Invasion and EMT-associated genes are up-regulated in B viral hepatocellular carcinoma with high expression of CD133-human and cell culture study

Modulation of Cellular Function by the Urokinase Receptor Signalling: A Mechanistic View

Urokinase-type plasminogen activator receptor (uPAR or CD87) is a glycosyl-phosphatidyl-inositol anchored (GPI) membrane protein. The uPAR primary ligand is the serine protease urokinase (uPA), converting plasminogen into plasmin, a broad spectrum protease, active on most extracellular matrix components. Besides uPA, the uPAR binds specifically also to the matrix protein vitronectin and, therefore, is regarded also as an adhesion receptor. Complex formation of the uPAR with diverse transmembrane proteins, including integrins, formyl peptide receptors, G protein-coupled receptors and epidermal growth factor receptor results in intracellular signalling. Thus, the uPAR is a multifunctional receptor coordinating surface-associated pericellular proteolysis and signal transduction, thereby affecting physiological and pathological mechanisms. The uPAR-initiated signalling leads to remarkable cellular effects, that include increased cell migration, adhesion, survival, proliferation and invasion. Although this is beyond the scope of this review, the uPA/uPAR system is of great interest to cancer research, as it is associated to aggressive cancers and poor patient survival. Increasing evidence links the uPA/uPAR axis to epithelial to mesenchymal transition, a highly dynamic process, by which epithelial cells can convert into a mesenchymal phenotype. Furthermore, many reports indicate that the uPAR is involved in the maintenance of the stem-like phenotype and in the differentiation process of different cell types. Moreover, the levels of anchor-less, soluble form of uPAR, respond to a variety of inflammatory stimuli, including tumorigenesis and viral infections. Finally, the role of uPAR in virus infection has received increasing attention, in view of the Covid-19 pandemics and new information is becoming available. In this review, we provide a mechanistic perspective, via the detailed examination of consolidated and recent studies on the cellular responses to the multiple uPAR activities.

The role of CD133 in hepatocellular carcinoma

Cancer stem cells (CSCs) represent a small subpopulation of cells found within tumors that exhibit properties of self-renewal, like normal stem cells. CSCs have been defined as a crucial factor involved in driving cancer relapse, chemoresistance and metastasis. Prominin-1 (CD133) is one of the most well-characterized markers of CSCs in various tumor types, including hepatocellular carcinoma (HCC). CD133+ cells have been demonstrated to be involved in metastasis, tumorigenesis, tumor recurrence, and resistance to treatment in HCC. CD133-related clinical prognosis prediction, and targeted therapy have highlighted the clinical significance of CD133 in HCC. However, there remains controversy over the role of CD133 in experimental and clinical research involving HCC. In this article, we summarize the fundamental cell biology of CD133 in HCC cells and discuss the important characteristics of CD133+ in HCC cells. Furthermore, the prognostic value of CD133, and therapeutic strategies for its targeting in HCC, is also reviewed.

Sirolimus and MMF are insufficient immunosuppressants for regulation of the proliferation of CD133+EpCAM+ cell populations in HCC cell lines

Studies on effective immunosuppressive strategies for the management of patients undergoing a liver transplantation (LT) due to hepatocellular carcinoma (HCC) are limited. In the present study, immunosuppressive candidates predicted to exhibit beneficial immunosuppressive and tumor-suppressive effects in patients with HCC were assessed using Huh7 and HEP3B HCC cells, which have high proportions of CD133+EpCAM+ cancer stem cell (CSC) populations. The immunosuppressants assessed were sirolimus, tacrolimus, cyclosporine A and mycophenolate mofetil (MMF), and their activities were assessed on CSCs. Sirolimus and MMF reduced the proliferation of Huh7 and HEP3B cells; however, the proportion of CD133+EpCAM+ was notably increased in treated Huh7 cells. Sirolimus treatment alone resulted in G0-G1 cell cycle arrest at all doses in all Huh7 and CD133-EpCAM- populations; however, CD133+EpCAM+ populations showed only slight G1 arrest at higher doses only. In contrast, S-phase arrest was induced at all doses in the Huh7, CD133-EpCAM- and CD133+EpCAM+ populations by MMF. Sirolimus and MMF effectively reduced the proliferation of Huh7 and HEP3B cells, but did not exert a notable effect on the CD133+EpCAM+ cells. Therefore, therapeutic strategies utilizing Sirolimus and MMF should be further studied in vivo for regulation of CSC populations in order to reduce HCC recurrence rates.

Metabolic Reprogramming and Epithelial-Mesenchymal Plasticity: Opportunities and Challenges for Cancer Therapy

Metabolic reprogramming and epithelial-mesenchymal plasticity are both hallmarks of the adaptation of cancer cells for tumor growth and progression. For metabolic changes, cancer cells alter metabolism by utilizing glucose, lipids, and amino acids to meet the requirement of rapid proliferation and to endure stressful environments. Dynamic changes between the epithelial and mesenchymal phenotypes through epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET) are critical steps for cancer invasion and metastatic colonization. Compared to the extensively studied metabolic reprogramming in tumorigenesis, the metabolic changes in metastasis are relatively unclear. Here, we review metabolic reprogramming, epithelial-mesenchymal plasticity, and their mutual influences on tumor cells. We also review the developing treatments for targeting cancer metabolism and the impact of metabolic targeting on EMT. In summary, understanding the metabolic adaption and phenotypic plasticity will be mandatory for developing new strategies to target metastatic and refractory cancers that are intractable to current treatments.

