Lack of gp130 expression in hepatocytes attenuates tumor progression in the DEN model

Chitosan-based biomaterial delivery strategies for hepatocellular carcinoma

Background

Hepatocellular carcinoma accounts for 80% of primary liver cancers, is the most common primary liver malignancy. Hepatocellular carcinoma is the third leading cause of tumor-related deaths worldwide, with a 5-year survival rate of approximately 18%. Chemotherapy, although commonly used for hepatocellular carcinoma treatment, is limited by systemic toxicity and drug resistance. Improving targeted delivery of chemotherapy drugs to tumor cells without causing systemic side effects is a current research focus. Chitosan, a biopolymer derived from chitin, possesses good biocompatibility and biodegradability, making it suitable for drug delivery. Enhanced chitosan formulations retain the anti-tumor properties while improving stability. Chitosan-based biomaterials promote hepatocellular carcinoma apoptosis, exhibit antioxidant and anti-inflammatory effects, inhibit tumor angiogenesis, and improve extracellular matrix remodeling for enhanced anti-tumor therapy.

Methods

We summarized published experimental papers by querying them.

Results and Conclusions

This review discusses the physicochemical properties of chitosan, its application in hepatocellular carcinoma treatment, and the challenges faced by chitosan-based biomaterials.

The double-edged effects of IL-6 in liver regeneration, aging, inflammation, and diseases

Interleukin-6 (IL-6) is a pleiotropic cytokine and exerts its complex biological functions mainly through three different signal modes, called cis-, trans-, and cluster signaling. When IL-6 binds to its membrane or soluble receptors, the co-receptor gp130 is activated to initiate downstream signaling and induce the expression of target genes. In the liver, IL-6 can perform its anti-inflammatory activities to promote hepatocyte reprogramming and liver regeneration. On the contrary, IL-6 also exerts the pro-inflammatory functions to induce liver aging, fibrosis, steatosis, and carcinogenesis. However, understanding the roles and underlying mechanisms of IL-6 in liver physiological and pathological processes is still an ongoing process. So far, therapeutic agents against IL‑6, IL‑6 receptor (IL‑6R), IL-6-sIL-6R complex, or IL-6 downstream signal transducers have been developed, and determined to be effective in the intervention of inflammatory diseases and cancers. In this review, we summarized and highlighted the understanding of the double-edged effects of IL-6 in liver homeostasis, aging, inflammation, and chronic diseases, for better shifting the "negative" functions of IL-6 to the "beneficial" actions, and further discussed the potential therapeutic effects of targeting IL-6 signaling in the clinics.

Impaired degradation of YAP1 and IL6ST by chaperone-mediated autophagy promotes proliferation and migration of normal and hepatocellular carcinoma cells

Impaired degradation of the transcriptional coactivator YAP1 and IL6ST (interleukin 6 cytokine family signal transducer), two proteins deregulated in liver cancer, has been shown to promote tumor growth. Here, we demonstrate that YAP1 and IL6ST are novel substrates of chaperone-mediated autophagy (CMA) in human hepatocellular carcinoma (HCC) and hepatocyte cell lines. Knockdown of the lysosomal CMA receptor LAMP2A increases protein levels of YAP1 and IL6ST, without changes in mRNA expression. Additionally, both proteins show KFERQ-dependent binding to the CMA chaperone HSPA8 and accumulate into isolated lysosomes after stimulation of CMA by prolonged starvation. We further show that LAMP2A downregulation promotes the proliferation and migration in HCC cells and a human hepatocyte cell line, and that it does so in a YAP1- and IL6ST-dependent manner. Finally, LAMP2A expression is downregulated, and YAP1 and IL6ST expression is upregulated, in human HCC biopsies. Taken together, our work reveals a novel mechanism that controls the turnover of two cancer-relevant proteins and suggests a tumor suppressor function of CMA in the liver, advocating for the exploitation of CMA activity for diagnostic and therapeutic purposes.Abbreviations: ACTB: actin beta; ATG5: autophagy related 5; ATG7: autophagy related 7; CMA: chaperone-mediated autophagy; eMI: endosomal microautophagy; HCC: hepatocellular carcinoma; HSPA8: heat shock protein family A (Hsp70) member 8; IL6ST: interleukin 6 cytokine family signal transducer; JAK: Janus kinase; LAMP1: lysosomal associated membrane protein 1; LAMP2A: lysosomal associated membrane protein 2A; MAPK8: mitogen-activated protein kinase 8; P6: pyridine 6; SQSTM1: sequestosome 1; TUBA: tubulin alpha; VDAC1: voltage dependent anion channel 1; VP: verteporfin; YAP1: Yes1 associated transcriptional regulator.

