Metastatic human hepatocellular carcinoma models in nude mice and cell line with metastatic potential

Bibliometric study of the application of the chicken embryo chorioallantoic membrane model in cancer research: the top 100 most cited articles

The chicken embryo chorioallantoic membrane (CAM) model has played a crucial role in various aspects of cancer research. The purpose of this study is to help researchers clarify the research direction and prospects of the CAM model. A bibliometric analysis was conducted on the top 100 most cited articles on use of the CAM model in tumour research, retrieved from the Web of Science Core Collection database. Tools such as Bibliometrix, VOSviewer, CiteSpace and Excel were utilized for the visualization network analysis. The 100 articles analysed were mainly from the USA, China and European countries such as Germany and France. Tumour research involving CAM model experiments demonstrated reliability and scientific rigor (average citation count = 156.2). The analysis of keywords, topics and subject areas revealed that the applications of this model ranged from the biological characteristics of tumours to molecular mechanisms and signaling pathways, to recent developments in nanotechnology and clinical applications. Additionally, nude mouse experiments have been more frequently performed in recent years. We conclude that the CAM model is efficient, simple and cost-effective, and has irreplaceable value in various aspects of cancer research. In the future, the CAM model can further contribute to nanotechnology research.

Mouse Models of Hepatocellular Carcinoma: Classification, Advancement, and Application

Hepatocellular carcinoma (HCC) is the subtype of liver cancer with the highest incidence, which is a heterogeneous malignancy with increasing incidence rate and high mortality. For ethical reasons, it is essential to validate medical clinical trials for HCC in animal models before further consideration on humans. Therefore, appropriate models for the study of the pathogenesis of the disease and related treatment methods are necessary. For tumor research, mouse models are the most commonly used and effective in vivo model, which is closer to the real-life environment, and the repeated experiments performed on it are closer to the real situation. Several mouse models of HCC have been developed with different mouse strains, cell lines, tumor sites, and tumor formation methods. In this review, we mainly introduce some mouse HCC models, including induced model, gene-edited model, HCC transplantation model, and other mouse HCC models, and discuss how to choose the appropriate model according to the purpose of the experiments.

Killing efficiency affected by mutually modulated PD-1 and PD-L1 expression via NKT-hepatoma cell interactions

Aim: To explore the expression of programmed death-1 (PD-1) or programmed death ligand 1 (PD-L1), natural killer T (NKT) and hepatoma cells in coculture system, and the influence of abolishing PD-1 on antitumor efficiency. Materials & methods: CRISPR/Cas9 technology, flow cytometry, ELISA, CCK-8 assay and mouse models were performed to investigate the interactions between PD-1/PD-L1 expression on NKT and hepatoma cells, respectively. Results: The NKT and hepatoma cells mutually affected the expression of PD-1/PD-L1. The killing effect was positively correlated with NKT-mediated PD-L1 expression on hepatoma cells. Conclusion: Hepatoma cells in different genetic background responded differently to NKT-induced PD-L1 stimulation, and those cells with lower PD-L1 expression fail to PD-1 blocking intervention. Additionally, the killing effect was more time-efficient with PD-1 knockout than with monoclonal antibody blockade.

Study on the hepatocellular carcinoma model with metastasis

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related death around the world due to advanced clinical stage at diagnosis, high incidence of recurrence and metastasis after surgical treatment. It is in urgent need to create appropriate animal models to explore the mechanism, patterns, risk factors, and therapeutic strategies of HCC metastasis and recurrence. However, most of the established models lack the phenotype of invasion and metastasis in patient, or have unstable phenotype. To establish HCC models with stable metastasis phenotype requires profound understanding in cancer metastasis biology and scientific methodology. Over the past 3 decades, HCC models with stable metastasis have been extensively studied. This paper reviewed the history and development of HCC animal models and cell models, focusing on the screening and maintaining of metastatic potential and phenotype. In-depth studies using these models vastly promote the understanding of cellular and molecular mechanisms and development of therapeutic strategies on HCC metastasis.

Targeting SphK2 Reverses Acquired Resistance of Regorafenib in Hepatocellular Carcinoma

Background: Regorafenib is a second-line therapy drug used for advanced hepatocellular carcinoma (HCC). Unfortunately, the survival benefit of the patients receiving this treatment is modest, which may be attributed to drug resistance. In the present study, sphingosine kinase 2 (SphK2) was targeted to reverse regorafenib resistance in HCC.

Methods: The functions of SphK2 and sphingosine-1-phosphate (S1P), the catalytic product of SphK2 in regorafenib resistance of HCC cells, were evaluated by cell counting kit-8 assay, colony formation, cell cycle evaluation, and annexin V–fluorescein isothiocyanate/propidium iodide double-staining assay. The antitumor activity of combined treatment of regorafenib and the SphK2-specific inhibitor ABC294640 was examined in HCC cells in vitro and xenograft model in vivo. The molecular mechanisms of SphK2/S1P-mediating regorafenib resistance were investigated using cell line establishment and Western blot analysis.

Results: Well-developed regorafenib-resistant HCC cells indicated high expression levels of SphK2. The sensitivity to regorafenib of regorafenib-resistant HCC cells was restored following SphK2 knockdown or pharmacological inhibition by ABC294640. In addition, ectopic expression of SphK2 and exogenous addition of S1P decreased the sensitivity of HCC cells to regorafenib. Furthermore, the combination treatment with ABC294640 sensitized resistant tumor to regorafenib in xenograft model of HCC. The phosphorylation levels of nuclear factor κB (NF-κB), as well as those of signal transducer and activator of transcription 3 (STAT3), were positively associated with SphK2 and S1P.

Conclusions: SphK2/S1P mediates regorafenib resistance of HCC through NF-κB and STAT3 activation. Targeting SphK2 by ABC294640 potently reduces regorafenib resistance of HCC cells both in vitro and in vivo. The combination of ABC294640 and regorafenib could be developed as a novel potential treatment strategy for advanced HCC.

