Identification of hypoxia-inducible factor-1alpha (HIF-1alpha) polymorphism as a mutation in prostate cancer that prevents normoxia-induced degradation.

BACKGROUND

Hypoxia-inducible factor-1alpha (HIF-1alpha) regulates cellular responses to hypoxia and is rapidly degraded under normoxia through von Hippel-Lindau (VHL) mediated ubiquitination. Although HIF-1alpha stabilization appears to be the molecular basis for VHL-associated cancers, stabilizing mutations in HIF-1alpha have not been reported.

METHODS

A series of 15 metastatic androgen independent prostate cancers were examined for mutations in the oxygen-dependent domain (ODD) of HIF-1alpha by PCR amplification and DNA sequencing.

RESULTS

A somatic proline to serine mutation in codon 582 (P582S) was identified in one sample. Transfection studies with a HIF-1alpha regulated reporter gene showed increased transcriptional activity that correlated with higher mutant HIF-1alpha protein expression. Increased expression of the P582S mutant induced by iron chelation, which blocks proline hydroxylation of wild-type HIF-1alpha, was markedly attenuated. The mutant also showed increased stability under normoxic versus hypoxic conditions.

CONCLUSION

The P582S HIF-1alpha is a stable variant and HIF-1alpha mutation is a mechanism for enhancing HIF-1alpha activity in human cancer. The recent identification of the identical P582S HIF-1alpha as a polymorphism suggests that this variant may increase tumor susceptibility or cause more aggressive biological behavior.