Targeting the gp130_D5 domain through pharmacophore modelling and structure-based virtual screening using natural plant products: A detailed molecular dynamics study for development of novel anti-cancer therapeutics

An overexpression and upregulation has been observed in the activity of LIF in various cancers which leads to the worsening prognosis of numerous patients. Domain D5 of gp130 forms a crucial part of the downstream signalling pathway necessary for the activity of this cytokine. Due to the absence of any known inhibitors or previous studies conducted on this domain, this domain presents itself as a novel potential therapeutic target for the development of anti-cancer drugs. Here, an attempt has been made to discover one such potential lead drug candidate via the application of various computer-aided drug designing techniques. A natural plant products library was used along with known inhibitors of the STAT3 signalling pathway through which LIF exerts its activity. The ligand displaying the highest interaction with the target, a good docking score, and an optimal bioavailability was chosen. This ligand- ZINC02131250 forms a very strong complex with the target domain thatremains stable throughout the simulation period. Binding of the ligand to the target also results in an overall decrease in the domain's flexibility, free energy, and motion. Thus, this ligand can be taken for further testing using bioassays and then be used as a viable novel treatment for many cancer types.

Oncostatin M: From Intracellular Signaling to Therapeutic Targets in Liver Cancer

Primary liver cancers represent the third-most-common cause of cancer-related mortality worldwide, with an incidence of 80-90% for hepatocellular carcinoma (HCC) and 10-15% for cholangiocarcinoma (CCA), and an increasing morbidity and mortality rate. Although HCC and CCA originate from independent cell populations (hepatocytes and biliary epithelial cells, respectively), they develop in chronically inflamed livers. Evidence obtained in the last decade has revealed a role for cytokines of the IL-6 family in the development of primary liver cancers. These cytokines operate through the receptor subunit gp130 and the downstream Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathways. Oncostatin M (OSM), a member of the IL-6 family, plays a significant role in inflammation, autoimmunity, and cancer, including liver tumors. Although, in recent years, therapeutic approaches for the treatment of HCC and CCA have been implemented, limited treatment options with marginal clinical benefits are available. We discuss how OSM-related pathways can be selectively inhibited and therapeutically exploited for the treatment of liver malignancies.

Pleiotropic, Unique and Shared Responses Elicited by IL-6 Family Cytokines in Human Vascular Endothelial Cells

Vascular endothelial cells express glycoprotein 130 (gp130), which is utilized as a signaling receptor by cytokines in the interleukin-6 (IL-6) family. Several IL-6 family cytokines can be found in the circulatory system during physiological or pathological conditions, and may influence endothelial function and response. This study evaluated and compared the cellular and molecular responses induced by IL-6 family cytokines in human endothelial cells. A proteomic analysis showed that IL-6 family cytokines induce the release of a range of proteins from endothelial cells, such as C-C motif chemokine ligand 23, hepatocyte growth factor, and IL-6. Pathway analysis indicated that gp130-signaling in endothelial cells regulates several functions related to angiogenesis and immune cell recruitment. The present investigation also disclosed differences and similarities between different IL-6 family cytokines in their ability to induce protein release and regulate gene expression and intracellular signaling, in regards to which oncostatin M showed the most pronounced effect. Further, this study showed that soluble gp130 preferentially blocks trans-signaling-induced responses, but does not affect responses induced by classic signaling. In conclusion, IL-6 family cytokines induce both specific and overlapping molecular responses in endothelial cells, and regulate genes and proteins involved in angiogenesis and immune cell recruitment.

