CPT1A and fatty acid β-oxidation are essential for tumor cell growth and survival in hormone receptor-positive breast cancer

Chromosome 11q13-14 amplification is a defining feature of high-risk hormone receptor-positive (HR+) breast cancer; however, the mechanism(s) by which this amplicon contributes to breast tumorigenesis remains unclear. In the current study, proteogenomic analyses of >3000 breast tumors from the TCGA, METABRIC and CPTAC studies demonstrated that carnitine palmitoyltransferase 1A (CPT1A), which is localized to this amplicon, is overexpressed at the mRNA and protein level in aggressive luminal tumors, strongly associated with indicators of tumor proliferation and a predictor of poor prognosis. In vitro genetic studies demonstrated that CPT1A is required for and can promote luminal breast cancer proliferation, survival, as well as colony and mammosphere formation. Since CPT1A is the rate-limiting enzyme during fatty acid oxidation (FAO), our data indicate that FAO may be essential for these tumors. Pharmacologic inhibition of FAO prevented in vitro and in vivo tumor growth and cell proliferation as well as promoted apoptosis in luminal breast cancer cells and orthotopic xenograft tumor models. Collectively, our data establish an oncogenic role for CPT1A and FAO in HR+ luminal tumors and provide preclinical evidence and rationale supporting further investigation of FAO as a potential therapeutic opportunity for the treatment of HR+ breast cancer.

Abstract P3-03-02: Integrative proteogenomic analyses identifies CPT1A and fatty acid oxidation as a potential therapeutic strategy in hormone receptor positive breast cancer

Background: Clinically, approximately two-thirds of the nearly 250,000 breast cancer cases diagnosed each year in the United States are hormone receptor positive (HR+), luminal breast tumors. Slower growing luminal breast tumors are often successfully treated using endocrine based therapies resulting in a relatively good prognosis for these patients. However more highly proliferative luminal tumors are often resistant, or become resistant, to current therapies leading to a worse outcome for these patients. As such, there is a critical need to identify genomic alterations and dysregulated signaling pathway in this subset of tumors that may represent novel therapeutic opportunities. Methods: In order to identify genetic events responsible for tumorigenesis and to identify potential drug-able genetic alterations and/or pathways associated with high levels of proliferation in HR+ tumors, we used an integrative genomics-based strategy to interrogate orthogonal genome-wide data from more than 2,500 patients from the TCGA, METABRIC, CPTAC studies. Data from a genome-wide RNAi screen was used to delineate essential from non-essential genes in HR+ breast cancer cell lines. Genetic and pharmacological-based in vitro and in vivo studies were used to demonstrate the impact identified candidate genes on cell viability, proliferation, colony formation, spheroid formation and tumor growth rate. Results: Integrative genomic analyses of human breast tumors identified DNA amplification as well as mRNA and protein over-expression of carnitine palmitoyltransferase 1A (CPT1A) in highly proliferative luminal tumors. Further in silico analyses demonstrated that high CPT1A expression corresponded with protein markers of proliferation in human tumors and is prognostic in HR+ tumors in both the TCGA and METABRIC cohorts. Since CPT1A is the rate limiting enzyme responsible for fatty acid import into the mitochondria during Fatty Acid β Oxidation (FAO), these data indicate that highly proliferative luminal tumors may utilize FAO as a prominent energy source. As such, we hypothesized that inhibiting CPT1A and/or FAO in this subset of tumors or cell lines may represent a potential therapeutic opportunity. Consistent with our hypothesis, analyses of data from a genome-wide RNAi screen in 27 breast cancer cell lines suggested that HR+ cells lines are dependent on CPT1A expression. Importantly, we experimentally demonstrated that in vitro genetic silencing of CPT1A or pharmacological inhibition of FAO in ER+ breast cancer cell lines results in reduced cell viability and increased cell death as well as decreased spheroid formation. Importantly, our data indicated that in vivo inhibition of CPT1A resulted in decreased tumor volume and growth rate in orthotopic xenograft tumor models. Conclusions: In this study, integrative proteogenomic analyses identified amplification and over-expression of CPT1A in highly proliferative ER+ breast tumors. In vitro and in vivo studies demonstrated that CPT1A is an essential oncogenic driver in HR+/luminal breast cancer and establish CTP1A/FAO inhibition as a putative therapeutic strategy for treatment of these tumors.

Citation Format: Michael L Gatza, Vrushank Bhatt, Kimberly Parker, Guarav Mehta, Christen Khella, Yanxiang Guo, Nidhi Jariwala. Integrative proteogenomic analyses identifies CPT1A and fatty acid oxidation as a potential therapeutic strategy in hormone receptor positive breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-03-02.

