Deletion of Elovl5 leads to dyslipidemia and atherosclerosis in LDLR-deficient mice.

Atherosclerosis is a chronic inflammatory disease for which hepatic steatosis and atherogenic dyslipidemia are significant risk factors. We investigated the effects of endogenously generated very-long-chain polyunsaturated fatty acids (VL-PUFAs) on dyslipidemia and atherosclerosis development using mice that lack ELOVL5, a PUFA elongase that is required for the synthesis of arachidonic acid, EPA, and DHA from the essential fatty acids linoleic and linolenic acids, and the LDL receptor (LDLR). Elovl5-/-;Ldlr-/- mice manifest increased liver triglyceride and cholesterol concentrations due to the activation of sterol regulatory element binding protein-1, a transcription factor that activates enzymes required for de novo lipogenesis. Plasma levels of triglycerides and cholesterol in VLDL, IDL, and LDL were markedly elevated in Elovl5-/-;Ldlr-/- mice fed a chow and the mice exhibited marked aortic atherosclerotic plaques. Bone marrow-derived monocytes from wild-type (WT) and Elovl5-/- mice were polarized to M1 and M2 macrophages, and the effects of ELOVL5 on inflammatory activity were determined. There were no differences in most of the markers tested for M1 and M2 polarized cells between WT and Elovl5-/- cells, except for a slight increase in PGE2 secretion in Elovl5-/- cells, likely due to elevated Cox-2 expression. These results suggest that the deletion of Elovl5 leads to hepatic steatosis and dyslipidemia, which are the major factors in severe atherosclerosis in Elovl5-/-;Ldlr-/- mice.

Spinocerebellar ataxia 38: structure-function analysis shows ELOVL5 G230V is proteotoxic, conformationally altered and a mutational hotspot.

Fatty acid elongase ELOVL5 is part of a protein family of multipass transmembrane proteins that reside in the endoplasmic reticulum where they regulate long-chain fatty acid elongation. A missense variant (c.689G>T p.Gly230Val) in ELOVL5 causes Spinocerebellar Ataxia subtype 38 (SCA38), a neurodegenerative disorder characterized by autosomal dominant inheritance, cerebellar Purkinje cell demise and adult-onset ataxia. Having previously showed aberrant accumulation of p.G230V in the Golgi complex, here we further investigated the pathogenic mechanisms triggered by p.G230V, integrating functional studies with bioinformatic analyses of protein sequence and structure. Biochemical analysis showed that p.G230V enzymatic activity was normal. In contrast, SCA38-derived fibroblasts showed reduced expression of ELOVL5, Golgi complex enlargement and increased proteasomal degradation with respect to controls. By heterologous overexpression, p.G230V was significantly more active than wild-type ELOVL5 in triggering the unfolded protein response and in decreasing viability in mouse cortical neurons. By homology modelling, we generated native and p.G230V protein structures whose superposition revealed a shift in Loop 6 in p.G230V that altered a highly conserved intramolecular disulphide bond. The conformation of this bond, connecting Loop 2 and Loop 6, appears to be elongase-specific. Alteration of this intramolecular interaction was also observed when comparing wild-type ELOVL4 and the p.W246G variant which causes SCA34. We demonstrate by sequence and structure analyses that ELOVL5 p.G230V and ELOVL4 p.W246G are position-equivalent missense variants. We conclude that SCA38 is a conformational disease and propose combined loss of function by mislocalization and gain of toxic function by ER/Golgi stress as early events in SCA38 pathogenesis.

Deletion of KLF10 Leads to Stress-Induced Liver Fibrosis upon High Sucrose Feeding.

