Critical roles of AMP-activated protein kinase in the carcinogenic metal-induced expression of VEGF and HIF-1 proteins in DU145 prostate carcinoma

Biochem Pharmacol. 2006 Jun 28;72(1):91-103. doi: 10.1016/j.bcp.2006.03.021. Epub 2006 Mar 30.

Abstract

Epidemiological and experimental animal data indicate that exposure to both metals and metalloid species exacerbates the risk of human diseases, particularly cancers. Vascular endothelial growth factor (VEGF), which performs a primary function in both tumor progression and angiogenesis, is up-regulated due to exposure to an array of carcinogenic metals, but the mechanisms responsible for the metal activation remain somewhat poorly understood. Recently, we demonstrated that AMP-activated protein kinase (AMPK), which acts as an energy sensor, providing metabolic adaptation effects under ATP-deprived conditions, is critical for the expression of VEGF under oxygen- and glucose-deprived conditions. As carcinogenic metals are potent VEGF expression inducers, we hypothesized that AMPK would also play a crucial role in metal-induced VEGF expression. Here, we present evidence that carcinogenic metals such as arsenite, vanadate, and cobalt, induce AMPK activation and VEGF expression via several different mechanisms, and that AMPK is able to regulate the expression of VEGF mRNA in a hypoxia-inducible factor-1-dependent or -independent manner, depending on the metal applied. We also attempted to characterize the relevant signal transduction pathways in metal-induced VEGF expression and AMPK activation, as well as the role of reactive oxygen species within this context. Overall, our data suggest that AMPK is a critical regulatory component in metal-induced VEGF expression, which further implies its intrinsic involvement in metal-induced carcinogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AMP-Activated Protein Kinases
  • Adenoviridae / genetics
  • Arsenates / toxicity
  • Carcinogens / toxicity*
  • Cell Line, Tumor / drug effects
  • Cell Line, Tumor / enzymology
  • Cell Survival
  • Cobalt / toxicity
  • Enzyme-Linked Immunosorbent Assay
  • Gene Expression Regulation, Neoplastic / drug effects*
  • Gene Transfer Techniques
  • Humans
  • Hypoxia-Inducible Factor 1 / genetics
  • Hypoxia-Inducible Factor 1 / metabolism*
  • Male
  • Metals / toxicity*
  • Multienzyme Complexes / metabolism*
  • Prostatic Neoplasms / drug therapy*
  • Prostatic Neoplasms / enzymology
  • Protein Serine-Threonine Kinases / metabolism*
  • RNA, Messenger / metabolism
  • Reactive Oxygen Species / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Vanadates / toxicity
  • Vascular Endothelial Growth Factor A / genetics
  • Vascular Endothelial Growth Factor A / metabolism*

Substances

  • Arsenates
  • Carcinogens
  • Hypoxia-Inducible Factor 1
  • Metals
  • Multienzyme Complexes
  • RNA, Messenger
  • Reactive Oxygen Species
  • VEGFA protein, human
  • Vascular Endothelial Growth Factor A
  • Cobalt
  • Vanadates
  • sodium arsenate
  • Protein Serine-Threonine Kinases
  • AMP-Activated Protein Kinases
  • cobaltous chloride