bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract A22: Identification of a novel protein that blocks the Rag-Ragulator interaction and inhibits mTORC1
Authors: Schweitzer Lawrence D. , Sabatini David M. 
Published: October 2015

Abstract
mTORC1 controls key pathways that maintain cell viability, including translation, ribosome biogenesis and autophagy. Amino acids are a crucial input to mTORC1 activation, resulting in the recruitment of the complex to the surface of lysosomal membrane. The kinase activity of mTORC1 is subsequently turned on at the lysosome downstream of growth factor signaling. mTORC1 is brought to the lysosome by the Rag GTPases, which are tethered to the membrane by their lysosomal scaffold and guanine nucleotide exchange factor, Ragulator. We have identified a novel regulator of mTORC1 activity that inhibits mTORC1 through binding to the Ragulator. This binding prevents the interaction between the Ragulator and its only known substrate, the Rag GTPases, both in cells and in vitro. This disruption of the Rag-Ragulator interaction results in impaired mTORC1 activation by amino acids. However, the novel Ragulator-interacting protein is not regulated by amino acids; it behaves as a link that integrates another signal transduction pathway that inhibits mTORC1 regardless of the presence of amino acids.
Citation Format: Lawrence D. Schweitzer, David M. Sabatini. Identification of a novel protein that blocks the Rag-Ragulator interaction and inhibits mTORC1. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr A22.
Abstract A23: Differentiation of PI3K/Akt/mTOR inhibition in cancer models using dual dissociative TORC1/TORC2 (P529), single dissociative TORC1 (rapalogs) and catalytic inhibitors (PI3K/Akt, PI3K/mTOR)
Authors: Sherris David , Dennis Philip A. , Wilson Willie , Kawabata Shigeru , Yu Chunrong , Gravina Giovanni Luca , Mancini Andrea , Festuccia Claudio 
Published: October 2015

Abstract
P529 is a first-in-class, allosteric, small molecule, dual dissociative inhibitor of the TORC1 and TORC2 protein complexes within the PI3K/Akt/mTOR pathway. P529 has been previously shown to cause the rapid dissociation of the TORC1 and TORC2 complexes both in vitro and in vivo tumor xenograft models. Other PI3K inhibitors include rapalogs which cause the dissociation of the TORC1 complex and, PI3K/mTOR and PI3K/Akt inhibitors aimed at protein kinase catalytic site inhibition. Although these inhibitors have shown some utility in inhibiting cancer growth, they have deficiencies inherent to their mechanism of action. Rapalogs have been shown to stimulate the PI3K pathway through the induction of the IRS-1 negative feedback loop. Although mTOR resides in both TORC1 and TORC2, catalytic inhibition of mTOR does not dissociate both complexes allowing other proteins within the complexes to retain and exert signalling activity. Hence they are not true dual TORC1/TORC2 inhibitors, but only mTOR inhibitors. Here we show comparison of P529 with rapalogs and the catalytic inhibitors PI3K/mTOR and PI3K/Akt delineating activity in prostate, lung, glioblastoma and hepatic tumor evaluating cell survival, phosphoprotein PI3K signaling (IC50), CT scanning, tumor volume and growth arrest in cellular models and murine xenografts, showing superiority of allosteric dual TORC1/TORC2 dissociative inhibition. Furthermore, in addition to evaluation in cancer treatment models, data will be presented showing activity in cancer prevention using the mutant EGFR (L858R/T790M) transgene lung expression model.
Citation Format: David Sherris, Philip A. Dennis, Willie Wilson, III, Shigeru Kawabata, Chunrong Yu, Giovanni Luca Gravina, Andrea Mancini, Claudio Festuccia. Differentiation of PI3K/Akt/mTOR inhibition in cancer models using dual dissociative TORC1/TORC2 (P529), single dissociative TORC1 (rapalogs) and catalytic inhibitors (PI3K/Akt, PI3K/mTOR). [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr A23.
Abstract A24: Comprehensive PI3K pathway inhibition through combination of the PI3Kβ/δ inhibitor AZD8186 and the mTORC1/2 inhibitor AZD2014 drives tumor regression in vivo
Authors: Hancox Urs , Polanska Urszula , Hanson Lyndsay , Ellston Rebecca , Maynard Julia , Kraus Manfred , Curwen jon , Klinowska Teresa , Ward Lara , Cruzalegui Francisco , Green Stephen , Symeonides Stefan , Cronin Kathryn , Barry Simon 
Published: October 2015

