How Mixed-Methods Research Can Improve the Policy Relevance of Impact Evaluations.

This paper describes how mixed methods can improve the value and policy relevance of impact evaluations, paying particular attention to how mixed methods can be used to address external validity and generalization issues. We briefly review the literature on the rationales for using mixed methods; provide documentation of the extent to which mixed methods have been used in impact evaluations in recent years; describe how we developed a list of recent impact evaluations using mixed methods and the process used to conduct full-text reviews of these articles; summarize the findings from our analysis of the articles; discuss three exemplars of using mixed methods in impact evaluations; and discuss how mixed methods have been used for studying and improving external validity and potential improvements that could be made in this area. We find that mixed methods are rarely used in impact evaluations, and we believe that increased use of mixed methods would be useful because they can reinforce findings from the quantitative analysis (triangulation), and they can also help us understand the mechanism by which programs have their impacts and the reasons why programs fail.

Inflammatory Myofibroblastic Tumor With Rapid Recurrence and Distant Metastasis: Report of a Rare Case.

Inflammatory myofibroblastic tumors (IMTs) are rare spindle cell tumors clinically, morphologically, and genetically heterogeneous, mimicking many other reactive and neoplastic lesions and creating great diagnostic problems. Although it is generally characterized by oncogene-derived proliferation of myofibroblasts in a background of polyclonal inflammatory cell infiltrates, morphological variations do occur requiring immunohistochemistry and molecular genetics to confirm the diagnosis. It encompasses a wide age range, and locations, mostly said to be of intermediate grade having a low risk of recurrence and metastasis. However, its biological behavior and course are variable and unpredictable. Here, we report a case of thoracic IMT in a 32-year-old adult female presenting with a history of fever, cough, and chest pain associated with neutrophilic leukocytosis. Radiological investigations revealed a large mass in the thoracic region with possibilities of hydatid cyst and neurogenic tumor. Initial core needle biopsy specimen and subsequent local resection specimen revealed the diagnosis of IMT on histopathology and immunohistochemistry, having conventional morphology with expression of Anaplastic lymphoma kinase (ALK) protein. The patient developed rapid local recurrence and was started with first-generation ALK inhibitor Crizotinib. After a brief period of response, she developed vertebral and brain metastasis within a short span of time and was switched to a third-generation ALK inhibitor, Lorlatinib. The patient is on regular follow-up, has stable disease, and maintains a good quality of life after two years of diagnosis.

We Know the Yin-But Where Is the Yang? Toward a Balanced Approach on Common Source Bias in Public Administration Scholarship.

Surveys have long been a dominant instrument for data collection in public administration. However, it has become widely accepted in the last decade that the usage of a self-reported instrument to measure both the independent and dependent variables results in common source bias (CSB). In turn, CSB is argued to inflate correlations between variables, resulting in biased findings. Subsequently, a narrow blinkered approach on the usage of surveys as single data source has emerged. In this article, we argue that this approach has resulted in an unbalanced perspective on CSB. We argue that claims on CSB are exaggerated, draw upon selective evidence, and project what should be tentative inferences as certainty over large domains of inquiry. We also discuss the perceptual nature of some variables and measurement validity concerns in using archival data. In conclusion, we present a flowchart that public administration scholars can use to analyze CSB concerns.

Targeting KRAS-dependent tumors with AZD4785, a high-affinity therapeutic antisense oligonucleotide inhibitor of KRAS.

Activating mutations in KRAS underlie the pathogenesis of up to 20% of human tumors, and KRAS is one of the most frequently mutated genes in cancer. Developing therapeutics to block KRAS activity has proven difficult, and no direct inhibitor of KRAS function has entered clinical trials. We describe the preclinical evaluation of AZD4785, a high-affinity constrained ethyl-containing therapeutic antisense oligonucleotide (ASO) targeting KRAS mRNA. AZD4785 potently and selectively depleted cellular KRAS mRNA and protein, resulting in inhibition of downstream effector pathways and antiproliferative effects selectively in KRAS mutant cells. AZD4785-mediated depletion of KRAS was not associated with feedback activation of the mitogen-activated protein kinase (MAPK) pathway, which is seen with RAS-MAPK pathway inhibitors. Systemic delivery of AZD4785 to mice bearing KRAS mutant non-small cell lung cancer cell line xenografts or patient-derived xenografts resulted in inhibition of KRAS expression in tumors and antitumor activity. The safety of this approach was demonstrated in mice and monkeys with KRAS ASOs that produced robust target knockdown in a broad set of tissues without any adverse effects. Together, these data suggest that AZD4785 is an attractive therapeutic for the treatment of KRAS-driven human cancers and warrants further development.

