Transposon Mutagenesis Reveals Fludarabine Resistance Mechanisms in Chronic Lymphocytic Leukemia.

Abstract

PURPOSE To identify resistance mechanisms for the chemotherapeutic drug fludarabine in chronic lymphocytic leukemia (CLL), as innate and acquired resistance to fludarabine-based chemotherapy represents a major challenge for long-term disease control. EXPERIMENTAL DESIGN We used piggyBac transposon-mediated mutagenesis, combined with next-generation sequencing, to identify genes that confer resistance to fludarabine in a human CLL cell line. RESULTS In total, this screen identified 782 genes with transposon integrations in fludarabine-resistant pools of cells. One of the identified genes is a known resistance mediator DCK (deoxycytidine kinase), which encodes an enzyme that is essential for the phosphorylation of the prodrug to the active metabolite. BMP2K, a gene not previously linked to CLL, was also identified as a modulator of response to fludarabine. In addition, 10 of 782 transposon-targeted genes had previously been implicated in treatment resistance based on somatic mutations seen in patients refractory to fludarabine-based therapy. Functional characterization of these genes supported a significant role for ARID5B and BRAF in fludarabine sensitivity. Finally, pathway analysis of transposon-targeted genes and RNA-seq profiling of fludarabine-resistant cells suggested deregulated MAPK signaling as involved in mediating drug resistance in CLL. CONCLUSIONS To our knowledge, this is the first forward genetic screen for chemotherapy resistance in CLL. The screen pinpointed novel genes and pathways involved in fludarabine resistance along with previously known resistance mechanisms. Transposon screens can therefore aid interpretation of cancer genome sequencing data in the identification of genes modifying sensitivity to chemotherapy. Clin Cancer Res; 22(24); 6217-27. ©2016 AACR.

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@article{Pandzic2016TransposonMR, title={Transposon Mutagenesis Reveals Fludarabine Resistance Mechanisms in Chronic Lymphocytic Leukemia.}, author={Tatjana Pandzic and Jimmy Larsson and Liqun He and Snehangshu Kundu and Kenneth H K Ban and Muhammad Akhtar-Ali and Anders R. Hellstr{\"{o}m and Anna Schuh and Ruth Clifford and S Blakemore and Jonathan C. Strefford and Tycho Baumann and Armando L{\'o}pez-Guillermo and El{\'i}as Campo and Viktor Ljungstr{\"{o}m and Larry Mansouri and Richard Rosenquist and Tobias Sj{\"{o}blom and Mats Hellstr{\"{o}m}, journal={Clinical cancer research : an official journal of the American Association for Cancer Research}, year={2016}, volume={22 24}, pages={6217-6227} }