Burkhard Göke - Academia.edu (original) (raw)

Papers by Burkhard Göke

Islets

The members of the Suppressor of Cytokine Signaling (SOCS) protein family mainly modulate the Jan... more The members of the Suppressor of Cytokine Signaling (SOCS) protein family mainly modulate the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway. SOCS-1 and SOCS-3 have already been shown to influence growth and apoptosis of pancreatic beta cells. We hypothesized that SOCS-2, which is expressed in pancreatic islets, also contributes to β-cell physiology. We tested this hypothesis in vivo in SOCS-2-/- knockout mice and in vitro in Ins-1E rat insulinoma cells. We found that SOCS-2-/- mice have normal islet insulin secretion and unchanged glucose and insulin tolerance compared to wildtype controls. SOCS-2-/- are bigger than wildtype mice but body weight-corrected β-cell mass and islet morphology were normal. Growth hormone-induced proliferation of Ins-1E cells was not affected by either siRNA-mediated SOCS-2 knockdown or stable SOCS-2 overexpression. Interleukin-1β mediated cell death in vitro was unchanged after SOCS-2 knockdown. Similarly, autoimmune d...

Journal of Translational Medicine, Feb 25, 2015

Oncotarget, Jan 28, 2016

DNA repair defects due to detrimental BRCA2-mutations confer increased susceptibility towards DNA... more DNA repair defects due to detrimental BRCA2-mutations confer increased susceptibility towards DNA interstrand-crosslinking (ICL) agents and define patient subpopulations for individualized genotype-based cancer therapy. However, due to the side effects of these drugs, there is a need to identify additional agents, which could be used alone or in combination with ICL-agents. Therefore, we investigated whether BRCA2-mutations might also increase the sensitivity towards TRAIL-receptors (TRAIL-R)-targeting compounds. Two independent model systems were applied: a BRCA2 gene knockout and a BRCA2 gene complementation model. The effects of TRAIL-R-targeting compounds and ICL-agents on cell viability, apoptosis and cell cycle distribution were compared in BRCA2-proficient versus-deficient cancer cells in vitro. In addition, the effects of the TRAIL-R2-targeting antibody LBY135 were assessed in vivo using a murine tumor xenograft model. BRCA2-deficient cancer cells displayed an increased sens...

PloS one, 2015

The mTORC1-inhibitor everolimus shows limited efficacy in treating patients with gastro-entero-pa... more The mTORC1-inhibitor everolimus shows limited efficacy in treating patients with gastro-entero-pancreatic or pulmonary neuroendocrine tumors (NETs), and poor outcome in patients with malignant pheochromocytoma or hepatic carcinoma. We speculated that any effect may be enhanced by antogonising other signaling pathways. Therefore, we tested the effect of lovastatin-known to inhibit both ERK and AKT signaling-and everolimus, separately and in combination, on cell viability and signaling pathways in human midgut (GOT), pancreatic (BON1), and pulmonary (H727) NET, hepatocellular carcinoma (HepG2, Huh7), and mouse pheochromocytoma (MPC, MTT) cell lines. Lovastatin and everolimus separately significantly reduced cell viability in H727, HepG2, Huh7, MPC and MTT cells at clinically relevant doses (P ≤ 0.05). However, high doses of lovastatin were necessary to affect GOT or BON1 cell viability. Clinically relevant doses of both drugs showed additive anti-tumor effects in H727, HepG2, Huh7, MP...

American journal of physiology. Endocrinology and metabolism, 2002

Impaired glucose tolerance (IGT) and non-insulin-dependent diabetes mellitus (NIDDM) are associat... more Impaired glucose tolerance (IGT) and non-insulin-dependent diabetes mellitus (NIDDM) are associated with an impaired ability of the beta-cell to sense and respond to small changes in plasma glucose. The aim of this study was to establish whether acute hyperglycemia per se plays a role in inducing this defect in beta-cell response. Seven healthy volunteers with no family history of NIDDM were studied on two occasions during a 12-h oscillatory glucose infusion with a periodicity of 144 min. Once, low-dose glucose was infused at a mean rate of 6 mg x kg(-1) x min(-1) and amplitude 33% above and below the mean rate, and, once, high-dose glucose was infused at 12 mg x kg(-1) x min(-1) and amplitude 16% above and below the mean rate. Mean glucose levels were significantly higher during the high-dose compared with the low-dose glucose infusion [9.5 +/- 0.8 vs. 6.8 +/- 0.2 mM (P < 0.01)], resulting in increased mean insulin secretion rates [ISRs; 469.1 +/- 43.8 vs. 268.4 +/- 29 pmol/min ...