Targeting DMPK with Antisense Oligonucleotide Improves Muscle Strength in Myotonic Dystrophy Type 1 Mice.

Myotonic dystrophy type 1 (DM1), a dominant hereditary muscular dystrophy, is caused by an abnormal expansion of a (CTG)n trinucleotide repeat in the 3' UTR of the human dystrophia myotonica protein kinase (DMPK) gene. As a consequence, mutant transcripts containing expanded CUG repeats are retained in nuclear foci and alter the function of splicing regulatory factors members of the MBNL and CELF families, resulting in alternative splicing misregulation of specific transcripts in affected DM1 tissues. In the present study, we treated DMSXL mice systemically with a 2'-4'-constrained, ethyl-modified (ISIS 486178) antisense oligonucleotide (ASO) targeted to the 3' UTR of the DMPK gene, which led to a 70% reduction in CUGexp RNA abundance and foci in different skeletal muscles and a 30% reduction in the heart. Furthermore, treatment with ISIS 486178 ASO improved body weight, muscle strength, and muscle histology, whereas no overt toxicity was detected. This is evidence that the reduction of CUGexp RNA improves muscle strength in DM1, suggesting that muscle weakness in DM1 patients may be improved following elimination of toxic RNAs.

Dmpk gene deletion or antisense knockdown does not compromise cardiac or skeletal muscle function in mice.

Myotonic dystrophy type 1 (DM1) is a genetic disorder in which dominant-active DM protein kinase (DMPK) transcripts accumulate in nuclear foci, leading to abnormal regulation of RNA processing. A leading approach to treat DM1 uses DMPK-targeting antisense oligonucleotides (ASOs) to reduce levels of toxic RNA. However, basal levels of DMPK protein are reduced by half in DM1 patients. This raises concern that intolerance for further DMPK loss may limit ASO therapy, especially since mice with Dmpk gene deletion reportedly show cardiac defects and skeletal myopathy. We re-examined cardiac and muscle function in mice with Dmpk gene deletion, and studied post-maturity knockdown using Dmpk-targeting ASOs in mice with heterozygous deletion. Contrary to previous reports, we found no effect of Dmpk gene deletion on cardiac or muscle function, when studied on two genetic backgrounds. In heterozygous knockouts, the administration of ASOs reduced Dmpk expression in cardiac and skeletal muscle by > 90%, yet survival, electrocardiogram intervals, cardiac ejection fraction and muscle strength remained normal. The imposition of cardiac stress by pressure overload, or muscle stress by myotonia, did not unmask a requirement for DMPK. Our results support the feasibility and safety of using ASOs for post-transcriptional silencing of DMPK in muscle and heart.

Identification and characterization of modified antisense oligonucleotides targeting DMPK in mice and nonhuman primates for the treatment of myotonic dystrophy type 1.

Myotonic dystrophy type 1 (DM1) is the most common form of muscular dystrophy in adults. DM1 is caused by an expanded CTG repeat in the 3'-untranslated region of DMPK, the gene encoding dystrophia myotonica protein kinase (DMPK). Antisense oligonucleotides (ASOs) containing 2',4'-constrained ethyl-modified (cEt) residues exhibit a significantly increased RNA binding affinity and in vivo potency relative to those modified with other 2'-chemistries, which we speculated could translate to enhanced activity in extrahepatic tissues, such as muscle. Here, we describe the design and characterization of a cEt gapmer DMPK ASO (ISIS 486178), with potent activity in vitro and in vivo against mouse, monkey, and human DMPK. Systemic delivery of unformulated ISIS 486718 to wild-type mice decreased DMPK mRNA levels by up to 90% in liver and skeletal muscle. Similarly, treatment of either human DMPK transgenic mice or cynomolgus monkeys with ISIS 486178 led to up to 70% inhibition of DMPK in multiple skeletal muscles and ∼50% in cardiac muscle in both species. Importantly, inhibition of DMPK was well tolerated and was not associated with any skeletal muscle or cardiac toxicity. Also interesting was the demonstration that the inhibition of DMPK mRNA levels in muscle was maintained for up to 16 and 13 weeks post-treatment in mice and monkeys, respectively. These results demonstrate that cEt-modified ASOs show potent activity in skeletal muscle, and that this attractive therapeutic approach warrants further clinical investigation to inhibit the gain-of-function toxic RNA underlying the pathogenesis of DM1.

