Disruption of transforming growth factor-beta signaling through beta-spectrin ELF leads to hepatocellular cancer through cyclin D1 activation

Tea domain transcription factor TEAD4 mitigates TGF-β signaling and hepatocellular carcinoma progression independently of YAP

Tea domain transcription factor 4 (TEAD4) plays a pivotal role in tissue development and homeostasis by interacting with Yes-associated protein (YAP) in response to Hippo signaling inactivation. TEAD4 and YAP can also cooperate with transforming growth factor-β (TGF-β)-activated Smad proteins to regulate gene transcription. Yet, it remains unclear whether TEAD4 plays a YAP-independent role in TGF-β signaling. Here, we unveil a novel tumor suppressive function of TEAD4 in liver cancer via mitigating TGF-β signaling. Ectopic TEAD4 inhibited TGF-β-induced signal transduction, Smad transcriptional activity, and target gene transcription, consequently suppressing hepatocellular carcinoma cell proliferation and migration in vitro and xenograft tumor growth in mice. Consistently, depletion of endogenous TEAD4 by siRNAs enhanced TGF-β signaling in cancer cells. Mechanistically, TEAD4 associates with receptor-regulated Smads (Smad2/3) and Smad4 in the nucleus, thereby impairing the binding of Smad2/3 to the histone acetyltransferase p300. Intriguingly, these negative effects of TEAD4 on TGF-β/Smad signaling are independent of YAP, as impairing the TEAD4-YAP interaction through point mutagenesis or depletion of YAP and/or its paralog TAZ has little effect. Together, these results unravel a novel function of TEAD4 in fine tuning TGF-β signaling and liver cancer progression in a YAP-independent manner.

HCV and tumor-initiating stem-like cells

Neoplasms contain tumor-initiating stem-like cells (TICs) that are characterized by increased drug resistance. The incidence of many cancer types have trended downward except for few cancer types, including hepatocellular carcinoma (HCC). Therefore mechanism of HCC development and therapy resistance needs to be understood. These multiple hits by hepatitis C virus (HCV) eventually promotes transformation and TIC genesis, leading to HCC development. This review article describes links between HCV-associated HCC and TICs. This review discusses 1) how HCV promotes genesis of TICs and HCC development; 2) how this process avails itself as a novel therapeutic target for HCC treatment; and 3) ten hall marks of TIC oncogenesis and HCC development as targets for novel therapeutic modalities.

Coordinated activation of TGF-β and BMP pathways promotes autophagy and limits liver injury after acetaminophen intoxication

Ligands of the transforming growth factor-β (TGF-β) superfamily, including TGF-βs, activins, and bone morphogenetic proteins (BMPs), have been implicated in hepatic development, homeostasis, and pathophysiology. We explored the mechanisms by which hepatocytes decode and integrate injury-induced signaling from TGF-βs and activins (TGF-β/Activin) and BMPs. We mapped the spatiotemporal patterns of pathway activation during liver injury induced by acetaminophen (APAP) in dual reporter mice carrying a fluorescent reporter of TGF-β/Activin signaling and a fluorescent reporter of BMP signaling. APAP intoxication induced the expression of both reporters in a zone of cells near areas of tissue damage, which showed an increase in autophagy and demarcated the borders between healthy and injured tissues. Inhibition of TGF-β superfamily signaling by overexpressing the inhibitor Smad7 exacerbated acute liver histopathology but eventually accelerated tissue recovery. Transcriptomic analysis identified autophagy as a process stimulated by TGF-β1 and BMP4 in hepatocytes, with Trp53inp2, which encodes a rate-limiting factor for autophagy initiation, as the most highly induced autophagy-related gene. Collectively, these findings illustrate the functional interconnectivity of the TGF-β superfamily signaling system, implicate the coordinated activation of TGF-β/Activin and BMP pathways in balancing tissue reparatory and regenerative processes upon APAP-induced hepatotoxicity, and highlight opportunities and potential risks associated with targeting this signaling system for treating hepatic diseases.

The Bright and the Dark Side of TGF-β Signaling in Hepatocellular Carcinoma: Mechanisms, Dysregulation, and Therapeutic Implications

Simple Summary

Transforming growth factor β (TGF-β) signaling is a preeminent regulator of diverse cellular and physiological processes. Frequent dysregulation of TGF-β signaling has been implicated in cancer. In hepatocellular carcinoma (HCC), the most prevalent form of primary liver cancer, the autocrine and paracrine effects of TGF-β have paradoxical implications. While acting as a potent tumor suppressor pathway in the early stages of malignancy, TGF-β diverts to a promoter of tumor progression in the late stages, reflecting its bright and dark natures, respectively. Within this context, targeting TGF-β represents a promising therapeutic option for HCC treatment. We discuss here the molecular properties of TGF-β signaling in HCC, attempting to provide an overview of its effects on tumor cells and the stroma. We also seek to evaluate the dysregulation mechanisms that mediate the functional switch of TGF-β from a tumor suppressor to a pro-tumorigenic signal. Finally, we reconcile its biphasic nature with the therapeutic implications.

Abstract

Hepatocellular carcinoma (HCC) is associated with genetic and nongenetic aberrations that impact multiple genes and pathways, including the frequently dysregulated transforming growth factor β (TGF-β) signaling pathway. The regulatory cytokine TGF-β and its signaling effectors govern a broad spectrum of spatiotemporally regulated molecular and cellular responses, yet paradoxically have dual and opposing roles in HCC progression. In the early stages of tumorigenesis, TGF-β signaling enforces profound tumor-suppressive effects, primarily by inducing cell cycle arrest, cellular senescence, autophagy, and apoptosis. However, as the tumor advances in malignant progression, TGF-β functionally switches to a pro-tumorigenic signal, eliciting aggressive tumor traits, such as epithelial–mesenchymal transition, tumor microenvironment remodeling, and immune evasion of cancer cells. On this account, the inhibition of TGF-β signaling is recognized as a promising therapeutic strategy for advanced HCC. In this review, we evaluate the functions and mechanisms of TGF-β signaling and relate its complex and pleiotropic biology to HCC pathophysiology, attempting to provide a detailed perspective on the molecular determinants underlying its functional diversion. We also address the therapeutic implications of the dichotomous nature of TGF-β signaling and highlight the rationale for targeting this pathway for HCC treatment, alone or in combination with other agents.

Identification of Growth Factors, Cytokines and Mediators Regulated by Artemisia annua L. Polyphenols (pKAL) in HCT116 Colorectal Cancer Cells: TGF-β1 and NGF-β Attenuate pKAL-Induced Anticancer Effects via NF-κB p65 Upregulation

The anticancer effects of natural phytochemicals are relevant to the modulation of cytokine signaling pathways in various cancer cells with stem-like properties as well as immune cells. The aim of this study was to elucidate a novel anticancer mechanism of Artemisia annua L. polyphenols (pKAL) involved in the regulation of growth factors, cytokines and mediators in stem-like HCT116 colorectal cancer cells. Through RayBiotech human L-1000 antibody array and bioinformatics analysis, we show here that pKAL-induced anticancer effects are associated with downregulation of growth factor and cytokine signaling proteins including TGFA, FGF16, PDGFC, CCL28, CXCR3, IRF6 and SMAD1. Notably, we found that TGF-β signaling proteins such as GDF10, ENG and TGFBR2 and well-known survival proteins such as NGF-β, VEGFD and insulin were significantly upregulated by pKAL. Moreover, the results of hematoxylin staining, cell viability assay and Western blot analysis demonstrated that TGF-β1 and NGF-β attenuated pKAL-induced anticancer effects by inhibiting pKAL-induced downregulation of caspase-8, NF-κB p65 and cyclin D1. These results suggest that certain survival mediators may be activated by pKAL through the TGF-β1 and NGF-β signaling pathways during pKAL-induced cell death and thus, strategies to inhibit the survival signaling are inevitably required for more effective anticancer effects of pKAL.

