Hypoxia-inducible factor 1{alpha} is a new target of microphthalmia-associated transcription factor (MITF) in melanoma cells

J Cell Biol. 2005 Jul 4;170(1):49-59. doi: 10.1083/jcb.200501067. Epub 2005 Jun 27.

Abstract

In melanocytes and melanoma cells alpha-melanocyte stimulating hormone (alpha-MSH), via the cAMP pathway, elicits a large array of biological responses that control melanocyte differentiation and influence melanoma development or susceptibility. In this work, we show that cAMP transcriptionally activates Hif1a gene in a melanocyte cell-specific manner and increases the expression of a functional hypoxia-inducible factor 1alpha (HIF1alpha) protein resulting in a stimulation of Vegf expression. Interestingly, we report that the melanocyte-specific transcription factor, microphthalmia-associated transcription factor (MITF), binds to the Hif1a promoter and strongly stimulates its transcriptional activity. Further, MITF "silencing" abrogates the cAMP effect on Hif1a expression, and overexpression of MITF in human melanoma cells is sufficient to stimulate HIF1A mRNA. Our data demonstrate that Hif1a is a new MITF target gene and that MITF mediates the cAMP stimulation of Hif1a in melanocytes and melanoma cells. Importantly, we provide results demonstrating that HIF1 plays a pro-survival role in this cell system. We therefore conclude that the alpha-MSH/cAMP pathway, using MITF as a signal transducer and HIF1alpha as a target, might contribute to melanoma progression.

MeSH terms

  • Animals
  • Cell Survival / drug effects
  • Cell Survival / physiology
  • Cyclic AMP / metabolism
  • Cyclic AMP / pharmacology
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Disease Progression
  • Gene Expression Regulation, Neoplastic / genetics
  • Genes, Regulator / genetics
  • Humans
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Melanocytes / cytology
  • Melanocytes / drug effects
  • Melanocytes / metabolism*
  • Melanoma / genetics
  • Melanoma / metabolism*
  • Mice
  • Microphthalmia-Associated Transcription Factor
  • NIH 3T3 Cells
  • Promoter Regions, Genetic / physiology
  • RNA Interference / drug effects
  • RNA Interference / physiology
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Signal Transduction / physiology
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Transcriptional Activation / drug effects
  • Transcriptional Activation / physiology
  • Tumor Cells, Cultured
  • Vascular Endothelial Growth Factor A / genetics
  • alpha-MSH / metabolism

Substances

  • DNA-Binding Proteins
  • HIF1A protein, human
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • MITF protein, human
  • Microphthalmia-Associated Transcription Factor
  • Mitf protein, mouse
  • RNA, Messenger
  • Transcription Factors
  • Vascular Endothelial Growth Factor A
  • alpha-MSH
  • Cyclic AMP