Interaction of HIF and USF signaling pathways in human genes flanked by hypoxia-response elements and E-box palindromes.

Abstract

Rampant activity of the hypoxia-inducible factor (HIF)-1 in cancer is frequently associated with the malignant progression into a harder-to-treat, increasingly aggressive phenotype. Clearly, anti-HIF strategies in cancer cells are of considerable clinical interest. One way to fine-tune, or inhibit, HIF's transcriptional outflow independently of hydroxylase activities could be through competing transcription factors. A CACGTG-binding activity in human hepatoma cells was previously found to restrict HIF's access to hypoxia response cis-elements (HRE) in a Daphnia globin gene promoter construct (phb2). The CACGTG factor, and its impact on hypoxia-responsive human genes, was analyzed in this study by genome-wide computational scans as well as gene-specific quantitative PCR, reporter and DNA-binding assays in hepatoma (Hep3B), cervical carcinoma (HeLa), and breast carcinoma (MCF7) cells. Among six basic helix-loop-helix transcription factors known to target CACGTG palindromes, we identified upstream stimulatory factor (USF)-1/2 as predominant phb2 CACGTG constituents in Hep3B, HeLa, and MCF7 cells. Human genes with adjacent or overlapping HRE and CACGTG motifs included with lactate dehydrogenase A (LDHA) and Bcl-2/E1B 19 kDa interacting protein 3 (BNIP3) hypoxia-induced HIF-1 targets. Parallel recruitment of HIF-1α and USF1/2a to the respective promoter chromatin was verified for all cell lines investigated. Mutual complementing (LDHA) or moderating (BNIP3) cross-talk was seen upon overexpression or silencing of HIF-1α and USF1/2a. Distinct (LDHA) or overlapping (BNIP3) promoter-binding sites for HIF-1 and USFs were subsequently characterized. We propose that, depending on abundance or activity of its protein constituents, O(2)-independent USF signaling can function to fine-tune or interfere with HIF-mediated transcription in cancer cells.

• Authors: Junmin Hu, Daniel P Stiehl, Claudia Setzer, Daniela Wichmann, Dheeraj A Shinde, Hubert Rehrauer, Pavel Hradecky, Max Gassmann, Thomas A Gorr
• Journal: Molecular cancer research : MCR (Mol Cancer Res) Vol. 9 Issue 11 Pg. 1520-36 (Nov 2011) ISSN: 1557-3125 [Electronic] United States
• PMID: 21984181 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Mol Cancer Res; 9(11); 1520-36. ©2011 AACR.

Chemical References

• Hypoxia-Inducible Factor 1
• PHB2 protein, human
• Prohibitins
• USF1 protein, human
• USF2 protein, human
• Upstream Stimulatory Factors

Topics

• Cell Line, Tumor
• E-Box Elements
• Female
• HeLa Cells
• Humans
• Hypoxia-Inducible Factor 1 (genetics, metabolism)
• Inverted Repeat Sequences
• Prohibitins
• Response Elements
• Signal Transduction
• Transfection
• Upstream Stimulatory Factors (genetics, metabolism)