Models for Understanding Resistance to Chemotherapy in Liver Cancer

The lack of response to pharmacological treatment constitutes a substantial limitation in the handling of patients with primary liver cancers (PLCs). The existence of active mechanisms of chemoresistance (MOCs) in hepatocellular carcinoma, cholangiocarcinoma, and hepatoblastoma hampers the usefulness of chemotherapy. A better understanding of MOCs is needed to develop strategies able to overcome drug refractoriness in PLCs. With this aim, several experimental models are commonly used. These include in vitro cell-free assays using subcellular systems; studies with primary cell cultures; cancer cell lines or heterologous expression systems; multicellular models, such as spheroids and organoids; and a variety of in vivo models in rodents, such as subcutaneous and orthotopic tumor xenografts or chemically or genetically induced liver carcinogenesis. Novel methods to perform programmed genomic edition and more efficient techniques to isolate circulating microvesicles offer new opportunities for establishing useful experimental tools for understanding the resistance to chemotherapy in PLCs. In the present review, using three criteria for information organization: (1) level of research; (2) type of MOC; and (3) type of PLC, we have summarized the advantages and limitations of the armamentarium available in the field of pharmacological investigation of PLC chemoresistance.

Role of Metabolic Reprogramming in Epithelial⁻Mesenchymal Transition (EMT)

Activation of epithelial–mesenchymal transition (EMT) is thought to be an essential step for cancer metastasis. Tumor cells undergo EMT in response to a diverse range of extra- and intracellular stimulants. Recently, it was reported that metabolic shifts control EMT progression and induce tumor aggressiveness. In this review, we summarize the involvement of altered glucose, lipid, and amino acid metabolic enzyme expression and the underlying molecular mechanisms in EMT induction in tumor cells. Moreover, we propose that metabolic regulation through gene-specific or pharmacological inhibition may suppress EMT and this treatment strategy may be applied to prevent tumor progression and improve anti-tumor therapeutic efficacy. This review presents evidence for the importance of metabolic changes in tumor progression and emphasizes the need for further studies to better understand tumor metabolism.

Molecular bases of the poor response of liver cancer to chemotherapy

A characteristic shared by most frequent types of primary liver cancer, i.e., hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA) in adults, and in a lesser extent hepatoblastoma (HB) mainly in children, is their high refractoriness to chemotherapy. This is the result of synergic interactions among complex and diverse mechanisms of chemoresistance (MOC) in which more than 100 genes are involved. Pharmacological treatment, although it can be initially effective, frequently stimulates the expression of MOC genes, which results in the relapse of the tumor, usually with a more aggressive and less chemosensitive phenotype. Identification of the MOC genetic signature accounting for the "resistome" present at each moment of tumor life would prevent the administration of chemotherapeutic regimens without chance of success but still with noxious side effects for the patient. Moreover, a better description of cancer cells strength is required to develop novel strategies based on pharmacological, cellular or gene therapy to overcome liver cancer chemoresistance.

miR-9a mediates the role of Lethal giant larvae as an epithelial growth inhibitor in Drosophila

Drosophila lethal giant larvae (lgl) encodes a conserved tumor suppressor with established roles in cell polarity, asymmetric division, and proliferation control. Lgl's human orthologs, HUGL1 and HUGL2, are altered in human cancers, however, its mechanistic role as a tumor suppressor remains poorly understood. Based on a previously established connection between Lgl and Fragile X protein (FMRP), a miRNA-associated translational regulator, we hypothesized that Lgl may exert its role as a tumor suppressor by interacting with the miRNA pathway. Consistent with this model, we found that lgl is a dominant modifier of Argonaute1 overexpression in the eye neuroepithelium. Using microarray profiling we identified a core set of ten miRNAs that are altered throughout tumorigenesis in Drosophila lgl mutants. Among these are several miRNAs previously linked to human cancers including miR-9a, which we found to be downregulated in lgl neuroepithelial tissues. To determine whether miR-9a can act as an effector of Lgl in vivo, we overexpressed it in the context of lgl knock-down by RNAi and found it able to reduce the overgrowth phenotype caused by Lgl loss in epithelia. Furthermore, cross-comparisons between miRNA and mRNA profiling in lgl mutant tissues and human breast cancer cells identified thrombospondin (tsp) as a common factor altered in both fly and human breast cancer tumorigenesis models. Our work provides the first evidence of a functional connection between Lgl and the miRNA pathway, demonstrates that miR-9a mediates Lgl's role in restricting epithelial proliferation, and provides novel insights into pathways controlled by Lgl during tumor progression.

Summary: Mir-9a overexpression can suppress the overgrowth phenotype caused by Lgl knock-down in epithelia. Gene profiling identifies pathways dysregulated in lgl mutants and shared features between flies and human cancer cells.

Thalidomide inhibits proliferation and epithelial-mesenchymal transition by modulating CD133 expression in pancreatic cancer cells

Pancreatic cancer is a solid malignancy with a high mortality rate, on account of the high incidence of metastasis at the time of detection. The aggressiveness of pancreatic cancer may be partly driven by cancer stem cells (CSCs), which are characterized by the ability to self-renew and recapitulate tumors in the ectopic setting. However, although a number of drugs targeting CSCs are currently under clinical investigation, few effective drugs have been developed. The present study demonstrated that thalidomide inhibited cell proliferation and metastasis in pancreatic cancer cell lines through the inhibition of epithelial mesenchymal transition. The effect of thalidomide was more pronounced in cluster of differentiation 133 (CD133)⁺ SW1990 cells than in Capan-2 cells, in which CD133 expression was almost undetectable. The results revealed that CD133 is likely to serve a role in the antitumor effect of thalidomide and indicated that thalidomide could be developed as a CSC-specific adjuvant chemotherapy in pancreatic cancer.