Molecular Endocrinology, 2001

Activation of the G-protein-coupled receptor for glucose-dependent insulinotropic polypeptide fac... more Activation of the G-protein-coupled receptor for glucose-dependent insulinotropic polypeptide facilitates insulin-release from pancreatic ␤-cells. In the present study, we examined whether glucosedependent insulinotropic polypeptide also acts as a growth factor for the ␤-cell line INS-1. Here, we show that glucose-dependent insulinotropic polypeptide induced cellular proliferation synergistically with glucose between 2.5 mM and 15 mM by pleiotropic activation of signaling pathways. Glucose-dependent insulinotropic polypeptide stimulated the signaling modules of PKA/cAMP regulatory element binder, MAPK, and PI3K/protein kinase B in a glucose-and dose-dependent manner. Janus kinase 2 and signal transducer and activators of transcription 5/6 pathways were not stimulated by glucose-dependent insulinotropic polypeptide. Activation of PI3K by glucose-dependent insulinotropic polypeptide and glucose was associated with insulin receptor substrate isoforms insulin receptor substrate-2 and growth factor bound-2 associated binder-1 and PI3K isoforms p85␣, p110␣, p110␤, and p110␥. Downstream of PI3K, glucose-dependent insulinotropic polypeptide-stimulated protein kinase B␣ and protein kinase B␤ isoforms and phosphorylated glycogen synthase kinase-3, forkhead transcription factor FKHR, and p70 S6K. These data indicate that glucose-dependent insulinotropic polypeptide functions synergistically with glucose as a pleiotropic growth factor for insulin-producing ␤-cells, which may play a role for metabolic adaptations of insulin-producing cells during type II diabetes.

Journal of Nuclear Medicine, 2012

The Journal of Clinical Endocrinology & Metabolism, 2010

International Journal of Clinical Practice, 2010

Saxagliptin is non-inferior to glipizide in patients with type 2 diabetes mellitus inadequately c... more Saxagliptin is non-inferior to glipizide in patients with type 2 diabetes mellitus inadequately controlled on metformin alone: a 52-week randomised controlled trial <> Saxagliptin non-inferior to glipizide as add-on therapy to metformin <>

FEBS Letters, 1990

Amylin, a 37 amino acid C‐terminal amidated peptide is an integral part of secretory granules of ... more Amylin, a 37 amino acid C‐terminal amidated peptide is an integral part of secretory granules of pancreatic β‐cells. Utilizing a specific radioimmunoassay system we demonstrate in the present study a cosecretion of amylin and insulin from the isolated rat pancreas. The secretion pattern of both peptides during glucose or glucose plus arginine stimulation is identical. The molar ratio of amylin amounts to 10% of that of insulin. The biological significance of amylin is still unknown, but a paracrine/endocrine role in glucose homeostasis is speculated.

FEBS Letters, 1992

Glucagon‐like peptide‐1 (7–36)amide (GLP‐1 (7–36)amide) represents a physiologically important in... more Glucagon‐like peptide‐1 (7–36)amide (GLP‐1 (7–36)amide) represents a physiologically important incretin in mammals including man. Receptors for GLP‐1 (7–36)amide have been described in RINm5F cells. We have solubilized active GLP‐1 (7–36)amide receptors from RINm5F cell membranes utilizing the detergents octyl‐β‐glucoside and CHAPS; Triton X‐100 and Lubrol PX were ineffective. Binding of radiolabeled GLP‐1(7–36)amide to the solubilized receptor was inhibited conentration‐dependently by addition of unlabeled peptide. Scatchard analysis of binding data revealed a single class of binding sites with K a= 0.26 ± 0.03 nM and B max= 65.4 ± 21.24 fmol/mg of protein for the membrane‐bound receptor and K a= 22.54 ± 4.42 μM and B max= 3.9 ± 0.79 pmol/mg of protein for the solubilized receptor. The binding of the radiolabel to the solubilized receptor was dependent both on the concentrations of mono‐ and divalent cations and the protein/detergent ratio in the incubation buffer. The membrane bou...