The Role of Cytokines in the Different Stages of Hepatocellular Carcinoma

Simple Summary

Non-homeostatic cytokine expression during hepatocellular carcinogenesis, together with simple and inexpensive cytokine detection techniques, has opened up its use as potential biomarkers, from cancer detection to prognosis. However, carcinogenic programs during cancer progression are not linear. Therefore, cytokines with prognostic potential in one stage may not be relevant in another. Here, we reviewed cytokines with clinical potential in different settings during hepatocellular carcinoma progression.

Abstract

Hepatocellular carcinoma (HCC) is the primary form of liver cancer and a leading cause of cancer-related death worldwide. Early detection remains the most effective strategy in HCC management. However, the spectrum of underlying liver diseases preceding HCC, its genetic complexity, and the lack of symptomatology in early stages challenge early detection. Regardless of underlying etiology, unresolved chronic inflammation is a common denominator in HCC. Hence, many inflammatory molecules, including cytokines, have been investigated as potential biomarkers to predict different stages of HCC. Soluble cytokines carry cell-signaling functions and are easy to detect in the bloodstream. However, its biomarkers’ role remains limited due to the dysregulation of immune parameters related to the primary liver process and their ability to differentiate carcinogenesis from the underlying disease. In this review, we discuss and provide insight on cytokines with clinical relevance for HCC differentiating those implicated in tumor formation, early detection, advanced disease, and response to therapy.

The two facets of gp130 signalling in liver tumorigenesis

The liver is a vital organ with multiple functions and a large regenerative capacity. Tumours of the liver are the second most frequently cause of cancer-related death and develop in chronically inflamed livers. IL-6-type cytokines are mediators of inflammation and almost all members signal via the receptor subunit gp130 and the downstream signalling molecule STAT3. We here summarize current knowledge on how gp130 signalling and STAT3 in tumour cells and cells of the tumour micro-environment drives hepatic tumorigenesis. We furthermore discuss very recent findings describing also anti-tumorigenic roles of gp130/STAT3 and important considerations for therapeutic interventions.

A comprehensive review on anticancer mechanism of bazedoxifene

Cancer is counted as a second leading cause of death among nontransmissible diseases. Identification of novel anticancer drugs is therefore necessary for the effective treatment of cancer. Conventional drug discovery is time consuming and expensive process. Unlike conventional drug discovery, drug repositioning offers a novel strategy for urgent drug discovery since it is a cost-effective and faster process. Bazedoxifene (BZA) is a synthetic selective estrogen receptor modulator, approved by the United States Food and Drug Administration for the treatment of osteoporosis in postmenopausal women. BZA is now being studied for its anticancer activity in various cancers including breast cancer, liver cancer, pancreatic cancer, colon cancer, head and neck cancer, medulloblastoma, brain cancer, and gastrointestinal cancer. Studies have reported that BZA is effective in reducing cancer progression through multiple mechanisms. BZA could effectively inhibit STAT3, PI3K/AKT, and MAPK signaling pathways and induce apoptosis. In addition to its anticancer activity as monotherapy, BZA has been shown to enhance the chemotherapeutic efficacy of clinical drugs such as paclitaxel, cisplatin, palbociclib, and oxaliplatin in multiple neoplasms. This review mainly focused on the anticancer activity, cellular targets, and anticancer mechanism of BZA, which may help the further design and conduct of research and repositioning it for oncological clinic trials.

