Cargando…

Radiation-Induced Autophagy Contributes to Cell Death and Induces Apoptosis Partly in Malignant Glioma Cells

PURPOSE: Radiation-induced autophagy has been shown to play two different roles, in malignant glioma (MG) cells, cytocidal or cytoprotective. However, neither the role of radiation-induced autophagy for cell death nor the existence of autophagy-induced apoptosis, a well-known cell-death pathway afte...

Descripción completa

Detalles Bibliográficos
Autores principales: Jo, Guk Heui, Bögler, Oliver, Chwae, Yong-Joon, Yoo, Heon, Lee, Seung Hoon, Park, Jong Bae, Kim, Youn-Jae, Kim, Jong Heon, Gwak, Ho-Shin
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Korean Cancer Association 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4398101/
https://www.ncbi.nlm.nih.gov/pubmed/25410762
http://dx.doi.org/10.4143/crt.2013.159
_version_ 1782366783196364800
author Jo, Guk Heui
Bögler, Oliver
Chwae, Yong-Joon
Yoo, Heon
Lee, Seung Hoon
Park, Jong Bae
Kim, Youn-Jae
Kim, Jong Heon
Gwak, Ho-Shin
author_facet Jo, Guk Heui
Bögler, Oliver
Chwae, Yong-Joon
Yoo, Heon
Lee, Seung Hoon
Park, Jong Bae
Kim, Youn-Jae
Kim, Jong Heon
Gwak, Ho-Shin
author_sort Jo, Guk Heui
collection PubMed
description PURPOSE: Radiation-induced autophagy has been shown to play two different roles, in malignant glioma (MG) cells, cytocidal or cytoprotective. However, neither the role of radiation-induced autophagy for cell death nor the existence of autophagy-induced apoptosis, a well-known cell-death pathway after irradiation, has been verified yet. MATERIALS AND METHODS: We observed both temporal and dose-dependent response patterns of autophagy and apoptosis to radiation in MG cell lines. Additionally, we investigated the role of autophagy in apoptosis through knockdown of autophagy-related proteins. RESULTS: Autophagic activity measured by staining of acidic vesicle organelles and Western blotting of LC-3 protein increased in proportion to radiation dose from day 1 to 5 after irradiation. Apoptosis measured by annexin-V staining and Western blotting of cleaved poly(ADP-ribose) polymerase demonstrated relatively late appearance 3 days after irradiation that increased for up to 7 days. Blocking of pan-caspase (Z-VAD-FMK) did not affect apoptosis after irradiation, but silencing of Atg5 effectively reduced radiation-induced autophagy, which decreased apoptosis significantly. Inhibition of autophagy in Atg5 knockdown cells was shown to be beneficial for cell survival. Stable transfection of GFP-LC3 cells was observed after irradiation. Annexin-V was localized in cells bearing GFP-LC3 punctuated spots, indicating autophagy in immunofluorescence. Some of these punctuated GFP-LC3 bearing cells formed conglomerated spots and died in final phase. CONCLUSION: These findings suggest that autophagy appears earlier than apoptosis after irradiation and that a portion of the apoptotic population that appears later is autophagy-dependent. Thus, autophagy is a pathway to cell death after irradiation of MG cells.
format Online
Article
Text
id pubmed-4398101
institution National Center for Biotechnology Information
language English
publishDate 2015
publisher Korean Cancer Association
record_format MEDLINE/PubMed
spelling pubmed-43981012015-04-16 Radiation-Induced Autophagy Contributes to Cell Death and Induces Apoptosis Partly in Malignant Glioma Cells Jo, Guk Heui Bögler, Oliver Chwae, Yong-Joon Yoo, Heon Lee, Seung Hoon Park, Jong Bae Kim, Youn-Jae Kim, Jong Heon Gwak, Ho-Shin Cancer Res Treat Original Article PURPOSE: Radiation-induced autophagy has been shown to play two different roles, in malignant glioma (MG) cells, cytocidal or cytoprotective. However, neither the role of radiation-induced autophagy for cell death nor the existence of autophagy-induced apoptosis, a well-known cell-death pathway after irradiation, has been verified yet. MATERIALS AND METHODS: We observed both temporal and dose-dependent response patterns of autophagy and apoptosis to radiation in MG cell lines. Additionally, we investigated the role of autophagy in apoptosis through knockdown of autophagy-related proteins. RESULTS: Autophagic activity measured by staining of acidic vesicle organelles and Western blotting of LC-3 protein increased in proportion to radiation dose from day 1 to 5 after irradiation. Apoptosis measured by annexin-V staining and Western blotting of cleaved poly(ADP-ribose) polymerase demonstrated relatively late appearance 3 days after irradiation that increased for up to 7 days. Blocking of pan-caspase (Z-VAD-FMK) did not affect apoptosis after irradiation, but silencing of Atg5 effectively reduced radiation-induced autophagy, which decreased apoptosis significantly. Inhibition of autophagy in Atg5 knockdown cells was shown to be beneficial for cell survival. Stable transfection of GFP-LC3 cells was observed after irradiation. Annexin-V was localized in cells bearing GFP-LC3 punctuated spots, indicating autophagy in immunofluorescence. Some of these punctuated GFP-LC3 bearing cells formed conglomerated spots and died in final phase. CONCLUSION: These findings suggest that autophagy appears earlier than apoptosis after irradiation and that a portion of the apoptotic population that appears later is autophagy-dependent. Thus, autophagy is a pathway to cell death after irradiation of MG cells. Korean Cancer Association 2015-04 2014-08-29 /pmc/articles/PMC4398101/ /pubmed/25410762 http://dx.doi.org/10.4143/crt.2013.159 Text en Copyright © 2015 by the Korean Cancer Association This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/)which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Original Article
Jo, Guk Heui
Bögler, Oliver
Chwae, Yong-Joon
Yoo, Heon
Lee, Seung Hoon
Park, Jong Bae
Kim, Youn-Jae
Kim, Jong Heon
Gwak, Ho-Shin
Radiation-Induced Autophagy Contributes to Cell Death and Induces Apoptosis Partly in Malignant Glioma Cells
title Radiation-Induced Autophagy Contributes to Cell Death and Induces Apoptosis Partly in Malignant Glioma Cells
title_full Radiation-Induced Autophagy Contributes to Cell Death and Induces Apoptosis Partly in Malignant Glioma Cells
title_fullStr Radiation-Induced Autophagy Contributes to Cell Death and Induces Apoptosis Partly in Malignant Glioma Cells
title_full_unstemmed Radiation-Induced Autophagy Contributes to Cell Death and Induces Apoptosis Partly in Malignant Glioma Cells
title_short Radiation-Induced Autophagy Contributes to Cell Death and Induces Apoptosis Partly in Malignant Glioma Cells
title_sort radiation-induced autophagy contributes to cell death and induces apoptosis partly in malignant glioma cells
topic Original Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4398101/
https://www.ncbi.nlm.nih.gov/pubmed/25410762
http://dx.doi.org/10.4143/crt.2013.159
work_keys_str_mv AT jogukheui radiationinducedautophagycontributestocelldeathandinducesapoptosispartlyinmalignantgliomacells
AT bogleroliver radiationinducedautophagycontributestocelldeathandinducesapoptosispartlyinmalignantgliomacells
AT chwaeyongjoon radiationinducedautophagycontributestocelldeathandinducesapoptosispartlyinmalignantgliomacells
AT yooheon radiationinducedautophagycontributestocelldeathandinducesapoptosispartlyinmalignantgliomacells
AT leeseunghoon radiationinducedautophagycontributestocelldeathandinducesapoptosispartlyinmalignantgliomacells
AT parkjongbae radiationinducedautophagycontributestocelldeathandinducesapoptosispartlyinmalignantgliomacells
AT kimyounjae radiationinducedautophagycontributestocelldeathandinducesapoptosispartlyinmalignantgliomacells
AT kimjongheon radiationinducedautophagycontributestocelldeathandinducesapoptosispartlyinmalignantgliomacells
AT gwakhoshin radiationinducedautophagycontributestocelldeathandinducesapoptosispartlyinmalignantgliomacells