Liver fibrosis is a consequence of chronic liver injury associated with chronic viral infection, alcohol abuse, and nonalcoholic fatty liver. The evidence from clinical and animal studies indicates that transforming growth factor-ß (TGF-ß) signaling is associated with the development of liver fibrosis. Krüppel-like factor 10 (KLF10) is a transcription factor that plays a significant role in TGF-ß-mediated cell growth, apoptosis, and differentiation. In recent studies, it has been reported to be associated with glucose homeostasis and insulin resistance. In the present study, we investigated the role of KLF10 in the progression of liver disease upon a high-sucrose diet (HSD) in mice. Wild type (WT) and Klf10 knockout (KO) mice were fed either a control chow diet or HSD (50% sucrose) for eight weeks. Klf10 KO mice exhibited significant hepatic steatosis, inflammation, and liver injury upon HSD feeding, whereas the WT mice exhibited mild hepatic steatosis with no apparent liver injury. The livers of HSD-fed Klf10 KO mice demonstrated significantly increased endoplasmic reticulum stress, oxidative stress, and proinflammatory cytokines. Klf10 deletion led to the development of sucrose-induced hepatocyte cell death both in vivo and in vitro. Moreover, it significantly increased fibrogenic gene expression and collagen accumulation in the liver. Increased liver fibrosis was accompanied by increased phosphorylation and nuclear localization of Smad3. Here, we demonstrate that HSD-fed mice develop a severe liver injury in the absence of KLF10 due to the hyperactivation of the endoplasmic reticulum stress response and CCAAT/enhance-binding protein homologous protein (CHOP)-mediated apoptosis of hepatocytes. The current study suggests that KLF10 plays a protective role against the progression of hepatic steatosis into liver fibrosis in a lipogenic state.

Casual alcohol consumption is associated with less subclinical cardiovascular organ damage in Koreans: a cross-sectional study.

BACKGROUND: Epidemiologic studies have presented protective effects of alcohol against cardiovascular (CV) events. However, such studies were performed mainly on Westerners. We investigated the effects of alcohol on the subclinical CV morbidity in healthy Koreans. METHODS: The coronary artery calcium (CAC) score, ankle-brachial pulse wave velocity (abPWV), and carotid intima-media thickness (cIMT) of 1004 subjects (age, years±standard deviation [SD] 53 ± 10; 72% were men) with no CV disease history were assessed. The subjects were divided into three groups based on their drinking patterns: Group 0 (abstainers), Group 1 (casual drinkers), and Group 2 (problematic drinkers; > 14 standard drinking/week for men, > 7 standard drinking/week for women). As drinking patterns can be influenced by age/sex, a regression analysis was performed in another four groups (men/women, age < 65/≥65 years). RESULTS: Group 1 exhibited lower CAC (score ± SD, 44 ± 155 vs. 13 ± 48 vs. 50 ± 159) and abPWV (cm/s ± SD, 1448 ± 284 vs. 1340 ± 190 vs. 1447 ± 245) scores and thinner cIMT (mm ± SD, 0.64 ± 0.14 vs. 0.59 ± 0.11 vs. 0.63 ± 0.13) than Groups 0 and 2 (p < 0.05 for all). Problematic drinking (odds ratio [OR]: 2.269; 95% confidence interval [CI]: 1.454-3.541) was associated with a high prevalence of CAC deposits among men aged < 65 years and casual drinking with a lower prevalence of CAC deposits (OR: 0.057; 95% CI: 0.023-0.140) among men aged ≥65 years. Conversely, problematic drinking in older women [OR: 0.117; 95% CI: 0.014-0.943) and casual drinking in younger women (OR: 0.349; 95% CI: 0.153-0.792) were associated with a lower prevalence of CAC deposits. Casual drinking was associated with a lower abPWV and thinner cIMT in the diabetes mellitus/hypertension-adjusted regression analysis. CONCLUSIONS: Compared with abstinence or problematic drinking, casual drinking was associated with less severe CV organ damage in the subclinical stages in Koreans.

ELOVL5 mutations cause spinocerebellar ataxia 38.

