Mutations at amino-acid 482 in the ABCG2 gene affect substrate and antagonist specificity
| Autor: | T A Nadjem, Yasumasa Honjo, Marianne S. Poruchynsky, M Risbood, S Runge, Kuniaki Morisaki, Robert W. Robey, Susan E. Bates |
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| Rok vydání: | 2003 |
| Předmět: |
Cancer Research
animal structures BCRP/MXR/ABCP/ABCG2 Daunorubicin Blotting Western Mutant Cell Culture Techniques Antineoplastic Agents ATP-binding cassette transporter Biology Kidney Transfection medicine.disease_cause Rhodamine 123 mitoxantrone Substrate Specificity chemistry.chemical_compound drug-resistance medicine ATP Binding Cassette Transporter Subfamily G Member 2 Humans Point Mutation Depsipeptide Mutation flow cytometry Wild type Genetics and Genomics Drug Resistance Multiple Neoplasm Proteins Gene Expression Regulation Neoplastic Oncology chemistry Biochemistry embryonic structures ATP-Binding Cassette Transporters sense organs mutation medicine.drug |
| Zdroj: | British Journal of Cancer |
| ISSN: | 1532-1827 0007-0920 |
| Popis: | Recent studies have shown that mutations at amino-acid 482 in the ABCG2 gene affect the substrate specificity of the protein. To delineate the effects of these mutations clearly, human embryonic kidney cells (HEK-293) were stably transfected with wild-type 482R or mutant 482G and 482T ABCG2. By flow cytometry, mitoxantrone, BODIPY-prazosin, and Hoechst 33342 were found to be substrates of all ABCG2 proteins, while rhodamine 123, daunorubicin, and LysoTracker Green were transported only by mutant ABCG2. In cytotoxicity assays, all ABCG2 proteins conferred high levels of resistance to mitoxantrone, SN-38, and topotecan, while mutant ABCG2 also exhibited a gain of function for mitoxantrone as they conferred a four-fold greater resistance compared to wild type. Cells transfected with mutant ABCG2 were 13- to 71- fold resistant to the P-glycoprotein substrates doxorubicin, daunorubicin, epirubicin, bisantrene, and rhodamine 123 compared to cells transfected with wild-type ABCG2, which were only three- to four-fold resistant to these compounds. ABCG2 did not confer appreciable resistance to etoposide, taxol or the histone deacetylase inhibitor depsipeptide. None of the transfected cell lines demonstrated resistance to flavopiridol despite our previous observation that ABCG2-overexpressing cell lines are cross-resistant to the drug. Recently reported inhibitors of ABCG2 were evaluated and 50 microM novobiocin was found to reverse wild-type ABCG2 completely, but only reverse mutant ABCG2 partially. The studies presented here serve to underscore the importance of amino-acid 482 in defining the substrate specificity of the ABCG2 protein and raise the possibility that amino-acid 482 mutations in human cancers could affect the clinical application of antagonists for ABCG2. |
| Databáze: | OpenAIRE |
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