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

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

Upregulated long non-coding RNA LOC90784 promotes cell proliferation and invasion and is associated with poor clinical features in HCC

A growing amount of literature has indicated that long non-coding RNAs (lncRNAs) are important factors in hepatocellular carcinoma (HCC) progression. However, the significance of lncRNAs in the progression and prognosis of liver cancer is largely unknown. In the present study, upregulated lncRNA LOC90784 was identified through integrative analysis of GSE58043 and GSE55191. Furthermore, associations between LOC90784 expression and the clinicopathological characteristics of patients were analyzed with a validated cohort 1 and the Cancer Genome Atlas (TCGA) cohort 2. We investigated the mechanisms by which this highly expressed lncRNA promotes HCC proliferation, invasion and migration via qRT-PCR, fluorescence in situ hybridization (FISH) staining, siRNA transfection, cell proliferation assays, Transwell and colony formation assays, flow cytometry analysis and Western blot. The results showed that LOC90784 expression levels were significantly higher in HCC cell lines and tissues and mainly localized in the cytoplasm. Knockdown of lncRNA LOC90784 expression inhibited proliferation and induced apoptosis and cell cycle arrest by promoting Bax and repressing CDK4 and Cyclin D1 protein expression; it also inhibited invasion and migration by repressing MMP2 and MMP9 expression in HCC cells. LOC90784 overexpression was associated with poor clinical features in the two cohorts and poor overall survival rates in HCC patients with clear resection margins (R0) in cohort 2. These results indicated that LOC90784 upregulation may be a critical oncogene and potential new biomarker in HCC.

Vasculogenic mimicry is associated with increased tumor-infiltrating neutrophil and poor outcome in esophageal squamous cell carcinoma

Purpose

Vasculogenic mimicry (VM) is known to be a mechanism to nourish the tumor, but little is known about its prognostic significance in esophageal squamous cell carcinoma (ESCC). We characterized the predictive relevance of VM expression and tumor-infiltrating neutrophil (TIN) density in patients with resectable ESCC.

Methods

We retrospectively collected clinicopathologic characteristics of 117 esophageal cancer (EC) patients undergoing complete resection and without preoperative therapy. Immunohistochemistry was used to detect the expression of E-cadherin and CD66b. CD34/periodic acid-schiff (PAS) double staining was used to detect the expression of VM.

Results

VM expression was observed in 56 (47.9%) patients. VM was negatively correlated with E-cadherin (correlation coefficient =−0.364, P<0.001) and was positively correlated with infiltration of CD66b neutrophil (correlation coefficient =0.421, P<0.001). VM and CD66b⁺ neutrophil infiltration are important markers for poor overall survival and disease-free survival. Multivariate analysis showed that VM, CD66b⁺ neutrophil infiltration, pathologic tumor node metastasis (TNM) (pTNM) stage, and tumor differentiation are significant independent prognostic predictors in ECs (P=0.001, 0.025, 0.001, 0.011, respectively). VM expression is identified in ~47.9% of ESCC, and it is associated with poor outcome and increased TIN.

Conclusion

TIN is an important factor for VM formation. Therefore, studies of invasive ability of EC in patients with VM could supply significant information for therapeutic strategy.

GABPA predicts prognosis and inhibits metastasis of hepatocellular carcinoma

Background

Increasing evidence indicates that abnormal expression of GABPA is associated with tumor development and progression. However, the function and clinicopathological significance of GABPA in hepatocellular carcinoma (HCC) remain obscure.

Methods

The mRNA and protein expression of GABPA in HCC clinical specimens and cell lines was examined by real-time PCR and western blotting, respectively. Follow-up data were used to uncover the relationship between GABPA expression and the prognosis of HCC patients. HCC cell lines stably overexpressing or silencing GABPA were established to explore the function of GABPA in HCC cell migration and invasion by Transwell and wound healing assays in vitro and in a xenograft model in vivo. Restoration of function analysis was used to examine the underlying molecular mechanisms.

Results

GABPA was downregulated at the protein and mRNA levels in HCC tissues compared with adjacent normal tissues. Decreased GABPA expression was correlated with alpha-fetoprotein levels (P = 0.001), tumor grade (P = 0.017), and distant metastasis (P = 0.021). Kaplan-Meier survival analysis showed that patients with lower GABPA expression had significantly shorter survival times than those with higher GABPA (P = 0.031). In vivo and in vitro assays demonstrated that GABPA negatively regulated HCC cell migration and invasion, and the effect of GABPA on HCC cell migration was mediated at least partly by the regulation of E-cadherin.

Conclusions

Collectively, our data indicate that GABPA inhibits HCC cell migration by modulating E-cadherin and could serve as a novel biomarker for HCC prognosis. GABPA may act as a tumor suppressor during HCC progression and metastasis, and is a potential therapeutic target in HCC.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3373-7) contains supplementary material, which is available to authorized users.

