Recent advances in cancer fusion transcript detection.

Extensive investigation of gene fusions in cancer has led to the discovery of novel biomarkers and therapeutic targets. To date, most studies have neglected chromosomal rearrangement-independent fusion transcripts and complex fusion structures such as double or triple-hop fusions, and fusion-circRNAs. In this review, we untangle fusion-related terminology and propose a classification system involving both gene and transcript fusions. We highlight the importance of RNA-level fusions and how long-read sequencing approaches can improve detection and characterization. Moreover, we discuss novel bioinformatic tools to identify fusions in long-read sequencing data and strategies to experimentally validate and functionally characterize fusion transcripts.

Immune checkpoint inhibitors in HCC: Cellular, molecular and systemic data.

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer related deaths in the world, and for patients with advanced disease there are few therapeutic options available. The complex immunological microenvironment of HCC and the success of immunotherapy in several types of tumours, has raised the prospect of potential benefit for immune based therapies, such as immune checkpoint inhibitors (ICIs), in HCC. This has led to significant breakthrough research, numerous clinical trials and the rapid approval of multiple systemic drugs for HCC by regulatory bodies worldwide. Although some patients responded well to ICIs, many have failed to achieve significant benefit, while others showed unexpected and paradoxical deterioration. The aim of this review is to discuss the pathophysiology of HCC, the tumour microenvironment, key clinical trials evaluating ICIs in HCC, various resistance mechanisms to ICIs, and possible ways to overcome these impediments to improve patient outcomes.

A novel function for HEG1 in promoting metastasis in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) remains one of the leading causes of cancer-related deaths around the globe. For patients receiving liver tumour resection, the risk of reoccurrence and metastasis is high. Cancer metastasis can occur as a consequence of a physical change known as epithelial to mesenchymal transition (EMT). In this instance, cancer cells acquire migratory and invasive characteristics that allow the cells to move into adjacent tissue or enter the bloodstream to reach a secondary site, where they begin to form a new tumour. Targetting proteins involved in the signalling pathways that induce the mesenchymal phenotype has been an ongoing field of research. A recently published study has described a novel role for the heart development protein with EGF-like domains (HEG1) in promoting EMT. This research provides new insights into the biological function of this protein in HCC. Furthermore, the research indicates a new target for future prognostic and therapeutic research in HCC.

Adiponectin confers protection from acute colitis and restricts a B cell immune response.

Adiponectin demonstrates beneficial effects in various metabolic diseases, including diabetes, and in bowel cancer. Recent data also suggest a protective role in colitis. However, the precise molecular mechanisms by which adiponectin and its receptors modulate colitis and the nature of the adaptive immune response in murine models are yet to be elucidated. Adiponectin knock-out mice were orally administered dextran sulfate sodium for 7 days and were compared with wild-type mice. The severity of disease was analyzed histopathologically and through cytokine profiling. HCT116 colonic epithelial cells were employed to analyze the in vitro effects of adiponectin and AdipoR1 interactions in colonic injury following dextran sulfate sodium treatment. Adiponectin knock-out mice receiving dextran sulfate sodium exhibited severe colitis, had greater inflammatory cell infiltration, and an increased presence of activated B cells compared with controls. This was accompanied by an exaggerated proinflammatory cytokine profile and increased STAT3 signaling. Adiponectin knock-out mouse colons had markedly reduced proliferation and increased epithelial apoptosis and cellular stress. In vitro, adiponectin reduced apoptotic, anti-proliferative, and stress signals and restored STAT3 signaling. Following the abrogation of AdipoR1 in vitro, these protective effects of adiponectin were abolished. In summary, adiponectin maintains intestinal homeostasis and protects against murine colitis through interactions with its receptor AdipoR1 and by modulating adaptive immunity.

The role of AdipoR1 and AdipoR2 in liver fibrosis.