Effect of 2'-O-[2-[2-(N,N-dimethylamino)ethoxy]ethyl] modification on activity of gapmer antisense oligonucleotides containing 2',4'-constrained 2'-O-ethyl nucleic acid.

We evaluated the effect of combining 2'-O-[2-[2-(N,N-dimethylamino)ethoxy]ethyl] (2'-O-DMAEOE), a 2'-cationic modification, with a 2',4'-constrained 2'-O-ethyl nucleic acid (cEt BNA) on the activity of an antisense oligonucleotide (ASO) using PTEN as a model target. Our results suggest that replacing one cEt BNA nucleotide with 2'-O-DMAEOE nucleotide at the 5'-end of a 2-10-2 gapmer ASO maintained the potency relative to parent ASO in liver. The cationic 2'-O-DMAEOE modification did not improve the activity of ASO in extra-hepatic tissues. Results from this study provide guidance to design improved antisense oligonucleotide drugs.

Synthesis and antisense properties of 2'-O-(2S-methoxypropyl)-RNA-modified gapmer antisense oligonucleotides.

To ascertain whether increasing hydrophobicity can enhance the activity of second-generation antisense oligonucleotides (ASOs) in muscle, we investigated the antisense properties of 2'-O-(2S-methoxypropyl)-RNA (2S-MOP)-modified ASOs. Synthesis of the 2S-MOP 5-methyl uridine phosphoramidite was accomplished on a multi-gram scale by Lewis-acid-catalyzed ring opening of 5'-O-tert-butyldiphenylsilyl ether-protected 2,2'-anhydro-5-methyl uridine with 2S-methoxy-1-propanol. Synthesis of the 2S-MOP 5-methyl cytidine nucleoside from the corresponding 5-methyl uridine nucleoside was accomplished by formation and displacement of a 4-triazolide intermediate with aqueous ammonia. 2S-MOP-modified oligonucleotides were prepared on an automated DNA synthesizer and showed similar enhancements in duplex thermal stability as 2'-O-methoxyethyl RNA (MOE)-modified oligonucleotides. 2S-MOP-containing antisense oligonucleotides were evaluated in Balb-c mice and showed good activity for decreasing the expression levels of scavenger receptor B1 (Srb1) and phosphatase and tensin homologue (PTEN) mRNA in liver and muscle tissue.

Targeting nuclear RNA for in vivo correction of myotonic dystrophy.

Antisense oligonucleotides (ASOs) hold promise for gene-specific knockdown in diseases that involve RNA or protein gain-of-function effects. In the hereditary degenerative disease myotonic dystrophy type 1 (DM1), transcripts from the mutant allele contain an expanded CUG repeat and are retained in the nucleus. The mutant RNA exerts a toxic gain-of-function effect, making it an appropriate target for therapeutic ASOs. However, despite improvements in ASO chemistry and design, systemic use of ASOs is limited because uptake in many tissues, including skeletal and cardiac muscle, is not sufficient to silence target messenger RNAs. Here we show that nuclear-retained transcripts containing expanded CUG (CUG(exp)) repeats are unusually sensitive to antisense silencing. In a transgenic mouse model of DM1, systemic administration of ASOs caused a rapid knockdown of CUG(exp) RNA in skeletal muscle, correcting the physiological, histopathologic and transcriptomic features of the disease. The effect was sustained for up to 1 year after treatment was discontinued. Systemically administered ASOs were also effective for muscle knockdown of Malat1, a long non-coding RNA (lncRNA) that is retained in the nucleus. These results provide a general strategy to correct RNA gain-of-function effects and to modulate the expression of expanded repeats, lncRNAs and other transcripts with prolonged nuclear residence.