Hepatoma cell functions modulated by NEK2 are associated with liver cancer progression

NEK2 (NIMA-related expressed kinase 2) is a serine/threonine centrosomal kinase that acts as a critical regulator of centrosome structure and function. Aberrant NEK2 activities lead to failure in regulating centrosome duplication. NEK2 overexpression promotes tumorigenesis and is associated with poor prognosis in several cancers. Increased NEK2 expression during the late pathological stage has been detected in the Oncomine liver dataset and hepatocellular carcinoma (HCC) specimens. Elevated NEK2 protein is associated with poor overall survival in patients with HCC. However, the precise roles and mechanisms of NEK2 in liver cancer progression remain largely unknown. An earlier functional study revealed that NEK2 mediates drug resistance (cisplatin or lipo-doxorubicin) via expression of an ABCC10 transporter. Active angiogenesis and metastasis underlie the rapid recurrence and poor survival of HCC. Results from the current study showed that NEK2 mediates tumor growth, metastasis and angiogenesis in vivo. NEK2-mediated drug resistance was blocked by a specific PI3K or AKT inhibitor. Moreover, NEK2 mediated liver cancer cell migration via pAKT/NF-κB signaling and matrix metalloproteinase (MMP) activation. Angiogenesis was induced via the same signaling pathway and IL-8 stimulation. Our findings collectively indicate that NEK2 modulates hepatoma cell functions, including growth, drug resistance, metastasis and angiogenesis via downstream genes activation.

Acquisition of anticancer drug resistance is partially associated with cancer stemness in human colon cancer cells

Colorectal cancer (CRC) is one of the most aggressive cancers worldwide. Several anticancer agents are available to treat CRC, but eventually cancer relapse occurs. One major cause of chemotherapy failure is the emergence of drug-resistant tumor cells, suspected to originate from the stem cell compartment. The aim of this study was to ask whether drug resistance was associated with the acquisition of stem cell-like properties. We isolated drug-resistant derivatives of two human CRC cell lines, HT29 and HCT116, using two anticancer drugs with distinct modes of action, oxaliplatin and docetaxel. HT29 cells resistant to oxaliplatin and both HT29 and HCT116 cells resistant to docetaxel were characterized for their expression of genes potentially involved in drug resistance, cell growth and cell division, and by surveying stem cell-like phenotypic traits, including marker genes, the ability to repair cell-wound and to form colonospheres. Among the genes involved in platinum or taxane resistance (MDR1, ABCG2, MRP2 or ATP7B), MDR1 was uniquely overexpressed in all the resistant cells. An increase in the cyclin-dependent kinase inhibitor p21, in cyclin D1 and in CD26, CD166 cancer stem cell markers, was noted in the resistant cells, together with a higher ability to form larger and more abundant colonospheres. However, many phenotypic traits were selectively altered in either HT29- or in HCT116-resistant cells. Expression of EPHB2, ITGβ-1 or Myc was specifically increased in the HT29-resistant cells, whereas only HCT116-resistant cells efficiently repaired cell- wounds. Taken together, our results show that human CRC cells selected for their resistance to anticancer drugs displayed a few stem cell characteristics, a small fraction of which was shared between cell lines. The occurrence of marked phenotypic differences between HT29- and HCT116-drug resistant cells indicates that the acquired resistance depends mostly on the parental cell characteristics, rather than on the drug type used.

The relationship between vasculogenic mimicry and epithelial-mesenchymal transitions

Vasculogenic mimicry (VM) is a vascular‐like structure which can mimic the embryonic vascular network pattern to nourish the tumour tissue. As a unique perfusion way, VM is correlated with tumour progression, invasion, metastasis and lower 5‐year survival rate. Notably, epithelial‐mesenchymal transition (EMT) regulators and EMT‐related transcription factors are highly up‐regulated in VM‐forming tumour cells, which demonstrated that EMT may play a crucial role in VM formation. Therefore, the up‐regulation of EMT‐associated adhesion molecules and other factors can also make a contribution in VM‐forming process. Depending on these discoveries, VM and EMT can be utilized as therapeutic target strategies for anticancer therapy. The purpose of this article is to explore the advance research in the relationship of EMT and VM and their corresponding mechanisms in tumorigenesis effect.

Pygopus-2 promotes invasion and metastasis of hepatic carcinoma cell by decreasing E-cadherin expression

Pygopus-2 over-expression has been reported in several malignancies, such as ovarian, breast, lung and liver cancers. Here we demonstrated that down-regulation of Pygopus-2 by shRNA inhibited hepatic carcinoma cell invasion in vitro and metastasis in xenograft tumor models, which were promoted when Pygopus-2 was over-expressed. Pygopus-2 increased hepatic carcinoma cell invasion and metastasis, by decreasing E-cadherin. Pygopus-2 could bind to the E-cadherin promoter, increasing its methylation, and also indirectly decreased zeb2 expression. In turn these effects caused down-regulation of E-cadherin, potentiating invasion and metastasis. We suggest that targeting Pygopus-2 may potentially inhibit metastasis of hepatic carcinoma.

Prolonged and repetitive exposure to Porphyromonas gingivalis increases aggressiveness of oral cancer cells by promoting acquisition of cancer stem cell properties

