Enhanced self-renewal capability in hepatic stem/progenitor cells drives cancer initiation

Cancer stem cells: advances in knowledge and implications for cancer therapy

Cancer stem cells (CSCs), a small subset of cells in tumors that are characterized by self-renewal and continuous proliferation, lead to tumorigenesis, metastasis, and maintain tumor heterogeneity. Cancer continues to be a significant global disease burden. In the past, surgery, radiotherapy, and chemotherapy were the main cancer treatments. The technology of cancer treatments continues to develop and advance, and the emergence of targeted therapy, and immunotherapy provides more options for patients to a certain extent. However, the limitations of efficacy and treatment resistance are still inevitable. Our review begins with a brief introduction of the historical discoveries, original hypotheses, and pathways that regulate CSCs, such as WNT/β-Catenin, hedgehog, Notch, NF-κB, JAK/STAT, TGF-β, PI3K/AKT, PPAR pathway, and their crosstalk. We focus on the role of CSCs in various therapeutic outcomes and resistance, including how the treatments affect the content of CSCs and the alteration of related molecules, CSCs-mediated therapeutic resistance, and the clinical value of targeting CSCs in patients with refractory, progressed or advanced tumors. In summary, CSCs affect therapeutic efficacy, and the treatment method of targeting CSCs is still difficult to determine. Clarifying regulatory mechanisms and targeting biomarkers of CSCs is currently the mainstream idea.

Bmi1 facilitates the progression of cholangiocarcinoma by inhibiting Foxn2 expression dependent on a histone H2A ubiquitination manner

Cholangiocarcinoma (CCA), an exceptionally aggressive malignancy originating from the epithelium of the bile duct, poses a formidable challenge in cancer research and clinical management. Currently, attention is focused on exploring the oncogenic role and prognostic implications associated with Bmi1 in the context of CCA. In our study, we assessed the correlation of Bmi1 and Foxn2 expression across all types of CCA and evaluated their prognostic significance. Our results demonstrated that Bmi1 exhibits significantly upregulated expression in CCA tissues, while Foxn2 expression shows an inverse pattern. Simultaneously, the high expression of Bmi1, coupled with the low expression of Foxn2, indicates an unfavorable prognosis. Through in vitro and in vivo experiments, we confirmed the crucial role of Foxn2 in the proliferation, metastasis, and epithelial-mesenchymal transition (EMT) of CCA. Mechanistically, Bmi1 promotes the ubiquitination of histone H2A (H2AUb), leading to chromatin opening attenuation and a decrease in Foxn2 expression, ultimately driving CCA progression. Additionally, we described the potential value of Bmi1 and H2AUb inhibitors in treating CCA through in vitro experiments and orthotopic models. This study is of significant importance in deepening our understanding of the interaction between Bmi1 and Foxn2 in CCA and has the potential to advance the development of precision therapies for CCA.

An integrated investigation of sulfotransferases (SULTs) in hepatocellular carcinoma and identification of the role of SULT2A1 on stemness

The cytosolic sulfotransferases (SULTs) are phase II conjugating enzymes, which are widely expressed in the liver and mainly mediate the sulfation of numerous xenobiotics and endogenous compounds. However, the role of various SULTs genes has not been reported in hepatocellular carcinoma (HCC). This study aims to analyze the expression and potential functional roles of SULTs genes in HCC and to identify the role of SULT2A1 in HCC stemness as well as the possible mechanism. We found that all of the 12 SULTs genes were differentially expressed in HCC. Moreover, clinicopathological features and survival rates were also investigated. Multivariate regression analysis showed that SULT2A1 and SULT1C2 could be used as independent prognostic factors in HCC. SULT1C4, SULT1E1, and SULT2A1 were significantly associated with immune infiltration. SULT2A1 deficiency in HCC promoted chemotherapy resistance and stemness maintenance. Mechanistically, silencing of SULT2A1 activated the AKT signaling pathway, on the one hand, promoted the expression of downstream stemness gene c-Myc, on the other hand, facilitated the NRF2 expression to reduce the accumulation of ROS, and jointly increased HCC stemness. Moreover, knockdown NR1I3 was involved in the transcriptional regulation of SULT2A1 in stemness maintenance. In addition, SULT2A1 knockdown HCC cells promoted the proliferation and activation of hepatic stellate cells (HSCs), thereby exerting a potential stroma remodeling effect. Our study revealed the expression and role of SULTs genes in HCC and identified the contribution of SULT2A1 to the initiation and progression of HCC.

Pleiotropic physiological functions of Piezo1 in human body and its effect on malignant behavior of tumors

Mechanosensitive ion channel protein 1 (Piezo1) is a large homotrimeric membrane protein. Piezo1 has various effects and plays an important and irreplaceable role in the maintenance of human life activities and homeostasis of the internal environment. In addition, recent studies have shown that Piezo1 plays a vital role in tumorigenesis, progression, malignancy and clinical prognosis. Piezo1 is involved in regulating the malignant behaviors of a variety of tumors, including cellular metabolic reprogramming, unlimited proliferation, inhibition of apoptosis, maintenance of stemness, angiogenesis, invasion and metastasis. Moreover, Piezo1 regulates tumor progression by affecting the recruitment, activation, and differentiation of multiple immune cells. Therefore, Piezo1 has excellent potential as an anti-tumor target. The article reviews the diverse physiological functions of Piezo1 in the human body and its major cellular pathways during disease development, and describes in detail the specific mechanisms by which Piezo1 affects the malignant behavior of tumors and its recent progress as a new target for tumor therapy, providing new perspectives for exploring more potential effects on physiological functions and its application in tumor therapy.

Combined Hepatocellular-Cholangiocarcinoma: Biology, Diagnosis, and Management

BACKGROUND

Combined hepatocellular-cholangiocarcinoma (cHCC-iCCA) is a rare type of primary liver cancer displaying characteristics of both hepatocytic and cholangiocytic differentiation.

SUMMARY

Because of its aggressive nature, patients with cHCC-iCCA exhibit a poorer prognosis than those with HCC. Surgical resection and liver transplantation may be considered curative treatment approaches; however, only a minority of patients are eligible at the time of diagnosis, and postoperative recurrence rates are high. For cases that are not eligible for surgery, locoregional and systemic therapy are often administered based on treatment protocols applied for HCC or iCCA. Owing to the rarity of this cancer, there are still no established standard treatment protocols; therefore, the choice of therapy is often personalized and guided by the suspected predominant component. Further, the genomic and molecular heterogeneity of cHCC-iCCA can severely compromise the efficacy of the available therapies.

KEY MESSAGES

In the present review, we summarize the latest advances in cHCC-iCCA and attempt to clarify its terminology and molecular biology. We provide an overview of the etiology of cHCC-iCCA and present new insights into the molecular pathology of this disease that could contribute to further studies aiming to improve the patient outcomes through new systemic therapies.

Management of Locally Advanced or Metastatic Combined Hepatocellular Cholangiocarcinoma

Combined hepatocellular cholangiocarcinoma (cHCC-CC) is a rare primary liver malignancy that comprises features of hepatocellular carcinoma (HCC) and cholangiocarcinoma (CC). Due to the rarity of this tumor, the treatment of choice has not yet been defined. For resectable disease, liver resection is the mainstay treatment. However, most patients relapse or display advanced disease and were not surgical candidates. Although the majority of patients are either primarily or secondarily treated in palliative intent, no guideline recommendations or prospective trial reports exist to allow reliable evaluation of debated treatment options. We review different locoregional or medical treatment options for advanced combined hepatocellular cholangiocarcinoma (cHCC-CC) in the neoadjuvant, adjuvant, or palliative setting and discuss the possibility of predictive biomarker-guided therapeutic options.

