Faculty Opinions recommendation of Thymosin β4 induces the expression of vascular endothelial growth factor (VEGF) in a hypoxia-inducible factor (HIF)-1α-dependent manner.

2018 ◽  
Author(s):  
David Sassoon ◽  
Mariana Valente
Keyword(s):  
Vascular Endothelial Growth Factor ◽  
Growth Factor ◽  
Hypoxia Inducible Factor ◽  
Dependent Manner ◽  
Vascular Endothelial ◽  
Thymosin Β4 ◽  
Endothelial Growth Factor

scholarly journals HER2 (neu) Signaling Increases the Rate of Hypoxia-Inducible Factor 1α (HIF-1α) Synthesis: Novel Mechanism for HIF-1-Mediated Vascular Endothelial Growth Factor Expression

2001 ◽  
Vol 21 (12) ◽  
pp. 3995-4004 ◽  
Author(s):  
Erik Laughner ◽  
Panthea Taghavi ◽  
Kelly Chiles ◽  
Patrick C. Mahon ◽  
Gregg L. Semenza
Keyword(s):  
Breast Cancer ◽  
Vascular Endothelial Growth Factor ◽  
Growth Factor ◽  
Cancer Cells ◽  
Half Life ◽  
Hypoxia Inducible Factor ◽  
Dependent Manner ◽  
Vascular Endothelial ◽  
Her2 Signaling ◽  
Endothelial Growth Factor

ABSTRACT Hypoxia-inducible factor 1 (HIF-1) is a transcriptional activator composed of HIF-1α and HIF-1β subunits. Several dozen HIF-1 targets are known, including the gene encoding vascular endothelial growth factor (VEGF). Under hypoxic conditions, HIF-1α expression increases as a result of decreased ubiquitination and degradation. The tumor suppressors VHL (von Hippel-Lindau protein) and p53 target HIF-1α for ubiquitination such that their inactivation in tumor cells increases the half-life of HIF-1α. Increased phosphatidylinositol 3-kinase (PI3K) and AKT or decreased PTEN activity in prostate cancer cells also increases HIF-1α expression by an undefined mechanism. In breast cancer, increased activity of the HER2 (also known as neu) receptor tyrosine kinase is associated with increased tumor grade, chemotherapy resistance, and decreased patient survival. HER2 has also been implicated as an inducer of VEGF expression. Here we demonstrate that HER2 signaling induced by overexpression in mouse 3T3 cells or heregulin stimulation of human MCF-7 breast cancer cells results in increased HIF-1α protein and VEGF mRNA expression that is dependent upon activity of PI3K, AKT (also known as protein kinase B), and the downstream kinase FRAP (FKBP-rapamycin-associated protein). In contrast to other inducers of HIF-1 expression, heregulin stimulation does not affect the half-life of HIF-1α but instead stimulates HIF-1α synthesis in a rapamycin-dependent manner. The 5′-untranslated region of HIF-1α mRNA directs heregulin-inducible expression of a heterologous protein. These data provide a molecular basis for VEGF induction and tumor angiogenesis by heregulin-HER2 signaling and establish a novel mechanism for the regulation of HIF-1α expression.

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