Abstract
AZD8186 inhibits the PI3K isoforms PI3Kβ and δ In solid tumors when the tumor suppressor PTEN is deleted, mutated or downregulated PI3Kβ becomes a key driver of tumor cell growths. In hematological tumors such as DLBCL PTEN is down-regulated, moreover PI3Kδ is important in signaling from the B-cell receptor, creating potential for targeted treatment of hematological malignancies. AZD8186 has single agent activity in a range of pre-clinical models representative of different tumor types. However efficacy of agents in the PI3K pathway are anticipated to be limited by compensatory PI3K isoform activation or relief of feedback loops. As a result it is likely that maximal benefit will be seen when combining different agents that target the PI3K pathway. Unlike other inhibitors of the PI3K pathway AZD8186 does not affect peripheral glucose levels. However AZD8186 specifically modulates tumor FDG uptake in the PTEN null tumor model 786-0. This is associated with tumor specific modulation of the PI3K pathway biomarkers. Therefore in PTEN null tumors AZD8186 can be combined with other PI3K pathway inhibitors to give increased pathway suppression without increasing normal tissue toxicity. To test this AZD8186 has been combined with the mTORC1/2 inhibitor AZD2014 in a number of different PTEN null tumors. The combination increased reduction in tumor growth, and even induced tumor regression. This is associated with increase depth or duration of pathway suppression. Interestingly tumor regressions can be achieved with intermittent of both AZD8186 and AZD2014, implying that acute complete pathway suppression is sufficient to drive the anti-tumor effect. This data establishes the potential for AZD8186 to be used in combination with a mTOR inhibitors with the ability to customize dose and schedule to optimize both tolerability as well as anti-tumor effects. Further exploration of the combination opportunities for AZD8186 with other molecular targeted agents would inform on the potential for inhibitors of PI3Kβ and δ to give benefit in different tumor types.
Citation Format: Urs Hancox, Urszula Polanska, Lyndsay Hanson, Rebecca Ellston, Julia Maynard, Manfred Kraus, jon Curwen, Teresa Klinowska, Lara Ward, Francisco Cruzalegui, Stephen Green, Stefan Symeonides, Kathryn Cronin, Simon Barry. Comprehensive PI3K pathway inhibition through combination of the PI3Kβ/δ inhibitor AZD8186 and the mTORC1/2 inhibitor AZD2014 drives tumor regression in vivo. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr A24.
Abstract A42: Increased Akt3 expression as a resistance mechanism to targeted therapy
Authors: Chin Y Rebecca , Toker Alex 
Published: October 2015