FEBS Letters, 1992

This study was designed to search for the expression of the small-moleeular.wei ,l~ht GTP-binding... more This study was designed to search for the expression of the small-moleeular.wei ,l~ht GTP-binding protein rab3a in endocrine pancreatic cell lines. Total RNA was isolated from fi~e different cell lines (RINmSF, RIN 104836, fl-TCI, HIT-15. and INRI-G9) and from whole rat brain. The expression of rab3a was analyzed by Northern blots. Similar as in brain two transcripts of 1300 and 1800 bp were detected in RIN.e~IIs at low stringency conditions with the predominant signal at 1300 bp. At high stringency the stronger signal was at 1800 bp. When a 300 bp Pstl fmlgnent derived from the coding region ofrab3a was utilized as probe the 1800 bp signal was predominant under each condition. Only a faint band at 1800 bp occurred in preparations from ffrCl.cells and no signal at all was found in HIT-I 5 and INRI-Gg-celIs. In conclusion, rab3a is expressed in rat insulln-releashag insulinoma.derived RIN.eells with a specific 1800 bp transcription product.

FEBS Letters, 1991

125I‐labelled GLP‐I(7–36)amide was cross‐linked to a specific binding protein in rat lung membran... more 125I‐labelled GLP‐I(7–36)amide was cross‐linked to a specific binding protein in rat lung membranes using disuccinimidyl suberate. A single radio‐labelled band at M r 66000 was identified by SDS‐PAGE after solubilization of the ligand‐binding protein complex which is consistent with the presence of a single class of binding sites on rat lung membranes. The band was undetectable when 1 μmol/1 GLP‐I(7–36)amide was included in the binding assay. No change in the mobility of the band was observed under reducing conditions suggesting that the binding protein in the receptor is not part of a larger disulphide‐liked protein. The intensity of the radiolabelled protein band was reduced when the incubation with 125I‐labelled GLP‐I(7–36)amide was carried out in the presence of guanine nucleotides suggesting that the GLP‐I(7–36)amide receptor is coupled to the adenylate cyclase system.

Endocrine Related Cancer, 2011

The tumour-selective death receptor ligand tumour necrosis factor-related apoptosis-inducing liga... more The tumour-selective death receptor ligand tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising agent for the treatment of human cancer. However, many tumours have evolved mechanisms to resist TRAIL-induced apoptosis. A number of studies have demonstrated that aberrant PI(3)K-Akt-mTOR survival signalling may confer TRAIL resistance by altering the balance between pro-and anti-apoptotic proteins. Here, we show that neuroendocrine tumour (NET) cell lines of heterogeneous origin exhibit a range of TRAIL sensitivities and that TRAIL sensitivity correlates with the expression of FLIP S , caspase-8, and Bcl-2. Neither single mTOR inhibition by everolimus nor dual mTOR/PI(3)K inhibition by NVP-BEZ235 was able to enhance TRAIL susceptibility in any of the tested cell lines. In contrast, dual PI(3)K-Akt-mTOR and Raf-MEK-Erk pathway inhibition by the IGF-1R inhibitor NVP-AEW541 effectively restored TRAIL sensitivity in NCI-H727 bronchus carcinoid cells. Furthermore, blocking Raf-MEK-Erk signalling by the novel Raf inhibitor Raf265 significantly enhanced TRAIL sensitivity in NCI-H727 and CM insulinoma cells. While having no effect on FLIP S or caspase-8 expression, Raf265 strongly decreased Bcl-2 levels in those cell lines susceptible to its TRAIL-sensitizing action. Taken together, our findings suggest that combinations of Raf-MEK-Erk pathway inhibitors and TRAIL might offer a novel therapeutic strategy in NET disease.

