Dysregulation of growth factor signaling in human hepatocellular carcinoma

The Curious Case of the HepG2 Cell Line: 40 Years of Expertise

Liver cancer is the third leading cause of cancer death worldwide. Representing such a dramatic impact on our lives, liver cancer is a significant public health concern. Sustainable and reliable methods for preventing and treating liver cancer require fundamental research on its molecular mechanisms. Cell lines are treated as in vitro equivalents of tumor tissues, making them a must-have for basic research on the nature of cancer. According to recent discoveries, certified cell lines retain most genetic properties of the original tumor and mimic its microenvironment. On the other hand, modern technologies allowing the deepest level of detail in omics landscapes have shown significant differences even between samples of the same cell line due to cross- and mycoplasma infection. This and other observations suggest that, in some cases, cell cultures are not suitable as cancer models, with limited predictive value for the effectiveness of new treatments. HepG2 is a popular hepatic cell line. It is used in a wide range of studies, from the oncogenesis to the cytotoxicity of substances on the liver. In this regard, we set out to collect up-to-date information on the HepG2 cell line to assess whether the level of heterogeneity of the cell line allows in vitro biomedical studies as a model with guaranteed production and quality.

DNAzymes, Novel Therapeutic Agents in Cancer Therapy: A Review of Concepts to Applications

The past few decades have witnessed a rapid evolution in cancer drug research which is aimed at developing active biological interventions to regulate cancer-specific molecular targets. Nucleic acid-based therapeutics, including ribozymes, antisense oligonucleotides, small interference RNA (siRNA), aptamer, and DNAzymes, have emerged as promising candidates regulating cancer-specific genes at either the transcriptional or posttranscriptional level. Gene-specific catalytic DNA molecules, or DNAzymes, have shown promise as a therapeutic intervention against cancer in various in vitro and in vivo models, expediting towards clinical applications. DNAzymes are single-stranded catalytic DNA that has not been observed in nature, and they are synthesized through in vitro selection processes from a large pool of random DNA libraries. The intrinsic properties of DNAzymes like small molecular weight, higher stability, excellent programmability, diversity, and low cost have brought them to the forefront of the nucleic acid-based therapeutic arsenal available for cancers. In recent years, considerable efforts have been undertaken to assess a variety of DNAzymes against different cancers. However, their therapeutic application is constrained by the low delivery efficiency, cellular uptake, and target detection within the tumour microenvironment. Thus, there is a pursuit to identify efficient delivery methods in vivo before the full potential of DNAzymes in cancer therapy is realized. In this light, a review of the recent advances in the use of DNAzymes against cancers in preclinical and clinical settings is valuable to understand its potential as effective cancer therapy. We have thus sought to firstly provide a brief overview of construction and recent improvements in the design of DNAzymes. Secondly, this review stipulates the efficacy, safety, and tolerability of DNAzymes developed against major hallmarks of cancers tested in preclinical and clinical settings. Lastly, the recent advances in DNAzyme delivery systems along with the challenges and prospects for the clinical application of DNAzymes as cancer therapy are also discussed.

A MET-PTPRK kinase-phosphatase rheostat controls ZNRF3 and Wnt signaling

Zinc and ring finger 3 (ZNRF3) is a transmembrane E3 ubiquitin ligase that targets Wnt receptors for ubiquitination and lysosomal degradation. Previously, we showed that dephosphorylation of an endocytic tyrosine motif (4Y motif) in ZNRF3 by protein tyrosine phosphatase receptor-type kappa (PTPRK) promotes ZNRF3 internalization and Wnt receptor degradation (Chang et al 2020). However, a responsible protein tyrosine kinase(s) (PTK) phosphorylating the 4Y motif remained elusive. Here we identify the proto-oncogene MET (mesenchymal-epithelial transition factor) as a 4Y kinase. MET binds to ZNRF3 and induces 4Y phosphorylation, stimulated by the MET ligand HGF (hepatocyte growth factor, scatter factor). HGF-MET signaling reduces ZNRF3-dependent Wnt receptor degradation thereby enhancing Wnt/β-catenin signaling. Conversely, depletion or pharmacological inhibition of MET promotes the internalization of ZNRF3 and Wnt receptor degradation. We conclude that HGF-MET signaling phosphorylates- and PTPRK dephosphorylates ZNRF3 to regulate ZNRF3 internalization, functioning as a rheostat for Wnt signaling that may offer novel opportunities for therapeutic intervention.

Insights into Growth Factors in Liver Carcinogenesis and Regeneration: An Ongoing Debate on Minimizing Cancer Recurrence after Liver Resection

Hepatocellular carcinoma has become a leading cause of cancer-associated mortality throughout the world, and is of great concern. Currently used chemotherapeutic drugs in the treatment of hepatocellular carcinoma lead to severe side effects, thus underscoring the need for further research to develop novel and safer therapies. Liver resection in cancer patients is routinely performed. After partial resection, liver regeneration is a perfectly calibrated response apparently sensed by the body’s required liver function. This process hinges on the effect of several growth factors, among other molecules. However, dysregulation of growth factor signals also leads to growth signaling autonomy and tumor progression, so control of growth factor expression may prevent tumor progression. This review describes the role of some of the main growth factors whose dysregulation promotes liver tumor progression, and are also key in regenerating the remaining liver following resection. We herein summarize and discuss studies focused on partial hepatectomy and liver carcinogenesis, referring to hepatocyte growth factor, insulin-like growth factor, and epidermal growth factor, as well as their suitability as targets in the treatment of hepatocellular carcinoma. Finally, and given that drugs remain one of the mainstay treatment options in liver carcinogenesis, we have reviewed the current pharmacological approaches approved for clinical use or research targeting these factors.

Ameliorative effects of colostrum against DMBA hepatotoxicity in rats

Colostrum, the sole diet for newborns, is an emerging nutraceutical. To date, the chemopreventive effect of Bovine Colostrum against liver injury induced by the potent carcinogen, 7,12-dimethyl-Benz[a]anthracene (DMBA) is unexplored. Humans are daily exposed to DMBA which is a highly lipophilic environmental organic pollutant. The study aimed to investigate the hepatoprotective role of Bovine Colostrum against DMBA-induced hepatotoxicity using a rat model. Fifty male rats were divided into five groups; GI (control), GII (olive oil, vehicle for DMBA), GIII (DMBA), GIV (DMBA + Bovine Colostrum), GV (Bovine Colostrum). After 12 weeks, body weight changes and mortality were calculated. Histological and ultrastructural examinations of liver tissue were performed. Expressions of p53, TGFβ2, TNF-α, S6K2, and c20orf20 were assessed by RT-PCR. Post-treatment with Bovine Colostrum increased both the body weight and the survival rate of rats treated with DMBA. In addition, remarkable protection against the pathological effect of DMBA was noted. Ultrastructurally, Bovine Colostrum ameliorated/prevented most of the toxic effects of DMBA on hepatocytes, including irregularities of nuclear envelope, clumping, and margination of heterochromatin aggregates, segregated nucleoli, and mitochondrial pleomorphism. Bovine Colostrum administration down-regulated p53, C20orf20, and S6K2 mRNA levels, and up-regulated TNF-α and TGFβ2. In conclusion, Bovine Colostrum have a protective effect against DMBA-induced toxicity on the liver of albino rats. Consequently, Bovine Colostrum may prevent polycyclic aromatic hydrocarbons-induced hepatotoxicity and may be useful in promoting human health if supplemented in the diet.

GLP-1 reduces the migration of hepatocellular carcinoma cells via suppression of the stress-activated protein kinase/c-Jun N-terminal kinase pathway

Incretins, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), are hormones secreted from small intestine accompanied with oral intake. We previously showed that transforming growth factor (TGF)-α stimulates the migration of hepatocellular carcinoma (HCC) cells via mitogen-activated protein (MAP) kinases, AKT and Rho-kinase. However, it remains to be elucidated whether incretins affect HCC cell functions. In the present study, therefore, we investigated whether incretins affect the migration of HCC cells using human HCC-derived HuH7 cells. GLP-1, but not GIP, reduced both TGF-α- and hepatocyte growth factor (HGF)-induced cell migration. IBMX, an inhibitor of cyclic nucleotide phosphodiesterase, enhanced the suppressive effect of GLP-1. GLP-1 attenuated the phosphorylation of stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) by TGF-α and HGF. Our results strongly suggest that GLP-1 suppresses TGF-α- and HGF-induced migration of HCC cells through inhibiting the SAPK/JNK signaling pathway, and that the inhibition by GLP-1 is due to cAMP production.

