TACE inhibition: a promising therapeutic intervention against AATF-mediated steatohepatitis to hepatocarcinogenesis

Metabolic dysfunction-associated steatohepatitis-driven hepatocellular carcinoma (MASH-HCC) is a global clinical challenge for which there is a limited understanding of disease pathogenesis and a subsequent lack of therapeutic interventions. We previously identified that tumor necrosis factor-alpha (TNF-α) upregulated apoptosis antagonizing transcription factor (AATF) in MASH. Here, we investigated the effect of TNF-α converting enzyme (TACE) inhibition as a promising targeted therapy against AATF-mediated steatohepatitis to hepatocarcinogenesis. A preclinical murine model that recapitulates human MASH-HCC was used in the study. C57Bl/6 mice were fed with chow diet normal water (CD) or western diet sugar water (WD) along with a low dose of carbon tetrachloride (CCl4; 0.2 μL·g-1, weekly) for 24 weeks. TACE activity, TNF-α levels, and AATF expression were measured. The mice were treated with the TACE inhibitor Marimastat for 12 weeks, followed by analyses of liver injury, fibrosis, inflammation, and oncogenic signaling. In vitro experiments using stable clones of AATF control and AATF knockdown were also conducted. We found that AATF expression was upregulated in WD/CCl4 mice, which developed severe MASH at 12 weeks and advanced fibrosis with HCC at 24 weeks. WD/CCl4 mice showed increased TACE activity with reduced hepatic expression of sirtuin 1 (Sirt1) and tissue inhibitor of metalloproteinase 3 (Timp3). The involvement of the SIRT1/TIMP3/TACE axis was confirmed by the release of TNF-α, which upregulated AATF, a key molecular driver of MASH-HCC. Interestingly, TACE inhibition by Marimastat reduced liver injury, dyslipidemia, AATF expression, and oncogenic signaling, effectively preventing hepatocarcinogenesis. Furthermore, Marimastat inhibited the activation of JNK, ERK1/2, and AKT, which are key regulators of tumorigenesis in WD/CCl4 mice and in AATF control cells, but had no effect on AATF knockdown cells. This study shows that TACE inhibition prevents AATF-mediated inflammation, fibrosis, and oncogenesis in MASH-HCC, offering a potential target for therapeutic intervention.

Apoptosis antagonizing transcription factor-mediated liver damage and inflammation to cancer: Therapeutic intervention by curcumin in experimental metabolic dysfunction associated steatohepatitis-hepatocellular carcinoma

In tandem with the expanding obesity pandemic, the prevalence of metabolic dysfunction associated steatohepatitis (MASH, formerly known as NASH)- driven hepatocellular carcinoma (HCC) is predicted to rise globally, creating a significant need for therapeutic interventions. We previously identified the upregulation of apoptosis antagonizing transcription factor (AATF), which is implicated in facilitating the progression from MASH to HCC. The objective of this study was to examine whether the intervention of curcumin could alleviate AATF-mediated MASH, inhibit tumor growth, and elucidate the underlying mechanism. A preclinical murine model mimicking human MASH-HCC was employed, subjecting mice to either a chow diet normal water (CDNW) or western diet sugar water (WDSW) along with very low dose of carbon tetrachloride (CCl4 - 0.2 μL/g, weekly). Mice receiving curcumin (CUR) alongside WDSW/CCl4 exhibited significant improvements, including reduced liver enzymes, dyslipidemia, steatosis, inflammation, and hepatocellular ballooning. Curcumin treatment also suppressed hepatic expression of inflammatory, fibrogenic, and oncogenic markers. Of note, there was a significant reduction in the expression of AATF upon curcumin treatment in WDSW/CCl4 mice and human HCC cells. In contrast, curcumin upregulated Kruppel-like factor 4 (KLF4) in MASH liver and HCC cells, which is known to downregulate sp1 (specificity protein-1) expression. Thus, curcumin treatment effectively inhibited the progression of MASH to HCC by downregulating the expression of AATF via the KLF4-Sp1 signaling pathway. These preclinical findings establish a novel molecular connection between curcumin and AATF in reducing hepatocarcinogenesis, and provide a strong rationale for the development of curcumin as a viable treatment for MASH-HCC in humans.

AATF inhibition exerts antiangiogenic effects against human hepatocellular carcinoma

Background and aims

Angiogenesis is a key factor in the growth and metastasis of hepatic tumors and thus a potential therapeutic target in hepatocellular carcinoma (HCC). In this study, we aim to identify the key role of apoptosis antagonizing transcription factor (AATF) in tumor angiogenesis and its underlying mechanisms in HCC.

Methods

HCC tissues were analyzed for AATF expression by qRT-PCR and immunohistochemistry. Stable clones of control and AATF knockdown (KD) were established in human HCC cells. The effect of AATF inhibition on the angiogenic processes was determined by proliferation, invasion, migration, chick chorioallantoic membrane (CAM) assay, zymography, and immunoblotting techniques.

Results

We identified high levels of AATF in human HCC tissues compared to adjacent normal liver tissues, and the expression was found to be correlated with the stages and tumor grades of HCC. Inhibiting AATF in QGY-7703 cells resulted in higher levels of pigment epithelium-derived factor (PEDF) than controls due to decreased matric metalloproteinase activity. Conditioned media from AATF KD cells inhibited the proliferation, migration, and invasion of human umbilical vein endothelial cells as well as the vascularization of the chick chorioallantoic membrane. Furthermore, the VEGF-mediated downstream signaling pathway responsible for endothelial cell survival and vascular permeability, cell proliferation, and migration favoring angiogenesis was suppressed by AATF inhibition. Notably, PEDF inhibition effectively reversed the anti-angiogenic effect of AATF KD.

Conclusion

Our study reports the first evidence that the therapeutic strategy based on the inhibition of AATF to disrupt tumor angiogenesis may serve as a promising approach for HCC treatment.

Quercetin activates vitamin D receptor and ameliorates breast cancer induced hepatic inflammation and fibrosis

Aims

To explore the hepatoprotective role of quercetin and its novel molecular mechanism of action on breast cancer associated hepatic inflammation and fibrosis via Vitamin D receptor (VDR).

Main methods

We used Ehrlich Ascites Carcinoma (mouse mammary carcinoma) model for our in-vivo experiments and human breast cancer cell lines for in-vitro assays. We inoculated 1.5 × 10⁶ Ehrlich ascites carcinoma cells into female Swiss albino mice. Quercetin (50 mg/kg) was administered intraperitoneally for 15 days. Liver enzymes activity was determined using a spectrophotometric assay. The hallmarks of inflammation and fibrosis were determined using Immunohistochemistry. The effect of quercetin on tumor formation was elucidated using human breast cancer cell lines and chick chorioallantoic membrane assay. Docking study was performed to explore the binding mode of quercetin with VDR.

