Radiation induces autophagic cell death via the p53/DRAM signaling pathway in breast cancer cells.
Autophagy is known to play a role in the response of breast cancer cells to radiation therapy. However, the mechanisms that mediate the process of autophagy and contribute to radiation-induced cell death and cell survival remain to be fully characterized. Therefore, in this study, the functional role of autophagy in radiation-induced cytotoxicity in breast cancer cells was investigated. After MCF-7 cells were exposed to various doses of radiation, increased monodansylcadaverine (MDC) staining and a greater deposition of LC3-positive puncta were observed. Expression of the autophagy-related proteins, Beclin 1 and LC3-II, were also found to be upregulated. Radiation-induced autophagic cell death was partially abrogated following the administration of 3-methyladenine (3-MA) and in knockdown experiments of Atg5 and Beclin 1. In the gene microarray analysis performed after irradiation, a number of differentially expressed genes were identified. In particular, upregulation of both the mRNA and protein levels of the autophagy-related genes, DRAM and TIGAR, were detected. However, inhibition of autophagy by 3-MA reduced the radiation-induced upregulation of LC3-II and DRAM. Conversely, silencing of p53 downregulated the expression of LC3-II and DRAM following radiation. Silencing of DRAM reversed the upregulation of LC3-II and DRAM following radiation, partially blocked radiation-induced cell death, and no significant change in p53 expression was detected. Based on these results, the p53/DRAM signaling pathway appears to contribute to radiation-induced autophagic cell death in MCF-7 breast cancer cells.
Key Laboratory of Radiobiology (Ministry of Health), School of Public Health, Jilin University, Changchun, Jilin 130021, P.R. China.
Li
L
Cui
Jilin Province People's Hospital, Changchun, Jilin 130021, P.R. China.
Zhiheng
Z
Song
Key Laboratory of Radiobiology (Ministry of Health), School of Public Health, Jilin University, Changchun, Jilin 130021, P.R. China.
Bing
B
Liang
Key Laboratory of Radiobiology (Ministry of Health), School of Public Health, Jilin University, Changchun, Jilin 130021, P.R. China.
Lili
L
Jia
Key Laboratory of Radiobiology (Ministry of Health), School of Public Health, Jilin University, Changchun, Jilin 130021, P.R. China.
Shumei
S
Ma
Key Laboratory of Radiobiology (Ministry of Health), School of Public Health, Jilin University, Changchun, Jilin 130021, P.R. China.
Xiaodong
X
Liu
D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D017209:Apoptosis / Q000528:radiation effects*; D051017:Apoptosis Regulatory Proteins; D001343:Autophagy / Q000187:drug effects / Q000528:radiation effects*; D000071187:Autophagy-Related Protein 5 / Q000235:genetics / Q000378:metabolism; D000071186:Beclin-1 / Q000235:genetics / Q000378:metabolism; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000528:radiation effects; D015536:Down-Regulation; D005260:Female; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D061986:MCF-7 Cells; D008565:Membrane Proteins / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D010744:Phosphoric Monoester Hydrolases; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D011839:Radiation, Ionizing; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D015854:Up-Regulation
C502778:ATG5 protein, human; D051017:Apoptosis Regulatory Proteins; D000071187:Autophagy-Related Protein 5; C491997:BECN1 protein, human; D000071186:Beclin-1; C512709:DRAM1 protein, human; D047908:Intracellular Signaling Peptides and Proteins; C477012:MAP1LC3A protein, human; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; D034741:RNA, Small Interfering; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; C025946:3-methyladenine; D010744:Phosphoric Monoester Hydrolases; C512708:TIGAR protein, human; D000225:Adenine