Activation of the adiponectin (APN) signaling axis retards liver fibrosis. However, understanding of the role of AdipoR1 and AdipoR2 in mediating this response is still rudimentary. Here, we sought to elucidate the APN receptor responsible for limiting liver fibrosis by employing AdipoR1 and AdipoR2 knock-out mice in the carbon tetrachloride (CCl4) model of liver fibrosis. In addition, we knocked down receptor function in primary hepatic stellate cells (HSCs) in vitro. Following the development of fibrosis, AdipoR1 and AdipoR2 KO mice had no quantitative difference in fibrosis by Sirius red staining. However, AdipoR2 KO mice had an enhanced fibrotic signature with increased Col1-α1, TGFß-1, TIMP-1, IL-10, MMP-2 and MMP-9. Knockdown of AdipoR1 or AdipoR2 in HSCs followed by APN treatment demonstrated that AdipoR1 and AdipoR2 did not affect proliferation or TIMP-1 gene expression, while AdipoR2 modulated Col1-α1 and α-SMA gene expression, HSC migration, and AMPK activity. These finding suggest that AdipoR2 is the major APN receptor on HSCs responsible for mediating its anti-fibrotic effects.

Dysregulated long noncoding RNAs (lncRNAs) in hepatocellular carcinoma: implications for tumorigenesis, disease progression, and liver cancer stem cells.

Hepatocellular carcinoma (HCC) is one of the most common malignant tumours with a poor prognosis worldwide. While early stage tumours can be treated with curative approaches such as liver transplantation or surgical resection, these are only suitable for a minority of patients. Those with advanced stage disease are only suitable for supportive approaches and most are resistant to the conventional chemotherapy or radiotherapy. Liver cancer stem cells (LCSCs) are a small subset of cancer cells with unlimited differentiation ability and tumour forming potential. In order to develop novel therapeutic approaches for HCC, we need to understand how the cancer develops and why treatment resistance occurs. Using high-throughput sequencing techniques, a large number of dysregulated long noncoding RNAs (lncRNAs) have been identified, and some of which are closely linked to key aspects of liver cancer pathology, progression, outcomes and for the maintenance of cancer stem cell-like properties. In addition, some lncRNAs are potential biomarkers for HCC diagnosis and may serve as the therapeutic targets. This review summarizes data recently reported lncRNAs that might be critical for the maintenance of the biological properties of LCSCs.

Adiponectin reduces hepatic stellate cell migration by promoting tissue inhibitor of metalloproteinase-1 (TIMP-1) secretion.

Hepatic stellate cells (HSC) are central players in liver fibrosis that when activated, proliferate, migrate to sites of liver injury, and secrete extracellular matrix. Obesity, a known risk factor for liver fibrosis is associated with reduced levels of adiponectin, a protein that inhibits liver fibrosis in vivo and limits HSC proliferation and migration in vitro. Adiponectin-mediated activation of adenosine monophosphate-activated kinase (AMPK) inhibits HSC proliferation, but the mechanism by which it limits HSC migration to sites of injury is unknown. Here we sought to elucidate how adiponectin regulates HSC motility. Primary rat HSCs were isolated and treated with adiponectin in migration assays. The in vivo actions of adiponectin were examined by treating mice with carbon tetrachloride for 12 weeks and then injecting them with adiponectin. Cell and tissue samples were collected and analyzed for gene expression, signaling, and histology. Serum from patients with liver fibrosis was examined for adiponectin and tissue inhibitor of metalloproteinase-1 (TIMP-1) protein. Adiponectin administration into mice increased TIMP-1 gene and protein expression. In cultured HSCs, adiponectin promoted TIMP-1 expression and through binding of TIMP-1 to the CD63/ß1-integrin complex reduced phosphorylation of focal adhesion kinase to limit HSC migration. In mice with liver fibrosis, adiponectin had similar effects and limited focal adhesion kinase phosphorylation. Finally, in patients with advanced fibrosis, there was a positive correlation between serum adiponectin and TIMP-1 levels. In sum, these data show that adiponectin stimulates TIMP-1 secretion by HSCs to retard their migration and contributes to the anti-fibrotic effects of adiponectin.