Piptides: New, Easily Accessible Chemotypes For Interactions With Biomolecules

Small molecule probe development is pivotal in biomolecular science. Research described here was undertaken to develop a non-peptidic chemotype, piptides, that is amenable to convenient, iterative solid-phase syntheses, and useful in biomolecular probe discovery. Piptides can be made from readily accessible pip acid building blocks and have good proteolytic and pH stabilities. An illustrative application of piptides against a protein-protein interaction (PPI) target was explored. The Exploring Key Orientations (EKO) strategy was used to evaluate piptide candidates for this. A library of only 14 piptides contained five members that disrupted epidermal growth factor (EGF) and its receptor, EGFR, at low micromolar concentrations. These piptides also caused apoptotic cell death, and antagonized EGF-induced phosphorylation of intracellular tyrosine residues in EGFR.

Imbalance of TGF-β1/BMP-7 pathways induced by M2-polarized macrophages promotes hepatocellular carcinoma aggressiveness

The transforming growth factor-beta (TGF-β) signaling pathway is the predominant cytokine signaling pathway in the development and progression of hepatocellular carcinoma (HCC). Bone morphogenetic protein (BMP), another member of the TGF-β superfamily, has been frequently found to participate in crosstalk with the TGF-β pathway. However, the complex interaction between the TGF-β and BMP pathways has not been fully elucidated in HCC. We found that the imbalance of TGF-β1/BMP-7 pathways was associated with aggressive pathological features and poor clinical outcomes in HCC. The induction of the imbalance of TGF-β1/BMP-7 pathways in HCC cells could significantly promote HCC cell invasion and stemness by increasing inhibitor of differentiation 1 (ID1) expression. We also found that the microRNA (miR)-17-92 cluster, originating from the extracellular vesicles (EVs) of M2-polarized tumor-associated macrophages (M2-TAMs), stimulated the imbalance of TGF-β1/BMP-7 pathways in HCC cells by inducing TGF-β type II receptor (TGFBR2) post-transcriptional silencing and inhibiting activin A receptor type 1 (ACVR1) post-translational ubiquitylation by targeting Smad ubiquitylation regulatory factor 1 (Smurf1). In vivo, short hairpin (sh)-MIR17HG and ACVR1 inhibitors profoundly attenuated HCC cell growth and metastasis by rectifying the imbalance of TGF-β1/BMP-7 pathways. Therefore, we proposed that the imbalance of TGF-β1/BMP-7 pathways is a feasible prognostic biomarker and recovering the imbalance of TGF-β1/BMP-7 pathways might be a potential therapeutic strategy for HCC.

The Role of Autophagy in Liver Cancer: Crosstalk in Signaling Pathways and Potential Therapeutic Targets

Autophagy is an evolutionarily conserved lysosomal-dependent pathway for degrading cytoplasmic proteins, macromolecules, and organelles. Autophagy-related genes (Atgs) are the core molecular machinery in the control of autophagy, and several major functional groups of Atgs coordinate the entire autophagic process. Autophagy plays a dual role in liver cancer development via several critical signaling pathways, including the PI3K-AKT-mTOR, AMPK-mTOR, EGF, MAPK, Wnt/β-catenin, p53, and NF-κB pathways. Here, we review the signaling pathways involved in the cross-talk between autophagy and hepatocellular carcinoma (HCC) and analyze the status of the development of novel HCC therapy by targeting the core molecular machinery of autophagy as well as the key signaling pathways. The induction or the inhibition of autophagy by the modulation of signaling pathways can confer therapeutic benefits to patients. Understanding the molecular mechanisms underlying the cross-link of autophagy and HCC may extend to translational studies that may ultimately lead to novel therapy and regimen formation in HCC treatment.

Incidence of Hepatocellular Carcinoma after Treatment with Sofosbuvir-Based or Sofosbuvir-Free Regimens in Patients with Chronic Hepatitis C

Simple Summary

The development of hepatocellular carcinoma (HCC) has not been well-controlled, even after the elimination of hepatitis C virus (HCV), especially for those with cirrhosis or of high-age. Fibrosis-related biomarkers have been recognized as useful predictors for the development of HCC; however, there are few analyses of the HCC incidence for the various regimens with direct-acting antivirals (DAA). We found that DAA treatment with sofosbuvir, an oral nucleotide analogue inhibitor of HCV NS5B polymerase, was not associated with the development of de novo HCC within five years by propensity score matched analysis. Moreover, the distribution of the early stage of HCC (the Barcelona Clinic Liver Cancer stage 0/A) was similar for all treatment regimens, irrespective of the use of sofosbuvir.

Abstract

Advanced fibrosis/cirrhosis and related biomarkers have been recognized as useful predictors of the development of hepatocellular carcinoma (HCC) by patients with chronic hepatitis C (CHC) following hepatitis C virus (HCV) cure by direct-acting antivirals (DAAs). However, it remains unclear if DAAs themselves have an influence on or facilitate the development of HCC. This multicenter cohort study included CHC patients without a history of HCC who achieved HCV elimination by DAAs. Cohorts of 835 patients treated with a sofosbuvir (SOF)-based regimen and 835 treated with a SOF-free regimen were matched 1:1 by propensity scoring with nine variables to evaluate differences in HCC incidence. The median observation period was 3.5 years. Sixty-nine cases of HCC were found during 5483.9 person-years (PY) over the entire follow-up period. The annual incidence was similar for both groups (SOF-based 1.25 and SOF-free 1.27 per 100 PY, respectively: adjusted hazard ratio (HR) 1.26, 95% confidence interval (CI) 0.75–2.12, p = 0.39). However, the annual incidence within the first two years was higher for patients treated with SOF than for those without, but did not reach significance (1.50 and 0.97 per 100 PY incidence rates, respectively: adjusted HR 2.05, 95% CI 0.98–4.25, p = 0.06). In summary, DAA treatment with SOF was not associated with an increase in the development of de novo HCC.

Heat shock protein 70 positively regulates transforming growth factor-α-induced hepatocellular carcinoma cell migration via the AKT signaling pathway

Heat shock proteins (HSPs) are induced in response to extracellular stress and manage the quality of proteins as molecular chaperones. HSP70, a highly conserved HSP, has been reported to correlate with the proliferation and migration of human cancer cells, such as oral, prostate, lung and liver cancer. Regarding hepatocellular carcinoma (HCC), the HSP70 levels in the tumor tissues from patients are significantly higher than those in the normal liver tissues. HSP70 reportedly upregulates the migration and invasion of HCC. The AKT, p38 mitogen-activated protein kinase (MAPK), c-jun N-terminal kinase (JNK) and Rho-kinase signaling pathways regulate the transforming growth factor (TGF)-α-induced migration of human HCC-derived HuH7 cells. However, the exact mechanism underlying the role of HSP70 in growth factor-induced HCC migration remains unclear. Therefore, in the present study, the mechanism underlying the involvement of HSP70 in TGF-α-induced HCC cell migration was investigated. Treatment with the HSP70 inhibitors VER155008 and YM-08 and the downregulation of HSP70 protein were confirmed to significantly suppress the TGF-α-induced cell migration of HuH7 cells. Both VER155008 and YM-08 reduced the TGF-α-induced phosphorylation of AKT without affecting the phosphorylation of p38 MAPK, JNK or Rho-kinase. These results strongly suggest that HSP70 positively regulates the TGF-α-induced migration of HCC cells via the AKT signaling pathway.

A newly discovered role of metabolic enzyme PCK1 as a protein kinase to promote cancer lipogenesis

Highly active lipogenesis is essential for rapid tumor growth. Sterol regulatory element‐binding protein (SREBP) is a key transcriptional factor for lipogenesis and activated by reduced sterol and oxysterol levels. However, the mechanism by which cancer cells activate SREBP without altering these sterol/oxysterol levels remains elusive. In one of our recent studies published in Nature entitled “The gluconeogenic enzyme PCK1 phosphorylates INSIG1/2 for lipogenesis”, we demonstrated that activated AKT‐mediated phosphoenolpyruvate carboxykinase 1 (PCK1) S90 phosphorylation reduces the gluconeogenic activity of PCK1 and triggers its translocation to the endoplasmic reticulum (ER), where PCK1 acts as a protein kinase and uses GTP, rather than ATP, as a phosphate donor to phosphorylate Insig1/2 thereby reducing oxysterol's binding to Insig1/2 and activating SREBP‐mediated lipogenesis for tumor growth. These findings elucidate a coordinated regulation between gluconeogenesis and lipogenesis and uncover a critical role of the protein kinase activity of PCK1 in SREBP‐dependent lipid synthesis.

