Disturbance of the Warburg effect by dichloroacetate and niclosamide suppresses the growth of different sub-types of malignant pleural mesothelioma in vitro and in vivo

Our plain-English summary of Disturbance of the Warburg effect by dichloroacetate and niclosamide suppresses the growth of different sub-types of malignant pleural mesothelioma in vitro and in vivo, by S.K. Lam, S. Yan, J.S. Lam, et al (Frontiers in Pharmacology, 2022).

The study

• Authors: S.K. Lam, S. Yan, J.S. Lam, Y. Feng, M. Khan, C. Chen, F.C. Ko, J.C. Ho
• Journal: Frontiers in Pharmacology
• Published: 2022;13:1020343
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Inhalation of asbestos fibers is the most common cause of malignant pleural mesothelioma (MPM). In 2004, the United States Food and Drug Administration approved a combination of cisplatin with pemetrexed to treat unresectable MPM. Nonetheless novel treatment is urgently needed. The objective of this study is to report the combination effect of dichloroacetate (DCA) or niclosamide (Nic) Nic in MPM. Materials and methods: The effect of a combination of DCA and Nic was studied using a panel of MPM cell lines (H28, MSTO-211H, H226, H2052, and H2452). Cell viability was monitored by MTT assay. Glycolysis, oxidative phosphorylation, glucose, glycogen, pyruvate, lactate, citrate, succinate and ATP levels were determined by corresponding ELISA. Apoptosis, mitochondrial transmembrane potential, cell cycle analysis, hydrogen peroxide and superoxide were investigated by flow cytometry. Cell migration and colony formation were investigated by transwell migration and colony formation assays respectively. The in vivo effect was confirmed using 211H and H226 nude mice xenograft models. Results and conclusion: Cell viability was reduced. Disturbance of glycolysis and/or oxidative phosphorylation resulted in downregulation of glycogen, citrate and succinate. DCA and/or Nic increased apoptosis, mitochondrial transmembrane depolarization, G2/M arrest and reactive oxygen species. Moreover, DCA and/or Nic suppressed cell migration and colony formation. Furthermore, a better initial tumor suppressive effect was induced by the DCA/Nic combination compared with either drug alone in both 211H and H226 xenograft models. In H226 xenografts, DCA/Nic increased median survival of mice compared with single treatment. Single drug and/or a combination disturbed the Warburg effect and activated apoptosis, and inhibition of migration and proliferation in vivo. In conclusion, dichloroacetate and/or niclosamide showed a tumor suppressive effect in MPM in vitro and in vivo, partially mediated by disturbance of glycolysis/oxidative phosphorylation, apoptosis, ROS production, G2/M arrest, and suppression of migration and proliferation.

Copyright © 2022 Lam, Yan, Lam, Feng, Khan, Chen, Ko and Ho.

In plain English

This laboratory study tested two existing drugs, dichloroacetate (DCA) and niclosamide, against malignant pleural mesothelioma. It did not study asbestos exposure or treat any patients. The authors used five human mesothelioma cell lines of sarcomatoid, biphasic and epithelioid types. They also used mice carrying human tumours grown from two of those lines. Each drug alone reduced cell survival. Together, the two drugs had a synergistic effect in all five cell lines, the authors reported. The drugs changed how cells used sugar and oxygen. Niclosamide and the combination increased apoptosis (a form of programmed cell death) in some cell lines. DCA alone did not, and no treatment increased apoptosis in H28 cells. The drugs also raised reactive oxygen molecules and growth arrest and cut cell movement, varying by drug and cell line. In mice with 211H tumours, median survival was 29 days with DCA or the combination, against 22 days with solvent or niclosamide alone. In mice with H226 tumours, it was 26 days with the combination against 22 days in the other groups. The authors concluded that the combination inhibited mesothelioma in cells and mice.

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 (original research) using human mesothelioma cell lines and mouse xenograft models, meaning human tumour cells grown in mice. It was not a study of people.
• Who was studied: Five purchased human mesothelioma cell lines: NCI-H28 and NCI-H2052 (sarcomatoid), MSTO-211H (biphasic), and NCI-H226 and NCI-H2452 (epithelioid). Nude mice were given tumours from the 211H and H226 lines. The work was done at the University of Hong Kong.
• Exposure: No asbestos exposure was studied; asbestos appears only as background. Cells and mice were treated with sodium dichloroacetate (DCA), niclosamide (Nic), or both. In mice, the treatments were given daily by injection into the abdomen, and the control group received solvent only.
• Main results:
  • After 72 hours of single-drug treatment, the concentration halving cell viability (IC50) was as follows. For DCA: 20, 21, 20, 23 and 25 mM. For niclosamide: 2, 2, 3, 3 and 2.5 μM. These figures are for the H28, 211H, H226, H2052 and H2452 cells respectively.
  • The combination of DCA and niclosamide showed a synergistic anti-cancer effect in all 5 cell lines and synergistically inhibited colony formation.
  • With the combination, the IC50 fell to 10, 7.5, 8, 8 and 10.5 (DCA) or 1, 0.75, 0.8, 0.8 and 1.1 (niclosamide) in the same five cell lines. Units were not printed for these values.
  • In short-term (4-hour) tests in cells, glycolysis rose with the combination, while intracellular glycogen, citrate and succinate fell. The authors interpreted this as the Warburg effect being enhanced. This effect was driven mainly by niclosamide.
  • Apoptosis depended on both the treatment and the cell line. No treatment changed the number of apoptotic cells in H28 cells.
  • DCA alone did not induce apoptosis in the mesothelioma cell lines. Niclosamide and/or the combination induced apoptosis in the other four cell lines.
  • The combination raised hydrogen peroxide in all cell lines and superoxide in most.
  • The combination caused G2/M growth arrest in all cell lines.
  • Cell migration was reduced in some cell lines. Invasive ability was low to begin with and was not changed by any treatment.
  • In mice with 211H tumours, median survival was 29 days in the DCA and combination groups, compared with 22 days in the control and niclosamide groups.
  • In mice with H226 tumours, median survival was 26 days with the combination, compared with 22 days in the control, DCA and niclosamide groups.
  • In 211H tumours in mice, glycogen, citrate and succinate rose with single and combined treatment, the opposite of the cell results. In H226 tumours, they fell with niclosamide and with the combination.
  • In public mesothelioma patient data (The Cancer Genome Atlas), higher expression of PFKP (printed once as 'PFKB') and LDHB went with lower median survival, with p = 0.086 and p less than 0.0001 respectively. The authors worded this as 'resulted in'.
• The authors' conclusion: The authors concluded that DCA and niclosamide together synergistically inhibited different subtypes of malignant pleural mesothelioma in cells and in mice. They attributed this partly to disturbed glycolysis and oxidative phosphorylation, apoptosis, reduced proliferation, G2/M arrest, reactive oxygen species and/or inhibited migration.
• Limitations the authors state:
  • The glycolysis test measured lactate outside the cells and could not be used in the mouse tumours.
  • The authors acknowledged that the metabolite results in 211H mouse tumours were paradoxical compared with the cell results.

Topics

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Cisplatin, Pemetrexed (Alimta), Unresectable, Apoptosis, Superoxide, Reactive Oxygen Species (ROS), Median Overall Survival.

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