Posttranscriptional Inhibition of Protein Tyrosine Phosphatase Nonreceptor Type 23 by Staphylococcal Nuclease and Tudor Domain Containing 1: Implications for Hepatocellular Carcinoma

Oncoprotein staphylococcal nuclease and tudor domain containing 1 (SND1) regulates gene expression at a posttranscriptional level in multiple cancers, including hepatocellular carcinoma (HCC). Staphylococcal nuclease (SN) domains of SND1 function as a ribonuclease (RNase), and the tudor domain facilitates protein–oligonucleotide interaction. In the present study, we aimed to identify RNA interactome of SND1 to obtain enhanced insights into gene regulation by SND1. RNA interactome was identified by immunoprecipitation (IP) of RNA using anti‐SND1 antibody from human HCC cells followed by RNA immunoprecipitation sequencing (RIP‐Seq). Among RNA species that showed more than 10‐fold enrichment over the control, we focused on the tumor suppressor protein tyrosine phosphatase nonreceptor type 23 (PTPN23) because its regulation by SND1 and its role in HCC are not known. PTPN23 levels were down‐regulated in human HCC cells versus normal hepatocytes and in human HCC tissues versus normal adjacent liver, as revealed by immunohistochemistry. In human HCC cells, knocking down SND1 increased and overexpression of SND1 decreased PTPN23 protein. RNA binding and degradation assays revealed that SND1 binds to and degrades the 3′‐untranslated region (UTR) of PTPN23 messenger RNA (mRNA). Tetracycline‐inducible PTPN23 overexpression in human HCC cells resulted in significant inhibition in proliferation, migration, and invasion and in vivo tumorigenesis. PTPN23 induction caused inhibition in activation of tyrosine‐protein kinase Met (c‐Met), epidermal growth factor receptor (EGFR), Src, and focal adhesion kinase (FAK), suggesting that, as a putative phosphatase, PTPN23 inhibits activation of these oncogenic kinases. Conclusion: PTPN23 is a novel target of SND1, and our findings identify PTPN23 as a unique tumor suppressor for HCC. PTPN23 might function as a homeostatic regulator of multiple kinases, restraining their activation.

Astrocyte Elevated Gene-1 Regulates Macrophage Activation in Hepatocellular Carcinogenesis

Chronic inflammation is a known hallmark of cancer and is central to the onset and progression of hepatocellular carcinoma (HCC). Hepatic macrophages play a critical role in the inflammatory process leading to HCC. The oncogene Astrocyte elevated gene-1 (AEG-1) regulates NFκB activation, and germline knockout of AEG-1 in mice (AEG-1-/-) results in resistance to inflammation and experimental HCC. In this study, we developed conditional hepatocyte- and myeloid cell-specific AEG-1-/- mice (AEG-1ΔHEP and AEG-1ΔMAC, respectively) and induced HCC by treatment with N-nitrosodiethylamine (DEN) and phenobarbital (PB). AEG-1ΔHEP mice exhibited a significant reduction in disease severity compared with control littermates, while AEG-1ΔMAC mice were profoundly resistant. In vitro, AEG-1-/- hepatocytes exhibited increased sensitivity to stress and senescence. Notably, AEG-1-/- macrophages were resistant to either M1 or M2 differentiation with significant inhibition in migration, endothelial adhesion, and efferocytosis activity, indicating that AEG-1 ablation renders macrophages functionally anergic. These results unravel a central role of AEG-1 in regulating macrophage activation and indicate that AEG-1 is required in both tumor cells and tumor microenvironment to stimulate hepatocarcinogenesis.Significance: These findings distinguish a novel role of macrophage-derived oncogene AEG-1 from hepatocellular AEG-1 in promoting inflammation and driving tumorigenesis. Cancer Res; 78(22); 6436-46. ©2018 AACR.

SMAD4 Suppresses WNT-Driven Dedifferentiation and Oncogenesis in the Differentiated Gut Epithelium

