RESUMO
The p21-activated kinases (Paks) interact with Rac/Cdc42 GTPases to regulate the actin cytoskeleton as well as various signaling pathways. Although activation of Paks in many human cancers is known to mediate cancer progression, the role of Pak proteins in hypoxia is poorly understood. In this study, we found that both Pak1 and Pak4 are highly expressed in HeLa cervical cancer cells, but only Pak4 knockdown attenuates expression of hypoxia-inducible factor-1α (HIF-1α) in hypoxia. We further discovered that Pak4 regulates HIF-1α translation via the Akt-mTOR-4E-BP1 pathway under hypoxic conditions. These results support a novel connection between HIF-1α and Pak4 in hypoxic cancer cells, and provide insights into mechanisms whereby tumors respond to and thrive under oxygen-deficient conditions.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Regulação Neoplásica da Expressão Gênica , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Fosfoproteínas/genética , Proteínas Proto-Oncogênicas c-akt/genética , Serina-Treonina Quinases TOR/genética , Quinases Ativadas por p21/genética , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas de Ciclo Celular , Hipóxia Celular , Genes Reporter , Células HCT116 , Células HeLa , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Luciferases/genética , Luciferases/metabolismo , Fosfoproteínas/metabolismo , Biossíntese de Proteínas , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Serina-Treonina Quinases TOR/metabolismo , Quinases Ativadas por p21/metabolismoRESUMO
Increasing evidence emphasizes the role of the hypoxia-inducible factor (HIF) prolyl hydroxylase (PHD) isoforms in regulating non-HIF substrates, but isoform selective PHD inhibitors under physiological conditions have not yet been reported. Here we have identified pyrithione Zn (PZ) as a potent, isoform-selective PHD3 inhibitor. The IC50 value of PZ was determined as 0.98 µM for PHD3, while it did not show any inhibitory activity toward full length and truncated PHD2 up to 1 mM. The selective efficacy of PZ was further demonstrated at the cellular level by observing inhibition of the PHD3-dependent DNA damage response pathway without stabilization of HIF-1α.
Assuntos
Dano ao DNA/fisiologia , Reparo do DNA/fisiologia , Prolina Dioxigenases do Fator Induzível por Hipóxia/antagonistas & inibidores , Prolina Dioxigenases do Fator Induzível por Hipóxia/metabolismo , Compostos Organometálicos/administração & dosagem , Compostos Organometálicos/química , Piridinas/administração & dosagem , Piridinas/química , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/fisiologia , Reparo do DNA/efeitos dos fármacos , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos/métodos , Ativação Enzimática , Células HeLa , HumanosRESUMO
We report herein that Zn(II) selectively inhibits the hypoxia-inducible factor prolyl hydroxylase PHD3 over PHD2, and does not compete with Fe(II). Independent of the oligomer formation induced by Zn(II), inhibition of the activity of PHD3 by Zn(II) involves Cys42 and Cys52 residues distantly located from the active site.