Effects Of Phosphoinositide 3-kinase Inhibitors Research Articles

Abstract A29: Targeted disruption of PI3K/Akt/mTOR signaling pathway induces cell cycle arrest, apoptosis, autophagy, and inhibits inflammation, invasion, and angiogenesis of OSCC cells

Abstract Purpose: The phosphoinositide-3-kinase (PI3K) pathway is frequently altered in human cancer. This has led to the development and study of novel PI3K inhibitors for targeted therapy and also to overcome resistance to radiotherapy. Method: The antitumor effects of PI3K inhibitors (PI-828, PI-103 and PX-866) in terms of cell proliferation, colony formation, induction of apoptosis, cell cycle arrest, invasion, autophagy, and pNF- κB/p65 translocation in SCC-4, SCC-9 and SCC-25 cells were studied by performing MTT, clonogenic, DAPI staining, propidium iodide staining, annexin–V binding, Matrigel invasion, acridine orange staining and immunofluorescence assay. Western blot assay was performed to assess the alteration in the expression of various proteins. Result: PI-828 and PI-103 treatment exhibited dose-dependent inhibition of growth and proliferation of OSCC cells with a concomitant induction of apoptosis, altered cell cycle regulation and decreased invasiveness (p <0.01). PX-866 induced apoptosis, cell cycle arrest, autophagy and a significant decrease in the invasiveness of oral cancer cells as compared to untreated cells (p <0.01). These compounds significantly reduced expression of COX-2, Cyclin-D and VEGF in the treated cells besides cytoplasmic accumulation of pNF-κB/p65 protein. In addition to PI3Kα, inactivation of downstream components, i.e., Akt and mTOR was seen. Conclusion: PI3K inhibitors such as PI-103, PI-828 and PX-866 may be developed as potential chemotherapeutic agents for effective treatment of OSCC and other malignancies associated with activated PI3K/Akt pathway. Note: This abstract was not presented at the conference. Citation Format: Sadhna Aggarwal, Sarah John, Satya N. Das, Suresh C. Sharma. Targeted disruption of PI3K/Akt/mTOR signaling pathway induces cell cycle arrest, apoptosis, autophagy, and inhibits inflammation, invasion, and angiogenesis of OSCC cells [abstract]. In: Proceedings of the AACR Special Conference on Targeting PI3K/mTOR Signaling; 2018 Nov 30-Dec 8; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(10_Suppl):Abstract nr A29.

Abstract A60: Targeted disruption of PI3K/Akt/mTOR signaling pathway induces cell cycle arrest, apoptosis, and autophagy, and inhibits inflammation, invasion and angiogenesis of OSCC cells

Abstract Purpose: The phosphoinositide-3-kinase (PI3K) pathway is frequently altered in human cancer. This has led to the development and study of novel PI3K inhibitors for targeted therapy and also to overcome resistance to radiotherapy. Method: The antitumor effects of PI3K inhibitors (PI-828, PI-103 and PX-866) in terms of cell proliferation, colony formation, induction of apoptosis, cell cycle arrest, invasion, autophagy, and pNF-κB/p65 translocation in SCC-4, SCC-9 and SCC-25 cells was studied by performing MTT, clonogenic, DAPI staining, propidium iodide staining, annexin-V binding, Matrigel invasion, acridine orange staining and immunofluorescence assay. Western blot assay was performed to assess the alteration in the expression of various proteins. Results: PI-828 and PI-103 treatment exhibited dose-dependent inhibition of growth and proliferation of OSCC cells with a concomitant induction of apoptosis, altered cell cycle regulation and decreased invasiveness (p <0.01). PX-866 induced apoptosis, cell cycle arrest, autophagy and a significant decrease in the invasiveness of oral cancer cells as compared to untreated cells (p <0.01). These compounds significantly reduced expression of COX-2, Cyclin-D and VEGF in the treated cells besides cytoplasmic accumulation of pNF-κB/p65 protein. In addition to PI3Kα, inactivation of downstream components, i.e., Akt and mTOR, was seen. Conclusion: PI3K inhibitors such as PI-103, PI-828 and PX-866 may be developed as potential chemotherapeutic agents for effective treatment of OSCC and other malignancies associated with activated PI3K/Akt pathway. Note: This abstract was not presented at the conference. Citation Format: Sadhna Aggarwal, Sarah John, Suresh C. Sharma, Satya N. Das. Targeted disruption of PI3K/Akt/mTOR signaling pathway induces cell cycle arrest, apoptosis, and autophagy, and inhibits inflammation, invasion and angiogenesis of OSCC cells [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr A60.

