PI-103

PI-103 is a potent and selective inhibitor of class I PI3K, mTOR and DNA-PK with IC50 values of 2, 3, 3, 15, 30 and 23 nM for p110α, p110β, p110δ, p110γ, mTOR and DNA-PK, respectively [1].

PI-103 showed potent antiproliferation activities in various cancer cell lines such as prostate, ovary and glioblastoma. It exerted GI50 values of 0.14, 0.06, 0.13, 0.10, 0.12 and 0.08 μM in U87MG, IGROV-1, DETROIT-562, PC3, SKOV-3 and HUVEC cells, respectively. In U87MG cells, 2 hour-treatment of PI-103 caused inhibition effects on various phosphorylated protein biomarkers of PI3K pathway with IC50 values of 15, 36, 111, 106 and 105 nM for p-AKTSer473, p-AKTThr308, p-GSK3βSer9, p-p70S6KThr421/Ser424 and p-S6RPSer235/Ser236, respectively [1].

References:
[1] Raynaud F I, Eccles S A, Patel S, et al. Biological properties of potent inhibitors of class I phosphatidylinositide 3-kinases: from PI-103 through PI-540, PI-620 to the oral agent GDC-0941. Molecular cancer therapeutics, 2009, 8(7): 1725-1738.

PI-103 attenuates PI3K-AKT signaling and induces apoptosis in murineT-cell lymphoma.[Pubmed:27658642]

Leuk Lymphoma. 2017 May;58(5):1153-1161.

Aberrant activation of PI3K-AKT signaling in many pathological conditions including cancer has attracted much of interest for drug targeting. Various isoforms are known from three classes of PI3K. Targeting selective isoform is advantageous to overcome the global deleterious effects of drug. PI-103 is a specific inhibitor of p110alpha of class I PI3K. The present study is aimed to analyze anti-carcinogenic activity of PI-103 in Dalton's lymphoma ascite (DLA) cells. Result shows regression in cell proliferation and increased apoptosis in terms of increased Annexin V binding, nuclear fragmentation and active caspase 3 level. It is correlated with attenuation of PI3K-AKT signaling by PI-103 via downregulation of the level of p110alpha, phospho-p85alpha, phospho- AKT, and PKCalpha in DLA cells as well as in H2O2 induced DLA cells. Additionally, ROS accumulation is declined in H2O2 induced DLA cells. Overall result suggests that PI-103 attenuates PI3K-AKT signaling via induction of apoptosis in murine T-cell lymphoma.

[A dual PI3K/mTOR inhibitor, PI-103, cooperates with TRAIL in laryngeal squamous carcinoma cells in vitro].[Pubmed:27464548]

Zhonghua Yi Xue Za Zhi. 2016 Jul 19;96(27):2187-91.

OBJECTIVE: To investigate the effects of a dual phosphoinosmde-3-kinase (PI3K)/ mammalian target of rapamycin (mTOR) inhibitor, PI-103, cooperating with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) on the laryngeal squamous carcinoma Hep-2 cells. METHODS: Hep-2 cells were divided into 7 groups: LY294002 group, Rapamycin group, PI-103 group, LY294002+ TRAIL group, Rapamycin+ TRAIL group, PI-103+ TRAIL group and control group.The cell cycle and apoptosis of Hep-2 cells were assessed by flow cytometry.For PI-103 group, PI-103+ TRAIL group and control group, migration and invasion ability were measured by transwell migration and invasion assay respectively.The expression of relative proteins in apoptosis and PI3K/AKT/mTOR signal pathway was examined by Western blotting. RESULTS: Combination of PI-103 and TRAIL could make cell cycle arrest at S phase (G1: 1.80%+/-0.30%; G2: 0.00), inhibit cell proliferation, and enhance apoptosis (66.78%+/-2.93%) (P<0.05). Combination of PI-103 and TRAIL could statistically decrease the migration and invasion number of Hep-2 cells (17.0+/-3.4, 18.4+/-5.4) than that of PI-103 group (41.2+/-3.8, 41.6+/-4.7). PI-103 could inhibit PI3K/AKT/mTOR signal pathway by decreasing the protein expression of p-AKT and p-4E-BP1.Comparing with the control group, the expression of cysteinyl aspartate specific proteinase (Caspase) 9, 8, 3 were increased while the expression of Cyclin D1, Cyclin E1, p-AKT, p-4E-BP1 were decreased in PI-103 and PI-103+ TRAIL group (P<0.05). CONCLUSION: Enhanced anti-tumor effects was observed by combination of PI-103 and TRAIL on laryngeal cancer cells in vitro and this combined administration might be a promising strategy for clinical treatment of laryngeal cancer.