Current view of liver cancer cell-of-origin and proposed mechanisms precluding its proper determination

Hepatocellular carcinoma and intrahepatic cholangiocarcinoma are devastating primary liver cancers with increasing prevalence in many parts of the world. Despite intense investigation, many aspects of their biology are still largely obscure. For example, numerous studies have tackled the question of the cell-of-origin of primary liver cancers using different experimental approaches; they have not, however, provided a clear and undisputed answer. Here, we will review the evidence from animal models supporting the role of all major types of liver epithelial cells: hepatocytes, cholangiocytes, and their common progenitor as liver cancer cell-of-origin. Moreover, we will also propose mechanisms that promote liver cancer cell plasticity (dedifferentiation, transdifferentiation, and epithelial-to-mesenchymal transition) which may contribute to misinterpretation of the results and which make the issue of liver cancer cell-of-origin particularly complex.

Targeted Therapies for Hepatocellular Carcinoma Treatment: A New Era Ahead-A Systematic Review

Hepatocellular carcinoma (HCC) remains one of the most common malignancies and the third cause of cancer-related death worldwide, with surgery being the best prognostic tool. Among the well-known causative factors of HCC are chronic liver virus infections, chronic virus hepatitis B (HBV) and chronic hepatitis virus C (HCV), aflatoxins, tobacco consumption, and non-alcoholic liver disease (NAFLD). There is a need for the development of efficient molecular markers and alternative therapeutic targets of great significance. In this review, we describe the general characteristics of HCC and present a variety of targeted therapies that resulted in progress in HCC therapy.

Glutamine metabolism in cancers: Targeting the oxidative homeostasis

Glutamine is the most abundant amino acid in blood and tissues, and the most important nutrient except for glucose in cancer cells. Over the past years, most studies have focused on the role of Gln metabolism in supporting energy metabolism rather than maintaining oxidative homeostasis. In fact, Gln is an important factor in maintaining oxidative homeostasis of cancer cells, especially in “Glutamine addicted” cancer cells. Here, this paper will review the recent scientific literature about the link between Gln metabolism and oxidative homeostasis, with an emphasis on the potential role of Gln metabolism in different cancers. Given that oxidative homeostasis is of critical importance in cancer, understanding the impacts of a Gln metabolism on oxidative homeostasis, gaining great insights into underlying molecular mechanisms, and developing effective therapeutic strategies are of great importance.

Tumor Necrosis Factor-α (TNFα) Stimulate Triple-Negative Breast Cancer Stem Cells to Promote Intratumoral Invasion and Neovasculogenesis in the Liver of a Xenograft Model

TNBC represents the most aggressive breast cancer subtype. Although cancer stem cells (CSCs) are a minor fraction of all cancer cells, they are highly cancerous when compared to their non-stem counterparts, playing a major role in tumor recurrence and metastasis. Angiogenic stimuli and the tumor environment response are vital factors in cancer metastasis. However, the causes and effects of tumor angiogenesis are still poorly understood. In this study, we demonstrate TNFα effects on primary triple-negative breast cancer stem cells (BCSCs). TNFα stimulation increased the mesenchymality of BCSCs in an intermediate epithelial-to-mesenchymal transition (EMT) state, enhanced proliferation, self-renewal, and invasive capacity. TNFα-treatment elicited BCSC signaling on endothelial networks in vitro and increased the network forming capacity of the endothelial cells. Our findings further demonstrate that TNFα stimulation in BCSCs has the ability to instigate distinct cellular communication within the tumor microenvironment, inducing intra-tumoral stromal invasion. Further, TNFα-treatment in BCSCs induced a pre-metastatic niche through breast-liver organ crosstalk by inducing vascular cell adhesion molecule-1 (VCAM-1) enriched neovasculogenesis in the liver of tumor-bearing mice. Overall, TNFα is an important angiogenic target to be considered in breast cancer progression to attenuate any angiogenic response in the tumor environment that could lead to secondary organ metastasis.

Roles of BMI1 in the Initiation, Progression, and Treatment of Hepatocellular Carcinoma

Liver cancer has high rates of morbidity and mortality, and its treatment is a global health challenge. Hepatocellular carcinoma (HCC) accounts for 90% of all primary liver cancer cases. B-lymphoma Mo-MLV insertion region 1 (BMI1) has been identified as a proto-oncogene, which contributes to the initiation and progression of many malignant tumors. BMI1 expression is upregulated in HCC, and it influences the occurrence and development of HCC by various mechanisms, such as the INK4a/ARF locus, NF-κB signaling pathway, and PTEN/PI3K/AKT signaling pathway. In addition, the expression of BMI1 is related to prognosis and recurrence of HCC. Hence, there is clear evidence that BMI1 is a novel and valid therapeutic target for HCC. Accordingly, the development of therapeutic strategies targeting BMI1 has been a focus of recent research, providing new directions for HCC treatment. This review summarizes the role of BMI1 in the occurrence and treatment of HCC, which will provide a basis for using BMI1 as a potential target for the development of therapeutic strategies for HCC.

Direct molecular evidence for both multicentric and monoclonal carcinogenesis followed by transdifferentiation from hepatocellular carcinoma to cholangiocarcinoma in a case of metachronous liver cancer

Frequent recurrence is a major issue in liver cancer and histological heterogeneity frequently occurs in this cancer type. However, it has remained elusive whether such cancers are multicentric or monoclonal. To elucidate the clonal evolution of hepatocellular carcinoma (HCC) recurrence and combined hepatocellular-cholangiocarcinoma (cHCC-CCA) development, the somatic mutation frequency and signatures in a patient with triple occurrence of liver cancer every three years were examined, with samples designated as #1HCC, #2HCC and #3cHCC-CCA, respectively. A total of four tumor regions, including HCC (#3HCC) and intrahepatic CCA (#3iCCA) components of #3cHCC-CCA, and three nontumor regions (#1N, #2N and #3N) were precisely dissected from formalin-fixed paraffin-embedded tissues of each surgical specimen. DNA was extracted and subjected to tumor-specific somatic mutation determination. Of note, five nonsynonymous single-nucleotide variants (SNVs), namely those of KMT2D, TP53, DNMT3A, PKHD1 and TLR4, were identified in #3cHCC-CCA. All five SNVs were detected in both #3HCC and #3iCCA and #2HCC but not in #1HCC. The telomerase reverse transcriptase (TERT) promoter mutation C228T, but not C250T, was observed in all tumors. Digital PCR of C228T also indicated the presence of the TERT promoter mutation C228T in nontumorous liver tissues (#1N, #2N and #3N) at a frequency of 0.11-0.83% compared with normal liver and blood samples. These results suggest the following phylogenetic evolution of three metachronous liver cancers: #1HCC was not related to #2HCC, #3HCC and #3iCCA; both #3HCC and #3iCCA arose from #2HCC. From the above, three novel findings were deduced: i) Both multicentric occurrence and intrahepatic metastasis may be involved in liver cancer in a three-year interval; ii) transdifferentiation from HCC to iCCA is a possible pathogenic mechanism of cHCC-CCA; and iii) a nontumorous, noncirrhotic liver may contain a preneoplastic region with a cancer driver mutation in the TERT promoter.

Natural products targeting cancer stem cells: Implications for cancer chemoprevention and therapeutics

Cancer, being the leading cause of death in the globe, has been one of the major thrust areas of research worldwide. In a new paradigm about neoplastic transformations, the initiation and recurrence of disease is attributed to few mutated cells in bulk of tumor called cancer stem cells (CSCs). CSCs have capacity of self-renewal and differentiation, which are known for resistance to radio and chemotherapy leading to recurrence of the disease even after treatment. Most of traditional drugs implicated in cancer therapy targeting primary tumors have substantial toxicity to the physiological system and have not been efficient in targeting these CSCs leading to poor prognosis. Targeting these CSCs in bulk of tumor might be novel strategy for cancer chemoprevention and therapeutics. Diet-derived interventions and diverse natural products are known to target these CSCs and related signaling pathways, namely, Wnt, Notch, and Hedgehog pathways, which are implicated for CSC self-renewal. PRACTICAL APPLICATIONS: Cancer remains a global challenge even in this century. Poor prognosis, survival rate, and recurrence of the disease have been the major concerns in traditional cancer therapy regimes. Targeting cancer stem cells might be novel strategy for elimination and cure of the chronic disease as they are known to modulate all stages of carcinogenesis and responsible for recurrence and resistance to chemotherapy and radiotherapy. The evidence support that natural products might inhibit, delay, or reverse the process of tumorigenesis and modulate the different signaling pathways implicated for cancer stem cells self-renewal and differentiation. Natural products have minimal toxicity compared to traditional cancer therapy drugs since they have long been utilized in our food habits without any major side effects reported. Thus, targeting cancer stem cells with natural product might be a novel strategy for drug development in cancer chemoprevention and therapeutics.