Loss of SPTBN1 Suppresses Autophagy Via SETD7-mediated YAP Methylation in Hepatocellular Carcinoma Initiation and Development

BACKGROUND & AIMS

Loss of Spectrin beta, non-erythrocytic 1 (SPTBN1) plays an important role in the carcinogenesis of hepatocellular carcinoma (HCC); however, the mechanisms underlying its involvement remain poorly understood. Defects in autophagy contribute to hepatic tumor formation. Hence, in this study, we explored the role and mechanism of SPTBN1 in the autophagy of hepatic stem cells (HSCs) and HCC cells.

METHODS

Expansion, autophagy, and malignant transformation of HSCs were detected in the injured liver of Sptbn1^+/- mice induced by 3,5-diethoxycarbonyl-1,4-dihydrocollidine treatment. Hippo pathway and Yes-associated protein (YAP) stabilization were examined in isolated HSCs, Huh-7, and PLC/PRF/5 HCC cells and hepatocytes with or without loss of SPTBN1.

RESULTS

We found that heterozygous SPTBN1 knockout accelerated liver tumor development with 3,5-diethoxycarbonyl-1,4-dihydrocollidine induction. Rapamycin promoted autophagy in murine HSCs and reversed the increased malignant transformation induced by heterozygous SPTBN1 deletion. Loss of SPTBN1 also decreased autophagy and increased YAP stability and nuclear localization in human HCC cells and tissues, whereas YAP inhibition attenuated the effects of SPTBN1 deficiency on autophagy. Finally, we found that SPTBN1 positively regulated the expression of suppressor of variegation 3-9-enhancer of zeste-trithorax domain containing lysine methyltransferase 7 to promote YAP methylation, which may lead to YAP degradation and inactivation.

CONCLUSIONS

Our findings provide the first demonstration that loss of SPTBN1 impairs autophagy of HSCs to promote expansion and malignant transformation during hepatocarcinogenesis. SPTBN1 also cooperates with suppressor of variegation 3-9-enhancer of zeste-trithorax domain containing lysine methyltransferase 7 to inactive YAP, resulting in enhanced autophagy of HCC cells. These results may open new avenues targeting SPTBN1 for the prevention and treatment of HCC.

Systematic Analysis of Cytostatic TGF-Beta Response in Mesenchymal-Like Hepatocellular Carcinoma Cell Lines

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most challenging malignancies, with high morbidity and mortality rates. The transforming growth factor-β (TGF-β) pathway plays a dual role in HCC, acting as both tumor suppressor and promoter. A thorough understanding of the mechanisms underlying its opposing functions is important. The growth suppressive effects of TGF-β remain largely unknown for mesenchymal HCC cells. Using a systematic approach, here we assess the cytostatic TGF-β responses and intracellular transduction of the canonical TGF-β/Smad signaling cascade in mesenchymal-like HCC cell lines.

METHODS

Nine mesenchymal-like HCC cell lines, including SNU182, SNU387, SNU398, SNU423, SNU449, SNU475, Mahlavu, Focus, and Sk-Hep1, were used in this study. The cytostatic effects of TGF-β were evaluated by cell cycle analysis, BrdU labeling, and SA-β-Gal assay. RT-PCR and western blot analysis were utilized to determine the mRNA and protein expression levels of TGF-β signaling components and cytostatic genes. Immunoperoxidase staining and luciferase reporter assays were performed to comprehend the transduction of the canonical TGF-β pathway.

RESULTS

We report that mesenchymal-like HCC cell lines are resistant to TGF-β-induced growth suppression. The vast majority of cell lines have an active canonical signaling from the cell membrane to the nucleus. Three cell lines had lost the expression of cytostatic effector genes.

CONCLUSION

Our findings reveal that cytostatic TGF-β responses have been selectively lost in mesenchymal-like HCC cell lines. Notably, their lack of responsiveness was not associated with a widespread impairment of TGF-β signaling cascade. These cell lines may serve as valuable models for studying the molecular mechanisms underlying the loss of TGF-β-mediated cytostasis during hepatocarcinogenesis.

SPTBN1 inhibits inflammatory responses and hepatocarcinogenesis via the stabilization of SOCS1 and downregulation of p65 in hepatocellular carcinoma

Background: Spectrin, beta, non-erythrocytic 1 (SPTBN1), an adapter protein for transforming growth factor beta (TGF-β) signaling, is recognized as a tumor suppressor in the development of hepatocellular carcinoma (HCC); however, the underlying molecular mechanisms of this tumor suppression remain obscure.

Methods: The effects on expression of pro-inflammatory cytokines upon the inhibition or impairment of SPTBN1 in HCC cell lines and liver tissues of Sptbn1^+/- and wild-type (WT) mice were assessed by analyses of quantitative real-time reverse-transcription polymerase chain reaction (QRT-PCR), enzyme linked immunosorbent assay (ELISA), Western blotting and gene array databases from HCC patients. We investigated the detailed molecular mechanisms underlying the inflammatory responses by immunoprecipitation-Western blotting, luciferase reporter assay, chromatin immunoprecipitation quantitative real time PCR (ChIP-qPCR), immunohistochemistry (IHC) and electrophoretic mobility shift assay (EMSA). The proportion of myeloid-derived suppressor cells in liver, spleen, bone marrow and peripheral blood samples from WT and Sptbn1^+/- mice were measured by fluorescence-activated cell sorting (FACS) analysis. Further, the hepatocacinogenesis and its correlation with inflammatory microenvironment by loss of SPTBN1/SOCS1 and induction of p65 were analyzed by treating WT and Sptbn1^+/- mice with 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC).

Results: Loss of SPTBN1 in HCC cells upregulated the expression of pro-inflammatory cytokines including interleukin-1α (IL-1α), IL-1β, and IL-6, and enhanced NF-κB transcriptional activation. Mechanistic analyses revealed that knockdown of SPTBN1 by siRNA downregulated the expression of suppressor of cytokine signaling 1 (SOCS1), an E3 ligase of p65, and subsequently upregulated p65 accumulation in the nucleus of HCC cells. Restoration of SOCS1 abrogated this SPTBN1 loss-associated elevation of p65 in HCC cells. In human HCC tissues, SPTBN1 gene expression was inversely correlated with gene expression of IL-1α, IL-1β and IL-6. Furthermore, a decrease in the levels of SPTBN1 gene, as well as an increase in the gene expression of IL-1β or IL-6 predicted shorter relapse free survival in HCC patients, and that HCC patients with low expression of SPTBN1 or SOCS1 protein is associated with poor survival. Heterozygous loss of SPTBN1 (Sptbn1^+/-) in mice markedly upregulated hepatic expression of IL-1α, IL-1β and IL-6, and elevated the proportion of myeloid-derived suppressor cells (MDSCs) and CD4⁺CD25⁺Foxp3⁺ regulatory T cells (Foxp3⁺Treg) cells in the liver, promoting hepatocarcinogenesis of mouse fed by DDC.

Conclusions: Our findings provided evidence that loss of SPTBN1 in HCC cells increases p65 protein stability via the inhibition of SOCS1 and enhances NF-κB activation, stimulating the release of inflammatory cytokines, which are critical molecular mechanisms for the loss of SPTBN1-induced liver cancer formation. Reduced SPTBN1 and SOCS1 predict poor outcome in HCC patients.

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.

CircATRNL1 activates Smad4 signaling to inhibit angiogenesis and ovarian cancer metastasis via miR-378

Ovarian cancer is one of the most frequent carcinomas in females, and the occurrence rate is still rising despite many advances made. The pathogenesis of ovarian cancer remains greatly unclear. Here, we investigated the mechanisms of ovarian cancer, with the focus on circATRNL1. Human ovarian cancer tissues and cell lines were used to examine levels of circATRNL1, miR‐378, Smad4, AKT, and other proliferation‐related and migration‐related proteins. Cellular assays were used to determine cancer cell proliferation, invasion, migration, apoptosis, and angiogenesis. We validated the interactions of circATRNL1/miR‐378 and miR‐378/Smad4, and a mouse tumor xenograft model was employed to assess the effect of circATRNL1 on tumor growth and metastasis in vivo. We found that circATRNL1 was decreased while miR‐378 was increased in human ovarian cancer tissues and cells. circATRNL1 bound to miR‐378 while miR‐378 directly targeted Smad4. Overexpression of circATRNL1 or knockdown of miR‐378 suppressed angiogenesis and ovarian cancer cell proliferation, invasion, and migration via decreasing proliferation‐ and migration‐related proteins via miR‐378 or Smad4, respectively. Overexpression of circATRNL1 restrained ovarian cancer growth and abdominal metastasis in vivo. Our findings indicate that circATRNL1 acts as a miR‐378 sponge to active Smad4 signaling and suppresses angiogenesis and ovarian cancer metastasis.