Whole-exome mutational landscape of metastasis in patient-derived hepatocellular carcinoma cells

In order to explore the genomic basis for liver cancer metastasis, whole-exome sequencing (WES) was performed on patient-derived hepatocellular carcinoma (HCC) cell lines with differential metastatic potentials and analyzed their clonal evolution relationships. An evolutionary tree based on genomic single nucleotide polymorphism (SNP) was constructed in MegaX software. The WES data showed that the average percentage of heterogeneous mutations in each HCC cell lines was 16.55% (range, 15.38%–18.17%). C: G > T: A and T: A > C: G somatic transitions were the two most frequent substitutions. In these metastatic HCC cell lines, non-silent gene mutations were found in 21.88% of known driver genes and 10 classical signaling pathways. The protein interaction network was constructed by STRING, and hub genes were found in the shared trunk mutation genes and the heterogeneous branch mutations respectively. In cBioPortal database, some of the selected hub genes were found to be associated with poor overall survival (OS) of HCC patients. Among the mutated HCC driver genes, a novel KEAP1 mutation with a homozygous frameshift truncation at the c-terminal Nrf2 binding region was detected and verified in MHCC97-H and HCC97LM3 cells. In conclusion, WES data demonstrate that HCC cell lines from tumor biopsy specimens of the same patient have obtained different metastatic potentials through repeated selection in rodents in vivo, and they do indeed have a genetic relationship at the genomic level.

MiR-612 regulates invadopodia of hepatocellular carcinoma by HADHA-mediated lipid reprogramming

Background

MicroRNA-612 (miR-612) has been proven to suppress EMT, stemness, and tumor metastasis of hepatocellular carcinoma (HCC) via PI3K/AKT2 and Sp1/Nanog signaling. However, its biological roles on HCC progression are far from elucidated.

Methods

We found direct downstream target of miR-612, hadha by RNA immunoprecipitation and sequencing. To explore its biological characteristic, potential molecular mechanism, and clinical relevance in HCC patients, we performed several in-vitro and in-vivo models, as well as human tissue chip.

Results

Ectopic expression of miR-612 could partially reverse the level of HADHA, then suppress function of pseudopods, and diminish metastatic and invasive potential of HCC by lipid reprogramming. In detail, miR-612 might reduce invadopodia formation via HADHA-mediated cell membrane cholesterol alteration and accompanied with the inhibition of Wnt/β-catenin regulated EMT occurrence. Our results showed that the maximum oxygen consumption rates (OCR) of HCCLM3^miR-612-OE and HCCLM3^hadha-KD cells were decreased nearly by 40% and 60% of their counterparts (p < 0.05). The levels of acetyl CoA were significantly decreased, about 1/3 (p > 0.05) or 1/2 (p < 0.05) of their controls, in exogenous miR-612 or hadha-shRNA transfected HCCLM3 cell lines. Besides, overexpression of hadha cell lines had a high expression level of total cholesterol, especially 27-hydroxycholesterol (p < 0.005). SREBP2 protein expression level as well as its downstream targets, HMGCS1, HMGCR, MVD, SQLE were all deregulated by HADHA. Meanwhile, the ATP levels were reduced to 1/2 and 1/4 in HCCLM3^miR-612-OE (p < 0.05) and HCCLM3^hadha-KD (p < 0.01) respectively. Moreover, patients with low miR-612 levels and high HADHA levels had a poor prognosis with shorter overall survival.

Conclusion

miR-612 can suppress the formation of invadopodia, EMT, and HCC metastasis and by HADHA-mediated lipid programming, which may provide a new insight of miR-612 on tumor metastasis and progression.

In-depth analysis of secretome and N-glycosecretome of human hepatocellular carcinoma metastatic cell lines shed light on metastasis correlated proteins

Cancer cell metastasis is a major cause of cancer fatality. But the underlying molecular mechanisms remain incompletely understood, which results in the lack of efficient diagnosis, therapy and prevention approaches. Here, we report a systematic study on the secretory proteins (secretome) and secretory N-glycoproteins (N-glycosecretome) of four human hepatocellular carcinoma (HCC) cell lines with different metastatic potential, to explore the molecular mechanism of metastasis and supply the clues for effective measurement of diagnosis and therapy. Totally, 6242 unique gene products (GPs) and 1637 unique N-glycosites from 635 GPs were confidently identified. About 4000 GPs on average were quantified in each of the cell lines, 1156 of which show differential expression (p<0.05). Ninety-nine percentage of the significantly altered proteins were secretory proteins and proteins correlated to cell movement were significantly activated with the increasing of metastatic potential of the cell lines. Twenty-three GPs increased both in the secretome and the N-glycosecretome were chosen as candidates and verified by western blot analysis, and 10 of them were chosen for immunohistochemistry (IHC) analysis. The cumulative survival rates of the patients with candidate (FAT1, DKK3) suggested that these proteins might be used as biomarkers for HCC diagnosis. In addition, a comparative analysis with the published core human plasma database (1754 GPs) revealed that there were 182 proteins not presented in the human plasma database but identified by our studies, some of which were selected and verified successfully by western blotting in human plasma.

Animal models as a tool in hepatocellular carcinoma research: A Review

Cancer is the first cause of death in developed countries and the second in developing countries. Concerning the most frequent worldwide-diagnosed cancer, primary liver cancer represents approximately 4% of all new cancer cases diagnosed globally. However, among primary liver cancer, hepatocellular carcinoma is by far the most common histological subtype. Notwithstanding the health promotion and disease prevention campaigns, more than half a million new hepatocellular carcinoma cases are reported yearly, being estimated to growth continuously until 2020. Taking this scenario under consideration and the fact that some aspects concerning hepatocellular carcinoma evolution and metastasize process are still unknown, animal models assume a crucial role to understand this disease. The animal models have also provided the opportunity to screen new therapeutic strategies. The present review was supported on research and review papers aiming the complexity and often neglected chemically induced animal models in hepatocarcinogenesis research. Despite the ongoing debate, chemically induced animal models, namely, mice and rat, can provide unique valuable information on the biotransformation mechanisms against xenobiotics and apprehend the deleterious effects on DNA and cell proteins leading to carcinogenic development. In addition, taking under consideration that no model achieves all hepatocellular carcinoma research purposes, criteria to define the " ideal" animal model, depending on the researchers' approach, are also discussed in this review.

