Lysosomal nitric oxide determines transition from autophagy to ferroptosis after exposure to plasma-activated Ringer's lactate

Our plain-English summary of Lysosomal nitric oxide determines transition from autophagy to ferroptosis after exposure to plasma-activated Ringer's lactate, by L. Jiang, H. Zheng, Q. Lyu, et al (Redox Biology, 2021).

The study

• Authors: L. Jiang, H. Zheng, Q. Lyu, S. Hayashi, K. Sato, Y. Sekido, K. Nakamura, H. Tanaka, K. Ishikawa, H. Kajiyama, M. Mizuno, M. Hori, S. Toyokuni
• Journal: Redox Biology
• Published: 2021;43:101989
• Cited by: 82 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Non-thermal plasma (NTP), an engineered technology to generate reactive species, induces ferroptosis and/or apoptosis specifically in various-type cancer cells. NTP-activated Ringer's lactate (PAL) is another modality for cancer therapy at preclinical stage. Here we found that PAL induces selective ferroptosis of malignant mesothelioma (MM) cells, where non-targeted metabolome screening identified upregulated citrulline-nitric oxide (.NO) cycle as a PAL target. .NO probe detected biphasic peaks transiently at PAL exposure with time-dependent increase, which was responsible for inducible . NO synthase (iNOS) overexpression through NF-κB activation. .NO and lipid peroxidation occupied lysosomes as a major compartment with increased TFEB expression. Not only ferrostatin-1 but inhibitors for . NO and/or iNOS could suppress this ferroptosis. PAL-induced ferroptosis accompanied autophagic process in the early phase, as demonstrated by an increase in essential amino acids, LC3B-II, p62 and LAMP1, transforming into the later phase with boosted lipid peroxidation. Therefore, .NO-mediated lysosomal impairment is central in PAL-induced ferroptosis.

Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.

In plain English

This was a laboratory study of human cells grown in dishes. No patients or animals were studied, and asbestos was not tested; the authors mention it only as background on malignant mesothelioma. The authors treated two human malignant mesothelioma cell lines (H290, sarcomatoid subtype; 8A, epithelioid subtype) and normal human mesothelial cells (LP9) with Ringer's lactate solution activated by non-thermal plasma (PAL). PAL made with a 10% nitrogen, 10% oxygen, 80% argon gas mix had significant anti-proliferative effects on the mesothelioma cells without disturbing the proliferation of the normal LP9 cells. H290 cells were more sensitive than 8A cells. Ferrostatin-1, a blocker of an iron-dependent cell death called ferroptosis, prevented PAL-induced death but not death caused by cisplatin. In mesothelioma cells, PAL raised nitric oxide levels and the enzyme iNOS; PAL did not induce iNOS in normal cells. Nitric oxide and lipid peroxidation accumulated in lysosomes, and blockers of nitric oxide or iNOS reduced the cell death. The authors concluded that PAL induces ferroptosis in mesothelioma cells through nitric-oxide-related lipid peroxidation in lysosomes. They noted that the effects may differ by cancer type.

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) experimental study using human cell lines
• Who was studied: Human malignant mesothelioma cell lines NCI-H290 (sarcomatoid subtype) and Y-Meso-8A (epithelioid subtype); a human normal mesothelial cell line (LP9); and, in supplementary experiments, a human fibrosarcoma cell line (HT1080). Experiments were generally run in triplicate (N = 3).
• Exposure: Non-thermal plasma-activated Ringer's lactate (PAL), diluted 14-fold and applied to cells for 15 minutes. Comparisons were made with untreated Ringer's lactate, erastin and cisplatin, with or without inhibitors (ferrostatin-1, carboxy-PTIO, 1400 W, bafilomycin A1). No asbestos exposure was studied.
• Main results:
  • PAL made with 10% N2/10% O2/80% Ar had significant anti-proliferative effects on mesothelioma cells but did not disturb proliferation of normal LP9 mesothelial cells
  • H290 (sarcomatoid) cells were more sensitive to PAL than 8A (epithelioid) cells
  • Ferrostatin-1 (a ferroptosis inhibitor) prevented PAL-induced death of H290 and 8A cells
  • Ferrostatin-1 did not reverse cell death caused by cisplatin
  • In mesothelioma cells, nitric oxide rose immediately at 30 minutes after PAL and dipped at 1 hour, followed by a persistent time-dependent rise
  • PAL did not induce iNOS in normal LP9 mesothelial cells
  • A nitric oxide scavenger (carboxy-PTIO) and an iNOS inhibitor (1400 W) significantly reversed PAL-induced ferroptosis in mesothelioma cells
  • In PAL-treated mesothelioma cells, nitric oxide and lipid peroxidation accumulated in lysosomes
  • The nitric oxide and iNOS blockers did not reverse erastin-induced ferroptosis
  • In H290 cells, 8 of 9 essential amino acids increased after PAL, consistent with an early autophagic process
  • Bafilomycin A1 protected mesothelioma cells from PAL-induced ferroptosis
• The authors' conclusion: The authors concluded that PAL induces ferroptosis in malignant mesothelioma cells through lipid peroxidation in lysosomes driven by oxidants derived from nitric oxide.
• Limitations the authors state:
  • The effects of PAL may be specific to cancer histology or origin, since a previous report in lung adenocarcinoma cells found a different mechanism; the authors said further investigation is needed

Topics

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

Related studies

• Non-thermal plasma induces a stress response in mesothelioma cells resulting in increased endocytosis, lysosome biogenesis and autophagy — L. Shi, F. Ito, et al. (2017)
• Carbonic anhydrase 9 confers resistance to ferroptosis/apoptosis in malignant mesothelioma under hypoxia — Z. Li, L. Jiang, et al. (2019)
• Ferroptosis-dependent extracellular vesicles from macrophage contribute to asbestos-induced mesothelial carcinogenesis through loading ferritin — F. Ito, K. Kato, et al. (2021)
• Iron addiction with ferroptosis-resistance in asbestos-induced mesothelial carcinogenesis: Toward the era of mesothelioma prevention — S. Toyokuni (2019)
• Asbestos conceives Fe(II)-dependent mutagenic stromal milieu through ceaseless macrophage ferroptosis and β-catenin induction in mesothelium — F. Ito, I. Yanatori, et al. (2020)
• Intercellular interaction dictates cancer cell ferroptosis via NF2-YAP signalling — J. Wu, A.M. Minikes, et al. (2019)

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