Metabolic Characterization of Antifolate Responsiveness and Non-responsiveness in Malignant Pleural Mesothelioma Cells

Our plain-English summary of Metabolic Characterization of Antifolate Responsiveness and Non-responsiveness in Malignant Pleural Mesothelioma Cells, by Y. Sato, S. Matsuda, A. Maruyama, et al (Frontiers in Pharmacology, 2018).

The study

• Authors: Y. Sato, S. Matsuda, A. Maruyama, J. Nakayama, T. Miyashita, H. Udagawa, S. Umemura, K. Yanagihara, A. Ochiai, M. Tomita, T. Soga, K. Tsuchihara, H. Makinoshima
• Journal: Frontiers in Pharmacology
• Published: 2018;9:1129
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Antifolates are a class of drugs effective for treating malignant pleural mesothelioma (MPM). The majority of antifolates inhibit enzymes involved in purine and pyrimidine synthesis such as dihydrofolate reductase (DHFR), thymidylate synthase (TYMS), and glycinamide ribonucleotide formyltransferase (GART). In order to select the most suitable patients for effective therapy with drugs targeting specific metabolic pathways, there is a need for better predictive metabolic biomarkers. Antifolates can alter global metabolic pathways in MPM cells, yet the metabolic profile of treated cells has not yet been clearly elucidated. Here we found that MPM cell lines could be categorized into two groups according to their sensitivity or resistance to pemetrexed treatment. We show that pemetrexed susceptibility could be reversed and DNA synthesis rescued in drug-treated cells by the exogenous addition of the nucleotide precursors hypoxanthine and thymidine (HT). We observed that the expression of pemetrexed-targeted enzymes in resistant MPM cells was quantitatively lower than that seen in pemetrexed-sensitive cells. Metabolomic analysis revealed that glycine and choline, which are involved in one-carbon metabolism, were altered after drug treatment in pemetrexed-sensitive but not resistant MPM cells. The addition of HT upregulated the concentration of inosine monophosphate (IMP) in pemetrexed-sensitive MPM cells, indicating that the nucleic acid biosynthesis pathway is important for predicting the efficacy of pemetrexed in MPM cells. Our data provide evidence that may link therapeutic response to the regulation of metabolism, and points to potential biomarkers for informing clinical decisions regarding the most effective therapies for patients with MPM.

In plain English

This was a laboratory study of human malignant pleural mesothelioma cells grown in dishes, not of patients. It tested the chemotherapy drug pemetrexed. The authors measured how much drug was needed to halve cell survival in 8 mesothelioma cell lines, three of them established from Japanese patients. This amount ranged from 47.4 nM in the most sensitive line, MSTO-211H, to more than 10,000 nM in NCI-H2452, which the authors used as the resistant line. Adding hypoxanthine plus thymidine, building blocks for DNA, completely reversed the drug's growth-blocking effect. Two sensitive lines had higher levels of the drug's target enzymes GART and TYMS than the resistant line. The difference for DHFR protein was not statistically significant. After treatment, glycine fell and choline built up in the sensitive cells but not in the resistant line. A substance called IMP rose in sensitive cells given the drug together with hypoxanthine and thymidine. The authors concluded that glycine and IMP levels are potential markers of response to pemetrexed, and said this still needs testing in patient samples. The study did not examine asbestos exposure.

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 human mesothelioma cell lines, using drug-sensitivity tests, gene and protein measurements and metabolite profiling
• Who was studied: 8 human malignant pleural mesothelioma (MPM) cell lines. Five were purchased commercially: MSTO-211H, NCI-H28, NCI-H226, NCI-H2052 and NCI-H2452. Three (TCC-MESO1, TCC-MESO2, TCC-MESO3) were established from Japanese patients with MPM. Later experiments used MSTO-211H and TCC-MESO2 as sensitive lines and NCI-H2452 as the resistant line.
• Exposure: The exposure studied was the drug pemetrexed, not asbestos. Pemetrexed was given at various concentrations for 72 hours, and at 1 µM for 6 hours for the metabolite and cell-cycle work. It was given with or without 100 µM hypoxanthine and/or 16 µM thymidine. In the resistant line, 0.1 mM MTA was also tested.
• Main results:
  • Across the 8 cell lines, the pemetrexed concentration that halved cell viability (IC50) ranged from 47.4 nM (MSTO-211H) to more than 10,000 nM (NCI-H2452).
  • Hypoxanthine plus thymidine together completely reversed the growth suppression caused by pemetrexed.
  • mRNA levels of DHFR, GART and TYMS were higher in the sensitive lines than in resistant NCI-H2452. DHFR was 4.7-fold higher in MSTO-211H and 6.5-fold in TCC-MESO2. GART was 35.5-fold and 23.0-fold higher. TYMS was 2.3-fold and 1.9-fold higher.
  • At the protein level, GART was 3.4-fold (MSTO-211H) and 3.3-fold (TCC-MESO2) higher than in NCI-H2452, and TYMS was 71.9-fold and 81.4-fold higher.
  • Differences in DHFR protein between the sensitive lines and the resistant line were not statistically significant (P = 0.055).
  • A measure of glycolysis (ECAR) did not differ statistically between sensitive and resistant cells, with or without pemetrexed.
  • After pemetrexed treatment, glycine decreased and choline accumulated in the sensitive cells, but not in resistant NCI-H2452 cells.
  • IMP increased in the sensitive cells treated with pemetrexed plus hypoxanthine and thymidine, but not in resistant NCI-H2452 cells.
  • MTAP gene expression was detected in the two sensitive lines but not in resistant NCI-H2452.
  • In NCI-H2452 cells, MTA alone reduced cell survival. MTA combined with pemetrexed made the cells more resistant to pemetrexed.
• The authors' conclusion: The authors concluded that their results link the response to antifolate drugs to the regulation of cell metabolism. They wrote that glycine and IMP levels are potential biomarkers.
• Limitations the authors state:
  • The authors stated that nucleic acid metabolites would still need to be analyzed in clinical samples to test whether they predict treatment response.
  • The authors stated that further investigation is needed into the mechanisms controlling glycine metabolism in MPM cells.

Topics

Medical terms in this study, explained in our Lexicon: Antifolate, Pleural Mesothelioma, Biomarker, Pemetrexed (Alimta).

Related studies

• The influence of mineral dusts on metabolic co-operation between mammalian cells in tissue culture — M. Chamberlain (1982)
• Effect of mineral dusts on metabolic cooperation between Chinese hamster V79 cells in vitro — M. Chamberlain (1983)
• Long-Chain Acyl Coenzyme A Dehydrogenase, a Key Player in Metabolic Rewiring/Invasiveness in Experimental Tumors and Human Mesothelioma Cell Lines — D.L. Pouliquen, G. Ortone, et al. (2023)
• Metabolomics of a cell line-derived xenograft model reveals circulating metabolic signatures for malignant mesothelioma — Y. Gao, Z. Dai, et al. (2022)
• Quercetin-Arctigenin Co-Treatment Induces Mitochondrial Dysfunction and Apoptotic Cell Death Through Metabolic Stress in Malignant Mesothelioma Cells — M.K. Cho, S.H. Lee, et al. (2026)
• Pemetrexed disodium: a novel antifolate clinically active against multiple solid tumors — A.R. Hanauske, V. Chen, et al. (2001)

Browse more research in Frontiers in Pharmacology, or return to medical research.