EGR-1 forms a complex with YAP-1 and upregulates Bax expression in irradiated prostate carcinoma cells.
In this study, we investigated the functional role of early growth response-1 (Egr1 gene) in the regulation of radiation-induced clonogenic inhibition and apoptosis in p53 wild-type and mutant prostate cancer cells 22Rv1 and DU145, respectively. 22Rv1 cells were more sensitive to irradiation compared with DU145 cells, and the sensitivity was enhanced by overexpression of EGR-1 in both cells. Dominant-negative EGR-1 mutant (dnEGR-1) or repressor of EGR-1, NGFIA binding protein 1 (NAB1), increased radioresistance of these cells. Significant activation of caspases 3 and 9 and Bcl2-associated X (Bax) with increased poly(ADP-ribose) polymerase (PARP) cleavage and cytochrome c release was observed in radiation-exposed EGR-1 overexpressing cells. Gel shift analysis and chloramphenicol acetyl transferase (CAT) reporter assays indicate that EGR-1 transactivates the promoter of the Bax gene. Interaction of EGR-1 and Yes kinase-associated protein 1 (YAP-1) through the WW domain of YAP-1 enhances the transcriptional activity of EGR-1 on the Bax promoter as shown by chromatin immunoprecipitation and reporter assays. Irradiation of PC3 cell xenografts that were treated with adenoviral EGR-1 showed significant regression in tumor volume. These findings establish the radiation-induced pro-apoptotic action of EGR-1, in a p53-independent manner, by directly transactivating Bax, and prove that alters the B-cell CLL/lymphoma 2 (Bcl-2)/Bax ratio as one of the mechanisms resulting in significant activation of caspases, leading to cell death through the novel interaction of EGR-1 with YAP-1.
Zagurovskaya
M
M
Weis Center for Research, Geisinger Clinic, Danville, PA, USA.
Shareef
M M
MM
Das
A
A
Reeves
A
A
Gupta
S
S
Sudol
M
M
Bedford
M T
MT
Prichard
J
J
Mohiuddin
M
M
Ahmed
M M
MM
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis / Q000502:physiology / Q000528:radiation effects*; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D003114:Colony-Forming Units Assay; D045304:Cytochromes c / Q000378:metabolism; D051766:Early Growth Response Protein 1 / Q000235:genetics / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D006801:Humans; D047468:Immunoprecipitation; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D040081:Protein Array Analysis; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011836:Radiation Tolerance; D012097:Repressor Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors; D015533:Transcriptional Activation; D014162:Transfection; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured; D015854:Up-Regulation; D014965:X-Rays; D000091102:YAP-Signaling Proteins; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; C494826:BAX protein, human; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; C094815:NAB1 protein, human; D010750:Phosphoproteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D012097:Repressor Proteins; D014157:Transcription Factors; D000091102:YAP-Signaling Proteins; C088374:YAP1 protein, human; D051028:bcl-2-Associated X Protein; D045304:Cytochromes c; D015500:Chloramphenicol O-Acetyltransferase; D011065:Poly(ADP-ribose) Polymerases; D053148:Caspase 3