Promotion of liver regeneration and anti‑fibrotic effects of the TGF‑β receptor kinase inhibitor galunisertib in CCl4‑treated mice

The cytokine transforming growth factor‑β (TGF‑β) serves a key role in hepatic fibrosis and has cytostatic effects on hepatocytes. The present study investigated the anti‑fibrogenic and regenerative effects of the TGF‑β receptor type I kinase inhibitor galunisertib (LY2157299) in mice with carbon tetrachloride (CCl4)‑induced liver cirrhosis and in vitro. Mice were intraperitoneally treated with CCl4 for 8 weeks. At week 5, the mice were divided randomly into four treatment groups: Vehicle‑treated; and treated with low‑; middle‑; and high‑dose galunisertib, which was administered from weeks 5‑8. The mice were sacrificed after 8 weeks of CCl4 treatment. Liver fibrosis, as evaluated by histology and determination of hydroxyproline content, progressed during week 4‑8 of CCl4 treatment in the vehicle‑treated mice. Galunisertib treatment dose‑dependently prevented liver fibrosis, as demonstrated by the direct inhibition of α‑smooth muscle actin‑positive activated hepatic stellate cells (HSCs) after 8 weeks of CCl4 treatment. The levels of active matrix metalloproteinase (MMP)‑9 in galunisertib‑treated livers were significantly increased compared with the vehicle‑treated livers. In the high‑dose group, the number of PCNA‑positive hepatocytes and endothelial cells markedly increased compared with the vehicle group. Reverse transcription‑quantitative PCR analysis verified that interleukin‑6 and epiregulin expression levels were significantly increased in livers from the group treated with high‑dose galunisertib compared with the vehicle‑treated group. Galunisertib inhibited the proliferation of activated HSCs and collagen synthesis in addition to restoring MMP activity. Moreover, galunisertib promoted liver remodeling by proliferating hepatocytes and vascular endothelial cells, while significantly increasing liver weight. These results are consistent with the cytostatic action of TGF‑β that negatively regulates liver regeneration, and demonstrated that galunisertib inhibited TGF‑β signaling, halted liver fibrosis progression and promoted hepatic regeneration. The results of the present study suggest that galunisertib may be an effective treatment for liver cirrhosis.

The gluconeogenic enzyme PCK1 phosphorylates INSIG1/2 for lipogenesis

Cancer cells increase lipogenesis for their proliferation and the activation of sterol regulatory element-binding proteins (SREBPs) has a central role in this process. SREBPs are inhibited by a complex composed of INSIG proteins, SREBP cleavage-activating protein (SCAP) and sterols in the endoplasmic reticulum. Regulation of the interaction between INSIG proteins and SCAP by sterol levels is critical for the dissociation of the SCAP-SREBP complex from the endoplasmic reticulum and the activation of SREBPs^1,2. However, whether this protein interaction is regulated by a mechanism other than the abundance of sterol-and in particular, whether oncogenic signalling has a role-is unclear. Here we show that activated AKT in human hepatocellular carcinoma (HCC) cells phosphorylates cytosolic phosphoenolpyruvate carboxykinase 1 (PCK1), the rate-limiting enzyme in gluconeogenesis, at Ser90. Phosphorylated PCK1 translocates to the endoplasmic reticulum, where it uses GTP as a phosphate donor to phosphorylate INSIG1 at Ser207 and INSIG2 at Ser151. This phosphorylation reduces the binding of sterols to INSIG1 and INSIG2 and disrupts the interaction between INSIG proteins and SCAP, leading to the translocation of the SCAP-SREBP complex to the Golgi apparatus, the activation of SREBP proteins (SREBP1 or SREBP2) and the transcription of downstream lipogenesis-related genes, proliferation of tumour cells, and tumorigenesis in mice. In addition, phosphorylation of PCK1 at Ser90, INSIG1 at Ser207 and INSIG2 at Ser151 is not only positively correlated with the nuclear accumulation of SREBP1 in samples from patients with HCC, but also associated with poor HCC prognosis. Our findings highlight the importance of the protein kinase activity of PCK1 in the activation of SREBPs, lipogenesis and the development of HCC.

Therapeutic modulators of hepatic stellate cells for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common type of primary tumor in the liver and is a leading cause of cancer-related death worldwide. Activated hepatic stellate cells (HSCs) are key components of the HCC microenvironment and play an important role in the onset and progression of HCC through the secretion of growth factors and cytokines. Current treatment modalities that include chemotherapy, radiotherapy and ablation are able to activate HSCs and remodel the tumor microenvironment. Growing evidence has demonstrated that the complex interaction between activated HSCs and tumor cells can facilitate cancer chemoresistance and metastasis. Therefore, therapeutic targeting of activated HSCs has emerged as a promising strategy to improve treatment outcomes for HCC. This review summarizes the molecular mechanisms of HSC activation triggered by treatment modalities, the function of activated HSCs in HCC, as well as the crosstalk between tumor cells and activated HSCs. Pathways of activated HSC reduction are discussed, including inhibition, apoptosis, and reversion to the inactivated state. Finally, we outline the progress and challenges of therapeutic approaches targeting activated HSCs in the development of HCC treatment.

Genomic Perspective on Mouse Liver Cancer Models

Selecting the most appropriate mouse model that best recapitulates human hepatocellular carcinoma (HCC) allows translation of preclinical mouse studies into clinical studies. In the era of cancer genomics, comprehensive and integrative analysis of the human HCC genome has allowed categorization of HCC according to molecular subtypes. Despite the variety of mouse models that are available for preclinical research, there is a lack of evidence for mouse models that closely resemble human HCC. Therefore, it is necessary to identify the accurate mouse models that represent human HCC based on molecular subtype as well as histologic aggressiveness. In this review, we summarize the mouse models integrated with human HCC genomic data to provide information regarding the models that recapitulates the distinct aspect of HCC biology and prognosis based on molecular subtypes.

HNF4α-Deficient Fatty Liver Provides a Permissive Environment for Sex-Independent Hepatocellular Carcinoma

The incidence of hepatocellular carcinoma (HCC) is on the rise worldwide. Although the incidence of HCC in males is considerably higher than in females, the projected rates of HCC incidence are increasing for both sexes. A recently appreciated risk factor for HCC is the growing problem of nonalcoholic fatty liver disease, which is usually associated with obesity and the metabolic syndrome. In this study, we showed that under conditions of fatty liver, female mice were more likely to develop HCC than expected from previous models. Using an inducible knockout model of the tumor-suppressive isoform of hepatocyte nuclear factor 4 alpha ("P1-HNF4α") in the liver in combination with prolonged high fat (HF) diet, we found that HCC developed equally in male and female mice as early as 38 weeks of age. Similar sex-independent HCC occurred in the "STAM" model of mice, in which severe hyperglycemia and HF feeding results in rapid hepatic lipid deposition, fibrosis, and ultimately HCC. In both sexes, reduced P1-HNF4α activity, which also occurs under chronic HF diet feeding, increased hepatic lipid deposition and produced a greatly augmented circadian rhythm in IL6, a factor previously linked with higher HCC incidence in males. Loss of HNF4α combined with HF feeding induced epithelial-mesenchymal transition in an IL6-dependent manner. Collectively, these data provide a mechanism-based working hypothesis that could explain the rising incidence of aggressive HCC. SIGNIFICANCE: This study provides a mechanism for the growing incidence of hepatocellular carcinoma in both men and women, which is linked to nonalcoholic fatty liver disease.