Combined hepatocellular-cholangiocarcinoma: An update

Combined hepatocellular-cholangiocarcinoma (cHCC-CCA) is a tumour that exhibits both hepatocytic and biliary differentiation. Classical risk factors for hepatocellular carcinoma (HCC) seem to also predispose patients to the development of cHCC-CCA. The pathological definition of cHCC-CCA has significantly evolved over time. The last 2019 WHO classification highlighted that the diagnosis of cHCC-CCA should be primarily based on morphology using routine stainings, with additional immunostaining used to refine the identification of subtypes. Among them, "intermediate cell carcinoma" is recognised as a specific subtype, while "cholangiolocellular carcinoma" is now considered a subtype of iCCA. Increasing molecular evidence supports the clonal nature of cHCC-CCA and parallels its biphenotypic histological appearance, with genetic alterations that are classically observed in HCC and/or iCCA. That said, the morphological diagnosis of cHCC-CCA is still challenging for radiologists and pathologists, especially on biopsy specimens. Identification of cHCC-CCA's cell of origin remains an area of active research. Its prognosis is generally worse than that of HCC, and similar to that of iCCA. Resection with lymph node dissection is unfortunately the only curative option for patients with cHCC-CCA. Thus, there remains an urgent need to develop specific therapeutic strategies for this unique clinical entity.

Cell of origin in biliary tract cancers and clinical implications

Biliary tract cancers (BTCs) are aggressive epithelial malignancies that can arise at any point of the biliary tree. Albeit rare, their incidence and mortality rates have been rising steadily over the past 40 years, highlighting the need to improve current diagnostic and therapeutic strategies. BTCs show high inter- and intra-tumour heterogeneity both at the morphological and molecular level. Such complex heterogeneity poses a substantial obstacle to effective interventions. It is widely accepted that the observed heterogeneity may be the result of a complex interplay of different elements, including risk factors, distinct molecular alterations and multiple potential cells of origin. The use of genetic lineage tracing systems in experimental models has identified cholangiocytes, hepatocytes and/or progenitor-like cells as the cells of origin of BTCs. Genomic evidence in support of the distinct cell of origin hypotheses is growing. In this review, we focus on recent advances in the histopathological subtyping of BTCs, discuss current genomic evidence and outline lineage tracing studies that have contributed to the current knowledge surrounding the cell of origin of these tumours.

Lineage tracing: technology tool for exploring the development, regeneration, and disease of the digestive system

Lineage tracing is the most widely used technique to track the migration, proliferation, and differentiation of specific cells in vivo. The currently available gene-targeting technologies have been developing for decades to study organogenesis, tissue injury repairing, and tumor progression by tracing the fates of individual cells. Recently, lineage tracing has expanded the platforms available for disease model establishment, drug screening, cell plasticity research, and personalized medicine development in a molecular and cellular biology perspective. Lineage tracing provides new views for exploring digestive organ development and regeneration and techniques for digestive disease causes and progression. This review focuses on the lineage tracing technology and its application in digestive diseases.

Targeting Liver Cancer Stem Cells: An Alternative Therapeutic Approach for Liver Cancer

The first report of cancer stem cell (CSC) from Bruce et al. has demonstrated the relatively rare population of stem-like cells in acute myeloid leukemia (AML). The discovery of leukemic CSCs prompted further identification of CSCs in multiple types of solid tumor. Recently, extensive research has attempted to identity CSCs in multiple types of solid tumors in the brain, colon, head and neck, liver, and lung. Based on these studies, we hypothesize that the initiation and progression of most malignant tumors rely largely on the CSC population. Recent studies indicated that stem cell-related markers or signaling pathways, such as aldehyde dehydrogenase (ALDH), CD133, epithelial cell adhesion molecule (EpCAM), Wnt/β-catenin signaling, and Notch signaling, contribute to the initiation and progression of various liver cancer types. Importantly, CSCs are markedly resistant to conventional therapeutic approaches and current targeted therapeutics. Therefore, it is believed that selectively targeting specific markers and/or signaling pathways of hepatic CSCs is an effective therapeutic strategy for treating chemotherapy-resistant liver cancer. Here, we provide an overview of the current knowledge on the hepatic CSC hypothesis and discuss the specific surface markers and critical signaling pathways involved in the development and maintenance of hepatic CSC subpopulations.

Cancer stem cell plasticity in glioblastoma multiforme: a perspective on future directions in oncolytic virotherapy

The cancer stem cell (CSC) hypothesis suggests that a rare population of stem-like cells underpin tumorigenesis. Oncolytic viruses (OVs) demonstrate novel mechanisms of targeting the elusive CSCs with greater selectivity - promising therapeutic potential against solid tumors such as glioblastoma (GBM) that are resistant to conventional treatment. In general, OVs have failed to translate the efficacy from bench to bedside. The success of OVs rely on the hypothesis that eliminating CSCs is key to preventing recurrence. However, newly emerging evidence of CSC plasticity challenge this hypothesis by proposing that the CSC pool can be regenerated from non-CSCs post-treatment. We review this evidence surrounding the CSC hypothesis to propose an original perspective on why several advanced OVs may be failing to reflect their true potential in clinical trials. We argue that preventing non-CSC to CSC dedifferentiation may be critical to achieving long-term treatment efficacy in future OV clinical trials.

Ring1 promotes the transformation of hepatic progenitor cells into cancer stem cells through the Wnt/β-catenin signaling pathway

The proliferation of hepatic progenitor cells (HPCs) is observed in reactive conditions of the liver and primary liver cancers. Ring1 as a member of polycomb-group proteins which play vital roles in carcinogenesis and stem cell self-renewal was increased in HCC patients and promoted proliferation and survival of cancer cell by degrading p53. However, the mechanisms of Ring1 driving the progression of hepatocarcinogenesis have not been elucidated. In this study, forced expression Ring1 and Ring1 siRNA lentiviral vectors were utilized to stably overexpression and silence Ring1 in HPC cell line (WB-F344), respectively. Our finding indicated that overexpression of Ring1 in HPCs promoted colony formation, cell multiplication, and invasion in vitro, conversely depletion of Ring1 repressed the biological functions of HPCs relative to controls. The expression of β-catenin was upregulated in the HPCs with overexpression of Ring1, and the correlation analysis also showed that β-catenin and Ring1 had a significant correlation in the liver cancer tissues and adjacent tissues. The activation of the Wnt/β-catenin signaling pathway significantly increased the expression of liver cancer stem cells related (LCSCs)-related molecular markers CD90 and EpCAM, which led to the transformation of HPCs into LCSCs. Most importantly, the injection of HPCs with overexpressed Ring1 into the subcutaneous of nude mice leads to the formation of poorly differentiated HCC neoplasm. Our findings elucidate that overexpression of Ring1 the activated Wnt/β-catenin signaling pathway and drove the transformation of HPCs into cancer stem cell-like cells, suggesting Ring1 has extraordinary potential in early diagnosis of HCC.

