Negative feedback-defective PRPS1 mutants drive thiopurine resistance in relapsed childhood ALL.

ABSTRACT: Relapse is the leading cause of mortality in children with acute lymphoblastic leukemia (ALL). Among chemotherapeutics, thiopurines are key drugs in ALL combination therapy. Using whole-exome sequencing, we identified relapse-specific mutations in the phosphoribosyl pyrophosphate synthetase 1 gene (PRPS1), which encodes a rate-limiting purine biosynthesis enzyme, in 24/358 (6.7%) relapsed childhood B cell ALL (B-ALL) cases. All individuals who harbored PRPS1 mutations relapsed early during treatment, and mutated ALL clones expanded exponentially before clinical relapse. Our functional analyses of PRPS1 mutants uncovered a new chemotherapy-resistance mechanism involving reduced feedback inhibition of de novo purine biosynthesis and competitive inhibition of thiopurine activation. Notably, t

SUBMITTER: Li B 

PROVIDER: S-EPMC4670083 | biostudies-literature | 2015 Jun

REPOSITORIES: biostudies-literature