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Receptor-Mediated Mitophagy Rescues Cancer Cells under Hypoxic Conditions
SIMPLE SUMMARY: Stimulation of cell death is a promising strategy for tumor cell elimination. Many tumors develop under hypoxic conditions, which alter tumor cell biology and makes them resistant to cell death stimuli. One of the mechanisms responsible for tumor cell resistance to treatment could be...
Autores principales: | , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2021
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8394032/ https://www.ncbi.nlm.nih.gov/pubmed/34439183 http://dx.doi.org/10.3390/cancers13164027 |
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author | Abdrakhmanov, Alibek Yapryntseva, Maria A. Kaminskyy, Vitaliy O. Zhivotovsky, Boris Gogvadze, Vladimir |
author_facet | Abdrakhmanov, Alibek Yapryntseva, Maria A. Kaminskyy, Vitaliy O. Zhivotovsky, Boris Gogvadze, Vladimir |
author_sort | Abdrakhmanov, Alibek |
collection | PubMed |
description | SIMPLE SUMMARY: Stimulation of cell death is a promising strategy for tumor cell elimination. Many tumors develop under hypoxic conditions, which alter tumor cell biology and makes them resistant to cell death stimuli. One of the mechanisms responsible for tumor cell resistance to treatment could be the stimulation of mitophagy (mitochondrial quality control), which eliminates mitochondria that can trigger the mitochondrial pathway in apoptosis. We found that hypoxia stimulates mitophagy via enhanced expression of BNIP3 and BNIP3L proteins, which are involved in receptor-mediated mitophagy. ABSTRACT: Targeting mitochondria with thenoyltrifluoroacetone (TTFA), an inhibitor of Complex II in the respiratory chain, stimulated cisplatin-induced apoptosis in various cell lines in normoxia but not in hypoxia. This can be explained by the elimination of mitochondria involved in triggering apoptotic cell death by mitophagy, either Parkin-dependent or receptor-mediated. Treatment with TTFA alone or in combination with cisplatin did not cause accumulation of PINK1, meaning that under hypoxic conditions cells survive through activation of a receptor-mediated pathway. Hypoxia triggers the accumulation of BNIP3 and BNIP3L (also known as NIX), key participants in receptor-mediated mitophagy. Under hypoxic conditions, stimulation of autophagy, as assessed by the accumulation of lipidated form of LC3 (LC3II), was observed. To exclude the contribution of canonical macroautophagy in LC3II accumulation, experiments were performed using U1810 cells lacking ATG13, a key enzyme of macroautophagy. Despite the absence of ATG13, hypoxia-mediated accumulation of LC3II was not affected, underlying the importance of the receptor-mediated pathway. In order to prove the protective role of BNIP3 against cisplatin-induced apoptosis, BNIP3-deficient A549 cells were used. Surprisingly, a BNIP3 knockout did not abolish hypoxia-induced protection; however, in cells lacking BNIP3, a compensatory upregulation of BNIP3L was detected. Thus, in the absence of BNIP3, mitophagy could be maintained by BNIP3L and lead to cell death suppression due to the elimination of proapoptotic mitochondria. When both BNIP3 and BNIP3L were knocked out, the inhibitory effect of hypoxia on apoptosis was diminished, although not abolished completely. Undoubtedly, receptor-mediated mitophagy is likely to be one of the mechanisms responsible for cell death suppression under hypoxic conditions. |
format | Online Article Text |
id | pubmed-8394032 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-83940322021-08-28 Receptor-Mediated Mitophagy Rescues Cancer Cells under Hypoxic Conditions Abdrakhmanov, Alibek Yapryntseva, Maria A. Kaminskyy, Vitaliy O. Zhivotovsky, Boris Gogvadze, Vladimir Cancers (Basel) Article SIMPLE SUMMARY: Stimulation of cell death is a promising strategy for tumor cell elimination. Many tumors develop under hypoxic conditions, which alter tumor cell biology and makes them resistant to cell death stimuli. One of the mechanisms responsible for tumor cell resistance to treatment could be the stimulation of mitophagy (mitochondrial quality control), which eliminates mitochondria that can trigger the mitochondrial pathway in apoptosis. We found that hypoxia stimulates mitophagy via enhanced expression of BNIP3 and BNIP3L proteins, which are involved in receptor-mediated mitophagy. ABSTRACT: Targeting mitochondria with thenoyltrifluoroacetone (TTFA), an inhibitor of Complex II in the respiratory chain, stimulated cisplatin-induced apoptosis in various cell lines in normoxia but not in hypoxia. This can be explained by the elimination of mitochondria involved in triggering apoptotic cell death by mitophagy, either Parkin-dependent or receptor-mediated. Treatment with TTFA alone or in combination with cisplatin did not cause accumulation of PINK1, meaning that under hypoxic conditions cells survive through activation of a receptor-mediated pathway. Hypoxia triggers the accumulation of BNIP3 and BNIP3L (also known as NIX), key participants in receptor-mediated mitophagy. Under hypoxic conditions, stimulation of autophagy, as assessed by the accumulation of lipidated form of LC3 (LC3II), was observed. To exclude the contribution of canonical macroautophagy in LC3II accumulation, experiments were performed using U1810 cells lacking ATG13, a key enzyme of macroautophagy. Despite the absence of ATG13, hypoxia-mediated accumulation of LC3II was not affected, underlying the importance of the receptor-mediated pathway. In order to prove the protective role of BNIP3 against cisplatin-induced apoptosis, BNIP3-deficient A549 cells were used. Surprisingly, a BNIP3 knockout did not abolish hypoxia-induced protection; however, in cells lacking BNIP3, a compensatory upregulation of BNIP3L was detected. Thus, in the absence of BNIP3, mitophagy could be maintained by BNIP3L and lead to cell death suppression due to the elimination of proapoptotic mitochondria. When both BNIP3 and BNIP3L were knocked out, the inhibitory effect of hypoxia on apoptosis was diminished, although not abolished completely. Undoubtedly, receptor-mediated mitophagy is likely to be one of the mechanisms responsible for cell death suppression under hypoxic conditions. MDPI 2021-08-10 /pmc/articles/PMC8394032/ /pubmed/34439183 http://dx.doi.org/10.3390/cancers13164027 Text en © 2021 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article Abdrakhmanov, Alibek Yapryntseva, Maria A. Kaminskyy, Vitaliy O. Zhivotovsky, Boris Gogvadze, Vladimir Receptor-Mediated Mitophagy Rescues Cancer Cells under Hypoxic Conditions |
title | Receptor-Mediated Mitophagy Rescues Cancer Cells under Hypoxic Conditions |
title_full | Receptor-Mediated Mitophagy Rescues Cancer Cells under Hypoxic Conditions |
title_fullStr | Receptor-Mediated Mitophagy Rescues Cancer Cells under Hypoxic Conditions |
title_full_unstemmed | Receptor-Mediated Mitophagy Rescues Cancer Cells under Hypoxic Conditions |
title_short | Receptor-Mediated Mitophagy Rescues Cancer Cells under Hypoxic Conditions |
title_sort | receptor-mediated mitophagy rescues cancer cells under hypoxic conditions |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8394032/ https://www.ncbi.nlm.nih.gov/pubmed/34439183 http://dx.doi.org/10.3390/cancers13164027 |
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