The cell of origin of colon cancer is typically thought to be the resident somatic stem cells, which are immortal and escape the continual cellular turnover characteristic of the intestinal epithelium. However, recent studies have identified certain conditions in which differentiated cells can acquire stem-like properties and give rise to tumors. Defining the origins of tumors will inform cancer prevention efforts as well as cancer therapies, as cancers with distinct origins often respond differently to treatments. We report here a new condition in which tumors arise from the differentiated intestinal epithelium. Inactivation of the differentiation-promoting transcription factor SMAD4 in the intestinal epithelium was surprisingly well tolerated in the short term. However, after several months, adenomas developed with characteristics of activated WNT signaling. Simultaneous loss of SMAD4 and activation of the WNT pathway led to dedifferentiation and rapid adenoma formation in differentiated tissue. Transcriptional profiling revealed acquisition of stem cell characteristics, and colabeling indicated that cells expressing differentiated enterocyte markers entered the cell cycle and reexpressed stem cell genes upon simultaneous loss of SMAD4 and activation of the WNT pathway. These results indicate that SMAD4 functions to maintain differentiated enterocytes in the presence of oncogenic WNT signaling, thus preventing dedifferentiation and tumor formation in the differentiated intestinal epithelium.Significance: This work identifies a mechanism through which differentiated cells prevent tumor formation by suppressing oncogenic plasticity. Cancer Res; 78(17); 4878-90. ©2018 AACR.

A novel role of astrocyte elevated gene-1 (AEG-1) in regulating nonalcoholic steatohepatitis (NASH)

Nonalcoholic steatohepatitis (NASH) is the most prevalent cause of chronic liver disease in the Western world. However, an optimum therapy for NASH is yet to be established, mandating more in-depth investigation into the molecular pathogenesis of NASH to identify novel regulatory molecules and develop targeted therapies. Here, we unravel a unique function of astrocyte elevated gene-1(AEG-1)/metadherin in NASH using a transgenic mouse with hepatocyte-specific overexpression of AEG-1 (Alb/AEG-1) and a conditional hepatocyte-specific AEG-1 knockout mouse (AEG-1^ΔHEP ). Alb/AEG-1 mice developed spontaneous NASH whereas AEG-1^ΔHEP mice were protected from high-fat diet (HFD)-induced NASH. Intriguingly, AEG-1 overexpression was observed in livers of NASH patients and wild-type (WT) mice that developed steatosis upon feeding HFD. In-depth molecular analysis unraveled that inhibition of peroxisome proliferator-activated receptor alpha activity resulting in decreased fatty acid β-oxidation, augmentation of translation of fatty acid synthase resulting in de novo lipogenesis, and increased nuclear factor kappa B-mediated inflammation act in concert to mediate AEG-1-induced NASH. Therapeutically, hepatocyte-specific nanoparticle-delivered AEG-1 small interfering RNA provided marked protection from HFD-induced NASH in WT mice.

CONCLUSION

AEG-1 might be a key molecule regulating initiation and progression of NASH. AEG-1 inhibitory strategies might be developed as a potential therapeutic intervention in NASH patients. (Hepatology 2017;66:466-480).

IGFBP7 Deletion Promotes Hepatocellular Carcinoma

Activation of IGF signaling is a major oncogenic event in diverse cancers, including hepatocellular carcinoma (HCC). In this setting, the insulin-like growth factor binding protein IGFBP7 inhibits IGF signaling by binding the IGF1 receptor (IGF1R), functioning as a candidate tumor suppressor. IGFBP7 abrogates tumors by inhibiting angiogenesis and inducing cancer-specific senescence and apoptosis. Here, we report that Igfbp7-deficient mice exhibit constitutively active IGF signaling, presenting with proinflammatory and immunosuppressive microenvironments and spontaneous liver and lung tumors occurring with increased incidence in carcinogen-treated subjects. Igfbp7 deletion increased proliferation and decreased senescence of hepatocytes and mouse embryonic fibroblasts, effects that were blocked by treatment with IGF1 receptor inhibitor. Significant inhibition of genes regulating immune surveillance was observed in Igfbp7^-/- murine livers, which was associated with a marked inhibition in antigen cross-presentation by Igfbp7^-/- dendritic cells. Conversely, IGFBP7 overexpression inhibited growth of HCC cells in syngeneic immunocompetent mice. Depletion of CD4⁺ or CD8⁺ T lymphocytes abolished this growth inhibition, identifying it as an immune-mediated response. Our findings define an immune component of the pleiotropic mechanisms through which IGFBP7 suppresses HCC. Furthermore, they offer a genetically based preclinical proof of concept for IGFBP7 as a therapeutic target for immune management of HCC. Cancer Res; 77(15); 4014-25. ©2017 AACR.

