CircDiaph3 influences PASMC apoptosis by regulating PI3K/AKT/mTOR pathway through IGF1R

The pathogenesis of pulmonary hypertension has not been elucidated. We investigated the role of a circular ribonucleic acid, circDiaph3, in the proliferation and migration of pulmonary artery smooth muscle cells during pulmonary hypertension. CircDiaph3 overexpression in blood samples of patients with pulmonary hypertension was analyzed by real-time quantitative polymerase chain reaction. Subsequently, a rat model of pulmonary arterial hypertension was established under hypoxic conditions. Pulmonary artery smooth muscle cells were harvested from the rat model for subsequent experiments with small interfering ribonucleic acid-mediated knockdown of circDiaph3. In cell model, we found that PI3K, AKT, mTOR and insulin-like growth factor 1 signaling pathway (IGF1R) and smooth muscle cell marker genes (α-SMA, Vcam1) were significantly downregulated. The overexpression of Igf1r in pulmonary artery smooth muscle cells rescued the downregulated smooth muscle cell genes, IGF1R signaling pathway proteins, increased smooth muscle cell proliferation, and reduced apoptosis. CircDiaph3 regulates the PI3K/AKT/mTOR signaling pathway via IGF1R to inhibit apoptosis and promote proliferation of smooth muscle cells. Additionally, adenovirus-mediated in vivo inhibition of circDiaph3 was carried out in rats with pulmonary arterial hypertension, followed by harvesting of their pulmonary artery smooth muscle cells for subsequent experiments. Excessive proliferation of smooth muscle cells in the pulmonary artery has narrowed the pulmonary artery lumen, thereby causing pulmonary hypertension, and our results suggest that circDiaph3 has important value in the treatment of pulmonary hypertension.