Characteristics and experimental applications of human hepatocellular carcinoma cell lines

At present, primary hepatocellular carcinoma (HCC), a malignant tumor with a high incidence rate in China, is associated with a high mortality rate as well as a treatment dilemma. The research on HCC is always a hot topic. However, due to ethical considerations, research on HCC cannot directly be done in humans. The establishment of human HCC cell line model has overcome this obstacle. Derived from the tissue of human HCC, HCC cell lines have a complete set of human genes and relatively stable passages. This paper introduces the origins and characteristics of cell lines commonly used in experiments, such as SMMC7721, Bel-7402, MHCC97, HepG2, Hep3B, Huh-7, and PLC/PRF/5, as well as their roles and applications in HCC research.

miR-612 suppresses stem cell-like property of hepatocellular carcinoma cells by modulating Sp1/Nanog signaling

In our previous study we found that miR-612 negatively regulated stem cell-like property and tumor metastasis of hepatocellular carcinoma cells (HCC). In this study, we try to elucidate underlying mechanism of the regulation, and find that miR-612 inversely modulate the mRNA and protein level of epithelial cell adhesion molecule as well as CD133, negatively regulate the numbers and sizes of tumor spheres, directly inhibit the protein level of Sp1, and subsequently reduce transcription activity of Nanog. Of importance, the higher levels of Sp1 and Nanog in biopsies are the more unfavorable prognoses of HCC patients are found after tumor resection. Taken together, miR-612 has a suppressive role on HCC stemness via Sp1/Nanog signaling pathway.

Malic enzyme 1 induces epithelial-mesenchymal transition and indicates poor prognosis in hepatocellular carcinoma

Malic enzyme 1 (ME1) links the glycolytic and citric acid cycles and is important for NADPH production, glutamine metabolism, and lipogenesis. Recently, its deregulation has been implicated in the progression of various cancers. However, the role of ME1 in the progression of hepatocellular carcinoma (HCC) remains unclear. In this study, we utilized short hairpin RNA-mediated gene silencing to investigate the biological effects of ME1 depletion in HCC and determined its prognostic significance in HCC. ME1 expression was examined by real-time (RT)-PCR and Western blot using five HCC cell lines and one normal liver cell line. We used polyethylenimine nanoparticles to deliver a short hairpin RNA to induce cessation of ME1 expression in HCC cells. Changes in NADPH production and reactive oxygen species (ROS) production were studied. Metastatic potentials of HCC cells were evaluated in vitro. Furthermore, we evaluated the protein level of ME1 in para-tumor and cancerous tissues of 65 HCC patients with detailed clinical, pathological, and clinical follow-up data. Patients' survivals were further assessed as well. Upregulated ME1 expression was observed in HCC cell lines. Downregulation of ME1 attenuated NADPH production and stimulated ROS production. Silencing ME1 was noted to inhibit migratory and invasive properties of HCC cells by inducing the E-cadherin expression and decreasing of N-cadherin and vimentin expression in a ROS-dependent pathway. Overexpression of ME1 was observed in a major fraction of HCC samples. Higher level of ME1 in tumors was significantly associated with reduced overall survival (Kaplan-Meier analysis, P = 0.024) and reduced progression-free survival (Kaplan-Meier analysis, P = 0.011). Inhibition of ME1 expression decreases HCC metastasis via suppression of epithelial-mesenchymal transition (EMT) processes in ROS-induced pathways. ME1 overexpression associates with unfavorable prognoses in patients with HCC, suggesting that ME1 is a poor prognostic predictor of hepatocellular carcinoma.

N-glycoproteome analysis of the secretome of human metastatic hepatocellular carcinoma cell lines combining hydrazide chemistry, HILIC enrichment and mass spectrometry

Cancer cell metastasis is a major cause of cancer death. Unfortunately, the underlying molecular mechanisms remain unknown, which results in the lack of efficient diagnosis, therapy and prevention approaches. Nevertheless, the dysregulation of the cancer cell secretome is known to play key roles in tumor transformation and progression. The majority of proteins in the secretome are secretory proteins and membrane-released proteins, and, mostly, the glycosylated proteins. Until recently, few studies have explored protein N-glycosylation changes in the secretome, although protein glycosylation has received increasing attention in the study of tumor development processes. Here, the N-glycoproteins in the secretome of two human hepatocellular carcinoma (HCC) cell lines with low (MHCC97L) or high (HCCLM3) metastatic potential were investigated with a in-depth characterization of the N-glycosites by combining two general glycopeptide enrichment approaches, hydrazide chemistry and zwitterionic hydrophilic interaction chromatography (zic-HILIC), with mass spectrometry analysis. A total of 1,213 unique N-glycosites from 611 N-glycoproteins were confidently identified. These N-glycoproteins were primarily localized to the extracellular space and plasma membrane, supporting the important role of N-glycosylation in the secretory pathway. Coupling label-free quantification with a hierarchical clustering strategy, we determined the differential regulation of several N-glycoproteins that are related to metastasis, among which AFP, DKK1, FN1, CD151 and TGFβ2 were up-regulated in HCCLM3 cells. The inclusion of the well-known metastasis-related proteins AFP and DKK1 in this list provides solid supports for our study. Further western blotting experiments detecting FN1 and FAT1 confirmed our discovery. The glycoproteome strategy in this study provides an effective means to explore potential cancer biomarkers.

The scent fingerprint of hepatocarcinoma: in-vitro metastasis prediction with volatile organic compounds (VOCs)

BACKGROUND

Hepatocellular carcinoma (HCC) is a common and aggressive form of cancer. Due to a high rate of postoperative recurrence, the prognosis for HCC is poor. Subclinical metastasis is the major cause of tumor recurrence and patient mortality. Currently, there is no reliable prognostic method of invasion.

AIM

To investigate the feasibility of fingerprints of volatile organic compounds (VOCs) for the in-vitro prediction of metastasis.