Oncogenic Role of SND1 in Development and Progression of Hepatocellular Carcinoma

SND1, a subunit of the miRNA regulatory complex RISC, has been implicated as an oncogene in hepatocellular carcinoma (HCC). In this study, we show that hepatocyte-specific SND1 transgenic mice (Alb/SND1 mice) develop spontaneous HCC with partial penetrance and exhibit more highly aggressive HCC induced by chemical carcinogenesis. Livers from Alb/SND1 mice exhibited a relative increase in inflammatory markers and spheroid-generating tumor-initiating cells (TIC). Mechanistic investigations defined roles for Akt and NF-κB signaling pathways in promoting TIC formation in Alb/SND1 mice. In human xenograft models of subcutaneous or orthotopic HCC, administration of the selective SND1 inhibitor 3', 5'-deoxythymidine bisphosphate (pdTp), inhibited tumor formation without effects on body weight or liver function. Our work establishes an oncogenic role for SND1 in promoting TIC formation and highlights pdTp as a highly selective SND1 inhibitor as a candidate therapeutic lead to treat advanced HCC. Cancer Res; 77(12); 3306-16. ©2017 AACR.

Emerging role of lncRNA in cancer: a potential avenue in molecular medicine

Hepatocellular carcinoma (HCC) accounts for the second largest number of cancer related deaths globally with limited management options for the advanced disease. Although substantial research has identified molecular targets, with strong validation in pre-clinical in vivo studies, translation of therapeutics to clinics has shown modest success. In a recent manuscript in Hepatology, Zhou and Yang et al. unravel a novel p53 associated long non-coding RNA (PRAL) as a potential prognostic marker and molecular target in HCC. Their work provides a promising approach at capitalizing the tumor suppressive role of p53 protein in fighting HCC. More importantly, it emphasizes the evolving significance of long non-coding RNAs (lncRNA) in molecular medicine. Current research trends focus on identifying and understanding roles of lncRNA in regulation of gene expression relevant to multiple disease pathophysiologies thereby presenting a new avenue of research in molecular and translational medicine.

Small molecule inhibitors of Late SV40 Factor (LSF) abrogate hepatocellular carcinoma (HCC): Evaluation using an endogenous HCC model

Hepatocellular carcinoma (HCC) is a lethal malignancy with high mortality and poor prognosis. Oncogenic transcription factor Late SV40 Factor (LSF) plays an important role in promoting HCC. A small molecule inhibitor of LSF, Factor Quinolinone Inhibitor 1 (FQI1), significantly inhibited human HCC xenografts in nude mice without harming normal cells. Here we evaluated the efficacy of FQI1 and another inhibitor, FQI2, in inhibiting endogenous hepatocarcinogenesis. HCC was induced in a transgenic mouse with hepatocyte-specific overexpression of c-myc (Alb/c-myc) by injecting N-nitrosodiethylamine (DEN) followed by FQI1 or FQI2 treatment after tumor development. LSF inhibitors markedly decreased tumor burden in Alb/c-myc mice with a corresponding decrease in proliferation and angiogenesis. Interestingly, in vitro treatment of human HCC cells with LSF inhibitors resulted in mitotic arrest with an accompanying increase in CyclinB1. Inhibition of CyclinB1 induction by Cycloheximide or CDK1 activity by Roscovitine significantly prevented FQI-induced mitotic arrest. A significant induction of apoptosis was also observed upon treatment with FQI. These effects of LSF inhibition, mitotic arrest and induction of apoptosis by FQI1s provide multiple avenues by which these inhibitors eliminate HCC cells. LSF inhibitors might be highly potent and effective therapeutics for HCC either alone or in combination with currently existing therapies.

Abstract 3823: Staphylococcal nuclease and tudor domain containing 1 (SND1) in development and progression of hepatocellular carcinoma

Staphylococcal nuclease and tudor domain containing 1 (SND1) is identified as an oncogene in hepatocellular carcinoma (HCC) and overexpression of SND1 has been correlated with HCC progression. Here, we present effect of liver specific overexpression of human SND1 in a novel transgenic mouse model. We observe greater tumor load and tumor volume in transgenic mice than wildtype mice, when subjected to chemical carcinogenesis. Approximately 30% of transgenic animals manifest spontaneous tumorigenesis with age. Liver specific expression of cancer stem cell markers such as EpCAM and CD133 as well as inflammatory markers was found to be higher in transgenic mice. SND1 overexpressing hepatocytes show increased activation of insulin and NFκB signaling pathways compared to wildtype hepatocytes. However, no significant differences in liver weight or liver function was noted among transgenic and wildtype animals. Overall, our findings confirm that overexpression of SND1 in vivo plays a vital role in development and progression of HCC. Thus, molecular targeting of SND1 seems to be potential therapeutic intervention for HCC management in patients.

Citation Format: Nidhi Jariwala, Devaraja Rajasekaran, Rachel Gredler, Maaged Akiel, Chadia Robertson, Paul Fisher, Arun Sanyal, Devanand Sarkar. Staphylococcal nuclease and tudor domain containing 1 (SND1) in development and progression of hepatocellular carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3823.