βII spectrin (SPTBN1): biological function and clinical potential in cancer and other diseases

βII spectrin, the most common isoform of non-erythrocyte spectrin, is a cytoskeleton protein present in all nucleated cells. Interestingly, βII spectrin is essential for the development of various organs such as nerve, epithelium, inner ear, liver and heart. The functions of βII spectrin include not only establishing and maintaining the cell structure but also regulating a variety of cellular functions, such as cell apoptosis, cell adhesion, cell spreading and cell cycle regulation. Notably, βII spectrin dysfunction is associated with embryonic lethality and the DNA damage response. More recently, the detection of altered βII spectrin expression in tumors indicated that βII spectrin might be involved in the development and progression of cancer. Its mutations and disorders could result in developmental disabilities and various diseases. The versatile roles of βII spectrin in disease have been examined in an increasing number of studies; nonetheless, the exact mechanisms of βII spectrin are still poorly understood. Thus, we summarize the structural features and biological roles of βII spectrin and discuss its molecular mechanisms and functions in development, homeostasis, regeneration and differentiation. This review highlight the potential effects of βII spectrin dysfunction in cancer and other diseases, outstanding questions for the future investigation of therapeutic targets. The investigation of the regulatory mechanism of βII spectrin signal inactivation and recovery may bring hope for future therapy of related diseases.

The dichotomous role of TGF-β in controlling liver cancer cell survival and proliferation

Hepatocellular carcinoma (HCC) is the major form of primary liver cancer and one of the most prevalent and life-threatening malignancies globally. One of the hallmarks in HCC is the sustained cell survival and proliferative signals, which are determined by the balance between oncogenes and tumor suppressors. Transforming growth factor beta (TGF-β) is an effective growth inhibitor of epithelial cells including hepatocytes, through induction of cell cycle arrest, apoptosis, cellular senescence, or autophagy. The antitumorigenic effects of TGF-β are bypassed during liver tumorigenesis via multiple mechanisms. Furthermore, along with malignant progression, TGF-β switches to promote cancer cell survival and proliferation. This dichotomous nature of TGF-β is one of the barriers to therapeutic targeting in liver cancer. Thereafter, understanding the underlying molecular mechanisms is a prerequisite for discovering novel antitumor drugs that may specifically disable the growth-promoting branch of TGF-β signaling or restore its tumor-suppressive arm. This review summarizes how TGF-β inhibits or promotes liver cancer cell survival and proliferation, highlighting the functional switch mechanisms during the process.

miR-296-5p inhibits IL-1β-induced apoptosis and cartilage degradation in human chondrocytes by directly targeting TGF-β1/CTGF/p38MAPK pathway

Osteoarthritis (OA) is characterized by apoptosis of chondrocytes and an imbalance of extracellular matrix (ECM) synthesis and catabolism. Emerging evidence has demonstrated that miRNAs are involved in OA pathologies, but the role of miR-296-5p in OA remains unclear. The present study proposes to reveal the functions and mechanisms of miR-296-5p in a cell model of OA. In this study, human chondrocytes were treated with 5 ml interleukin-1 beta (IL-1β) to induce apoptosis and cartilage degradation. Our results showed that miR-296-5p was downregulated in chondrocytes stimulated with IL-1β. Overexpressed miR-296-5p enhanced cell proliferation and inhibited apoptosis and matrix degrading enzyme expression in response to IL-1β stimulation, and knockdown of miR-296-5p showed the opposite effect. Further, we found that miR-296-5p directly targeted the 3'-untranslated region (3'-UTR) of TGF-β1 mRNA, and miR-296-5p inactivated the TGF-β1/CTGF/p38MAPK signaling pathway. Overexpression of TGF-β1 alleviated the inhibition of miR-296-5p on chondrocyte apoptosis and cartilage degradation. In conclusion, miR-296-5p inhibited the progression of OA through the CTGF/p38MAPK pathway by directly targeting TGF-β1.

The CoV-2 outbreak: how hematologists could help to fight Covid-19

COVID-19 is a medical emergency, with 20 % of patients presenting with severe clinical manifestations. From the pathogenetic point of view, COVID-19 mimics two other well-known diseases characterized by cytokine storm and hyper-activation of the immune response, with consequent organ damage: acute graft-versus-host disease (aGVHD) and macrophage activation syndrome (MAS). Hematologists are confident with these situations requiring a prompt therapeutic approach for switching off the uncontrolled cytokine release; here, we discuss pros and cons of drugs that are already employed in hematology in the light of their possible application in COVID-19. The most promising drugs might be: Ruxolitinib, a JAK1/2 inhibitor, with a rapid and powerful anti-cytokine effect, tyrosine kinase inhibitors (TKIs), with their good anti-inflammatory properties, and perhaps the anti-Cd26 antibody Begelomab. We also present immunological data from gene expression experiments where TKIs resulted effective anti-inflammatory and pro-immune drugs. A possible combined treatment algorithm for COVID-19 is here proposed.

Cell fate, metabolic reprogramming and lncRNA of tumor-initiating stem-like cells induced by alcohol

Alcoholism synergizes the development of the hepatocellular carcinoma (HCC) in patients infected with hepatitis B or C virus (HBV or HCV). Tumor-initiating stem-like cells (TICs) are refractory to therapy and have expression of stemness transcription factors. Leaky-gut-derived endotoxin stimulates TLR4-NANOG pathway that skews asymmetric cell division and that metabolically reprograms hepatocytes/liver progenitor cells, leading to self-renewal. TICs isolated from mouse HCC models or human HCCs are tumorigenic and have p53 degradation via phosphorylation of the protective protein NUMB and its dissociation from p53 by the oncofetal protein TBC1D15. Furthermore, dysregulation of lncRNA promotes genesis of TICs, leading to HCC development. This review describes roles of cell fate decision, metabolic reprogramming and lncRNA for TIC genesis and liver oncogenesis. This project was supported by NIH grants 1R01AA018857-01, 5R21AA025470, P50AA11999 (Animal Core, Morphology Core, and Pilot Project Program), R24AA012885 (Non-Parenchymal Liver Cell Core) and pilot project funding (5P30DK048522-13).

Contextual Regulation of TGF-β Signaling in Liver Cancer

Primary liver cancer is one of the leading causes for cancer-related death worldwide. Transforming growth factor beta (TGF-β) is a pleiotropic cytokine that signals through membrane receptors and intracellular Smad proteins, which enter the nucleus upon receptor activation and act as transcription factors. TGF-β inhibits liver tumorigenesis in the early stage by inducing cytostasis and apoptosis, but promotes malignant progression in more advanced stages by enhancing cancer cell survival, EMT, migration, invasion and finally metastasis. Understanding the molecular mechanisms underpinning the multi-faceted roles of TGF-β in liver cancer has become a persistent pursuit during the last two decades. Contextual regulation fine-tunes the robustness, duration and plasticity of TGF-β signaling, yielding versatile albeit specific responses. This involves multiple feedback and feed-forward regulatory loops and also the interplay between Smad signaling and non-Smad pathways. This review summarizes the known regulatory mechanisms of TGF-β signaling in liver cancer, and how they channel, skew and even switch the actions of TGF-β during cancer progression.

SPTBN1 and cancer, which links?