Diabetologia, 2000

The Ca 2+ /calmodulin-dependent protein kinase II (CaMK II) is a multifunctional enzyme which is ... more The Ca 2+ /calmodulin-dependent protein kinase II (CaMK II) is a multifunctional enzyme which is widely expressed from yeast to mammals and occurs in four different isoforms termed a, b, g and d which are derived from different genes [1, 2]. The highest concentrations are in the CNS where the aisoform and b-isoform are involved in neurotransmitter release [1, 2] whereas the g-isoform and disoform occur in most peripheral cells [3, 4] and participate in control of cell cycle, metabolism, gene expression and membrane excitability. Insulin secretion in response to glucose and other nutrient stimuli is dependent on Ca 2+ and CaMK II seems to play an important part in this process [5±7]. Impairment of insulin secretion in response to glucose is an early event in the development of adult Type II (non-insulin-dependent) diabetes mellitus making it Diabetologia (2000) 43: 465±473

Diabetes, 2012

Diabetes is generally diagnosed too late. Therefore, biomarkers indicating early stages of β-cell... more Diabetes is generally diagnosed too late. Therefore, biomarkers indicating early stages of β-cell dysfunction and mass reduction would facilitate timely counteraction. Transgenic pigs expressing a dominant-negative glucose-dependent insulinotropic polypeptide receptor (GIPRdn) reveal progressive deterioration of glucose control and reduction of β-cell mass, providing a unique opportunity to study metabolic changes during the prediabetic period. Plasma samples from intravenous glucose tolerance tests of 2.5- and 5-month-old GIPRdn transgenic and control animals were analyzed for 163 metabolites by targeted mass spectrometry. Analysis of variance revealed that 26 of 163 parameters were influenced by the interaction Genotype × Age (P ≤ 0.0001) and thus are potential markers for progression within the prediabetic state. Among them, the concentrations of seven amino acids (Phe, Orn, Val, xLeu, His, Arg, and Tyr) were increased in 2.5-month-old but decreased in 5-month-old GIPRdn transgen...

Islets

The members of the Suppressor of Cytokine Signaling (SOCS) protein family mainly modulate the Jan... more The members of the Suppressor of Cytokine Signaling (SOCS) protein family mainly modulate the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway. SOCS-1 and SOCS-3 have already been shown to influence growth and apoptosis of pancreatic beta cells. We hypothesized that SOCS-2, which is expressed in pancreatic islets, also contributes to β-cell physiology. We tested this hypothesis in vivo in SOCS-2-/- knockout mice and in vitro in Ins-1E rat insulinoma cells. We found that SOCS-2-/- mice have normal islet insulin secretion and unchanged glucose and insulin tolerance compared to wildtype controls. SOCS-2-/- are bigger than wildtype mice but body weight-corrected β-cell mass and islet morphology were normal. Growth hormone-induced proliferation of Ins-1E cells was not affected by either siRNA-mediated SOCS-2 knockdown or stable SOCS-2 overexpression. Interleukin-1β mediated cell death in vitro was unchanged after SOCS-2 knockdown. Similarly, autoimmune d...

Journal of Translational Medicine, Feb 25, 2015

Oncotarget, Jan 28, 2016

DNA repair defects due to detrimental BRCA2-mutations confer increased susceptibility towards DNA... more DNA repair defects due to detrimental BRCA2-mutations confer increased susceptibility towards DNA interstrand-crosslinking (ICL) agents and define patient subpopulations for individualized genotype-based cancer therapy. However, due to the side effects of these drugs, there is a need to identify additional agents, which could be used alone or in combination with ICL-agents. Therefore, we investigated whether BRCA2-mutations might also increase the sensitivity towards TRAIL-receptors (TRAIL-R)-targeting compounds. Two independent model systems were applied: a BRCA2 gene knockout and a BRCA2 gene complementation model. The effects of TRAIL-R-targeting compounds and ICL-agents on cell viability, apoptosis and cell cycle distribution were compared in BRCA2-proficient versus-deficient cancer cells in vitro. In addition, the effects of the TRAIL-R2-targeting antibody LBY135 were assessed in vivo using a murine tumor xenograft model. BRCA2-deficient cancer cells displayed an increased sens...