Predictors of recurrence and survival of hepatocellular carcinoma: A prospective study including transient elastography and cancer stem cell markers

BACKGROUND AND STUDY AIMS

To investigate whether the measurement of liver stiffness (LSM) using fibroscan and the serum Cancer Stem Cells (CSC): Ep-CAM and cytokeratin-19, could predict the recurrence of hepatocellular carcinoma (HCC) and their impact on clinical outcome and overall survival.

PATIENTS AND METHODS

This is a prospective study, including 179 HCV-related HCC patients. All patients were treated following the BCLC guidelines. All HCC patients had transient elastography, measurements of Ep-CAM and cytokeratin-19 before and six months post-treatment. We looked for predictors of recurrence and performed a survival analysis using Kaplan-Meier estimates.

RESULTS

TACE was the most common procedure (77.1%), followed by microwave ablation (15.6%). Complete ablation was achieved in 97 patients; 55 of them developed HCC recurrence. After treatment, LSM increased significantly with a significant reduction in CSCs levels in complete and partial response groups. The median time to observe any recurrence was 14 months. LSM increased significantly post-treatment in patients with recurrence versus no recurrence. Higher levels of CSCs were recorded at baseline and post-treatment in patients with recurrence but without statistical significance. We used univariate analysis to predict the time of recurrence by determining baseline CK-19 and platelet levels as the key factors, while the multivariate analysis determined platelet count as a single factor. The univariate analysis for prediction of overall survival included several factors, LSM and EpCAM (baseline and post-ablation) among them, while multivariate analysis included factors such as Child score B and incomplete ablation.

CONCLUSION

Dynamic changes were observed in LSM and CSCs levels in response to HCC treatment and tumour recurrence. Child score and complete ablation are factors that significantly affect survival.

Murine hepatoblast-derived liver tumors resembling human combined hepatocellular-cholangiocarcinoma with stem cell features

BACKGROUND

Combined hepatocellular-cholangiocarcinoma (CHC) is a primary hepatic malignancy with heterogeneously combined histological features of putative hepatic progenitor cells (HPC) origin. We describe a mouse model that exhibits the heterogenous histological and phenotypic finding similar to human CHC.

METHODS

We injected hepatoblasts isolated from p53-/- C57BL/6 mice into syngeneic wild-type pre-conditioned C57BL/6 mice. We confirmed that p53-/- murine hepatoblasts act as tumor-initiating cells (TICs) that generate CHC both in situ and within metastases. For comparative pathological study, 8 human cases of CHC with stem cell features were recruited by immunohistochemistry and multicolor fluorescence immunostaining.

RESULTS

We identified corresponding areas in murine tumors matching each WHO criteria-described subtype of human CHC. In both murine and human tumors, HPC-like cells in tumor nests and associated stem cell features/traits are suggested histologically to be the progenitor origin of the cancer.

CONCLUSIONS

The pathological characteristics of murine tumors recapitulate human CHC with stem cell features. These data provide additional comparative pathological evidence that CHC with stem cell features originate from HPCs and validate a model to study this cancer type in vivo.

Stem Cell Therapy for Hepatocellular Carcinoma: Future Perspectives

Hepatocellular carcinoma (HCC) is one of the most common types of cancer and results in a high mortality rate worldwide. Unfortunately, most cases of HCC are diagnosed in an advanced stage, resulting in a poor prognosis and ineffective treatment. HCC is often resistant to both radiotherapy and chemotherapy, resulting in a high recurrence rate. Although the use of stem cells is evolving into a potentially effective approach for the treatment of cancer, few studies on stem cell therapy in HCC have been published. The administration of stem cells from bone marrow, adipose tissue, the amnion, and the umbilical cord to experimental animal models of HCC has not yielded consistent responses. However, it is possible to induce the apoptosis of cancer cells, repress angiogenesis, and cause tumor regression by administration of genetically modified stem cells. New alternative approaches to cancer therapy, such as the use of stem cell derivatives, exosomes or stem cell extracts, have been proposed. In this review, we highlight these experimental approaches for the use of stem cells as a vehicle for local drug delivery.

Clinical implications of cancer stem cells in digestive cancers: acquisition of stemness and prognostic impact

Digestive system cancers are the most frequent cancers worldwide and often associated with poor prognosis because of their invasive and metastatic characteristics. Recent studies have found that the plasticity of cancer cells can impart cancer stem-like properties via the epithelial-mesenchymal transition (EMT). Cancer stem-like properties such as tumor initiation are integral to the formation of metastasis, which is the main cause of poor prognosis. Numerous markers of cancer stem cells (CSCs) have been identified in many types of cancer. Therefore, CSCs, via their stem cell-like functions, may play an important role in prognosis after surgery. While several reports have described prognostic analysis using CSC markers, few reviews have summarized CSCs and their association with prognosis. Herein, we review the prognostic potential of eight CSC markers, CD133, CD44, CD90, ALDH1A1, EPCAM, SOX2, SOX9, and LGR5, in digestive cancers including those of the pancreas, colon, liver, gastric, and esophagus.

Splenic serum from portal hypertensive patients enhances liver stem cell proliferation and self-renewal via the IGF-II/ERK signaling pathway

BACKGROUND

Hypersplenism is a serious complication of portal hypertension (PH) and can affect the prognosis of liver disease. Liver stem cells (LSCs) are involved in liver regeneration and hepatocarcinogenesis after liver cirrhosis.

AIM

To explore the effects and mechanism of the spleen on the proliferation and differentiation of LSCs in PH due to liver cirrhosis.

METHODS

Fetal liver stem cells (FLSCs) were treated with splenic serum from liver cirrhosis patients with hypersplenism and control serum from healthy volunteers, and the proliferation, self-renewal, and IGF-II/ERK signaling pathway of FLSCs were then evaluated.

RESULTS

We found that splenic serum from PH patients promoted FLSC proliferation, colony formation, and Ki-67 expression in vitro. Splenic serum from PH also enhanced FLSC spheroid formation in vitro. Mechanistically, we determined that insulin-like growth factor (IGF)-II concentration was elevated in splenic serum from PH patients and could promote FLSC proliferation and self-renewal. Furthermore, both IGF-II and splenic serum from PH patients enhanced ERK signaling activation through IGF-I receptor (IGF-I R) in FLSCs. Consistently, blocking IGF-I R or ERK signaling could attenuate the effects of splenic serum from PH patients on FLSCs.

CONCLUSIONS

The spleen in PH patients promotes FLSC proliferation and self-renewal through the IGF-II/ERK signaling pathway.

Liver Progenitors and Adult Cell Plasticity in Hepatic Injury and Repair: Knowns and Unknowns

The liver is a complex organ performing numerous vital physiological functions. For that reason, it possesses immense regenerative potential. The capacity for repair is largely attributable to the ability of its differentiated epithelial cells, hepatocytes and biliary epithelial cells, to proliferate after injury. However, in cases of extreme acute injury or prolonged chronic insult, the liver may fail to regenerate or do so suboptimally. This often results in life-threatening end-stage liver disease for which liver transplantation is the only effective treatment. In many forms of liver injury, bipotent liver progenitor cells are theorized to be activated as an additional tier of liver repair. However, the existence, origin, fate, activation, and contribution to regeneration of liver progenitor cells is hotly debated, especially since hepatocytes and biliary epithelial cells themselves may serve as facultative stem cells for one another during severe liver injury. Here, we discuss the evidence both supporting and refuting the existence of liver progenitor cells in a variety of experimental models. We also debate the validity of developing therapies harnessing the capabilities of these cells as potential treatments for patients with severe and chronic liver diseases.