Spinocerebellar ataxias (SCAs) are a heterogeneous group of autosomal-dominant neurodegenerative disorders involving the cerebellum and 23 different genes. We mapped SCA38 to a 56 Mb region on chromosome 6p in a SCA-affected Italian family by whole-genome linkage analysis. Targeted resequencing identified a single missense mutation (c.689G>T [p.Gly230Val]) in ELOVL5. Mutation screening of 456 independent SCA-affected individuals identified the same mutation in two further unrelated Italian families. Haplotyping showed that at least two of the three families shared a common ancestor. One further missense variant (c.214C>G [p.Leu72Val]) was found in a French family. Both missense changes affect conserved amino acids, are predicted to be damaging by multiple bioinformatics tools, and were not identified in ethnically matched controls or within variant databases. ELOVL5 encodes an elongase involved in the synthesis of polyunsaturated fatty acids of the ω3 and ω6 series. Arachidonic acid and docosahexaenoic acid, two final products of the enzyme, were reduced in the serum of affected individuals. Immunohistochemistry on control mice and human brain demonstrated high levels in Purkinje cells. In transfection experiments, subcellular localization of altered ELOVL5 showed a perinuclear distribution with a signal increase in the Golgi compartment, whereas the wild-type showed a widespread signal in the endoplasmic reticulum. SCA38 and SCA34 are examples of SCAs due to mutations in elongase-encoding genes, emphasizing the importance of fatty-acid metabolism in neurological diseases.

Liver receptor homolog-1 regulates mouse superoxide dismutase 2.

Liver receptor homolog-1 (LRH-1) is a nuclear receptor that plays an important role in the regulation of bile acid biosynthesis, cholesterol reverse transport, steroidogenesis, and exocrine pancreatic enzyme production. In the current study, previously published data from a genome wide analysis of LRH-1 binding in the liver were re-analyzed to identify new LRH-1 targets and propose new roles for LRH-1 in the liver. Superoxide dismutase 2 (Sod2) was identified, which contains putative LRH-1 binding sites in the proximal promoter. When hepatocytes were treated with the LRH-1 agonist RJW101, Sod2 expression was dramatically increased and reactive oxygen species (ROS) production, which was induced by a high concentration of palmitate, was significantly reduced. A LRH-1 binding site was mapped to -288/-283 in the Sod2 promoter, which increased Sod2 promoter activity in response to LRH-1 and its agonist. LRH-1 binding to this site was confirmed using a chromatin immunoprecipitation assay. These results suggest that Sod2 is a target gene of LRH-1, and that LRH-1 agonists can mediate a reduction in ROS production and oxidative stress driven by an excess of fatty acids, as exhibited in nonalcoholic fatty liver disease.

Deletion of ELOVL6 blocks the synthesis of oleic acid but does not prevent the development of fatty liver or insulin resistance.

Elongation of very long chain fatty acid-like family member 6 (ELOVL6) is a fatty acyl elongase that performs the initial and rate-limiting condensing reaction required for microsomal elongation of long-chain fatty acids. Our previous in vitro studies suggested that ELOVL6 elongated long-chain saturated fatty acids and monounsaturated fatty acids with chain lengths of 12 to 16 carbons. Here, we describe the generation and phenotypic characterization of Elovl6(-/-) mice. As predicted from the in vitro studies, livers from Elovl6(-/-) mice accumulated palmitic (C16:0) and palmitoleic (C16:1, n-7) fatty acids and contained significantly less stearic (C18:0) and oleic (C18:1, n-9) acids, confirming that ELOVL6 is the only enzyme capable of elongating palmitate (C16:0). Unexpectedly, Elovl6(-/-) mice produced vaccenic acid (C18:1, n-7), the elongated product of palmitoleate (C16:1, n-7), suggesting that palmitoleate (C16:1, n-7) to vaccenate (C18:1, n-7) elongation was not specific to ELOVL6. The only detected consequence of deleting Elovl6(-/-) in mice was that their livers accumulated significantly more triglycerides than wild-type mice when fed a fat-free/high-carbohydrate diet. When mice were fed a high-fat diet or ELOVL6 was deleted in ob/ob mice, the absence of ELOVL6 did not alter the development of obesity, fatty liver, hyperglycemia, or hyperinsulinemia. Combined, these results suggest that palmitoleic (C16:1, n-7) and vaccenic (C18:1, n-7) acids can largely replace the roles of oleic acid (C18:1, n-9) in vivo and that the deletion of ELOVL6 does not protect mice from the development of hepatic steatosis or insulin resistance.

Reprogramming of tumor-associated macrophages by metabolites generated from tumor microenvironment.