Periodontitis is the most common chronic inflammatory condition occurring in the human oral cavity, but our knowledge on its contribution to oral cancer is rather limited. To define crosstalk between chronic periodontitis and oral cancer, we investigated whether Porphyromonas gingivalis, a major pathogen of chronic periodontitis, plays a role in oral cancer progression. To mimic chronic irritation by P. gingivalis in the oral cavity, oral squamous cell carcinoma (OSCC) cells were infected with P. gingivalis twice a week for 5 weeks. Repeated infection of oral cancer cells by P. gingivalis resulted in morphological changes of host cancer cells into an elongated shape, along with the decreased expression of epithelial cell markers, suggesting acquisition of an epithelial-to-mesenchymal transition (EMT) phenotype. The prolonged exposure to P. gingivalis also promoted migratory and invasive properties of OSCC cells and provided resistance against a chemotherapeutic agent, all of which are described as cellular characteristics undergoing EMT. Importantly, long-term infection by P. gingivalis induced an increase in the expression level of CD44 and CD133, well-known cancer stem cell markers, and promoted the tumorigenic properties of infected cancer cells compared to non-infected controls. Furthermore, increased invasiveness of P. gingivalis-infected OSCC cells was correlated with enhanced production of matrix metalloproteinase (MMP)-1 and MMP-10 that was stimulated by interleukin-8 (IL-8) release. This is the first report demonstrating that P. gingivalis can increase the aggressiveness of oral cancer cells via epithelial-mesenchymal transition-like changes and the acquisition of stemness, implicating P. gingivalis as a potential bacterial risk modifier.

Decaprenyl diphosphate synthase subunit 2 as a prognosis factor in hepatocellular carcinoma

AIM: To investigate the involvement of decaprenyl diphosphate synthase subunit 2 (PDSS2) in development and progression of human hepatocellular carcinoma (HCC).

METHODS: PDSS2 protein expression was examined in well- and poorly differentiated HCC tumor samples. The levels of PDSS2 expression were compared with clinical features and prognosis of HCC patients. The effects of PDSS2 on cell proliferation, cell cycle, apoptosis, cell migration, and invasion in HCC HepG2 cells were also investigated.

RESULTS: PDSS2 was downregulated in poorly differentiated cancer samples compared with well-differentiated tumor samples, and the expression level was markedly lower in HCC tissues than in histologically normal tissue adjacent to the cancer. Reduced protein expression was negatively associated with the status of HCC progression. In addition, overexpression of PDSS2 dramatically suppressed cell proliferation and colony formation, and induced apoptosis in HepG2 cells by inducing G1-phase cell-cycle arrest. The migration and invasion capabilities of HepG2 cells were significantly decreased following PDSS2 overexpression.

CONCLUSION: Decreased PDSS2 expression is an unfavorable prognostic factor for HCC, and PDSS2 has potent anticancer activity in HCC tissues and HepG2 cells.

HOXB9 promotes epithelial-to-mesenchymal transition via transforming growth factor-β1 pathway in hepatocellular carcinoma cells

The function of the epithelial-to-mesenchymal transition (EMT) during hepatocellular carcinoma (HCC) progression is well established. However, the regulatory mechanisms modulating this phenomenon remain unclear. Homeobox B9 (HOXB9) has been proposed as an oncogene in many cancer developments, but its function and underlying mechanisms in HCC metastasis remain unknown. HOXB9 modulates EMT through the transforming growth factor-β1 (TGF-β1) pathway, which is a recognized regulator of EMT in HCC cells. The knockdown of HOXB9 decreased the migration and invasion of HCC cells. Conversely, the HOXB9 overexpression led to an increase in the above-mentioned phenotypes in HCC cells. Further analysis of HOXB9-regulated cellular functions showed the ability of this transcription factor to induce EMT. Moreover, we demonstrated that the TGF-β1 pathway is important in HOXB9-induced EMT in HCC cells. These findings define a novel cellular mechanism regulated by HOXB9, which controls EMT phenotype in HCC. This study is the first to illustrate the pivotal function of HOXB9 in regulating the metastatic behavior of HCC cells.

Epithelial-mesenchymal transition: molecular pathways of hepatitis viruses-induced hepatocellular carcinoma progression

Hepatocellular carcinoma is the fifth most common tumor and the third cause of death for cancer in the world. Among the main causative agents of this tumor is the chronic infection by hepatitis viruses B and C, which establish a context of chronic inflammation degenerating in fibrosis, cirrhosis, and, finally, cancer. Recent findings, however, indicate that hepatitis viruses are not only responsible for cancer onset but also for its progression towards metastasis. Indeed, they are able to promote epithelial-mesenchymal transition, a process of cellular reprogramming underlying tumor spread. In this manuscript, we review the currently known molecular mechanisms by which hepatitis viruses induce epithelial-mesenchymal transition and, thus, hepatocellular carcinoma progression.

The synergistic in vitro and in vivo antitumor effect of combination therapy with salinomycin and 5-fluorouracil against hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the few cancers in which a continuous increase in incidence has been observed over several years. Drug resistance is a major problem in the treatment of HCC. In the present study, we used salinomycin (Sal) and 5-fluorouracil (5-FU) combination therapy on HCC cell lines Huh7, LM3 and SMMC-7721 and nude mice subcutaneously tumor model to study whether Sal could increase the sensitivity of hepatoma cells to the traditional chemotherapeutic agent such as 5-FU. The combination of Sal and 5-FU resulted in a synergistic antitumor effect against liver tumors both in vitro and in vivo. Sal reversed the 5-FU-induced increase in CD133(+) EPCAM(+) cells, epithelial–mesenchymal transition and activation of the Wnt/β-catenin signaling pathway. The combination of Sal and 5-FU may provide us with a new approach to reverse drug resistant for the treatment of patients with HCC.

CD133 facilitates epithelial-mesenchymal transition through interaction with the ERK pathway in pancreatic cancer metastasis

BACKGROUND

Pancreatic cancer is a lethal disease due to the high incidence of metastasis at the time of detection. CD133 expression in clinical pancreatic cancer correlates with poor prognosis and metastasis. However, the molecular mechanism of CD133-regulated metastasis remains unclear. In recent years, epithelial-mesenchymal transition (EMT) has been linked to cancer invasion and metastasis. In the present study we investigated the role of CD133 in pancreatic cancer metastasis and its potential regulatory network.