Targeting Liver Cancer Stem Cells Using Engineered Biological Nanoparticles for the Treatment of Hepatocellular Cancer

By exploiting their biological functions, the use of biological nanoparticles such as extracellular vesicles can provide an efficient and effective approach for hepatic delivery of RNA‐based therapeutics for the treatment of liver cancers such as hepatocellular cancer (HCC). Targeting liver cancer stem cells (LCSC) within HCC provide an untapped opportunity to improve outcomes by enhancing therapeutic responses. Cells with tumor‐initiating capabilities such as LCSC can be identified by expression of markers such as epithelial cell adhesion molecule (EpCAM) on their cell surface. EpCAM is a target of Wnt/β‐catenin signaling, a fundamental pathway in stem‐cell growth. Moreover, mutations in the β‐catenin gene are frequently observed in HCC and can be associated with constitutive activation of the Wnt/β‐catenin pathway. However, targeting these pathways for the treatment of HCC has been challenging. Using RNA nanotechnology, we developed engineered biological nanoparticles capable of specific and effective delivery of RNA therapeutics targeting β‐catenin to LCSC. Extracellular vesicles isolated from milk were loaded with small interfering RNA to β‐catenin and decorated with RNA scaffolds to incorporate RNA aptamers capable of binding to EpCAM. Cellular uptake of these EpCAM‐targeting therapeutic milk‐derived nanovesicles in vitro resulted in loss of β‐catenin expression and decreased proliferation. The uptake and therapeutic efficacy of these engineered biological nanotherapeutics was demonstrated in vivo using tumor xenograft mouse models. Conclusion: β‐catenin can be targeted directly to control the proliferation of hepatic cancer stem cells using small interfering RNA delivered using target‐specific biological nanoparticles. Application of this RNA nanotechnology–based approach to engineer biological nanotherapeutics provides a platform for developing cell‐surface molecule–directed targeted therapeutics.

Co-delivery of Bmi1 small interfering RNA with ursolic acid by folate receptor-targeted cationic liposomes enhances anti-tumor activity of ursolic acid in vitro and in vivo

Overexpression of Bmi1 gene is an important feature of cancer stem cell in various human tumors. Therefore, Bmi1 gene can be a potential target for small interfering RNA (siRNA) mediated cancer therapy. Ursolic acid (UA) as a natural product plays a pivotal role in anti-tumor field, although its performance is limited by low bioavailability and poor hydrophilicity. A folate receptor-targeted cationic liposome system was designed for the purpose of investigating the relationship between Bmil siRNA and UA. The folate receptor-targeted cationic liposomes co-delivering UA and Bmi1 siRNA (FA-UA/siRNA-L) were fabricated by electrostatic interaction between folate UA liposome (FA-UA-L) and Bmi1 siRNA. Tumor growth is inhibited by FA-UA/siRNA-L in vitro and in vivo and this inhibition is contributed by a synergistic anti-tumor effect of UA and Bmi1 siRNA. The western blot measurement of apoptosis-protein and cancer stem cell (CSC) marked-protein demonstrated that UA led to activation-induced tumor cell death and Bmi1 siRNA resulted in inhibition of cancer stem cells. Overall, these results indicate that Bmi1 as a regulating gene for cancer stem cell is an effective target for cancer treatment using siRNA and co-delivery of UA and Bmi1 siRNA using folate-targeted liposomes is a promising strategy for improved anti-tumor effect.

Role of Cancer Stem Cells in Cholangiocarcinoma and Therapeutic Implications

Cholangiocarcinoma (CCA) is the second most common type of liver cancer, and is highly aggressive with very poor prognosis. CCA is classified into intrahepatic cholangiocarcinoma (iCCA) and extra-hepatic cholangiocarcinoma (eCCA), which is further stratified into perihilar (pCCA) and distal (dCCA). Cancer stem cells (CSCs) are a subpopulation of cancer cells capable of tumor initiation and malignant growth, and are also responsible for chemoresistance. Thus, CSCs play an important role in CCA carcinogenesis. Surface markers such as CD133, CD24, CD44, EpCAM, Sox2, CD49f, and CD117 are important for identifying and isolating CCA CSCs. CSCs are present in the tumor microenvironment (TME), termed ‘CSC niche’, where cellular components and soluble factors interact to promote tumor initiation. Epithelial-to-mesenchymal transition (EMT) is another important mechanism underlying carcinogenesis, involved in the invasiveness, metastasis and chemoresistance of cancer. It has been demonstrated that EMT plays a critical role in generating CSCs. Therapies targeting the surface markers and signaling pathways of CCA CSCs, proteins involved in TME, and immune checkpoint proteins are currently under investigation. Therefore, this review focuses on recent studies on the roles of CSCs in CCA; the possible therapeutic strategies targeting CSCs of CCA are also discussed.

Genome-Wide Mapping of Bivalent Histone Modifications in Hepatic Stem/Progenitor Cells

The "bivalent domain," a distinctive histone modification signature, is characterized by repressive trimethylation of histone H3 at lysine 27 (H3K27me3) and active trimethylation of histone H3 at lysine 4 (H3K4me3) marks. Maintenance and dynamic resolution of these histone marks play important roles in regulating differentiation processes in various stem cell systems. However, little is known regarding their roles in hepatic stem/progenitor cells. In the present study, we conducted the chromatin immunoprecipitation (ChIP) assay followed by high-throughput DNA sequencing (ChIP-seq) analyses in purified delta-like 1 protein (Dlk⁺) hepatic stem/progenitor cells and successfully identified 562 genes exhibiting bivalent domains within 2 kb of the transcription start site. Gene ontology analysis revealed that these genes were enriched in developmental functions and differentiation processes. Microarray analyses indicated that many of these genes exhibited derepression after differentiation toward hepatocyte and cholangiocyte lineages. Among these, 72 genes, including Cdkn2a and Sox4, were significantly upregulated after differentiation toward hepatocyte or cholangiocyte lineages. Knockdown of Sox4 in Dlk⁺ cells suppressed colony propagation and resulted in increased numbers of albumin⁺/cytokeratin 7⁺ progenitor cells in colonies. These findings implicate that derepression of Sox4 expression is required to induce normal differentiation processes. In conclusion, combined ChIP-seq and microarray analyses successfully identified bivalent genes. Functional analyses of these genes will help elucidate the epigenetic machinery underlying the terminal differentiation of hepatic stem/progenitor cells.

Conversion of Stem Cells to Cancer Stem Cells: Undercurrent of Cancer Initiation

Cancer stem cells (CSCs) also known as cancer-initiating cells (CIC), are responsible for the sustained and uncontrolled growth of malignant tumors and are proposed to play significant roles in metastasis and recurrence. Several hypotheses have proposed that the events in either stem and/or differentiated cells, such as genomic instability, inflammatory microenvironment, cell fusion, and lateral gene transfer, should be considered as the possible origin of CSCs. However, until now, the exact origin of CSC has been obscure. The development of induced pluripotent stem cells (iPSCs) in 2007, by Yamanaka's group, has been met with much fervency and hailed as a breakthrough discovery by the scientific and research communities, especially in regeneration therapy. The studies on the development of CSC from iPSCs should also open a new page of cancer research, which will help in designing new therapies applicable to CSCs. Currently most reviews have focused on CSCs and CSC niches. However, the insight into the niche before the CSC niche should also be of keen interest. This review introduces the novel concept of cancer initiation introducing the conversion of iPSCs to CSCs and proposes a relationship between the inflammatory microenvironment and cancer initiation as the key concept of the cancer-inducing niche responsible for the development of CSC.

Targeting glutaminase 1 attenuates stemness properties in hepatocellular carcinoma by increasing reactive oxygen species and suppressing Wnt/beta-catenin pathway

Background

Hepatocellular carcinoma (HCC) is an aggressive malignant disease with poor prognosis. Recent advances suggest the existence of cancer stem cells (CSCs) within liver cancer, which are considered to be responsible for tumor relapse, metastasis, and chemoresistance. However, novel therapeutic approaches for eradicating CSCs are yet to be established. Here, we aimed to identify the role of glutaminase 1 (GLS1) in stemness, and the feasibility that GLS1 serves as a therapeutic target for elimination CSCs as well as the possible mechanism.