The tumor microenvironment comprises both tumor and non-tumor stromal cells, including tumor-associated macrophages (TAMs), endothelial cells, and carcinoma-associated fibroblasts. TAMs, major components of non-tumor stromal cells, play a crucial role in creating an immunosuppressive environment by releasing cytokines, chemokines, growth factors, and immune checkpoint proteins that inhibit T cell activity. During tumors develop, cancer cells release various mediators, including chemokines and metabolites, that recruit monocytes to infiltrate tumor tissues and subsequently induce an M2-like phenotype and tumor-promoting properties. Metabolites are often overlooked as metabolic waste or detoxification products but may contribute to TAM polarization. Furthermore, macrophages display a high degree of plasticity among immune cells in the tumor microenvironment, enabling them to either inhibit or facilitate cancer progression. Therefore, TAM-targeting has emerged as a promising strategy in tumor immunotherapy. This review provides an overview of multiple representative metabolites involved in TAM phenotypes, focusing on their role in pro-tumoral polarization of M2.

Glucosamine increases macrophage lipid accumulation by regulating the mammalian target of rapamycin signaling pathway.

Elevated blood glucose is associated with an increased risk of atherosclerosis. Data from the current study showed that glucosamine (GlcN), a normal glucose metabolite of the hexosamine biosynthetic pathway (HBP), promoted lipid accumulation in RAW264.7 macrophage cells. Oleic acid- and lipopolysaccharide (LPS)-induced lipid accumulation was further enhanced by GlcN in RAW264.7 cells, although there was no a significant change in the rate of fatty acid uptake. GlcN increased acetyl CoA carboxylase (ACC), fatty acid synthase (FAS), scavenger receptor class A, liver X receptor, and sterol regulatory elementbinding protein-1c (SREBP-1c) mRNA expression, and; conversely, suppressed ATP-binding cassette transporter A1 (ABCA-1) and ABCG-1 expression. Additionally, GlcN promoted O-GlcNAcylation of nuclear SREBP-1 but did not affect its DNA binding activity. GlcN stimulated phosphorylation of mammalian target of rapamycin (mTOR) and S6 kinase. Rapamycin, a mTOR-specific inhibitor, suppressed GlcN-induced lipid accumulation in RAW264.7 cells. The GlcN-mediated increase in ACC and FAS mRNA was suppressed, while the decrease in ABCA-1 and ABCG-1 by GlcN was not significantly altered by rapamycin. Together, our results highlight the importance of the mTOR signaling pathway in GlcN-induced macrophage lipid accumulation and further support a potential link between mTOR and HBP signaling in lipogenesis. [BMB Reports 2024; 57(2): 92-97].

Effective RNAi-mediated gene silencing without interruption of the endogenous microRNA pathway.

Systemic administration of synthetic small interfering RNAs (siRNAs) effectively silences hepatocyte gene expression in rodents and primates. Whether or not in vivo gene silencing by synthetic siRNA can disrupt the endogenous microRNA (miRNA) pathway remains to be addressed. Here we show that effective target-gene silencing in the mouse and hamster liver can be achieved by systemic administration of synthetic siRNA without any demonstrable effect on miRNA levels or activity. Indeed, siRNA targeting two hepatocyte-specific genes (apolipoprotein B and factor VII) that achieved efficient (approximately 80%) silencing of messenger RNA transcripts and a third irrelevant siRNA control were administered to mice without significant changes in the levels of three hepatocyte-expressed miRNAs (miR-122, miR-16 and let-7a) or an effect on miRNA activity. Moreover, multiple administrations of an siRNA targeting the hepatocyte-expressed gene Scap in hamsters achieved long-term mRNA silencing without significant changes in miR-122 levels. This study advances the use of siRNAs as safe and effective tools to silence gene transcripts in animal studies, and supports the continued advancement of RNA interference therapeutics using synthetic siRNA.

Induced polymerization of mammalian acetyl-CoA carboxylase by MIG12 provides a tertiary level of regulation of fatty acid synthesis.

