Inactivation of p53 Is Sufficient to Induce Development of Pulmonary Hypertension in Rats

Area of Science:

• Cardiovascular Research
• Molecular Biology
• Oncology

Background:

• Pulmonary arterial hypertension (PAH) shares cellular similarities with cancer.
• The tumor suppressor protein p53 and its pathway are crucial in regulating cell growth and apoptosis.
• p53 is often inactivated in various cancers, prompting investigation into its role in PAH.

Purpose of the Study:

• To investigate the role of the p53 pathway in pulmonary hypertension (PH).
• To explore the effects of p53 inactivation on PH pathogenesis using the monocrotaline (MCT) rat model.
• To assess the impact of pifithrin-α (PFT), a p53 inhibitor, on PH development.

Main Methods:

• Pulmonary hypertension (PH) was induced using monocrotaline (MCT) and assessed via pulmonary arterial pressure, right ventricular hypertrophy, and arterial wall thickness.
• p53 pathway protein expression (p53, p21, MDM2) was analyzed using Western blot.
• The effects of pifithrin-α (PFT) on cell apoptosis and proliferation were evaluated using TUNEL and MTT assays in cultured human PA-SMCs.

Main Results:

• Both MCT and chronic PFT treatment induced PH, with PFT aggravating MCT-induced PH.
• During the initial week after MCT administration, p53, p21, and MDM2 protein levels were significantly reduced prior to PH onset.
• PFT treatment demonstrated anti-apoptotic and pro-proliferative effects on pulmonary artery smooth muscle cells (PA-SMCs).

Conclusions:

• Pharmacological inactivation of p53 using PFT is sufficient to induce PH.
• The observed PH induction by PFT is linked to its anti-apoptotic and pro-proliferative properties.
• Down-regulation of the p53 pathway in the early stages of the MCT model suggests its involvement in PH pathogenesis.