Carol Lenaghan

11β-Hydroxysteroid Dehydrogenase Type 1 Regulates Glucocorticoid-Induced Insulin Resistance in Skeletal Muscle

OBJECTIVE Glucocorticoid excess is characterized by increased adiposity, skeletal myopathy, and insulin resistance, but the precise molecular mechanisms are unknown. Within skeletal muscle, 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) converts cortisone (11-dehydrocorticosterone in rodents) to active cortisol (corticosterone in rodents). We aimed to determine the mechanisms underpinning glucocorticoid-induced insulin resistance in skeletal muscle and indentify how 11β-HSD1 inhibitors improve insulin sensitivity. RESEARCH DESIGN AND METHODS Rodent and human cell cultures, whole-tissue explants, and animal models were used to determine the impact of glucocorticoids and selective 11β-HSD1 inhibition upon insulin signaling and action. RESULTS Dexamethasone decreased insulin-stimulated glucose uptake, decreased IRS1 mRNA and protein expression, and increased inactivating pSer307 insulin receptor substrate (IRS)-1. 11β-HSD1 activity and expression were observed in human and rodent myotubes and muscle explants. Activity was predominantly oxo-reductase, generating active glucocorticoid. A1 (selective 11β-HSD1 inhibitor) abolished enzyme activity and blocked the increase in pSer307 IRS1 and reduction in total IRS1 protein after treatment with 11DHC but not corticosterone. In C57Bl6/J mice, the selective 11β-HSD1 inhibitor, A2, decreased fasting blood glucose levels and improved insulin sensitivity. In KK mice treated with A2, skeletal muscle pSer307 IRS1 decreased and pThr308 Akt/PKB increased. In addition, A2 decreased both lipogenic and lipolytic gene expression. CONCLUSIONS Prereceptor facilitation of glucocorticoid action via 11β-HSD1 increases pSer307 IRS1 and may be crucial in mediating insulin resistance in skeletal muscle. Selective 11β-HSD1 inhibition decreases pSer307 IRS1, increases pThr308 Akt/PKB, and decreases lipogenic and lipolytic gene expression that may represent an important mechanism underpinning their insulin-sensitizing action.

GPR120 (FFAR4) is preferentially expressed in pancreatic delta cells and regulates somatostatin secretion from murine islets of Langerhans

Aims/hypothesisThe NEFA-responsive G-protein coupled receptor 120 (GPR120) has been implicated in the regulation of inflammation, in the control of incretin secretion and as a predisposing factor influencing the development of type 2 diabetes by regulation of islet cell apoptosis. However, there is still considerable controversy about the tissue distribution of GPR120 and, in particular, it remains unclear which islet cell types express this molecule. In the present study, we have addressed this issue by constructing a Gpr120-knockout/β-galactosidase (LacZ) knock-in (KO/KI) mouse to examine the distribution and functional role of GPR120 in the endocrine pancreas.MethodsA KO/KI mouse was generated in which exon 1 of the Gpr120 gene (also known as Ffar4) was replaced in frame by LacZ, thereby allowing for regulated expression of β-galactosidase under the control of the endogenous GPR120 promoter. The distribution of GPR120 was inferred from expression studies detecting β-galactosidase activity and protein production. Islet hormone secretion was measured from isolated mouse islets treated with selective GPR120 agonists.Resultsβ-galactosidase activity was detected as a surrogate for GPR120 expression exclusively in a small population of islet endocrine cells located peripherally within the islet mantle. Immunofluorescence analysis revealed co-localisation with somatostatin suggesting that GPR120 is preferentially produced in islet delta cells. In confirmation of this, glucose-induced somatostatin secretion was inhibited by a range of selective GPR120 agonists. This response was lost in GPR120-knockout mice.Conclusions/interpretationThe results imply that GPR120 is selectively present within the delta cells of murine islets and that it regulates somatostatin secretion.

Lipid derivatives activate GPR119 and trigger GLP-1 secretion in primary murine L-cells

Highlights • GPR119, a putative fat sensor, is a potential target for metabolic disease.• KO of GPR119 in murine L-cells reduced GLP-1 response to fat in vivo.• Primary L-cells secreted GLP-1 in response to GPR119 agonists.• GPR119 agonists increased L-cell cAMP, with greatest efficacy in the colon.• Our data support the use of GPR119 agonists to raise GLP-1 levels.