MAT2B mediates invasion and metastasis by regulating EGFR signaling pathway in hepatocellular carcinoma

The poor prognosis of hepatocellular carcinoma (HCC) patients is mainly due to cancer metastasis. Methionine adenosyltransferase 2β (MAT2B) encodes a regulatory subunit (β) for methionine adenosyltransferase. Previous studies reveal that MAT2B provides a growth advantage for HCC, but its role in metastasis is unknown. This study showed that both in the xenograft zebra fish model and in the lung metastasis model in nude mice, the stable inhibition of MAT2B could suppress the metastasis of HCC cancer cells. Silencing of MAT2B in HCC cell lines could remarkably inhibit migration and invasion. By analysis of human phospho-kinase array membranes, we found several differentially expressed proteins, including phosphor-AKT, phospho-EGFR, phospho-Src family, phospho-FAK, phospho-STAT3 and phospho-ERK. We further confirmed the change of these EGFR pathway-related proteins was in accordance with MAT2B expression pattern through immunoblotting test. Finally, we found that MAT2B was overexpressed in HCC caner tissues and correlated with poor prognosis for HCC patients in clinical manifestation. Our study demonstrated that silencing of MAT2B could suppress liver cancer cell migration and invasion through the inhibition of EGFR signaling, which suggested that MAT2B might serve as a new prognostic marker and therapeutic target for HCC.

Anti-apoptotic effect by the suppression of IRF1 as a downstream of Wnt/β-catenin signaling in colorectal cancer cells

Impaired Wnt signaling pathway plays a crucial role in the development of colorectal cancer through activation of the β-catenin/TCF7L2 complex. Although genes upregulated by Wnt/β-catenin signaling have been intensively studied, the roles of downregulated genes are poorly understood. Previously, we reported that interferon-induced proteins with tetratricopeptide repeats 2 (IFIT2) was downregulated by the Wnt/β-catenin signaling, and that the suppressed expression of IFIT2 conferred antiapoptotic property to colorectal cancer (CRC) cells. However, the mechanisms underlying how Wnt/β-catenin signaling regulates IFIT2 remain to be elucidated. In this study, we have uncovered that the expression of IFIT2 is induced by IRF1, which is negatively regulated by the Wnt/β-catenin signaling. In addition, we found that downregulation of IRF1 is mediated by its degradation through the ubiquitination-proteasome pathway, and that decreased activity of a deubiquitinase complex containing USP1 and UAF1 is involved in the degradation of IRF1 by Wnt/β-catenin signaling. These data should provide better understanding of the Wnt signaling pathway and human carcinogenesis.

APLN promotes hepatocellular carcinoma through activating PI3K/Akt pathway and is a druggable target

Background: The pathogenesis of hepatocellular carcinoma (HCC) is a multistep process contributed by the accumulation of molecular alterations. We identified Apelin (APLN) as an outlier gene up-regulated in hepatocellular carcinoma (HCC) through RNA-Seq and microarray analysis. We aimed to investigate its function, mechanism of action and clinical implication in HCC. Methods: Gene expression and clinical implication of APLN were assessed in multiple human HCC cohorts. Ectopic expression and silencing of APLN were performed to determine its function. The therapeutic potential of APLN and its downstream pathway was investigated using in vitro and in vivo models. Results: APLN overexpression was commonly observed in more than 80% of HCCs and independently predicted poorer survival of patients in three independent HCC cohorts. Apelin up-regulation was mediated by active β-catenin, which binds to the APLN promoter to induce transcription. Ectopic APLN expression in HCC cells promoted cell proliferation, accelerated G1/S progression and inhibited apoptosis, whilst APLN knockdown exerted opposite effects in vitro and inhibited HCC xenograft growth in mice. Mechanistically, APLN activated phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) pathway via APLN receptor, leading to increased expression of phospho-glycogen synthase kinase 3β (p-GSK3β) and cyclin D1. Pharmacological targeting of APLN by ML221 was safe and effective in inhibiting APLN-PI3K/Akt cascade and HCC growth in vitro and in vivo. Conclusions: Our findings unraveled an oncogenic role of APLN in HCC, and that targeting of APLN might be a promising for HCC treatment. APLN may serve as an independent prognostic factor for HCC patients.

Hepatocyte growth control by SOCS1 and SOCS3

The extraordinary capacity of the liver to regenerate following injury is dependent on coordinated and regulated actions of cytokines and growth factors. Whereas hepatocyte growth factor (HGF) and epidermal growth factor (EGF) are direct mitogens to hepatocytes, inflammatory cytokines such as TNFα and IL-6 also play essential roles in the liver regeneration process. These cytokines and growth factors activate different signaling pathways in a sequential manner to elicit hepatocyte proliferation. The kinetics and magnitude of these hepatocyte-activating stimuli are tightly regulated to ensure restoration of a functional liver mass without causing uncontrolled cell proliferation. Hepatocyte proliferation can become deregulated under conditions of chronic inflammation, leading to accumulation of genetic aberrations and eventual neoplastic transformation. Among the control mechanisms that regulate hepatocyte proliferation, negative feedback inhibition by the 'suppressor of cytokine signaling (SOCS)' family proteins SOCS1 and SOCS3 play crucial roles in attenuating cytokine and growth factor signaling. Loss of SOCS1 or SOCS3 in the mouse liver increases the rate of liver regeneration and renders hepatocytes susceptible to neoplastic transformation. The frequent epigenetic repression of the SOCS1 and SOCS3 genes in hepatocellular carcinoma has stimulated research in understanding the growth regulatory mechanisms of SOCS1 and SOCS3 in hepatocytes. Whereas SOCS3 is implicated in regulating JAK-STAT signaling induced by IL-6 and attenuating EGFR signaling, SOCS1 is crucial for the regulation of HGF signaling. These two proteins also module the functions of certain key proteins that control the cell cycle. In this review, we discuss the current understanding of the functions of SOCS1 and SOCS3 in controlling hepatocyte proliferation, and its implications to liver health and disease.

Heat Shock Protein 90α-Dependent B-Cell-2-Associated Transcription Factor 1 Promotes Hepatocellular Carcinoma Proliferation by Regulating MYC Proto-Oncogene c-MYC mRNA Stability

B-cell lymphoma 2 (Bcl-2)-associated transcription factor 1 (Bclaf1) is known to be involved in diverse biological processes, but, to date, there has been no evidence for any functional role of Bclaf1 in hepatocellular carcinoma (HCC) progression. Here, we demonstrate that Bclaf1 is frequently up-regulated in HCC and that Bclaf1 up-regulation is associated with Edmondson grade, lower overall survival rates, and poor prognosis. Overexpression of Bclaf1 in HCC cell lines HepG2 and Huh7 promoted proliferation considerably, whereas Bclaf1 knockdown had the opposite effect. Xenograft tumors grown from Bclaf1 knockdown Huh7 cells had smaller tumor volumes than tumors grown from control cells. Furthermore, our study describes MYC proto-oncogene (c-Myc) as a downstream target of Bclaf1, given that Bclaf1 regulates c-MYC expression posttranscriptionally by its RS domain. To exert this function, Bclaf1 must interact with the molecular chaperone, heat shock protein 90 alpha (Hsp90α). In HCC tissue samples, Hsp90α levels were also increased significantly and Hsp90α-Bclaf1 interaction was enhanced. Bclaf1 interacts with the C-terminal domain of Hsp90α, and this interaction is disrupted by the C-terminal domain inhibitor, novobiocin (NB), resulting in proteasome-dependent degradation of Bclaf1. Moreover, NB-induced disruption of Hsp90α-Bclaf1 interaction dampened the production of mature c-MYC mRNA and attenuated tumor cell growth in vitro and in vivo. Conclusion: Our findings suggest that Bclaf1 affects HCC progression by manipulating c-MYC mRNA stability and that the Hsp90α/Bclaf1/c-Myc axis might be a potential target for therapeutic intervention in HCC.

Systems Challenges of Hepatic Carcinomas: A Review

Hepatocellular Carcinoma (HCC) is ubiquitous in its prevalence in most of the developing countries. In the era of systems biology, multi-omics has evinced an extensive approach to define the underlying mechanism of disease progression. HCC is a multifactorial disease and the investigation of progression of liver cirrhosis becomes much extensive with cultivating omics approaches. We have performed a comprehensive review about such challenges in multi-omics approaches that are concerned to identify the immunological, genetics and epidemiological factors associated with HCC.