PloS one, 2015

The mTORC1-inhibitor everolimus shows limited efficacy in treating patients with gastro-entero-pa... more The mTORC1-inhibitor everolimus shows limited efficacy in treating patients with gastro-entero-pancreatic or pulmonary neuroendocrine tumors (NETs), and poor outcome in patients with malignant pheochromocytoma or hepatic carcinoma. We speculated that any effect may be enhanced by antogonising other signaling pathways. Therefore, we tested the effect of lovastatin-known to inhibit both ERK and AKT signaling-and everolimus, separately and in combination, on cell viability and signaling pathways in human midgut (GOT), pancreatic (BON1), and pulmonary (H727) NET, hepatocellular carcinoma (HepG2, Huh7), and mouse pheochromocytoma (MPC, MTT) cell lines. Lovastatin and everolimus separately significantly reduced cell viability in H727, HepG2, Huh7, MPC and MTT cells at clinically relevant doses (P ≤ 0.05). However, high doses of lovastatin were necessary to affect GOT or BON1 cell viability. Clinically relevant doses of both drugs showed additive anti-tumor effects in H727, HepG2, Huh7, MP...

American journal of physiology. Endocrinology and metabolism, 2002

Impaired glucose tolerance (IGT) and non-insulin-dependent diabetes mellitus (NIDDM) are associat... more Impaired glucose tolerance (IGT) and non-insulin-dependent diabetes mellitus (NIDDM) are associated with an impaired ability of the beta-cell to sense and respond to small changes in plasma glucose. The aim of this study was to establish whether acute hyperglycemia per se plays a role in inducing this defect in beta-cell response. Seven healthy volunteers with no family history of NIDDM were studied on two occasions during a 12-h oscillatory glucose infusion with a periodicity of 144 min. Once, low-dose glucose was infused at a mean rate of 6 mg x kg(-1) x min(-1) and amplitude 33% above and below the mean rate, and, once, high-dose glucose was infused at 12 mg x kg(-1) x min(-1) and amplitude 16% above and below the mean rate. Mean glucose levels were significantly higher during the high-dose compared with the low-dose glucose infusion [9.5 +/- 0.8 vs. 6.8 +/- 0.2 mM (P < 0.01)], resulting in increased mean insulin secretion rates [ISRs; 469.1 +/- 43.8 vs. 268.4 +/- 29 pmol/min ...

Molecular Endocrinology, 2001

Activation of the G-protein-coupled receptor for glucose-dependent insulinotropic polypeptide fac... more Activation of the G-protein-coupled receptor for glucose-dependent insulinotropic polypeptide facilitates insulin-release from pancreatic ␤-cells. In the present study, we examined whether glucosedependent insulinotropic polypeptide also acts as a growth factor for the ␤-cell line INS-1. Here, we show that glucose-dependent insulinotropic polypeptide induced cellular proliferation synergistically with glucose between 2.5 mM and 15 mM by pleiotropic activation of signaling pathways. Glucose-dependent insulinotropic polypeptide stimulated the signaling modules of PKA/cAMP regulatory element binder, MAPK, and PI3K/protein kinase B in a glucose-and dose-dependent manner. Janus kinase 2 and signal transducer and activators of transcription 5/6 pathways were not stimulated by glucose-dependent insulinotropic polypeptide. Activation of PI3K by glucose-dependent insulinotropic polypeptide and glucose was associated with insulin receptor substrate isoforms insulin receptor substrate-2 and growth factor bound-2 associated binder-1 and PI3K isoforms p85␣, p110␣, p110␤, and p110␥. Downstream of PI3K, glucose-dependent insulinotropic polypeptide-stimulated protein kinase B␣ and protein kinase B␤ isoforms and phosphorylated glycogen synthase kinase-3, forkhead transcription factor FKHR, and p70 S6K. These data indicate that glucose-dependent insulinotropic polypeptide functions synergistically with glucose as a pleiotropic growth factor for insulin-producing ␤-cells, which may play a role for metabolic adaptations of insulin-producing cells during type II diabetes.