METHODS

Headspace gases were collected from 36 cell cultures (HCC with high and low metastatic potential and normal cells) and analyzed using nanomaterial-based sensors. Predictive models were built by employing discriminant factor analysis pattern recognition, and the classification success was determined using leave-one-out cross-validation. The chemical composition of each headspace sample was studied using gas chromatography coupled with mass spectrometry (GC-MS).

RESULTS

Excellent discrimination was achieved using the nanomaterial-based sensors between (i) all HCC and normal controls; (ii) low metastatic HCC and normal controls; (iii) high metastatic HCC and normal controls; and (iv) high and low HCC. Several HCC-related VOCs that could be associated with biochemical cellular processes were identified through GC-MS analysis.

CONCLUSION

The presented results constitute a proof-of-concept for the in-vitro prediction of the metastatic potential of HCC from VOC fingerprints using nanotechnology. Further studies on a larger number of more diverse cell cultures are needed to evaluate the robustness of the VOC patterns. These findings could benefit the development of a fast and potentially inexpensive laboratory test for subclinical HCC metastasis.

The microRNA miR-139 suppresses metastasis and progression of hepatocellular carcinoma by down-regulating Rho-kinase 2

BACKGROUND & AIMS

We investigated mechanisms of hepatocellular carcinoma (HCC) metastasis and identified an antimetastatic microRNA (miRNA), miR-139, that is down-regulated in human HCC samples.

METHODS

Effects of stable and transient expression of miRNA-139 and its inhibitors were studied in the human HCC cell lines SMMC-7721 and BEL7402; cells were analyzed for migration and invasion. Liver samples from patients with metastatic HCC were analyzed for levels of miRNA-139; data were compared with survival data using the Kaplan-Meier method and compared between groups by the log-rank test. Tumor formation and metastasis from human HCC MHCC97L cells that did or did not express miR-139 were analyzed in mice.

RESULTS

Down-regulation of miR-139 in HCC was associated significantly with poor prognosis of patients and features of metastatic tumors, including venous invasion, microsatellite formation, absence of tumor encapsulation, and reduced differentiation. miR-139 expression was reduced in metastatic HCC tumors compared with primary tumors. Overexpression of miR-139 in HCC cells significantly reduced cell migration and invasion in vitro and the incidence and severity of lung metastasis from orthotopic liver tumors in mice. miR-139 interacted with the 3' untranslated region of Rho-kinase 2 (ROCK2) and reduced its expression in HCC cells. Levels of miR-139 were correlated inversely with ROCK2 protein in human HCC samples. Overexpression of miR-139 did not inhibit HCC cell motility when ROCK2 was knocked down.

CONCLUSIONS

The microRNA miR-139 interacts with ROCK2 and reduces its expression in HCC cells. Down-regulation of miR-139 increased the invasive abilities of HCC cells in vitro and HCC metastasis in vivo. Expression of miR-139 is reduced in human metastatic HCC samples and correlates with prognosis.

Impact of metronomic UFT/cyclophosphamide chemotherapy and antiangiogenic drug assessed in a new preclinical model of locally advanced orthotopic hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an intrinsically chemotherapy refractory malignancy. Development of effective therapeutic regimens would be facilitated by improved preclinical HCC models. Currently, most models consist of subcutaneous human tumor transplants in immunodeficient mice; however, these do not reproduce the extensive liver disease associated with HCC or metastasize. To address this deficiency, we developed an orthotopic model. Human HCC cells were transfected with the gene encoding secretable beta-subunit human choriogonadotropin (beta-hCG), which was used as a surrogate marker of tumor burden. The HCC cells were implanted into the left liver lobe of severe combined immunodeficient (SCID) mice, after which the efficacy of different therapies was evaluated on established, but liver-confined human Hep3B cell line HCC. Treatments included sorafenib or metronomic chemotherapy using cyclophosphamide (CTX), UFT, an oral 5-fluorouracil prodrug, or doxorubicin either alone or in various combinations, with or without an antiangiogenic agent, DC101, an anti-vascular endothelial growth factor receptor-2 antibody. Sorafenib inhibited tumor growth in a dose-dependent manner but caused severe weight loss in SCID mice, thus necessitating use of DC101 in subsequent experiments. Although less toxicity was observed using either single or doublet metronomic chemotherapy without any added antiangiogenic agent, none, provided survival benefit. In contrast, significantly improved overall survival was observed using various combinations of metronomic chemotherapy regimens such as UFT + CTX with DC101. In conclusion, using this model of liver-confined but advanced HCC suggests that the efficacy of a targeted antiangiogenic drug or metronomic chemotherapy can be mutually enhanced by concurrent combination treatment.

Mouse models in liver cancer research: A review of current literature

Primary liver cancer remains one of the most lethal malignancies worldwide. Due to differences in prevalence of etiological factors the incidence of primary liver cancer varies among the world, with a peak in East-Asia. As this disease is still lethal in most of the cases, research has to be done to improve our understanding of the disease, offering insights for possible treatment options. For this purpose, animal models are widely used, especially mouse models. In this review, we describe the different types of mouse models used in liver cancer research, with emphasis on genetically engineered mice used in this field. We focus on hepatocellular carcinoma (HCC), as this is by far the most common type of primary liver cancer, accounting for 70%-85% of cases.

The effect of targeted magnetic nanopaticles on hepatoma and the expression of bcl-2/bax protein

The effect of targeted magnetic nanoparticles on hepatoma and the underlying mechanism were examined. Nude mice transplanted with a human hepatoma cell line (HepG2 cells) were randomized into 5 groups, including: (1) group A, receiving normal saline, (2) group B, receiving 5-fluorouracil (5-Fu), (3) group C, receiving magnetic nanoparticles containing 5-Fu, (4) group D, consisting of treatment with magnetic nanoparticles containing 5-Fu and inside magnetic field and (5) group E, receiving pure magnetic nanoparticles and inside magnetic field. Morphological features of transplanted tumors in mice in each group were observed under transmission electron microscope (TEM). The expression of bcl-2/bax protein was immunohistochemically detected by SABC method. The results showed that a large number of apoptotic tumor cells were found in group B and group D under TEM. The expression of bcl-2 protein was significantly decreased and the expression of bax protein increased significantly in both group B and D as compared with those in group A, C and E (P<0.01 for all). The decrease in bcl-2 and the increase in bax were more in group D as compared with group B (P<0.01). It is concluded that the targeted magnetic nanoparticles containing 5-Fu can improve the chemotherapeutic effect of 5-Fu by decreasing bcl-2 expression, increasing bax expression and inducing apoptosis of the liver cancer cells.