Methylation in MIRLET7A3 Gene Induces the Expression of IGF-II and Its mRNA Binding Proteins IGF2BP-2 and 3 in Hepatocellular Carcinoma

miR-let-7a is a tumor suppressor miRNA with reduced expression in most cancers. Methylation of MIRLET7A3 gene was reported to be the cause of this suppression in several cancers; however, it was not explicitly investigated in hepatocellular carcinoma (HCC). We aimed at investigating miR-let-7a expression and molecular mode in HCC, identifying drug-targetable networks, which might be affected by its abundance. Our results illustrated a significant repression of miR-let-7a, which correlated with hypermethylation of its gene of origin MIRLRT7A3. This was further supported by the induction of miR-let-7a expression upon treatment of HCC cells with a DNA-methyltransferase inhibitor. Using a computational approach, insulin-like growth factor (IGF)-II and IGF-2 mRNA binding proteins (IGF2BP)-2/-3 were identified as potential targets for miR-let-7a that was further confirmed experimentally. Indeed, miR-let-7a mimics diminished IGF-II as well as IGF2BP-2/-3 expression. Direct binding of miR-let-7a to each respective transcript was confirmed using a luciferase reporter assay. In conclusion, this study suggests that DNA hypermethylation leads to epigenetic repression of miR-let-7a in HCC cells, which induces the oncogenic IGF-signaling pathway.

Antiviral Therapy for AECHB and Severe Hepatitis B (Liver Failure)

This chapter describes the principles of antiviral therapy, treatment strategies, medications and recommendations for AECHB, HBV-ACLF, HBV-related liver cirrhosis, HBV-related HCC, and liver transplantation.

Severe exacerbation of chronic hepatitis B is closely related to continuous HBV replication. Therefore, inhibiting HBV replication to reduce viral load may block disease progression and improve the quality of life of these patients. ETV or TDF has been recommend first-line drug for the treatment of AECHB.

A hyperactive immune response due to continuous HBV replication is the main mechanism for development of severe hepatitis B. In addition to comprehensive treatment, early administration of potent nucleoside analogs can rapidly reduce HBV DNA concentration, relieve immune injury induced by HBV, and reduce liver inflammation and patient mortality. Antiviral agents have become important in the treatment of severe exacerbation of chronic hepatitis B.

Long-term antiviral treatment with nucleoside analogs can delay or reverse the progress of liver cirrhosis. Virologic response, viral resistance and adverse drug reactions should be closely monitored during treatment. The treatment should be optimized for maximum effect based on each patient’s responses.

Effective antiviral therapy can suppress HBV replication and reduce the incidence of HBV-related HCC. Patients with HBV-related HCC should receive individualized and optimal multidisciplinary comprehensive treatment. Anti-viral drugs with high efficacy, low resistance and low adverse drug reactions should be selected to improve the patient’s quality of life and prolong survival time.

Methods to prevent HBV reinfection after liver transplantation include passive immunization (HBIG), antiviral treatment (nucleoside analogs) and active immunization (hepatitis B vaccine).

Clinical trials involving sequential combination therapy with NUC and Peg-IFN have shown statistically significant decline in HBsAg levels on treatment and high rates of sustained post-treatment serologic response. Combination therapy with novel DAA and immunotherapeutic approach may hold promise to overcome both cccDNA persistence and immune escape, representing a critical step towards HBV cure.

Retracted Article: MiR-206 reduced the malignancy of hepatocellular carcinoma cells in vitro by inhibiting MET and CTNNB1 gene expressions

The anti-cancer role of miR-206 in hepatocellular carcinoma (HCC) cells has been reported, but its mechanism of action remains poorly understood.

TGFB1-driven mesenchymal stem cell-mediated NIS gene transfer

Based on their excellent tumor-homing capacity, genetically engineered mesenchymal stem cells (MSCs) are under investigation as tumor-selective gene delivery vehicles. Transgenic expression of the sodium iodide symporter (NIS) in genetically engineered MSCs allows noninvasive tracking of MSC homing by imaging of functional NIS expression as well as therapeutic application of 131I. The use of tumor stroma-activated promoters can improve tumor-specific MSC-mediated transgene delivery. The essential role of transforming growth factor B1 (TGFB1) and the SMAD downstream target in the signaling between tumor and the surrounding stroma makes the biology of this pathway a potential option to better control NIS expression within the tumor milieu. Bone marrow-derived MSCs were stably transfected with a NIS-expressing plasmid driven by a synthetic SMAD-responsive promoter (SMAD-NIS-MSCs). Radioiodide uptake assays revealed a 4.9-fold increase in NIS-mediated perchlorate-sensitive iodide uptake in SMAD-NIS-MSCs after TGFB1 stimulation compared to unstimulated cells demonstrating the successful establishment of MSCs, which induce NIS expression in response to activation of TGFB1 signaling using a SMAD-responsive promoter. 123I-scintigraphy revealed significant tumor-specific radioiodide accumulation and thus NIS expression after systemic application of SMAD-NIS-MSCs into mice harboring subcutaneous tumors derived from the human hepatocellular carcinoma (HCC) cell line HuH7, which express TGFB1. 131I therapy in SMAD-NIS-MSCs-treated mice demonstrated a significant delay in tumor growth and prolonged survival. Making use of the tumoral TGFB1 signaling network in the context of MSC-mediated NIS gene delivery is a promising approach to foster tumor stroma-selectivity of NIS transgene expression and tailor NIS-based gene therapy to TGFB1-rich tumor environments.

Immunohistochemical Expression of Epidermal Growth Factor Receptor in Hepatocellular Carcinoma

INTRODUCTION

Epidermal growth factor receptor (EGFR) signaling plays an important role in various cancers, including hepatocellular carcinoma (HCC). We aimed to evaluate immunoexpression of EGFR in HCC and surrounding non-tumor liver tissue and to correlate it to multiple clinicopathologic data.

MATERIAL AND METHODS

We analyzed 60 patients with HCC for multiple clinicopathologic characteristics and survival. Presence of the immunosignal and the percentage of positive tumor cells at the whole tumor tissue sample and adjacent cirrhotic liver tissue were semi-quantitatively determined.

RESULTS

Nineteen patients (31.67%) were female and 41 (68.33%) were male ranging in age from 31 to 85 years, median 61.88±10.51. Mean survival time for female patients was 8.86±1.76 months, for male 13.03±1.50 months and overall survival was 11.6051±1.19 months. The most patients had: T2 status (41.67%), no enlarged lymph nodes (90%), vascular invasion (63.33%) and well differentiated (43.33%) tumors. EGFR immunoexpression was determined in range from 0% to 100% in both tumor and non-tumor tissue with mean value of 39.58% in tumor and 86.86% in cirrhotic tissue (p<0.00). Higher percent of tumor EGFR positive cells were found in cases with higher T status, higher levels of AFP and poorly differentiated carcinoma, but not significantly. Lower percent of tumor EGFR positive cells were found in patients with vascular invasion and enlarged lymph nodes, but also not significantly. EGFR expression in tumor tissue significantly influenced survival of the patients (p<0.05).

CONCLUSION

The study showed that expression of EGFR in lower percentage of tumor cells was associated to favorable prognosis, making it a potential prognostic marker and therapeutic target.

Hepatic growth hormone - JAK2 - STAT5 signalling: Metabolic function, non-alcoholic fatty liver disease and hepatocellular carcinoma progression

The rising prevalence of obesity came along with an increase in associated metabolic disorders in Western countries. Non-alcoholic fatty liver disease (NAFLD) represents the hepatic manifestation of the metabolic syndrome and is linked to primary stages of liver cancer development. Growth hormone (GH) regulates various vital processes such as energy supply and cellular regeneration. In addition, GH regulates various aspects of liver physiology through activating the Janus kinase (JAK) 2- signal transducer and activator of transcription (STAT) 5 pathway. Consequently, disrupted GH - JAK2 - STAT5 signaling in the liver alters hepatic lipid metabolism and is associated with NAFLD development in humans and mouse models. Interestingly, while STAT5 as well as JAK2 deficiency correlates with hepatic lipid accumulation, recent studies suggest that these proteins have unique ambivalent functions in chronic liver disease progression and tumorigenesis. In this review, we focus on the consequences of altered GH - JAK2 - STAT5 signaling for hepatic lipid metabolism and liver cancer development with an emphasis on lessons learned from genetic knockout models.

