Loss of epigenetic Kruppel-like factor 4 histone deacetylase (KLF-4-HDAC)-mediated transcriptional suppression is crucial in increasing vascular endothelial growth factor (VEGF) expression in breast cancer.
Vascular endothelial growth factor (VEGF) is recognized as an important angiogenic factor that promotes angiogenesis in a series of pathological conditions, including cancer, inflammation, and ischemic disorders. We have recently shown that the inflammatory transcription factor SAF-1 is, at least in part, responsible for the marked increase of VEGF levels in breast cancer. Here, we show that SAF-1-mediated induction of VEGF is repressed by KLF-4 transcription factor. KLF-4 is abundantly present in normal breast epithelial cells, but its level is considerably reduced in breast cancer cells and clinical cancer tissues. In the human VEGF promoter, SAF-1- and KLF-4-binding elements are overlapping, whereas SAF-1 induces and KLF-4 suppresses VEGF expression. Ectopic overexpression of KLF-4 and RNAi-mediated inhibition of endogenous KLF-4 supported the role of KLF-4 as a transcriptional repressor of VEGF and an inhibitor of angiogenesis in breast cancer cells. We show that KLF-4 recruits histone deacetylases (HDACs) -2 and -3 at the VEGF promoter. Chronological ChIP assays demonstrated the occupancy of KLF-4, HDAC2, and HDAC3 in the VEGF promoter in normal MCF-10A cells but not in MDA-MB-231 cancer cells. Co-transfection of KLF-4 and HDAC expression plasmids in breast cancer cells results in synergistic repression of VEGF expression and inhibition of angiogenic potential of these carcinoma cells. Together these results identify a new mechanism of VEGF up-regulation in cancer that involves concomitant loss of KLF-4-HDAC-mediated transcriptional repression and active recruitment of SAF-1-mediated transcriptional activation.
Department of Veterinary Pathobiology, University of Missouri, Columbia, Missouri 65211. Electronic address: rayal@missouri.edu.
Alpana
A
Ray
Department of Veterinary Pathobiology, University of Missouri, Columbia, Missouri 65211.
Mohamed
M
Alalem
Department of Veterinary Pathobiology, University of Missouri, Columbia, Missouri 65211. Electronic address: rayb@missouri.edu.
Bimal K
BK
Ray
D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D044127:Epigenesis, Genetic; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D056464:Histone Deacetylase 2 / Q000096:biosynthesis* / Q000235:genetics; D006655:Histone Deacetylases / Q000096:biosynthesis* / Q000235:genetics; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000096:biosynthesis* / Q000235:genetics; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000096:biosynthesis* / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis* / Q000235:genetics; D000099186:Histone Deacetylase 3
D004268:DNA-Binding Proteins; D056464:Histone Deacetylase 2; D006655:Histone Deacetylases; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; D009363:Neoplasm Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; D000099186:Histone Deacetylase 3; C000715467:KLF4 protein, human; C467484:VEGFA protein, human; C076035:c-MYC-associated zinc finger protein; C533423:HDAC2 protein, human
Angiogenesis; Breast Cancer; DNA-Protein Interaction; Gene Regulation; Transcription Factors