Down-regulation of GP130 signaling sensitizes bladder cancer to cisplatin by impairing Ku70 DNA repair signaling and promoting apoptosis

Chemoresistance is one of the barriers for the development of bladder cancer treatments. Previously, we showed that glycoprotein-130 (GP130) is overexpressed in chemoresistant bladder cancer cells and that knocking down GP130 expression reduced cell viability. In our current work, we showed that down-regulation of GP130 sensitized bladder cancer cells to cisplatin-based chemotherapy by activating DNA repair signaling. We performed immunohistochemistry and demonstrated a positive correlation between the levels of Ku70, an initiator of canonical non-homologous end joining repair (c-NHEJ) and suppressor of apoptosis, and GP130 in human bladder cancer specimens. GP130 knockdown by SC144, a small molecule inhibitor, in combination with cisplatin, increased the number of DNA lesions, specifically DNA double-stranded breaks, with a subsequent increase in apoptosis and reduced cell viability. Furthermore, GP130 inhibition attenuated Ku70 expression in bladder and breast cancer cells as well as in transformed kidney cells. In addition, we fabricated a novel polymer-lipid hybrid delivery system to facilitate GP130 siRNA delivery that had a similar efficiency when compared with Lipofectamine, but induced less toxicity.

MyD88-dependent signaling in non-parenchymal cells promotes liver carcinogenesis

In Western countries, a rising incidence of obesity and type 2 diabetes correlates with an increase of non-alcoholic steatohepatitis (NASH)-a major risk factor for liver cirrhosis and hepatocellular carcinoma (HCC). NASH is associated with chronic liver injury, triggering hepatocyte death and enhanced translocation of intestinal bacteria, leading to persistent liver inflammation through activation of Toll-like receptors and their adapter protein myeloid differentiation factor 88 (MyD88). Therefore, we investigated the role of MyD88 during progression from NASH to HCC using a mouse model of chronic liver injury (hepatocyte-specific deletion of nuclear factor κB essential modulator, Nemo; NemoΔhepa). NemoΔhepa; NemoΔhepa/MyD88-/- and NemoΔhepa/MyD88Δhepa were generated and the impact on liver disease progression was investigated. Ubiquitous MyD88 ablation (NemoΔhepa/MyD88-/-) aggravated the degree of liver damage, accompanied by an overall decrease in inflammation, whereas infiltrating macrophages and natural killer cells were elevated. At a later stage, MyD88 deficiency impaired HCC formation. In contrast, hepatocyte-specific MyD88 deletion (NemoΔhepa/MyD88Δhepa) did not affect disease progression. These results suggest that signaling of Toll-like receptors through MyD88 in non-parenchymal liver cells is required for carcinogenesis during chronic liver injury. Hence, blocking MyD88 signaling may offer a therapeutic option to prevent HCC formation in patients with NASH.

Jak-Stat Signaling Induced by Interleukin-6 Family Cytokines in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide. It can be caused by chronic liver cell injury with resulting sustained inflammation, e.g., triggered by infections with hepatitis viruses B (HBV) and C (HCV). Death of hepatocytes leads to the activation of compensatory mechanisms, which can ultimately result in liver fibrosis and cirrhosis. Another common feature is the infiltration of the liver with inflammatory cells, which secrete cytokines and chemokines that act directly on the hepatocytes. Among several secreted proteins, members of the interleukin-6 (IL-6) family of cytokines have emerged as important regulatory proteins that might constitute an attractive target for therapeutic intervention. The IL-6-type cytokines activate multiple intracellular signaling pathways, and especially the Jak/STAT cascade has been shown to be crucial for HCC development. In this review, we give an overview about HCC pathogenesis with respect to IL-6-type cytokines and the Jak/STAT pathway. We highlight the role of mutations in genes encoding several proteins involved in the cytokine/Jak/STAT axis and summarize current knowledge about IL-6 family cytokines in this context. We further discuss possible anti-cytokine therapies for HCC patients in comparison to already established therapies.

Modulation of the IL-6-Signaling Pathway in Liver Cells by miRNAs Targeting gp130, JAK1, and/or STAT3