Journal of Nuclear Medicine, 2012

The Journal of Clinical Endocrinology & Metabolism, 2010

International Journal of Clinical Practice, 2010

Saxagliptin is non-inferior to glipizide in patients with type 2 diabetes mellitus inadequately c... more Saxagliptin is non-inferior to glipizide in patients with type 2 diabetes mellitus inadequately controlled on metformin alone: a 52-week randomised controlled trial <> Saxagliptin non-inferior to glipizide as add-on therapy to metformin <>

FEBS Letters, 1990

Amylin, a 37 amino acid C‐terminal amidated peptide is an integral part of secretory granules of ... more Amylin, a 37 amino acid C‐terminal amidated peptide is an integral part of secretory granules of pancreatic β‐cells. Utilizing a specific radioimmunoassay system we demonstrate in the present study a cosecretion of amylin and insulin from the isolated rat pancreas. The secretion pattern of both peptides during glucose or glucose plus arginine stimulation is identical. The molar ratio of amylin amounts to 10% of that of insulin. The biological significance of amylin is still unknown, but a paracrine/endocrine role in glucose homeostasis is speculated.

FEBS Letters, 1992

Glucagon‐like peptide‐1 (7–36)amide (GLP‐1 (7–36)amide) represents a physiologically important in... more Glucagon‐like peptide‐1 (7–36)amide (GLP‐1 (7–36)amide) represents a physiologically important incretin in mammals including man. Receptors for GLP‐1 (7–36)amide have been described in RINm5F cells. We have solubilized active GLP‐1 (7–36)amide receptors from RINm5F cell membranes utilizing the detergents octyl‐β‐glucoside and CHAPS; Triton X‐100 and Lubrol PX were ineffective. Binding of radiolabeled GLP‐1(7–36)amide to the solubilized receptor was inhibited conentration‐dependently by addition of unlabeled peptide. Scatchard analysis of binding data revealed a single class of binding sites with K a= 0.26 ± 0.03 nM and B max= 65.4 ± 21.24 fmol/mg of protein for the membrane‐bound receptor and K a= 22.54 ± 4.42 μM and B max= 3.9 ± 0.79 pmol/mg of protein for the solubilized receptor. The binding of the radiolabel to the solubilized receptor was dependent both on the concentrations of mono‐ and divalent cations and the protein/detergent ratio in the incubation buffer. The membrane bou...

FEBS Letters, 1992

This study was designed to search for the expression of the small-moleeular.wei ,l~ht GTP-binding... more This study was designed to search for the expression of the small-moleeular.wei ,l~ht GTP-binding protein rab3a in endocrine pancreatic cell lines. Total RNA was isolated from fi~e different cell lines (RINmSF, RIN 104836, fl-TCI, HIT-15. and INRI-G9) and from whole rat brain. The expression of rab3a was analyzed by Northern blots. Similar as in brain two transcripts of 1300 and 1800 bp were detected in RIN.e~IIs at low stringency conditions with the predominant signal at 1300 bp. At high stringency the stronger signal was at 1800 bp. When a 300 bp Pstl fmlgnent derived from the coding region ofrab3a was utilized as probe the 1800 bp signal was predominant under each condition. Only a faint band at 1800 bp occurred in preparations from ffrCl.cells and no signal at all was found in HIT-I 5 and INRI-Gg-celIs. In conclusion, rab3a is expressed in rat insulln-releashag insulinoma.derived RIN.eells with a specific 1800 bp transcription product.

FEBS Letters, 1991

125I‐labelled GLP‐I(7–36)amide was cross‐linked to a specific binding protein in rat lung membran... more 125I‐labelled GLP‐I(7–36)amide was cross‐linked to a specific binding protein in rat lung membranes using disuccinimidyl suberate. A single radio‐labelled band at M r 66000 was identified by SDS‐PAGE after solubilization of the ligand‐binding protein complex which is consistent with the presence of a single class of binding sites on rat lung membranes. The band was undetectable when 1 μmol/1 GLP‐I(7–36)amide was included in the binding assay. No change in the mobility of the band was observed under reducing conditions suggesting that the binding protein in the receptor is not part of a larger disulphide‐liked protein. The intensity of the radiolabelled protein band was reduced when the incubation with 125I‐labelled GLP‐I(7–36)amide was carried out in the presence of guanine nucleotides suggesting that the GLP‐I(7–36)amide receptor is coupled to the adenylate cyclase system.