Reduced adiposity and improved insulin sensitivity in obese mice with antisense suppression of 4E-BP2 expression.

To investigate the possible role of eukaryotic initiation factor 4E-binding protein-2 (4E-BP2) in metabolism and energy homeostasis, high-fat diet-induced obese mice were treated with a 4E-BP2-specific antisense oligonucleotide (ASO) or a control 4E-BP2 ASO at a dose of 25 mg/kg body wt or with saline twice a week for 6 wk. 4E-BP2 ASO treatment reduced 4E-BP2 levels by >75% in liver and white (WAT) and brown adipose (BAT) tissues. Treatment did not change food intake but lowered body weight by approximately 7% and body fat content by approximately 18%. Treatment decreased liver triglyceride (TG) content by >50%, normalized plasma glucose and insulin levels, and reduced glucose excursion during glucose tolerance test. 4E-BP2 ASO-treated mice showed >8.5% increase in metabolic rate, >40% increase in UCP1 levels in BAT, >45% increase in beta(3)-adrenoceptor mRNA, and 40-55% decrease in mitochondrial dicarboxylate carrier, fatty acid synthase, and diacylglycerol acyltransferase 2 mRNA levels in WAT. 4E-BP2 ASO-transfected mouse hepatocytes showed an increased fatty acid oxidation rate and a decreased TG synthesis rate. In addition, 4E-BP2 ASO-treated mice demonstrated approximately 60 and 29% decreases in hepatic glucose-6-phosphatase and phosphoenolpyruvate carboxykinase mRNA, respectively, implying decreased hepatic glucose output. Furthermore, increased phosphorylation of Akt(Ser473) in both liver and fat of 4E-BP2 ASO-treated mice and increased GLUT4 levels in plasma membrane in WAT of the ASO-treated mice were observed, indicating enhanced insulin signaling and increased glucose uptake as a consequence of reduced 4E-BP2 expression. These data demonstrate for the first time that peripheral 4E-BP2 plays an important role in metabolism and energy homeostasis.

Diacylglycerol acyltranferase 1 anti-sense oligonucleotides reduce hepatic fibrosis in mice with nonalcoholic steatohepatitis.

UNLABELLED: Retinyl ester (RE) stores decrease during hepatic stellate cell (HSC) activation and liver fibrosis. Although retinol esterification is mostly catalyzed by lecithin:retinol acyltransferase (LRAT), diacylglycerol acyltransferase (DGAT)1 also does this. In previous reports, LRAT(-/-) mice had reduced hepatic RE but neither excessive HSC activation nor liver fibrosis, and DGAT1(-/-) mice had increased liver levels of RE and retinol. We sought to clarify the role of DGAT1 in liver fibrosis. Expression of DGAT1/2 was compared by real time PCR in freshly isolated, primary mouse HSCs and hepatocytes. To induce nonalcoholic steatohepatitis (NASH) and liver fibrosis, adult male db/db mice were fed methionine choline-deficient (MCD) diets. Half were treated with DGAT1 antisense oligonucleotide (ASO); the rest were injected with saline. Results were compared with chow-fed controls. Inhibition of DGAT1 in liver had no effect on hepatic triglyceride content or liver necroinflammation but reduced HSC activation and liver fibrosis in mice with NASH. To evaluate the role of DGAT1 in HSC activation, HSC were isolated from healthy rats treated with DGAT1 ASO or saline. DGAT1 was expressed at relatively high levels in HSCs. HSC isolated from DGAT1 ASO-treated rats had reduced DGAT1 expression and increased messenger RNA (mRNA) levels of LRAT and cellular retinol binding protein-1. During culture, they retained more vitamin A, had repressed collagen a2 (I) transcriptional activity, and expressed less collagen a1 (I) and a2 (I) mRNA. CONCLUSION: DGAT1 may be a therapeutic target in NASH because inhibiting DGAT1 favorably altered. HSC retinoid homeostasis and inhibited hepatic fibrosis in mice with NASH.

Suppression of diacylglycerol acyltransferase-2 (DGAT2), but not DGAT1, with antisense oligonucleotides reverses diet-induced hepatic steatosis and insulin resistance.