Methods

Publicly-available data from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) was mined to unearth the association between GLS1 and stemness phenotype. Using big data, human tissues and multiple cell lines, we gained a general picture of GLS1 expression in HCC progression. We generated stable cell lines by lentiviral-mediated overexpression or CRISPR/Cas9-based knockout. Sphere formation assays and colony formation assays were employed to analyze the relationship between GLS1 and stemness. A series of bioinformatics analyses and molecular experiments including qRT-PCR, immunoblotting, flow cytometry, and immunofluorescence were employed to investigate the role of GLS1 in regulating stemness in vitro and in vivo.

Findings

We observed GLS1 (both KGA and GAC isoform) is highly expressed in HCC, and that high expression of GAC predicts a poor prognosis. GLS1 is exclusively expressed in the mitochondrial matrix. Upregulation of GLS1 is positively associated with advanced clinicopathological features and stemness phenotype. Targeting GLS1 reduced the expression of stemness-related genes and suppressed CSC properties in vitro. We further found GLS1 regulates stemness properties via ROS/Wnt/β-catenin signaling and that GLS1 knockout inhibits tumorigenicity in vivo.

Interpretation

Targeting GLS1 attenuates stemness properties in HCC by increasing ROS accumulation and suppressing Wnt/β-catenin pathway, which implied that GLS1 could serve as a therapeutic target for elimination of CSCs.

Generation and characterization of hepatocellular carcinoma cell lines with enhanced cancer stem cell potential

Hepatocellular carcinoma (HCC) is one of the most common causes for cancer-related death worldwide with rapidly increasing incidence and mortality rates. As for other types of cancers, also in HCC cancer stem cells (CSCs) are thought to be responsible for tumour initiation, progression and therapy failure. However, as rare subpopulations of tumour tissue, CSCs are difficult to isolate, thus making the development of suitable and reliable model systems necessary. In our study, we generated HepG2 subclones with enriched CSC potential by application of the spheroid formation method and subsequent single-cell cloning. Analyses in several 2D and 3D cell culture systems as well as a panel of functional assays both in vitro and in vivo revealed that the generated subclones displayed characteristic and sustained features of tumour initiating cells as well as highly aggressive properties related to tumour progression and metastasis. These characteristics could clearly be correlated with the expression of CSC markers that might have prognostic value in the clinical HCC setting. Therefore, we conclude that our CSC enriched HepG2 clones certainly represent suitable model systems to study the role of CSCs during HCC initiation, progression and drug resistance.

1α,25-Dihydroxyvitamin D3 inhibits aflatoxin B1-induced proliferation and dedifferentiation of hepatic progenitor cells by regulating PI3K/Akt and Hippo pathways

Hepatic progenitor cells (HPCs) might be the origin of hepatocellular carcinoma. 1α,25-Dihydroxyvitamin D3 (1,25(OH)₂D₃) (VD3) has been documented as an anticancer agent for various cancers. However, the potential effect of VD3 on the proliferation and malignant transformation of HPCs induced by aflatoxin B1 (AFB1) has not been determined. In this study, we found that AFB1 exhibited the stimulative effects on the proliferation, dedifferentiation and invasion of HPCs via activating AKT pathway but turning off Hippo pathway, which were terminated when VD3 was used in combination with AFB1. Furthermore, in AFB1-induced liver damage mouse model, VD3 also showed protective effect by reducing HPCs population. Together, these preclinical data not only provide a newly identified mechanism by which AFB1 affects HPCs but also strengthen the idea of developing VD3 as an anticancer agent.

Tumor-associated macrophages recruited by periostin in intrahepatic cholangiocarcinoma stem cells

Periostin (POSTN) secreted by intrahepatic cholangiocarcinoma stem cells (ICSCs) serves important roles in promoting tumor progression. The present study aimed to investigate POSTN-recruited tumor-associated macrophages (TAMs) in intrahepatic cholangiocarcinoma (ICC). A total of 50 cases were used to investigate the distribution of ICSCs and TAMs in ICC. HCCC-9810 cells were sorted by cluster of differentiation (CD)44, the expression of POSTN of CD44⁺ (cancer stem cells) and CD44^- cells (non-cancer stem cells), and medium were evaluated by western blot analysis. HCCC-9810 cells and THP-1 macrophages were used to detect the effects of POSTN on recruiting TAMs in vitro. The present study revealed that CD44⁺ cells in ICC tissues and the HCCC-9810 cell line were associated with high POSTN secretion levels. Furthermore, POSTN was associated with TAM density in primary ICC tissues. Additionally, POSTN increased the migration of TAMs derived from THP-1 cells. These findings suggested that POSTN secreted by ICSCs may serve important functions in TAM recruitment, and it may be a potential curative strategy to target the tumor microenvironment in ICC.

Bufalin suppresses hepatocarcinogenesis by targeting β-catenin/TCF signaling via cell cycle-related kinase

Hepatocellular carcinoma (HCC) is one of the most aggressive malignant tumors, of which treatment options are limited especially in advanced stage. Bufalin, the major digoxin-like component of the traditional Chinese medicine Chansu, exhibits significant antitumor activities in hepatoma cells, but the potential mechanism is obscure. Cell cycle-related kinase (CCRK) is recently identified to be a crucial oncogenic master regulator to drive hepatocarcinogenesis. Here we investigated the molecular function of bufalin on CCRK-regulated signaling pathway, and expounded the underlying mechanism in HCC suppression. In vitro with PLC5 HCC cells and human immortal LO2 cells, proliferation, malignant transformation and cell cycle progression assays were performed to evaluate the antitumor effect of bufalin. In vivo with xenograft and orthotopic mice models, tumor growths with weight and volume change were assessed with or without bufalin treatment. Western blot, RT-qPCR, immunofluorescence and immunohistochemistry were conducted to examine the expression level of CCRK and β-catenin/TCF signaling cascade. We revealed that bufalin suppresses PLC5 HCC cell proliferation, transformation and cell cycle progression rather than LO2 cells, which is correlated with CCRK-mediated β-catenin/TCF signaling. It was also confirmed in mice model. Thus, bufalin is a potential anti-HCC therapeutic candidate through the inhibition of CCRK-driven β-catenin/TCF oncogenic signaling pathway.

Stem-like plasticity and heterogeneity of circulating tumor cells: current status and prospect challenges in liver cancer

Poor prognosis and high recurrence remain leading causes of primary liver cancerassociated mortality. The spread of circulating tumor cells (CTCs) in the blood plays a major role in the initiation of metastasis and tumor recurrence after surgery. Nevertheless, only a subset of CTCs can survive, migrate to distant sites and establish secondary tumors. Consistent with cancer stem cell (CSC) hypothesis, stem-like CTCs might represent a potential source for cancer relapse and distant metastasis. Thus, identification of stem-like metastasis-initiating CTC-subset may provide useful clinically prognostic information. This review will emphasize the most relevant findings of CTCs in the context of stem-like biology associated to liver carcinogenesis. In this view, the emerging field of stem-like CTCs may deliver substantial contribution in liver cancer field in order to move to personalized approaches for diagnosis, prognosis and therapy.

Exosomes from human colorectal cancer induce a tumor-like behavior in colonic mesenchymal stromal cells

Background

Cancer cells, including colorectal cancer ones (CRC), release high amounts of nanovesicles (exosomes), delivering biochemical messages for paracrine or systemic crosstalk. Mesenchymal stromal cells (MSCs) have been shown to play contradicting roles in tumor progression.

Results

CRC exosomes induce in cMSCs: i) atypical morphology, higher proliferation, migration and invasion; ii) formation of spheroids; iii) an acidic extracellular environment associated with iv) a plasma membrane redistribution of vacuolar H+-ATPase and increased expression of CEA. Colon cancer derived MSCs, which were isolated from tumor masses, produce umbilicated spheroids, a future frequently observed in the inner core of rapidly growing tumors and recapitulate the changes observed in normal colonic MSCs exposed to CRC exosomes.