Acetyl-CoA carboxylase (ACC), the first committed enzyme in fatty acid (FA) synthesis, is regulated by phosphorylation/dephosphorylation, transcription, and an unusual mechanism of protein polymerization. Polymerization of ACC increases enzymatic activity and is induced in vitro by supraphysiological concentrations of citrate (> 5 mM). Here, we show that MIG12, a 22 kDa cytosolic protein of previously unknown function, binds to ACC and lowers the threshold for citrate activation into the physiological range (< 1 mM). In vitro, recombinant MIG12 induced polymerization of ACC (as determined by nondenaturing gels, FPLC, and electron microscopy) and increased ACC activity by > 50-fold in the presence of 1 mM citrate. In vivo, overexpression of MIG12 in liver induced ACC polymerization, increased FA synthesis, and produced triglyceride accumulation and fatty liver. Thus, in addition to its regulation by phosphorylation and transcription, ACC is regulated at a tertiary level by MIG12, which facilitates ACC polymerization and enhances enzymatic activity.

Crystal structure of Spot 14, a modulator of fatty acid synthesis.

Spot 14 (S14) is a protein that is abundantly expressed in lipogenic tissues and is regulated in a manner similar to other enzymes involved in fatty acid synthesis. Deletion of S14 in mice decreased lipid synthesis in lactating mammary tissue, but the mechanism of S14's action is unknown. Here we present the crystal structure of S14 to 2.65 Å and biochemical data showing that S14 can form heterodimers with MIG12. MIG12 modulates fatty acid synthesis by inducing the polymerization and activity of acetyl-CoA carboxylase, the first committed enzymatic reaction in the fatty acid synthesis pathway. Coexpression of S14 and MIG12 leads to heterodimers and reduced acetyl-CoA carboxylase polymerization and activity. The structure of S14 suggests a mechanism whereby heterodimer formation with MIG12 attenuates the ability of MIG12 to activate ACC.

Emerging roles of polyunsaturated fatty acid synthesis pathway in colorectal cancer.

The development of colorectal cancer typically involves the accumulated influences of genetic alterations, medical issues, lifestyle, and diet. Dietary fatty acids appear to affect the tumorigenesis and progression of colorectal cancer. Despite conflicting results, the current consensus on the effects of very long-chain polyunsaturated fatty acids on colorectal cancer is that low levels of eicosapentaenoic acid and docosahexaenoic acid, and high levels of arachidonic acid are associated with an increased risk of colorectal cancer. Altered levels of arachidonic acid in membrane phospholipids can change the levels of prostaglandin E2, which affect the biological activities of cancer cells in multiple stages. Arachidonic acid and other very long-chain polyunsaturated fatty acids can affect tumorigenesis in prostaglandin E2-independent manners as well, including stabilization of ß-catenine, ferroptosis, ROS generation, regulation of transcription factors, and de novo lipogenesis. Recent studies have revealed an association between the activities of enzymes synthesizing very long-chain polyunsaturated fatty acids and tumorigenesis and cancer progression, although the mechanisms are still unknown. In this study, PUFA effects on tumorigenesis, the endogenous very long-chain polyunsaturated fatty acid synthesis pathway, metabolites of arachidonic acid and their effects on tumorigenesis and progression of CRC, and current knowledge that supports the association of the enzymes involved in the polyunsaturated fatty acid synthesis pathway with colorectal cancer tumorigenesis and progression are reviewed.

Tumor-mediated 4-1BB induces tumor proliferation and metastasis in the colorectal cancer cells.

