Abstract 644: Role of Micro RNA LET-7F in Cigarette Smoke-Induced Impairment of Neovascularization
Background: Exposure to cigarette smoke is associated with impaired neovascularization in response to ischemia. The precise mechanisms involved in that process remain to be determined. Micro RNA (miR) are emerging as key regulators of several physiological processes, including angiogenesis. Here we investigated the potential role of miRs for the modulation of neovascularization in the context of cigarette smoking.
Methods and Results: Human Umbilical Vascular Endothelial Cells (HUVECs) were exposed or not to cigarette smoke extracts (CSE). Using Affimetrix GeneChip miRNA array analysis, we found that the pro-angiogenic miR let-7f was downregulated by 40% in HUVECs exposed to CSE. Using an inhibitor of let-7f, we demonstrated reduced migration and tube formation in HUVECs, reproducing the phenotype induced by CSE. A let-7f mimic could rescue cellular migration and tube formation in HUVECs exposed to CSE. Moreover, the expression of let-7f is significantly reduced in the ischemic muscles of mice exposed to cigarette smoke (CS). In vivo, hindlimb ischemia was surgically provoked by femoral artery removal to mice exposed (SMK) or not to CS for two weeks with a local injection of a control or a let-7f mimic. Let-7f mimic could rescue blood flow recuperation and capillary density in ischemic muscles 21 days post-ischemia associated with improved mobility. We found that CS was associated with reduced number of endothelial progenitor cells (EPCs) and impairment of angiogenic activities. Importantly, let-7f mimic rescued EPC number and EPC functional activities in SMK group. TGF-β-RI and HIF1AN are predicted to be targeted by let-7f and both are increased in SMK mice, whereas the expression of HIF-1a and VEGF are reduced in these mice. Interestingly, SMK mice injected with a let-7f mimic have decreased muscle expression of TGF-β-RI and HIF1AN associated with normalized HIF-1 and VEGF expression.
Conclusion: Our results suggest that a reduction in the expression of let-7f could be involved in the cigarette smoke-induced inhibition of angiogenesis through modulation of TGF-β-RI and HIF1AN. Overexpression of let-7f using a miR mimic could constitute a novel therapeutic strategy to improve ischemia-induced neovascularization in pathological conditions.
Author Disclosures: W. Dhahri: None. S. Dussault: None. P. Haddad: None. J. Turgeon: None. S. Tremblay: None. M. Desjarlais: None. R. Mathieu: None. A. Rivard: None.
- © 2015 by American Heart Association, Inc.