Concurrent induction of apoptosis and necroptosis in apigenin‑treated malignant mesothelioma cells: Reversal of Warburg effect through Akt inhibition and p53 upregulation

Our plain-English summary of Concurrent induction of apoptosis and necroptosis in apigenin‑treated malignant mesothelioma cells: Reversal of Warburg effect through Akt inhibition and p53 upregulation, by Y.J. Lee, K.S. Park, S.H. Heo, et al (Oncology Reports, 2023).

The study

• Authors: Y.J. Lee, K.S. Park, S.H. Heo, M.K. Cho, S.H. Lee
• Journal: Oncology Reports
• Published: 2023;49(6)
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

A high dependence on aerobic glycolysis, known as the Warburg effect, is one of the metabolic features exhibited by tumor cells. Therefore, targeting glycolysis is becoming a very promising strategy for the development of anticancer drugs. In the present study, it was investigated whether pre‑adaptation of malignant mesothelioma (MM) cells to an acidic environment was associated with a metabolic shift to the Warburg phenotype in energy production, and whether apigenin targets acidosis‑driven metabolic reprogramming. Cell viability, glycolytic activity, Annexin V‑PE binding activity, reactive oxygen species (ROS) levels, mitochondrial membrane potential, ATP content, western blot analysis and spheroid viability were assessed in the present study. MM cells pre‑adapted to lactic acid were resistant to the anticancer drug gemcitabine, increased Akt activation, downregulated p53 expression, and upregulated rate‑limiting enzymes in glucose metabolism compared with their parental cells. Apigenin treatment increased cytotoxicity, Akt inactivation and p53 upregulation. Apigenin also reduced glucose uptake along with downregulation of key regulatory enzymes in glycolysis, increased ROS levels with loss of mitochondrial membrane potential, and downregulated the levels of complexes I, III and IV in the mitochondrial electron transport chain with intracellular ATP depletion, resulting in upregulation of molecules mediating apoptosis and necroptosis. Apigenin‑induced alterations of cellular responses were similar to those of Akt inactivation by Ly294002. Overall, the present results provide mechanistic evidence supporting the anti‑glycolytic and cytotoxic role of apigenin via inhibition of the PI3K/Akt signaling pathway and p53 upregulation.

In plain English

This laboratory study used two human malignant mesothelioma cell lines. The authors adapted the cells to an acidic environment by growing them with lactic acid. They then tested the compound apigenin at 30 µM and Ly294002, a chemical that blocks the Akt signaling pathway, at 20 µM, alone or together, for 48 hours. For the combination, Ly294002 was added 2 hours before apigenin and left in the medium. No people, animals or asbestos exposures were studied. The acid-adapted cells grew faster and tolerated the cancer drug gemcitabine better than the original cells. Apigenin alone reduced cell viability to 76.19% in acid-adapted MSTO-211H cells and to 82.81% in acid-adapted H2452 cells, compared with control cells given only dimethyl sulfoxide (DMSO). Both treatments increased markers of two forms of cell death (apoptosis and necroptosis), lowered glucose use and reduced cellular energy (ATP). Combining the two treatments showed no synergistic effect on viability. Three-dimensional cell clusters were less sensitive. The authors concluded that apigenin acted against glycolysis and killed cells by inhibiting the PI3K/Akt pathway and raising p53. They noted that the lack of animal data was a limitation.

