Benzo[a]pyrene Inhibits Angiogenic Factors–Induced αvβ3 Integrin Expression, Neovasculogenesis, and Angiogenesis in Human Umbilical Vein Endothelial Cells

Abstract

New blood vessel formation is necessary for the repair of ischemia-damaged tissues. Endothelial cells produce exogenous and endogenous angiogenic factors in the mediation of angiogenesis and neovasculogenesis during neovascularization. Exposure to environmental pollutants may alter proangiogenic capacity or desensitize the responses of endothelial cells to stimulation by basic fibroblast growth factor and vascular endothelial growth factor. Human umbilical vein endothelial cells (HUVECs) were pretreated with benzo[a]pyrene (B[a]P), the major carcinogenic constituent found in tobacco smoke, for 24 h. Neovasculogenesis, migration, and proliferation were evaluated in solvent-treated and B[a]P-treated HUVECs. Endothelial capillary-like tube formation, cell migration, mitogen-activated protein kinase (MAPK) phosphorylation, and integrin expression were reduced in B[a]P-treated HUVECs with angiogenic factor stimulation, in comparison to solvent-treated HUVECs, although cell proliferation and Akt activation remained unaffected. Inhibition of B[a]P-mediated MAPK and neovasculogenesis was significantly rescued by pretreatment with α-naphthoflavone, an aryl hydrocarbon receptor (AhR) antagonist. The B[a]P-mediated inhibition of neovasculogenesis was also rescued in AhR-silenced HUVECs, suggesting the requirement for AhR in B[a]P-associated effects. B[a]P also inhibited angiogenesis in a chorioallantoic membrane assay. We conclude that B[a]P is a potent inhibitor of angiogenesis, and its effects are mediated via AhR-dependent phenotypic changes in B[a]P-treated HUVECs. These findings contribute to an understanding of the involvement of AhR agonists in vasculotoxicity.

ITE Suppresses Angiogenic Responses in Human Artery and Vein Endothelial Cells: Differential Roles of AhR

“…In addition, since vein and artery endothelial cells are tremendously different in their global gene expression profiles [27–29], it is very likely that ITE stimulation may differentially alter gene expression profiles between artery and vein endothelial cells, leading to different angiogenic responses as we observed in the current study. Interestingly, ITE also does not slow down the cell cycle progression of either HUVECs or HUAECs, which is contrast to previous report that 3-MC arrests the cell cycle at G0/G1 [33]. In the current study, the time points (24, 36, and 144 hr) studied are within the optimal time frame to detect changes in the cell progress since the estimated doubling times are ~ 40 and 52 hr for HUVECs and HUAECs, respectively, which are similar to the previously reported ones (47 and 46 hr) for HUVECs and HUAECs, respectively [36].…”

“…The current observation that ITE-suppressed cell proliferation and viability of HUVECs and HUAECs is consistent with activities of another AhR ligand, benzo[a]pyrene (B[a]P), which inhibits angiogenic factors-induced neovasculogenesis and angiogenic activity of HUVECs [33]. The ITE-suppressed cell proliferation of HUVECs and HUAECs is associated with the decreased cell viability as indicated by the decreased activity of mitochondrial dehydrogenases enzyme (intracellular NADPH-oxidoreductases) within the live cells in the MTT assay (Fig.…”

ITE inhibits growth of human pulmonary artery endothelial cells

“…2B) and human umbilical vein endothelial cells (HUVECs) [14] and is in line with a previous report showing that benzo(a)pyrene (another exogenous AhR ligand) inhibited neovasculogenesis in vivo and angiogenic activity of HUVECs in vitro . [28] However, the current data are contrary to the other previous studies, [29,30] in which TCDD failed to affect growth of many human and animal primary cells and transformed cell lines (not including HPAECs). More interestingly, the ITE-inhibited growth of HPAECs is independent of AhR since knockdown of AhR did not significantly affect this inhibition, although AhR has been shown to mediate ITE-inhibited growth of ovarian cance cells.…”

Anti-angiogenic effects of thioridazine involving the FAK-mTOR pathway

“…Flow cytometry analysis for αvβ3 integrin expression αvβ3 Integrin expression was performed as described previously (Li et al, 2010). In brief, cells were trypsinized, washed, and resuspended in PBS, respectively.…”