Staphylococcal Nuclease and Tudor Domain Containing 1 (SND1 Protein) Promotes Hepatocarcinogenesis by Inhibiting Monoglyceride Lipase (MGLL)

Staphylococcal nuclease and tudor domain containing 1 (SND1) is overexpressed in multiple cancers, including hepatocellular carcinoma (HCC), and functions as an oncogene. This study was carried out to identify novel SND1-interacting proteins to better understand its molecular mechanism of action. SND1-interacting proteins were identified by a modified yeast two-hybrid assay. Protein-protein interaction was confirmed by co-immunoprecipitation analysis. Monoglyceride lipase (MGLL) expression was analyzed by quantitative RT-PCR, Western blot, and immunohistochemistry. MGLL-overexpressing clones were analyzed for cell proliferation and cell cycle analysis and in vivo tumorigenesis in nude mice. MGLL was identified as an SND1-interacting protein. Interaction of SND1 with MGLL resulted in ubiquitination and proteosomal degradation of MGLL. MGLL expression was detected in normal human hepatocytes and mouse liver, although it was undetected in human HCC cell lines. An inverse correlation between SND1 and MGLL levels was identified in a human HCC tissue microarray as well as in the TCGA database. Forced overexpression of MGLL in human HCC cells resulted in marked inhibition in cell proliferation with a significant delay in cell cycle progression and a marked decrease in tumor growth in nude mouse xenograft assays. MGLL overexpression inhibited Akt activation that is independent of enzymatic activity of MGLL and overexpression of a constitutively active Akt rescued cells from inhibition of proliferation and restored normal cell cycle progression. This study unravels a novel mechanism of SND1 function and identifies MGLL as a unique tumor suppressor for HCC. MGLL might function as a homeostatic regulator of Akt restraining its activation.

The role of AEG-1 in the development of liver cancer

AEG-1 is an oncogene that is overexpressed in all cancers, including hepatocellular carcinoma. AEG-1 plays a seminal role in promoting cancer development and progression by augmenting proliferation, invasion, metastasis, angiogenesis and chemoresistance, all hallmarks of aggressive cancer. AEG-1 mediates its oncogenic function predominantly by interacting with various protein complexes. AEG-1 acts as a scaffold protein, activating multiple protumorigenic signal transduction pathways, such as MEK/ERK, PI3K/Akt, NF-κB and Wnt/β-catenin while regulating gene expression at transcriptional, post-transcriptional and translational levels. Our recent studies document that AEG-1 is fundamentally required for activation of inflammation. A comprehensive and convincing body of data currently points to AEG-1 as an essential component critical to the onset and progression of cancer. The present review describes the current knowledge gleaned from patient and experimental studies as well as transgenic and knockout mouse models, on the impact of AEG-1 on hepatocarcinogenesis.

Combination of Nanoparticle-Delivered siRNA for Astrocyte Elevated Gene-1 (AEG-1) and All-trans Retinoic Acid (ATRA): An Effective Therapeutic Strategy for Hepatocellular Carcinoma (HCC)

Hepatocellular carcinoma (HCC) is a fatal cancer with no effective therapy. Astrocyte elevated gene-1 (AEG-1) plays a pivotal role in hepatocarcinogenesis and inhibits retinoic acid-induced gene expression and cell death. The combination of a lentivirus expressing AEG-1 shRNA and all-trans retinoic acid (ATRA) profoundly and synergistically inhibited subcutaneous human HCC xenografts in nude mice. We have now developed liver-targeted nanoplexes by conjugating poly(amidoamine) (PAMAM) dendrimers with polyethylene glycol (PEG) and lactobionic acid (Gal) (PAMAM-PEG-Gal) which were complexed with AEG-1 siRNA (PAMAM-AEG-1si). The polymer conjugate was characterized by (1)H-NMR, MALDI, and mass spectrometry; and optimal nanoplex formulations were characterized for surface charge, size, and morphology. Orthotopic xenografts of human HCC cell QGY-7703 expressing luciferase (QGY-luc) were established in the livers of athymic nude mice and tumor development was monitored by bioluminescence imaging (BLI). Tumor-bearing mice were treated with PAMAM-siCon, PAMAM-siCon+ATRA, PAMAM-AEG-1si, and PAMAM-AEG-1si+ATRA. In the control group the tumor developed aggressively. ATRA showed little effect due to high AEG-1 levels in QGY-luc cells. PAMAM-AEG-1si showed significant reduction in tumor growth, and the combination of PAMAM-AEG-1si+ATRA showed profound and synergistic inhibition so that the tumors were almost undetectable by BLI. A marked decrease in AEG-1 level was observed in tumor samples treated with PAMAM-AEG-1si. The group treated with PAMAM-AEG-1si+ATRA nanoplexes showed increased necrosis, inhibition of proliferation, and increased apoptosis when compared to other groups. Liver is an ideal organ for RNAi therapy and ATRA is an approved anticancer agent. Our exciting observations suggest that the combinatorial approach might be an effective way to combat HCC.

