Dcr3 inhibit p53-dependent apoptosis in gamma-irradiated lung cancer cells.
OBJECTIVE
To identify genes responsible for the radiosensitivity, we investigated the role of the differential gene expression profiles by comparing radioresistant H1299 with radiosensitive H460 lung cancer cell lines.


METHODS
mRNA profiles of lung cancer cell lines were assessed using microarray, and subsequent validation was performed with qRT-PCR (Quantitative real time-polymerase chain reaction). The expression levels of differentially expressed genes were determined by Western blot and the radioresistance of lung cancer cell lines was measured by clonogenic assay.


RESULTS
From the differentially expressed apoptosis-related genes between H1299 and H460, we found Dcr3 (Decoy receptor 3, also known as TNFRSF6B; Tumour necrosis factor receptor super family member 6B) expression was significantly (P = 4.38 x 10(-7)) higher in H1299 cells than H460 cells. Moreover, the Dcr3 mRNA expression level in the radioresistant cell lines (H1299, A549, DLD1, MB231, MB157) was increased in comparison to the radiosensitive cell lines (ME180, Caski, U87MG, MCF7, H460). Overexpression of Dcr3 increased the survival rate of radiosensitive H460, MCF7, and U87MG cells, and knockdown of Dcr3 abolished the radioresistance of A549 cells. The survival rate of p53 (Tumour protein 53)-deficient H1299 after gamma-irradiation was not affected by the suppression of Dcr3 expression. However, when we introduced p53 into H1299 cells, siDcr3 (siRNA of Dcr3) suppressed the radioresistance of H1299 cells by inducing p53-dependent Fas (Fas receptor, also known as TNFRSF6; Tumour necrosis factor receptor super family member 6)-mediated apoptosis pathway.


CONCLUSIONS
Characterisation of gene expression profiles in two lung cancer cell lines revealed that Dcr3 expression and p53-dependent apoptosis signalling pathway regulate cellular response to ionising radiation.
Sung
Hye Youn
HY
Department of Biomedical Sciences, Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul, Korea.
Wu
Hong-Gyun
HG
Ahn
Jung-Hyuck
JH
Park
Woong-Yang
WY
D017209:Apoptosis; D053181:Caspase 8 / Q000502:physiology; D045744:Cell Line, Tumor; D005720:Gamma Rays; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D012333:RNA, Messenger / Q000032:analysis; D011836:Radiation Tolerance; D053323:Receptors, Tumor Necrosis Factor, Member 6b / Q000235:genetics / Q000502:physiology*; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000502:physiology; D016159:Tumor Suppressor Protein p53 / Q000502:physiology*
D012333:RNA, Messenger; D053323:Receptors, Tumor Necrosis Factor, Member 6b; D053221:TNF-Related Apoptosis-Inducing Ligand; C505911:TNFRSF6B protein, human; C505653:TNFSF10 protein, human; D016159:Tumor Suppressor Protein p53; D053181:Caspase 8