Effect of resveratrol on experimental non-alcoholic steatohepatitis.

Non-alcoholic fatty liver disease and non-alcoholic steatohepatitis (NASH) are increasing clinical problems for which effective treatments are required. The polyphenol resveratrol prevents the development of fatty liver disease in a number of experimental studies. We hypothesized that it could revert steatohepatitis, including hepatic inflammation and fibrosis, in an experimental NASH model. To induce hepatic steatohepatitis, a 65% fat, 2% cholesterol and 0.5% cholate (HFC) diet was fed to rats for 1 or 16 weeks, prior to treatment. Subsequently, the diet was supplemented with resveratrol (approx. 100mg/rat/day) to three intervention groups; week 2-4, 2-7 or 17-22. Treated animals were sacrificed at the end of each intervention period with appropriate control and HFC diet controls. Blood and liver were harvested for analysis. When commenced early, resveratrol treatment partially mitigated transaminase elevations, hepatic enlargement and TNFα induced protein-3 protein expression, but generally resveratrol treatment had no effect on elevated hepatic triglyceride levels, histological steatohepatitis or fibrosis. We observed a slight reduction in Collagen1α1 mRNA expression and no reduction in the mRNA expression of other markers of fibrosis, inflammation or steatosis (TGFß, TNFα, α2-MG, or SREBP-1c). Resveratrol metabolites were detected in serum, including trans-resveratrol-3-O-sulphate/trans-resveratrol-4'-O-sulphate (mean concentration 7.9 µg/ml). Contrary to the findings in experimental steatosis, resveratrol treatment had no consistent therapeutic effect in alleviating manifest experimental steatohepatitis.

Experimental nonalcoholic steatohepatitis compromises ureagenesis, an essential hepatic metabolic function.

Nonalcoholic steatohepatitis (NASH) is increasing in prevalence, yet its consequences for liver function are unknown. We studied ureagenesis, an essential metabolic liver function of importance for whole body nitrogen homeostasis, in a rodent model of diet-induced NASH. Rats were fed a high-fat, high-cholesterol diet for 4 and 16 wk, resulting in early and advanced experimental NASH, respectively. We examined the urea cycle enzyme mRNAs in liver tissue, the hepatocyte urea cycle enzyme proteins, and the in vivo capacity of urea-nitrogen synthesis (CUNS). Early NASH decreased all of the urea cycle mRNAs to an average of 60% and the ornithine transcarbamylase protein to 10%, whereas the CUNS remained unchanged. Advanced NASH further decreased the carbamoyl phosphate synthetase protein to 63% and, in addition, decreased the CUNS by 20% [from 5.65 ± 0.23 to 4.58 ± 0.30 µmol × (min × 100 g)(-1); P = 0.01]. Early NASH compromised the genes and enzyme proteins involved in ureagenesis, whereas advanced NASH resulted in a functional reduction in the capacity for ureagenesis. The pattern of urea cycle perturbations suggests a prevailing mitochondrial impairment by NASH. The decrease in CUNS has consequences for the ability of the body to adjust to changes in the requirements for nitrogen homeostasis e.g., at stressful events. NASH, thus, in terms of metabolic consequences, is not an innocuous lesion, and the manifestations of the damage seem to be a continuum with increasing disease severity.

Hepatic fat loss in advanced nonalcoholic steatohepatitis: are alterations in serum adiponectin the cause?

