Role of microRNA-regulated cancer stem cells in recurrent hepatocellular carcinoma

Among the most common cancers, hepatocellular carcinoma (HCC) has a high rate of tumor recurrence, tumor dormancy, and drug resistance after initial successful chemotherapy or radiotherapy. A small subset of cancer cells, cancer stem cells (CSCs), exhibit stem cell characteristics and are present in various cancers, including HCC. The dysregulation of microRNAs (miRNAs) often accompanies the occurrence and development of HCC. miRNAs can influence tumorigenesis, progression, recurrence, and drug resistance by regulating CSCs properties, which supports their clinical utility in managing and treating HCC. This review summarizes the regulatory effects of miRNAs on CSCs in HCC with a special focus on their impact on HCC recurrence.     

Role of autophagy in tumorigenesis,metastasis,targeted therapy and drug resistance of hepatocellular carcinoma

Autophagy is a "self-degradative" process and is involved in the maintenance of cellular homeostasis and the control of cellular components by facilitating the clearance or turnover of long-lived or misfolded proteins, protein aggregates, and damaged organelles. Autophagy plays a dual role in cancer, including in tumor progression and tumor promotion, suggesting that autophagy acts as a double-edged sword in cancer cells. Liver cancer is one of the greatest leading causes of cancer death worldwide due to its high recurrence rate and poor prognosis. Especially in China, liver cancer has become one of the most common cancers due to the high infection rate of hepatitis virus. In primary liver cancer, hepatocellular carcinoma (HCC) is the most common type. Considering the perniciousness and complexity of HCC, it is essential to elucidate the function of autophagy in HCC. In this review, we summarize the physiological function of autophagy in cancer, analyze the role of autophagy in tumorigenesis and metastasis, discuss the therapeutic strategies targeting autophagy and the mechanisms of drug-resistance in HCC, and provide potential methods to circumvent resistance and combined anticancer strategies for HCC patients.     

The biology of cancer stem cells and its clinical implication in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a highly malignant tumor with limited treatment options in its advanced state. The molecular mechanisms underlying HCC remain unclear because of the complexity of its multi-step development process. Cancer stem cells (CSCs) are defined as a small population of cells within a tumor that possess the capability for self-renewal and the generation of heterogeneous lineages of cancer cells. To date, there have been two theories concerning the mechanism of carcinogenesis, i.e., the stochastic (clonal evolution) model and the hierarchical (cancer stem cell-driven) model. The concept of the CSC has been established over the past decade, and the roles of CSCs in the carcinogenic processes of various cancers, including HCC, have been emphasized. Previous experimental and clinical evidence indicated the existence of liver CSCs; however, the potential mechanistic links between liver CSCs and the development of HCC in humans are not fully understood. Although definitive cell surface markers for liver CSCs have not yet been found, several putative markers have been identified, which allow the prospective isolation of CSCs from HCC. The identification and characterization of CSCs in HCC is essential for a better understanding of tumor initiation or progression in relation to signaling pathways. These markers could be used along with clinical parameters for the prediction of chemoresistance, radioresistance, metastasis and survival and may represent potential targets for the development of new molecular therapies against HCC. This review describes the current evidence for the existence and function of liver CSCs and discuss the clinical implications of CSCs in patients demonstrating resistance to conventional anti-cancer therapies, as well as clinical outcomes. Such data may provide a future perspective for targeted therapy in HCC.     

The effects of hyperthermia on human hepatocellular carcinoma stem and mature cancer cells

Introduction and objectivesHepatocellular carcinoma (HCC) can recur following radiofrequency ablation and other hyperthermic treatment modalities. Cancer stem cells (CSCs) are a subpopulation of HCC cells that are difficult to eradicate and largely responsible for tumor recurrences. Thus, the principal objective of this study was to determine whether human HCC CSCs are relatively thermal-resistant compared to non-stem or mature cancer cells (MCCs).Materials and methodsEpithelial cell adhesion molecule (EpCAM) positive enriched CSCs and EpCAM⁻ MCCs were derived from a human HCC cell line using fluorescence activated cell sorting. Each cell population was exposed to 65 °C heat for 0–16 min and survival documented at various time points.ResultsCell survival curves were similar in CSC and MCCs throughout the 16 min heat exposure period. Maximum killing was obtained after 12–14 min of heat exposure. Cytoprotective, heat shock proteins-70 (HSP70) and -90 (HSP90) mRNA expression were not disproportionately increased in CSCs.ConclusionsThese results suggest that human HCC CSCs are not more thermal resistant than MCCs and therefore, do not support the hypothesis that HCC recurrences following hyperthermic treatment reflect CSC thermal-resistance.     