Generation and modulation of hepatocellular carcinoma circulating cells: a new experimental model

BACKGROUND

To establish a new experimental model of human hepatocellular carcinoma by orthotopic implantation of tumoral cells with its subsequent removal, to generate and modulate circulating tumoral cells.

MATERIALS AND METHODS

Three human hepatoma cell lines (HepG2, PLC/PRF, and Mahlavu) were orthotopically implanted under the Glisson's capsule of the left lateral lobe of the liver in a total of 56 non-obese diabetic/severe combined immunodeficiency mice. Tumor removal was performed 30 d after injection, and a laparotomy without tumor removal was done in control mice. Generation of circulating cells was monitored by flow cytometry using fluorescein isothiocyanate-conjugated anti-HLA antibody.

RESULTS

In 26 mice implanted with Mahlavu cells, 20 developed a unique tumor allowing a resection (77%), which was technically feasible in 80% of cases. The overall perioperative mortality was 30% (3/10) after resection; no mortality was observed in the control group. The circulating tumoral cells decreased dramatically after resection of the tumor as compared with control mice.

CONCLUSION

This new model is feasible and may be an interesting useful tool to study the hepatocellular carcinoma metastatic process and is consistent with the human clinical practice.

p19Arf inhibits the invasion of hepatocellular carcinoma cells by binding to C-terminal binding protein

The INK4A/ARF tumor suppressor locus is frequently inactivated in hepatocellular carcinoma (HCC), yet the consequences of this remain unknown. We recently described a HCC mouse model in which loss of the Ink4a/Arf locus accelerates the development of metastasis and enhances tumor cell migration and invasion in cell culture assays. We show here that knockdown of p19Arf in an HCC cell line increases invasion in cell culture assays. Furthermore, reintroduction of p19(Arf) into HCC cell lines lacking Ink4a/Arf inhibits tumor cell invasion, without affecting cell proliferation, or cell transformation as measured by soft agar colony formation. Inhibition of cell invasion by p19(Arf) was dependent on its C-terminal binding protein (CtBP) interaction domain but independent of Mdm2 binding and nucleolar localization. Indeed, RNA interference-mediated knockdown of CtBP1 or CtBP2 decreased cell invasion, and ectopic expression of CtBP2 enhanced tumor cell migration and invasion. Thus, our data indicate a novel role for the Arf tumor suppressor protein in regulating phenotypes associated with tumor progression and metastasis in HCC cells.

Effect of targeted magnetic nanoparticles containing 5-FU on expression of bcl-2, bax and caspase 3 in nude mice with transplanted human liver cancer

AIM: To investigate the anti-tumor effect and mechanisms of magnetic nanoparticles targeting hepatocellular carcinoma.

METHODS: Human hepatocellular carcinoma was induced in nude mice, and the mice were randomly divided into group A receiving normal saline, group B receiving magnetic nanoparticles containing 5-fluorouracil (5-FU), group C receiving 5-FU, and group D receiving magnetic nanoparticles containing 5-FU with a magnetic field built in tumor tissues. The tumor volume was measured on the day before treatment and 1, 4, 7, 10 and 13 d after treatment. Tumor tissues were isolated for examination of the expression of bcl-2, bax and caspase 3 by immunohistochemical method, reverse transcription polymerase chain reaction and Western blotting.

RESULTS: The tumor volume was markedly lower in groups C and D than in groups A and B (group C or D vs group A or B, P < 0.01). The volume was markedly lower in group D than in group C (P < 0.05). The expression of protein and mRNA of bcl-2 was markedly lower in groups C and D than in groups A and B (group C or D vs group A or B, P < 0.01), and was markedly lower in group D than in group C (P < 0.01). The expression of bax and caspase 3 in groups C and D was significantly increased, compared with that in groups A and B (P < 0.01).

CONCLUSION: The targeted magnetic nanoparticles containing 5-FU can improve the chemotherapeutic effect of 5-FU against hepatocellular carcinoma by decreasing the expression of bcl-2 gene, and increasing the expression of bax and caspase 3 genes.

Gene expression property of high-density three-dimensional tissue of HepG2 cells formed in radial-flow bioreactor

In our previous study, we examined three-dimensional culture using 5-ml radial-flow bioreactor (RFB) and showed that genes encoding cell cycle related proteins were suppressed in a stable phase. In this study, we analyzed the gene expression profiles of RFB-cultivated HepG2 cells and found that vascular endothelial growth factor (VEGF) production was strongly induced in the stable phase compared with the growth phase or static two-dimensional culture. When human umbilical vein endothelial cells (HUVECs) were grown under the conditioned medium of the stable phase, it was found that the formation of new blood vessels was induced in the angiogenesis model. DNA microarray analysis showed that the expression levels of both genes related to cell cycle arrest and which are known as tumor markers have increased in the stable phase. This result suggests that HepG2 cells in the stable phase maintain an active tumor phenotype. In addition, the expression of genes induced in the hypoxic condition was also induced in the stable phase. When the culture was carried out under a higher dissolved oxygen (DO) concentration, VEGF production did not decrease significantly and the new blood-vessel-forming ability of the conditioned medium was not suppressed. This suggests that the induction of VEGF production in a stable phase is not affected by DO during the tested level. These results suggest that the RFB cell culture system may be used to assess tumor progression mechanism under three-dimensional condition in vitro.

Inhibitory effects of docetaxel on expression of VEGF, bFGF and MMPs of LS174T cell

AIM: To study the effects of non-cytotoxic concentrations of docetaxel on some important angiogenic factors of LS174T Cells.

