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Inhibition of Phosphatidylinositol 3-Kinase γ by IPI-549 Attenuates Abdominal Aortic Aneurysm Formation in Mice

Objective: The phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signalling pathway plays a pivotal role in abdominal aortic aneurysm (AAA). However, systemic inhibition of this pathway causes serious side effects, thus limiting the clinical use of pan-PI3K inhibitors. In this study, it was hypothesised that the γ subunit of PI3K plays an important role in the PI3K/AKT signalling pathway during AAA, and that specifically targeting PI3Kγ may prevent this process.

Methods: Aortic specimens were collected from AAA patients and organ donors. Furthermore, a classical AAA model in male C57BL/6 mice was created via an intra-aortic porcine pancreatic elastase (PPE) infusion and aortas were collected. A specific PI3Kγ inhibitor, IPI-549, was administered to mice orally. The protein expression level of PI3Kγ was examined by immunohistochemistry and western blotting. The aortic leukocytes were examined by immunohistochemistry and flow cytometry.

Results: PI3Kγ protein levels were elevated in the aortas of AAA patients and PPE infused mice. Three color immunofluorescence staining revealed the predominant area of PI3Kγ by T cells and macrophages in aneurysmal aortas. IPI-549 treatment significantly prevented AAA formation in mice. Aortic macrophages, T cells and neo-angiogenesis were significantly reduced in mice treated with IPI-549 compared with vehicle treated PPE infused mice. Flow cytometry analysis also revealed that CD45+ leukocytes and CD45+ F4/80+ macrophages in IPI-549 treated mouse aortas decreased dramatically. Additionally, IPI-549 treatment inhibited the phosphorylation of AKT in experimental aneurysmal lesions.

Conclusion: Specific inhibition of PI3Kγ limits AAA formation. Targeting PI3Kγ prevents inflammatory cell infiltration through inhibition of AKT phosphorylation in AAA.

Related Products

Cat.No. Product Name Information
S8330 Eganelisib (IPI-549) Eganelisib (IPI-549) is a potent inhibitor of PI3K-γ with >100-fold selectivity over other lipid and protein kinases. The biochemical IC50 for PI3K-γ is 16 nM.

Related Targets

PI3K