Small interfering RNA-mediated gene suppression as a therapeutic intervention in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the lethal and difficult-to-cure cancers worldwide. Owing to the late diagnosis and drug resistance of malignant hepatocytes, treatment of this cancer by conventional chemotherapy agents is challenging, and researchers are seeking new alternative treatment options to overcome therapy resistance in this neoplasm. RNA interference (RNAi) is a potent and specific approach in targeting gene expression and has emerged as a novel therapeutic tool for many diseases, including cancers. Small interfering RNA (siRNA) is a type of RNAi that is produced intracellularly from exogenous synthetic oligonucleotides and can selectively knock down target gene expression in a sequence-specific manner. Various factors play roles in the initiation and progression of HCC and provide multiple candidate targets for siRNA intervention. In addition, due to the liver's unique architecture and availability of some hepatic siRNA delivery methods, this organ has received much more attention as a target tissue for such oligonucleotide action. Recent advances in designing nanoparticle systems for the in vivo delivery of siRNAs have markedly enhanced the potency of siRNA-mediated gene silencing under clinical development for HCC therapy. The utility of siRNAs as anti-HCC agents is the subject of the current review. siRNA-based gene therapies could be one of the main feasible approaches for HCC therapy in the future.

Regorafenib: a promising treatment for hepatocellular carcinoma

Introduction: Hepatocellular carcinoma (HCC) is one of the most frequent malignant tumors with 854,000 new cases per year and represents the second most frequent cause of cancer-death. Despite surveillance, the number of patients that are diagnosed at a stage in which they are eligible for curative treatments ranges from 30% to 60%. Advanced HCC (BCLC-C) is characterized by a median survival of 6 months. Sorafenib, the first systemic drug proven to be effective in prolonging survival of unresectable HCC, was approved by the FDA in 2007 but no second-line treatment was available for a decade for patients progressing on sorafenib. Finally, in 2016, the RESORCE trial demonstrated regorafenib as an effective second-line treatment. Areas covered: In this manuscript, the authors review the principal preclinical and clinical trials on regorafenib used in the treatment of unresectable HCC patients progressing on sorafenib and highlight both the advantages and the limitations of this drug. Expert opinion: Regorafenib is the only second-line treatment available for patients progressing on sorafenib. Despite its promising clinical application, many doubts still remain, necessitating further investigation to explore the tolerability of this drug in Child-Pugh B and sorafenib-intolerant patients, while its scarce cost-effectiveness must also be improved.

Low expression of miR-199 in hepatocellular carcinoma contributes to tumor cell hyper-proliferation by negatively suppressing XBP1

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related mortality worldwide, and microRNAs (miRs) are considered to serve important functions in the pathogenesis of HCC by regulating the expression of specific target genes. The present study was conducted to investigate the role of miR-199 and its putative target X-box binding protein 1 (XBP1) in HCC, as well as of the downstream gene cyclin D. The expression levels of miR-199, XBP1 and cyclin D were detected in clinical HCC specimens. The effect of miR-199 on the regulation of HCC cell proliferation and its underlying mechanism were examined in Hep3B2.1–7 cells, through expression assays and measurement of cell proliferation (via Cell Counting Kit-8, and 5-ethynyl-2′-deoxyuridine and DAPI double-staining assays) coupled with gain- and lose- of function experiments. The expression of XBP1 and cyclin D was significantly increased in HCC tissues when compared with adjacent non-HCC tissues, while the expression of miR-199 was decreased. Exogenous miR-199 significantly suppressed the expression of XBP1 and cyclin D in Hep3B2.1–7 cells. However, the expression of XBP1 and cyclin D significantly increased on treatment with miR-199 inhibitor. Consistently, Hep3B2.1–7 cells co-transfected with a wild type reporter plasmid [XBP1-3′untranslated region (UTR)-WT] and exogenous miR-199 exhibited lower relative luciferase enzyme activity than cells co-transfected with negative control miRNA and XBP1-3′UTR-WT, while cells co-transfected with mutated plasmid (XBP1-3′UTR-MU) and miR-199 exhibited no change. It was further observed that knockdown of XBP1 by small interfering RNA significantly decreased the expression of cyclin D in Hep3B2.1–7 cells. Additionally, exogenous miR-199 decreased the proliferation of Hep3B2.1–7 cells, which was contrary to the effect of miR-199 inhibitor. In conclusion, it was demonstrated that miR-199 negatively regulated the expression of XBP1 by directly binding to its 3′UTR and that XBP1 impacted cyclin D expression, which was associated with the cell cycle regulation in Hep3B2.1–7 cells. These findings suggested that a miR-199/XBP1/cyclin D axis may serve an important role in the pathogenesis of HCC.

Heat Stress and Hepatic Laser Thermal Ablation Induce Hepatocellular Carcinoma Growth: Role of PI3K/mTOR/AKT Signaling

Purpose To determine if heat stress and hepatic laser thermal ablation induce hepatocellular carcinoma (HCC) growth and to identify growth factors induced by heat stress. Materials and Methods Non-heat-stressed HCC cells were cocultured with HCC cells or hepatocytes that were heat stressed at 37°C (physiologic), 45°C (moderate), or 50°C (severe) for 10 minutes and proliferation monitored with bioluminescence imaging for up to 6 days after heat stress (three experiments). Rats bearing orthotopic N1S1 HCC were randomly assigned to undergo immediate sham or laser thermal (3 W for 60 or 90 seconds; hereafter, 3W×60s and 3W×90s, respectively) ablation of the median (local) or left (distant) hepatic lobe, and tumor growth was monitored with magnetic resonance imaging for up to 18 days after ablation (six or more rats per group). Experiments were repeated with rats randomly assigned to receive either the adjuvant phosphoinositide 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) inhibitor (NVP-BEZ235) or the vehicle control. Heat-stressed HCC cells and hepatocytes were analyzed by using microarray or quantitative real-time polymerase chain reaction analysis for growth factor expression (three or more experiments). Groups were compared by using one- or two-way analysis of variance, and post hoc pairwise comparison was performed with the Dunnett test. Results There were more non-heat-stressed HCC cells when cells were cocultured with cells subjected to moderate but not physiologic or severe heat stress (P < .001 for both). Local intrahepatic N1S1 tumors were larger at day 18 in the 3W×60s (mean, 3102 mm³ ± 463 [standard error]; P = .004) and 3W×90s (mean, 3538 mm³ ± 667; P < .001) groups than in the sham group (mean, 1363 mm³ ± 361) but not in distant intrahepatic tumors (P = .31). Adjuvant BEZ235 resulted in smaller N1S1 tumors in the BEZ235 and laser thermal ablation group than in the vehicle control and laser thermal ablation group (mean, 1731 mm³ ± 1457 vs 3844 mm³ ± 2400, P < .001). Moderate heat stress induced expression of growth factors in HCC cells and hepatocytes, including heparin-binding growth factor, fibroblast growth factor 21, and nerve growth factor (range, 2.9-66.9-fold; P < .05). Conclusion Moderate heat stress and laser thermal ablation induce hepatocellular carcinoma growth, which is prevented with adjuvant PI3K/mTOR/protein kinase B inhibition.

Prognostic significance of c-Met, β-catenin and FAK in patients with hepatocellular carcinoma following surgery

The present study aimed to investigate the prognostic value of specific molecular markers in patients with hepatocellular carcinoma (HCC) who had received surgery. Immunohistochemical analysis was used to measure the expression of hepatocyte growth factor receptor (c-Met), β-catenin and focal adhesion kinase (FAK) in patients with HCC. c-Met expression was identified to be high in patients with larger tumors, higher α-fetoprotein (AFP) levels, higher Edmondson grades, portal vein invasion and higher tumor-node-metastasis (TNM) stages. FAK expression was high in patients with portal vein invasion, higher Edmondson grades and higher TNM stages. β-catenin expression was high in patients with larger tumors, hepatitis B virus (HBV) infection, portal vein invasion, higher Edmondson grades and higher TNM stages. Following multivariate analysis, FAK (P=0.002) and β-catenin (P=0.006) expression levels were demonstrated to be significantly associated with Edmondson grade. Additionally, the tumor size (P=0.009) and HBV infection status (P=0.002) were revealed to be associated with β-catenin expression. Kaplan-Meier survival curve analysis demonstrated that patients with HCC with higher FAK expression, higher β-catenin expression, portal vein invasion, higher Edmondson grades, higher TNM stages, younger ages and higher AFP levels had significantly poorer prognoses. Cox's regression analysis revealed that the survival period was correlated with the Edmondson grade, age, AFP level, and FAK and β-catenin expression. Univariate analysis of c-Met, β-catenin and FAK identified a significant correlation between FAK and β-catenin (P=0.015). Correlation analysis revealed no significant correlation between the three molecular markers, but β-catenin and c-Met were markedly correlated (P=0.052). No significant correlation between FAK, c-Met or β-catenin expression was identified. FAK and β-catenin expression demonstrated a correlation with a range of clinicopathological factors, and high FAK and β-catenin expression levels were identified to be correlated with a poor survival rate of patients with HCC. Thus, patients with higher FAK and β-catenin expression may require more aggressive therapy. The results of the present study suggest that FAK and β-catenin expression possess more prognostic value than c-Met expression in patients with HCC.

