Background: The present study was carried out to determine whether a quantitative relationship exists between the expressions of 3 cancer stem cell (CSC) markers and the degree of differentiation of gastric cancer.
Methods: The expressions of 3 putative CSC markers, ABCB1, ABCG2, and CD133, were detected in 90 human gastric adenocarcinoma cases by immunofluorescence assay. The differentiation statuses of 3 gastric cancer cell lines (the undifferentiated gastric cancer cell line HGC-27, the poorly differentiated gastric cancer cell line BGC-823, and the moderately-poorly differentiated gastric adenocarcinoma cell line SGC-7901) were observed and compared by performing the 3-[4,5-dimethylthiazol-2yl]-2,5-diphenyl tetrazolium bromide (MTT) assay. Gastric xenotransplant cancers in nude mice were constructed to compare the malignancy of the 3 variously differentiated gastric cancer cell lines. The expressions of the 3 putative CSC markers were also detected in the 3 gastric cancer cell lines in vitro by flow cytometric analysis and in the 3 gastric xenotransplant cancers in vivo by immunofluorescence staining.
Results: The expressions of ABCB1, ABCG2, and CD133 were generally correlated with the degree of differentiation of the gastric cancers. In the human gastric adenocarcinomas and in the cancer cell lines, the expressions of ABCB1, ABCG2, and CD133 increased with the increases in the malignancy grades of the gastric cancers. In the human gastric adenocarcinomas, poorly differentiated adenocarcinoma expressed more ABCB1, ABCG2, and CD133 than well-differentiated adenocarcinoma. In addition, the expressions of ABCB1 and CD133 were higher in the diffuse type than in the intestinal type of human gastric cancers. The undifferentiated cell line HGC-27 expressed more putative CSC markers than the moderately-poorly differentiated cell line SGC-7901. Similar results were observed in the xenotransplant tumors that arose from the 3 gastric cancer cell lines.
Conclusions: The expressions of the CSC markers ABCB1, ABCG2, and CD133 differed in the gastric cancers with various degrees of differentiation, with poorly differentiated gastric cancer expressing relatively more CSC markers.