AIMS: 4-1BB is a member of the tumor necrosis factor receptor superfamily that mainly expressed on activated T-cells and plays important roles in cell proliferation and survival of T-cells and natural killer cells. The roles of 4-1BB in immune cells have been intensively studied, whereas little is known about the expression and roles of 4-1BB in cancer cells. MAIN METHODS: In the present study, we investigated 4-1BB expression in colorectal cancer tissues from human patients and established colorectal cancer cells, using mRNA expression, FACS, and immunostaining. Cancer cell proliferation and metastasis regulated by transfected 4-1BB was evaluated by cell growth rate, colony forming assay, cell migration, and Western blot with antibodies which are involved in epithelial-mesenchymal transition and anti-apoptosis. Expression of 4-1BB was knockdown by 4-1BB shRNA to prove that 4-1BB was involved in the cell proliferation. In vivo, 4-1BB transfected cancer cells were injected into mice, to induce tumor local region or lung. KEY FINDINGS: We found that colorectal cancer tissues from human patients and established colorectal cancer cells expressed 4-1BB at the high level. The higher expression of 4-1BB proliferated faster. In addition, we identified two forms of 4-1BB detected in colorectal cancer cells: full length form that was located on the plasma membrane and a short soluble form in the cytosol. The soluble form was also detected in the plasma from the mice with tumor xenografts expressed 4-1BB. SIGNIFICANCE: Tumor-mediated 4-1BB expression in the colorectal cancer cells showed effects on cancer cell proliferation, invasion, and metastasis.

Increased Hepatic Lipogenesis Elevates Liver Cholesterol Content.

Cardiovascular diseases (CVDs) are the most common cause of death in patients with nonalcoholic fatty liver disease (NAFLD) and dyslipidemia is considered at least partially responsible for the increased CVD risk in NAFLD patients. The aim of the present study is to understand how hepatic de novo lipogenesis influences hepatic cholesterol content as well as its effects on the plasma lipid levels. Hepatic lipogenesis was induced in mice by feeding a fat-free/high-sucrose (FF/HS) diet and the metabolic pathways associated with cholesterol were then analyzed. Both liver triglyceride and cholesterol contents were significantly increased in mice fed an FF/HS diet. Activation of fatty acid synthesis driven by the activation of sterol regulatory element binding protein (SREBP)-1c resulted in the increased liver triglycerides. The augmented cholesterol content in the liver could not be explained by an increased cholesterol synthesis, which was decreased by the FF/HS diet. HMGCoA reductase protein level was decreased in mice fed an FF/HS diet. We found that the liver retained more cholesterol through a reduced excretion of bile acids, a reduced fecal cholesterol excretion, and an increased cholesterol uptake from plasma lipoproteins. Very low-density lipoproteintriglyceride and -cholesterol secretion were increased in mice fed an FF/HS diet, which led to hypertriglyceridemia and hypercholesterolemia in Ldlr-/- mice, a model that exhibits a more human like lipoprotein profile. These findings suggest that dietary cholesterol intake and cholesterol synthesis rates cannot only explain the hypercholesterolemia associated with NAFLD, and that the control of fatty acid synthesis should be considered for the management of dyslipidemia.

Arachidonic acid induces ER stress and apoptosis in HT-29 human colon cancer cells.

Polyunsaturated fatty acids (PUFAs) have important functions in biological systems. The beneficial effects of dietary PUFAs against inflammatory diseases, cardiovascular diseases, and metabolic disorders have been shown. Studies using cancer cells have presented the anti-tumorigenic effects of docosahexaenoic acid (DHA), an n-3 PUFA, while arachidonic acid (AA), an n-6 PUFA, has been shown to elicit both pro- and anti-tumorigenic effects. In the current study, the anti-tumorigenic effects of AA were evaluated in HT-29 human colon cancer cells. Upon adding AA in the media, more than 90% of HT-29 cells died, while the MCF7 cells showed good proliferation. AA inhibited the expression of SREBP-1 and its target genes that encode enzymes involved in fatty acid synthesis. As HT-29 cells contained lower basal levels of fatty acid synthase, a target gene of SREBP-1, than that in MCF7 cells, the inhibitory effects of AA on the fatty acid synthase levels in HT-29 cells were much stronger than those in MCF-7 cells. When oleic acid (OA), a monounsaturated fatty acid that can be synthesized endogenously, was added along with AA, the HT-29 cells were able to proliferate. These results suggested that HT-29 cells could not synthesize enough fatty acids for cell division in the presence of AA because of the suppression of lipogenesis. HT-29 cells may incorporate more AA into their membrane phospholipids to proliferate, which resulted in ER stress, thereby inducing apoptosis. AA could be used as an anti-tumorigenic agent against cancer cells in which the basal fatty acid synthase levels are low.