Role of the staphylococcal nuclease and tudor domain containing 1 in oncogenesis (review)

The staphylococcal nuclease and tudor domain containing 1 (SND1) is a multifunctional protein overexpressed in breast, prostate, colorectal and hepatocellular carcinomas and malignant glioma. Molecular studies have revealed the multifaceted activities of SND1 involved in regulating gene expression at transcriptional as well as post-transcriptional levels. Early studies identified SND1 as a transcriptional co-activator. SND1 is also a component of RNA-induced silencing complex (RISC) thus mediating RNAi function, a regulator of mRNA splicing, editing and stability, and plays a role in maintenance of cell viability. Such diverse actions allow the SND1 to modulate a complex array of molecular networks, thereby promoting carcinogenesis. Here, we describe the crucial role of SND1 in cancer development and progression, and highlight SND1 as a potential target for therapeutic intervention.

Ototoxic effects of irradiation

In this study ototoxic effect of ionizing radiation was studied in 70 ears with minimum follow up of 6 months post radiotherapy. Patients of nasopharyngeal carcinoma and with conductive deafness pre radiotherapy were excluded from the study to eliminate mechanical obstruction that may play role in Eustachian tube dysfunction. We found that Eustachian tube dysfunction and conductive deafness were reversible where as Sensorineural hearing loss was an irreversible effect of radiotherapy. Dose of radiation was directly proportional to ototoxicity, minimum 60 Gys of total radiation dose was required to produce significant ototoxicity.

A pilot study to examine the feasibility of insulin glargine in subjects with impaired fasting glucose, impaired glucose tolerance or new-onset type 2 diabetes

OBJECTIVE

People with early type 2 diabetes and pre-diabetes (impaired glucose tolerance [IGT] and/or impaired fasting glucose [IFG]) are at risk of hyperglycaemia-related complications, including cardiovascular disease. Insulin, traditionally reserved as late treatment in type 2 diabetes, may also be a useful therapy in this population. We examined the short-term efficacy and tolerability of insulin glargine (glargine) in individuals with early or pre-type 2 diabetes.

RESEARCH DESIGN AND METHODS

In this multicentre, double-blind, placebo-controlled, randomized, parallel group, 12-day study, subjects with IGT/IFG (n=9), newly diagnosed type 2 diabetes (n=9) or normal glucose tolerance (n=3) (confined to a clinical research unit taking a prescribed diet) were randomized to once-daily glargine (n=16) or placebo (saline; n=5) at bedtime. Dose was titrated to achieve target fasting blood glucose (FBG) 80-95 mg/dL.

RESULTS

Over the treatment period, mean FBG decreased in glargine-treated subjects (from 100.0+/-18.8 to 85.6+/-18.4 mg/dL), but was unchanged in placebo-treated subjects (from 112.5+/-10.6 to 111.3+/-17.5 mg/dL). Mean eight-point blood glucose value decreased by 9.7 mg/dL in the glargine group, but increased by 8.1 mg/dL in the placebo group. Mean post-exercise blood glucose was similar before and after glargine treatment, but increased after placebo treatment. Five subjects receiving glargine experienced 16 mild symptomatic hypoglycaemia episodes; however, no hypoglycaemia occurred during exercise. Mean body weight decreased in both the glargine (-0.44 kg) and placebo (-0.25 kg) groups, in line with dietary restrictions.

CONCLUSIONS

The results of this pilot study suggest that glargine can be used by people with IFG, IGT or new-onset type 2 diabetes for management of hyperglycaemia with low risk of hypoglycaemia. However titration of insulin in people on dietary restrictions should be more cautious as they may be more prone to hypoglycaemia. Further studies are warranted to determine the clinical benefits of this approach.

Novel cytokine release inhibitors. Part II: Steroids

Steroidal derivatives as IL-1 beta release inhibitors are discussed.