Key findings

In EAC tumor-bearing mice, cell numbers, tumor volume, body weight and liver weight were dramatically increased, while they significantly decreased in mice treated with quercetin. Additionally, the peritoneal neo-angiogenesis was also significantly suppressed in the quercetin-treated mice, compared to the control. In addition, quercetin treated EAC tumor bearing mice had lower levels of liver enzymes, decreased hepatic inflammation and fibrosis compared with EAC tumor bearing mice. Docking study confirmed VDR-quercetin interaction. Furthermore, in-vitro assays and chick chorioallantoic membrane assay revealed the Vitamin D mimicking effect of quercetin.

Significance

Dietary flavonoid, quercetin could act as a promising therapeutic drug to suppress the breast cancer induced tumor angiogenesis, hepatic inflammation, and fibrosis possibly via activation of VDR.

The ameliorating effect of withaferin A on high-fat diet-induced non-alcoholic fatty liver disease by acting as an LXR/FXR dual receptor activator

Introduction: Non-alcoholic fatty liver disease (NAFLD) incidence has been rapidly increasing, and it has emerged as one of the major diseases of the modern world. NAFLD constitutes a simple fatty liver to chronic non-alcoholic steatohepatitis (NASH), which often leads to liver fibrosis or cirrhosis, a serious health condition with limited treatment options. Many a time, NAFLD progresses to fatal hepatocellular carcinoma (HCC). Nuclear receptors (NRs), such as liver X receptor-α (LXR-α) and closely associated farnesoid X receptor (FXR), are ligand-inducible transcription factors that regulate various metabolism-associated gene expressions and repression and play a major role in controlling the pathophysiology of the human liver. Withaferin A is a multifaceted and potent natural dietary compound with huge beneficial properties and plays a vital role as an anti-inflammatory molecule. Methods: In vivo: Swill albino mice were fed with western diet and sugar water (WDSW) for 12, 16, and 20 weeks with suitable controls. Post necropsy, liver enzymes (AST, ALT, and ALP) and lipid profile were measured by commercially available kits using a semi-auto analyzer in serum samples. Liver histology was assessed using H&E and MTS stains to check the inflammation and fibrosis, respectively, using paraffin-embedded sections and mRNA expressions of these markers were measured using qRT-PCR method. TGF-β1 levels in serum samples were quantified by ELISA. In vitro: Steatosis was induced in HepG2 and Huh7 cells using free fatty acids [Sodium Palmitate (SP) and Oleate (OA)]. After induction, the cells were treated with Withaferin A in dose-dependent manner (1, 2.5, and 5 μM, respectively). In vitro steatosis was confirmed by Oil-Red-O staining. Molecular Docking: Studies were conducted using Auto Dock Vina software to check the binding affinity of Withaferin-A to LXR-α and FXR. Results: We explored the dual receptor-activating nature of Withaferin A using docking studies, which potently improves high-fat diet-induced NAFLD in mice and suppresses diet-induced hepatic inflammation and liver fibrosis via LXR/FXR. Our in vitro studies also indicated that Withaferin A inhibits lipid droplet accumulation in sodium palmitate and oleate-treated HepG2 and Huh7 cells, which may occur through LXR-α and FXR-mediated signaling pathways. Withaferin A is a known inhibitor of NF-κB-mediated inflammation. Intriguingly, both LXR-α and FXR activation inhibits inflammation and fibrosis by negatively regulating NF-κB. Additionally, Withaferin A treatment significantly inhibited TGF-β-induced gene expression, which contributes to reduced hepatic fibrosis. Discussion: Thus, the LXR/ FXR dual receptor activator Withaferin A improves both NAFLD-associated liver inflammation and fibrosis in mouse models and under in vitro conditions, which makes Withaferin A a possibly potent pharmacological and therapeutic agent for the treatment of diet-induced NAFLD.

Vitamin D Target Genes in Dental Health

INTRODUCTION: Vitamin D is an important molecule which plays pivotal role in overall human health and metabolism. This vitamin acts as both vitamin as well as hormone, and thus, dual nature of this vitamin makes it as one of the important chemicals required for the overall health, harmonious growth, and development. Recently, this vitamin is gaining large attention in dentistry, and it is becoming master regulator of dental health. It is well studied that vitamin D plays major role in calcium absorption for bone and teeth mineralisation, it acts as odontogenic inducer of differentiation of human dental pulp cells and in tooth development. STUDY SELECTION, DATA, AND SOURCES: Vitamin D regulates various signalling pathways in dental network and plays a beneficial role. Synthesis of vitamin D takes place in multiple steps in human body. The natural form of vitamin D is fat soluble in nature and is produced in the skin from 7-dehydrocholesterol molecules. Natural Sunlight through its ultraviolet B (UVB) energy converts the precursor7-dehydrocholesterol molecules to vitamin D3. Advanced and unhealthy lifestyle of modern times has led to the deficiency of vitamin D and metabolic syndrome. CONCLUSIONS: Deficiency of vitamin D also leads to various dental problems including dental caries, gingivitis, and periodontal disease. In this short review, we are discussing the role of vitamin D and importance of its target genes in dental health. CLINICAL RELEVANCE: Vitamin D has a major role in managing the oral health this article updates the clinician with the different genes which are responsible for the regulation of vitamin D in different tissues.

Bacteria-Mediated Oncogenesis and the Underlying Molecular Intricacies: What We Know So Far

Cancers are known to have multifactorial etiology. Certain bacteria and viruses are proven carcinogens. Lately, there has been in-depth research investigating carcinogenic capabilities of some bacteria. Reports indicate that chronic inflammation and harmful bacterial metabolites to be strong promoters of neoplasticity. Helicobacter pylori-induced gastric adenocarcinoma is the best illustration of the chronic inflammation paradigm of oncogenesis. Chronic inflammation, which produces excessive reactive oxygen species (ROS) is hypothesized to cause cancerous cell proliferation. Other possible bacteria-dependent mechanisms and virulence factors have also been suspected of playing a vital role in the bacteria-induced-cancer(s). Numerous attempts have been made to explore and establish the possible relationship between the two. With the growing concerns on anti-microbial resistance and over-dependence of mankind on antibiotics to treat bacterial infections, it must be deemed critical to understand and identify carcinogenic bacteria, to establish their role in causing cancer.

