April 27, 2019 | Jola Glotzer
In search of treatments for aggressive lymphomas
CBC Postdoctoral Research Award recipient Mark Manzano, and mentor, Eva Gottwein, NU, publish results of a screen designed to identify the mechanisms of drug resistance in primary effusion lymphoma (PEL)
Congratulations to Eva Gottwein and Mark Manzano, NU, for their recent publication in bioRxiv, titled “Genome-wide CRISPR Screens Reveal Genetic Mediators of Cereblon Modulator Toxicity in Primary Effusion Lymphoma.” The publication was partially funded by a CBC Postdoctoral Research Award to Manzano (2015, renewed for 2016). The team has devised a CRISPR/Cas9 screen to look for influencers of cereblon modulating agents (CMs) — a class of molecules that display varied levels of therapeutic activity against PEL. The authors identify several factors likely involved in acquiring drug resistance to CMs. They also provide new insights into developing biomarkers for the resistance to chemotherapy in PEL.
Publication attributed to CBC funding*:
Patil A, Manzano M, Gottwein E. Genome-wide CRISPR Screens Reveal Genetic Mediators of Cereblon Modulator Toxicity in Primary Effusion Lymphoma. bioRxiv preprint first posted online Apr. 25, 2019. (www.biorxiv.org)
Genome-wide CRISPR/Cas9 screens represent a powerful approach to study mechanisms of drug action and resistance. Cereblon modulating agents (CMs) have recently emerged as candidates for therapeutic intervention in primary effusion lymphoma (PEL), a highly aggressive cancer caused by Kaposi’s sarcoma-associated herpesvirus. CMs bind to cereblon (CRBN), the substrate receptor of the cullin-RING type E3 ubiquitin ligase CRL4CRBN, and thereby trigger the acquisition and proteasomal degradation of neosubstrates. Downstream mechanisms of CM toxicity are incompletely understood, however. To identify novel CM effectors and mechanisms of CM resistance, we performed positive selection CRISPR screens using three CMs with increasing toxicity in PEL: lenalidomide (LEN), pomalidomide (POM), and CC-122. Results identified several novel modulators of the activity of CRL4CRBN. The number of genes whose inactivation confers resistance decreases with increasing CM efficacy. Only inactivation of CRBN conferred complete resistance to CC-122. Inactivation of the E2 ubiquitin conjugating enzyme UBE2G1 also conferred robust resistance against LEN and POM. Inactivation of additional genes, including the Nedd8-specific protease SENP8, conferred resistance to only LEN. SENP8 inactivation indirectly increased levels of unneddylated CUL4A/B, which limits CRL4CRBN activity in a dominant negative manner. Accordingly, sensitivity of SENP8-inactivated cells to LEN is restored by overexpression of CRBN. In sum, our screens identify several novel players in CRL4CRBN function and define pathways to CM resistance in PEL. These results provide rationale for increasing CM efficacy upon patient relapse from a less efficient CM. Identified genes could finally be developed as biomarkers to predict CM efficacy in PEL and other cancers.
The authors thank the Northwestern University NUSeq Core Facility and the University of Chicago Genomics Facility for their Illumina sequencing services and Kylee Morrison and Samuel Harvey for their feedback on this manuscript. This study was supported by National Institutes of Health, National Cancer Institute Grant R21 CA210904, by Searle and Zell Scholar Awards from the Robert H. Lurie Comprehensive Cancer Center (E.G.), and by Chicago Biomedical Consortium Postdoctoral Award PDR-061 (M.M.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the funding agencies.
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October 17, 2018
▸ Rare disease and old drugs
CBC Postdoctoral Research Award contributes to a new Nature Communications publication by Mark Manzano and Eva Gottwein, NU