Inhibition of PI3Kβ Signaling with AZD8186 Inhibits Growth of PTEN-Deficient Breast and Prostate Tumors Alone and in Combination with Docetaxel

Loss of PTEN protein results in upregulation of the PI3K/AKT pathway, which appears dependent on the PI3Kβ isoform. Inhibitors of PI3Kβ have potential to reduce growth of tumors in which loss of PTEN drives tumor progression. We have developed a small-molecule inhibitor of PI3Kβ and PI3Kδ (AZD8186) and assessed its antitumor activity across a panel of cell lines. We have then explored the antitumor effects as single agent and in combination with docetaxel in triple-negative breast (TNBC) and prostate cancer models. In vitro, AZD8186 inhibited growth of a range of cell lines. Sensitivity was associated with inhibition of the AKT pathway. Cells sensitive to AZD8186 (GI50 < 1 μmol/L) are enriched for, but not exclusively associated with, PTEN deficiency. In vivo, AZD8186 inhibits PI3K pathway biomarkers in prostate and TNBC tumors. Scheduling treatment with AZD8186 shows antitumor activity required only intermittent exposure, and that increased tumor control is achieved when AZD8186 is used in combination with docetaxel. AZD8186 is a potent inhibitor of PI3Kβ with activity against PI3Kδ signaling, and has potential to reduce growth of tumors dependent on dysregulated PTEN for growth. Moreover, AZD8186 can be combined with docetaxel, a chemotherapy commonly used to treat advanced TBNC and prostate tumors. The ability to schedule AZD8186 and maintain efficacy offers opportunity to combine AZD8186 more effectively with other drugs. Mol Cancer Ther; 14(1); 48–58. ©2014 AACR.

The cytoprotective effects of oleoylethanolamide in insulin-secreting cells do not require activation of GPR119

BACKGROUND AND PURPOSE β‐cells express a range of fatty acid‐responsive G protein‐coupled receptors, including GPR119, which regulates insulin secretion and is seen as a potential therapeutic target in type 2 diabetes. The long‐chain unsaturated fatty acid derivative oleoylethanolamide (OEA) is an endogenous agonist of GPR119 and, under certain conditions, some long‐chain unsaturated fatty acids can promote β‐cell cytoprotection. It is not known, however, if OEA is cytoprotective in β‐cells. The present study has examined this and determined whether GPR119 is involved.

Indazole-6-phenylcyclopropylcarboxylic Acids as Selective GPR120 Agonists with in Vivo Efficacy

GPR120 agonists have therapeutic potential for the treatment of diabetes, but few selective agonists have been reported. We identified an indazole-6-phenylcyclopropylcarboxylic acid series of GPR120 agonists and conducted SAR studies to optimize GPR120 potency. Furthermore, we identified a (S,S)-cyclopropylcarboxylic acid structural motif which gave selectivity against GPR40. Good oral exposure was obtained with some compounds displaying unexpected high CNS penetration. Increased MDCK efflux was utilized to identify compounds such as 33 with lower CNS penetration, and activity in oral glucose tolerance studies was demonstrated. Differential activity was observed in GPR120 null and wild-type mice indicating that this effect operates through a mechanism involving GPR120 agonism.

Inhibiting PI3Kβ with AZD8186 Regulates Key Metabolic Pathways in PTEN-Null Tumors

Purpose: PTEN-null tumors become dependent on the PI3Kβ isoform and can be targeted by molecules such as the selective PI3Kβ inhibitor AZD8186. However, beyond the modulation of the canonical PI3K pathway, the consequences of inhibiting PI3Kβ are poorly defined. Experimental Design: To determine the broader impact of AZD8186 in PTEN-null tumors, we performed a genome-wide RNA-seq analysis of PTEN-null triple-negative breast tumor xenografts treated with AZD8186. Mechanistic consequences of AZD8186 treatment were examined across a number of PTEN-null cell lines and tumor models. Results: AZD8186 treatment resulted in modification of transcript and protein biomarkers associated with cell metabolism. We observed downregulation of cholesterol biosynthesis genes and upregulation of markers associated with metabolic stress. Downregulation of cholesterol biosynthesis proteins, such as HMGCS1, occurred in PTEN-null cell lines and tumor xenografts sensitive to AZD8186. Therapeutic inhibition of PI3Kβ also upregulated PDHK4 and increased PDH phosphorylation, indicative of reduced carbon flux into the TCA cycle. Consistent with this, metabolomic analysis revealed a number of changes in key carbon pathways, nucleotide, and amino acid biosynthesis. Conclusions: This study identifies novel mechanistic biomarkers of PI3Kβ inhibition in PTEN-null tumors supporting the concept that targeting PI3Kβ may exploit a metabolic dependency that contributes to therapeutic benefit in inducing cell stress. Considering these additional pathways will guide biomarker and combination strategies for this class of agents. Clin Cancer Res; 23(24); 7584–95. ©2017 AACR.