Materials and Methods

Tissue specific colonic (c)MSCs were exposed to primary or metastatic CRC exosomes and analysed by light and electron microscopy, proliferation in 2D and 3D cultures, migration and invasion assays, Western blot and confocal microscopy for vacuolar H+-ATPase expression.

Conclusions

CRC exosomes are able to induce morphological and functional changes in colonic MSCs, which may favour tumor growth and its malignant progression. Our results suggest that exosomes are actively involved in cancer progression and that inhibiting tumor exosome release may represent a way to interfere with cancer.

Differentiation-inducing therapeutic effect of Notch inhibition in reversing malignant transformation of liver normal stem cells via MET

Background

Liver cancer stem cells (LCSCs) are the key factors for cancer metastasis, recurrent, and drug resistance. LCSCs are originated from either hepatocytes dedifferentiation or differentiation arresting of liver normal stem cells (LNSCs). Differentiation-inducing therapy is a novel strategy in solid tumors. Furthermore, Notch signaling pathway has been proved to play important role in the process of hepatocytes differentiation. In previous study, a malignant transformation cellular model of LNSCs has been built up, and in this study we are trying to illustrate whether inhibition of Notch can reverse this malignant tendency and drive these malignant cells back to differentiate into mature hepatocytes.

Results

Inhibition of Notch signaling pathway can down-regulate the stemness-related cancer markers, lower the proliferative status, alleviate the invasive characteristic, or attenuate the metastasis tendency. What is more, it can help the malignantly transformed cells to regain the mature hepatic function of glucagon synthesis, urea metabolism, albumin production, and indocyanine-green (ICG) clearance.

Materials and Methods

HOX transcript antisense RNA (HOTAIR) expression was enhanced in LNSCs via lentivirus transduction to set up the malignant transformation cellular model. Then, a Notch inhibitor was applied to induce malignantly transformed cells differentiate into mature hepatocytes, and malignant abilities of proliferation, invasiveness, tumorigenesis as well as mature hepatocyte function were observed and compared.

Conclusions

The data demonstrate that the anti-tumor effects of Notch inhibition may lie not only on killing the cancer cells or LCSCs directly, it can also induce the LCSCs differentiation into mature hepatocytes via mesenchymal-epithelial transition (MET) progress or downgrade the malignancy.

Chronic inflammation-elicited liver progenitor cell conversion to liver cancer stem cell with clinical significance

The substantial heterogeneity and hierarchical organization in liver cancer support the theory of liver cancer stem cells (LCSCs). However, the relationship between chronic hepatic inflammation and LCSC generation remains obscure. Here, we observed a close correlation between aggravated inflammation and liver progenitor cell (LPC) propagation in the cirrhotic liver of rats exposed to diethylnitrosamine. LPCs isolated from the rat cirrhotic liver initiated subcutaneous liver cancers in nonobese diabetic/severe combined immunodeficient mice, suggesting the malignant transformation of LPCs toward LCSCs. Interestingly, depletion of Kupffer cells in vivo attenuated the LCSC properties of transformed LPCs and suppressed cytokeratin 19/Oval cell 6-positive tumor occurrence. Conversely, LPCs cocultured with macrophages exhibited enhanced LCSC properties. We further demonstrated that macrophage-secreted tumor necrosis factor-α triggered chromosomal instability in LPCs through the deregulation of ubiquitin D and checkpoint kinase 2 and enhanced the self-renewal of LPCs through the tumor necrosis factor receptor 1/Src/signal transducer and activator of transcription 3 pathway, which synergistically contributed to the conversion of LPCs to LCSCs. Clinical investigation revealed that cytokeratin 19/Oval cell 6-positive liver cancer patients displayed a worse prognosis and exhibited superior response to sorafenib treatment.

CONCLUSION

Our results not only clarify the cellular and molecular mechanisms underlying the inflammation-mediated LCSC generation but also provide a molecular classification for the individualized treatment of liver cancer. (Hepatology 2017;66:1934-1951).

Liver Cancer: Molecular Characterization, Clonal Evolution and Cancer Stem Cells

Liver cancer is the second most common cause of cancer-related death. The major forms of primary liver cancer are hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA). Both these tumors develop against a background of cirrhotic liver, non-alcoholic fatty liver disease, chronic liver damage and fibrosis. HCC is a heterogeneous disease which usually develops within liver cirrhosis related to various etiologies: hepatitis B virus (HBV) infection (frequent in Asia and Africa), hepatitis C virus (HCV), chronic alcohol abuse, or metabolic syndrome (frequent in Western countries). In cirrhosis, hepatocarcinogenesis is a multi-step process where pre-cancerous dysplastic macronodules transform progressively into HCC. The patterns of genomic alterations observed in these tumors were recently identified and were instrumental for the identification of potential targeted therapies that could improve patient care. Liver cancer stem cells are a small subset of undifferentiated liver tumor cells, responsible for cancer initiation, metastasis, relapse and chemoresistance, enriched and isolated according to immunophenotypic and functional properties: cell surface proteins (CD133, CD90, CD44, EpCAM, OV-6, CD13, CD24, DLK1, α2δ1, ICAM-1 and CD47); the functional markers corresponding to side population, high aldehyde dehydrogenase (ALDH) activity and autofluorescence. The identification and definition of liver cancer stem cells requires both immunophenotypic and functional properties.

Non-coding RNA in hepatocellular carcinoma: Mechanisms, biomarkers and therapeutic targets

The majority of the human genome is not translated into proteins but can be transcribed into RNA. Even though the resulting non-coding RNAs (ncRNAs) do not encode for proteins, they contribute to diseases such as cancer. Here, we review examples of the functions of ncRNAs in liver cancer and their potential use for the detection and treatment of liver cancer.

The diversity and plasticity of adult hepatic progenitor cells and their niche

The liver is a unique organ for homoeostasis with regenerative capacities. Hepatocytes possess a remarkable capacity to proliferate upon injury; however, in more severe scenarios liver regeneration is believed to arise from at least one, if not several facultative hepatic progenitor cell compartments. Newly identified pericentral stem/progenitor cells residing around the central vein is responsible for maintaining hepatocyte homoeostasis in the uninjured liver. In addition, hepatic progenitor cells have been reported to contribute to liver fibrosis and cancers. What drives liver homoeostasis, regeneration and diseases is determined by the physiological and pathological conditions, and especially the hepatic progenitor cell niches which influence the fate of hepatic progenitor cells. The hepatic progenitor cell niches are special microenvironments consisting of different cell types, releasing growth factors and cytokines and receiving signals, as well as the extracellular matrix (ECM) scaffold. The hepatic progenitor cell niches maintain and regulate stem cells to ensure organ homoeostasis and regeneration. In recent studies, more evidence has been shown that hepatic cells such as hepatocytes, cholangiocytes or myofibroblasts can be induced to be oval cell-like state through transitions under some circumstance, those transitional cell types as potential liver-resident progenitor cells play important roles in liver pathophysiology. In this review, we describe and update recent advances in the diversity and plasticity of hepatic progenitor cell and their niches and discuss evidence supporting their roles in liver homoeostasis, regeneration, fibrosis and cancers.

