Regulation of Rad51 promoter.
The DNA double-strand break repair and homologous recombination protein Rad51 is overexpressed in the majority of human cancers. This correlates with therapy resistance and decreased patient survival. We previously showed that constructs containing Rad51 promoter fused to a reporter gene are, on average, 850-fold more active in cancer cells than in normal cells. It is not well understood what factors and sequences regulate the Rad51 promoter and cause its high activity in cancerous cells. Here we characterized regulatory regions and examined genetic requirements for oncogenic stimulation of the Rad51 promoter. We identified specific regions responsible for up- and downregulation of the Rad51 promoter in cancerous cells. Furthermore, we show that Rad51 expression is positively regulated by EGR1 transcription factor. We then modeled the malignant transformation process by expressing a set of oncoproteins in normal human fibroblasts. Expression of different combinations of SV40 large T antigen, oncogenic Ras and SV40 small T antigen resulted in step-wise increase in Rad51 promoter activity, with all the 3 oncoproteins together leading to a 47-fold increase in expression. Cumulatively, these results suggest that Rad51 promoter is regulated by multiple factors, and that its expression is gradually activated as cells progress toward malignancy.
Department of Biology; University of Rochester; Rochester, NY USA.
Christopher M
CM
Hine
Department of Biology; University of Rochester; Rochester, NY USA.
Hongjie
H
Li
Department of Biology; University of Rochester; Rochester, NY USA.
Li
L
Xie
Department of Biology; University of Rochester; Rochester, NY USA.
Zhiyong
Z
Mao
Department of Biology; University of Rochester; Rochester, NY USA.
Andrei
A
Seluanov
Department of Biology; University of Rochester; Rochester, NY USA.
Vera
V
Gorbunova
D000952:Antigens, Polyomavirus Transforming / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D011401:Promoter Regions, Genetic; D051135:Rad51 Recombinase / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism; D015854:Up-Regulation; D018631:ras Proteins / Q000378:metabolism
D000952:Antigens, Polyomavirus Transforming; C094815:NAB1 protein, human; D012097:Repressor Proteins; D051135:Rad51 Recombinase; D018631:ras Proteins
DNA repair; EGR1; Rad51 promoter; cancer; p53; therapy resistance