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) cell-culture experiment, including 2D monolayer and 3D spheroid cultures
• Who was studied: Two commercially obtained human malignant mesothelioma cell lines, MSTO-211H and H2452. Versions pre-adapted to lactic acid (MSTO-211HAcT and H2452AcT) were made by exposing the cells to 3.8 µM lactic acid through 4 passages over 15 days. No human participants or animals were involved.
• Exposure: Apigenin (30 µM) and the PI3K/Akt inhibitor Ly294002 (20 µM), alone or in combination, for 48 h, in medium containing lactic acid. For the combination, cells were pretreated with Ly294002 for 2 h and apigenin was then added without removing Ly294002. Control cells received 0.1% dimethyl sulfoxide. Gemcitabine was also tested on the cells. No asbestos or other fiber exposure was studied.
• Main results:
  • Compared with their parental cells, the lactic acid pre-adapted cells grew significantly faster and were more tolerant of gemcitabine.
  • The pre-adapted cells showed significantly higher p-Akt and lower p53.
  • The apigenin concentration that reduced viability by half (half maximal inhibitory concentration) was 47.17 µM in MSTO-211HAcT cells and 56.01 µM in H2452AcT cells.
  • Compared with control cells (treated with 0.1% dimethyl sulfoxide), apigenin alone reduced cell viability to 76.19% in MSTO-211HAcT cells and to 82.81% in H2452AcT cells. Ly294002 alone reduced it to 79.59% and 83.80%, respectively.
  • Combining apigenin and Ly294002 did not show a synergistic effect on cell viability compared with either treatment alone.
  • Apigenin and Ly294002, alone or combined, inhibited Akt phosphorylation and raised p53 levels.
  • Compared with controls, apoptotic cells (early and late) rose to 19.30% with apigenin and 18.03% with Ly294002 in MSTO-211HAcT cells. In H2452AcT cells they rose to 15.49% and 14.76%, respectively.
  • Proteins linked to apoptosis (cleaved caspase-3, cleaved PARP) and to necroptosis (p-MLKL, p-RIP3) increased with either treatment, and more so with the combination.
  • Glucose left in the culture medium increased by 46.91% with apigenin and 20.58% with Ly294002 in MSTO-211HAcT cells, and by 32.43% and 14.91%, respectively, in H2452AcT cells. The authors interpreted this as reduced glucose use.
  • Mitochondrial electron transport chain complexes and intracellular ATP were significantly reduced by either treatment alone, and further reduced by the combination.
  • Cells grown as 3D spheroids showed similar trends but were less sensitive to the treatments than cells in 2D cultures.
• The authors' conclusion: The authors concluded that their results provide mechanistic evidence that apigenin acts against glycolysis and is cytotoxic to these mesothelioma cells by inhibiting the PI3K/Akt pathway and upregulating p53.
• Limitations the authors state:
  • The study had no in vivo (animal) data, and the authors stated that animal studies are needed to confirm the cell-culture effects.

Topics

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

Medical terms in this study, explained in our Lexicon: Apoptosis, Mesothelioma, Reactive Oxygen Species (ROS), Gemcitabine.

Related studies

• Hexokinase II as a Potential Target of Apigenin Through the Induction of Apoptosis and Necroptosis in Malignant Mesothelioma — M.K. Cho, S.H. Lee, et al. (2026)
• Pifithrin-μ induces necroptosis through oxidative mitochondrial damage but accompanies epithelial-mesenchymal transition-like phenomenon in malignant mesothelioma cells under lactic acidosis — Y.J. Lee, K.S. Park, et al. (2019)
• Reactive oxygen species and PI3K/Akt signaling play key roles in the induction of Nrf2-driven heme oxygenase-1 expression in sulforaphane-treated human mesothelioma MSTO-211H cells — Y.J. Lee, H.Y. Jeong, et al. (2012)
• Apigenin causes necroptosis by inducing ROS accumulation, mitochondrial dysfunction, and ATP depletion in malignant mesothelioma cells — Y.J. Lee, K.S. Park, et al. (2020)
• Cariporide Enhances the DNA Damage and Apoptosis in Acid-tolerable Malignant Mesothelioma H-2452 Cells — Y.J. Lee, J.H. Bae, et al. (2017)
• Pro-oxidant activity of sulforaphane and cisplatin potentiates apoptosis and simultaneously promotes autophagy in malignant mesothelioma cells — Y.J. Lee, S.H. Lee (2017)

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