Selective tropism of liver stem cells to hepatocellular carcinoma in vivo

AIM： To investigate the selective tropism of liver stem cells to hepatocellular carcinoma （HCC） in an animal model and its feasibility as a vector to deliver therapeutic genes for targeted therapy of HCC.
METHODS： WB-F344, a kind of rat liver stem cell, was infected with recombinant virus to establish a cell line with stable, high-level expressing enhanced green fluorescent protein （EGFP）. An animal model of HCC in Wistar rats was established by implanting HCC cells （CBRH7919） combined with an immunosuppressive drug. EGFP labeled liver stern cells were injected into caudal veins of the animals and distribution was observed at different time points after injection. SDF-1 and c-kit expression in non-tumor liver and tumor tissue were analysed by immunohistochemistry for the relationshiop between the expression and migration of liver stem cells. Furthermore, hepatic stern cells were injected via the portal vein, hepatic artery, caudal vein, or directly into the pericancerous liver tissue, respectively, and effects on migration, localization, and proliferation of the hepatic stern cells within the tumor tissue were observed and analyzed.
RESULTS： Recombinant adenovirus could deliver the EGFP gene to hepatic stem cells. A new stem cell line, named WB-EGFP, was established that stably expressed EGFP. WB-EGFP cells still showed selective tropism towards HCC and EGFP expression was stable in vivo. According to immunohistochemistry results, SDF-1 may not be related to the mechanisms of tropism of hepatic stem cells. Different application sites affected the distribution of liver stem cells. Injection via the portal vein was superior with regard to selective migration, localization, and proliferation of the hepatic stem cells within the tumor tissue.
CONCLUSION： Liver stem cells have the biological behavior of selective migration to HCC in vivo and they could localize and proliferate within HCC tissue stably expressing the target gene. Liver stem cells are a potential tool for a targeted gene therapy o     

Mechanisms of hepatocellular carcinoma and challenges and opportunities for molecular targeted therapy

The incidence and mortality of hepatocellular carcinoma(HCC) have fallen dramatically in China and elsewhere over the past several decades. Nonetheless, HCC remains a major public health issue as one of the most common malignant tumors worldwide and one of the leading causes of death caused by cancer in China. Hepatocarcinogenesis is a very complex biological process associated with many environmental risk factors and factors in heredity, including abnormal activation of cellular and molecular signaling pathways such as Wnt/β-catenin, hedgehog, MAPK, AKT, and ERK signaling pathways, and the balance between the activation and inactivation of the proto-oncogenes and anti-oncogenes, and the differentiation of liver cancer stem cells. Molecule-targeted therapy, a new approach for the treatment of liver cancer, blocks the growth of cancer cells by interfering with the molecules required for carcinogenesis and tumor growth, making it both specific and selective. However, there is no one drug completely designed for liver cancer, and further development in the research of liver cancer targeted drugs is now almost stagnant. The purpose of this review is to discuss recent advances in our understanding of the molecular mechanisms underlying the development of HCC and in the development of novel strategies for cancer therapeutics.     

Second line systemic therapies for hepatocellular carcinoma: Reasons for the failure

Hepatocellular carcinoma(HCC) is the main cause of death in patients with cirrhosis, with an increasing incidence worldwide. Sorafenib is the choice therapy for advanced HCC. Over time several randomized phase Ⅲ trials have been performed testing sunitinib, brivanib, linifanib and other molecules in head-tohead comparison with Sorafenib as first-line treatment for advanced-stage HCC, but none of these has so far been registered in this setting. Moreover, another feared vacuum arises from the absence of molecules registered as second-line therapy for patients who have failed Sorafenib, representing an urgent unmet medical need. To date all molecules tested as second-line therapies for advanced hepatocellular carcinoma, failed to demonstrate an increased survival compared to placebo. What are the possible reasons for the failure? What we should expect in the near future?     