Abstract
Resistance to targeted therapy poses a major challenge for successful treatment of cancers. Despite a number of drugs targeting the PI 3-K/Akt pathway are in clinical development, mechanisms of resistance to drugs targeting this pathway have not been studied extensively. To determine how breast cancer cells develop resistance to Akt inhibitors (Akti), we generated Akti-resistant lines using dose escalation regimens with pan-Akt inhibitors (ATP-competitive: GDC0068, GSK690693; Allosteric: MK2206). Interestingly, in multiple Akti-resistant breast cancer lines, we observed a robust increase in the protein expression of Akt3, but not Akt1 or Akt2. We were intrigued by this observation, as we have recently demonstrated that Akt3 has a predominant function in regulating growth of triple negative breast cancer cells in three-dimensional spheroids and in xenograft models. The increased expression of Akt3 in Akti-resistant cells occurs via a genetic event, since the levels of Akt3 remain elevated after 3 weeks of Akt inhibitor removal. Moreover, upon Akt inhibitor removal in resistant lines, cells remain resistant to Akt inhibition. The enhanced Akt3 expression is observed in both luminal and basal-like triple-negative breast cancer resistant lines. Importantly, knockdown of Akt3, but not Akt1 or Akt2, results in re-sensitization of resistant cells to Akti. Mechanistically, using anti-phosphotyrosine receptor antibody array (RTK array), we observed increased phosphorylation of several RTKs in resistant cells, including EGFR, Her2, and ROR1. Akt3 knockdown in resistant cells results in reduction of pEGFR, pHer3 and pHer2, suggesting that Akt3 plays a role in the regulation of multiple RTKs in resistant cells. Epithelial-mesenchymal transition (EMT) is implicated in therapeutic resistance of cancers. Interestingly, several of our resistant lines display EMT properties including downregulation of E-Cadherin, and upregulation of N-Cadherin as well as Vimentin. We propose that enhanced Akt3 expression is a general mechanism by which breast cancer cells acquire resistance to Akti targeted therapy. Current efforts are aimed at investigating the mechanistic basis for Akt3-mediated resistance, and demonstrating the physiological relevance of these findings in clinical samples as well as in mouse models. The role of Akt3 in regulating EMT during establishment of resistance will also be explored. These studies will provide insights into molecular mechanisms of therapeutic resistance to drugs targeting the PI 3-K/Akt pathway, as well as information for designing combination strategies and next generation therapy.
Citation Format: Y Rebecca Chin, Alex Toker. Increased Akt3 expression as a resistance mechanism to targeted therapy. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr A42.
Abstract A56: A dual PI3K-mTOR inhibitor induced cardiac hypertrophy in mice: Role of the insulin signaling
Authors: Onufrak Jillian , Yang Yongayo , Lee Juyong , Fuseler John , Sun Maoyun , Sasi Sharath , McDonald J. Tyson , Hlatky Lynn , Price Robert L. , Carrozza Joseph , Goukassian David , Borg Thomas K. , Morgan James P. , Yan Xinhua 
Published: October 2015

Abstract
Studies from us and others showed that mice with cardiomyocyte-specific overexpression of a dominant negative PI3Kp110α had smaller hearts but maintained normal cardiac function. Yet, these mice developed systolic heart failure in the presence of cardiac stress, such as chemotherapy drug doxorubicin and aortic stenosis. Currently, drugs targeting the PI3K pathway are being tested in clinical trials for cancer therapy. Therefore, it is important to assess the cardiac effects of pharmacological inhibition of this pathway. Here, we report that a dual PI3K-mTOR inhibitor, BEZ235 (BEZ), induced cardiac hypertrophy and subsequent heart failure in mice when it was used alone or in combination with doxorubicin. This effect of BEZ was associated with increased hepatic gluconeogenesis, hyperglycemia, hyperinsulinemia and increased activation of the IGFR/insulin receptor (IR) in the heart. In isolated cardiomyocyte culture, BEZ induced feedback activation of IGFR/IR, but this effect was negligible compared to the IGFR/IR activation in the presence of insulin. Injections of insulin in mice lowered blood glucose, improved glucose and pyruvate tolerance but further increased the activation of IGFR/IR in the heart and aggravated BEZ-induced cardiac dysfunction; whereas OSI-906, an IGFR/IR inhibitor, alleviated this cardiac dysfunction. In addition, low dose Metformin significantly prolonged survival and improved cardiac function in BEZ-treated mice. Taken together, these results identified hyperinsulinemia, a systematic effect of the drug, as one of the mechanisms of BEZ-induced cardiac hypertrophy, arguing animal studies are indispensable for evaluating drug toxicity. They also suggest that Metformin but not insulin should be considered for controlling hyperglycemia and preventing the cardiac side effects that may be caused by PI3K pathway inhibitors in clinic.
Citation Format: Jillian Onufrak, Yongayo Yang, Juyong Lee, John Fuseler, Maoyun Sun, Sharath Sasi, J. Tyson McDonald, Lynn Hlatky, Robert L. Price, Joseph Carrozza, David Goukassian, Thomas K. Borg, James P. Morgan, Xinhua Yan. A dual PI3K-mTOR inhibitor induced cardiac hypertrophy in mice: Role of the insulin signaling. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr A56.
Abstract B08: Kicking the addictions: Therapeutic strategies for NSCLC
Authors: Solitro Abigail R. , MacKeigan Jeffrey P. 
Published: October 2015