Nonalcoholic fatty liver disease (NAFLD) is a major contributing factor to hepatic insulin resistance in type 2 diabetes. Diacylglycerol acyltransferase (Dgat), of which there are two isoforms (Dgat1 and Dgat2), catalyzes the final step in triglyceride synthesis. We evaluated the metabolic impact of pharmacological reduction of DGAT1 and -2 expression in liver and fat using antisense oligonucleotides (ASOs) in rats with diet-induced NAFLD. Dgat1 and Dgat2 ASO treatment selectively reduced DGAT1 and DGAT2 mRNA levels in liver and fat, but only Dgat2 ASO treatment significantly reduced hepatic lipids (diacylglycerol and triglyceride but not long chain acyl CoAs) and improved hepatic insulin sensitivity. Because Dgat catalyzes triglyceride synthesis from diacylglycerol, and because we have hypothesized that diacylglycerol accumulation triggers fat-induced hepatic insulin resistance through protein kinase C epsilon activation, we next sought to understand the paradoxical reduction in diacylglycerol in Dgat2 ASO-treated rats. Within 3 days of starting Dgat2 ASO therapy in high fat-fed rats, plasma fatty acids increased, whereas hepatic lysophosphatidic acid and diacylglycerol levels were similar to those of control rats. These changes were associated with reduced expression of lipogenic genes (SREBP1c, ACC1, SCD1, and mtGPAT) and increased expression of oxidative/thermogenic genes (CPT1 and UCP2). Taken together, these data suggest that knocking down Dgat2 protects against fat-induced hepatic insulin resistance by paradoxically lowering hepatic diacylglycerol content and protein kinase C epsilon activation through decreased SREBP1c-mediated lipogenesis and increased hepatic fatty acid oxidation.

Inhibiting triglyceride synthesis improves hepatic steatosis but exacerbates liver damage and fibrosis in obese mice with nonalcoholic steatohepatitis.

UNLABELLED: In the early stages of nonalcoholic fatty liver disease (NAFLD), triglycerides accumulate in hepatocytes. Diacylglycerol acyltransferase 2 (DGAT2) catalyzes the final step in hepatocyte triglyceride biosynthesis. DGAT2 antisense oligonucleotide (ASO) treatment improved hepatic steatosis dramatically in a previous study of obese mice. According to the 2-hit hypothesis for progression of NAFLD, hepatic steatosis is a risk factor for nonalcoholic steatohepatitis (NASH) and fibrosis. To evaluate this hypothesis, we inhibited DGAT2 in a mouse model of NASH induced by a diet deficient in methionine and choline (MCD). Six-week-old genetically obese and diabetic male db/db mice were fed either the control or the MCD diet for 4 or 8 weeks. The MCD diet group was treated with either 25 mg/kg DGAT2 ASO or saline intraperitoneally twice weekly. Hepatic steatosis, injury, fibrosis, markers of lipid peroxidation/oxidant stress, and systemic insulin sensitivity were evaluated. Hepatic steatosis, necroinflammation, and fibrosis were increased in saline-treated MCD diet-fed mice compared to controls. Treating MCD diet-fed mice with DGAT2 ASO for 4 and 8 weeks decreased hepatic steatosis, but increased hepatic free fatty acids, cytochrome P4502E1, markers of lipid peroxidation/oxidant stress, lobular necroinflammation, and fibrosis. Progression of liver damage occurred despite reduced hepatic expression of tumor necrosis factor alpha, increased serum adiponectin, and striking improvement in systemic insulin sensitivity. CONCLUSION: Results from this mouse model would suggest accumulation of triglycerides may be a protective mechanism to prevent progressive liver damage in NAFLD.

Reduction of low molecular weight protein-tyrosine phosphatase expression improves hyperglycemia and insulin sensitivity in obese mice.

To investigate the role of low molecular weight protein-tyrosine phosphatase (LMW-PTP) in glucose metabolism and insulin action, a specific antisense oligonucleotide (ASO) was used to reduce its expression both in vitro and in vivo. Reduction of LMW-PTP expression with the ASO in cultured mouse hepatocytes and in liver and fat tissues of diet-induced obese (DIO) mice and ob/ob mice led to increased phosphorylation and activity of key insulin signaling intermediates, including insulin receptor-beta subunit, phosphatidylinositol 3-kinase, and Akt in response to insulin stimulation. The ASO-treated DIO and ob/ob animals showed improved insulin sensitivity, which was reflected by a lowering of both plasma insulin and glucose levels and improved glucose and insulin tolerance in DIO mice. The treatment did not decrease body weight or increase metabolic rate. These data demonstrate that LMW-PTP is a key negative regulator of insulin action and a potential novel target for the treatment of insulin resistance and type 2 diabetes.