METHODS: The non-cytotoxic concentration of docetaxel and the activity of gelatinase were determined with MTT and gelatin zymography respectively, the expression of VEGF (vascular endothelial growth factor), bFGF (basic fibroblast growth factor), MMP (matrix metalloproteinase) 2 and MMP 9 was investigated with RT-PCR and Western blot.

RESULTS: The maximum non-cytotoxic concentration of docetaxel on LS174T Cells was 1.0 ng/mL. Compared with the solvent control group, 0.1, 0.5, 1.0 ng/mL of docetaxel could downregulate the expression of VEGF, bFGF, MMP 2 and MMP 9 and suppress the activity of gelatinase.

CONCLUSION: Our study suggests that the non-cytotoxic concentrations of docetaxel have strong antiangiogenic activity on LS174T Cells, which suggests docetaxel may be a promising antiangiogenic agent.

Expression of hsMAD2 in Human Hepatocellular carcinoma and its significance

AIM

To study the expression of hsMAD2 in primary human hepatocellular carcinoma(HCC) tissues and its significance.

METHODS

The expression of hsMAD2 was detected with immunohistochemical SABC method in 39 cases of HCC tissue and 26 cases of liver cirrhosis tissue and 3 cases of HCC cell lines, and the relationship between HCC pathological grade and hsMAD2 expression rate was analyzed.

RESULTS

Fifty nine percent (23/39) of HCC tissues expressed hsMAD2, the positive rate was 100% (15/15) in non-tumor liver cells adjacent to HCC and 92% (24/26) in cirrhosis tissues. No expression was found in 3 cases of HCC cell lines. There was no significant difference between pathological grade and expression rate of hsMAD2.However, there was a significant difference of expression of hsMAD2 between HCC tissues and cancerous tissues arrounding liver tissues (x²=6.888, P <0.01) and liver cirrhosis tissues(x²=8.656, P <0.01).

CONCLUSION

Expression rate of hsmad2 in HCC decreases significantly compared to surrounding liver tissues and liver cirrhosis tissues. hsMAD2 is possibly related to early pathogenesis of HCC.

Effects of KAI1 gene on KAI1 protein expression in MHCC97-H hepatocellular carcinoma cells with high metastatic potential

AIM

To construct sense and antisense KAI1 expression plasmids and to explore their effects on KAI1 protein expression in MHCC97-H hepatocellular carcinoma cells with high metastatic potential.

METHODS

Sense and antisense KAI1 expression plasmids were constructed using subclone technique and transfected into MHCC97-H cells by DOTAP liposome system. KAI1 protein expression in transfected MHCC97-H cells was analyzed with immunocytochemical SP method.

RESULTS

Analysis of restriction endonuclease indicated the structure of two recombinants was consistent with the expected results of sense and antisense KAI1 expression plasmids. Compared with MHCC97-H cells, KAI1 protein staining in the MHCC97-H-S cells transfected with sense KAI1 expression plasmid was obviously enhanced(Integra Oculus Dehter ,IOD 20.127±5.099 vs 12.675±1.921,P <0.05).However, KAI1 expression in the MHCC97-H-AS cells transfected with KAI1 antisense gene was obviously weakened (IOD 8.681±2.472 vs 12.675±1.921, P <0.05).

CONCLUSION

We successfully constructed sense and antisense KAI1 expression plasmids. Sense KAI1 gene can upregulate the expression of KAI1 protein in MHCC97-H cells. On the other hand, antisense KAI1 gene can downregulate the expression of KAI1 protein in MHCC97-H cells.

Gene expression profiles of hepatoma cell line HLE

AIM: To investigate the global gene expression of cancer related genes in hepatoma cell line HLE using Atlas Human Cancer Array membranes with 588 well-characterized human genes related with cancer and tumor biology.

METHODS: Hybridization of cDNA blotting membrane was performed with ³²P-labeled cDNA probes synthesized from RNA isolated from Human hepatoma cell line HLE and non-cirrhotic normal liver which was liver transplantation donor. AtlasImage, a software specific to array, was used to analyze the result. The expression pattern of some genes identified by Atlas arrays hybridization was confirmed by reverse transcription polymerase chain reaction (RT-PCR) in 24 pairs of specimens and Northern blot of 4 pairs of specimens.

RESULTS: The differential expression of cell cycle/growth regulator in hepatocellular carcinoma (HCC) showed a stronger tendency toward cell proliferation with more than 1.5-fold up-regulation of Cyclin C, ERK5, ERK6, E2F-3, TFDP-2 and CK4. The anti-apoptotic factors such as Akt-1 were up-regulated, whereas the promotive genes of apoptosis such as ABL2 were down-regulated. Among oncogene/tumors suppressors, SKY was down-regulated. Some genes such as Integrin beta 8, Integrin beta 7, DNA-PK, CSPCP, byglycan, Tenacin and DNA Topo were up-regulated. A number of genes, including LAR, MEK1, eps15, TDGF1, ARHGDIA were down-regulated. In general, expression of the cancer progression genes was up-regulated, while expression of anti-cancer progression genes was down-regulated. These differentially expressed genes tested with RT-PCR were in consistent with cDNA array findings.

CONCLUSION: Investigation of these genes in HCC is helpful in disclosing molecular mechanism of pathogenesis and progression of HCC. For the first time few genes were discovered in HCC. Further study is required for the precise relationship between the altered genes and their correlation with the pathogenesis of HCC.

The analysis of γ-glutamyl transpeptidase gene in different type liver tissues

AIM: To probe the value of γ-glutamyl transpeptidase (GGT) messenger RNA in monitoring canceration of liver cells and for early diagnosis of hepatocellular carcinoma (HCC), by researching the types of GGT messenger RNA (GGTmRNA) in liver tissues and peripheral blood of different hepatopathy.

METHODS: The three types of GGTmRNA (A, B, C) in liver tissues and peripheral blood from the patients with HCC, noncancerous hepatopathy, hepatic benign tumor, secondary carcinoma of liver, and healthy persons were detected by reverse-transcription polymerase chain reaction (RT-PCR).