Abstract
The discovery of cancer cells' dependency on the self-cannibalization program autophagy has spawned the investigation of its efficacy as a therapeutic target. However, the use of lysomotropic agents to inhibit autophagy as single-agent therapeutics has proven less than optimal. Recent investigations into the design of sequential treatment strategies targeting pathways preferentially used by cancer cells have shown promise. This novel spin on personalized medicine seeks to exploit the kinetics and mechanisms by which cancer cells become dependent on proliferation and survival pathways. Oncogenic KRAS-driven non-small cell lung cancer (NSCLC) is known to depend on mTORC1-driven growth and autophagy for survival; such autophagy addiction is beneficial to cancer cells, as it eliminates the need for exogenous nutrient supplies. We aim to elucidate the mechanism and kinetics of autophagy addiction in NSCLC, in order to design sequential treatment strategies against this disease.
Citation Format: Abigail R. Solitro, Jeffrey P. MacKeigan. Kicking the addictions: Therapeutic strategies for NSCLC. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr B08.
Abstract B11: PI3-kinase inhibition forestalls the development of drug resistance in BRAFV600E/PTENNull melanoma
Authors: Deuker Marian M. , Durban Victoria Marsh , Phillips Wayne , McMahon Martin 
Published: October 2015

Abstract
The phosphatidylinositol 3′-kinase (PI3K) signaling pathway is frequently dysregulated in BRAF mutated melanomas and serves to promote the growth of tumors initiated by expression of BRAFV600E. The most prevalent mechanism of PI3K pathway activation occurs via silencing expression of the phosphatase and tensin homolog (PTEN) tumor suppressor, but mutational activation of PIK3CA, encoding the 110kDa catalytic subunit of PI3□-kinase-α, has also been observed at low frequency. However, the PI3K catalytic isoform dependence of BRAF mutated melanoma remains poorly understood, as does the differential isoform dependence imbued by discrete nodes of PI3K pathway dysregulation. To characterize the PI3K isoform dependence of BRAFV600E/PTENNull as well as BRAFV600E/PIK3CAH1047R melanoma, we administered a panel of isoform-selective PI3K inhibitors to cultured melanoma cells and to genetically engineered mouse (GEM) models of melanoma of both genotypes. These studies revealed that, while BRAFV600E/PIK3CAH1047R melanoma was sensitive to p110α-selective inhibition, inhibition of BRAFV600E/PTENNull melanoma cell proliferation required combined blockade of p110α (PIK3CA), p110δ (PIK3CD) and p110γ (PIK3CG). Moreover, in GEM models of BRAFV600E/PIK3CAH1047R or BRAFV600E/PTENNull melanoma, isoform-selective PI3K inhibition elicited only a cytostatic effect as monotherapy, but enhanced melanoma regression in response to BRAFV600E→MEK→ ERK pathway-targeted inhibition. Most interestingly, treatment with GDC0032, a p110β-sparing PI3K inhibitor, forestalled the onset of MEK inhibitor (GDC-973, cobimetinib) resistant disease in the BRAFV600E/PTENNull GEM model of melanoma. Together, these data suggest that PIK3CA mutational status may be used to select for melanoma patients that will respond to a p110α-selective inhibitor. By contrast, PTENNull melanoma patients will require a p110β sparing pan-class I PI3K inhibitor. Moreover, although monotherapy PI3K inhibition did not elicit dramatic tumor regression, blockade of this pathway may be a useful strategy to extend the duration of response to BRAFV600E pathway-targeted therapy.
Citation Format: Marian M. Deuker, Victoria Marsh Durban, Wayne Phillips, Martin McMahon. PI3-kinase inhibition forestalls the development of drug resistance in BRAFV600E/PTENNull melanoma. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr B11.
Abstract B13: Regulation of Akt activity, cell proliferation, and viability in ovarian cancer cells by calcium/calmodulin-dependent protein kinase kinase 2
Authors: Gocher Angela M. , Franke Thomas F. , Azabdaftari Gissou , Karacosta Loukia G. , Edelman Arthur M. 
Published: October 2015