SPTBN1 is a dynamic intracellular nonpleckstrin homology-domain protein, functioning as a transforming growth factor-β signal transducing adapter protein which is necessary to form Smad3/Smad4 complex. Recently SPTBN1 is considered to be associated with many kinds of cancers. SPTBN1 expression and function differ between different tumor states or types. This review summarizes the recent advances in the expression patterns of SPTBN1 in cancers, and in understanding the mechanisms by which SPTBN1 affects the occurrence, progression, and metastasis of cancer. Identifying SPTBN1 expression and function in cancers will contribute to the clinical diagnosis and treatment of cancer and the investigation of anticancer drugs.

NANOG-Dependent Metabolic Reprogramming and Symmetric Division in Tumor-Initiating Stem-like Cells

Alcohol abuse synergistically heightens the development of the third most deadliest cancer hepatocellular carcinoma (HCC) in patients infected with hepatitis C virus (HCV). Ectopically expressed TLR4 promotes liver tumorigenesis in alcohol-fed HCV Ns5a or Core transgenic mice. CD133+/CD49f + tumor-initiating stem cell-like cells (TICs) isolated from these models are tumorigenic have p53 degradation via phosphorylation of the protective protein NUMB and its dissociation from p53 by the oncoprotein TBC1D15. Nutrient deprivation reduces overexpressed TBC1D15 in TICs via autophagy-mediated degradation, suggesting a possible role of this oncoprotein in linking metabolic reprogramming and self-renewal.

Baishouwu Extract Suppresses the Development of Hepatocellular Carcinoma via TLR4/MyD88/NF-κB Pathway

Purpose: The root of Cynanchum auriculatum Royle ex Wight, known as Baishouwu, has been widely used for a tonic supplement since ancient times. The current study was performed to explore the effect of Baishouwu extract on the development of experimental hepatocellular carcinoma (HCC) and the potential mechanism involved.

Methods: Rats were injected diethylnitrosamine (DEN) to initiate the multistep hepatocarcinogenesis. Animals were treated concurrently with Baishouwu extract given daily by oral gavage for 20 weeks to evaluate its protective effects. Time series sera and organ samples from each group were collected to evaluate the effect of Baishouwu extract on hepatic carcinogenesis.

Results: It was found that Baishouwu extract pretreatment successfully attenuated liver injury induced by DEN, as shown by decreased levels of serum biochemical indicators (AST, ALT, ALP, TP, and T-BIL). Administration of Baishouwu extract inhibited the fibrosis-related index in serum and live tissue, respectively from inflammation stage to HCC stage after DEN treatment. It significantly reduced the incidence and multiplicity of DEN-induced HCC development in a dose-dependent manner. Macroscopic and microscopic features suggested that pretreatment with Baishouwu extract for 20 weeks was effective in inhibiting DEN-induced inflammation, liver fibrosis, and HCC. Furthermore, TLR4 overexpression induced by DEN was decreased by Baishouwu extract, leading to the markedly down-regulated levels of MyD88, TRAF6, NF-κB p65, TGF-β1 and α-SMA in hepatitis, cirrhosis, and hepatocarcinoma.

Conclusion: In conclusion, Baishouwu extract exhibited potent effect on the development of HCC by altering TLR4/MyD88/ NF-κB signaling pathway in the sequence of hepatic inflammation-fibrosis-cancer, which provided novel insights into the mechanism of Baishouwu extract as a candidate for the pretreatment of HCC in the future.

A Transforming Growth Factor-β and H19 Signaling Axis in Tumor-Initiating Hepatocytes That Regulates Hepatic Carcinogenesis

Functions of transforming growth factor-β (TGF-β) in the liver vary depending on specific cell types and their temporal response to TGF-β during different stages of hepatocarcinogenesis (HCG). Through analysis of tumor tissues from hepatocellular carcinoma (HCC) patients, we were able to cluster hepatic epithelial cell-derived TGF-β gene signatures in association with distinct clinical prognoses. To delineate the role of hepatic epithelial TGF-β signaling in HCC development, we used an experimental system in which tumor-initiating hepatocytes (TICs) were isolated from TGF-β receptor II floxed mice (Tgfbr2^fl/fl ) and transplanted into syngeneic C57BL/6J mice by splenic injection. Recipient mice were then administered Cre-expressing adenovirus (Ad-Cre) to inactivate Tgfbr2 in transplanted TICs. After latency, Tgfbr2-inactivated TICs formed larger and more tumor nodules in recipient livers compared to TICs without Tgfbr2 inactivation. In vitro analyses revealed that treatment of cultured TICs with TGF-β inhibited expression of progenitor cell factors (including SRY (sex determining region Y)-box 2 [Sox2]). RNA sequencing (RNA-seq) analysis identified H19 as one of the most up-regulated long noncoding RNA (lncRNA) in association with Tgfbr2 inactivation in TICs. Tgfbr2 inactivation by Ad-Cre led to a 5-fold increase of H19 expression in TICs. Accordingly, TGF-β treatment reduced H19 expression. We observed that forced overexpression of Sox2 in TICs increased transcription of H19, whereas knockdown of Sox2 decreased it. Furthermore, depletion of H19 reduced the progenitor property of TICs in vitro and decreased their tumorigenic potential in vivo. Finally, we observed a low level of H19 mRNA expression in human HCC tissues from patients with the epithelial TGF-β gene signature in association with favorable prognosis. Conclusion: Our findings describe a TGF-β and H19 signaling axis by Sox2 in TICs that importantly regulates HCG.

Utilization of spectrins βI and βIII in diagnosis of hepatocellular carcinoma

Spectrins are a group of cytoskeletal proteins which participate in many important cellular functions. It has been suggested that loss of spectrin isoforms may be associated with tumorigenesis of lymphoma, leukemia, gastric cancer and hepatocellular carcinoma (HCC). We recently reported that βI spectrin expression was present in normal hepatocytes but lost in HCC cells, which suggested that spectrins may be helpful markers in diagnosis of HCC. In this study, using immunohistochemical staining, we further investigated the expression pattern of four spectrin isoforms (αII, βI-III) on different benign and malignant liver tumors including focal nodular hyperplasia (FNH), hepatic adenoma (HA), HCC, and cholangiocarcinoma (CC). The results revealed that βI spectrin was moderately to strongly positive in FNH and HA tissues, but was only weakly positive or lost in HCC cases and was weakly positive in all CC cases. In addition, the βIII spectrin, majority of which was moderately positive in both FNH and HA tissues, was mostly lost in poorly differentiated HCC but remained at least moderately positive in most CC cases. These results suggest that spectrins βI and βIII may be used to differentiate well differentiated HCC from FNH or HA, and poorly differentiated HCC from CC, respectively.

Opposing roles and potential antagonistic mechanism between TGF-β and BMP pathways: Implications for cancer progression

The transforming growth factor β (TGF-β) superfamily participates in tumour proliferation, apoptosis, differentiation, migration, invasion, immune evasion and extracellular matrix remodelling. Genetic deficiency in distinct components of TGF-β and BMP-induced signalling pathways or their excessive activation has been reported to regulate the development and progression of some cancers. As more in-depth studies about this superfamily have been conducted, more evidence suggests that the TGF-β and BMP pathways play an opposing role. The cross-talk of these 2 pathways has been widely studied in kidney disease and bone formation, and the opposing effects have also been observed in some cancers. However, the antagonistic mechanisms are still insufficiently investigated in cancer. In this review, we aim to display more evidences and possible mechanisms accounting for the antagonism between these 2 pathways, which might provide some clues for further study in cancer.

