H3K9me3 represses G6PD expression to suppress the pentose phosphate pathway and ROS production to promote human mesothelioma growth

Our plain-English summary of H3K9me3 represses G6PD expression to suppress the pentose phosphate pathway and ROS production to promote human mesothelioma growth, by C. Lu, D. Yang, J.D. Klement, et al (Oncogene, 2022).

The study

• Authors: C. Lu, D. Yang, J.D. Klement, Y.L. Colson, N.H. Oberlies, C.J. Pearce, A.H. Colby, M.W. Grinstaff, Z. Liu, H. Shi, H.F. Ding, K. Liu
• Journal: Oncogene
• Published: 2022;41(18):2651-2662
• Cited by: 24 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The role of glucose-6-phosphate dehydrogenase (G6PD) in human cancer is incompletely understood. In a metabolite screening, we observed that inhibition of H3K9 methylation suppressed aerobic glycolysis and enhances the PPP in human mesothelioma cells. Genome-wide screening identified G6PD as an H3K9me3 target gene whose expression is correlated with increased tumor cell apoptosis. Inhibition of aerobic glycolysis enzyme LDHA and G6PD had no significant effects on tumor cell survival. Ablation of G6PD had no significant effect on human mesothelioma and colon carcinoma xenograft growth in athymic mice. However, activation of G6PD with the G6PD-selective activator AG1 induced tumor cell death. AG1 increased tumor cell ROS production and the resultant extrinsic and intrinsic death pathways, mitochondrial processes, and unfolded protein response in tumor cells. Consistent with increased tumor cell death in vitro, AG1 suppressed human mesothelioma xenograft growth in a dose-dependent manner in vivo. Furthermore, AG1 treatment significantly increased tumor-bearing mouse survival in an intra-peritoneum xenograft athymic mouse model. Therefore, in human mesothelioma and colon carcinoma, G6PD is not essential for tumor growth. G6PD acts as a metabolic checkpoint to control metabolic flux towards the PPP to promote tumor cell apoptosis, and its expression is repressed by its promotor H3K9me3 deposition.

© 2022. The Author(s), under exclusive licence to Springer Nature Limited.

In plain English

This was a laboratory study using human mesothelioma cell lines (epithelioid NCI-H226, biphasic MSTO-211H), a human colon carcinoma line (SW620) and athymic nude mouse xenografts. Treating NCI-H226 cells with the histone methyltransferase inhibitor verticillin A raised pentose phosphate pathway (PPP), amino acid and TCA metabolites, lowered intracellular and extracellular lactate, decreased the extracellular acidification rate and increased the oxygen consumption rate. RNA-sequencing and chromatin immunoprecipitation identified G6PD as up-regulated by verticillin A, with H3K9me3 enriched at the G6PD promoter and reduced after treatment. An LDHA inhibitor (GSK2837808A) and a G6PD inhibitor (G6PDi-1) did not cause significant tumour cell death, and CRISPR knockout of G6PD did not significantly affect cell viability or xenograft growth. The G6PD activator AG1 induced dose-dependent cell death, increased reactive oxygen species, and suppressed xenograft growth; in an intraperitoneal model median time to death was 21.5 days (95% CI 20 to 22 days) in controls and 23 days (95% CI 20 to 25 days) with AG1 (p=0.0122), with about 20% body weight loss at the efficacious dose.

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 study of human tumour cell lines with mouse xenograft experiments (cell culture, metabolomics, RNA-Seq, ChIP, CRISPR knockout, drug treatment in athymic nude mice)
• Who was studied: Human epithelioid mesothelioma NCI-H226, biphasic mesothelioma MSTO-211H and human colon carcinoma SW620 cell lines, plus female 7-8 week old Nu/J athymic nude mice; one de-identified human malignant mesothelioma tissue specimen was stained for G6PD
• Exposure: Pharmacological and genetic manipulation of metabolic/epigenetic targets: verticillin A (H3K9 methylation inhibitor), LDHA inhibitor GSK2837808A, G6PD inhibitor G6PDi-1, G6PD activator AG1 (20 and 40 mg/kg body weight in vivo), and CRISPR knockout of G6PD
• Main results:
  • In NCI-H226 cells, verticillin A increased PPP, amino acid and TCA metabolites and decreased lactate; intracellular glutamine increased more than 8-fold
  • In human mesothelioma cells, verticillin A lowered the extracellular acidification rate and raised the oxygen consumption rate
  • H3K9me3 was enriched at the G6PD promoter and verticillin A reduced that deposition in the mesothelioma cells
  • Inhibiting LDHA with GSK2837808A did not cause significant mesothelioma cell death in vitro
  • Inhibiting G6PD with G6PDi-1 also did not cause significant tumour cell death; the authors stated aerobic glycolysis and G6PD are not essential for mesothelioma cell survival
  • G6PD knockout did not significantly affect mesothelioma cell viability or xenograft growth, nor SW620 colon carcinoma xenografts
  • The G6PD activator AG1 caused dose-dependent mesothelioma cell death and raised reactive oxygen species; G6PD knockout reduced sensitivity to AG1
  • In the intraperitoneal NCI-H226 model, median time to death was 21.5 days (95% CI=20d-22d) in solvent controls and 23 days (95% CI:20d-25d) with AG1, p=0.0122; 8 of 10 control mice had enlarged abdomens and AG1 caused about 20% body weight loss
  • The median time to death in the AG1-treated group was 23 days with its confidence interval
• The authors' conclusion: The authors concluded that in human mesothelioma and colon carcinoma G6PD is not essential for tumour growth, that G6PD acts as a metabolic checkpoint directing flux to the PPP to promote tumour cell apoptosis, and that its expression is repressed by promoter H3K9me3 deposition; they stated that pharmacological activation of G6PD with AG1 is an effective approach to suppress human mesothelioma growth in vivo
• Limitations the authors state:
  • Only mesothelioma and colon carcinoma cell lines were studied, so G6PD function in other cancers is unknown
  • Verticillin A probably affects genes other than G6PD that contribute to apoptosis, and AG1's off-target effects and toxicity are not established
  • Sample size was taken from a previous study rather than a power analysis, and individual mice were not randomised (only cages were)

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, Apoptosis, Carcinoma, Peritoneum, Deposition.

Related studies

• Crocidolite asbestos inhibits pentose phosphate oxidative pathway and glucose 6-phosphate dehydrogenase activity in human lung epithelial cells — C. Riganti, E. Aldieri, et al. (2002)
• G6PD functions as a metabolic checkpoint to regulate granzyme B expression in tumor-specific cytotoxic T lymphocytes — C. Lu, D. Yang, et al. (2022)
• Restored expression of the MYO18B gene suppresses orthotopic growth and the production of bloody pleural effusion by human malignant pleural mesothelioma cells in SCID mice — N. Edakuni, K. Ikuta, et al. (2006)
• TAZ activation by Hippo pathway dysregulation induces cytokine gene expression and promotes mesothelial cell transformation — A. Matsushita, T. Sato, et al. (2019)
• FK228 suppress the growth of human malignant pleural mesothelioma tumor independent to epithelioid or non-epithelioid histology — J.M. Chan, Y.C. Chang, et al. (2024)
• TGF-β synergizes with defects in the Hippo pathway to stimulate human malignant mesothelioma growth — M. Fujii, T. Toyoda, et al. (2012)

Browse more research in Oncogene, or return to medical research.