Differential expression of antiapoptotic gene BAG-1 in human breast normal and cancer cell lines and tissues.
BAG-1 is an antiapoptotic protein that binds to and enhances the antiapoptotic activity of Bcl-2. It binds several growth factor and hormone receptors and modulates their function. BAG-1 was also shown recently to be expressed as four protein isoforms, p50, p46, p33, and p29, through alternative translation initiation. Although many apoptosis-associated genes have been linked to oncogenesis of human breast cancer, the role of BAG-1 has not been fully elucidated. In this study, we examined the expression of BAG-1 RNA or protein isoforms and its interacting antiapoptotic proteins, Bcl-2 and BcI-X(L), in breast normal and tumor cell lines and tissues by Northern or Western blot analysis. We provide convincing evidence that both BAG-1 RNA and protein are overexpressed in human breast cancer cell lines. More importantly, we found that the expression of two isoforms of BAG-1, p46 and p33, was also much higher in breast primary tumors. The expression of Bcl-2 and Bcl-X(L) correlated with that of BAG-1 in breast normal and carcinoma cell lines but not tissues. Our study suggests that BAG-1 isoforms may serve as a molecular marker, independent of Bcl-2 and Bcl-X(L), for human breast cancer.
Yang
X
X
Basic Medical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Canada.
Hao
Y
Y
Ding
Z
Z
Pater
A
A
Tang
S C
SC
D000230:Adenocarcinoma / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000096:biosynthesis; D001940:Breast / Q000378:metabolism*; D001943:Breast Neoplasms / Q000378:metabolism*; D018270:Carcinoma, Ductal, Breast / Q000378:metabolism; D002352:Carrier Proteins / Q000096:biosynthesis*; D002478:Cells, Cultured; D004268:DNA-Binding Proteins; D006801:Humans; D020033:Protein Isoforms / Q000096:biosynthesis; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D014157:Transcription Factors; D014407:Tumor Cells, Cultured; D051020:bcl-X Protein
C091732:BCL2-associated athanogene 1 protein; C494811:BCL2L1 protein, human; D014408:Biomarkers, Tumor; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D020033:Protein Isoforms; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D014157:Transcription Factors; D051020:bcl-X Protein