Angiogenic effect of laminin involves modulation of cyclooxygenase-2 and prostaglandin levels

Regulation of vascular endothelial growth factor by metabolic context of the cell

Expression of vascular endothelial growth factor, major endothelial specific glycoprotein growth factor that promotes angiogenesis is regulated at transcriptional, post transcriptional and posttranslational levels. One of the key posttranslational modifications involved in regulating the angiogenic potential of VEGF is covalent modification involving polyADP ribosylation. Major factors contributing to the regulation of VEGF include factors relating to hypoxia, growth factors and cytokines and hormones. Apart from these, the metabolite status of the cell as sensed by various metabolite regulators can influence the angiogenic potential. Changes in the metabolite status of the cell occur during different conditions associated with excessive or insufficient angiogenesis contributing to pathology. Effect of metabolites, as exemplified by certain metabolites such as lactate, citrate, sarcosine, metabolites of arachidonic acid on angiogenesis through the regulation of expression of VEGF as well as its angiogenic potential through polyADP ribosylation is discussed.

Effect of 15-lipoxygenase metabolites on angiogenesis: 15(S)-HPETE is angiostatic and 15(S)-HETE is angiogenic

OBJECTIVE

15(S)-Hydroxyeicosatetraenoic acid [15(S)-HETE] and 15(S)-hydroperoxyeicosatetraenoic acid [15(S)-HPETE] are the products of arachidonic acid formed in the 15-lipoxygenase pathway. They have opposing effects on the inflammatory process. The present study was designed to examine the role of these metabolites on angiogenesis, which is critically associated with inflammatory conditions.

METHODS

Chick chorio-allantoic membrane (CAM), rat aortic rings and human umbilical vein endothelial cells (HUVECs) in culture were used to study the effect of 15(S)-HETE and 15(S)-HPETE on angiogenesis. Biochemical markers of angiogenesis were analysed by ELISA.

RESULTS

15(S)-HETE increased vessel density in chick CAM, induced sprouting in rat aortic rings and increased endothelial cell-cell contact and formation of tubular network-like structures in HUVECs. Furthermore, it up-regulated the expression of CD31, E-selectin and vascular endothelial growth factor (VEGF) in HUVECs, indicating its pro-angiogenic effect. 15(S)-HPETE, on the other hand, decreased vessel density in chick CAM, down-regulated the expression of E-selectin (<35 %), VEGF (<90 %) and CD31 (<50 %) and did not produce sprouting in aortic rings, suggesting an anti-angiogenic property. 15(S)-HETE-mediated up-regulation of CD 31 and VEGF was reversed by treatment with 15(S)-HPETE.

CONCLUSION

These results indicate the divergent effects of hydroxy and hydroperoxy products of 15-LOX on angiogenesis, highlighting the role of these products in the co-dependence of inflammation and angiogenesis.