title: Afatinib enhances the efficacy of conventional chemotherapeutic agents by eradicating cancer stem-like cells.
abstract: Cancer stem cells (CSC) have garnered significant attention as a therapeutic focus, based on evidence that they may represent an etiologic root of treatment-resistant cells. Indeed, expression of the multidrug resistance protein ATP-binding cassette subfamily G member 2 (ABCG2) confers chemoresistance to CSCs, where it serves as a potential biomarker and therapeutic target. Here, we show that afatinib, a small-molecule inhibitor of the tyrosine kinases EGFR, HER2, and HER4, preferentially eliminated side population cells with CSC character, in both cell lines and patient-derived leukemia cells, by decreasing ABCG2 expression. In these cells, afatinib also acted in parallel to suppress self-renewal capacity and tumorigenicity. Combining afatinib with the DNA-damaging drug topotecan enhanced the antitumor effect of topotecan in vitro and in vivo. Mechanistic investigations suggested that ABCG2 suppression by afatinib did not proceed by proteolysis through the ubiquitin-dependent proteosome, lysosome, or calpain. Instead, we found that afatinib increased DNA methyltransferase activity, thereby leading to methylation of the ABCG2 promoter and to a decrease in ABCG2 message level. Taken together, our results advocate the use of afatinib in combination with conventional chemotherapeutic drugs to improve efficacy by improving CSC eradication.
authors: State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-sen University, Guangzhou, China. Collaborative Innovation Center for Cancer Medicine, Cancer Center, Guangzhou Sun Yat-sen University, Guangzhou, China.
authors: Xiao-kun
authors: XK
authors: Wang
authors: State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-sen University, Guangzhou, China. Collaborative Innovation Center for Cancer Medicine, Cancer Center, Guangzhou Sun Yat-sen University, Guangzhou, China.
authors: Jie-hua
authors: JH
authors: He
authors: First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
authors: Jing-hong
authors: JH
authors: Xu
authors: First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
authors: Sheng
authors: S
authors: Ye
authors: State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-sen University, Guangzhou, China. Collaborative Innovation Center for Cancer Medicine, Cancer Center, Guangzhou Sun Yat-sen University, Guangzhou, China.
authors: Fang
authors: F
authors: Wang
authors: State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-sen University, Guangzhou, China. Collaborative Innovation Center for Cancer Medicine, Cancer Center, Guangzhou Sun Yat-sen University, Guangzhou, China.
authors: Hui
authors: H
authors: Zhang
authors: State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-sen University, Guangzhou, China. Collaborative Innovation Center for Cancer Medicine, Cancer Center, Guangzhou Sun Yat-sen University, Guangzhou, China.
authors: Zhen-cong
authors: ZC
authors: Huang
authors: School of Pharmacy, The Chinese University of Hong Kong, Hong Kong, PR China.
authors: Kenneth Kin Wah
authors: KK
authors: To
authors: State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-sen University, Guangzhou, China. Collaborative Innovation Center for Cancer Medicine, Cancer Center, Guangzhou Sun Yat-sen University, Guangzhou, China. Fulw@mail.sysu.edu.cn.
authors: Li-wu
authors: LW
authors: Fu
mesh_terms: D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D000077716:Afatinib; D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D045744:Cell Line, Tumor; D019175:DNA Methylation; D004357:Drug Synergism; D006801:Humans; D007938:Leukemia / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D061986:MCF-7 Cells; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D014411:Neoplastic Stem Cells / Q000187:drug effects* / Q000473:pathology; D011401:Promoter Regions, Genetic; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011799:Quinazolines / Q000008:administration & dosage / Q000494:pharmacology*; D011897:Random Allocation; D015398:Signal Transduction; D019772:Topotecan / Q000008:administration & dosage / Q000494:pharmacology; D023041:Xenograft Model Antitumor Assays
chemical_list: C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D009363:Neoplasm Proteins; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D000077716:Afatinib; D019772:Topotecan