Interleukin-6 (IL-6)-type cytokines share the common receptor glycoprotein 130 (gp130), which activates a signaling cascade involving Janus kinases (JAKs) and signal transducer and activator of transcription (STAT) transcription factors. IL-6 and/or its signaling pathway is often deregulated in diseases, such as chronic liver diseases and cancer. Thus, the identification of compounds inhibiting this pathway is of interest for future targeted therapies. We established novel cellular screening systems based on a STAT-responsive reporter gene (Cypridina luciferase). Of a library containing 538 microRNA (miRNA) mimics, several miRNAs affected hyper-IL-6-induced luciferase activities. When focusing on candidate miRNAs specifically targeting 3′ UTRs of signaling molecules of this pathway, we identified, e.g., miR-3677-5p as a novel miRNA affecting protein expression of both STAT3 and JAK1, whereas miR-16-1-3p, miR-4473, and miR-520f-3p reduced gp130 surface expression. Interestingly, combination treatment with 2 or 3 miRNAs targeting gp130 or different signaling molecules of the pathway did not increase the inhibitory effects on phospho-STAT3 levels and STAT3 target gene expression compared to treatment with single mimics. Taken together, we identified a set of miRNAs of potential therapeutic value for cancer and inflammatory diseases, which directly target the expression of molecules within the IL-6-signaling pathway and can dampen inflammatory signal transduction.

Bazedoxifene exhibits growth suppressive activity by targeting interleukin-6/glycoprotein 130/signal transducer and activator of transcription 3 signaling in hepatocellular carcinoma

The interleukin (IL)‐6/glycoprotein (GP)130/signal transducer and activator of transcription (STAT)3 pathway is emerging as a target for the treatment of hepatocellular carcinoma. IL‐6 binds to IL‐6R, forming a binary complex, which further combines with GP130 to transduce extracellular signaling by activating STAT3. Therefore, blocking the interaction between IL‐6 and GP130 may inhibit the IL‐6/GP130/STAT3 signaling pathway and its biological effects. It has been reported that bazedoxifene acetate (BAZ), a selective estrogen receptor modulator approved by the US Food and Drug Administration, could inhibit IL‐6/GP130 protein‐protein interactions. Western blot, immunofluorescence staining, wound healing and colony formation assays were used to detect the effect of BAZ on liver cancer cells. Cell viability was evaluated by MTT assay. Apoptosis of cells was determined using the Annexin V‐FITC detection kit. Mouse xenograft tumor models were utilized to evaluate the effect of BAZ in vivo. Our data showed that BAZ inhibited STAT3 phosphorylation (P‐STAT3) and expression of STAT3 downstream genes, inducing apoptosis in liver cancer cells. BAZ inhibited P‐STAT3 induced by IL‐6, but not by leukemia inhibitory factor. BAZ inhibited P‐STAT1 and P‐STAT6 less significantly as elicited by interferon‐α, interferon‐γ and IL‐4. In addition, pretreatment of BAZ impeded the translocation of STAT3 to nuclei induced by IL‐6. BAZ inhibited cell viability, wound healing and colony formation in vitro. Furthermore, tumor growth in HEPG2 mouse xenografts were significantly inhibited by daily intragastric gavage of BAZ. Our results suggest that BAZ inhibited the growth of hepatocellular carcinoma in vitro and in vivo, indicating another potential strategy for HCC prevention and therapy.

Obesity-Induced TNFα and IL-6 Signaling: The Missing Link between Obesity and Inflammation-Driven Liver and Colorectal Cancers

Obesity promotes the development of numerous cancers, such as liver and colorectal cancers, which is at least partly due to obesity-induced, chronic, low-grade inflammation. In particular, the recruitment and activation of immune cell subsets in the white adipose tissue systemically increase proinflammatory cytokines, such as tumor necrosis factor α (TNFα) and interleukin-6 (IL-6). These proinflammatory cytokines not only impair insulin action in metabolic tissues, but also favor cancer development. Here, we review the current state of knowledge on how obesity affects inflammatory TNFα and IL-6 signaling in hepatocellular carcinoma and colorectal cancers.