METHODS

A highly migratory pancreatic cancer cell line, Capan1M9, was established previously. After shRNA was stable transducted to knock down CD133 in Capan1M9 cells, gene expression was profiled by DNA microarray. Orthotopic, splenic and intravenous transplantation mouse models were set up to examine the tumorigenesis and metastatic capabilities of these cells. In further experiments, real-time RT-PCR, Western blot and co-immunoprecipitate were conducted to evaluate the interactions of CD133, Slug, N-cadherin, ERK1/2 and SRC.

RESULTS

We found that CD133+ human pancreatic cancer cells were prone to generating metastatic nodules in in vivo models using immunodeficient mice. In contrast, CD133 knockdown suppressed cancer invasion and metastasis in vivo. Gene profiling analysis suggested that CD133 modulated mesenchymal characteristics including the expression of EMT-related genes, such as Slug and N-cadherin. These genes were down-regulated following CD133 knockdown. Moreover, CD133 expression could be modulated by the extracellular signal-regulated kinase (ERK)1/2 and SRC signaling pathways. The binding of CD133 to ERK1/2 and SRC acts as an indispensable mediator of N-cadherin expression.

CONCLUSIONS

These results demonstrate that CD133 plays a critical role in facilitating the EMT regulatory loop, specifically by upregulating N-cadherin expression, leading to the invasion and metastasis of pancreatic cancer cells. Our study provides a novel insight into the function of CD133 in the EMT program and a better understanding of the mechanism underlying the involvement of CD133 in pancreatic cancer metastasis.

STAT3 in hepatocellular carcinoma: new perspectives

Chronic liver damage and inflammation are strong promoters of hepatocellular carcinoma (HCC) formation. HCC cells communicate with inflammatory and stromal cells via cytokine/chemokine signals. These heterotypic interactions inhibit immunologic anticancer activities and promote protumorigenic activities, such as angiogenesis or invasiveness. STAT3 mediates several reciprocal interactions between liver cancer cells and stromal cells and modulates preconditions of tumor formation such as chronic inflammation. Therefore, activation of STAT3 is considered as a tumor-promoting event in HCC formation. However, the oncogenic role of STAT3 in cancers has been challenged by several reports that suggest a tumor-suppressive activity. Here we discuss tumor-promoting and tumor-suppressive effects of cytokine-activated STAT3 in HCC.

8-bromo-5-hydroxy-7-methoxychrysin targeting for inhibition of the properties of liver cancer stem cells by modulation of Twist signaling

Emerging evidence has suggested that cancer stem cells with expression of surface biomarkers including CD133 and CD44 have more aggressive biological behavior, including epithelial-mesenchymal transition (EMT), which are closely related to invasion. The upregulation and nuclear relocation of the EMT regulator Twist1 have been implicated in the tumor invasion and metastasis of human hepatocellular carcinoma (HCC). In this study, we aimed to isolate and characterize a small population of CD133+ cells that existed in the HCC cell line SMMC-7721 by MACS and investigated the possible roles of 8-bromo-7-methoxychrysin (BrMC), a synthetic analogue of chrysin, in inhibiting the properties of CD133+ sphere-forming cells (SFCs) derived from the HCC cell line SMMC-7721, namely liver cancer stem cells (LCSCs). Based on the data, BrMC inhibited the proliferation, self-renewal and invasion of LCSCs in vitro and in vivo, downregulated the expression of the LCSC biomarkers CD133 and CD44 and induced EMT by downregulating the expression of Twist and β-catenin in LCSCs. BrMC potentiated the inhibition of LCSCs self-renewal after reduction of twist protein levels, which was attenuated when twist was overexpressed. This study not only provides an important experimental and theoretical basis for investigation of BrMC in LCSCs, but also helps in the development of effective therapeutic medicine for HCC.

The pan-deacetylase inhibitor panobinostat modulates the expression of epithelial-mesenchymal transition markers in hepatocellular carcinoma models

Deacetylase inhibitors (DACis) represent a novel therapeutic option for human cancers by classically affecting proliferation or apoptosis. Since transdifferentiation and dedifferentiation play a key role in carcinogenesis, we investigated the epigenetic influence on the molecular differentiation status in human hepatocellular carcinoma (HCC) models. Markers of differentiation, including cytokeratin (Ck) 7, Ck8, Ck18, Ck19, Ck20, vimentin, sonic hedgehog homolog (SHH), smoothened (Smo), patched (Ptc), glioma-associated oncogene homolog 1 (Gli1), CD133, octamer-binding transcription factor 4 (Oct4) and β-catenin, were examined in the human HCC cell lines HepG2 and Hep3B in vitro and in vivo (xenograft model) using quantitative real-time PCR and immunohistochemistry following treatment with the pan-DACi panobinostat (LBH589). Compared to untreated controls, treated HepG2 xenografts, and to a lesser extent cell lines, demonstrated a significant increase of differentiation markers Ck7 and Ck19 (classical cholangiocellular type) and Ck8 and Ck18 (classical HCC type), and a decreased level of dedifferentiation markers vimentin (mesenchymal) and SHH/Ptc (embryonic), paralleled with a more membranous expression of β-catenin. These findings were dose-dependently correlated with tumor size, necrosis rate, microvessel density and mitosis/Ki-67-associated proliferation rate. Our results demonstrate that the differentiation status of human HCC cells is influenced by the pan-DACi panobinostat, indicating that this treatment may influence the epithelial-mesenchymal transition (EMT) status related to metastasis and aggressiveness.