Synergistic effects of 15-deoxy Δ12,14-prostaglandin J2 on the anti-tumor activity of doxorubicin in renal cell carcinoma

An endogenous anticancer agent, 15-deoxy -Δ12,14-prostaglandin J2 (15d-PGJ2) induces apoptosis in the chemoresistant renal cell carcinoma (RCC). Peroxisome proliferator-activated receptor-γ (PPARγ) is a nuclear receptor for 15d-PGJ2, and mediates the cytotoxicity of 15d-PGJ2 in many cancerous cells. However, 15d-PGJ2 induces apoptosis independently of PPARγ in human RCC cell line such as Caki-2. In the present study, we found that 15d-PGJ2 ameliorated the chemoresistance to one of anthracycline antibiotics, doxorubicin, in Caki-2 cells. Doxorubicin alone exhibited weak cytotoxicity at the concentrations effective for other cancer cells such as Hela cells. In addition, it did not activate caspase 3. However, the cytotoxicity of doxorubicin was increased remarkably and accompanied with the caspase- 3 activation in the presence of 15d-PGJ2. Doxorubicin alone damaged plasma membrane, and the combined application of 15d-PGJ2 with doxorubicin increased the membrane permeability slightly. PPARγ was involved in neither the anti-tumor activity nor the synergistic effect of 15d-PGJ2. 15d-PGJ2 induces apoptosis in Caki-2 cells via suppressing the phosphoinositide 3-kinase (PI3K)-Akt pathway. The effect of PI3K inhibitor on the cytotoxicity of doxorubicin was additive, but not synergistic. Although the PI3K inhibitor mimicked the cytotoxicity of 15d-PGJ2, it might not be involved in the synergism between 15d-PGJ2 and doxorubicin. In conclusion, 15d-PGJ2 enhanced the chemosensitivity of doxorubicin via the pathway independent of PPARγ and PI3K.

Abstract 1674: HER3 inhibition potentiates anti-tumor effects of PI3K inhibitors in pre-clinical models of HNSCC

Abstract Background: The phosphoinositide 3-kinase (PI3K) pathway is thought to be the most frequently mutated oncogenic pathway in head and neck squamous cell carcinoma (HNSCC). This pathway is often further activated by deregulated receptors such as the epidermal growth factor receptor family. HER3 has a direct phosphorylation site with the regulatory subunit of PIK3CA, and is being investigated as a potential co-target to increase anti-tumor effects of PI3K inhibition. In this investigation, we use blocking antibodies against HER3 and its ligand, neuregulin β-1, (KTN3379) and PIK3CA (BYL719) to investigate the effect of HER3 in modulating response to PI3K inhibition. Methods and Results: Treatment with neuregulin β-1 significantly increased phosphorylation of HER3, AKT, and S6 across HNSCC, regardless of baseline level of HER3 expression. HER3 inhibition (KTN3379) consistently abrogated these effects, and decreased baseline phosphorylation of HER3. Combined blockade of HER3 (KTN3379) and PI3K (BYL719) inhibits the growth of HNSCC cell lines more effectively than inhibition of a single receptor alone, in both cell proliferation and colony formation assays. Combined treatment decreases phosphorylation of AKT and S6 more effectively than inhibition with either drug in some HNSCC cell lines. Treatment with neuregulin β-1 diminishes the inhibitory effect of BYL719 on HNSCC cell growth. Furthermore, treatment of some HNSCC cell lines with BYL719 led to upregulation of the HER3 pathway in HNSCC cell lines by Western blotting analysis, suggesting a possible role of HER3 in PI3K resistance. Conclusion: HER3 interacts with PI3KCA, and the PI3K pathway in multiple HNSCC cell lines, and combined blockade leads to pronounced effects in pre-clinical models of HNSCC. These findings suggest that HER3 blockade, may be efficacious when combined with PI3K pathway inhibition. Citation Format: Kara S. Davis, Nayel Khan, Carolyn Kemp, Sucheta Kulkarni, Diego Alvarado, Theresa LaVallee, Jennifer R. Grandis, Umamaheswar Duvvuri. HER3 inhibition potentiates anti-tumor effects of PI3K inhibitors in pre-clinical models of HNSCC. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1674. doi:10.1158/1538-7445.AM2015-1674

