TAp73 opposes tumor angiogenesis by promoting hypoxia-inducible factor 1α degradation

Tumor hypoxia and hypoxia-inducible factor 1 (HIF-1) activationare associated with cancer progression. Here, we demonstrate thatthe transcription factor TAp73 opposes HIF-1 activity through anontranscriptional mechanism, thus affecting tumor angiogenesis.TAp73-deficient mice have an increased incidence of spontaneousand chemically induced tumors that also display enhanced vascularization.Mechanistically, TAp73 interacts with the regulatory subunit(α) of HIF-1 and recruits mouse double minute 2 homolog intothe protein complex, thus promoting HIF-1α polyubiquitination andconsequent proteasomal degradation in an oxygen-independentmanner. In human lung cancer datasets, TAp73 strongly predictsgood patient prognosis, and its expression is associated with lowHIF-1 activation and angiogenesis. Our findings, supported by invivo and clinical evidence, demonstrate a mechanism for oxygenindependentHIF-1 regulation, which has important implicationsfor individualizing therapies in patients with cancer.