Eventration of Diaphragm: A Rare Cadaveric Case Report

The respiratory diaphragm is a barrier between the thoracic and abdominal cavities. It is a chief skeletal muscle of respiration that plays a critical role in the process of inspiration. The defective diaphragm may be clinically present with or without obvious symptoms. Depending on the severity of its defects, it can lead to mild to severe fatal consequences. Protrusion of abdominal contents into the thoracic cavity through the weakened or defective part of the diaphragm is known as a diaphragmatic hernia. Such herniations will exist either in the form of congenital birth defects or acquired defects in the diaphragm. An acquired hernia may be due to spontaneous or iatrogenic causative factors. Congenital Diaphragmatic Hernia (CDH) can occur due to the disruption of various cellular mechanisms involved in organogenesis during the gestation period. Such herniations may exist with or without content protrusions into the cavity of the thorax, later referred to as Eventration of the Diaphragm (ED). In the Department of Anatomy at JSS Medical College, Mysuru, Karnataka, India, a rare case of diaphragmatic eventration was noticed in a male cadaver aged about 70 years, during the routine dissection class of preclinical medical students. In this rare case report, diaphragmatic eventration along with various factors involved in its presentation would be considered holistically

Extracellular Vesicles as Inflammatory Drivers in NAFLD

Non-alcoholic fatty liver disease (NAFLD) is a highly prevalent chronic liver disease in most parts of the world affecting one-third of the western population and a growing cause for end-stage liver diseases such as hepatocellular carcinoma (HCC). Majorly driven by obesity and diabetes mellitus, NAFLD is more of a multifactorial disease affected by extra-hepatic organ crosstalk. Non-alcoholic fatty liver (NAFL) progressed to non-alcoholic steatohepatitis (NASH) predisposes multiple complications such as fibrosis, cirrhosis, and HCC. Although the complete pathogenic mechanisms of this disease are not understood, inflammation is considered as a key driver to the onset of NASH. Lipotoxicity, inflammatory cytokines, chemokines, and intestinal dysbiosis trigger both hepatic and systemic inflammatory cascades simultaneously activating immune responses. Over a few years, extracellular vesicles studied extensively concerning the pathobiology of NAFLD indicated it as a key modulator in the setting of immune-mediated inflammation. Exosomes and microvesicles, the two main types of extracellular vesicles are secreted by an array of most mammalian cells, which are involved mainly in cell-cell communication that are unique to cell type. Various bioactive cargoes containing extracellular vesicles derived from both hepatic and extrahepatic milieu showed critical implications in driving steatosis to NASH reaffirming inflammation as the primary contributor to the whole process. In this mini-review, we provide brief insights into the inflammatory mediators of NASH with special emphasis on extracellular vesicles that acts as drivers of inflammation in NAFLD.

Withaferin A Acts as a Novel Regulator of Liver X Receptor-α in HCC

Withaferin A, a steroidal lactone derived from the Withania somnifera plant has been known for its anti-cancerous effects on various types of cancer cells. However, its effect on the hallmarks of cancer such as proliferation, migration, invasion, and angiogenesis is still poorly understood. The antitumor property of Withaferin A and its molecular mechanism of action on hepatocellular carcinoma (HCC) cells is not yet completely established. In this study, we aimed to elucidate the novel molecular function of Withaferin A on HCC cells and its effect on various gene expression. Our results clearly showed that Withaferin A treatment to HCC cells inhibited proliferation, migration, invasion, and anchorage-independent growth. Further, we explored the Withaferin A target genes by blotting human angiogenesis, and cytokine arrays using conditioned media of Withaferin A treated QGY-7703 cells. We found that many of Nuclear factor kappa B (NF-κB), angiogenesis and inflammation associated proteins secretion is downregulated upon Withaferin A treatment. Interestingly, all these genes expression is also negatively regulated by nuclear receptor Liver X receptor-α (LXR-α). Here, we explored a novel mechanism that Withaferin-A activated LXR-α inhibits NF-κB transcriptional activity and suppressed the proliferation, migration, invasion, and anchorage-independent growth of these HCC cells. All these data strongly confirmed that Withaferin A is a potent anticancer compound and suppresses various angiogenesis and inflammatory markers which are associated with the development and progression of HCC. This beneficial and potential therapeutic property of Withaferin A will be very useful for the treatment of HCC.

COVID-19 and gastrointestinal system: A brief review

COVID-19 is a recent pandemic that is still a major health problem of modern times and already more than 17.5 lakhs people succumbed to this deadly disease. This disease is caused by novel coronavirus which is named SARS-COV-2 by the International Committee on Taxonomy of Viruses. This virus originated from Wuhan city in Hubei province of China in December 2019 and within a short period spread across the many countries in the globe. There are a lot of basic as well as clinical research is going on to study the mode of transmission and the mechanism of action of SARS-COV-2 infection and its therapeutics. SARS-COV-2 is not only known to infect lungs, but it also infects other organs in the human body including the gastrointestinal (GI) tract, the liver, and the pancreas via the angiotensin-converting enzyme (ACE) 2, an important component of the renin-angiotensin system. In this short review, we are mainly discussing the mode of SARS-COV-2 transmission, physiological counterbalancing roles of ACE2 and ACE and the tissue patterns of ACE2 expression, and the overall effect of COVID19 on human gastrointestinal System. Therefore, this review sheds light on the possible mechanism of SARS-COV-2 infection in the GI system and its pathological symptoms raising a potential possibility of GI tract acting as a secondary site for SARS-CoV-2 tropism and infection. Finally, future studies to understand the fecal-oral transmission of the virus and the correlation of viral load and severity of GI symptoms are proposed to gain knowledge of the GI symptoms in COVID-19 to aid in early diagnosis and prognosis.

Emerging roles of AATF: Checkpoint signaling and beyond

Apoptosis antagonizing transcription factor (AATF), an interacting partner of RNA polymerase II is a multifunctional protein that is highly conserved in eukaryotes. In addition to the regulation of gene expression as a transcriptional coactivator, AATF is shown to play a dual role in regulating the cell cycle by displacing histone deacetylases 1 (HDAC1) from the retinoblastoma-E2F transcription factor (Rb-E2F) complex and also from the specificity protein 1 (Sp1) transcription factor responsible for p21 expression, thereby ensuring cell proliferation and growth arrest, respectively, at different checkpoints of the cell cycle. Notably, AATF has emerged as one of the most important modulators of various cellular responses such as proliferation, apoptosis, and survival. Studies have demonstrated that AATF protects cells from multiple stress stimuli such as DNA damage, ER stress, hypoxia, or glucose deprivation by inducing cell cycle arrest, autophagy, or apoptosis inhibition. Furthermore, AATF serves as a critical regulator in various cancers and promotes tumorigenesis by protecting cancer cells from apoptosis induction, favoring cell proliferation, or promoting cell survival by autophagy. Recent studies have demonstrated the key role of AATF in ribosome biosynthesis and have also provided insights into the mechanistic role of AATF, offering impressive cytoprotection in myocardial infarction, neurologic diseases, and nephronophthisis. In this review, we will provide a comprehensive overview of the role of AATF and shed light on its emerging roles underlining the potential use of AATF as a novel biomarker and as an effective therapeutic target.