Chitosan-coated liposomes loaded with butyric acid demonstrate anticancer and anti-inflammatory activity in human hepatoma HepG2 cells

Butyric acid (BA) has been reported to induce anticancer effects on hepatocellular carcinoma (HCC) cells both in vitro and in vivo. However, its delivery and release in cancer tissues must be optimized. On the basis of these requirements, we prepared liposomes coated with chitosan and uncoated liposomes and both types were loaded with BA through a thin-film hydration method. The liposomes coated or uncoated with chitosan had a mean hydrodynamic size of 83.5 and 110.3 nm, respectively, with a homogeneous size distribution of the particles. For evaluation of the biological effects of the nanoformulations, the hepatoblastoma (HB) HepG2 cell line was utilized. BA-loaded liposomes coated with chitosan showed a considerable higher cytotoxicity than both uncoated liposomes and free BA, with IC50 values, after 72 h of incubation, of 7.5, 2.5 and 1.6 mM, respectively. Treatment of HepG2 cells for 5 h with the BA-loaded liposomes coated with chitosan at 5 mM lowered the extent of the increase in IL-8, IL-6, TNF-α and TGF-β expression of approximately 64, 58, 85 and 73.8%, respectively, when compared to the untreated cells. The BA-loaded liposomes coated with chitosan had marked capacity to be internalized in human HB cells showing an increased cytotoxic activity when compared with free BA and important anti-inflammatory effects by inhibiting production of cytokines with a central role in liver cell survival.

IL-6 and IL-8 Serum Levels Predict Tumor Response and Overall Survival after TACE for Primary and Secondary Hepatic Malignancies

While surgical resection represents the standard potentially curative therapy for liver cancer, transarterial chemoembolization (TACE) has evolved as a standard therapy for intermediate-stage hepatocellular carcinoma (HCC) as well as liver metastases. However, it is still not fully understood which patients particularly benefit from TACE. Cytokines represent a broad category of signaling molecules that might reflect concomitant inflammation as an adverse prognostic factor. Here, we evaluated the role of interleukin (IL)-6, IL-8, and CC-chemokine ligand (CCL)22 as biomarkers in the context of TACE treatment. Cytokine serum levels were analyzed by multiplex immunoassay in 54 patients (HCC: n = 44, liver metastases: n = 10) undergoing TACE as well as 51 healthy controls. Patients with primary and secondary liver cancer showed significantly elevated levels of IL-6 and IL-8 but not CCL22 compared to healthy controls. Interestingly, low pre-interventional levels of IL-6 and IL-8 were predictors for an objective response after TACE in binary logistic regression. In contrast, patients with high pre-interventional IL-6 and IL-8 serum levels not only poorly responded to TACE but had a significantly impaired overall survival. Serum levels of IL-6 and IL-8 represent promising biomarkers for patients undergoing TACE and might help to pre-interventionally identify patients who particularly benefit from TACE regarding objective treatment response and overall survival.

Interleukin-6: A promising cytokine to support liver regeneration and adaptive immunity in liver pathologies

Liver pathologies (fibrosis, cirrhosis, alcoholic, non-alcoholic diseases and hepatocellular carcinoma) represent one of the most common causes of death worldwide. A number of genetic and environmental factors contribute to the development of liver diseases. Interleukin-6 (IL-6) is a pleiotropic cytokine, exerting variety of effects on inflammation, liver regeneration, and defence against infections by regulating adaptive immunity. Due to its high abundance in inflammatory settings, IL-6 is often viewed as a detrimental cytokine. However, accumulating evidence supports the view that IL-6 has a beneficial impact in numerous liver pathologies, due to its roles in liver regeneration and in promoting an anti-inflammatory response in certain conditions. IL-6 promotes proliferation, angiogenesis and metabolism, and downregulates apoptosis and oxidative stress; together these functions are critical for mediating hepatoprotection. IL-6 is also an important regulator of adaptive immunity where it induces T cell differentiation and regulates autoimmunity. It can augment antiviral adaptive immune responses and mitigate exhaustion of T cells during chronic infection. This review focuses on studies that present IL-6 as a key factor in regulating liver regeneration and in supporting effector immune functions and suggests that these functions of IL-6 can be exploited in treatment strategies for liver pathologies.

