PKI PKA Inhibitor (5-24) is a synthetic peptide inhibitor of PKA (cAMP-dependent protein kinase) (Ki= 2.3 nM) derived from the active site of the skeletal muscle inhibitor protein.1It mimics the protein substrate by binding to the catalytic site through the arginine-cluster basic subsite.1The prominent enzyme-substrate interaction site occurs where PKA catalytic subunit residues Tyr235and Phe239form a sandwich-like structure with residue Phe10of PKI (5-24).2
PKI-179 is a potent and orally active dual PI3K mTOR inhibitor, with IC50s of 8 nM, 24 nM, 74 nM, 77 nM, and 0.42 nM for PI3K-α, PI3K-β, PI3K-γ, PI3K-δ and mTOR, respectively. PKI-179 also exhibits activity over E545K and H1047R, with IC50s of 14 nM and 11 nM, respectively. PKI-179 shows anti-tumor activity in vivo[1][2]. PKI-179 inhibits the cell proliferation, with IC50s of 22 nM and 29 nM for MDA361 and PC3 cells, respectively[1].PKI-179 shows inhibitory activity against a panel of 361 other kinases, hERG and cytochrome P450 (CYP) isoforms at concentrations up to >30 μM, but does have activity for CYP2C8 (IC50=3 μM)[1]. PKI-179 (5-50 mg kg; p.o. once daily for 40 days) inhibits the tumor growth and is well tolerated in nude mice bearing MDA-361 human breast cancer tumors[1].PKI-179 (50 mg kg; p.o.) results in good inhibition of PI3K signaling in nude mice bearing MDA361 tumor xenografts[1].PKI-179 exhibits good oral bioavailability (98% in nude mouse, 46% in rat, 38% in monkey, and 61% in dog) and a high half-life (>60 min) [1]. [1]. Venkatesan AM, et, al. PKI-179: an orally efficacious dual phosphatidylinositol-3-kinase (PI3K) mammalian target of rapamycin (mTOR) inhibitor. Bioorg Med Chem Lett. 2010 Oct 1;20(19):5869-73.[2]. Rehan M. A structural insight into the inhibitory mechanism of an orally active PI3K mTOR dual inhibitor, PKI-179 using computational approaches. J Mol Graph Model. 2015 Nov;62:226-234.