Identification of a Metabolic, Transcriptomic, and Molecular Signature of Patatin-Like Phospholipase Domain Containing 3-Mediated Acceleration of Steatohepatitis

BACKGROUND AND AIMS

The mechanisms by which the I148M mutant variant of the patatin-like phospholipase domain-containing 3 (PNPLA3^I148M ) drives development of nonalcoholic steatohepatitis (NASH) are not known. The aim of this study was to obtain insights on mechanisms underlying PNPLA3^I148M -induced acceleration of NASH.

APPROACH AND RESULTS

Hepatocyte-specific overexpression of empty vector (luciferase), human wild-type PNPLA3, or PNPLA3^I148M was achieved using adeno-associated virus 8 in a diet-induced mouse model of nonalcoholic fatty liver disease followed by chow diet or high-fat Western diet with ad libitum administration of sugar in drinking water (WDSW) for 8 weeks. Under WDSW, PNPLA3^I148M overexpression accelerated steatohepatitis with increased steatosis, inflammation ballooning, and fibrosis (P < 0.001 versus other groups for all). Silencing PNPLA3^I148M after its initial overexpression abrogated these findings. PNPLA3^I148M caused 22:6n3 docosahexanoic acid depletion and increased ceramides under WDSW in addition to increasing triglycerides and diglycerides, especially enriched with unsaturated fatty acids. It also increased oxidative stress and endoplasmic reticulum stress. Increased total ceramides was associated with signature of transducer and activator of transcription 3 (STAT3) activation with downstream activation of multiple immune-inflammatory pathways at a transcriptomic level by network analyses. Silencing PNPLA3^I148M reversed STAT3 activation. Conditioned media from HepG2 cells overexpressing PNPLA3^I148M increased procollagen mRNA expression in LX2 cells; this was abrogated by hepatocyte STAT3 inhibition.

CONCLUSIONS

Under WDSW, PNPLA3^I148M overexpression promotes steatosis and NASH by metabolic reprogramming characterized by increased triglycerides and diglycerides, n3 polyunsaturated fatty acid depletion, and increased ceramides with resultant STAT3 phosphorylation and downstream inflammatory pathway activation driving increased stellate cell fibrogenic activity.

RISC assembly and post-transcriptional gene regulation in Hepatocellular Carcinoma

RNA-induced silencing complex (RISC) is one of the basic eukaryotic cellular machinery which plays a pivotal role in post-transcriptional gene regulation. Discovery of miRNAs and their role in gene regulation have changed the course of modern biology. The method of gene silencing using small interfering RNAs and miRNAs has become major tool in molecular biology and genetic engineering. Hepatocellular Carcinoma (HCC) is a very common malignancy of liver in developing countries and due to various risk factors; the prevalence of this disease is rapidly increasing throughout the globe. There exists an imbalance in interplay between oncogenes and tumor suppressor genes and their regulation plays a major role in HCC growth, development and metastasis. The regulatory function of RISC and miRNAs make them a very important mediators of cancer signaling in HCC. Therefore, targeting the RISC complex for HCC therapy is the need of the time.

The dark face of fructose as a tumor promoter

Fructose, an essential biomolecule and it is a major ingredient of the modern diet across the globe. Excess consumption of fructose may be a key driver of many serious diseases such as obesity, heart diseases, type 2 diabetes and cancer. Understanding the metabolism of fructose, molecular mechanisms of its toxic nature will aid in the treatment of various diseases including cancer.

A Regulatory Role of Apoptosis Antagonizing Transcription Factor in the Pathogenesis of Nonalcoholic Fatty Liver Disease and Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is increasing as a cause of liver-related mortality largely because of the growing burden of nonalcoholic steatohepatitis (NASH). The mechanisms of HCC development in nonalcoholic fatty liver disease (NAFLD) are incompletely understood. We initially identified apoptosis antagonizing transcription factor (AATF) to be associated with HCC in a mouse model of NASH that develops HCC without the addition of specific carcinogens. AATF, also called che-1, is a transcriptional factor that is highly conserved among eukaryotes. AATF is known to be a central mediator of the cellular responses as it promotes cell proliferation and survival by inducing cell cycle arrest, autophagy, DNA repair, and inhibition of apoptosis. However, the role of AATF in NASH and HCC remains unknown. Here, we provide evidence for AATF as a contributory factor for HCC in NAFLD. AATF overexpression was further verified in human NASH and HCC and multiple human HCC cell lines. Tumor necrosis factor-α (TNFα), known to be increased in NASH, induced AATF expression. Promoter analysis of AATF revealed a sterol regulatory element binding transcription factor 1-c (SREBP-1c) binding site; inhibition of SREBP-1 by using specific inhibitors as well as small interfering RNA decreased TNFα-induced AATF expression. AATF interacted with signal transducer and activator of transcription 3 to increase monocyte chemoattractant protein-1 expression. AATF knockdown decreased cell proliferation, migration, invasion, colony formation, and anchorage-dependent growth in HCC cell lines. Xenograft of QGY-7703 HCC cells with AATF stably knocked down into nonobese diabetic scid gamma mice demonstrated reduced tumorigenesis and metastases. Conclusion: AATF drives NAFLD and hepatocarcinogenesis, offering a potential target for therapeutic intervention.

The presence and severity of nonalcoholic steatohepatitis is associated with specific changes in circulating bile acids

The histologic spectrum of nonalcoholic fatty liver disease (NAFLD) includes fatty liver (NAFL) and steatohepatitis (NASH), which can progress to cirrhosis in up to 20% of NASH patients. Bile acids (BA) are linked to the pathogenesis and therapy of NASH. We (1) characterized the plasma BA profile in biopsy-proven NAFL and NASH and compared to controls and (2) related the plasma BA profile to liver histologic features, disease activity, and fibrosis. Liquid chromatography/mass spectrometry quantified BAs. Descriptive statistics, paired and multiple group comparisons, and regression analyses were performed. Of 86 patients (24 controls, 25 NAFL, and 37 NASH; mean age 51.8 years and body mass index 31.9 kg/m² ), 66% were women. Increased total primary BAs and decreased secondary BAs (both P < 0.05) characterized NASH. Total conjugated primary BAs were significantly higher in NASH versus NAFL (P = 0.047) and versus controls (P < 0.0001). NASH had higher conjugated to unconjugated chenodeoxycholate (P = 0.04), cholate (P = 0.0004), and total primary BAs (P < 0.0001). The total cholate to chenodeoxycholate ratio was significantly higher in NAFLD without (P = 0.005) and with (P = 0.02) diabetes. Increased key BAs were associated with higher grades of steatosis (taurocholate), lobular (glycocholate) and portal inflammation (taurolithocholate), and hepatocyte ballooning (taurocholate). Conjugated cholate and taurocholate directly and secondary to primary BA ratio inversely correlated to NAFLD activity score. A higher ratio of total secondary to primary BA decreased (odds ratio, 0.57; P = 0.004) and higher conjugated cholate increased the likelihood of significant fibrosis (F≥2) (P = 0.007). Conclusion: NAFLD is associated with significantly altered circulating BA composition, likely unaffected by type 2 diabetes, and correlated with histological features of NASH; these observations provide the foundation for future hypothesis-driven studies of specific effects of BAs on specific aspects of NASH. (Hepatology 2018;67:534-548).