UNLABELLED: Advanced liver fibrosis in nonalcoholic steatohepatitis (NASH) is often accompanied by a reduction in hepatic fat to the point of complete fat loss (burnt-out NASH), but the mechanisms behind this phenomenon have not been elucidated. Adiponectin is raised in cirrhosis of any cause and has potent antisteatotic activity. In this study we examined 65 patients with advanced biopsy-proven NASH (fibrosis stage 3-4) and 54 with mild disease (fibrosis stage 0-1) to determine if disappearance of steatosis correlated with changes in serum adiponectin. All patents had fasting blood tests and anthropometric measures at the time of liver biopsy. Liver fat was accurately quantitated by morphometry. Serum adiponectin was measured by immunoassay. When compared to those with early disease, patients with advanced NASH were more insulin-resistant, viscerally obese, and older, but there was no difference in liver fat content or adiponectin levels. Adiponectin had a significant negative correlation with liver fat percentage in the whole cohort (r = -0.28, P < 0.01), driven by patients with advanced NASH (r = -0.40, P < 0.01). In advanced NASH, for each 4 µg/L increase in adiponectin there was an odds ratio OR of 2.0 (95% confidence interval [CI]: 1.3-3.0, P < 0.01) for a 5% reduction in hepatic fat. Adiponectin was highly and significantly associated with almost complete hepatic fat loss or burnt-out NASH (12.1 versus 7.4 µg/L, P = 0.001) on multivariate analysis. A relationship between adiponectin, bile acids, and adipocyte fexaramine activation was demonstrated in vivo and in vitro, suggestive of hepatocyte-adipocyte crosstalk. CONCLUSION: Serum adiponectin levels in advanced NASH are independently associated with hepatic fat loss. Adiponectin may in part be responsible for the paradox of burnt-out NASH. (HEPATOLOGY 2012).

ROCK1 inhibition promotes the self-renewal of a novel mouse mammary cancer stem cell.

The differentiation of stem-like tumor cells may contribute to the cellular heterogeneity of breast cancers. We report the propagation of highly enriched mouse mammary cancer stem cells that retain the potential to differentiate both in vivo and in culture and their use to identify chemical compounds that influence both self-renewal and differentiation. We identify epithelial tumor-initiating cells (ETICs) that express lineage markers of both basal and luminal mammary cell lineages and retain the potential, from even single cells, to generate heterogeneous tumors similar to the tumor of origin. ETICs can progress through a Rho-associated coiled-coil containing protein kinase 1 dependent, epithelial to mesenchymal transition to generate mesenchymal tumor-initiating cells capable of initiating tumors of limited heterogeneity. The propagation of ETICs may allow for the identification of new therapeutic compounds that may inhibit or prevent progression of some types of breast cancer.

Non-alcoholic steatohepatitis weakens the acute phase response to endotoxin in rats.

BACKGROUND & AIMS: Patients with non-alcoholic steatohepatitis (NASH) have increased mortality, including from infections. We, therefore, tested in a rodent model of steatohepatitis whether the hepatic acute phase response is intact. METHODS: Steatohepatitis was induced in rats by feeding a high-fat, high-cholesterol diet for 4 (early) and 16 weeks (advanced NASH). 2 h after low-dose LPS (0.5 mg/kg i.p.), we measured the serum concentrations of tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6). We also measured liver mRNA's and the serum concentrations of acute phase proteins 24 h after LPS. RESULTS: Non-alcoholic steatohepatitis in itself increased the liver mRNA levels of TNF-α and IL-6 and also the liver mRNA and serum levels of the acute phase proteins. The exposure to LPS increased serum TNF-α in both early and advanced NASH and more so than in the control rats. However, the increases in acute phase protein genes in liver tissue and proteins in the blood were lower than in the control rats. CONCLUSION: In rats with early or advanced experimental NASH, LPS despite an increased interleukin release resulted in a blunted acute phase protein response. This tachyphylaxis may be part of the mechanism for the increased infection susceptibility of patients with NASH. We speculate that the steatosis-related interleukin release desensitises the signalling pathway leading to acute phase protein synthesis.

Testing Cell Migration, Invasion, Proliferation, and Apoptosis in Hepatic Stellate Cells.

