A Genome-wide CRISPR Screen Identifies CDC25A as a Determinant of Sensitivity to ATR Inhibitors

Abstract

One recurring theme in drug development is to exploit synthetic lethal properties as means to preferentially damage the DNA of cancer cells. We and others have previously developed inhibitors of the ATR kinase, shown to be particularly genotoxic for cells expressing certain oncogenes. In contrast, the mechanisms of resistance to ATR inhibitors remain unexplored. We report here on a genome-wide CRISPR-Cas9 screen that identified CDC25A as a major determinant of sensitivity to ATR inhibition. CDC25A-deficient cells resist high doses of ATR inhibitors, which we show is due to their failure to prematurely enter mitosis in response to the drugs. Forcing mitotic entry with WEE1 inhibitors restores the toxicity of ATR inhibitors in CDC25A-deficient cells. With ATR inhibitors now entering the clinic, our work provides a better understanding of the mechanisms by which these compounds kill cells and reveals genetic interactions that could be used for their rational use.

CRISPR-Cas9 screen reveals a MYCN-amplified neuroblastoma dependency on EZH2

“…Over the last 3 years, CRISPR-Cas9 has been applied to mammalian screens, including screens to identify mechanisms of resistance or enhanced sensitivity to drugs (9,13), to identify mediators of immune response (14), and to identify enhancer elements (15). To date, however, this approach has not been systematically Pharmacologically difficult targets, such as MYC transcription factors, represent a major challenge in cancer therapy.…”

Targeting the kinase activities of ATR and ATM exhibits antitumoral activity in mouse models of MLL -rearranged AML

“…Likewise, the toxicity of chemical inhibitors of ATR is higher in cells lacking p53 (10, 15, 16). This p53-independent cell killing by ATR inhibitors is linked to their capacity to induce the accumulation of DNA replication stress and premature mitotic entry, activities that are unrelated to p53 functions (17, 18). Hence, ATR inhibitors offer an alternative for the elimination of p53-deficient tumors.…”

Clasp2 ensures mitotic fidelity and prevents differentiation of epidermal keratinocytes

“…p53 knockout mouse keratinocytes were generated by infecting mouse keratinocytes (Drosten et al, 2014) with lentiCas9-Blast (gift from Feng Zhang, Massachusetts Institute of Technology, Cambridge, MA) and a pKLV-U6gRNA-PGKpuro2ABFP vector expressing p53sgRNA [gift from Sergio Ruiz, Spanish National Cancer Research Centre (CNIO, Madrid, Spain) (Ruiz et al, 2016) and maintained in CNT-07 (CELLnTEC, Bern, Switzerland).…”