Preclinical models of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) can manifest as non-alcoholic fatty liver (NAFL) or non-alcoholic steatohepatitis (NASH). NASH is often associated with progressive fibrosis which can lead to cirrhosis and hepatocellular carcinoma (HCC). NASH is increasing as an aetiology for end-stage liver disease as well as HCC. There are currently no approved therapies for NASH. A major barrier to development of therapeutics for NASH is the lack of preclinical models of disease that are appropriately validated to represent the biology and outcomes of human disease. Many in vitro and animal models have been developed. In vitro models do not fully capture the hepatic and extrahepatic milieu of human NASH and large animal models are expensive and logistically difficult to use. Therefore, there is considerable interest in the development and validation of mouse models for NAFLD, including NASH. Several models based on varying genetic or dietary manipulations have been developed. However, the majority do not recreate steatohepatitis, strictly defined as the presence of hepatocellular ballooning with or without Mallory-Denk bodies, accompanied by inflammation in the presence of macrovesicular steatosis. Others lack validation against human disease. Herein, we describe the best practices in development of mouse models of NASH. We further review existing models and the literature supporting their use as a surrogate for human disease. Finally, data on models to evaluate protective genes are discussed. It is hoped that this review will provide guidance for the interpretation of data derived from mouse models and also for the development and validation of newer models.

Fast and Simplified Method for High Through-put Isolation of miRNA from Highly Purified High Density Lipoprotein

Small non-coding RNAs (miRNAs) have been implicated in a variety of human diseases including metabolic syndromes. They may be utilized as biomarkers for diagnosis and prognosis or may serve as targets for drug development, respectively. Recently it has been shown that miRNAs are carried in lipoproteins, particularly high density lipoproteins (HDL) and are delivered to recipient cells for uptake. This raises the possibility that miRNAs play a critical and pivotal role in cellular and organ function via regulation of gene expression as well as messenger for cell-cell communications and crosstalk between organs. Current methods for miRNA isolation from purified HDL are impractical when utilizing small samples on a large scale. This is largely due to the time consuming and laborious methods used for lipoprotein isolation. We have developed a simplified approach to rapidly isolate purified HDL suitable for miRNA analysis from plasma samples. This method should facilitate investigations into the role of miRNAs in health and disease and in particular provide new insights into the variety of biological functions, outside of the reverse cholesterol transport, that have been ascribed to HDL. Also, the miRNA species which are present in HDL can provide valuable information of clinical biomarkers for diagnosis of various diseases.

Tetraspanin 8 mediates AEG-1-induced invasion and metastasis in hepatocellular carcinoma cells

Astrocyte-elevated gene-1 (AEG-1) positively regulates tumor progression and metastasis. Here, we document that AEG-1 upregulates transcription of the membrane protein tetraspanin 8 (TSPAN8). Knocking down TSPAN8 in AEG-1-overexpressing human hepatocellular carcinoma (HCC) cells markedly inhibited invasion and migration without affecting proliferation. TSPAN8 knockdown profoundly abrogated AEG-1-induced primary tumor and intrahepatic metastasis in an orthopic xenograft model in athymic nude mice. Coculture of TSPAN8 knockdown cells with human umbilical vein endothelial cells (HUVEC) markedly inhibited HUVEC tube formation indicating that inhibition of angiogenesis might cause reduction in primary tumor size. TSPAN8 inhibition might be a potential therapeutic strategy for metastatic HCC.

Suppression of miR-184 in malignant gliomas upregulates SND1 and promotes tumor aggressiveness

BACKGROUND

Malignant glioma is an aggressive cancer requiring new therapeutic targets. MicroRNAs (miRNAs) regulate gene expression post transcriptionally and are implicated in cancer development and progression. Deregulated expressions of several miRNAs, specifically hsa-miR-184, correlate with glioma development.

METHODS

Bioinformatic approaches were used to identify potential miR-184-regulated target genes involved in malignant glioma progression. This strategy identified a multifunctional nuclease, SND1, known to be overexpressed in multiple cancers, including breast, colon, and hepatocellular carcinoma, as a putative direct miR-184 target gene. SND1 levels were evaluated in patient tumor samples and human-derived cell lines. We analyzed invasion and signaling in vitro through SND1 gain-of-function and loss-of-function. An orthotopic xenograft model with primary glioma cells demonstrated a role of miR-184/SND1 in glioma pathogenesis in vivo.

RESULTS

SND1 is highly expressed in human glioma tissue and inversely correlated with miR-184 expression. Transfection of glioma cells with a miR-184 mimic inhibited invasion, suppressed colony formation, and reduced anchorage-independent growth in soft agar. Similar phenotypes were evident when SND1 was knocked down with siRNA. Additionally, knockdown (KD) of SND1 induced senescence and improved the chemoresistant properties of malignant glioma cells. In an orthotopic xenograft model, KD of SND1 or transfection with a miR-184 mimic induced a less invasive tumor phenotype and significantly improved survival of tumor bearing mice.

CONCLUSIONS

Our study is the first to show a novel regulatory role of SND1, a direct target of miR-184, in glioma progression, suggesting that the miR-184/SND1 axis may be a useful diagnostic and therapeutic tool for malignant glioma.

Staphylococcal nuclease domain containing-1 (SND1) promotes migration and invasion via angiotensin II type 1 receptor (AT1R) and TGFβ signaling

Staphylococcal nuclease domain containing-1 (SND1) is overexpressed in human hepatocellular carcinoma (HCC) patients and promotes tumorigenesis by human HCC cells. We now document that SND1 increases angiotensin II type 1 receptor (AT1R) levels by increasing AT1R mRNA stability. This results in activation of ERK, Smad2 and subsequently the TGFβ signaling pathway, promoting epithelial-mesenchymal transition (EMT) and migration and invasion by human HCC cells. A positive correlation was observed between SND1 and AT1R expression levels in human HCC patients. Small molecule inhibitors of SND1, alone or in combination with AT1R blockers, might be an effective therapeutic strategy for late-stage aggressive HCC.