Effects of Peutz-Jeghers syndrome (PJS) causing missense mutations L67P, L182P, G242V and R297S on the structural dynamics of LKB1 (Liver kinase B1) protein

The liver kinase B1 (LKB1) is encoded by LKB1 gene. Several pathogenic mutations of LKB1 causing Peutz-Jeghers syndrome and also cancers in breast, gastric, pancreas, and colon have been reported. The present study is focused to analyze the effects on the structural dynamics of LKB1 caused by the 4 pathogenic missense mutations (L67P, L182P, G242V, and R297S), which are reported to reduce the catalytic activity. In this study, the structural changes of LKB1 in apo- and in heterotrimeric complex (LKB1-STRADα-MO25α) form with wild and mutated LKB1 are investigated using all atomistic molecular dynamic simulation. The present study reveals that these four mutations initiate local structural distortions and the solvent accessibility of the surrounding regions of ATP-binding pocket such as glycine-rich loop, αB and αC loop, activation and catalytic loops. The mutations of L67P, L182P, and G242 V induce distortions of the secondary structure of β1-β3 sheets, π - π interaction (observed between Phe204 of LKB1 and Phe243 of MO25α), and increase the helical properties (both helical twist and length) of the adjacent αH-helix, respectively. The active kinase features like the conformation of catalytic and activation loops, salt bridge and, finally, the formation of stable R- and C-hydrophobic spines are also found to be perturbed by these mutations. Hence, the observed mutation-induced structural distortions fail to coordinate the essential binding nature of LKB1 with STRADα and MO25α, which eventually affects the native function of LKB1. These observations are in line with the experimentally reported reduced kinase activity of LKB1.

Soluble factors from adipose tissue-derived mesenchymal stem cells promote canine hepatocellular carcinoma cell proliferation and invasion

The potential effects of adipose tissue-derived mesenchymal stem cells (AT-MSCs) on the growth and invasion of canine tumours including hepatocellular carcinoma (HCC) are not yet understood. Moreover in humans, the functional contribution of AT-MSCs to malignancies remains controversial. The purpose of this study was to investigate the effects of AT-MSCs on the proliferation and invasion of canine HCC cells in vitro. The effect of AT-MSCs on mRNA levels of factors related to HCC progression were also evaluated. Conditioned medium from AT-MSCs (AT-MSC-CM) significantly enhanced canine HCC cell proliferation and invasion. Moreover, mRNA expression levels of transforming growth factor-beta 1, epidermal growth factor A, hepatocyte growth factor, platelet-derived growth factor-beta, vascular endothelial growth factor, and insulin-like growth factor 2 were 2.3 ± 0.4, 2.0 ± 0.5, 5.7 ± 1.9, 1.7 ± 0.2, 2.1 ± 0.4, and 1.4 ± 0.3 times higher, respectively (P < 0.05). The mRNA expression level of MMP-2 also increased (to 4.0 ± 1.2 times control levels) in canine HCC cells co-cultured with AT-MSCs, but MMP-9 mRNA significantly decreased (to 0.5 ± 0.1 times control levels). These findings suggest that soluble factors from AT-MSCs promote the proliferation and invasion of canine HCC cells.

Effects of Estrogen and Estrogen Receptors on Transcriptomes of HepG2 Cells: A Preliminary Study Using RNA Sequencing

Men have a much higher incidence of hepatocellular carcinoma (HCC), the predominant form of liver cancer, than women, suggesting that estrogens play a protective role in liver cancer development and progression. To begin to understand the potential mechanisms of estrogens' inhibitory effects on HCC development, RNA sequencing was used to generate comprehensive global transcriptome profiles of the human HCC-derived HepG2 cell line following treatment of vehicle (control), estradiol (E2), estrogen receptor alpha- (ERα-) specific agonist 1,3,5-tris(4-hydroxyphenyl)-4-propyl-1H-pyrazole (PPT), or ERβ-specific agonist 2,3-bis(4-hydroxyphenyl)-propionitrile (DPN) using a small set of cells. Gene ontology (GO) analysis identified increased expression of genes involved in the biological process (BP) of response to different stimuli and metabolic processes by E2 and ER agonists, which enhanced molecular function (MF) in various enzyme activities and chemical bindings. Kyoto Encyclopedia of Genes and Genomes (KEGG) functional pathway analysis indicated enhanced pathways associated with carbohydrate metabolism, complement and coagulation cascades, and HIF-1 signaling pathway by E2 and ER agonists. GO analysis also identified decreased expression of genes by E2, PPT, and DPN involved in BP related to the cell cycle and cell division, which reduced MF in activity of multiple enzymes and microtubule activity. KEGG analysis indicated that E2, PPT, and DPN suppressed pathways associated with the cell cycle; E2 and PPT suppressed pathways associated with chemical carcinogenesis and drug metabolism, and DPN suppressed DNA replication, recombination, and repair. Collectively, these differentially expressed genes across HepG2 cell transcriptome involving cellular and metabolic processes by E2 and ER agonists provided mechanistic insight into protective effects of estrogens in HCC development.

Acquisition of Cholangiocarcinoma Traits during Advanced Hepatocellular Carcinoma Development in Mice

Past studies have identified hepatic tumors with mixed hepatocellular carcinoma (HCC) and cholangiocarcinoma (CC) characteristics that have a more aggressive behavior and a poorer prognosis than classic HCC. Whether this pathologic heterogeneity is due to a cell of origin of bipotent liver progenitors or the plasticity of cellular constituents comprising these tumors remains debated. In this study, we investigated the potential acquisition of CC-like traits during advanced development of HCC in mice. Primary and rare high-grade HCC developed in a genetic mouse model. A mouse model of highly efficient HCC invasion and metastasis by orthotopic transplantation of liver cancer organoids propagated from primary tumors in the genetic model was further developed. Invasive/metastatic tumors developed in both models closely recapitulated advanced human HCC and displayed a striking acquisition of CC-related pathologic and molecular features, which was absent in the primary HCC tumors. Our study directly demonstrates the pathologic evolution of HCC during advanced tumor development, providing the first evidence that tumors with mixed HCC and CC features, or at least a subset of these tumors, represent a more advanced developmental stage of HCC. Finally, liver cancer organoid-generated high-grade tumors exhibited significantly increased extracellular vesicle secretion, suggesting that identifying tumor-specific extracellular vesicle proteins in plasma may be a promising tool for liver cancer detection.

Proteinase-Activated Receptor 2 May Drive Cancer Progression by Facilitating TGF-β Signaling

The G protein-coupled receptor proteinase-activated receptor 2 (PAR2) has been implicated in various aspects of cellular physiology including inflammation, obesity and cancer. In cancer, it usually acts as a driver of cancer progression in various tumor types by promoting invasion and metastasis in response to activation by serine proteinases. Recently, we discovered another mode through which PAR2 may enhance tumorigenesis: crosstalk with transforming growth factor-β (TGF-β) signaling to promote TGF-β1-induced cell migration/invasion and invasion-associated gene expression in ductal pancreatic adenocarcinoma (PDAC) cells. In this chapter, we review what is known about the cellular TGF-β responses and signaling pathways affected by PAR2 expression, the signaling activities of PAR2 required for promoting TGF-β signaling, and the potential molecular mechanism(s) that underlie(s) the TGF-β signaling-promoting effect. Since PAR2 is activated through various serine proteinases and biased agonists, it may couple TGF-β signaling to a diverse range of other physiological processes that may or may not predispose cells to cancer development such as local inflammation, systemic coagulation and pathogen infection.

