ABCG2 is required for self-renewal and chemoresistance of CD133-positive human colorectal cancer cells
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There is increasing evidence supporting the cancer stem cell (CSC) hypothesis, which suggests that a population of tumor cells with stem cell characteristics is responsible for tumor growth, resistance, and recurrence as well as drug resistance. In colorectal cancer, the CD133 antigen defines distinct cell subpopulations that are rich in tumor-initiating cells; however, the drug resistance properties of these CD133-positive cells have not been well defined. The breast cancer resistance protein (BCRP)/ATP-binding cassette subfamily G member 2 (ABCG2) is present on the plasma membrane of many types of human cancer cells and contributes to multidrug resistance during chemotherapy. The results of the present study showed that ABCG2 is expressed in CD133-positive CSCs from human colorectal tumors. Furthermore, the downregulation of ABCG2 expression inhibited the self-renewal capacity of these cells, and significantly enhanced the efficacy of chemotherapy-induced apoptosis in LS174T colon adenocarcinoma cells and CD133-positive colorectal carcinoma cells. Together, these data show that ABCG2 expression correlates with the presence of CD133-positive cancer cells, and thus is a possible therapeutic target for colorectal cancer.
KeywordsABCG2 CD133+ Chemoresistance Colorectal cancer cell Self-renewal
This work is supported by the China Natural Science Foundation (No. 81260309), Ningxia Province Science Research Foundation of China (No. 79), and the Ningxia Medical University Research Foundation of China (No. XM201135).
Compliance with ethical standards
Thirty-six primary tumor specimens were collected from tumors surgically removed from patients diagnosed to have colorectal cancers in the surgical center of the General Hospital of Ningxia Medical University, and according to the ethical standards of the institutional committee approved by Ningxia Medical University. Informed consent was obtained from all patients included in the study.
Conflicts of interest
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