Involvement of insulin-like growth factor type 1 receptor and protein kinase Cdelta in bis(maltolato)oxovanadium(IV)-induced phosphorylation of protein kinase B in HepG2 cells.

Vanadium(IV) oxo-bis(maltolato) (BMOV), an organovanadium compound, is a potent insulinomimetic agent and improves glucose homeostasis in various models of diabetes. We have shown previously that BMOV stimulates the phosphorylation of PKB which may contribute as one of the mechanisms for the insulinomimetic effect of this compound. However, the upstream mechanism of BMOV-induced PKB phosphorylation remains elusive. Therefore, in this study, we examine the upstream events leading to BMOV-induced PKB phosphorylation in HepG2 cells. Since BMOV is an inhibitor of protein tyrosine phosphatases and through enhanced tyrosine phosphorylation may activate various protein tyrosine kinases (PTK), we have investigated the potential role of different receptor or nonreceptor PTK in mediating BMOV-induced PKB phosphorylation. Among several pharmacological inhibitors that were tested, only AG1024, a selective inhibitor of IGF-1R-PTK, almost completely blocked BMOV-stimulated phosphorylation of PKB. In contrast, AG1295 and AG1478, specific inhibitors of PDGFR and EGFR, respectively, were unable to block the BMOV response. Moreover, efficient reduction of the level of IGF-1R protein expression by antisense oligonucleotides (ASO) attenuated BMOV-induced PKB phosphorylation. BMOV-induced PKB phosphorylation was associated with an increased level of tyrosine phosphorylation of the IRbeta subunit, IGF-1Rbeta subunit, IRS-1, and p85alpha subunit of PI3-kinase. However, this response was independent of IR-PTK activity because in cells overexpressing a PTK-inactive form of IR, insulin response was attenuated while the effect of BMOV remained intact. A role of PKC in BMOV-induced response was also tested. Pharmacological inhibition with chelerythrine, a nonselective PKC inhibitor, or rottlerin, a PKCdelta inhibitor, as well as chronic treatment with PMA attenuated BMOV-induced PKB phosphorylation. In contrast, GO6976 and RO31-8220 PKCalpha/beta selective inhibitors failed to alter the BMOV effect. Taken together, these data suggest that IGF-1R and PKCdelta are required to stimulate PKB phosphorylation in response to BMOV in HepG2 cells and provide new insights into the molecular mechanism by which this compound exerts its insulinomimetic effects.

miR-122 regulation of lipid metabolism revealed by in vivo antisense targeting.

Current understanding of microRNA (miRNA) biology is limited, and antisense oligonucleotide (ASO) inhibition of miRNAs is a powerful technique for their functionalization. To uncover the role of the liver-specific miR-122 in the adult liver, we inhibited it in mice with a 2'-O-methoxyethyl phosphorothioate ASO. miR-122 inhibition in normal mice resulted in reduced plasma cholesterol levels, increased hepatic fatty-acid oxidation, and a decrease in hepatic fatty-acid and cholesterol synthesis rates. Activation of the central metabolic sensor AMPK was also increased. miR-122 inhibition in a diet-induced obesity mouse model resulted in decreased plasma cholesterol levels and a significant improvement in liver steatosis, accompanied by reductions in several lipogenic genes. These results implicate miR-122 as a key regulator of cholesterol and fatty-acid metabolism in the adult liver and suggest that miR-122 may be an attractive therapeutic target for metabolic disease.

Insulin signal mimicry as a mechanism for the insulin-like effects of vanadium.