Heat stress induced, ligand-independent MET and EGFR signalling in hepatocellular carcinoma

PURPOSE

The aims of the present study were 2-fold: first, to test the hypothesis that heat stress induces MET and EGFR signalling in hepatocellular carcinoma (HCC) cells and inhibition of this signalling decreases HCC clonogenic survival; and second, to identify signalling pathways associated with heat stress induced MET signalling.

MATERIALS AND METHODS

MET⁺ and EGFR⁺ HCC cells were pre-treated with inhibitors to MET, EGFR, PI3K/mTOR or vehicle and subjected to heat stress or control ± HGF or EGF growth factors and assessed by colony formation assay, Western blotting and/or quantitative mass spectrometry. IACUC approved partial laser thermal or sham ablation was performed on orthotopic N1S1 and AS30D HCC tumours and liver/tumour assessed for phospho-MET and phospho-EGFR immunostaining.

RESULTS

Heat-stress induced rapid MET and EGFR phosphorylation that is distinct from HGF or EGF in HCC cells and thermal ablation induced MET but not EGFR phosphorylation at the HCC tumour ablation margin. Inhibition of the MET and EGFR blocked both heat stress and growth factor induced MET and EGFR phosphorylation and inhibition of MET decreased HCC clonogenic survival following heat stress. Pathway analysis of quantitative phosphoproteomic data identified downstream pathways associated with heat stress induced MET signalling including AKT, ERK, Stat3 and JNK. However, inhibition of heat stress induced MET signalling did not block AKT signalling.

CONCLUSIONS

Heat-stress induced MET and EGFR signalling is distinct from growth factor mediated signalling in HCC cells and MET inhibition enhances heat stress induced HCC cell killing via a PI3K/AKT/mTOR-independent mechanism.

Targeting multiple oncogenic pathways for the treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common forms of liver cancer diagnosed worldwide. HCC occurs due to chronic liver disease and is often diagnosed at advanced stages. Chemotherapeutic agents such as doxorubicin are currently used as first-line agents for HCC therapy, but these are non-selective cytotoxic molecules with significant side effects. Sorafenib, a multi-targeted tyrosine kinase inhibitor, is the only approved targeted drug for HCC patients. However, due to adverse side effects and limited efficacy, there is a need for the identification of novel pharmacological drugs beyond sorafenib. Several agents that target and inhibit various signaling pathways involved in HCC are currently being assessed for HCC treatment. In the present review article, we summarize the diverse signal transduction pathways responsible for initiation as well as progression of HCC and also the potential anticancer effects of selected targeted therapies that can be employed for HCC therapy.

MiR-483-5p promotes IGF-II transcription and is associated with poor prognosis of hepatocellular carcinoma

The human insulin-like growth factor-II (IGF-II) gene transcribes four mRNAs (P1 mRNA-P4 mRNA), and P3 mRNA overexpression contributes to hepatocarcinogenesis. IGF-II-derived miR-483-5p is implicated in the development of cancers. Here, we investigated the involvement of miR-483-5p in P3 mRNA overexpression regulation and its role in hepatocellular carcinoma. Our results showed that miR-483-5p up-regulated P3 mRNA transcription by targeting the 5′-untranslated region (5′UTR) of P3 mRNA in hepatocellular carcinoma. The mechanism was involved in recruiting of an argonaute 1(Ago1)-argonaute 2 (Ago2) complex to the P3 mRNA 5′UTR and the P3 promoter of IGF-II gene by miR-483-5p, accompanied by increased enrichment of RNA polymerase II and activating histone marks histone 3 lysine 4 trimethylation (H3K4me3), histone 3 lysine 27 acetylation (H3K27ac), and histone 4 lysine 5/8/12/16 acetylation (H4Kac) at the P3 promoter. High miR-483-5p expression was an independent predictor for shorter survival of HCC patients. The findings suggest that miR-483-5p promotes P3 mRNA transcription by recruiting the Ago1-Ago2 complex to the P3 mRNA 5′UTR and is associated with poor prognosis of HCC. Our results display a potential new model for miRNAs to up-regulate gene expression.

Therapeutic potential of an anti-angiogenic multimodal biomimetic peptide in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a major cause of cancer-related death worldwide. Due to inadequate screening methods and the common coexistence of limited functional liver reserves, curative treatment options are limited. Liver transplantation is the only curative treatment modality for early HCC. There are multidisciplinary treatment options like ablative treatments, radiation and systemic therapy available for more advanced patients or those that are inoperable. Treatment resistance and progression is inevitable for these HCC patients. Newer therapeutics need to be explored for better management of HCC. HCC is a hypervascular tumor and many pro-angiogenic proteins are found significantly overexpressed in HCC. Here we explored the therapeutic potential of the anti-angiogenic, anti-lymphangiogenic, and directly anti-tumorigenic biomimetic collagen IV-derived peptide developed by our group. Human HCC cell lines HuH7, Hep3b and HepG2 showed significant disruption of cell adhesion and migration upon treatment with the peptide. Consistent with previously described multimodal inhibitory properties, the peptide was found to inhibit both c-Met and IGF1R signaling in HepG2 cells and blocked HepG2 conditioned media stimulation of microvascular endothelial cell (MEC) tube formation. Furthermore, the peptide treatment of mouse HepG2 tumor xenografts significantly inhibited growth relative to untreated controls. The peptide was also found to improve the survival of autochthonous Myc-induced HCC in a transgenic mouse model. Mechanistically, we found that the peptide treatment reduced microvascular density in the autochthonous liver tumors with increased apoptosis. This study shows the promising therapeutic potential of our biomimetic peptide in the treatment of HCC.

Serum and tissue markers in hepatocellular carcinoma and cholangiocarcinoma: clinical and prognostic implications

HCC represents the sixth most common cancer worldwide and the second leading cause of cancer-related death. Despite the high incidence, treatment options for advanced HCC remain limited and unsuccessful, resulting in a poor prognosis. Despite the major advances achieved in the diagnostic management of HCC, only one third of the newly diagnosed patients are presently eligible for curative treatments. Advances in technology and an increased understanding of HCC biology have led to the discovery of novel biomarkers. Improving our knowledge about serum and tissutal markers could ultimately lead to an early diagnosis and better and early treatment strategies for this deadly disease. Serum biomarkers are striking potential tools for surveillance and early diagnosis of HCC thanks to the non-invasive, objective, and reproducible assessments they potentially enable. To date, many biomarkers have been proposed in the diagnosis of HCC. Cholangiocarcinoma (CCA) is an aggressive malignancy, characterized by early lymph node involvement and distant metastasis, with 5-year survival rates of 5%-10%. The identification of new biomarkers with diagnostic, prognostic or predictive value is especially important as resection (by surgery or combined with a liver transplant) has shown promising results and novel therapies are emerging. However, the relatively low incidence of CCA, high frequency of co-existing cholestasis or cholangitis (primary sclerosing cholangitis –PSC- above all), and difficulties with obtaining adequate samples, despite advances in sampling techniques and in endoscopic visualization of the bile ducts, have complicated the search for accurate biomarkers. In this review, we attempt to analyze the existing literature on this argument.

Aberrantly activated Cox-2 and Wnt signaling interact to maintain cancer stem cells in glioblastoma

Glioblastoma recurrence after aggressive therapy typically occurs within six months, and patients inevitably succumb to their disease. Tumor recurrence is driven by a subpopulation of cancer stem cells in glioblastoma (glioblastoma stem-like cells, GSCs), which exhibit resistance to cytotoxic therapies, compared to their non-stem-cell counterparts. Here, we show that the Cox-2 and Wnt signaling pathways are aberrantly activated in GSCs and interact to maintain the cancer stem cell identity. Cox-2 stimulates GSC self-renewal and proliferation through prostaglandin E2 (PGE2), which in turn activates the Wnt signaling pathway. Wnt signaling underlies PGE2-induced GSC self-renewal and independently directs GSC self-renewal and proliferation. Inhibition of PGE2 enhances the effect of temozolomide on GSCs, but affords only a modest survival advantage in a xenograft model in the setting of COX-independent Wnt activation. Our findings uncover an aberrant positive feedback interaction between the Cox-2/PGE2 and Wnt pathways that mediates the stem-like state in glioblastoma.