Mutations in adenosine deaminase-like (ADAL) protein confer resistance to the antiproliferative agents N6-cyclopropyl-PMEDAP and GS-9219.

BACKGROUND/AIM:GS 9219 is a double prodrug of antiproliferative nucleotide analog 9-(2-Phosphonylmethoxyethyl)guanine (PMEG), with potent in vivo efficacy against various hematological malignancies. This study investigates the role of adenosine deaminase-like (ADAL) protein in the intracellular activation of GS-9219. MATERIALS AND METHODS:A cell line resistant to 9-(2-Phosphonylmethoxyethyl)-N(6)-cyclopropyl-2,6-diaminopurine (cPrPMEDAP), an intermediate metabolite of GS-9219, was generated and characterized. RESULTS:The resistant cell line was cross-resistant to cPrPMEDAP and GS-9219, due to a defect in the deamination of cPrPMEDAP to PMEG. Mutations in the ADAL gene (H286R and S180N) were identified in the resistant cells that adversely-affected its enzymatic activity. Introduction of the wild-type ADAL gene re-sensitized resistant cells to both cPrPMEDAP and GS-9219. CONCLUSION:The ADAL protein plays an essential role in the intracellular activation of GS-9219 by catalyzing the deamination of cPrPMEDAP metabolite to PMEG. Mutations affecting the activity of ADAL confer resistance to both GS-9219 and its metabolite cPrPMEDAP.

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