CRISPR Screening Identifies WEE1 as a Combination Target for Standard Chemotherapy in Malignant Pleural Mesothelioma

Our plain-English summary of CRISPR Screening Identifies WEE1 as a Combination Target for Standard Chemotherapy in Malignant Pleural Mesothelioma, by D. Xu, S.Q. Liang, H. Yang, et al (Molecular Cancer Therapeutics, 2020).

The study

• Authors: D. Xu, S.Q. Liang, H. Yang, R. Bruggmann, S. Berezowska, Z. Yang, T.M. Marti, S.R.R. Hall, Y. Gao, G.J. Kocher, R.A. Schmid, R.W. Peng
• Journal: Molecular Cancer Therapeutics
• Published: 2020;19(2):661-672
• Type of article: Case report
• Cited by: 30 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Malignant pleural mesothelioma (MPM) is an aggressive cancer with dismal prognosis, largely due to poor response rates to and rapid relapse after first-line pemetrexed (MTA)/cisplatin chemotherapy. A better understanding of the molecular mechanisms underlying chemotherapy sensitivity and duration represents a significant but still unmet clinical need. In this study, we reported on a kinome CRISPR/Cas9 knockout screen that identified several G2-M checkpoint kinases, including WEE1, whose loss of function sensitizes MPM cells to standard chemotherapy. We further showed that deregulation of the G2-M checkpoint contributes to chemotherapy resistance, and that WEE1 inhibition synergizes with cisplatin/MTA, leading to enhanced MPM cell death in vitro and potent antitumor effects in vivo Mechanistically, WEE1 blockage overrides chemotherapy-induced G2-M cell-cycle arrest and promotes premature mitotic entry, which causes DNA damage accumulation and ultimately apoptosis. Our results suggest a new therapeutic combination for MPM, and support the application of CRISPR/Cas9-based functional genomics in identifying novel therapeutic targets to potentiate existing cancer therapies.

©2019 American Association for Cancer Research.

In plain English

This laboratory study of malignant pleural mesothelioma (MPM) used cell lines, cells from one patient's tumor, and mice with implanted tumors. No patients were treated, and asbestos exposure was not studied. Using CRISPR gene editing, the authors switched off 763 kinase genes in MESO-1 cells given standard chemotherapy, cisplatin plus pemetrexed (MTA). Of 33 kinase hits, six, including WEE1, met their follow-up criteria. WEE1-knockout cells were markedly more sensitive to chemotherapy. The WEE1-blocking drug AZD1775 combined with chemotherapy showed synergy in five cell lines and the patient-derived cells, and resensitized three chemotherapy-resistant lines. In mice with MESO-1 tumors, average tumor weight after 21 days was 50.7 mg (plus or minus 8 mg) with combined treatment and 162.4 mg (plus or minus 51 mg) with control treatment. With tumors from the patient's cells, average tumor weights after 4 weeks were 69.9 mg (plus or minus 30 mg) with combined treatment and 302.8 mg (plus or minus 118 mg) with control treatment. The authors concluded that their results provide strong mechanistic evidence for combining WEE1 inhibitors with standard chemotherapy to treat MPM.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory (preclinical) study: a CRISPR/Cas9 kinase-gene knockout screen in MPM cell lines, followed by cell experiments and mouse xenograft experiments
• Who was studied: MPM cell lines (H28, MESO-1, MESO-4, MSTO-211H, JL-1), chemotherapy-resistant versions of three of them, a primary culture (BE261T) from the tumor of a 67-year-old man treated after neoadjuvant chemotherapy, and NSG mice carrying implanted MESO-1 or BE261T tumors (Bern, Switzerland)
• Exposure: No asbestos exposure was studied. The treatments tested were cisplatin plus pemetrexed chemotherapy, WEE1 gene knockout, and the WEE1 inhibitor AZD1775. In mice: cisplatin 3.75 mg/kg plus pemetrexed 83 mg/kg once weekly, and AZD1775 30 mg/kg once daily, for 3 to 4 weeks.
• Main results:
  • In the screen of MESO-1 cells treated with chemotherapy, 33 kinase hits were identified. Six (WEE1, AURKA, MPP3, MAP3K12, DGKD and SPEG) met the criteria for follow-up.
  • MESO-1 cells with WEE1 knocked out were markedly more sensitive to cisplatin/MTA than control cells.
  • AZD1775 and cisplatin/MTA acted synergistically in MESO-1 cells and also in the MSTO-211H, H28, MESO-4 and JL-1 cell lines.
  • In the patient-derived BE261T cells, the combination of AZD1775 and chemotherapy produced strong synergy.
  • In MESO-1 cells, the combination of AZD1775 and chemotherapy increased a marker of DNA damage compared with either treatment alone.
  • In public drug-sensitivity data, no correlation was seen between p53 status and sensitivity to a WEE1 inhibitor in MPM cell lines.
  • Chemotherapy-resistant cell lines showed stronger activation of the G2–M checkpoint. AZD1775 restored their sensitivity to cisplatin/MTA.
  • In mice with MESO-1 tumors, average tumor weights after 21 days were 162.4 plus or minus 51 mg (control), 102.9 plus or minus 21 mg (cisplatin/MTA), 143.8 plus or minus 26 mg (AZD1775) and 50.7 plus or minus 8 mg (combination). The authors reported this as about 36.6% (cisplatin/MTA), 11.4% (AZD1775) and 68.7% (combination) shrinkage relative to control.
  • In mice with tumors derived from the patient's cells (BE261T), average tumor weights after 4 weeks were 302.8 plus or minus 118 mg (control), 165.7 plus or minus 23 mg (cisplatin/MTA), 268.8 plus or minus 68 mg (AZD1775) and 69.9 plus or minus 30 mg (combination).
• The authors' conclusion: The authors concluded that their results provide strong mechanistic evidence for combining WEE1 inhibitors with standard chemotherapy to treat MPM.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Chemotherapy, Pleural Mesothelioma, Prognosis, Pemetrexed (Alimta), Cisplatin, Apoptosis.

Related studies

• Abrogating G₂/M checkpoint through WEE1 inhibition in combination with chemotherapy as a promising therapeutic approach for mesothelioma — P. Indovina, E. Marcelli, et al. (2014)
• Pharmacological Inhibition of WEE1 Potentiates the Antitumoral Effect of the dl922-947 Oncolytic Virus in Malignant Mesothelioma Cell Lines — C.A. Iannuzzi, P. Indovina, et al. (2020)
• Not so WEE: targeting G₂/M to kill mesothelioma cells — P. Dent (2014)
• Increased sensitivity to apoptosis upon endoplasmic reticulum stress-induced activation of the unfolded protein response in chemotherapy-resistant malignant pleural mesothelioma — D. Xu, S.Q. Liang, et al. (2018)
• Comprehensive Testing of Chemotherapy and Immune Checkpoint Blockade in Preclinical Cancer Models Identifies Additive Combinations — N. Principe, W.J. Aston, et al. (2022)
• An RNAi-based screen reveals PLK1, CDK1 and NDC80 as potential therapeutic targets in malignant pleural mesothelioma — A. Linton, Y.Y. Cheng, et al. (2014)

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