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3′-epi-12β-hydroxyfroside, a new cardenolide, induces cytoprotective autophagy via blocking the Hsp90/Akt/mTOR axis in lung cancer cells
Rationale: Cardenolides have potential as anticancer drugs. 3′-epi-12β-hydroxyfroside (HyFS) is a new cardenolide structure isolated by our research group, but its molecular mechanisms remain poorly understood. This study investigates the relationship between its antitumor activities and autophagy i...
Autores principales: | , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Ivyspring International Publisher
2018
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5858516/ https://www.ncbi.nlm.nih.gov/pubmed/29556372 http://dx.doi.org/10.7150/thno.23304 |
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author | Sun, Yan Huang, Yong-Hao Huang, Feng-Ying Mei, Wen-Li Liu, Quan Wang, Cai-Chun Lin, Ying-Ying Huang, Canhua Li, Yue-Nan Dai, Hao-Fu Tan, Guang-Hong |
author_facet | Sun, Yan Huang, Yong-Hao Huang, Feng-Ying Mei, Wen-Li Liu, Quan Wang, Cai-Chun Lin, Ying-Ying Huang, Canhua Li, Yue-Nan Dai, Hao-Fu Tan, Guang-Hong |
author_sort | Sun, Yan |
collection | PubMed |
description | Rationale: Cardenolides have potential as anticancer drugs. 3′-epi-12β-hydroxyfroside (HyFS) is a new cardenolide structure isolated by our research group, but its molecular mechanisms remain poorly understood. This study investigates the relationship between its antitumor activities and autophagy in lung cancer cells. Methods: Cell growth and proliferation were detected by MTT, lactate dehydrogenase (LDH) release, 5-ethynyl-20-deoxyuridine (EDU) and colony formation assays. Cell apoptosis was detected by flow cytometry. Autophagic and signal proteins were detected by Western blotting. Markers of autophagy and autophagy flux were also detected by immunofluorescence, transmission electron microscopy and acridine orange staining. Real time RT-PCR was used to analyze the gene expression of Hsp90. Hsp90 ubiquitination was detected by coimmunoprecipitation. The antitumore activities of HyFS were observed in nude mice. Results: HyFS treatment inhibited cell proliferation and induced autophagy in A549 and H460 lung cancer cells, but stronger inhibition of cell proliferation and induction of cell apoptosis were shown when HyFS-mediated autophagy was blocked. The Hsp90/Akt/mTOR axis was found to be involved in the activation of HyFS-mediated autophagy. Evidence of direct interaction between Hsp90 and Akt was observed. HyFS treatment resulted in decreased levels of heat shock protein 90 (Hsp90) and phosphorylated Akt, overexpression of Hsp90 increased activation of autophagy, and inhibition of Hsp90 expression decreased autophagy. In addition, ubiquitin-mediated degradation of Hsp90 and subsequent dephosphorylation of its client protein Akt were also found in HyFS-treated lung cancer cells. Moreover, combination treatment with HyFS and chloroquine showed remarkably increased tumor inhibition in both A549- and H460-bearing mice. Conclusion: Our results demonstrate that HyFS induced cytoprotective autophagy through ubiquitin-mediated degradation of Hsp90, which further blocked the Akt/mTOR pathway in lung cancer cells. Thus, a combination of a HyFS-like cardenolide and an autophagic inhibitor is a potential alternative approach for the treatment of lung cancer. |
format | Online Article Text |
id | pubmed-5858516 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2018 |
publisher | Ivyspring International Publisher |
record_format | MEDLINE/PubMed |