New Horizons for Precision Medicine in Biliary Tract Cancers

Biliary tract cancers (BTC), including cholangiocarcinoma and gallbladder cancer, are poor-prognosis and low-incidence cancers, although the incidence of intrahepatic cholangiocarcinoma is rising. A minority of patients present with resectable disease but relapse rates are high; benefit from adjuvant capecitabine chemotherapy has been demonstrated. Cisplatin/gemcitabine combination chemotherapy has emerged as the reference first-line treatment regimen; there is no standard second-line therapy. Selected patients may be suitable for liver-directed therapy (e.g., radioembolization or external beam radiation), pending confirmation of benefit in randomized studies. Initial trials targeting the epithelial growth factor receptor and angiogenesis pathways have failed to deliver new treatments. Emerging data from next-generation sequencing analyses have identified actionable mutations (e.g., FGFR fusion rearrangements and IDH1 and IDH2 mutations), with several targeted drugs entering clinical development with encouraging results. The role of systemic therapies, including targeted therapies and immunotherapy for BTC, is rapidly evolving and is the subject of this review.Significance: The authors address genetic drivers and molecular biology from a translational perspective, in an intent to offer a clear view of the recent past, present, and future of BTC. The review describes a state-of-the-art update of the current status and future directions of research and therapy in advanced BTC. Cancer Discov; 7(9); 943-62. ©2017 AACR.

New Horizons for Precision Medicine in Biliary Tract Cancers

Biliary tract cancers (BTC), including cholangiocarcinoma and gallbladder cancer, are poor-prognosis and low-incidence cancers, although the incidence of intrahepatic cholangiocarcinoma is rising. A minority of patients present with resectable disease but relapse rates are high; benefit from adjuvant capecitabine chemotherapy has been demonstrated. Cisplatin/gemcitabine combination chemotherapy has emerged as the reference first-line treatment regimen; there is no standard second-line therapy. Selected patients may be suitable for liver-directed therapy (e.g., radioembolization or external beam radiation), pending confirmation of benefit in randomized studies. Initial trials targeting the epithelial growth factor receptor and angiogenesis pathways have failed to deliver new treatments. Emerging data from next-generation sequencing analyses have identified actionable mutations (e.g., FGFR fusion rearrangements and IDH1 and IDH2 mutations), with several targeted drugs entering clinical development with encouraging results. The role of systemic therapies, including targeted therapies and immunotherapy for BTC, is rapidly evolving and is the subject of this review.Significance: The authors address genetic drivers and molecular biology from a translational perspective, in an intent to offer a clear view of the recent past, present, and future of BTC. The review describes a state-of-the-art update of the current status and future directions of research and therapy in advanced BTC. Cancer Discov; 7(9); 943-62. ©2017 AACR.

Anterior Approach to Improve the Prognosis in HCC Patients Via Decreasing Dissemination of EpCAM+ Circulating Tumor Cells

BACKGROUND

It is supposed that the improvement of prognosis in hepatocellular carcinoma (HCC) patient by anterior approach for liver resection was related to the decreasing hematogenic dissemination of circulating cancer cells.

METHODS

The EpCAM⁺ circulating tumor cells (CTCs) were detected in HCC patients having liver resection with either anterior approach (AA) or conventional approach (CA). The relation of CTCs to the 2-year recurrence and survival after surgery was investigated.

RESULTS

Overall, patients with ≥3.5 CTCs had much higher recurrence rate than those with <3.5 CTCs (62.0 vs. 18.0%, P = 0.001). Less CTCs were detected in AA group than that in CA group (mean, 2.1 vs. 3.0; median, 1.2 vs. 3.5; all P = 0.001). The 2-year recurrence rate in AA group was much lower than in CA group (27.1 vs. 44.9%, P = 0.009). The 2-year survival rate in AA group was much higher than in CA group (83.3 vs. 66.7%, P = 0.001). The CTCs in >5 cm AA group were much less than that in >5 cm CA group (3.7 vs. 2.4, P = 0.002). Moreover, the 2-year recurrence rate in >5 cm AA group was much lower than that in >5 cm CA group (29.2 vs. 54.7%, P = 0.001). Also, the 2-year survival rates in >5 cm AA group were much higher than that in >5 cm CA group (72.9 vs. 49.1%, P = 0.01). By multivariate analysis, CA is one of the independent risk factors for poor prognosis in HCC patients after liver resection.

CONCLUSIONS

Like the liver-directed therapies, AA can reduce the dissemination of CTCs, especially in patients with large-size HCC (>5 cm) and successively improve the early prognosis.

Mammalian-enabled (MENA) protein enhances oncogenic potential and cancer stem cell-like phenotype in hepatocellular carcinoma cells

Mammalian-enabled (MENA) protein is an actin-regulatory protein that influences cell motility and adhesion. It is known to play a role in tumorigenicity of hepatocellular carcinoma (HCC) but the underlying molecular mechanism remains unknown. This study aimed to investigate the oncogenic potential of MENA and its capacity to regulate cancer stem cell (CSC)-like phenotypes in HCC cells. Real-time-PCR and western blot were used to assess mRNA and protein levels of target genes in human HCC tissue specimens and HCC cell lines, respectively. Stable MENA-overexpressing HCC cells were generated from HCC cell lines. Transwell cell migration and colony formation assays were employed to evaluate tumorigenicity. Ectopic expression of MENA significantly enhanced cell migration and colony-forming ability in HCC cells. Overexpression of MENA upregulated several hepatic progenitor/stem cell markers in HCC cells. A high MENA protein level was associated with high mRNA levels of MENA, CD133, cytokeratin 19 (CK19), and epithelial cell adhesion molecule (EpCAM) in human HCC tissues. Overexpression of MENA enhanced epithelial-to-mesenchymal transition (EMT) markers, extracellular signal-regulated kinases (ERK) phosphorylation, and the level of β-catenin in HCC cells. This study demonstrated that overexpression of MENA in HCC cells promoted stem cell markers, EMT markers, and tumorigenicity. These effects may involve, at least partially, the ERK and β-catenin signaling pathways.

Lipopolysaccharide induces the differentiation of hepatic progenitor cells into myofibroblasts via activation of the Hedgehog signaling pathway

Normally, hepatic progenitor cells (HPCs) are activated and differentiate into hepatocytes or bile ductular cells to repair liver damage during liver injury. However, it remains controversial whether the abnormal differentiation of HPCs occurs under abnormal conditions. Lipopolysaccharide (LPS), a component of the microenvironment, promotes liver fibrosis. In the present study, HPCs promoted liver fibrosis in rats following carbon tetrachloride (CCl₄) treatment. Meanwhile, the LPS level in the portal vein was elevated and played a primary role in the fate of HPCs. In vitro, LPS inhibited the hepatobiliary differentiation of HPCs. Concurrently, HPCs co-cultured with LPS for 2 weeks showed a tendency to differentiate into myofibroblasts (MFs). Thus, we conclude that LPS promotes the aberrant differentiation of HPCs into MFs as a third type of descendant. This study provides insight into a novel differentiation fate of HPCs in their microenvironment, and could thus lead to the development of HPCs for treatment methods in liver fibrosis.

Tg737 regulates epithelial-mesenchymal transition and cancer stem cell properties via a negative feedback circuit between Snail and HNF4α during liver stem cell malignant transformation

Determining the origin of liver cancer stem cells is important for treating hepatocellular carcinoma. Tg737 deficiency plays an important role in the malignant transformation of liver stem cells, but the underlying mechanism remains unclear. Here we established a chemical-induced mouse hepatoma model and found that Tg737 and hepatocyte nuclear factor 4-alpha (HNF4α) expression decreased and epithelial-mesenchymal transition (EMT)-related marker expression increased during liver cancer development. To investigate the underlying mechanism, we knocked down Tg737 in WB-F344 (WB) rat hepatic oval cells. Loss of Tg737 resulted in nuclear β-catenin accumulation and activation of the Wnt/β-catenin pathway, which further promoted EMT and the malignant phenotype. XAV939, a β-catenin inhibitor, attenuated WB cell malignant transformation due to Tg737 knockdown. To clarify the relationships of Tg737, the β-catenin pathway, and HNF4α, we inhibited Snail and overexpressed HNF4α after Tg737 knockdown in WB cells and found that Snail and HNF4α comprise a negative feedback circuit. Taken together, the results showed that Tg737 regulates a Wnt/β-catenin/Snail-HNF4α negative feedback circuit, thereby blocking EMT and the malignant transformation of liver stem cells to liver cancer stem cells.