Inhibition of IL-1 release from human monocytes and suppression of streptococcal cell wall and adjuvant-induced arthritis in rats by an extract of Tripterygium wilfordii Hook

1. It was investigated whether an extract of Tripterygium wilfordii Hook f (TW) inhibits IL-1 production by monocytes and suppresses the development of IL-1-dependent arthritis induced in rats with streptococcal cell wall and adjuvant. 2. TW preferentially inhibited IL-1 alpha and IL-1 beta production by bacterial lipopolysaccharide (LPS)-stimulated human monocytes with IC50 of approximately 1 microgram/ml. 3. Oral administration of TW dose-dependently suppressed joint swelling and structural damage in streptococcal cell wall-induced arthritis (ED50 = 20 mg/kg/day) and in adjuvant-induced arthritis (ED50 = 46 mg/kg/day for developing and 8 mg/kg/day for established arthritis).

Antigen- and ionophore-induced signal transduction in rat basophilic leukemia cells involves protein tyrosine phosphorylation

Treatment of rat basophilic leukemia cells (RBL-2H3) with antigen or ionophore leads to an increase in cellular protein tyrosine phosphorylation. Three major proteins of molecular mass of 72, 92, and 110 kDa are targeted by antigen and a 110-kDa species by ionophore, A23187. The antigen- and ionophore-induced tyrosine phosphorylation responses are dose-dependent and correlate with increases in serotonin release from activated cells. The presence of extracellular Ca2+ is required to sustain the antigen- and ionophore-stimulated tyrosine phosphorylation as well as mediator release. A protein tyrosine kinase inhibitor, RG 50864, differentially inhibits the antigen-stimulated tyrosine phosphorylation in the decreasing order of 72, 91, and 110-kDa proteins. The compound inhibition of the 72-kDa protein tyrosine phosphorylation correlates with that of serotonin release. In ionophore-stimulated cells, the inhibition of the 110-kDa protein tyrosine phosphorylation and serotonin release by RG 50864 occurs in parallel. These results suggest that the 72- and 110-kDa phosphoproteins may represent the respective regulators of serotonin release in antigen- and ionophore-activated cells. The 110-kDa tyrosine phosphorylated proteins from antigen- and ionophore-stimulated cells exhibit identical electrophoretic mobility and V8 protease-generated phosphopeptide maps, suggesting that these two proteins may be the same. These results provide new evidence that both the stimulatory actions of antigen and ionophore on mediator release are mediated through enhanced protein tyrosine phosphorylation in RBL-2H3 cells. Significantly, the present study suggests the presence of multiple tyrosine phosphorylation signaling pathways in RBL cells and that their selective utility may be determined by the nature of the stimulus.

The inhibition of 5-lipoxygenase by RG 6866

The generation of leukotrienes C4, D4 and E4 from arachidonic acid is dependent upon the activity of 5-lipoxygenase (5-LOX). The effects of RG 6866 (N-methyl-4-benzyloxyphenylacetohydroxamic acid) on the activity of guinea pig 5-LOX in vitro and in vivo were determined in the present study. The generation of 5-hydroxy-6,8,11,14-eicosatetraenoic acid (5-HETE) from arachidonic acid by isolated guinea pig peritoneal polymorphonuclear (PMN) cells was inhibited by incubation with RG 6866 (IC50 = 0.20 microM). A similar effect (IC50 = 0.23 microM) was observed when 5-HETE production was measured in a supernatant fraction from PMNs. Additionally, the compound did not inhibit 3H-LTD4 binding to guinea pig membranes. In actively sensitized guinea pigs pretreated with indomethacin, propranolol and pyrilamine, RG 6866 inhibited antigen-induced systemic anaphylaxis and LTD4-dependent bronchoconstriction in a dose-dependent manner following oral administration. In the pulmonary anaphylaxis model, significant (p less than 0.05) inhibition of the mortality was observed within 30 min and maintained through four hours after treatment with RG 6866 (50 mg/kg i.g.). Finally, orally administered RG 6866 inhibited the formation of LTC4 in these animals with an ED50 = 24.0 mg/kg. These findings indicate that RG 6866 is an inhibitor of 5-LOX both in vitro and in vivo.

Antiallergic activity profiles in vitro of RHC 3164 and related compounds. I. A lack of correlation between inhibition of cyclic nucleotide phosphodiesterases and antigen-induced release of histamine from rat mast cells