Targeted apoptotic effects of thymoquinone and tamoxifen on XIAP mediated Akt regulation in breast cancer

X-linked inhibitor of apoptosis protein (XIAP) is constitutively expressed endogenous inhibitor of apoptosis, exhibit its antiapoptotic effect by inactivating key caspases such as caspase-3, caspase-7 and caspase-9 and also play pivotal role in rendering cancer chemoresistance. Our studies showed the coadministration of TQ and TAM resulting in a substantial increase in breast cancer cell apoptosis and marked inhibition of cell growth both in vitro and in vivo. Anti-angiogenic and anti-invasive potential of TQ and TAM was assessed through in vitro studies. This novel combinatorial regimen leads to regulation of multiple cell signaling targets including inactivation of Akt and XIAP degradation. At molecular level, TQ and TAM synergistically lowers XIAP expression resulting in binding and activation of caspase-9 in apoptotic cascade, and interfere with cell survival through PI3-K/Akt pathway by inhibiting Akt phosphorylation. Cleaved caspase-9 further processes other intracellular death substrates such as PARP thereby shifting the balance from survival to apoptosis, indicated by rise in the sub-G₁ cell population. This combination also downregulates the expression of Akt-regulated downstream effectors such as Bcl-xL, Bcl-2 and induce expression of Bax, AIF, cytochrome C and p-27. Consistent with these results, overexpression studies further confirmed the involvement of XIAP and its regulatory action on Akt phosphorylation along with procaspase-9 and PARP cleavage in TQ-TAM coadministrated induced apoptosis. The ability of TQ and TAM in inhibiting XIAP was confirmed through siRNA-XIAP cotransfection studies. This novel modality may be a promising tool in breast cancer treatment.

Abstract 5437: Astrocyte Elevated Gene-1 (AEG-1) interacts with retinoid X receptor (RXR) and abrogates its function

The oncogene Astrocyte Elevated Gene-1 (AEG-1), also known as Metadherin (MTDH), is overexpressed in a diverse array of cancers, including hepatocellular carcinoma (HCC), and plays an important role in promoting tumor development and progression. Protein-protein interaction predominantly mediates the tumor promoting effects of AEG-1. We now describe screening of a human liver cDNA library by yeast two hybrid assay resulting in identification of Retinoid X Receptor (RXR) as an AEG-1-interacting protein. Site-directed mutagenesis assays identified an LXXLL motif in the N-terminus of AEG-1 mediating interaction with RXR. We employed human HCC cell lines stably overexpressing AEG-1 or with knockdown of AEG-1 and mouse hepatocytes isolated from a transgenic mouse with hepatocyte-specific expression of AEG-1 (Alb/AEG-1) and from AEG-1 knockout (AEG-1 KO) mouse for our studies. Luciferase reporter assays in these cells demonstrate that AEG-1 profoundly inhibits RXR-mediated transcriptional regulation of its heterodimer partner, such as Retinoic Acid Receptor (RAR), Thyroid Hormone Receptor (TR), Liver X Receptor (LXR) and Peroxisome Proliferator-Activated Receptor (PPAR), in the presence or absence of their corresponding ligands. In this study, we focus on retinoic acid (RA) and thyroid hormone (T3) function. AEG-1 markedly inhibits expression of RA- and T3-induced genes. Overexpressed AEG-1 in cancer cells and in transgenic hepatocytes accumulates in the cytoplasm and inhibits RXR function by trapping RXR in the cytoplasm precluding its nuclear translocation. Additionally, AEG-1 induces phosphorylation of RXR, via ERK and p38 MAPK pathways. Phosphorylated RXR has low transcriptional activity, functions as dominant negative inhibitor of RXR and might facilitate hepatocarcinogenesis by AEG-1. Indeed, chromatin immunoprecipitation (ChIP) assay using RA-target genes, RARB and HOXA1, shows decreased DNA binding of RXR, even upon ligand-treatment. Overexpression of AEG-1 significantly protects human HCC cells, mouse hepatocytes and human promyelocytic leukemia cells from the killing effects of retinoic acid and its synthetic analogs. By inhibiting the expression of T3-regulated gene type I deiodinase (DIO1), AEG-1 abrogates peripheral conversion of inactive T4 to active T3 which is reflected by significantly low T3 level in the circulation of Alb/AEG-1 mice compared to WT mice. Since AEG-1 is upregulated in a wide-variety of cancers it might play an important role in regulating a diverse array of RXR-dependent signaling pathways that are critical for regulating the oncogenic process. Synthetic retinoids are being evaluated as chemopreventive agents for HCC as well as a therapeutic modality for PML. AEG-1 expression level might determine the sensitivity of the patients to these retinoids. Additionally AEG-1 might play a key role in ‘low T3 syndrome’ associated with cancer.

Citation Format: Jyoti Srivastava, Chadia L. Robertson, Rachel Gredler, Ayesha Siddiq, Devaraja Rajasekaran, Prasanna K. Santhekadur, Paul B. Fisher, Devanand Sarkar. Astrocyte Elevated Gene-1 (AEG-1) interacts with retinoid X receptor (RXR) and abrogates its function. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5437. doi:10.1158/1538-7445.AM2013-5437

Abstract 2628: The multifunctional protein staphylococcal nuclease domain containing-1 (SND1) promotes migration and invasion of hepatocellular carcinoma (HCC) cells by modulating angiotensin II type 1 receptor (AT1R) and transforming growth factor-β (TGF-β) s

Staphylococcal nuclease domain containing-1 (SND1) is a multifunctional protein that modulates transcription, mRNA splicing and stability, and miRNA function. We previously documented that SND1 is markedly overexpressed in human hepatocellular carcinoma (HCC) patients in a stage-specific manner and inhibition of SND1 in human HCC cells significantly abrogates in vitro proliferation and in vivo tumorigenesis in nude mice. In the present study we document that migration and invasion of human HCC cells are significantly augmented in SND1-overexpressing clones and significantly inhibited in SND1 shRNA-expressing clones. Differential gene expression analysis between control clone and SND1 shRNA expressing clones by Affymetrix microarray revealed downregulation of TGF-β downstream genes upon SND1 inhibition. Additionally, a human angiogenesis array identified plasminogen activator inhibitor-1 (PAI-1), a TGF-β downstream gene, to be upregulated by SND1 and this upregulation was confirmed by ELISA. TGF-β expression is regulated by angiotensin II type 1 receptors (AT1R) and previous studies have documented that SND1 increases AT1R expression by increasing AT1R mRNA stability. We hypothesized that increased AT1R expression, conferred by SND1 overexpression, might facilitate activation of TGF-β signaling and subsequently PAI-1-mediated increase in migration and invasion. Indeed, we observed that AT1R and TGF-β expression was significantly increased in SND1-overexpressing clones and decreased in SND1 knockdown clones. The half-life of AT1R mRNA was significantly longer in SND1-overexpressing clones compared to the control clone confirming that SND1 modulates AT1R post-transcriptionally. The AT1R blocker Losartan Potassium and AT1R siRNA significantly inhibited SND1-induced TGF-β and PAI-1 expression with associated inhibition in migration and invasion. As a corollary, inhibition of PAI-1 by siRNA significantly abrogated migration and invasion of SND1-overexpressing cells. TGF-β induces epithelial-mesenchymal transition (EMT) and we observed increased expression of EMT markers vimentin, snail and slug and decreased expression of E-cadherin in SND1-overexpressing clones and vice versa in SND1-knockdown clones. Our studies thus unravel a novel mechanism in which post-transcriptional regulation of AT1R by SND1, with subsequent activation of TGF-β signaling, promotes invasion of human HCC cells thereby conferring an aggressive phenotype. Small molecule inhibitors of SND1, thus, might be effective therapeutic strategy for late-stage aggressive HCC.