The biological implication of cancer stem cells in hepatocellular carcinoma: a possible target for future therapy

Recent studies indicated the importance of stem cells in cancer, including in hepatocellular carcinoma. The presence of the stem cells and cancer stem cells in liver diseases is associated with the initiation, maintenance, metastasis and chemoresistance. Since hepatocellular carcinoma is a heterogeneous disease with a wide variety of prognostic types, which may limit the efficiency of standardized therapy, the understanding of the source of the cancer, alteration in important molecular signaling pathways and interaction between cancer cells and other cells types will be important in defining future, tailored treatment strategies.     

ADAMTSL5 is an epigenetically activated gene underlying tumorigenesis and drug resistance in hepatocellular carcinoma

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Identification of side population cells in human hepatocellular carcinoma cell lines with stepwise metastatic potentials

Purpose  To identify the side population (SP) cells from four hepatocellular carcinoma (HCC) cell lines with stepwise metastatic potentials. Methods  SP cells were sorted from HCCLM3, MHCC97-H, MHCC97-L and Hep3B by flow cytometry, and then analyzed by differentiation study, clonogenic assay, chemoresistance study and tumorigenicity assay in vivo. The expression of ABCG₂ in SP cells was detected by immunocytochemistry, western blotting and real-time quantitative PCR, respectively. Results  There was significant difference in SP proportion among HCCLM3, MHCC97-H, MHCC97-L and Hep3B (28.7 ± 1.6%, 14.5 ± 0.6%, 4.2 ± 0.4%, 0.9 ± 0.1%, respectively, P < 0.01). All the SP cells showed similar characteristics of self-renewal, high clonogenicity, remarkable chemo-resistance and high expression of ABCG₂. As low as 2,000 SP cells could initiate tumors in non-obese diabetic/severe combined immunodeficiency mice successfully. Conclusions  SP cells purified from HCC cell lines harbors cancer stem cell-like properties, and may be related to the metastatic potentials and therapeutic-resistance of HCC. Guo-Ming Shi and Yang Xu contributed equally to this work. This is an original work by all the authors and no previous presentations, reports, or publications contain any material that appears in the article.     

Zebrafish as a disease model for studying human hepatocellular carcinoma

Liver cancer is one of the world's most common cancers and the second leading cause of cancer deaths. Hepatocellular carcinoma(HCC), a primary hepatic cancer, accounts for 90%-95% of liver cancer cases. The pathogenesis of HCC consists of a stepwise process of liver damage that extends over decades, due to hepatitis, fatty liver, fibrosis, and cirrhosis before developing fully into HCC. Multiple risk factors are highly correlated with HCC, including infection with the hepatitis B or C viruses, alcohol abuse, aflatoxin exposure, and metabolic diseases. Over the last decade, genetic alterations, which include the regulation of multiple oncogenes or tumor suppressor genes and the activation of tumorigenesis-related pathways, have also been identified as important factors in HCC. Recently, zebrafish have become an important living vertebrate model organism, especially for translational medical research. In studies focusing on the biology of cancer, carcinogen induced tumors in zebrafish were found to have many similarities to human tumors. Several zebrafish models have therefore been developed to provide insight into the pathogenesis of liver cancer and the related drug discovery and toxicology, and to enable the evaluation of novel smallmolecule inhibitors. This review will focus on illustrativeexamples involving the application of zebrafish models to the study of human liver disease and HCC, through transgenesis, genome editing technology, xenografts,drug discovery, and drug-induced toxic liver injury.     

Molecular targeted therapy for hepatocellular carcinoma:Current and future

Hepatocellular carcinoma(HCC)is one of the most frequent tumors worldwide.The majority of HCC cases occur in patients with chronic liver disease.Despite regular surveillance to detect small HCC in these patients,HCC is often diagnosed at an advanced stage.Because HCC is highly resistant to conventional systemic therapies,the prognosis for advanced HCC patients remains poor.The introduction of sorafenib as the standard systemic therapy has unveiled a new direction for future research regarding HCC treatment.However,given the limited efficacy of the drug,a need exists to look beyond sorafenib.Many molecular targeted agents that inhibit different pathways involved in hepatocarcinogenesis are under various phases of clinical development,and novel targets are being assessed in HCC.This review aims to summarize the efforts to target molecular components of the signaling pathways that are responsible for the development and progression of HCC and to discuss perspectives on the future direction of research.     