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Describe the basics of TGF-β and BMP signalling

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Summarize the potential mechanisms accounting for the antagonism between TGF-β and BMP pathways

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Provide some evidence about the antagonistic effects between pathways observed in some cancers

Transforming Growth Factor-β-Induced Cell Plasticity in Liver Fibrosis and Hepatocarcinogenesis

The Transforming Growth Factor-beta (TGF-β) family plays relevant roles in the regulation of different cellular processes that are essential for tissue and organ homeostasis. In the case of the liver, TGF-β signaling participates in different stages of disease progression, from initial liver injury toward fibrosis, cirrhosis and cancer. When a chronic injury takes place, mobilization of lymphocytes and other inflammatory cells occur, thus setting the stage for persistence of an inflammatory response. Macrophages produce profibrotic mediators, among them, TGF-β, which is responsible for activation -transdifferentiation- of quiescent hepatic stellate cells (HSC) to a myofibroblast (MFB) phenotype. MFBs are the principal source of extracellular matrix protein (ECM) accumulation and prominent mediators of fibrogenesis. TGF-β also mediates an epithelial-mesenchymal transition (EMT) process in hepatocytes that may contribute, directly or indirectly, to increase the MFB population. In hepatocarcinogenesis, TGF-β plays a dual role, behaving as a suppressor factor at early stages, but contributing to later tumor progression, once cells escape from its cytostatic effects. As part of its potential pro-tumorigenic actions, TGF-β induces EMT in liver tumor cells, which increases its pro-migratory and invasive potential. In parallel, TGF-β also induces changes in tumor cell plasticity, conferring properties of a migratory tumor initiating cell (TIC). The main aim of this review is to shed light about the pleiotropic actions of TGF-β that explain its effects on the different liver cell populations. The cross-talk with other signaling pathways that contribute to TGF-β effects, in particular the Epidermal Growth Factor Receptor (EGFR), will be presented. Finally, we will discuss the rationale for targeting the TGF-β pathway in liver pathologies.

Transforming growth factor-β1 and lysophosphatidic acid activate integrin β6 gene promoter in Hep-3B cells

Although it is difficult to detect αvβ6 integrin (αvβ6) in normal epithelia cells, its expression is upregulated during wound healing and carcinogenesis. Overexpression of αvβ6 has been demonstrated in epithelial cell carcinomas, such as adenocarcinoma of the colon and ovary. However, the expression of αvβ6 has not been reported in hepatocellular carcinoma (HCC). We previously indicated that LPA may induce αvβ6-mediated TGF-β1 signaling mechanisms during the pathogenesis of lung injury and fibrosis. In addition, transforming growth factor-β1 (TGF-β1) and lysophosphatidic acid (LPA) have been demonstrated to participate in the progression of HCC. In the present study, we hypothesized that TGF-β1 and LPA would serve a key role in the subunit integrin β6 (Itgβ6) transcriptional regulatory mechanism in HCC. It was identified that human HCC tissues and Hep-3B cells expressed Itgβ6. Treatment of Hep-3B with TGF-β1 or LPA increased the expression of Itgβ6. Furthermore, truncation experiments indicated a positive regulatory region at -326 to -157 bp of the Itgβ6 promoter. TGF-β1 and LPA increased transcriptional activation at this regulatory region. To the best of our knowledge, the present study was the first to demonstrate Itgβ6 expression in HCC, and the data indicate that TGF-β1 and LPA regulate Itgβ6 expression through the Itgβ6 gene promoter, which is an important factor in the development of HCC.

αII-spectrin and βII-spectrin do not affect TGFβ1-induced myofibroblast differentiation

Mechanosensing of fibroblasts plays a key role in the development of fibrosis. So far, no effective treatments are available to treat this devastating disorder. Spectrins regulate cell morphology and are potential mechanosensors in a variety of non-erythroid cells, but little is known about the role of spectrins in fibroblasts. We investigate whether αII- and βII-spectrin are required for the phenotypic properties of adult human dermal (myo)fibroblasts. Knockdown of αII- or βII-spectrin in fibroblasts did not affect cell adhesion, cell size and YAP nuclear/cytosolic localization. We further investigated whether αII- and βII-spectrin play a role in the phenotypical switch from fibroblasts to myofibroblasts under the influence of the pro-fibrotic cytokine TGFβ1. Knockdown of spectrins did not affect myofibroblast formation, nor did we observe changes in the organization of αSMA stress fibers. Focal adhesion assembly was unaffected by spectrin deficiency, as was collagen type I mRNA expression and protein deposition. Wound closure was unaffected as well, showing that important functional properties of myofibroblasts are unchanged without αII- or βII-spectrin. In fact, fibroblasts stimulated with TGFβ1 demonstrated significantly lower endogenous mRNA levels of αII- and βII-spectrin. Taken together, despite the diverse roles of spectrins in a variety of other cells, αII- and βII-spectrin do not regulate cell adhesion, cell size and YAP localization in human dermal fibroblasts and are not required for the dermal myofibroblast phenotypical switch.

β2 spectrin-mediated differentiation repressed the properties of liver cancer stem cells through β-catenin

βII-Spectrin (β2SP), a Smad3/4 adaptor protein during transforming growth factor (TGF) β/Smad signal pathway, plays a critical role in suppressing hepatocarcinogenesis. Dedifferentiation is a distinctive feature of cancer progression. Therefore, we investigated whether the disruption of β2SP contributed to tumorigenesis of hepatocellular carcinoma (HCC) through the dedifferentiation. Down-regulation of β2SP in hepatocytes was observed in cirrhotic liver and HCC. The level of β2SP expression was closely associated with the differentiation status of hepatocytes in rat model of hepatocarcinogenesis and clinical specimens. Transgenic expression of β2SP in HCC cells promoted the differentiation of HCC cells and suppressed the growth of HCC cells in vitro. Efficient transduction of β2SP into liver CSCs resulted in a reduction in colony formation ability, spheroid formation capacity, invasive activity, chemo-resistance properties, tumorigenicity in vivo. In addition, β2 spectrin exerted its effect through β catenin in liver CSCs. In conclusion, β2 spectrin repressed the properties of liver CSCs through inducing differentiation; thus, strategies to restore its levels and activities would be a novel strategy for HCC prevention and differentiation therapy

Ethanol sensitizes hepatocytes for TGF-β-triggered apoptosis

Alcohol abuse is a global health problem causing a substantial fraction of chronic liver diseases. Abundant TGF-β—a potent pro-fibrogenic cytokine—leads to disease progression. Our aim was to elucidate the crosstalk of TGF-β and alcohol on hepatocytes. Primary murine hepatocytes were challenged with ethanol and TGF-β and cell fate was determined. Fluidigm RNA analyses revealed transcriptional effects that regulate survival and apoptosis. Mechanistic insights were derived from enzyme/pathway inhibition experiments and modulation of oxidative stress levels. To substantiate findings, animal model specimens and human liver tissue cultures were investigated. Results: On its own, ethanol had no effect on hepatocyte apoptosis, whereas TGF-β increased cell death. Combined treatment led to massive hepatocyte apoptosis, which could also be recapitulated in human HCC liver tissue treated ex vivo. Alcohol boosted the TGF-β pro-apoptotic gene signature. The underlying mechanism of pathway crosstalk involves SMAD and non-SMAD/AKT signaling. Blunting CYP2E1 and ADH activities did not prevent this effect, implying that it was not a consequence of alcohol metabolism. In line with this, the ethanol metabolite acetaldehyde did not mimic the effect and glutathione supplementation did not prevent the super-induction of cell death. In contrast, blocking GSK-3β activity, a downstream mediator of AKT signaling, rescued the strong apoptotic response triggered by ethanol and TGF-β. This study provides novel information on the crosstalk between ethanol and TGF-β. We give evidence that ethanol directly leads to a boost of TGF-β’s pro-apoptotic function in hepatocytes, which may have implications for patients with chronic alcoholic liver disease.

β2-spectrin depletion impairs DNA damage repair

β2-Spectrin (β2SP/SPTBN1, gene SPTBN1) is a key TGF-β/SMAD3/4 adaptor and transcriptional cofactor that regulates TGF-β signaling and can contribute to liver cancer development. Here we report that cells deficient in β2-Spectrin (β2SP) are moderately sensitive to ionizing radiation (IR) and extremely sensitive to agents that cause interstrand cross-links (ICLs) or replication stress. In response to treatment with IR or ICL agents (formaldehyde, cisplatin, camptothecin, mitomycin), β2SP deficient cells displayed a higher frequency of cells with delayed γ-H2AX removal and a higher frequency of residual chromosome aberrations. Following hydroxyurea (HU)-induced replication stress, β2SP-deficient cells displayed delayed disappearance of γ-H2AX foci along with defective repair factor recruitment (MRE11, CtIP, RAD51, RPA, and FANCD2) as well as defective restart of stalled replication forks. Repair factor recruitment is a prerequisite for initiation of DNA damage repair by the homologous recombination (HR) pathway, which was also defective in β2SP deficient cells. We propose that β2SP is required for maintaining genomic stability following replication fork stalling, whether induced by either ICL damage or replicative stress, by facilitating fork regression as well as DNA damage repair by homologous recombination.

