ABSTRACT
Multi-drug resistance (MDR) is a phenomenon that tumor cells are exposed to a chemotherapeutic drug for a long time and then develop resistance to a variety of other anticancer drugs with different structures and different mechanisms. The in vitro studies of tumor cell lines cannot systematically reflect the role of MDR gene in vivo, and the cost of in vivo studies of transgenic mice as animal models is high. Given the myriad merits of zebrafish relative to other animal models, we aimed to establish a screening system using zebrafish stably expressing ATP-binding cassette (ATP-cassette) superfamily transporters and unveil the potential regulatory mechanism. We first used the Tol2-mediated approach to construct a Tg (abcb4:EGFP) transgenic zebrafish line with ATP-binding cassette (ABC) subfamily B member 4 (abcb4) gene promoter to drive EGFP expression. The expression levels of abcb4 and EGFP were significantly increased when Tg(abcb4:EGFP) transgenic zebrafish embryos were exposed to doxorubicin (DOX) or vincristine (VCR), and the increases were accompanied by a marked decreased accumulation of rhodamine B (RhB) in embryos, indicating a remarkable increase in DOX or VCR efflux. Mechanistically, Akt and Erk signalings were activated upon the treatment with DOX or VCR. With the application of Akt and Erk inhibitors, drug resistance was reversed with differing responsive effects. Notably, downstream NF-κB played a central role in the regulation of abcb4-mediated drug resistance. Taken together, the data indicate that the engineered Tg(abcb4:EGFP) transgenic zebrafish model is a new platform for screening drug resistance in vivo, which may facilitate and accelerate the process of drug development.
Subject(s)
ATP-Binding Cassette Transporters , NF-kappa B , Zebrafish Proteins , Zebrafish , ATP-Binding Cassette Transporters/genetics , ATP-Binding Cassette Transporters/metabolism , Animals , Animals, Genetically Modified , Cell Line, Tumor , Doxorubicin/pharmacology , Drug Resistance , Drug Resistance, Neoplasm , NF-kappa B/metabolism , Proto-Oncogene Proteins c-akt/metabolism , Vincristine/pharmacology , Zebrafish/genetics , Zebrafish/metabolism , Zebrafish Proteins/genetics , Zebrafish Proteins/metabolismABSTRACT
OBJECTIVE: To determine the effect of doxorubicin (DOX) on abcb4 gene expression and the role of abcb4 gene in multidrug-resistance. METHODS: Zebrafish embryos were treated with 2 mL/L DMSO, 10 µmol/L DOX and 2 mL/L DMSO+10 µmol/L DOX, respectively. The zebrafish embryos treated with Eggwater served as controls. Exposures started at 4 to 16 cell stage of the embryos and terminated 120 hours post fertilization (hpf). The expression of abcb4 gene in zebrafish embryos was examined on 48, 72, 96, and 120 hpf with whole-mount in situ hybridization (WISH) and quantitative real-time PCR (qPCR). RESULTS: Compared with the controls, DOX-exposed embryos had higher level of abcb4 gene expression (P < 0.05), but not for abcb5 gene. WISH showed that abcb4 gene was expressed in the guts of zebrafish embryos. However, those exposed to DOX also showed strong WISH signals in the brain and heart. CONCLUSION: Doxorubicin increases the expression of abcb4 gene in zebrafish embryos. abcb4 gene may play an imoortant role in multidrug-resistance.