Abstract 2228: Phosphatidylinositol-4-kinase - Potent and selective inhibitors of PI4Kα and PI4Kβ.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Phosphatidylinositol (PI) is a phospholipid that resides primarily on the cytosolic surface of cell membranes. PI can be phosphorylated to generate seven different phosphatidylinositol phosphates (PIPs), all of which have distinct biological activities.1 A major first step in the production of these PIPs is the conversion of PI into phosphatidylinositol-4-phosphate (PI4P) by PI4 kinase.2 Here we describe the identification of inhibitors of PI4 kinase via targeted screening of a kinase subset. This exercise has delivered inhibitors that are potent inhibitors of PI4 kinase (pIC50 >8), which are selective the α- or the β-subtypes and do not inhibit related enzymes on the PI pathway (PI3 kinase pIC50 <5 or PIP5 kinase pIC50 <4) and also exhibit good broader kinase selectivity. The effect of these useful probe compounds on cellular phosphatidylinositol-4,5-diphosphate and subsequent downstream markers will be described along with the comparison of these effects with the corresponding siRNA. 1. G. Di Paolo, P. De Camilli, Phosphoinositides in cell regulation and membrane dynamics. Nature 2006, 443, 651-657.2. T. Sasaki, S. Takasuga, J. Sasaki, S. Kofuji, S. Eguchi, M. Yamazaki, A. Suzuki, Mammalian phosphoinositide kinases and phosphatases. Progress in lipid research, 2009, 48, 307-343. Citation Format: Michael J. Waring, Darren Cross, David Andrews, Vikki Flemington, Carol Lenaghan, Jennifer McKelvie, Sarita Maman, Piotr Raubo, Graeme Robb, James Smith, Martin Swarbrick. Phosphatidylinositol-4-kinase - Potent and selective inhibitors of PI4Kα and PI4Kβ. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2228. doi:10.1158/1538-7445.AM2013-2228

Abstract 4249: The Pi3Kβ/δ inhibitor AZD8186 has potential to treat tumours in combination with key signalling pathway inhibitors

AZD8186 inhibits Pi3K isoforms Pi3Kβ and δ, with selectivity over Pi3Kα and γ. In solid tumours Pi3Kβ drives tumour growth when the tumour suppressor PTEN is deleted, mutated or downregulated. It also mediates signals from specific GPCR receptors. Pi3Kδ signals downstream of the B-cell receptor, creating potential for targeted treatment of haematological malignancies such as CLL, MCL & indolent NHL and possibly DLBCL. AZD8186 is differentiated from many other agents that target Pi3K family members as it isn9t likely to impact glucose control. AZD8186 has single agent activity in a range of models, although maximal benefit is anticipated when used in combination. Loss of PTEN mediated control, and hence dependency on PI3Kβ occurs in many solid tumour types, and is altered in up to 40-50% of tumours in some individual disease states. Commonly PTEN dysregulation is associated with other activation of other signaling pathways. To explore this we have combined AZD8186 with a number of different agents. In HCC70 (triple negative breast cancer) and PC3 (prostate cancer) xenografts combination of AZD8186 (25mg/kg bid) with single dose docetaxel (15mg/kg) gives >90% tumour growth inhibition (TGI), compared to 40-50% with docetaxel alone. AZD8186 also combines with other targeted agents. In HCC70, AZD8186 (25mg/kg bid) combined with selumetinib (10mg/kg) gave 94% TGI compared to 66%, and 47% with each single agent. In combination with AZD2014 (mTORC1/2 inhibitor) (15mg/kg qd) in HCC70 xenografts AZD8186 (25mg/kg bid) gave regressions (-23%) compared to TGI of 87% and 77% for each agent alone. In 786-0 (renal cancer) xenografts AZD8186 (12.5mg/kg bid) and AZD2014 (15mg/kg qd) gave regression of -82% compared to TGI of 33% and regression of -39% with each agent alone. This data establishes the potential for AZD8186 to be used in combination with a number of different agents including the ability to customise dose and schedule to optimise both tolerability as well as anti-tumour 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 tumour types. Citation Format: Simon T. Barry, Kathryn Cronin, Marie Cumberbatch, Rebecca Ellston, Emily Foster, Urs Hancox, Lyndsey Hanson, Liz Harrington, Carol Lenaghan, Stefan Symeonides, Cath Trigwell, Lara Ward. The Pi3Kβ/δ inhibitor AZD8186 has potential to treat tumours in combination with key signalling pathway inhibitors. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4249. doi:10.1158/1538-7445.AM2014-4249