Among several metals, vanadium has emerged as an extremely potent agent with insulin-like properties. These insulin-like properties have been demonstrated in isolated cells, tissues, different animal models of type I and type II diabetes as well as a limited number of human subjects. Vanadium treatment has been found to improve abnormalities of carbohydrate and lipid metabolism and of gene expression in rodent models of diabetes. In isolated cells, it enhances glucose transport, glycogen and lipid synthesis, and inhibits gluconeogenesis and lipolysis. The molecular mechanism responsible for the insulin-like effects of vanadium compounds have been shown to involve the activation of several key components of insulin-signaling pathways that include the mitogen-activated-protein kinases (MAPKs) extracellular signal-regulated kinase 1/2 (ERK1/2) and p38MAPK, and phosphatidylinositol 3-kinase (PI3-K)/protein kinase B (PKB). It is interesting that the vanadium effect on these signaling systems is independent of insulin receptor protein tyrosine kinase activity, but it is associated with enhanced tyrosine phosphorylation of insulin receptor substrate-1. These actions seem to be secondary to vanadium-induced inhibition of protein tyrosine phosphatases. Because MAPK and PI3-K/PKB pathways are implicated in mediating the mitogenic and metabolic effects of insulin, respectively, it is plausible that mimicry of these pathways by vanadium serves as a mechanism for its insulin-like responses.

Binding of manumycin A inhibits IkappaB kinase beta activity.

IkappaB kinase (IKK) catalytic subunits play a key role in cytokinemediated nuclear factor (NF)-kappaB signaling, and a loss of NF-kappaB function appears to inhibit inflammation and oncogenesis. Manumycin A is a potent and selective farnesyltransferase inhibitor with antitumor activity. We found that manumycin A caused a rapid and potent inhibition of IKK activity induced by tumor necrosis factor alpha in a number of cell types. Most unexpectedly, other classes of farnesyltransferase inhibitors had no inhibitory effect. To identify the molecular mechanisms of manumycin A action, cultured human HepG2 hepatoma cells were transiently transfected with various IKKalpha and IKKbeta constructs, and a striking difference in manumycin A sensitivity was observed. Furthermore, cells expressing wild-type IKKbeta and IKKbeta mutated in the activation loop at Cys-179 exhibited covalent homotypic dimerization of IKKbeta in response to manumycin A, whereas substitution of Cys-662 and -716 conferred protection against dimer formation. Direct inhibition of IKK activity and formation of stable IKKbeta dimers were observed in the presence of manumycin A that could be blocked by dithiothreitol. IKK interaction with the adaptor protein IKKgamma/NEMO was disrupted in manumycin A-treated cells. Most importantly, administration of manumycin A to mice xenografted with murine B16F10 tumors caused potent IKK-suppressive effects. Thus, manumycin A with its epoxyquinoid moieties plays an important regulatory function in IKK signaling through pathways distinct from its role as a protein farnesylation inhibitor.

Antisense oligonucleotide reduction of DGAT2 expression improves hepatic steatosis and hyperlipidemia in obese mice.

In this study, we investigated the role of acyl-coenzyme A:diacylglycerol acyltransferase 2 (DGAT2) in glucose and lipid metabolism in obese mice by reducing its expression in liver and fat with an optimized antisense oligonucleotide (ASO). High-fat diet-induced obese (DIO) C57BL/6J mice and ob/ob mice were treated with DGAT2 ASO, control ASO, or saline. DGAT2 ASO treatment reduced DGAT2 messenger RNA (mRNA) levels by more than 75% in both liver and fat but did not change DGAT1 mRNA levels in either of these tissues, which resulted in decreased DGAT activity in liver but not in fat. DGAT2 ASO treatment did not cause significant changes in body weight, adiposity, metabolic rate, insulin sensitivity, or skin microstructure. However, DGAT2 ASO treatment caused a marked reduction in hepatic triglyceride content and improved hepatic steatosis in both models, which was consistent with a dramatic decrease in triglyceride synthesis and an increase in fatty acid oxidation observed in primary mouse hepatocytes treated with DGAT2 ASO. In addition, the treatment lowered hepatic triglyceride secretion rate and plasma triglyceride levels, and improved plasma lipoprotein profile in DIO mice. The positive effects of the DGAT2 ASO were accompanied by a reduction in the mRNA levels of several hepatic lipogenic genes, including SCD1, FAS, ACC1, ACC2, ATP-citrate lyase, glycerol kinase, and HMG-CoA reductase. In conclusion, reduction of DGAT2 expression in obese animals can reduce hepatic lipogenesis and hepatic steatosis as well as attenuate hyperlipidemia, thereby leading to an improvement in metabolic syndrome.