@article{94dcfbc7a45f473eb30b69ab05f267ff,
title = "Anticancer sulfonamides target splicing by inducing RBM39 degradation via recruitment to DCAF15",
abstract = "Indisulam is an aryl sulfonamide drug with selective anticancer activity. Its mechanism of action and the basis for its selectivity have so far been unknown. Here we show that indisulam promotes the recruitment of RBM39 (RNA binding motif protein 39) to the CUL4-DCAF15 E3 ubiquitin ligase, leading to RBM39 polyubiquitination and proteasomal degradation. Mutations in RBM39 that prevent its recruitment to CUL4-DCAF15 increase RBM39 stability and confer resistance to indisulam's cytotoxicity. RBM39 associates with precursor messenger RNA (pre-mRNA) splicing factors, and inactivation of RBM39 by indisulam causes aberrant pre-mRNA splicing. Many cancer cell lines derived fromhematopoietic and lymphoid lineages are sensitive to indisulam, and their sensitivity correlates with DCAF15 expression levels. Two other clinically tested sulfonamides, tasisulam and chloroquinoxaline sulfonamide, share the same mechanism of action as indisulam. We propose that DCAF15 expression may be a useful biomarker to guide clinical trials of this class of drugs, which we refer to as SPLAMs (splicing inhibitor sulfonamides).",
author = "Ting Han and Maria Goralski and Nicholas Gaskill and Emanuela Capota and Jiwoong Kim and Ting, {Tabitha C.} and Yang Xie and Williams, {Noelle S.} and Deepak Nijhawan",
note = "Funding Information: We thank J. Ready, S. McKnight, and M. Brown for critically evaluating our manuscript. We thank S. Elledge for suggesting the use of MLN4924 as a tool compound, B. Kaelin for providing the His-tagged ubiquitin construct, and D. McFadden for providing a plasmid containing the TIR1 sequence. R. Tomaino and colleagues at the Harvard Medical School Taplin Mass Spectrometry Facility performed shotgun mass spectrometry on RBM39-bound proteins. We are grateful to J. McKnight, who provided assistance in cloning RBM39 repair templates; K. Klein for support with Sf9 cell culture; Z. Otwinowski, who confirmed the presence of RBM39 mutations through an independent analysis of whole-exome sequencing data; and U. Tambar and P. Le for synthesizing and providing indisulam. CQS (NSC 339004) was obtained from the National Cancer Institute (NCI), Division of Cancer Treatment and Diagnosis, Developmental Therapeutics Program. T.H. is a Howard Hughes Medical Institute Fellow of the Life Sciences Research Foundation. J.K. is supported by the Cancer Prevention and Research Institute of Texas (grant RP150596). D.N. is supported by a Harold C. Simmons Cancer Center Startup Award, a Disease-Oriented Clinical Scholar award, a Damon Runyon Clinical Investigator award (CI-68-13), and a grant from the Welch Foundation (I-1879). The University of Texas Southwestern Medical Center and the authors (D.N., T.H., and N.G.) have filed a patent application (U.S. Provisional Patent Application no. 62/425,732) related to the use of tasisulam, CQS, or indisulam in cancer patients whose tumors harbor mutations in splicing factors or express DCAF15. Exome-sequencing and RNAsequencing data from this study have been deposited at the National Center for Biotechnology Information Sequence Read Archive under accession numbers SRP068238 and SRP096666. T.H. designed the study, executed experiments, made the figures, and wrote the manuscript. M.G. performed the initial HCT-116 screen and the validation experiments. N.G. purified RBM39 complex, leading to the discovery of DCAF15 as the substrate receptor for RBM39 (Figs. 2D, 3E, and 4A). E.C. expressed and purified recombinant RBM39D150 protein. J.K. and Y.X. performed bioinformatics analyses of exome sequencing and RNA sequencing. T.C.T. expressed and purified DDB1-DCAF15 and performed gel filtration analysis of DDB1-DCAF15-RBM39 complex (fig. S9). N.S.W. performed the mouse xenograft experiment (Fig. 1H) and mass spectrometry quantification of indisulam (Fig. 4D). D.N. designed and supervised the study, performed correlation analysis of indisulam sensitivity with basal gene expression and copy number variation, and wrote the manuscript. Publisher Copyright: Copyright {\textcopyright} 2016 by the American Association for the Advancement of Science; all rights reserved.",
year = "2017",
month = apr,
day = "28",
doi = "10.1126/science.aal3755",
language = "English (US)",
volume = "356",
journal = "Science",
issn = "0036-8075",
publisher = "American Association for the Advancement of Science",
number = "6336",
}