Dual PI3K- and mTOR-inhibitor PI-103 can either enhance or reduce the radiosensitizing effect of the Hsp90 inhibitor NVP-AUY922 in tumor cells: The role of drug-irradiation schedule.[Pubmed:27224913]

Oncotarget. 2016 Jun 21;7(25):38191-38209.

Inhibition of Hsp90 can increase the radiosensitivity of tumor cells. However, inhibition of Hsp90 alone induces the anti-apoptotic Hsp70 and thereby decreases radiosensitivity. Therefore, preventing Hsp70 induction can be a promising strategy for radiosensitization. PI-103, an inhibitor of PI3K and mTOR, has previously been shown to suppress the up-regulation of Hsp70. Here, we explore the impact of combining PI-103 with the Hsp90 inhibitor NVP-AUY922 in irradiated glioblastoma and colon carcinoma cells. We analyzed the cellular response to drug-irradiation treatments by colony-forming assay, expression of several marker proteins, cell cycle progression and induction/repair of DNA damage. Although PI-103, given 24 h prior to irradiation, slightly suppressed the NVP-AUY922-mediated up-regulation of Hsp70, it did not cause radiosensitization and even diminished the radiosensitizing effect of NVP-AUY922. This result can be explained by the activation of PI3K and ERK pathways along with G1-arrest at the time of irradiation. In sharp contrast, PI-103 not only exerted a radiosensitizing effect but also strongly enhanced the radiosensitization by NVP-AUY922 when both inhibitors were added 3 h before irradiation and kept in culture for 24 h. Possible reasons for the observed radiosensitization under this drug-irradiation schedule may be a down-regulation of PI3K and ERK pathways during or directly after irradiation, increased residual DNA damage and strong G2/M arrest 24 h thereafter. We conclude that duration of drug treatment before irradiation plays a key role in the concomitant targeting of PI3K/mTOR and Hsp90 in tumor cells.

PI-103 and Quercetin Attenuate PI3K-AKT Signaling Pathway in T- Cell Lymphoma Exposed to Hydrogen Peroxide.[Pubmed:27494022]

PLoS One. 2016 Aug 5;11(8):e0160686.

Phosphatidylinositol 3 kinase-protein kinase B (PI3K-AKT) pathway has been considered as major drug target site due to its frequent activation in cancer. AKT regulates the activity of various targets to promote tumorigenesis and metastasis. Accumulation of reactive oxygen species (ROS) has been linked to oxidative stress and regulation of signaling pathways for metabolic adaptation of tumor microenvironment. Hydrogen peroxide (H2O2) in this context is used as ROS source for oxidative stress preconditioning. Antioxidants are commonly considered to be beneficial to reduce detrimental effects of ROS and are recommended as dietary supplements. Quercetin, a ubiquitous bioactive flavonoid is a dietary component which has attracted much of interest due to its potential health-promoting effects. Present study is aimed to analyze PI3K-AKT signaling pathway in H2O2 exposed Dalton's lymphoma ascite (DLA) cells. Further, regulation of PI3K-AKT pathway by quercetin as well as PI-103, an inhibitor of PI3K was analyzed. Exposure of H2O2 (1mM H2O2 for 30min) to DLA cells caused ROS accumulation and resulted in increased phosphorylation of PI3K and downstream proteins PDK1 and AKT (Ser-473 and Thr-308), cell survival factors BAD and ERK1/2, as well as TNFR1. However, level of tumor suppressor PTEN was declined. Both PI-103 & quercetin suppressed the enhanced level of ROS and significantly down-regulated phosphorylation of AKT, PDK1, BAD and level of TNFR1 as well as increased the level of PTEN in H2O2 induced lymphoma cells. The overall result suggests that quercetin and PI3K inhibitor PI-103 attenuate PI3K-AKT pathway in a similar mechanism.