The hepatic wound repair process involves cell types including healthy and injured hepatocytes, Kupffer and inflammatory cells, sinusoidal endothelial cells (SECs), and hepatic stellate cells (HSCs). Normally, in their quiescent state, HSCs are a reservoir for vitamin A, but in response to hepatic injury, they become activated myofibroblasts that play a key role in the hepatic fibrotic response. Activated HSCs express extracellular matrix (ECM) proteins, elicit anti-apoptotic responses, and proliferate, migrate, and invade hepatic tissues to protect hepatic lobules from damage. Extended liver injury can lead to fibrosis and cirrhosis, the deposition of ECM that is driven by HSCs. Here we describe in vitro assays that quantify activated HSC responses in the presence of inhibitors targeting hepatic fibrosis.

Identifying cancer driver genes in individual tumours.

Cancer is a heterogeneous disease with a strong genetic component making it suitable for precision medicine approaches aimed at identifying the underlying molecular drivers within a tumour. Large scale population-level cancer sequencing consortia have identified many actionable mutations common across both cancer types and sub-types, resulting in an increasing number of successful precision medicine programs. Nonetheless, such approaches fail to consider the effects of mutations unique to an individual patient and may miss rare driver mutations, necessitating personalised approaches to driver-gene prioritisation. One approach is to quantify the functional importance of individual mutations in a single tumour based on how they affect the expression of genes in a gene interaction network (GIN). These GIN-based approaches can be broadly divided into those that utilise an existing reference GIN and those that construct de novo patient-specific GINs. These single-tumour approaches have several limitations that likely influence their results, such as use of reference cohort data, network choice, and approaches to mathematical approximation, and more research is required to evaluate the in vitro and in vivo applicability of their predictions. This review examines the current state of the art methods that identify driver genes in single tumours with a focus on GIN-based driver prioritisation.

Cell adhesion an important determinant of myogenesis and satellite cell activity.

Skeletal muscles represent a complex and highly organised tissue responsible for all voluntary body movements. Developed through an intricate and tightly controlled process known as myogenesis, muscles form early in development and are maintained throughout life. Due to the constant stresses that muscles are subjected to, skeletal muscles maintain a complex course of regeneration to both replace and repair damaged myofibers and to form new functional myofibers. This process, made possible by a pool of resident muscle stem cells, termed satellite cells, and controlled by an array of transcription factors, is additionally reliant on a diverse range of cell adhesion molecules and the numerous signaling cascades that they initiate. This article will review the literature surrounding adhesion molecules and their roles in skeletal muscle myogenesis and repair.

The role of DNA damage and repair in liver cancer.

Hepatocellular carcinoma is rapidly becoming a major cause of global mortality due to the ever-increasing prevalence of obesity. DNA damage is known to play an important role in cancer initiation, however DNA repair systems are also vital for the survival of cancer cells. Given the function of the liver and its exposure to the gut, it is likely that DNA damage and repair would be of particular importance in hepatocellular carcinoma. However, many contemporary reports have neglected the role of individual pathways of DNA damage and repair in their hypotheses. This review, therefore, aims to provide a concise overview for researchers in the field of liver cancer to understand the pathways of DNA damage and repair and their individual roles in hepatocellular carcinoma.

Targeting the PI3K/Akt/mTOR Pathway in Hepatocellular Carcinoma.

Despite advances in the treatment of cancers through surgical procedures and new pharmaceuticals, the treatment of hepatocellular carcinoma (HCC) remains challenging as reflected by low survival rates. The PI3K/Akt/mTOR pathway is an important signaling mechanism that regulates the cell cycle, proliferation, apoptosis, and metabolism. Importantly, deregulation of the PI3K/Akt/mTOR pathway leading to activation is common in HCC and is hence the subject of intense investigation and the focus of current therapeutics. In this review article, we consider the role of this pathway in the pathogenesis of HCC, focusing on its downstream effectors such as glycogen synthase kinase-3 (GSK-3), cAMP-response element-binding protein (CREB), forkhead box O protein (FOXO), murine double minute 2 (MDM2), p53, and nuclear factor-κB (NF-κB), and the cellular processes of lipogenesis and autophagy. In addition, we provide an update on the current ongoing clinical development of agents targeting this pathway for HCC treatments.

