Abstract 4370: Genome-wide CRISPR-Cas9 screens reveal loss of redundancy between PKMYT1 and WEE1 in patient-derived glioblastoma stem-like cells

• Published in: Cancer research (Chicago, Ill.) Ill.), 2016-07, Vol.76 (14_Supplement), p.4370-4370
• Main Authors: Toledo, Chad, Yu, Ding, Hoellerbauer, Pia, Davis, Ryan, Basom, Ryan, Girard, Emily, Corrin, Philip, Bolouri, Hamid, Davison, Jerry, Zhang, Qing, Nam, Do-Hyun, Lee, Jeongwu, Pollard, Steven, Delrow, Jeffery, Clurman, Bruce, Olson, James, Paddison, Patrick
• Format: Article
• Language: English
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.AM2016-4370

Glioblastoma multiforme (GBM) is the most aggressive and common form of brain cancer in adults. There are currently no effective therapies for GBM. Even with standard of care treatments, such as surgery, radiation, and chemotherapy, ∼90% of adult patients die within 2 years of diagnosis. To identify therapeutic targets for Glioblastoma (GBM), we performed genome-wide CRISPR-Cas9 “knockout” (KO) screens in patient-derived GBM stem-like cells (GSCs) and human neural stem/progenitors (NSCs), non-neoplastic stem cell controls, for genes required for their in vitro growth. Surprisingly, the vast majority GSC-lethal hits were found outside of molecular networks commonly altered in GBM and GSCs (e.g., oncogenic drivers). In vitro and in vivo validation of GSC-specific targets revealed several strong hits, including the wee1-like kinase, PKMYT1/Myt1. Mechanistic studies demonstrated that PKMYT1 acts redundantly with WEE1 to inhibit Cyclin B-CDK1 activity via CDK1-Y15 phosphorylation and to promote timely completion of mitosis in NSCs. However, in GSCs, this redundancy is lost, likely as a result of oncogenic signaling, causing GBM-specific lethality. From a biological standpoint, our results help re-discover PKMYT1 function in human cells. From a cancer standpoint, these results suggest that targeting PKMYT1 is a glioma-lethal gene and that tandem or sequential use of PKMYT1 and WEE1 inhibitors may illicit therapeutic responses in GBM. In addition to these results we will also present retest data for other candidate glioma-lethal genes and networks in multiple patient samples. Citation Format: Chad Toledo, Ding Yu, Pia Hoellerbauer, Ryan Davis, Ryan Basom, Emily Girard, Philip Corrin, Hamid Bolouri, Jerry Davison, Qing Zhang, Do-Hyun Nam, Jeongwu Lee, Steven Pollard, Jeffery Delrow, Bruce Clurman, James Olson, Patrick Paddison. Genome-wide CRISPR-Cas9 screens reveal loss of redundancy between PKMYT1 and WEE1 in patient-derived glioblastoma stem-like cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4370.