A Central Role for Nicotinic Cholinergic Regulation of Growth Factor–Induced Endothelial Cell Migration

Abstract

Objective— An endothelial nicotinic acetylcholine receptor (nAChR) participates in atherogenesis and tumorigenesis by promoting neovascularization. To date, the mechanisms of nAChR-mediated angiogenesis and their relationship to angiogenic factors, eg, VEGF and bFGF, are unknown. Methods and Results— Nicotine induced dose-dependent human microvascular endothelial cell (HMVEC) migration, a key angiogenesis event, to an extent which was equivalent in magnitude to bFGF (10 ng/mL) but less than for VEGF (10 ng/mL). Unexpectedly, nAChR antagonism not only abolished nicotine-induced HMVEC migration but also abolished migration induced by bFGF and attenuated migration induced by VEGF. Transcriptional profiling identified gene expression programs which were concordantly regulated by all 3 angiogens (nicotine, VEGF, and bFGF), a notable feature of which includes corepression of thioredoxin-interacting protein (TXNIP), endogenous inhibitor of the redox regulator thioredoxin. Furthermore, TXNIP repression by all 3 angiogens induced thioredoxin activity. Silencing thioredoxin by small interference RNA abrogated all angiogen-induced migration while silencing TXNIP strongly induced HMVEC migration. Interestingly, nAChR antagonism abrogates growth factor (VEGF and bFGF)–mediated induction of thioredoxin activity. Conclusions— Nicotine promotes angiogenesis via stimulation of nAChR-dependent endothelial cell migration. Furthermore, growth factor–induced HMVEC migration, a key angiogenesis event, requires nAChR activation—an effect mediated in part by nAChR-dependent regulation of thioredoxin activity.

Mechanisms of growth-promoting and tumor-protecting effects of epithelial nicotinic acetylcholine receptors

“…The SCC25 and SW900 cells were seeded at a density of 1 × 10 4 per well of a 96-well plate and incubated for 24 h in the absence (intact control) or presence of 0.1 μM of nicotine ± 10 μM Mec and/or 1 μM αBtx or 10 ng/ml of each tested GF ± 0.1 μM nicotine, after which the cells were suspended and the number of the TBD-positive (dead) and negative (alive) cells were measured in a hemocytometer. We used the 10 ng/ml of EGF and VEGF, because in the pilot studies this concentration produced maximal effect, which is keeping with results reported in the literature [112,113]. In the apoptosis experiments, the cells were exposed to test agents in the presence of 100 μM H 2 O 2 for 12 h and then used in the TUNEL assay, as detailed in Materials and methods.…”

N-Hydroxy-6-(5-Nitro-Naphtalimide)-Hexanamide Inhibits Lysine Deacetylation, Mitigates Angiogenesis and Reduces Tumor Growth

“…Inhibition of cav-1 significantly reduces basal and VEGF-stimulated phosphorylation of VEGFR2, PLCγ1 and Akt thereby affecting VEGF induced tubule formation [42]. ES8, but not SAHA, up regulates TXNIP (thioredoxin-interacting protein), whose silencing stimulates thioredoxin activity and EC migration [43]. Conversely, SAHA affects genes not targeted by ES8, such as ANXA3 (annexin A3) that induces VEGF production through the HIF-1 pathway [44].…”

Functional properties of ion channels and transporters in tumour vascularization

“…In particular, a7 nAChR mediates the main effects of nicotine on EC, such as proliferation, survival, migration, tube formation and intracellular signalling. Interestingly, a9 and a7 nAChRs exert opposing effects on nicotine-induced cell proliferation and survival [41,42,69].…”