An aptamer-based drug delivery agent (CD133-apt-Dox) selectively and effectively kills liver cancer stem-like cells.

Liver cancer has no effective therapies, hence a poor survival. Cancer stem-like cells not only contribute to cancer initiation and progression, but also to drug resistance, cancer metastasis, and eventually treatment failure. Hence, any approaches that can effectively kill cancer stem-like cells hold a great potential for cancer treatment. CD133 is a robust marker for liver cancer stem-like cells. We developed a specific aptamer against CD133 (CD133-apt), and then loaded this aptamer with an anticancer drug doxorubicin (CD133-apt-Dox). The efficacy of CD133-apt-Dox in targeting liver cancer stem-like cells and its overall effect in treating liver cancer were investigated using multiple in vitro and in vivo studies including in patients-derived liver cancer organoids. We have observed that CD133-apt could preferably delivered doxorubicin to CD133-expressing cells with efficient drug accumulation and retention. CD133-apt-Dox impaired the self-renewal capacity of liver cancer stem-like cells and attenuated their stem-ness phenotypes in vitro or in vivo. CD133-apt-Dox significantly inhibited the growth of liver cancer cells and patients-derived organoids and reduced the growth of xenograft tumours in nude mice inhibited the growth of DEN-induced liver cancer in immunocompetent mice. Hence, aptamer-mediated targeting of CD133 is a highly promising approach for liver cancer therapy.

Adiponectin deficiency limits tumor vascularization in the MMTV-PyV-mT mouse model of mammary cancer.

PURPOSE: High levels of the fat-secreted cytokine adiponectin (APN) are present in the circulation of healthy people, whereas low levels correlate with an increased incidence of breast cancer in women. The current study experimentally probes the physiologic functions of APN in mammary cancer in a newly generated genetic mouse model. EXPERIMENTAL DESIGN: We established an APN null mouse model of mammary cancer by introducing the polyoma virus middle T (PyV-mT) oncogene expressed from mouse mammary tumor virus (MMTV) regulatory elements into APN null mice. MMTV-PyV-mT-induced tumors resemble ErbB2-amplified human breast cancers. We monitored tumor onset, kinetics, and animal survival, and analyzed vascular coverage, apoptosis, and hypoxia in sections from the primary tumors. Metastatic spreading was evaluated by analyses of the lungs. RESULTS: APN prominently localized to the vasculature in human and mouse mammary tumors. In APN null mice, MMTV-PyV-mT-induced tumors appeared with delayed onset and exhibited reduced growth rates. Affected animals survived control tumor-bearing mice by an average of 21 days. Pathologic analyses revealed reduced vascularization of APN null tumors along with increased hypoxia and apoptosis. At the experimental end point, APN null transgenic mice showed increased frequency of pulmonary metastases. CONCLUSION: The current work identifies a proangiogenic contribution of APN in mammary cancer that, in turn, affects tumor progression. APN interactions with vascular receptors may be useful targets for developing therapies aimed at controlling tumor vascularization in cancer patients.

A Sweet Connection? Fructose's Role in Hepatocellular Carcinoma.

Hepatocellular carcinoma is one of few cancer types that continues to grow in incidence and mortality worldwide. With the alarming increase in diabetes and obesity rates, the higher rates of hepatocellular carcinoma are a result of underlying non-alcoholic fatty liver disease. Many have attributed disease progression to an excess consumption of fructose sugar. Fructose has known toxic effects on the liver, including increased fatty acid production, increased oxidative stress, and insulin resistance. These effects have been linked to non-alcoholic fatty liver (NAFLD) disease and a progression to non-alcoholic steatohepatitis (NASH). While the literature suggests fructose may enhance liver cancer progression, the precise mechanisms in which fructose induces tumor formation remains largely unclear. In this review, we summarize the current understanding of fructose metabolism in liver disease and liver tumor development. Furthermore, we consider the latest knowledge of cancer cell metabolism and speculate on additional mechanisms of fructose metabolism in hepatocellular carcinoma.