A Selective ALDH1A3 Inhibitor Impairs Mesothelioma 3-D Multicellular Spheroid Growth and Neutrophil Recruitment

Our plain-English summary of A Selective ALDH1A3 Inhibitor Impairs Mesothelioma 3-D Multicellular Spheroid Growth and Neutrophil Recruitment, by S. Boumya, S. Fallarini, S. Siragusa, et al (International Journal of Molecular Sciences, 2023).

The study

• Authors: S. Boumya, S. Fallarini, S. Siragusa, G. Petrarolo, S. Aprile, V. Audrito, C. La Motta, S. Garavaglia, L. Moro, G. Pinton
• Journal: International Journal of Molecular Sciences
• Published: 2023;24(7)
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Aldehyde dehydrogenase 1A3 (ALDH1A3), one of the three members of the aldehyde dehydrogenase 1A subfamily, has been associated with increased progression and drug resistance in various types of solid tumours. Recently, it has been reported that high ALDH1A3 expression is prognostic of poor survival in patients with malignant pleural mesothelioma (MPM), an asbestos-associated chemoresistant cancer. We treated MPM cells, cultured as multicellular spheroids, with NR6, a potent and highly selective ALDH1A3 inhibitor. Here we report that NR6 treatment caused the accumulation of toxic aldehydes, induced DNA damage, CDKN2A expression and cell growth arrest. We observed that, in CDKN2A proficient cells, NR6 treatment induced IL6 expression, but abolished CXCL8 expression and IL-8 release, preventing both neutrophil recruitment and generation of neutrophil extracellular traps (NETs). Furthermore, we demonstrate that in response to ALDH1A3 inhibition, CDKN2A loss skewed cell fate from senescence to apoptosis. Dissecting the role of ALDH1A3 isoform in MPM cells and tumour microenvironment can open new fronts in the treatment of this cancer.

In plain English

This was a laboratory study of cells, not patients or asbestos exposure. The authors grew three malignant pleural mesothelioma cell lines (REN, MSTO-211H and H2596) as three-dimensional clusters (spheroids) and treated them with NR6, an experimental compound that blocks the enzyme ALDH1A3. The enzyme was found in H2596 and, at higher levels, MSTO-211H cells, but not in REN or NP2 mesothelial cells. NR6 had no significant effect on the viability of REN or NP2 cells. In MSTO-211H spheroids, NR6 significantly reduced viable cell numbers, raised a toxic aldehyde called malondialdehyde and a marker suggesting DNA damage, and switched on the gene CDKN2A. The authors attributed the fall in cell numbers to senescent growth arrest, not apoptotic death. Treated spheroids released less IL-8 and drew in fewer neutrophils, which are white blood cells taken from healthy donors. Where CDKN2A was silenced, or absent as in H2596 cells, NR6 instead caused programmed cell death (apoptosis). The authors concluded that ALDH1A3 is an attractive treatment target in mesothelioma. They said the results need validation in models closer to conditions in the body.

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 (in vitro) study of mesothelioma cell lines grown as multicellular spheroids and treated with an experimental compound
• Who was studied: Three malignant pleural mesothelioma cell lines: REN (epithelioid), MSTO-211H (biphasic) and H2596 (sarcomatoid). Also NP2 mesothelial cells, and neutrophils isolated from the blood of healthy volunteers.
• Exposure: Treatment with NR6, an experimental selective ALDH1A3 inhibitor, at 1 µM, mostly for 72 hours. Asbestos exposure was not studied.
• Main results:
  • ALDH1A3 was expressed in H2596 spheroids and at higher levels in MSTO-211H spheroids, but not in REN cells.
  • In MSTO-211H spheroids, NR6 significantly reduced the number of viable cells.
  • In REN and NP2 cells, which lack ALDH1A3, NR6 had no significant effect on viability.
  • In MSTO-211H spheroids, NR6 caused malondialdehyde (a toxic aldehyde) to build up inside the cells.
  • In MSTO-211H spheroids, the fall in cell number with NR6 was not due to apoptotic death, as shown by the absence of PARP-1 cleavage.
  • In MSTO-211H spheroids, NR6 switched on CDKN2A and IL6. The authors took this as suggesting a secretory senescent phenotype.
  • NR6-treated MSTO-211H spheroids released significantly less IL-8 than untreated controls.
  • NR6 significantly reduced the number of neutrophils entering MSTO-211H spheroids.
  • Neutrophils from healthy donors did not express ALDH1A3, and NR6 did not affect their viability.
  • Neutrophils that entered untreated MSTO-211H spheroids underwent NETosis, which means they released neutrophil extracellular traps.
  • In MSTO-211H cells with CDKN2A silenced, NR6 caused apoptosis.
  • In H2596 spheroids, which have homozygous deletion of CDKN2A, NR6 caused apoptosis.
  • In NR6-treated H2596 spheroids, IL-8 release and neutrophil recruitment were reduced compared with controls.
• The authors' conclusion: The authors concluded that their findings present ALDH1A3 as an attractive target for treating malignant pleural mesothelioma.
• Limitations the authors state:
  • The results should be further validated in 3D culture models in which spheroids form within matrices, to better mimic conditions in the body.
  • The type and effects of the neutrophils recruited into the spheroids still need to be characterized.
  • The different responses of IL6 and CXCL8 to NR6 need further investigation.

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, Pleural Mesothelioma, CDKN2A, Apoptosis.

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• Paclitaxel-loaded expansile nanoparticles enhance chemotherapeutic drug delivery in mesothelioma 3-dimensional multicellular spheroids — H. Lei, S.C. Hofferberth, et al. (2015)
• Pharmacological inhibition of CDK4/6 impairs diffuse pleural mesothelioma 3D spheroid growth and reduces viability of cisplatin-resistant cells — A. Costa, I.M. Forte, et al. (2024)
• 2-Deoxy-glucose Enhances the Effect of Cisplatin and Pemetrexed in Reducing Malignant Pleural Mesothelioma Cell Proliferation But Not Spheroid Growth — I. Gerogianni, E. Pitaraki, et al. (2019)
• Antagonizing the Hedgehog Pathway with Vismodegib Impairs Malignant Pleural Mesothelioma Growth In Vivo by Affecting Stroma — M. Meerang, K. Bérard, et al. (2016)

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