Pharmacological Inhibition of WEE1 Potentiates the Antitumoral Effect of the dl922-947 Oncolytic Virus in Malignant Mesothelioma Cell Lines

Our plain-English summary of Pharmacological Inhibition of WEE1 Potentiates the Antitumoral Effect of the dl922-947 Oncolytic Virus in Malignant Mesothelioma Cell Lines, by C.A. Iannuzzi, P. Indovina, I.M. Forte, et al (International Journal of Molecular Sciences, 2020).

The study

• Authors: C.A. Iannuzzi, P. Indovina, I.M. Forte, S. Di Somma, A.M. Malfitano, M. Bruno, G. Portella, F. Pentimalli, A. Giordano
• Journal: International Journal of Molecular Sciences
• Published: 2020;21(19)
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Malignant mesothelioma (MM) is a very aggressive asbestos-related cancer, for which no therapy proves to be effective. We have recently shown that the oncolytic adenovirus dl922-947 had antitumor effects in MM cell lines and murine xenografts. Previous studies demonstrated that dl922-947-induced host cell cycle checkpoint deregulation and consequent DNA lesions associated with the virus efficacy. However, the cellular DNA damage response (DDR) can counteract this virus action. Therefore, we assessed whether AZD1775, an inhibitor of the G2/M DNA damage checkpoint kinase WEE1, could enhance MM cell sensitivity to dl922-947. Through cell viability assays, we found that AZD1775 synergized with dl922-947 selectively in MM cell lines and increased dl922-947-induced cell death, which showed hallmarks of apoptosis (annexinV-positivity, caspase-dependency, BCL-XL decrease, chromatin condensation). Predictably, dl922-947 and/or AZD1775 activated the DDR, as indicated by increased levels of three main DDR players: phosphorylated histone H2AX (γ-H2AX), phospho-replication protein A (RPA)32, phospho-checkpoint kinase 1 (CHK1). Dl922-947 also increased inactive Tyr-15-phosphorylated cyclin-dependent kinase 1 (CDK1), a key WEE1 substrate, which is indicative of G2/M checkpoint activation. This increase in phospho-CDK1 was effectively suppressed by AZD1775, thus suggesting that this compound could, indeed, abrogate the dl922-947-induced DNA damage checkpoint in MM cells. Overall, our data suggest that the dl922-947-AZD1775 combination could be a feasible strategy against MM.

In plain English

This was a laboratory study in cultured cells testing whether the WEE1 inhibitor AZD1775 (MK-1775, adavosertib) increases the effect of the oncolytic adenovirus dl922-947 on malignant mesothelioma, an asbestos-related cancer. Two mesothelioma cell lines (NCI-H28 and MSTO-211H) were treated with each agent alone and in combination, while the normal mesothelial line MET-5A was treated with the combination at approximately the IC50 values identified in tumor cells. Cell viability assays followed by isobologram analysis showed synergism between AZD1775 and dl922-947 in both mesothelioma cell lines, with combination index values below 1; in MET-5A cells the combination produced only a slight, not significant toxicity after 5 days. The combination increased annexinV positivity above dl922-947 alone, and dl922-947 alone or combined produced cleaved caspase-3, reduced BCL-XL, and condensed chromatin; the pan-caspase inhibitor Z-VAD-FMK significantly raised viability. Both agents raised gamma-H2AX, phospho-RPA32 Ser 4/Ser 8 and phospho-CHK1 Ser 345; dl922-947 raised inactive phospho-CDK1 Tyr 15, which AZD1775 suppressed. The authors concluded the combination could be a feasible strategy against malignant mesothelioma.

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: in vitro laboratory experiment in human mesothelioma and normal mesothelial cell lines (drug plus oncolytic virus combination study)
• Who was studied: Human malignant mesothelioma cell lines NCI-H28 and MSTO-211H, plus the normal mesothelial cell line MET-5A, all purchased from ATCC; no patients or animals studied
• Exposure: Treatment of the mesothelioma lines with the oncolytic adenovirus dl922-947 and the WEE1 inhibitor AZD1775, alone and combined, around the 5-day IC50 values stated by the authors (dl922-947 IC50 values taken from their previous report); MET-5A was treated with the combination only
• Main results:
  • Isobologram analysis of the viability data showed synergism between AZD1775 and dl922-947 in both mesothelioma cell lines (combination index values less than 1 indicate synergism)
  • In the non-neoplastic MET-5A mesothelial line treated with the combination, there was only slight, not significant toxicity at 5 days
  • At 96 h in the mesothelioma lines, annexinV-positive cell percentages (early and late apoptotic/necrotic) were higher with dl922-947 plus AZD1775 than with dl922-947 alone; AZD1775 alone gave no significant increase
  • dl922-947, alone and with AZD1775, increased cleaved caspase-3 and decreased BCL-XL in both mesothelioma lines; co-treatment with the pan-caspase inhibitor Z-VAD-FMK significantly raised viability compared with dl922-947 alone
  • Both agents, alone and combined, increased gamma-H2AX, phospho-RPA32 Ser 4/Ser 8 and phospho-CHK1 Ser 345 in both mesothelioma cell lines
  • dl922-947 increased inactive Tyr-15-phosphorylated CDK1, and this increase was suppressed by AZD1775
• The authors' conclusion: The authors concluded that WEE1 inhibition with AZD1775 sensitizes mesothelioma cells to dl922-947 by abrogating the virus-induced DNA damage checkpoint, and that the combination could be a feasible strategy against malignant mesothelioma
• Limitations the authors state:
  • The authors state the combination has not yet been tested in animal models
  • The authors state that the exact mode of cell death induced by the virus in mesothelioma is not yet understood
  • The authors note the efficacy of the combination should be evaluated in animal models and compared with other mono- and combination therapies

Topics

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

Medical terms in this study, explained in our Lexicon: Malignant Mesothelioma, DNA lesions, 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)
• Not so WEE: targeting G₂/M to kill mesothelioma cells — P. Dent (2014)
• Pharmacological targeting of p53 through RITA is an effective antitumoral strategy for malignant pleural mesothelioma — D. Di Marzo, I.M. Forte, et al. (2014)
• RBL2/p130 is a direct AKT target and is required to induce apoptosis upon AKT inhibition in lung cancer and mesothelioma cell lines — F. Pentimalli, I.M. Forte, et al. (2018)
• The Oncolytic Virus dl922-947 Triggers Immunogenic Cell Death in Mesothelioma and Reduces Xenograft Growth — S. Di Somma, C.A. Iannuzzi, et al. (2019)
• FISH Analysis of Crizotinib Target Genes ROS1/ALK/MET in Malignant Mesothelioma — S. Salvi, S. Varesano, et al. (2017)

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