Somatic mutation and functional polymorphism of a novel regulatory element in the HGF gene promoter causes its aberrant expression in human breast cancer
Jihong Ma, … , Robert Ferrell, Reza Zarnegar
Jihong Ma, … , Robert Ferrell, Reza Zarnegar
Published February 2, 2009
Citation Information: J Clin Invest. 2009;119(3):478-491. https://doi.org/10.1172/JCI36640.
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Research Article Oncology

Somatic mutation and functional polymorphism of a novel regulatory element in the HGF gene promoter causes its aberrant expression in human breast cancer

Abstract

The HGF gene is transcriptionally silenced in normal differentiated breast epithelial cells, but its repression fails to occur in mammary carcinoma tissues and cell lines. The molecular mechanisms underpinning aberrant HGF expression in breast cancer cells are unknown. Here we report the discovery of a DNA element located 750 bp upstream from the transcription start site in the human HGF promoter that acts as a transcriptional repressor and is a target of deletion mutagenesis in human breast cancer cells and tissues. This HGF promoter element consists of a mononucleotide repeat of 30 deoxyadenosines (30As), which we have termed “deoxyadenosine tract element” (DATE). Functional studies revealed that truncation mutations within DATE have profound local and global effects on the HGF promoter region by modulating chromatin structure and DNA-protein interactions, leading to constitutive activation of the HGF promoter in human breast carcinoma cell lines. We found that 51% of African Americans and 15% of individuals of mixed European descent with breast cancer harbor a truncated DATE variant (25As or fewer) in their breast tumors and that the truncated allele is associated with cancer incidence and aberrant HGF expression. Notably, breast cancer patients with the truncated DATE variant are substantially younger than those with a wild-type genotype. We also suggest that DATE may be used as a potential genetic marker to identify individuals with a higher risk of developing breast cancer.

Authors

Jihong Ma, Marie C. DeFrances, Chunbin Zou, Carla Johnson, Robert Ferrell, Reza Zarnegar

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Figure 2

Regulatory effects of DATE on HGF promoter activity.

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Regulatory effects of DATE on HGF promoter activity. (A) Schematic r...
(A) Schematic representation of pHGF–luciferase reporter plasmids. HGF promoter region (1.1 kb; –1,037 to +56) containing wild-type (30As) or shortened DATE (29As, 28As, 27As, 26As, 25As, 20As, and 14As) from normal and different breast cancer tissues, respectively, were inserted upstream of the luciferase report gene in pGL2-basic vector and were termed pHGF30A-Luc, pHGF29A-Luc, pHGF28A-Luc, pHGF27A-Luc, pHGF26A-Luc, pHGF25A-Luc, pHGF20A-Luc, and HGF14A-Luc. pGL2-basic (basic-Luc) was used as negative control vector. (B) Luciferase activity profile. The above constructs along with pRL-TK as an internal control vector were transiently transfected into HeLa cells as indicated in the figure. As depicted, luciferase activity in pHGF30A-Luc was significantly lower than those constructs with truncated DATE (30As vs. 14As, P = 0.0006; 30As vs. 20As, P = 0.0016; 30As vs. 25As, P = 0.0025). **P < 0.01, ***P < 0.001 compared with pHGF30A-Luc.