PHD4 stimulates tumor angiogenesis in osteosarcoma cells via TGF-α.

Unlabelled: Solid tumor growth is intimately associated with angiogenesis, a process that is efficiently triggered by hypoxia. Therefore, oxygen-sensitive signaling pathways are thought to play a critical role in tumor angiogenesis and progression. Here, the function of prolyl hydroxylase-4 (PHD4), a relative of the prolyl hydroxylase domain proteins 1-3 that promote the degradation of hypoxia-inducible factors (HIF), was interrogated.

Interplay between neural-cadherin and vascular endothelial-cadherin in breast cancer progression.

Introduction: Deregulation of cadherin expression, in particular the loss of epithelial (E)-cadherin and gain of neural (N)-cadherin, has been implicated in carcinoma progression. We previously showed that endothelial cell-specific vascular endothelial (VE)-cadherin can be expressed aberrantly on tumor cells both in human breast cancer and in experimental mouse mammary carcinoma. Functional analyses revealed that VE-cadherin promotes tumor cell proliferation and invasion by stimulating transforming growth factor (TGF)-β signaling.

Overexpression of factor inhibiting HIF-1 enhances vessel maturation and tumor growth via platelet-derived growth factor-C.

Recent studies have revealed that the maturation state of vessels in tumors, in addition to vascularity, is a critical determinant of tumor growth. The role of oxygen-dependent signaling pathways in hypoxia-stimulated angiogenesis is well established, however, little is known about their impact on vessel maturation in tumors. Here, we have studied the function of the cellular oxygen sensor, factor inhibiting HIF-1 (FIH), which controls the activity of hypoxia-inducible factor-1.

Cellular oxygen sensing: Importins and exportins are mediators of intracellular localisation of prolyl-4-hydroxylases PHD1 and PHD2.

Hypoxia-inducible factors are crucial in the regulatory process of oxygen homeostasis of vertebrate cells. Inhibition of prolyl hydroxylation of HIF-alpha subunits by prolyl-hydroxylases (PHD1, PHD2 and PHD3) leads to transcription of a greater number of hypoxia responsive genes. We have investigated the subcellular distribution and the molecular mechanisms regulating the intracellular allocation of PHD1 and PHD2.