Analysis of Genomes and Transcriptomes of Hepatocellular Carcinomas Identifies Mutations and Gene Expression Changes in the Transforming Growth Factor-β Pathway

BACKGROUND & AIMS

Development of hepatocellular carcinoma (HCC) is associated with alterations in the transforming growth factor-beta (TGF-β) signaling pathway, which regulates liver inflammation and can have tumor suppressor or promoter activities. Little is known about the roles of specific members of this pathway at specific of HCC development. We took an integrated approach to identify and validate the effects of changes in this pathway in HCC and identify therapeutic targets.

METHODS

We performed transcriptome analyses for a total of 488 HCCs that include data from The Cancer Genome Atlas. We also screened 301 HCCs reported in the Catalogue of Somatic Mutations in Cancer and 202 from Cancer Genome Atlas for mutations in genome sequences. We expressed mutant forms of spectrin beta, non-erythrocytic 1 (SPTBN1) in HepG2, SNU398, and SNU475 cells and measured phosphorylation, nuclear translocation, and transcriptional activity of SMAD family member 3 (SMAD3).

RESULTS

We found somatic mutations in at least 1 gene whose product is a member of TGF-β signaling pathway in 38% of HCC samples. SPTBN1 was mutated in the largest proportion of samples (12 of 202, 6%). Unsupervised clustering of transcriptome data identified a group of HCCs with activation of the TGF-β signaling pathway (increased transcription of genes in the pathway) and a group of HCCs with inactivation of TGF-β signaling (reduced expression of genes in this pathway). Patients with tumors with inactivation of TGF-β signaling had shorter survival times than patients with tumors with activation of TGF-β signaling (P = .0129). Patterns of TGF-β signaling correlated with activation of the DNA damage response and sirtuin signaling pathways. HepG2, SNU398, and SNU475 cells that expressed the D1089Y mutant or with knockdown of SPTBN1 had increased sensitivity to DNA crosslinking agents and reduced survival compared with cells that expressed normal SPTBN1 (controls).

CONCLUSIONS

In genome and transcriptome analyses of HCC samples, we found mutations in genes in the TGF-β signaling pathway in almost 40% of samples. These correlated with changes in expression of genes in the pathways; up-regulation of genes in this pathway would contribute to inflammation and fibrosis, whereas down-regulation would indicate loss of TGF-β tumor suppressor activity. Our findings indicate that therapeutic agents for HCCs can be effective, based on genetic features of the TGF-β pathway; agents that block TGF-β should be used only in patients with specific types of HCCs.

Brain evolution and development: adaptation, allometry and constraint

Phenotypic traits are products of two processes: evolution and development. But how do these processes combine to produce integrated phenotypes? Comparative studies identify consistent patterns of covariation, or allometries, between brain and body size, and between brain components, indicating the presence of significant constraints limiting independent evolution of separate parts. These constraints are poorly understood, but in principle could be either developmental or functional. The developmental constraints hypothesis suggests that individual components (brain and body size, or individual brain components) tend to evolve together because natural selection operates on relatively simple developmental mechanisms that affect the growth of all parts in a concerted manner. The functional constraints hypothesis suggests that correlated change reflects the action of selection on distributed functional systems connecting the different sub-components, predicting more complex patterns of mosaic change at the level of the functional systems and more complex genetic and developmental mechanisms. These hypotheses are not mutually exclusive but make different predictions. We review recent genetic and neurodevelopmental evidence, concluding that functional rather than developmental constraints are the main cause of the observed patterns.

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).

A Positive TGF-β/c-KIT Feedback Loop Drives Tumor Progression in Advanced Primary Liver Cancer

Hepatocellular carcinoma (HCC) is globally the second most common cause of cancer mortality. The majority of HCC patients are diagnosed at advanced stage disease for which no curative treatments exist. TGF-β has been identified as a potential therapeutic target. However, the molecular mechanisms mediating its functional switch from a tumor suppressor to tumor promoter in HCC and its interactions with other signaling pathways are poorly understood. Here, we demonstrate an aberrant molecular network between the TGF-β and c-KIT pathway that mediates the functional switch of TGF-β to a driver of tumor progression in HCC. TGF-β/SMAD2 signaling transcriptionally regulates expression of the c-KIT receptor ligand (stem cell factor [SCF]) with subsequent auto- and paracrine activation of c-KIT/JAK1/STAT3 signaling. SCF induces TGF-β1 ligand expression via STAT3, thereby forming a positive feedback loop between TGF-β/SMAD and SCF/c-KIT signaling. This network neutralizes TGF-β–mediated cell cycle inhibition and induces tumor cell proliferation, epithelial-to-mesenchymal-transition, migration, and invasion. Disruption of this feedback loop inhibits TGF-β tumor-promoting effects and restores its antiproliferative functions. Consistent with our in vitro data, we demonstrate SCF overexpression and its correlation to SMAD2 and STAT3 activation in human HCC tumors, advanced tumor-node-metastasis stages, and shorter survival. CONCLUSIONS: Canonical TGF-β and c-KIT signaling forms a positive, tumor-promoting feedback loop. Disruption of this loop restores TGF-β tumor suppressor function and provides the rationale for targeting the TGF-β/SCF axis as a novel therapeutic strategy for HCC.

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).

Loss of the transforming growth factor-β effector β2-Spectrin promotes genomic instability

Exposure to genotoxins such as ethanol-derived acetaldehyde leads to DNA damage and liver injury and promotes the development of cancer. We report here a major role for the transforming growth factor β/mothers against decapentaplegic homolog 3 adaptor β2-Spectrin (β2SP, gene Sptbn1) in maintaining genomic stability following alcohol-induced DNA damage. β2SP supports DNA repair through β2SP-dependent activation of Fanconi anemia complementation group D2 (Fancd2), a core component of the Fanconi anemia complex. Loss of β2SP leads to decreased Fancd2 levels and sensitizes β2SP mutants to DNA damage by ethanol treatment, leading to phenotypes that closely resemble those observed in animals lacking both aldehyde dehydrogenase 2 and Fancd2 and resemble human fetal alcohol syndrome. Sptbn1-deficient cells are hypersensitive to DNA crosslinking agents and have defective DNA double-strand break repair that is rescued by ectopic Fancd2 expression. Moreover, Fancd2 transcription in response to DNA damage/transforming growth factor β stimulation is regulated by the β2SP/mothers against decapentaplegic homolog 3 complex.

CONCLUSION

Dysfunctional transforming growth factor β/β2SP signaling impacts the processing of genotoxic metabolites by altering the Fanconi anemia DNA repair pathway. (Hepatology 2017;65:678-693).

Existence of cancer stem cells in hepatocellular carcinoma: myth or reality?