肿瘤干细胞的研究进展

肿瘤干细胞是指肿瘤组织中存在的一小群具有自我更新能力和多向分化潜能的细胞。肿瘤干细胞主宰着肿瘤分化、癌细胞增殖、自我更新及血管形成等诸多方面。如果能够有效抑制肿瘤干细胞,就可以从源头上阻断恶性肿瘤的发生、发展。本文对肿瘤干细胞的起源、肿瘤干细胞学说的发展、肿瘤干细胞与肿瘤异质性、转移和耐药的关系以及针对肿瘤干细胞的治疗策略等方面进行综述,为未来肿瘤的诊断和治疗提供新思路。     

Cancer stem cell markers correlate with early recurrence and survival in hepatocellular carcinoma

AIM:To investigate whether expression of cancer stem cell(CSC)markers is associated with recurrence and survival in hepatocellular carcinoma(HCC)patients.METHODS:A consecutive series of 90 HCC patients who underwent curative hepatectomy between April2007 and April 2009 were analyzed.Of the 90 patients,38(42%)experienced recurrence within two years of surgery.To adjust for baseline differences between this early recurrence group and the other patients,propensity-score matching was used to generate 25 pairs of patients.Immunohistochemistry was used to compare expression of CD133,CD90,and epithelial cell adhesion molecule(EpCAM)in liver tissues from propensity score-matched patients and from 10 healthy adults.Associations of the three markers with HCC,clinicopathological characteristics,early recurrence,and survival time were explored.RESULTS:The expression of all three CSC markers was significantly higher in HCC tissue than in healthy liver tissue(P<0.001 for all).Among the HCC clinicopathology characteristics examined,the absence of tumor capsule was associated with CD133 expression(P=0.005);higher histopathology grade and larger tumor size were associated with CD90 expression(P=0.010 and 0.034,respectively);and elevated serum alpha-fetoprotein levels were associated with EpCAM expression(P=0.021).Expression of CD90 and EpCAM was significantly higher in the early recurrence group than in other patients(P=0.001 and 0.045,respectively),whereas CD133 expression was not significantly different between the two groups(P=0.440).Multivariate analysis identified only CD90 expression as significantly associated with early recurrence.Log-rank analysis identified expression of both CD90 and EpCAM as significantly associated with survival time of HCC patients.Cox regression identified EpCAM expression as an independent predictor of survival time.CONCLUSION:Expression of CD133,CD90,and EpCAM CSC markers may be linked to HCC tumor onset and/or progression.In addition,EpCAM expression is associated with shorter survival time,while CD90 expression is associated with early HCC recurrence.     

Antiviral drug resistance increases hepatocellular carcinoma: A prospective decompensated cirrhosis cohort study

AIM:To study the clinical outcome of antiviral therapy in hepatitis B-related decompensated cirrhotic patients.METHODS:Three hundred and twelve patients with decompensated hepatitis B cirrhosis were evaluated in a prospective cohort.With two years of follow-up,198patients in the group receiving antiviral therapy with nucleos(t)ide analogues and 39 patients in the control group without antiviral treatment were analysed.RESULTS:Among the antiviral treatment patients,162had a complete virological response(CVR),and 36 were drug-resistant(DR).The two-year cumulative incidence of hepatocellular carcinoma(HCC)in the DR patients(30.6%)was significantly higher than that in both the CVR patients(4.3%)and the control group(10.3%)(P<0.001).Among the DR patients in particular,the incidence of HCC was 55.6%(5/9)in those who failed rescue therapy,which was extremely high.The rtA181T mutation was closely associated with rescue therapy failure(P=0.006).The Child-Pugh scores of the CVR group were significantly decreased compared with the baseline(8.9±2.3 vs 6.0±1.3,P=0.043).CONCLUSION:This study showed that antiviral drug resistance increased the risk of HCC in decompensated hepatitis B-related cirrhotic patients,especially in those who failed rescue therapy.     