spelling | pubmed-58585162018-03-19 3′-epi-12β-hydroxyfroside, a new cardenolide, induces cytoprotective autophagy via blocking the Hsp90/Akt/mTOR axis in lung cancer cells Sun, Yan Huang, Yong-Hao Huang, Feng-Ying Mei, Wen-Li Liu, Quan Wang, Cai-Chun Lin, Ying-Ying Huang, Canhua Li, Yue-Nan Dai, Hao-Fu Tan, Guang-Hong Theranostics Research Paper Rationale: Cardenolides have potential as anticancer drugs. 3′-epi-12β-hydroxyfroside (HyFS) is a new cardenolide structure isolated by our research group, but its molecular mechanisms remain poorly understood. This study investigates the relationship between its antitumor activities and autophagy in lung cancer cells. Methods: Cell growth and proliferation were detected by MTT, lactate dehydrogenase (LDH) release, 5-ethynyl-20-deoxyuridine (EDU) and colony formation assays. Cell apoptosis was detected by flow cytometry. Autophagic and signal proteins were detected by Western blotting. Markers of autophagy and autophagy flux were also detected by immunofluorescence, transmission electron microscopy and acridine orange staining. Real time RT-PCR was used to analyze the gene expression of Hsp90. Hsp90 ubiquitination was detected by coimmunoprecipitation. The antitumore activities of HyFS were observed in nude mice. Results: HyFS treatment inhibited cell proliferation and induced autophagy in A549 and H460 lung cancer cells, but stronger inhibition of cell proliferation and induction of cell apoptosis were shown when HyFS-mediated autophagy was blocked. The Hsp90/Akt/mTOR axis was found to be involved in the activation of HyFS-mediated autophagy. Evidence of direct interaction between Hsp90 and Akt was observed. HyFS treatment resulted in decreased levels of heat shock protein 90 (Hsp90) and phosphorylated Akt, overexpression of Hsp90 increased activation of autophagy, and inhibition of Hsp90 expression decreased autophagy. In addition, ubiquitin-mediated degradation of Hsp90 and subsequent dephosphorylation of its client protein Akt were also found in HyFS-treated lung cancer cells. Moreover, combination treatment with HyFS and chloroquine showed remarkably increased tumor inhibition in both A549- and H460-bearing mice. Conclusion: Our results demonstrate that HyFS induced cytoprotective autophagy through ubiquitin-mediated degradation of Hsp90, which further blocked the Akt/mTOR pathway in lung cancer cells. Thus, a combination of a HyFS-like cardenolide and an autophagic inhibitor is a potential alternative approach for the treatment of lung cancer. Ivyspring International Publisher 2018-02-15 /pmc/articles/PMC5858516/ /pubmed/29556372 http://dx.doi.org/10.7150/thno.23304 Text en © Ivyspring International Publisher This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY-NC) license (https://creativecommons.org/licenses/by-nc/4.0/). See http://ivyspring.com/terms for full terms and conditions. |
spellingShingle | Research Paper Sun, Yan Huang, Yong-Hao Huang, Feng-Ying Mei, Wen-Li Liu, Quan Wang, Cai-Chun Lin, Ying-Ying Huang, Canhua Li, Yue-Nan Dai, Hao-Fu Tan, Guang-Hong 3′-epi-12β-hydroxyfroside, a new cardenolide, induces cytoprotective autophagy via blocking the Hsp90/Akt/mTOR axis in lung cancer cells |
title | 3′-epi-12β-hydroxyfroside, a new cardenolide, induces cytoprotective autophagy via blocking the Hsp90/Akt/mTOR axis in lung cancer cells |
title_full | 3′-epi-12β-hydroxyfroside, a new cardenolide, induces cytoprotective autophagy via blocking the Hsp90/Akt/mTOR axis in lung cancer cells |
title_fullStr | 3′-epi-12β-hydroxyfroside, a new cardenolide, induces cytoprotective autophagy via blocking the Hsp90/Akt/mTOR axis in lung cancer cells |
title_full_unstemmed | 3′-epi-12β-hydroxyfroside, a new cardenolide, induces cytoprotective autophagy via blocking the Hsp90/Akt/mTOR axis in lung cancer cells |
title_short | 3′-epi-12β-hydroxyfroside, a new cardenolide, induces cytoprotective autophagy via blocking the Hsp90/Akt/mTOR axis in lung cancer cells |
title_sort | 3′-epi-12β-hydroxyfroside, a new cardenolide, induces cytoprotective autophagy via blocking the hsp90/akt/mtor axis in lung cancer cells |
topic | Research Paper |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5858516/ https://www.ncbi.nlm.nih.gov/pubmed/29556372 http://dx.doi.org/10.7150/thno.23304 |
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