Transforming growth factor-β in liver cancer stem cells and regeneration

Cancer stem cells have established mechanisms that contribute to tumor heterogeneity as well as resistance to therapy. Over 40% of hepatocellular carcinomas (HCCs) are considered to be clonal and arise from a stem-like/cancer stem cell. Moreover, HCC is the second leading cause of cancer death worldwide, and an improved understanding of cancer stem cells and targeting these in this cancer are urgently needed. Multiple studies have revealed etiological patterns and multiple genes/pathways signifying initiation and progression of HCC; however, unlike the transforming growth factor β (TGF-β) pathway, loss of p53 and/or activation of β-catenin do not spontaneously drive HCC in animal models. Despite many advances in cancer genetics that include identifying the dominant role of TGF-β signaling in gastrointestinal cancers, we have not reached an integrated view of genetic mutations, copy number changes, driver pathways, and animal models that support effective targeted therapies for these common and lethal cancers. Moreover, pathways involved in stem cell transformation into gastrointestinal cancers remain largely undefined. Identifying the key mechanisms and developing models that reflect the human disease can lead to effective new treatment strategies. In this review, we dissect the evidence obtained from mouse and human liver regeneration, and mouse genetics, to provide insight into the role of TGF-β in regulating the cancer stem cell niche. (Hepatology Communications 2017;1:477-493).

IL6-mediated inflammatory loop reprograms normal to epithelial-mesenchymal transition+ metastatic cancer stem cells in preneoplastic liver of transforming growth factor beta-deficient β2-spectrin+/- mice

Hepatocellular carcinoma (HCC) is the second-leading cause of cancer-related deaths worldwide with a poor survival rate. As many as 40% of HCCs are clonal, with alteration of key tumor-suppressor pathways in stem cells as the primary cause of HCC initiation. However, mechanisms that generate metastatic stem cells in preneoplastic liver tissue are not well understood. We hypothesized that chronic inflammation is a major driver of the transformation of genetically defective liver stem cells (LSCs) into highly metastatic liver cancer cells in premalignant liver tissue. We developed models of chronic inflammation in wild-type (WT) and β2-spectrin (β2SP)^+/- (SPTBN1) mice. CD133⁺ LSCs derived from preneoplastic livers of β2SP^+/- mice treated with interleukin-6 (pIL6; ^IL6 β2SP^+/- LSCs) were highly tumorigenic and metastatic, whereas those derived from WT mice treated with pIL6 (^IL6 WT LSCs) had significantly less proliferation and no tumorigenic properties. ^IL6 β2SP^+/- LSCs not only exhibited nuclear localization of Twist and Slug, markers of epithelial-mesenchymal transition (EMT), but also constitutive activation of nuclear factor kappa B (NFκB; RELA). Knockdown of NFκB decreased the EMT phenotypes and metastatic capacity of these cells. NFκB in ^IL6 β2SP^+/- LSCs was activated by transforming growth factor β (TGFβ)-activated kinase 1 (TAK1; MAP3K7), which is associated with poor survival in HCC and interleukin-6 (IL6) expression. The amount of constitutively activated NFκB increased dramatically from normal to cirrhotic to HCC tissues from human patients.

CONCLUSION

IL6-mediated inflammation programs constitutive activation of the TAK1-NFκB signaling cascade in CD133⁺ LSCs, and this program interacts with deficient TGFβ signaling, thereby accelerating the transformation of normal LSCs to metastatic cancer stem cells (mCSCs). Indeed, this study delineates the development of EMT-positive mCSCs in HCC-free liver tissue upon chronic inflammation. (Hepatology 2017;65:1222-1236).

A cell-autonomous tumour suppressor role of RAF1 in hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is a leading cause of cancer deaths, but its molecular heterogeneity hampers the design of targeted therapies. Currently, the only therapeutic option for advanced HCC is Sorafenib, an inhibitor whose targets include RAF. Unexpectedly, RAF1 expression is reduced in human HCC samples. Modelling RAF1 downregulation by RNAi increases the proliferation of human HCC lines in xenografts and in culture; furthermore, RAF1 ablation promotes chemical hepatocarcinogenesis and the proliferation of cultured (pre)malignant mouse hepatocytes. The phenotypes depend on increased YAP1 expression and STAT3 activation, observed in cultured RAF1-deficient cells, in HCC xenografts, and in autochthonous liver tumours. Thus RAF1, although essential for the development of skin and lung tumours, is a negative regulator of hepatocarcinogenesis. This unexpected finding highlights the contribution of the cellular/tissue environment in determining the function of a protein, and underscores the importance of understanding the molecular context of a disease to inform therapy design.