Endocrine Related Cancer, 2011

The tumour-selective death receptor ligand tumour necrosis factor-related apoptosis-inducing liga... more The tumour-selective death receptor ligand tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising agent for the treatment of human cancer. However, many tumours have evolved mechanisms to resist TRAIL-induced apoptosis. A number of studies have demonstrated that aberrant PI(3)K-Akt-mTOR survival signalling may confer TRAIL resistance by altering the balance between pro-and anti-apoptotic proteins. Here, we show that neuroendocrine tumour (NET) cell lines of heterogeneous origin exhibit a range of TRAIL sensitivities and that TRAIL sensitivity correlates with the expression of FLIP S , caspase-8, and Bcl-2. Neither single mTOR inhibition by everolimus nor dual mTOR/PI(3)K inhibition by NVP-BEZ235 was able to enhance TRAIL susceptibility in any of the tested cell lines. In contrast, dual PI(3)K-Akt-mTOR and Raf-MEK-Erk pathway inhibition by the IGF-1R inhibitor NVP-AEW541 effectively restored TRAIL sensitivity in NCI-H727 bronchus carcinoid cells. Furthermore, blocking Raf-MEK-Erk signalling by the novel Raf inhibitor Raf265 significantly enhanced TRAIL sensitivity in NCI-H727 and CM insulinoma cells. While having no effect on FLIP S or caspase-8 expression, Raf265 strongly decreased Bcl-2 levels in those cell lines susceptible to its TRAIL-sensitizing action. Taken together, our findings suggest that combinations of Raf-MEK-Erk pathway inhibitors and TRAIL might offer a novel therapeutic strategy in NET disease.

Diabetologia, 2000

The Ca 2+ /calmodulin-dependent protein kinase II (CaMK II) is a multifunctional enzyme which is ... more The Ca 2+ /calmodulin-dependent protein kinase II (CaMK II) is a multifunctional enzyme which is widely expressed from yeast to mammals and occurs in four different isoforms termed a, b, g and d which are derived from different genes [1, 2]. The highest concentrations are in the CNS where the aisoform and b-isoform are involved in neurotransmitter release [1, 2] whereas the g-isoform and disoform occur in most peripheral cells [3, 4] and participate in control of cell cycle, metabolism, gene expression and membrane excitability. Insulin secretion in response to glucose and other nutrient stimuli is dependent on Ca 2+ and CaMK II seems to play an important part in this process [5±7]. Impairment of insulin secretion in response to glucose is an early event in the development of adult Type II (non-insulin-dependent) diabetes mellitus making it Diabetologia (2000) 43: 465±473

Diabetes, 2012

Diabetes is generally diagnosed too late. Therefore, biomarkers indicating early stages of β-cell... more Diabetes is generally diagnosed too late. Therefore, biomarkers indicating early stages of β-cell dysfunction and mass reduction would facilitate timely counteraction. Transgenic pigs expressing a dominant-negative glucose-dependent insulinotropic polypeptide receptor (GIPRdn) reveal progressive deterioration of glucose control and reduction of β-cell mass, providing a unique opportunity to study metabolic changes during the prediabetic period. Plasma samples from intravenous glucose tolerance tests of 2.5- and 5-month-old GIPRdn transgenic and control animals were analyzed for 163 metabolites by targeted mass spectrometry. Analysis of variance revealed that 26 of 163 parameters were influenced by the interaction Genotype × Age (P ≤ 0.0001) and thus are potential markers for progression within the prediabetic state. Among them, the concentrations of seven amino acids (Phe, Orn, Val, xLeu, His, Arg, and Tyr) were increased in 2.5-month-old but decreased in 5-month-old GIPRdn transgen...