Bax.