Hepatitis C virus induces epithelial-mesenchymal transition in primary human hepatocytes

Hepatitis C virus (HCV)-mediated liver disease progression may reflect distinct molecular mechanisms for increased hepatocyte growth and hepatic stellate cell activation. In this study, we have observed that primary human hepatocytes, when infected in vitro with cell culture-grown HCV genotype 1a or 2a, display viral RNA and protein expression. Infected hepatocytes displayed a fibroblast-like shape and an extended life span. To understand the changes at the molecular level, we examined epithelial-mesenchymal transition (EMT) markers. Increased mRNA and protein expression levels of vimentin, snail, slug, and twist and a loss of the epithelial cell marker E-cadherin were observed. Snail and twist, when examined separately, were upregulated in chronically HCV-infected liver biopsy specimens, indicating an onset of an active EMT state in the infected liver. An increased expression level of fibroblast-specific protein 1 (FSP-1) in the infected hepatocytes was also evident, indicating a type 2 EMT state. Infected hepatocytes had significantly increased levels of phosphorylated β-catenin (Ser(552)) as an EMT mediator, which translocated into the nucleus and activated Akt. The phosphorylation level of β-catenin at Thr(41)/Ser(45) moieties was specifically higher in control than in HCV-infected hepatocytes, implicating an inactivation of β-catenin. Together, these results suggested that primary human hepatocytes infected with cell culture-grown HCV display EMT via the activation of the Akt/β-catenin signaling pathway. This observation may have implications for liver disease progression and therapeutic intervention strategies using inhibitory molecules.

Antisense oligonucleotide against clusterin regulates human hepatocellular carcinoma invasion through transcriptional regulation of matrix metalloproteinase-2 and E-cadherin

Secreted clusterin (sCLU) has been shown to be overexpressed in metastatic hepatocellular carcinoma (HCC) tissue, and its overexpression in HCC cells increases cell migration and the formation of liver metastatic tumor nodules in vivo. In this study, we tested the hypothesis that sCLU plays a role in the invasiveness of human HCC and may be associated with its metastatic spread. HCCLM3, a human hepatocellular carcinoma cell line, was transiently transfected with an antisense oligonucleotide (ASO) against sCLU (OGX-011). HepG2 liver hepatocellular cells were transiently transfected with the pc.DNA3.1-sCLU plasmid to overexpress sCLU, and subsequently evaluated for effects on invasion and the expression of molecules involved in invasion. We observed that suppression of the sCLU gene significantly reduced the invasive capability of the highly invasive HCCLM3 cells, and vice versa in the low invasive HepG2 cell line. The results revealed that knockdown of sCLU by OGX-011 resulted in a significant increase in the expression of E-cadherin and a decrease in matrix metalloproteinase-2 (MMP-2) gene transcription. Overexpression of sCLU by transfection with pc.DNA3.1-sCLU significantly decreased the expression of E-cadherin and increased MMP-2 gene transcription. These data were further verified by reverse transcription-PCR and Western blot analysis. A significant reduction in MMP-2 expression and an increase in E-cadherin expression in sCLU-knockdown HCCLM3 cells were observed, as well as a significant increase in MMP-2 expression and a decrease in E-cadherin expression in HepG2 cells overexpressing sCLU. These data indicate a role for sCLU in augmenting MMP-2 transcription and decreasing E-cadherin expression. Our data show the involvement of sCLU in human HCC invasion, and demonstrate that silencing sCLU gene expression inhibits the invasion of human HCC cells by inhibiting MMP-2 expression and promoting E-cadherin expression. Thus, OGX-011 could be an effective therapeutic agent for HCC.

CD133(+)CXCR4(+) colon cancer cells exhibit metastatic potential and predict poor prognosis of patients

BACKGROUND

Colorectal cancer (CRC), which frequently metastasizes to the liver, is one of the three leading causes of cancer-related deaths worldwide. Growing evidence suggests that a subset of cells exists among cancer stem cells. This distinct subpopulation is thought to contribute to liver metastasis; however, it has not been fully explored in CRC yet.

METHODS

Flow cytometry analysis was performed to detect distinct subsets with CD133 and CXCR4 markers in human primary and metastatic CRC tissues. The 'stemness' and metastatic capacities of different subpopulations derived from the colon cancer cell line HCT116 were compared in vitro and in vivo. The roles of epithelial-mesenchymal transition (EMT) and stromal-cell derived factor-1 (SDF-1) in the metastatic process were also investigated. A survival curve was used to explore the correlation between the content of CD133(+)CXCR4(+) cancer cells and patient survival.

RESULTS

In human specimens, the content of CD133(+)CXCR4(+) cells was higher in liver metastases than in primary colorectal tumors. Clonogenic and tumorigenic cells were restricted to CD133(+) cells in the HCT116 cell line, with CXCR4 expression having no impact on the 'stemness' properties. We found that CD133(+)CXCR4(+)cancer cells had a high metastatic capacity in vitro and in vivo. Compared with CD133(+)CXCR4(-) cells, CD133(+)CXCR4(+)cancer cells experienced EMT, which contributed partly to their metastatic phenotype. We then determined that SDF-1/CXCL12 treatment could further induce EMT in CD133(+)CXCR4(+)cancer cells and enhance their invasive behavior, while this could not be observed in CD133(+)CXCR4- cancer cells. Blocking SDF-1/CXCR4 interaction with a CXCR4 antagonist, AMD3100 (1,10-[1,4-phenylenebis(methylene)]bis-1,4,8,11 -tetraazacyclotetradecane octahydrochloride), inhibited metastatic tumor growth in a mouse hepatic metastasis model. Finally, a high percentage of CD133(+)CXCR4(+)cells in human primary CRC was associated with a reduced two-year survival rate.