Citation Format: Prasanna K. Santhekadur, Rachel Gredler, Maaged Akiel, Paul Dent, Paul B. Fisher, Devanand Sarkar. The multifunctional protein staphylococcal nuclease domain containing-1 (SND1) promotes migration and invasion of hepatocellular carcinoma (HCC) cells by modulating angiotensin II type 1 receptor (AT1R) and transforming growth factor-β (TGF-β) s [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2628. doi:10.1158/1538-7445.AM2013-2628

Abstract 3902: MDA-9/syntenin and IGFBP-2 promote angiogenesis in human melanoma

Vascularization of tumors promotes not only their survival and growth, but also facilitates metastases from primary to distant sites. For that reason, understanding the molecular determinants controlling tumor angiogenesis is mandatory to develop clinically efficacious angiogenesis inhibitors for cancer therapy. Melanoma differentiation associated gene or mda-9, also known as syntenin, is a multifunctional scaffold protein that cross talks with a plethora of proteins and regulates diverse physiological and pathological processes, including tumor progression and metastasis. Since, tumor angiogenesis promotes metastasis, we hypothesized that in addition to augmenting invasion and migration, MDA-9/Syntenin might also promote angiogenesis thereby facilitating tumor progression and metastasis.

Genetic (gain-of-function and loss-of-function) and pharmacological approaches were employed to modify mda-9/syntenin expression in normal immortal melanocytes, early radial growth phase melanoma and metastatic melanoma cells. The consequence of modifying mda-9/syntenin expression on angiogenesis was evaluated using both in vitro and in vivo assays, including tube formation assays using human vascular endothelial cells, chicken choriallantoic membrane assays (CAM assays) and xenograft tumor animal models.

Employing both genetic and chemical approaches we now demonstrate that MDA-9/Syntenin expression correlates with in vitro and in vivo (tumorigenic/metastatic) transformed/invasive phenotypes of human melanoma. Additionally, our immunohistochemical and in vivo CAM assays confirm that angiogenesis is an essential component of MDA-9/Syntenin-induced tumor progression. To define how MDA-9/Syntenin regulates angiogenesis we identified and analyzed several potential downstream gene targets of MDA-9/Syntenin. One gene implicated in induction of vasculogenesis is insulin growth factor binding protein-2 (IGFBP-2), which is transcriptionally regulated by hypoxia inducible factor-1 as a consequence of MDA-9/Syntenin and Src interaction. IGFBP-2 transcriptionally regulates VEGF-A in an AKT-dependent manner through interaction with V3 integrin resulting in angiogenesis.

Our studies delineate an unanticipated cell non-autonomous function of MDA-9/Syntenin in the context of angiogenesis by augmenting expression of several pro-angiogenic factors including IGFBP-2, which may provide a complementary way to promote metastasis. As a result, targeting MDA-9/syntenin or its downstream-regulated molecules may provide a means of simultaneously impeding metastasis by both directly inhibiting tumor cell transformed properties (autonomous) and indirectly by blocking angiogenesis (non-autonomous).

Citation Format: Swadesh K. Das, Timothy P. Kegelman, Prasanna K. Santhekadur, Santanu Dasgupta, Paul Dent, Steven Grant, Luni Emdad, Devanand Sarkar, Paul B. Fisher, Maurizio Pellecchia. MDA-9/syntenin and IGFBP-2 promote angiogenesis in human melanoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3902. doi:10.1158/1538-7445.AM2013-3902

RETRACTED: Insulin-like growth factor-binding protein-7 (IGFBP7): a promising gene therapeutic for hepatocellular carcinoma (HCC)

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the editor-in-chief. Similarities were found between images within this article. Image analysis performed by the editorial office confirmed findings of image duplication in Figures 1B, 4, and 8A. This reuse (and in part misrepresentation) of data without appropriate attribution represents a severe abuse of the scientific publishing system. No authors responded when contacted about the retraction.

MDA-9/syntenin and IGFBP-2 promote angiogenesis in human melanoma

Melanoma differentiation-associated gene-9 (mda-9/syntenin) encodes an adapter scaffold protein whose expression correlates with and mediates melanoma progression and metastasis. Tumor angiogenesis represents an integral component of cancer metastasis prompting us to investigate a possible role of mda-9/syntenin in inducing angiogenesis. Genetic (gain-of-function and loss-of-function) and pharmacologic approaches were used to modify mda-9/syntenin expression in normal immortal melanocytes, early radial growth phase melanoma, and metastatic melanoma cells. The consequence of modifying mda-9/syntenin expression on angiogenesis was evaluated using both in vitro and in vivo assays, including tube formation assays using human vascular endothelial cells, chorioallantoic membrane (CAM) assays and xenograft tumor animal models. Gain-of-function and loss-of-function experiments confirm that MDA-9/syntenin induces angiogenesis by augmenting expression of several proangiogenic factors/genes. Experimental evidence is provided for a model of angiogenesis induction by MDA-9/syntenin in which MDA-9/syntenin interacts with the extracellular matrix (ECM), activating Src and FAK resulting in activation by phosphorylation of Akt, which induces hypoxia inducible factor 1-α (HIF-1α). The HIF-1α activates transcription of insulin growth factor-binding protein-2 (IGFBP-2), which is secreted thereby promoting angiogenesis and further induces endothelial cells to produce and secrete VEGF-A augmenting tumor angiogenesis. Our studies delineate an unanticipated cell nonautonomous function of MDA-9/syntenin in the context of angiogenesis, which may directly contribute to its metastasis-promoting properties. As a result, targeting MDA-9/syntenin or its downstream-regulated molecules may provide a means of simultaneously impeding metastasis by both directly inhibiting tumor cell transformed properties (autonomous) and indirectly by blocking angiogenesis (nonautonomous).

