Established pulmonary hypertension in rats was reversed by a combination of a HIF-2α antagonist and a p53 agonist.

Recent studies reported therapeutic effects of monotherapy with either tumour suppressor p53 (p53) agonist or hypoxia-inducible factor 2α (HIF-2α) antagonist for pulmonary hypertension (PH). This study investigated whether a combined treatment of p53 agonist, Nutlin3a, and HIF-2α antagonist, PT2385, would be more effective than monotherapy, based on the cell type-divergent regulation of p53 in pulmonary arterial smooth muscle cells (PASMC) and endothelial cells (PAEC) in patients and animals with PH. The SU5416/hypoxia-induced PH (SuHx-PH) rat model was used, along with cultured human PASMC and PAEC. Western blot, RT-PCR, siRNA and immunohistochemical methods were used along with echocardiography and studies with isolated pulmonary arteries. Hypoxia-induced proliferation of PASMC is associated with decreased p53, whereas hypoxia-induced PAEC apoptosis is associated with increased p53, via a HIF-2α-dependent mechanism. Combined treatment with Nutlin3a and PT2385 is more effective by simultaneously inhibiting the hypoxia-induced PASMC proliferation and PAEC apoptosis, overcoming the side-effects of monotherapy. These are (i) Nutlin3a exacerbates hypoxia-induced PAEC apoptosis by inducing p53 in PAEC and (ii) PT2385 inhibits PAEC apoptosis because HIF-2α is predominantly expressed in PAEC but lacks direct effects on the hypoxia-induced PASMC proliferation. In rats, combination treatment is more effective than monotherapy in reversing established SuHx-PH, especially in protecting pulmonary arterial vasculature, by normalizing smooth muscle thickening, protecting against endothelial damage and improving function. Combination treatment confers greater therapeutic efficacy against PH through a selective modulation of p53 and HIF-2α in PASMC and PAEC.

Zheng Q ，Lu W ，Yan H ，Duan X ，Chen Y ，Zhang C ，Luo X ，Chen J ，Wang C ，Liu S ，Li Y ，Tang H ，Rahimi S ，Rahimi S ，Yuan JX ，Zhong N ，Yang K ，Wang J ... -  《-》

Divergent changes of p53 in pulmonary arterial endothelial and smooth muscle cells involved in the development of pulmonary hypertension.

Wang Z ，Yang K ，Zheng Q ，Zhang C ，Tang H ，Babicheva A ，Jiang Q ，Li M ，Chen Y ，Carr SG ，Wu K ，Zhang Q ，Balistrieri A ，Wang C ，Song S ，Ayon RJ ，Desai AA ，Black SM ，Garcia JGN ，Makino A ，Yuan JX ，Lu W ，Wang J ... -  《-》

[Effect of HIF-2α mediated FoxM1 expression on proliferation of pulmonary artery smooth muscle cells in hypoxic rats].

Zhu H ，Zhu LM ，Jiang YL ，Hu RC ，Dai AG ... -  《-》

Endothelial HIF-2α contributes to severe pulmonary hypertension due to endothelial-to-mesenchymal transition.

Tang H ，Babicheva A ，McDermott KM ，Gu Y ，Ayon RJ ，Song S ，Wang Z ，Gupta A ，Zhou T ，Sun X ，Dash S ，Wang Z ，Balistrieri A ，Zheng Q ，Cordery AG ，Desai AA ，Rischard F ，Khalpey Z ，Wang J ，Black SM ，Garcia JGN ，Makino A ，Yuan JX ... -  《-》

Smooth muscle cell-specific FoxM1 controls hypoxia-induced pulmonary hypertension.

Forkhead box M1 (FoxM1) is a transcription factor that promotes cell proliferation by regulating a broad spectrum of genes that participate in cell cycle regulation, such as Cyclin B, CDC25B, and Aurora B Kinase. We have shown that hypoxia, a well-known stimulus for pulmonary hypertension (PH), induces FoxM1 in pulmonary artery smooth muscle cells (PASMC) in a HIF-dependent pathway, resulting in PASMC proliferation, while the suppression of FoxM1 prevents hypoxia-induced PASMC proliferation. However, the implications of FoxM1 in the development of PH remain less known. We determined FoxM1 levels in the lung samples of idiopathic PAH (pulmonary arterial hypertension) (IPAH) patients and hypoxia-induced PH mice. We generated constitutive and inducible smooth muscle cell (SMC)-specific FoxM1 knockdown or knockout mice as well as FoxM1 transgenic mice which overexpress FoxM1, and exposed them to hypoxia (10% O2, 90% N2) or normoxia (Room air, 21% oxygen) for four weeks, and measured PH indices. We also isolated mouse PASMC (mPASMC) and mouse embryonic fibroblasts (MEF) from these mice to examine the cell proliferation and expression levels of SMC contractile proteins. We showed that in hypertensive human lungs or mouse lungs, FoxM1 levels were elevated. Constitutive knockout of FoxM1 in mouse SMC caused early lethality, whereas constitutive knockdown of FoxM1 in mouse SMC prevented hypoxia-induced PH and PASMC proliferation. Inducible knockout of FoxM1 in SMC reversed hypoxia-induced pulmonary artery wall remodeling in existing PH. Overexpression of FoxM1 enhanced hypoxia-induced pulmonary artery wall remodeling and right ventricular hypertrophy in mice. Alteration of FoxM1 status did not affect hypoxia-induced hypoxia-inducible factor (HIF) activity in mice. Knockout of FoxM1 decreased PASMC proliferation and induced expression of SMC contractile proteins and TGF-β/Smad3 signaling. Our studies provide clear evidence that altered FoxM1 expression in PASMC contributes to PH and uncover a correlation between Smad3-dependent signaling in FoxM1-mediated proliferation and de-differentiation of PASMC.

Dai J ，Zhou Q ，Tang H ，Chen T ，Li J ，Raychaudhuri P ，Yuan JX ，Zhou G ... -  《-》