A series of 26 compounds belonging to the chemical class of (1,2,4)triazolo(4,3-a)-quinoxaline-1,4-diones have been investigated for their antiallergic activities in 3 in vitro models of anaphylaxis. Effects of these and other known antiallergic agents on cyclic nucleotide phosphodiesterases (cNUC-PDE) from purified rat mast cells have also been investigated. 18 compounds were potent (I50 less than or equal to 45 microM) inhibitors of antigen-induced release of histamine (AIR) from rat mast cells (RMC), 3 compounds inhibited anti-IgE-induced release of histamine from human basophils (I50 less than or equal to 25 microM) and none of the compounds significantly affected AIR from guinea pig lung slices. 13 of the compounds were more potent than theophylline as inhibitors of cyclic AMP-PDE and/or cyclic GMP-PDE from RMC. Parallel concentration-response curves for the inhibition of cyclic AMP-PDE and cyclic GMP-PDE indicated that these compounds probably interact with enzyme in the same manner. Paired regression analysis of the I50 values for inhibition of AIR and cNUC-PDE from RMC by these compounds revealed no statistically significant correlation between the inhibition of AIR and inhibition of cyclic AMP-PDE or cyclic GMP-PDE. We conclude: (1) some of these compounds are potent inhibitors of immunologic release of histamine from RMC with an in vitro activity profile similar to that of DSCG, and (2) inhibition of cyclic AMP or cyclic GMP hydrolysis by cNUD-PDE by these compounds, DSCG, and 6 known antiallergic agents is not the biochemical mechanism by which they inhibit AIR from RMC.

Antiallergic activity profiles in vitro of RHC 3164 and related compounds. II. Comparison of RHC 3164 with disodium cromoglycate

RHC 3164 has been investigated for its antiallergic activities in 3 in vitro models of anaphylaxis. RHC 3164 was 6 times more potent than DSCG as an inhibitor of antigen-induced release of histamine (AIR) from rat mast cells (RMC) and had an activity profile identical to that of DSCG in the following respects: loss of inhibitory activity with increasing preincubation time, tachyphylactic properties, cross-tachyphylaxis to DSCG, and inability to inhibit nonimmunologic release of histamine. Neither RHC 3164 nor DSCG had any effect on immunologic release of histamine from human basophils or guinea pig lung slices. We conclude that RHC 3164 is a potent inhibitor of immunologic release of histamine from RMC with a mechanism of action similar to that of DSCG.

RHC 3288 [1-methyl-2(1,3,4-oxadiazol-2(3H)-one-5-yl) benzimidazole] and related compounds. Novel inhibitors of histamine release from rat mast cells and human basophils

RHC 3288 [1-methyl-2(1,3,4-oxadiazol-2(3H)-one-5-yl) benzimidazole] and twenty-five related 5-substituted oxadiazolones have been investigated for their antiallergic activities in three in vitro models of anaphylaxis. Sixteen compounds were potent (I50 less than or equal to 50 microM) inhibitors of antigen-induced release of histamine (AIR) from rat mast cells (RMC), and seven compounds inhibited anti-IgE-induced release of histamine from human basophils (I50 less than or equal to 100 microM). The antiallergic activity profiles of RHC 3288 and three other compounds in these models have been compared with that of disodium cromoglycate (DSCG). As inhibitors of AIR from RMC, RHC 3288, 3334, 3354 and 3380 were 3 to 10 times more potent than DSCG. In the same model (AIR from RMC), activity profiles of all four RHC compounds were identical to that of DSCG in the following respects: loss of inhibitory activity with increasing preincubation time, tachyphylaxis and cross-tachyphylaxis to each other, and inability to inhibit histamine release stimulated by Ca2+ ionophore, dextran + phosphatidyl serine and compound 48/80. RHC 3288, 3334, 3354 and DSCG had no effect in the other two models, histamine release from guinea pig lung mediated predominantly by IgG1 class of antibodies and anti-IgE-induced histamine release from human basophils. We conclude that RHC 3288 is a potent inhibitor of mediator release with a mechanism of action similar to that of DSCG.

RHC 3024: antiallergic activity in vitro and comparison with disodium cromoglycate and other antiallergic agents

RHC 3024 has been investigated for its antiallergic activity in three in vitro models of anaphylaxis. We have also compared its activity profile in these models with that of disodium cromoglycate (DSCG) and other antiallergic agents. As an inhibitor of antigen-induced release of histamine from rat mast cells RHC 3024 was 4 times more potent than DSCG. In the same model the activity profile of RHC 3024 was identical to that of DSCG in the following respects: loss of inhibitory activity with increasing preincubation time, reversibility of the inhibition, tachyphylaxis and cross-tachyphylaxis to each other and inability to inhibit histamine release stimulated by Ca++ ionophore, dextran/phosphatidyl serine and compound 48/80. Both drugs had no effect in the other two models, IgG1-mediated histamine release from guinea pig lung and anti-IgE-induced histamine release from human basophils. We conclude: (1) RHC 3024 is a potent inhibitor of mediator release with a mechanism of action similar to that of DSCG, M&B 22,948, PRD-92-Ea and AH-7725 and (2) the in vitro activity profiles of proxicromil, doxantrazole, ICI 74,917 and WY-16,922 are different from DSCG and RHC 3024.