The transcription factor LSF: a novel oncogene for hepatocellular carcinoma

The transcription factor LSF (Late SV40 Factor), also known as TFCP2, belongs to the LSF/CP2 family related to Grainyhead family of proteins and is involved in many biological events, including regulation of cellular and viral promoters, cell cycle, DNA synthesis, cell survival and Alzheimer's disease. Our recent studies establish an oncogenic role of LSF in Hepatocellular carcinoma (HCC). LSF overexpression is detected in human HCC cell lines and in more than 90% cases of human HCC patients, compared to normal hepatocytes and liver, and its expression level showed significant correlation with the stages and grades of the disease. Forced overexpression of LSF in less aggressive HCC cells resulted in highly aggressive, angiogenic and multi-organ metastatic tumors in nude mice. Conversely, inhibition of LSF significantly abrogated growth and metastasis of highly aggressive HCC cells in nude mice. Microarray studies revealed that as a transcription factor LSF modulated specific genes regulating invasion, angiogenesis, chemoresistance and senescence. LSF transcriptionally regulates thymidylate synthase (TS) gene, thus contributing to cell cycle regulation and chemoresistance. Our studies identify a network of proteins, including osteopontin (OPN), Matrix metalloproteinase-9 (MMP-9), c-Met and complement factor H (CFH), that are directly regulated by LSF and play important role in LSF-induced hepatocarcinogenesis. A high throughput screening identified small molecule inhibitors of LSF DNA binding and the prototype of these molecules, Factor Quinolinone inhibitor 1 (FQI1), profoundly inhibited cell viability and induced apoptosis in human HCC cells without exerting harmful effects to normal immortal human hepatocytes and primary mouse hepatocytes. In nude mice xenograft studies, FQI1 markedly inhibited growth of human HCC xenografts as well as angiogenesis without exerting any toxicity. These studies establish a key role of LSF in hepatocarcinogenesis and usher in a novel therapeutic avenue for HCC, an invariably fatal disease.

Late SV40 factor (LSF) enhances angiogenesis by transcriptionally up-regulating matrix metalloproteinase-9 (MMP-9)

The transcription factor late SV40 factor (LSF) is overexpressed in human hepatocellular carcinoma (HCC) fostering a highly aggressive and metastatic phenotype. Angiogenesis is an essential component of cancer aggression and metastasis and HCC is a highly aggressive and angiogenic cancer. In the present studies, we analyzed the molecular mechanism of LSF-induced angiogenesis in HCC. Employing human umbilical vein endothelial cells (HUVEC) differentiation assay and chicken chorioallantoic membrane (CAM) assay we document that stable LSF overexpression augments and stable dominant negative inhibition of LSF (LSFdn) abrogates angiogenesis by human HCC cells. A quest for LSF-regulated factors contributing to angiogenesis, by chromatin immunoprecipitation-on-chip (ChIP-on-chip) assay, identified matrix metalloproteinase-9 (MMP-9) as a direct target of LSF. MMP-9 expression and enzymatic activity were higher in LSF-overexpressing cells and lower in LSFdn-expressing cells. Deletion mutation analysis identified the LSF-responsive regions in the MMP-9 promoter and ChIP assay confirmed LSF binding to the MMP-9 promoter. Inhibition of MMP-9 significantly abrogated LSF-induced angiogenesis as well as in vivo tumorigenesis, thus reinforcing the role of MMP-9 in facilitating LSF function. The present findings identify a novel target of LSF contributing to its oncogenic properties.

c-Met activation through a novel pathway involving osteopontin mediates oncogenesis by the transcription factor LSF

BACKGROUND & AIMS

Understanding the molecular pathogenesis of hepatocellular carcinoma (HCC) would facilitate development of targeted and effective therapies for this fatal disease. We recently demonstrated that the cellular transcription factor Late SV40 Factor (LSF) is overexpressed in more than 90% of human HCC cases, compared to the normal liver, and plays a seminal role in hepatocarcinogenesis. LSF transcriptionally upregulates osteopontin (OPN) that plays a significant role in mediating the oncogenic function of LSF. The present study aims at a better understanding of LSF function by analyzing the signaling pathway modulated by LSF.

METHODS

Phospho-receptor tyrosine kinase (RTK) array was performed to identify which receptor tyrosine kinases are activated by LSF. Immunohistochemical analysis using tissue microarray was performed to establish correlation among LSF, OPN, and phospho-c-Met levels in HCC patients. Co-immunoprecipitation analysis was performed to check OPN-induced CD44 and c-Met interaction. Inhibition studies using chemicals and siRNAs were performed in vitro and in vivo using nude mice xenograft models to establish the importance of c-Met activation in mediating LSF function.

RESULTS

Secreted OPN, induced by LSF, activates c-Met via a potential interaction between OPN and its cell surface receptor CD44. A significant correlation was observed among LSF, OPN, and activated c-Met levels in HCC patients. Chemical or genetic inhibition of c-Met resulted in profound abrogation of LSF-mediated tumorigenesis and metastasis in nude mice xenograft studies.

CONCLUSIONS

The present findings elucidate a novel pathway of c-Met activation during hepatocarcinogenesis and support the rationale of using c-Met inhibitors as potential HCC therapeutics.

Increased RNA-induced silencing complex (RISC) activity contributes to hepatocellular carcinoma

There is virtually no effective treatment for advanced hepatocellular carcinoma (HCC) and novel targets need to be identified to develop effective treatment. We recently documented that the oncogene Astrocyte elevated gene-1 (AEG-1) plays a seminal role in hepatocarcinogenesis. Employing yeast two-hybrid assay and coimmunoprecipitation followed by mass spectrometry, we identified staphylococcal nuclease domain containing 1 (SND1), a nuclease in the RNA-induced silencing complex (RISC) facilitating RNAi-mediated gene silencing, as an AEG-1 interacting protein. Coimmunoprecipitation and colocalization studies confirmed that AEG-1 is also a component of RISC and both AEG-1 and SND1 are required for optimum RISC activity facilitating small interfering RNA (siRNA) and micro RNA (miRNA)-mediated silencing of luciferase reporter gene. In 109 human HCC samples SND1 was overexpressed in ≈74% cases compared to normal liver. Correspondingly, significantly higher RISC activity was observed in human HCC cells compared to immortal normal hepatocytes. Increased RISC activity, conferred by AEG-1 or SND1, resulted in increased degradation of tumor suppressor messenger RNAs (mRNAs) that are target of oncomiRs. Inhibition of enzymatic activity of SND1 significantly inhibited proliferation of human HCC cells. As a corollary, stable overexpression of SND1 augmented and siRNA-mediated inhibition of SND1 abrogated growth of human HCC cells in vitro and in vivo, thus revealing a potential role of SND1 in hepatocarcinogenesis.

CONCLUSION

We unravel a novel mechanism that overexpression of AEG-1 and SND1 leading to increased RISC activity might contribute to hepatocarcinogenesis. Targeted inhibition of SND1 enzymatic activity might be developed as an effective therapy for HCC.