The kinase RAF1 usually exerts pro-tumorigenic functions promoting proliferation in RAS-driven cancers. Here, the authors using a mouse model of HCC and clinical data describe an unexpected oncosuppressor role of RAF1 in hepatocarcinoma development linked to a gp130-dependent Stat3 activation and YAP1 regulation.

Cytokine Regulation of Metastasis and Tumorigenicity

The human body combats infection and promotes wound healing through the remarkable process of inflammation. Inflammation is characterized by the recruitment of stromal cell activity including recruitment of immune cells and induction of angiogenesis. These cellular processes are regulated by a class of soluble molecules called cytokines. Based on function, cell target, and structure, cytokines are subdivided into several classes including: interleukins, chemokines, and lymphokines. While cytokines regulate normal physiological processes, chronic deregulation of cytokine expression and activity contributes to cancer in many ways. Gene polymorphisms of all types of cytokines are associated with risk of disease development. Deregulation RNA and protein expression of interleukins, chemokines, and lymphokines have been detected in many solid tumors and hematopoetic malignancies, correlating with poor patient prognosis. The current body of literature suggests that in some tumor types, interleukins and chemokines work against the human body by signaling to cancer cells and remodeling the local microenvironment to support the growth, survival, and invasion of primary tumors and enhance metastatic colonization. Some lymphokines are downregulated to suppress tumor progression by enhancing cytotoxic T cell activity and inhibiting tumor cell survival. In this review, we will describe the structure/function of several cytokine families and review our current understanding on the roles and mechanisms of cytokines in tumor progression. In addition, we will also discuss strategies for exploiting the expression and activity of cytokines in therapeutic intervention.

IL-6 pathway in the liver: From physiopathology to therapy

Interleukin 6 (IL-6) is a pleiotropic four-helix-bundle cytokine that exerts multiple functions in the body. In the liver, IL-6 is an important inducer of the acute phase response and infection defense. IL-6 is furthermore crucial for hepatocyte homeostasis and is a potent hepatocyte mitogen. It is not only implicated in liver regeneration, but also in metabolic function of the liver. However, persistent activation of the IL-6 signaling pathway is detrimental to the liver and might ultimately result in the development of liver tumors. On target cells IL-6 can bind to the signal transducing subunit gp130 either in complex with the membrane-bound or with the soluble IL-6 receptor to induce intracellular signaling. In this review we describe how these different pathways are involved in the physiology and pathophyiology of the liver. We furthermore discuss how IL-6 pathways can be selectively inhibited and therapeutically exploited for the treatment of liver pathologies.

Recombinant soluble gp130 protein reduces DEN-induced primary hepatocellular carcinoma in mice

IL-6 (interleukin 6) plays an important role in the development and growth of hepatocellular carcinoma (HCC) via both classic signaling and trans-signaling pathways. Soluble gp130 (sgp130) is known to be a natural inhibitor of the trans-signaling pathway. In the present study, our goal was to investigate whether recombinant sgp130 could suppress the initiation and progression of HCC in mouse models. Our results demonstrate that sgp130 induced an apoptosis of HepG2 cells and inhibited the clonogenicity of HepG2 in vitro. Moreover, the IL-6 trans-signaling pathway is significantly suppressed by sgp130 as reflected by the decrease in the level of STAT3 phosphorylation and other inflammatory factors both in vitro and in vivo. In the DEN-induced HCC mouse model, intravenous injection of sgp130 attenuated hepatic fibrosis at 16 weeks and reduced the initiation and progression of primary HCC at 36 weeks. Furthermore, our results also demonstrate that intravenous administration of sgp130 significantly suppressed the growth and metastasis of xenograft human HCC in NOD/SCID mice.