Abstract 14862: miR-223 Regulates DNA Damage Signaling in Pulmonary Arterial Hypertension
Background: Pulmonary arterial hypertension (PAH) is a devastating disease affecting lung vasculature. The pulmonary arteries become occluded due to increased proliferation and suppressed apoptosis of the pulmonary artery smooth muscle cells (PASMCs) within the vascular wall. We recently showed that the DNA damage activated PARP-1 was overexpressed in PAH and responsible for the proliferation/apoptosis imbalance in PAH-PASMCs. Nevertheless, the mechanism that regulates its overexpression in PAH remains elusive. In silico analyses and studies in cancer demonstrated that microRNA miR-223 targets PARP-1. We thus hypothesized that miR-223 downregulation triggers PARP-1 overexpression, as well as the proliferation/apoptosis imbalance observed in PAH.
Methods and Results: Using qRT-PCR, we demonstrated that miR-223 is significantly decreased in human lungs, distal pulmonary arteries (PAs) and isolated PASMCs of PAH patients compared to control donors (n=5-10, p<0.01). PAH-PASMCs isolated from distal PAs exhibited a 2.5-fold decrease in miR-223 expression (n=5, p<0.05). Furthermore, using a gain and loss of function approach, we showed that increased HIF-1α (using siRNA and adenoviruses) triggers miR-223 downregulation, subsequent overexpression of PARP-1 (n=5, p<0.05) and alterations in DNA damage repair (γ-H2AX, n=4, p<0.05). Using a bidirectionnal approach, we showed that decreased miR-223 triggers the proliferation/apoptosis imbalance observed in PAH-PASMC (Ki67 and AnnexinV, n=5, p<0.05). Finally, we demonstrated that restoring the expression of miR-223, by nebulization of miR-223 mimics in lungs of rats with monocrotaline-induced PAH reversed established PAH as assessed by right heart catheterization (mean PA pressure, cardiac output) and provided beneficial effects on vascular remodeling (H&E), pulmonary resistance, right ventricle hypertrophy and survival (n=8-10 per group, p<0.05).
Conclusion: We provide evidences that miR-223 downregulation in PAH plays an important role in numerous pathways implicated in the disease and restoring its expression is able to reverse PAH.
Author Disclosures: J. Meloche: None. M. Le Guen: None. F. Potus: None. B. Ranchoux: None. F. Antigny: None. E. Tremblay: None. S. Breuils-Bonnet: None. F. Perros: None. S. Provencher: None. S. Bonnet: None.
- © 2015 by American Heart Association, Inc.