The cancer stem cell (CSC) hypothesis has been disproved in many cancers. CSCs may exist in blood cancer, while many epithelial cancers may not have CSCs but tumor-initiating cells (TICs). Several independent studies have provided strong evidence for existence of CSCs in brain, skin, and colon cancers (Mani et al. in Cell 133:704-715, 2008, Joseph et al. in Cancer Cell 13:129-140, 2008, Reya et al. in Nature 414:105-111, 2001), while the CSC hypothesis remains controversial (Magee et al. in Cancer Cell 21:283-296, 2012). Liver TICs have bipotential to give rise to two different lineage types: hepatocellular carcinoma (HCC) and cholangiocarcinoma (CC). In the liver cancer field, the origin of HCC and CC is extensively debated. Several groups have validated that TICs gave rise to HCC and CC. Hepatocytes gave rise to HCC. Several groups have demonstrated that oval cells (or liver progenitor cells) give rise to TICs. However, CSCs may be a myth in gastrointestinal cancer, while many groups have validated liver TICs. The definition of CSCs includes pluripotency, while TICs do not have to have pluripotency and only need to have bi- or multipotential to give rise to diverse tumor types and tumor initiation potential in mouse models. The CSC hypothesis therefore controversial (Magee et al. in Cancer Cell 21:283-296, 2012). Cancer tissues contain subpopulations of cells known as tumor-initiating stem-like cells (TICs, so-called CSCs) that have been identified as key drivers of tumor growth and malignant progression with drug resistance. Stem cells proliferate via self-renewing division in which the two daughter cells differ in proliferative potential, with one displaying differentiated phenotype and the other retaining self-renewing activity.

MicroRNA-128-3p regulates mitomycin C-induced DNA damage response in lung cancer cells through repressing SPTAN1

The DNA damage response is critical for maintaining genome integrity and preventing damage to DNA due to endogenous and exogenous insults. Mitomycin C (MMC), a potent DNA cross-linker, is used as a chemotherapeutic agent because it causes DNA inter-strand cross-links (DNA ICLs) in cancer cells. While many microRNAs, which may serve as oncogenes or tumor suppressors, are grossly dysregulated in human cancers, little is known about their roles in MMC-treated lung cancer. Here, we report that miR-128-3p can attenuate repair of DNA ICLs by targeting SPTAN1 (αII Sp), resulting in cell cycle arrest and promoting chromosomal aberrations in lung cancer cells treated with MMC. Using computational prediction and experimental validation, SPTAN1 was found to be a conserved target of miR-128-3p. We then found that miR-128-3p caused translational inhibition of SPTAN1, reducing its protein level. SPTAN1 repression via miR-128-3p also induced cell cycle arrest and chromosomal instability. Additionally, miR-128-3p significantly influenced interaction of the αII Sp/FANCA/XPF complex, thus limiting DNA repair. In summary, the results demonstrate that miR-128-3p accelerates cell cycle arrest and chromosomal instability in MMC-treated lung cancer cells by suppressing SPTAN1, and these findings could be applied for adjuvant chemotherapy of lung cancer.

Nonalcoholic fatty liver disease and hepatocellular carcinoma

The fastest growing cause of cancer-related death is hepatocellular carcinoma (HCC), which is at least partly attributable to the rising prevalence of non-alcoholic fatty liver disease. Non-alcoholic fatty liver disease (NAFLD) encompasses a broad spectrum of conditions, ranging from non-progressive bland steatosis to malignant transformation into hepatocellular cancer. The estimated annual HCC incidence in the progressive form of NAFLD - non-alcoholic steatohepatitis (NASH) - is about 0.3%. The risk of HCC development is higher in men and increases with age, more advanced fibrosis, progressive obesity, insulin resistance and diabetes mellitus. Studies on the molecular mechanism of HCC development in NAFLD have shown that hepatocarcinogenesis is associated with complex changes at the immunometabolic interface. In line with these clinical risk factors, administration of a choline-deficient high-fat diet to mice over a prolonged period results in spontaneous HCC development in a high percentage of animals. The role of altered insulin signaling in tumorigenesis is further supported by the observation that components of the insulin-signaling cascade are frequently mutated in hepatocellular cancer cells. These changes further enhance insulin-mediated growth and cell division of hepatocytes. Furthermore, studies investigating nuclear factor kappa B (NF-κB) signaling and HCC development allowed dissection of the complex links between inflammation and carcinogenesis. To conclude, NAFLD reflects an important risk factor for HCC, develops also in non-cirrhotic livers and is a prototypic cancer involving inflammatory and metabolic pathways. STRENGTHS/WEAKNESSES AND SUMMARY OF THE TRANSLATIONAL POTENTIAL OF THE MESSAGES IN THE PAPER: The systematic review summarizes findings from unbiased clinical and translational studies on hepatocellular cancer in non-alcoholic fatty liver disease. This provides a concise overview on the epidemiology, risk factors and molecular pathogenesis of the NAFL-NASH-HCC sequence. One limitation in the field is that few HCC studies stratify patients by underlying etiology, although the etiology of the underlying liver disease is an important co-determinant of clinical disease course and molecular pathogenesis. Molecular profiling of NAFL and associated HCC holds great translational potential for individualized surveillance, prevention and therapy.

Vitamin D Deficiency Promotes Liver Tumor Growth in Transforming Growth Factor-β/Smad3-Deficient Mice Through Wnt and Toll-like Receptor 7 Pathway Modulation

Disruption of the TGF-β pathway is associated with liver fibrosis and suppression of liver tumorigenesis, conditions associated with low Vitamin D (VD) levels. However, potential contributions of VD to liver tumor progression in the context of TGF-β signaling remain unexplored. Our analyses of VD deprivation (VDD) in in vivo models of liver tumor formation revealed striking three-fold increases in tumor burden in Smad3(+/-) mice, with a three-fold increase in TLR7 expression compared to controls. ChIP and transcriptional assays confirm Smad3 binding at two TLR7 promoter SBE sites. Molecular interactions between TGF-β pathway and VDD were validated clinically, where an absence of VD supplementation was associated with low TGF-β pathway member expression levels and β-catenin activation in fibrotic/cirrhotic human liver tissues. Subsequent supplementing VD led to restoration of TGF-β member expression with lower β-catenin levels. Bioinformatics analysis provides positive supportive correlation between somatic mutations for VD-related genes and the TGF-β pathway. We conclude that VDD promotes tumor growth in the context of Smad3 disruption, potentially through regulation of TLR7 expression and β-catenin activation. VD could therefore be a strong candidate for liver cancer prevention in the context of aberrant Smad3 signaling.

Computational Identification of Novel Stage-Specific Biomarkers in Colorectal Cancer Progression

It is well-known that the conversion of normal colon epithelium to adenoma and then to carcinoma stems from acquired molecular changes in the genome. The genetic basis of colorectal cancer has been elucidated to a certain extent, and much remains to be known about the identity of specific cancer genes that are associated with the advancement of colorectal cancer from one stage to the next. Here in this study we attempted to identify novel cancer genes that could underlie the stage-specific progression and metastasis of colorectal cancer. We conducted a stage-based meta-analysis of the voluminous tumor genome-sequencing data and mined using multiple approaches for novel genes driving the progression to stage-II, stage-III and stage-IV colorectal cancer. The consensus of these driver genes seeded the construction of stage-specific networks, which were then analyzed for the centrality of genes, clustering of subnetworks, and enrichment of gene-ontology processes. Our study identified three novel driver genes as hubs for stage-II progression: DYNC1H1, GRIN2A, GRM1. Four novel driver genes were identified as hubs for stage-III progression: IGF1R, CPS1, SPTA1, DSP. Three novel driver genes were identified as hubs for stage-IV progression: GSK3B, GGT1, EIF2B5. We also identified several non-driver genes that appeared to underscore the progression of colorectal cancer. Our study yielded potential diagnostic biomarkers for colorectal cancer as well as novel stage-specific drug targets for rational intervention. Our methodology is extendable to the analysis of other types of cancer to fill the gaps in our knowledge.

TGF-β signaling in liver and gastrointestinal cancers

Transforming Growth Factor-β (TGF-β) plays crucial and complex roles in liver and gastrointestinal cancers. These include a multitude of distinct functions, such as maintaining stem cell homeostasis, promoting fibrosis, immune modulating, as a tumor suppressor and paradoxically, as a tumor progressor. However, key mechanisms for the switches responsible for these distinct actions are poorly understood, and remain a challenge. The Cancer Genome Atlas (TCGA) analyses and genetically engineered mouse models now provide an integrated approach to dissect these multifaceted and context-dependent driving roles of the TGF-β pathway. In this review, we will discuss the molecular mechanisms of TGF-β signaling, focusing on colorectal, gastric, pancreatic, and liver cancers. Novel drugs targeting the TGF-β pathway have been developed over the last decade, and some have been proven effective in clinical trials. A better understanding of the TGF-β pathway may improve our ability to target it, thus providing more tools to the armamentarium against these deadly cancers.

