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NUDT15 polymorphism and NT5C2 and PRPS1 mutations influence thiopurine sensitivity in acute lymphoblastic leukaemia cells |
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| Authors: | Shinpei Somazu Yoichi Tanaka Minori Tamai Atsushi Watanabe Keiko Kagami Masako Abe Daisuke Harama Tamao Shinohara Koshi Akahane Kumiko Goi Kanji Sugita Takaya Moriyama Jun Yang Hiroaki Goto Masayoshi Minegishi Shotaro Iwamoto Junko Takita Takeshi Inukai |
| Institution: | 1. Department of Pediatrics, University of Yamanashi, Yamanashi, Japan;2. Department of Clinical Pharmacy, Center for Clinical Pharmacy and Sciences, School of Pharmacy, Kitasato University, Minato-ku, Japan
Contribution: Data curation (equal), Formal analysis (equal), Funding acquisition (equal), Investigation (equal), Methodology (equal), Visualization (equal), Writing - original draft (equal), Writing - review & editing (equal);3. Department of Pediatrics, University of Yamanashi, Yamanashi, Japan Contribution: Formal analysis (equal), Writing - review & editing (equal);4. Department of Pediatrics, University of Yamanashi, Yamanashi, Japan Contribution: Data curation (equal), Formal analysis (equal), Writing - review & editing (equal);5. Department of Pediatrics, University of Yamanashi, Yamanashi, Japan Contribution: Resources (equal), Supervision (equal), Writing - review & editing (equal);6. Department of Pharmaceutical Sciences, St Jude Children's Research Hospital, Memphis, Tennessee, USA Contribution: Conceptualization (equal), Methodology (equal), Writing - review & editing (equal);7. Division of Hematology/Oncology, Kanagawa Children's Medical Center, Kanagawa, Japan Contribution: Resources (equal), Writing - review & editing (equal);8. Tohoku Block Center, Japanese Red Cross Society, Sendai, Japan Contribution: Resources (equal), Writing - review & editing (equal);9. Department of Pediatrics, Mie University Graduate School of Medicine, Tsu, Japan Contribution: Resources (equal), Writing - review & editing (equal);10. Department of Pediatrics, Kyoto University, Kyoto, Japan Contribution: Resources (equal), Writing - review & editing (equal) |
| Abstract: | In chemotherapy for childhood acute lymphoblastic leukaemia (ALL), maintenance therapy consisting of oral daily mercaptopurine and weekly methotrexate is important. NUDT15 variant genotype is reportedly highly associated with severe myelosuppression during maintenance therapy, particularly in Asian and Hispanic populations. It has also been demonstrated that acquired somatic mutations of the NT5C2 and PRPS1 genes, which are involved in thiopurine metabolism, are detectable in a portion of relapsed childhood ALL. To directly confirm the significance of the NUDT15 variant genotype and NT5C2 and PRPS1 mutations in thiopurine sensitivity of leukaemia cells in the intrinsic genes, we investigated 84 B-cell precursor-ALL (BCP-ALL) cell lines. Three and 14 cell lines had homozygous and heterozygous variant diplotypes of the NUDT15 gene, respectively, while 4 and 2 cell lines that were exclusively established from the samples at relapse had the NT5C2 and PRPS1 mutations, respectively. Both NUDT15 variant genotype and NT5C2 and PRPS1 mutations were significantly associated with DNA-incorporated thioguanine levels after exposure to thioguanine at therapeutic concentration. Considering the continuous exposure during the maintenance therapy, we evaluated in vitro mercaptopurine sensitivity after 7-day exposure. Mercaptopurine concentrations lethal to 50% of the leukaemia cells were comparable to therapeutic serum concentration of mercaptopurine. Both NUDT15 variant genotype and NT5C2 and PRPS1 mutations were significantly associated with mercaptopurine sensitivity in 83 BCP-ALL and 23 T-ALL cell lines. The present study provides direct evidence to support the general principle showing that both inherited genotype and somatically acquired mutation are crucially implicated in the drug sensitivity of leukaemia cells. |
| Keywords: | acute lymphoblastic leukemia maintenance therapy mercaputopurine pharmacogenetics |