Tumor-suppressing miR-141 gene complex-loaded tissue-adhesive glue for the locoregional treatment of hepatocellular carcinoma.

microRNAs (miRNAs) regulate gene expression post-transcriptionally and have been extensively tested as therapeutic molecules against several human diseases. In vivo delivery of miRNAs needs to satisfy the following conditions: safety, efficiency, and long-term therapeutic effectiveness. To satisfy these conditions, we developed a tissue-adhesive nucleotide-polymer complex (NPX-glue) for in vivo delivery of miRNAs to treat hepatocellular carcinoma (HCC). Methods: Polyallylamine (PAA), a cationic polymer, was mixed with tumor-suppressing miR-141 to form NPX and then mixed with partially oxidized alginate (OA) to form NPX-glue. Delivery efficiency of miR-141:NPX-glue was determined in cultured HCC cells and in an implanted HCC tumor model. In vivo tumor-suppressive effects of miR-141 on HCC were examined in mice upon intratumoral injection of miR-141:NPX-glue. Result: NPX-glue was generated by mixing of NPX with OA, which eliminated the inherent cytotoxic effect of NPX. NPX-glue led to the efficient delivery of miR-141 and plasmid to cultured cells and solid tumors in mice, where their expression was maintained for up to 30 days. Upon intratumoral injection of miR-141:NPX-glue, the growth of the tumors was dramatically retarded in comparison with the negative control, NCmiR:NPX-glue, (p < 0.05). Molecular examination proved miR-141:NPX-glue efficiently regulated the target genes including MAP4K4, TM4SF1, KEAP1, HDGF, and TIAM1 and finally induced apoptosis of cancer tissues. Conclusion: Here, we show that NPX-glue delivers therapeutic miR-141 to solid tumors in a safe, stable, and long-term manner and prove that locoregional treatment of HCC is possible using the NPX-glue system.

Truncated Adenomatous Polyposis Coli Mutation Induces Asef-Activated Golgi Fragmentation.

Adenomatous polyposis coli (APC) is a key molecule to maintain cellular homeostasis in colonic epithelium by regulating cell-cell adhesion, cell polarity, and cell migration through activating the APC-stimulated guanine nucleotide-exchange factor (Asef). The APC-activated Asef stimulates the small GTPase, which leads to decreased cell-cell adherence and cell polarity, and enhanced cell migration. In colorectal cancers, while truncated APC constitutively activates Asef and promotes cancer initiation and progression, regulation of Asef by full-length APC is still unclear. Here, we report the autoinhibition mechanism of full-length APC. We found that the armadillo repeats in full-length APC interact with the APC residues 1362 to 1540 (APC-2,3 repeats), and this interaction competes off and inhibits Asef. Deletion of APC-2,3 repeats permits Asef interactions leading to downstream signaling events, including the induction of Golgi fragmentation through the activation of the Asef-ROCK-MLC2. Truncated APC also disrupts protein trafficking and cholesterol homeostasis by inhibition of SREBP2 activity in a Golgi fragmentation-dependent manner. Our study thus uncovers the autoinhibition mechanism of full-length APC and a novel gain of function of truncated APC in regulating Golgi structure, as well as cholesterol homeostasis, which provides a potential target for pharmaceutical intervention against colon cancers.

The SCAP/SREBP Pathway: A Mediator of Hepatic Steatosis.

Nonalcoholic fatty liver disease (NAFLD) is strongly associated with insulin resistance, obesity, and dyslipidemia. NAFLD encompasses a wide range of states from the simple accumulation of triglycerides in the hepatocytes to serious states accompanied by inflammation and fibrosis in the liver. De novo lipogenesis has been shown to be a significant factor in the development of hepatic steatosis in insulin-resistant states. Sterol regulatory element binding protein-1c (SREBP-1c) is the main transcription factor that mediates the activation of lipogenesis, and SREBP cleavage activating protein (SCAP) is required for the activation of SREBPs. Here, recent animal studies that suggest SCAP as a therapeutic target for hepatic steatosis and hypertriglyceridemia are discussed.