CONCLUSIONS

Strategies targeting the SDF-1/CXCR4 interaction may have important clinical applications in the suppression of colon cancer metastasis. Further investigations on how high expression of CXCR4 and EMT occur in this identified cancer stem cell subset are warranted to provide insights into our understanding of tumor biology.

miR-548c-5p inhibits proliferation and migration and promotes apoptosis in CD90(+) HepG2 cells

BACKGROUND

Since the introduction of the theory of tumour stem cells (TSCs), the liver cancer stem cell (LCSC)-like cells have become one of the focuses in the research on liver cancer. MATERIALS AND METHODS.: In this study, CD90(+) cells were applied as the possible LCSC-like cells, and the miRNA and gene expression were analyzed in the CD90(+) HepG2 cells. The pilot study showed miR-548c-5p exerted potential effect on the CD90(+) HepG2 cells and was thereafter applied for the further study. CD90(+) HepG2 cells were assigned to miR-548c-5p mimic transfection group and control group. MTT assay was performed to detect the proliferation of CD90(+) HepG2 cells. The migration and invasion abilities were examined by wound healing assay and transwell migration assay, respectively. A detection of apoptosis was performed by fluorescence microscopy.

RESULTS

Our results showed that caspase-3 and bcl-2 were down-regulated while caspase-8 was up-regulated in the CD90(+) HepG2 cells. Moreover, the miR-548c-5p transfection could down-regulate the expression of β-catenin, Tg737, bcl-2, bcl-XL, and caspase-3, inhibit the proliferation, migration and invasion and promote the apoptosis of the CD90(+) HepG2 cells.

CONCLUSIONS

Our findings indicate the imbalance between apoptosis and anti-apoptosis in the LCSC-like cells, which influence the biological features of LCSC-like cells. miRNA plays a regulatory role in the LCSC-like cells among which miR-548c-5p might be a suppressor.

Human hepatocellular carcinomas with "Stemness"-related marker expression: keratin 19 expression and a poor prognosis

There is a recently proposed subtype of hepatocellular carcinoma (HCC) that is histologically similar to usual HCC, but characterized by the expression of "stemness"-related markers. A large-scale study on two different cohorts of HCCs was performed to investigate the clinicopathologic features and epithelial-mesenchymal transition (EMT)-related protein expression status of this subtype of HCCs. The expression status of stemness-related (e.g., keratin 19 [K19], cluster of differentiation [CD]133, epithelial cell adhesion molecule [EpCAM], and c-kit) and EMT-related markers (e.g., snail, S100A4, urokinase plasminogen activator receptor [uPAR], ezrin, vimentin, E-cadherin, and matrix metalloproteinase [MMP]2) were examined using tissue microarrays from cohort 1 HCCs (n = 137). K19 protein expression in cohort 2 HCCs (n = 237) was correlated with the clinicopathologic parameters and messenger RNA (mRNA) levels of K19, uPAR, VIL2, Snail, Slug, and Twist. K19, EpCAM, c-kit, and CD133 positivity were observed in 18.2%, 35.0%, 34.3%, and 24.8%, respectively. K19 was most frequently expressed in combination with at least one other stemness-related marker (92.0%). K19-positive HCCs demonstrated more frequent major vessel invasion and increased tumor size, compared to K19-negative HCCs (P < 0.05). K19 was most significantly associated with EMT-related protein expression (e.g., vimentin, S100A4, uPAR, and ezrin) (P < 0.05) and a poor prognosis (overall survival: P = 0.018; disease-free survival: P = 0.007) in cohort 1. In cohort 2, HCCs with high K19 mRNA levels demonstrated higher mRNA levels of Snail, uPAR, and MMP2 (P < 0.05). K19-positive HCCs demonstrated more frequent microvascular invasion, fibrous stroma, and less tumor-capsule formation, compared to K19-negative HCCs (P < 0.05). K19 expression was a significant independent predictive factor of poor disease-free survival (P = 0.032).

CONCLUSION

K19 was well correlated with clinicopathologic features of tumor aggressiveness, compared to other stemness-related proteins. K19-positive HCCs showed significantly increased EMT-related protein and mRNA expression, suggesting that they may acquire more invasive characteristics, compared to K19-negative HCCs through the up-regulation of EMT-associated genes.

Contribution of cancer stem cells to tumor vasculogenic mimicry

Vasculogenic mimicry (VM), a newly-defined pattern of tumor blood supply, provides a special passage without endothelial cells and is conspicuously different from angiogenesis and vasculogenesis. The biological features of the tumor cells that form VM remain unknown. Cancer stem cells (CSCs) are believed to be tumor-initiating cells, capable of self-renewal and multipotent differentiation, which resemble normal stem cells in phenotype and function. Recently CSCs have been shown to contribute to VM formation as well as angiogenesis. These findings challenge the previous understanding of the cellular basis of VM formation. In this review, we present evidence for participation of CSCs in VM formation. We also discuss the potential mechanisms and possible interaction of CSCs with various elements in tumor microenvironment niche. Based on the importance of VM in tumor progression, it constitutes a novel therapeutic target for cancer.