Liver cancer stem cell markers: Progression and therapeutic implications

Cancer stem cells(CSCs) are a small subpopulation in cancer, have been proposed to be cancer-initiating cells, and have been shown to be responsible for chemotherapy resistance and cancer recurrence. The identification of CSC subpopulations inside a tumor presents a new understanding of cancer development because it implies that tumors can only be eradicated by targeting CSCs. Although advances in liver cancer detection and treatment have increased the possibility of curing the disease at early stages, unfortunately, most patients will relapse and succumb to their disease. Strategies aimed at efficiently targeting liver CSCs are becoming important for monitoring the progress of liver cancer therapy and for evaluating new therapeutic approaches. Herein, we provide a critical discussion of biological markers described in the literature regarding liver cancer stem cells and the potential of these markers to serve as therapeutic targets.     

Antiviral therapies for hepatitis B virus-related hepatocellular carcinoma

Chronic hepatitis B virus(HBV) infection is a critical risk factor for the carcinogenesis and progression of hepatocellular carcinoma(HCC). It promotes HCC development by inducing liver fibrogenesis, genetic and epigenetic alterations, and the expression of active viral-coded proteins. Effective antiviral treatments inhibit the replication of HBV, reduce serum viral load and accelerate hepatitis B e antigen serum conversion. Timely initiation of antiviral treatment is not only essential for preventing the incidence of HCC in chronic hepatitis B patients, but also important for reducing HBV reactivation, improving liver function, reducing or delaying HCC recurrence, and prolonging overall survival of HBV-related HCC patients after curative and palliative therapies. The selection of antiviral drugs, monitoring of indicators such as HBV DNA and hepatitis B surface antigen, and timely rescue treatment when necessary, are essential in antiviral therapies for HBVrelated HCC.     

Circulating tumor and cancer stem cells in hepatitis C virus-associated liver disease

AIM: To assess the role of circulating tumor cells (CTCs) and cancer stem cells (CSCs) in hepatitis C virus (HCV)-associated liver disease.METHODS: Blood and/or tissue samples were obtained from HCV (genotype 4)-associated hepatocellular carcinoma patients (HCC; n = 120), chronic hepatitis C patients (CH; n = 30) and 33 normal control subjects (n = 33). Serum levels of alpha-fetoprotein (AFP), alkaline phosphatase, and alanine and aspartate aminotransferases were measured. Cytokeratin 19 (CK19) monoclonal antibody was used to enumerate CTCs, and CD133 and CD90 were used to enumerate CSCs by flow cytometry. The expression levels of the CSCs markers (CD133 and CD90) as well as telomerase, melanoma antigen encoding gene 1 (MAGE1) and MAGE3 were assessed by RT-PCR and quantitative real-time polymerase chain reactions. The number of CTCs and/or the expression levels of CK19, CD133, telomerase, MAGE1 and MAGE3 were correlated to the standard clinicopathologic prognostic factors and disease progression.RESULTS: Levels of AFP, alkaline phosphatase and aspartate aminotransferase were significantly different among the HCC, CH and control groups (P < 0.001), whereas alanine aminotransferase differed significantly between patient (HCC and CH) and control groups (P < 0.001). At the specified cutoff values determine by flow cytometry, CK19 (49.8), CD90 (400) and CD133 (73) were significantly higher in the blood of HCC patients compared to those in the CH and control groups (P < 0.001). On the other hand, CD133 at a 69.5 cutoff was significantly higher in the CH compared to the control group (P ≤ 0.001). Telomerase, MAGE1 and MAGE3 RNA were expressed in 55.71%, 60.00% and 62.86% of the HCC patients, respectively, but were not detected in patients in the CH or control groups, which were statistically significant (Ps < 0.001). The expression levels of telomerase, CD90, MAGE3, CD133 and CK19 were all significantly associated with high tumor grade and advanced stage in HCC patients (all Ps < 0.05).CONCLUSION: CTC counts and AFP, CK19, telomerase, and MAGE1/MAGE3 expression predict disease progression in patients with HCV, whereas telomerase, MAGE3, CD90, CD133 and CK19 are prognostic markers in HCC.     

胰腺癌干细胞的研究进展

胰腺癌是恶性程度极高的消化道肿瘤,是全球癌症相关性死亡的主要原因之一.由于发病机制尚不明确,早期缺乏特征性临床表现及诊断方法,且传统治疗效果欠佳,导致胰腺癌的发病率及死亡率居高不下.近年来,随着干细胞在多个领域研究的不断推进,胰腺癌干细胞(pancreatic cancer stem cells,PCSCs)在胰腺癌发...