Abstract
Calcium/Calmodulin-dependent protein kinase kinase 2 (CaMKK2) has been implicated in the regulation of G1/S phase cell cycle progression in prostate and breast cancer but has not been studied in ovarian cancer (OvCa). We report here the following. CaMKK2 is abundantly expressed in high grade serous papillary cystadenocarcinoma. Knockdown (KD) of CaMKK2 expression using RNAi in OVCAR-3 OvCa cells resulted in slowing of cell growth, decreased cyclin D1 protein and mRNA, decreased phosphorylation of the tumor suppressor protein Rb at Ser807/811 and decreased DNA synthesis, indicating an arrest at the G1/S interface. CaMKK2 KD decreased cell viability, increased PARP cleavage and increased Caspase-3/7 activity suggesting apoptosis induction by CaMKK2 loss. CaMKK2 KD decreased p-Akt at Thr308 to a similar extent (59.3%) as that of PDK1 KD (50.4%) in OVCAR-3 cells. Combined CaMKK2 and PDK1 KDs led to an additive (80.7%) decrease in p-Akt suggesting that CaMKK2 regulates Akt activating phosphorylation independently of the canonical-PDK1 pathway. Additive effects of combined PDK1/CaMKK2 KD on p-Akt Thr308 in SKOV-3 OvCa cells were also obtained. The ability of baculovirus expressed and purified Akt to phosphorylate a specific peptide substrate was enhanced at least 9-fold by purified CaMKK2, whereas kinase activity of Akt T308A/S473A was not increased by CaMKK2. Direct phosphorylation of baculovirus expressed Akt at Thr308 by CaMKK2 was confirmed by Western blotting using Akt phospho-specific antibodies. Altogether these data show that CaMKK2 regulates cell growth and viability in OvCa cells and directly phosphorylates Akt to promote its activity via a non-PDK1-dependent pathway. These data indicate that CaMKK2 may be a novel therapeutic target for OvCa in combination with a PI3K inhibitor.
Citation Format: Angela M. Gocher, Thomas F. Franke, Gissou Azabdaftari, Loukia G. Karacosta, Arthur M. Edelman. Regulation of Akt activity, cell proliferation, and viability in ovarian cancer cells by calcium/calmodulin-dependent protein kinase kinase 2. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr B13.
Abstract B20: Lysosomal interaction of Akt with Phafin2: A critical step in the induction of autophagy
Authors: Noguchi Masayuki , Suizu Futoshi , Lennikov-Matsuda Mami , Jyoti Bala , Ohba Yusuke , Hirata Noriyuki 
Published: October 2015

Abstract
Autophagy is an evolutionarily conserved mechanism for the gross disposal of intracellular proteins in mammalian cells and dysfunction in this pathway has been associated with human disease. Although the serine threonine kinase Akt is suggested to play a role in this process, little is known about the molecular mechanisms by which Akt induces autophagy. Using a yeast two-hybrid screen, Phafin2 (EAPF or PLEKHF2), a lysosomal protein with a unique structure of N-terminal PH (pleckstrin homology) domain and C-terminal FYVE (Fab 1, YOTB, Vac 1, and EEA1) domain was found to interact with Akt. A sucrose gradient fractionation experiment revealed that both Akt and Phafin2 co-existed in the same lysosome enriched fraction after autophagy induction. Confocal microscopic analysis and BiFC analysis demonstrated that both Akt and Phafin2 accumulate in the lysosome after induction of autophagy. BiFC analysis using PtdIns (3)P interaction defective mutant of Phafin2 demonstrated that lysosomal accumulation of the Akt-Phafin2 complex and subsequent induction of autophagy were lysosomal PtdIns (3)P dependent events. Furthermore, in murine macrophages, both Akt and Phafin2 were required for digestion of fluorescent bacteria and/or LPS-induced autophagy. Furthermore, overexpression of wild-type Phafin2, but not PtdIns (3)P interaction defective mutant Phafin2, suppressed oncogenic potency in Ras (or Myr-Akt, or TCL1)-induced colony transformation assays. Taken together, these findings establish that lysosomal accumulation of Akt and Phafin2 is a critical step in the induction of autophagy via an interaction with PtdIns (3)P.
Citation Format: Masayuki Noguchi, Futoshi Suizu, Mami Lennikov-Matsuda, Bala Jyoti, Yusuke Ohba, Noriyuki Hirata. Lysosomal interaction of Akt with Phafin2: A critical step in the induction of autophagy. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr B20.