RESULTS: (1) In normal liver tissues, type A was predominantly found (100.00%), type B was not found, type C was found occasionally (25.00%); (2) The distribution of types of GGTmRNA in liver tissues with acute hepatitis, chronic hepatitis, cirrhosis, alcoholic hepatopathy was similar as in normal liver tissues (P > 0.05), but type B was found in 3 of 18 patients with chronic hepatitis (16.67%), and also in 3 of 11 patients with cirrhosis (27.27%); (3) There was no significant difference of types of GGTmRNA between liver tissues with hepatic benign tumor, secondary carcinoma of liver and normal liver tissues (P > 0.05); (4) Type B was predominant in cancerous tissues with HCC (87.5%), the prevalence of type B in cancerous tissues was significantly higher than that in normal liver tissues (0/12) (P < 0.05), but the prevalence of type A in cancerous tissues (46.88%) was significantly lower than that in normal liver tissues (100.00%) (P < 0.05), and the prevalence of type C (6.25%) in cancerous was the same as that in normal liver tissues (25.00%) (P > 0.05). In noncancerous tissues of livers with HCC, the main types were type A and type B, the prevalence of type A (85.71%, 90.48%) and type C (14.29%, 9.52%) in noncancerous tissues of liver with HCC was similar as that in normal liver tissues (A: 100.00%; C: 25.00%) (P > 0.05), but the prevalence of type B (80.95%, 76.19%) in noncancerous tissues of livers with HCC was significantly higher than that in normal liver tissues (0/12) (P < 0.05); (5) The prevalence of type B (37.5%) in peripheral blood with HCC was higher than that in normal person (0/12) (P < 0.05). In peripheral blood, type B was found in 4 of 11 cases of HCC with serum AFP negative.

CONCLUSION: The shift of types of GGTmRNA from A to B in liver tissues may be closely related to the development of HCC, and the analysis of GGT gene may provide a useful tool for early diagnosis of HCC.

Gene cloning of murine alpha-fetoprotein gene and construction of its eukaryotic expression vector and expression in CHO cells

To clone the murine alpha-fetoprotein (AFP) gene, construct the eukaryotic expression vector of AFP and express in CHO cells, total RNA were extracted from Hepa 1-6 cells, and then the murine alpha-fetoprotein gene was amplified by RT-PCR and cloned into the eukaryotic expression vector pcDNA3.1. The recombinant of vector was identified by restriction enzyme analysis and sequencing. After transient transfection of CHO cells with the vector, Western blotting was used to detect the expression of AFP. It is concluded that the 1.8 kb murine alpha-fetoprotein gene was successfully cloned and its eukaryotic expression vector was successfully constructed.

Retrovirus-mediated gene transfer of human endostatin inhibits growth of human liver carcinoma cells SMMC7721 in nude mice

AIM: To study the effect of human endostatin mediated by retroviral gene transfer on the growth of human hepatocarcinoma cell line SMMC7721 in nude mice.

METHODS: Human endostatin gene together with rat serum albumin signal peptide was transferred into human liver carcinoma SMMC7721 cells by retroviral vector pLncx to build a stable transfectant (SMMC-endo). PCR and Western blot analysis were used to verify the transfection and secretion of human endostatin gene in SMMC7721 cells. The endothelial cell proliferation assay in vitro was conducted to test the biological activity of the expressed human endostatin. The inhibitory effect of endostatin expressed by transfected SMMC7721 on the growth rates of tumor cells in vivo was observed. The mean microvessel density in the specimen was also counted.

RESULTS: PCR amplification proved that the genome of SMMC-endo cells contained a 550 bp specific fragment of endostatin gene. Western blot analysis confirmed the secretion of human endostatin gene in the conditioned medium of transfected SMMC-endo cells. The endothelial proliferation assay showed that the conditioned medium of SMMC-endo cells significantly inhibited the proliferation of human umbilical vein endothelial cells by 48%, significantly higher than that of SMMC-pLncx (10.2%, P < 0.01). In vivo experiments revealed that only in 3 out of 5 mice tumors were formed and the mean size of flank tumors from SMMC-endo cells was 94.5% smaller than that from the control SMMC-pLncx cells 22 days after tumor inoculation (P < 0.001). The mean microvessel density in tumor samples from SMMC-endo cells was only 8.6 ± 1.1, much fewer than that of 22.6 ± 4.5 from SMMC-pLncx cells (P < 0.01).

CONCLUSION: Human endostatin mediated by retroviral gene transfer can inhibit human liver carcinoma cell SMMC7721 growth in nude mice.

An implantable rat liver tumor model for experimental transarterial chemoembolization therapy and its imaging features

AIM: To establish an ideal implantable rat liver tumor model for interventional therapy study and examine its angiographic signs and MRI, CT features before and after embolization.

METHODS: Forty male Wistar rats were implanted with Walker-256 tumor in the left lateral lobe of liver. Digital subtraction angiography (DSA) and transarterial chemoembolization were performed on day 14 after implantation. Native computer tomography (CT, n = 8) and native magnetic resonance (MR, n = 40) were performed between the day 8 and day 21 after implantation. The radiological morphological characteristics were correlated with histological findings.

RESULTS: Successful implantation was achieved in all forty rats, which was confirmed by CT and MRI. MR allowed tumor visualization from day 8 while CT from day 11 after implantation. The tumors were hypodensity on CT, hypointense on MR T1-weighted and hyperintense on T2-weighted. The model closely resembled human hepatocarcinoma in growth pattern and the lesions were rich in vasculature on angiography and got its filling mainly from the hepatic artery. Before therapy, tumor size was 211.9 ± 48.7 mm³. No ascites, satellite liver nodules or lung metastasis were found. One week after therapy, tumor size was 963.6 ± 214.8 mm³ in the control group and 356.5 ± 78.4 mm³ in TACE group. Ascites (4/40), satellite liver nodules (7/40) or lung metastasis (3/40) could be seen on day 21.

CONCLUSION: Walker-256 tumor rat model is suitable for the interventional experiment. CT and MRI are helpful in animal optioning and evaluating experimental results.