Cancer Stem Cell and Gastrointestinal Cancer: Current Status, Targeted Therapy and Future Implications

The cancer stem cells (CSCs) are biologically distinct subset of rare cancer cells with inherent ability of self-renewal, de-differentiation, and capacity to initiate and maintain malignant tumor growth. Studies have further reported that CSCs prime cancer recurrence and therapy resistance. Therefore, targeting CSCs to inhibit cancer progression has become an attractive anti-cancer therapeutical strategy. Recent technical advances have provided a greater appreciation of the multistep nature of the oncogenesis and also clarified that CSC concept is not universally applicable. Irrespective, the role of the CSCs in gastrointestinal (GI) cancers, responsible for the most cancer-associated death, has been widely accepted and appreciated. However, despite the tremendous progress made in the last decade in developing markers to identify CSCs, and assays to assess tumorigenic function of CSCs, it remains an area of active investigation. In current article, we review findings related to the role and identification of CSCs in GI-cancers and discuss the crucial pathways involved in regulating CSCs populations’ development and drug resistance, and use of the tumoroid culture to test novel CSCs-targeted cancer therapies.

Hepatocellular carcinoma mouse models: Hepatitis B virus-associated hepatocarcinogenesis and haploinsufficient tumor suppressor genes

The multifactorial and multistage pathogenesis of hepatocellular carcinoma (HCC) has fascinated a wide spectrum of scientists for decades. While a number of major risk factors have been identified, their mechanistic roles in hepatocarcinogenesis still need to be elucidated. Many tumor suppressor genes (TSGs) have been identified as being involved in HCC. These TSGs can be classified into two groups depending on the situation with respect to allelic mutation/loss in the tumors: the recessive TSGs with two required mutated alleles and the haploinsufficient TSGs with one required mutated allele. Hepatitis B virus (HBV) is one of the most important risk factors associated with HCC. Although mice cannot be infected with HBV due to the narrow host range of HBV and the lack of a proper receptor, one advantage of mouse models for HBV/HCC research is the numerous and powerful genetic tools that help investigate the phenotypic effects of viral proteins and allow the dissection of the dose-dependent action of TSGs. Here, we mainly focus on the application of mouse models in relation to HBV-associated HCC and on TSGs that act either in a recessive or in a haploinsufficient manner. Discoveries obtained using mouse models will have a great impact on HCC translational medicine.

Caspase-3/7-mediated Cleavage of β2-spectrin is Required for Acetaminophen-induced Liver Damage

The ubiquitously expressed β2-spectrin (β2SP, SPTBN1) is the most common non-erythrocytic member of the β-spectrin gene family. Loss of β2-spectrin leads to defects in liver development, and its haploinsufficiency spontaneously leads to chronic liver disease and the eventual development of hepatocellular cancer. However, the specific role of β2-spectrin in liver homeostasis remains to be elucidated. Here, we reported that β2-spectrin was cleaved by caspase-3/7 upon treatment with acetaminophen which is the main cause of acute liver injury. Blockage of β2-spectrin cleavage robustly attenuated β2-spectrin-specific functions, including regulation of the cell cycle, apoptosis, and transcription. Cleaved fragments of β2-spectrin were physiologically active, and the N- and C-terminal fragments retained discrete interaction partners and activity in transcriptional regulation and apoptosis, respectively. Cleavage of β2-spectrin facilitated the redistribution of the resulting fragments under conditions of liver damage induced by acetaminophen. In contrast, downregulation of β2-spectrin led to resistance to acetaminophen-induced cytotoxicity, and its insufficiency in the liver promoted suppression of acetaminophen-induced liver damage and enhancement of liver regeneration.

CONCLUSIONS

β2-Spectrin, a TGF-β mediator and signaling molecule, is cleaved and activated by caspase-3/7, consequently enhancing apoptosis and transcriptional control to determine cell fate upon liver damage. These findings have extended our knowledge on the spectrum of β2-spectrin functions from a scaffolding protein to a target and transmitter of TGF-β in liver damage.

Leveraging a Multi-Omics Strategy for Prioritizing Personalized Candidate Mutation-Driver Genes: A Proof-of-Concept Study

The expression of mutant forms of proteins (e.g., oncogenes and tumor suppressors) has implications in cancer biology and clinical practice. Initial efforts have been made to characterize the transcription of tumor-mutated alleles; however, few studies have been reported to link tumor-mutated alleles to proteomics. We aimed to characterize the transcriptional and translational patterns of tumor-mutated alleles. We performed whole-exome sequencing, RNA-seq, and proteome profiling in a hyper-mutated patient of hepatocellular carcinoma. Using the patient as a model, we show that only a small proportion of tumor-mutated alleles were expressed. In this case, 42% and 3.5% of the tumor-mutated alleles were identified to be transcribed and translated, respectively. Compared with genes with germline variations or without mutations, somatic mutations significantly reduced protein expression abundance. Using the transcriptional and translational patterns of tumor-mutated alleles, we classified the mutations into four types, and only one type may be associated with the liver cancer and lead to hepatocarcinogenesis in the patient. Our results demonstrate how tumor-mutated alleles are transcribed and translated, and how the expression enables the classification of somatic mutations that cause cancer. Leveraging multiple ‘omics’ datasets provides a new avenue for understanding patient-specific mutations that underlie carcinogenesis.

Apoptosis in liver carcinogenesis and chemotherapy

Hepatocellular carcinoma (HCC) is a major health problem. In human hepatocarcinogenesis, the balance between cell death and proliferation is deregulated, tipping the scales for a situation where antiapoptotic signals are overpowering the death-triggering stimuli. HCC cells harbor a wide variety of mutations that alter the regulation of apoptosis and hence the response to chemotherapeutical drugs, making them resistant to the proapoptotic signals. Considering all these modifications found in HCC cells, therapeutic approaches need to be carefully studied in order to specifically target the antiapoptotic signals. This review deals with the recent relevant contributions reporting molecular alterations for HCC that lead to a deregulation of apoptosis, as well as the challenge of death-inducing chemotherapeutics in current HCC treatment.

Comparative study of the effects of PEGylated interferon-α2a versus 5-fluorouracil on cancer stem cells in a rat model of hepatocellular carcinoma

Cancer stem cells (CSCs) in hepatocellular carcinoma (HCC) possess tumor-initiating, metastatic, and drug resistance properties. This study was conducted to evaluate the effects of PEGylated interferon-α2a (PEG-IFN-α2a) and 5-fluorouracil (5-FU) on the expression of CSC markers and on specific pathways that contribute to the propagation of CSCs in HCC. HCC was initiated in rats using a single intraperitoneal dose of diethylnitrosamine (DENA) (200 mg/kg) and promoted by weekly subcutaneous injections of carbon tetrachloride (CCl4) for 6 weeks. After the appearance of dysplastic nodules, the animals received PEG-IFN-α2a or 5-FU for 8 weeks. CSC markers (OV6, CD90) and molecules related to transforming growth factor β (TGF-β) and other signaling pathways were assessed in hepatic tissues. The PEG-IFN-α2a treatment effectively suppressed the hepatic expression of OV6 and CD90, ameliorated the diminished hepatic expression of TGF-β receptor II (TGF-βRII) and β2-spectrin (β2SP), and significantly reduced the elevated hepatic expression of TGF-β1, interleukin6 (IL6), signal transducer and activator of transcription3 (STAT3), and vascular endothelial growth factor (VEGF). In contrast, the 5-FU treatment failed to reduce the overexpression of CSC markers and barely affected the disrupted TGF-β signaling. Furthermore, it had no effect on angiogenesis or nitrosative stress. PEG-IFN-α2a, but not 5-FU, could reduce the propagation of CSCs during the progression of HCC by upregulating the disrupted TGF-β signaling, suppressing the IL6/STAT3 pathway and reducing angiogenesis.