Preventive and Therapeutic Effects of Phosphoinositide 3-Kinase Inhibitors on Acute Lung Injury

Phosphoinositide 3-kinases (PI3Ks) are involved in a number of biologic responses. Recent preclinical studies demonstrated that the PI3K-dominant signal pathway could play an important role in the development of acute lung injury, although the mechanism remains unclear. CD-1 mice were administered different PI3K inhibitors either intranasally or intragastrically once a day for 3 days before intratracheal instillation of lipopolysaccharide at 4 h and 24 h. Effects of SHBM1009 on lipopolysaccharide-induced capillary permeability, leukocyte distribution and activation, and epithelial cell function were measured. Therapeutic effects of SHBM1009 on pancreatic elastase-induced lung injury were evaluated in rats. The data demonstrated that the local delivery of PI3K inhibitors played more effective roles in the prevention of endotoxin-induced lung injury than the systemic delivery. The preventive effects of PI3K inhibitors varied most likely because of chemical properties, targeting sites, and pharmacokinetics. The local PI3K inhibitors prevented both endotoxin- and elastase-induced lung injury in mice and rats, possibly through directly inhibiting or inactivating the function of airway epithelial cells, which could not produce chemoattractant factors to activate neutrophils and macrophages. PI3K may be a therapeutic target for lung injury, and local delivery of PI3K inhibitors may be one of the optimal approaches for the therapy.

Lipid Products of Phosphoinositide 3-Kinase and Phosphatidylinositol 4′,5′-Bisphosphate Are Both Required for ADP-dependent Platelet Spreading

We have shown previously that ADP released upon platelet adhesion mediated by alphaIIb beta3 integrin triggers accumulation of phosphatidylinositol 3',4'-bisphosphate (PtdIns-3,4-P2) (Gironcel, D. , Racaud-Sultan, C., Payrastre, B., Haricot, M., Borchert, G., Kieffer, N., Breton, M., and Chap, H. (1996) FEBS Lett. 389, 253-256). ADP has also been involved in platelet spreading. Therefore, in order to study a possible role of phosphoinositide 3-kinase in platelet morphological changes following adhesion, human platelets were pretreated with specific phosphoinositide 3-kinase inhibitors LY294002 and wortmannin. Under conditions where PtdIns-3, 4-P2 synthesis was totally inhibited (25 microM LY294002 or 100 nM wortmannin), platelets adhered to the fibrinogen matrix, extended pseudopodia, but did not spread. Moreover, addition of ADP to the medium did not reverse the inhibitory effects of phosphoinositide 3-kinase inhibitors on platelet spreading. Although synthetic dipalmitoyl PtdIns-3,4-P2 and dipalmitoyl phosphatidylinositol 3',4', 5'-trisphosphate restored only partially platelet spreading, phosphatidylinositol 4',5'-bisphosphate (PtdIns-4,5-P2) was able to trigger full spreading of wortmannin-treated adherent platelets. Following 32P labeling of intact platelets, the recovery of [32P]PtdIns-4,5-P2 in anti-talin immunoprecipitates from adherent platelets was found to be decreased upon treatment by wortmannin. These results suggest that the lipid products of phosphoinositide 3-kinase are required but not sufficient for ADP-induced spreading of adherent platelets and that PtdIns-4,5-P2 could be a downstream messenger of this signaling pathway.