DNA-PKcs subunits in radiosensitization by hyperthermia on hepatocellular carcinoma hepG2 cell line

AIM: To investigate the role of DNA-PKcs subunits in radiosensitization by hyperthermia on hepatocellular carcinoma HepG₂ cell lines.

METHODS: HepG₂ cells were exposed to hyperthermia and irradiation. Hyperthermia was given at 45.5 °C. Cell survival was determined by an in vitro clonogenic assay for the cells treated with or without hyperthermia at various time points. DNA DSB rejoining was measured using asymmetric field inversion gel electrophoresis (AFIGE). The DNA-PKcs activities were measured using DNA-PKcs enzyme assay system.

RESULTS: Hyperthermia can significantly enhance irradiation-killing cells. Thermal enhancement ratio as calculated at 10% survival was 2.02. The difference in radiosensitivity between two treatment modes manifested as a difference in the α components and the almost same β components, which α value was considerably higher in the cells of combined radiation and hyperthermia as compared with irradiating cells (1.07 Gy^-1vs 0.44 Gy^-1). Survival fraction showed 1 logarithm increase after an 8-hour interval between heat and irradiation, whereas DNA-PKcs activity did not show any recovery. The cells were exposed to heat 5 min only, DNA-PKcs activity was inhibited at the nadir, even though the exposure time was lengthened. Whereas the ability of DNA DSB rejoining was inhibited with the increase of the length of hyperthermic time. The repair kinetics of DNA DSB rejoining after treatment with Wortmannin is different from the hyperthermic group due to the striking high slow rejoining component.

CONCLUSION: Determination with the cell extracts and the peptide phosphorylation assay, DNA-PKcs activity was inactivated by heat treatment at 45.5 °C, and could not restore. Cell survival is not associated with the DNA-PKcs inactivity after heat. DNA-PKcs is not a unique factor affecting the DNA DSB repair. This suggests that DNA-PKcs do not play a crucial role in the enhancement of cellular radiosensitivity by hyperthermia.

p53 immunohistochemical scoring: an independent prognostic marker for patients after hepatocellular carcinoma resection

AIM: To confirm if p53 mutation could be a routine predictive marker for the prognosis of hepatocellular carcinoma (HCC) patients.

METHODS: Two hundreds and forty-four formalin-fixed paraffin-embedded tumor samples of the patients with HCC receiving liver resection were detected for nuclear accumulation of p53. The percent of p53 immunoreactive tumor cells was scored as 0 to 3 + in p53 positive region (< 10% -, 10%-30% +, 31%-50% ++, > 50% +++). Proliferating cell nuclear antigen (PCNA) and some clinicopathological characteristics, including patients’ sex, preoperative serum AFP level, tumor size, capsule, vascular invasion (both visual and microscopic), and Edmondson grade were also evaluated.

RESULTS: In univariate COX harzard regression model analysis, tumor size, capsule status, vascular invasion, and p53 expression were independent factors that were closely related to the overall survival (OS) rates of HCC patients. The survival rates of patients with 3+ for p53 expression were much lower than those with 2+ or + for p53 expression. Only vascular invasion (P < 0.05) and capsule (P < 0.01) were closely related to the disease-free survival (DFS) of HCC patients. In multivariate analysis, p53 overexpression (RI 0.5456, P < 0.01) was the most significant factor associated with the OS rates of patients after HCC resection, while tumor size (RI 0.5209, P < 0.01), vascular invasion (RI 0.5271, P < 0.01) and capsule (RI 0.8691, P < 0.01) were also related to the OS. However, only tumor capsular status was an independent predictive factor (P < 0.05) for the DFS. No significant prognostic value was found in PCNA-LI, Edmondson’s grade, patients’ sex and preoperative serum AFP level.

CONCLUSION: Accumulation of p53 expression, as well as tumor size, capsule and vascular invasion, could be valuable markers for predicting the prognosis of HCC patients after resection. The quantitative immunohistochemical scoring for p53 nuclear accumulation might be more valuable for predicting prognosis of patients after HCC resection than the common qualitative analysis.

Inhibitory effect of endostatin expressed by human liver carcinoma SMMC7721 on endothelial cell proliferation in vitro

AIM: To construct a stable transfectant of human liver carcinoma cell line SMMC7721 that could secret human endostatin and to explore the effect of human endostatin expressed by the transfectant on endothelial cell proliferation.

METHODS: Recombinant retroviral plasmid pLncx-Endo containing the cDNA for human endostain gene together with rat albumin signal peptide was engineered and transferred into SMMC7721 cell by lipofectamine. After selection with G418, endostatin-transfected SMMC7721 cells were chosen and expanded. Immunohistochemical staining and Western blot were used to detect the expression of human endostatin in transfected SMMC7721 cells and its medium. The conditioned medium of endostatin-transfected and control SMMC7721 cells were collected to cultivate with human umbilical vein endothelial cells for 72 h. The inhibitory effect of endostatin, expressed by transfected SMMC7721 cells, on endothelial proliferation in vitro was observed by using MTT assay.

RESULTS: A 550 bp specific fragment of endostatin gene was detected from the PCR product of endostatin-transfected SMMC7721 cells. Immunohistochemistry and Western blot analysis confirmed the expression and secretion of foreigh human endostatin protein by endostatin-transfected SMMC7721 cells. In vitro endothelial proliferation assay showed that 72 h after cultivation with human umbilical vein endothelial cells, the optical density (OD) in group using the medium from endostatin-transfected SMMC7721 cells was 0.51 ± 0.06, lower than that from RPMI 1640 group (0.98 ± 0.09) or that from control plasmid pLncx-transfected SMMC7721 cells (0.88 ± 0.11). The inhibitory rate for medium from endostatin-transfected SMMC7721 cells was 48%, significantly higher than that from empty plasmid pLncx-transfected SMMC7721 cells (10.2%, P < 0.01).

CONCLUSION: Human endostatin can be stably expressed by SMMC7721 cell transferred with human endostain gene and its product can significantly inhibit the proliferation of human umbilical vein endothelial cell in vitro.