Rapid and cost-effective xenograft hepatocellular carcinoma model in Zebrafish for drug testing

New Progress in Zebrafish Liver Tumor Models: Techniques and Applications in Hepatocellular Carcinoma Research

Liver tumors represent a serious clinical health problem that threatens human life. Previous studies have demonstrated that the pathogenesis of liver tumors is complex and influenced by various factors, highlighting limitations in both basic pathological research and clinical treatment. Traditional research methods often begin with the discovery of phenomena and gradually progress to the development of animal models and human trials. Among these, liver tumor animal models play a critical role in advancing related research. The zebrafish liver closely resembles the human liver in structure, function, and regenerative capacity. Additionally, the high transparency and rapid development of zebrafish embryos and larvae make them ideal model organisms for studying liver tumors. This review systematically summarizes recent methods for constructing zebrafish liver tumor models, including transplantation, transgenesis, induction, and gene knockout. Furthermore, the present paper explores the applications of these models in the study of liver cancer pathogenesis, metastasis, the tumor microenvironment, drug screening, and other related areas. By comparing the advantages and limitations of various models and integrating their distinct characteristics, this review provides insights for developing a novel liver tumor model that better aligns with clinical needs. This approach will offer valuable reference information for further in-depth studies of the pathological mechanisms of liver tumors and the development of new therapeutic drugs or strategies.

Zebrafish as an Experimental Model for Human Disease

Belonging to the family of Cyprinidae, the zebrafish is a small freshwater fish present in the rivers of Bangladesh, Northern India and Southern Nepal [...].

Trabectedin impairs invasiveness and metastasis in adrenocortical carcinoma preclinical models

The pharmacological approach to adrenocortical carcinoma (ACC) is based on mitotane with/without etoposide, doxorubicin, and cisplatin, according to the disease stage. Considering the limited efficacy and toxicity of this treatment, new strategies are required. Trabectedin is a marine-derivated antitumoral agent that inhibits oncogenic transcription. We have already demonstrated trabectedin cytotoxic activity at sub-nanomolar concentrations in ACC cells. Here, we expanded the investigation of trabectedin effect on ACC preclinical models, evaluating whether trabectedin could affect ACC cells' invasiveness and metastasis formation. NCI-H295R, MUC-1, and TVBF-7 cell lines were used. Cell tumor xenografts in Danio rerio embryos were performed. The tumor mass areas and the number of embryos with metastasis were evaluated. The in vitro invasiveness of cells was evaluated. Effects of trabectedin of MMP2, TIMP1, and TIMP2 were evaluated at gene level qRT-PCR. MMP2 secreted in the cell medium was evaluated by Western blot and by zymography. Xenograft experiments demonstrated that trabectedin significantly reduced the tumor area in each ACC cell model and metastasis formation in embryos injected with metastasis-derived cell lines. Trabectedin treatment reduced the invasiveness of ACC cells across the matrix, which was greater at baseline for the metastatic models. In metastatic cell models, protein analysis demonstrated a reduction of MMP2 secretion and activity in the culture medium after treatment. Our results indicate that trabectedin interferes with invasiveness and metastasis processes, both dramatic features of ACC. Furthermore, these results support those previously published in providing the rationale for a clinical evaluation of the efficacy of trabectedin in ACC patients.

Using a zebrafish xenograft tumor model to compare the efficacy and safety of VEGFR-TKIs

PURPOSE

We constructed a zebrafish xenograft tumor model to compare and quantify the antiangiogenic efficacy and safety of nine vascular endothelial growth factor receptor-tyrosine kinase inhibitors (VEGFR-TKIs), axitinib, lenvatinib, pazopanib, apatinib, cabozantinib, sunitinib, semaxanib, sorafenib, and regorafenib, in parallel.

METHODS

CT26 and GL261 tumor cells were implanted into the perivitelline space of Tg (flk1: eGFP) zebrafish to construct a xenograft tumor model. VEGFR-TKIs' antiangiogenic efficacy was quantified using AngioTool software, and the median effective dose (ED50) was calculated. The toxicity was evaluated by calculating the median lethal dose (LD50) and gross morphological changes. Cardiac toxicity was further assessed by heart rate, heart rhythm, the distance between the sinus venosus (SV) and bulbus arteriosus (BA), and pericardial edema.

RESULTS

Using the zebrafish xenograft tumor model, we found that all nine VEGFR-TKIs exhibited antiangiogenic abilities, but the effectiveness of semaxanib was worse than that of other VEGFR-TKIs. Meanwhile, the zebrafish toxicity assay showed that all tested VEGFR-TKIs were associated with cardiac-related toxicity, especially apatinib and axitinib, which caused serious pericardial edema in zebrafish at relatively low concentrations. A narrow therapeutic window was found for most VEGFR-TKIs, and the simultaneous occurrence of toxic effects of semaxanib was recognized.

CONCLUSION

Our findings showed the potential of using a zebrafish xenograft tumor model to accelerate VEGFR-TKI screening and further the development of more efficient and less toxic VEGFR-TKIs.

5-Azacytidine Downregulates the Proliferation and Migration of Hepatocellular Carcinoma Cells In Vitro and In Vivo by Targeting miR-139-5p/ROCK2 Pathway

Simple Summary

For hepatocellular carcinoma (HCC), the second most common cause of cancer-related death, effective therapeutic approaches are lacking. As aberrant gene methylation is a major contributor to the development of HCC, demethylating drugs such as 5-azacytidine (5-Aza) have been proposed. However, despite the potential efficacy of 5-Aza in HCC, most of its mechanisms of action are still unknown. Here, we investigate the phenotypic/molecular effects of 5-Aza with a focus on miR-139-5p. Using multiple in vitro and in vivo models of HCC, we show for the first time that 5-Aza can impair HCC development via upregulation of miR-139-5p, which in turn downregulates the ROCK2/cyclin D1/E2F1/cyclin B1 pro-proliferative pathway and the ROCK2/MMP-2 pro-migratory pathway. These observations elucidate the mechanisms of action of 5-Aza in HCC, strengthen its therapeutic potential, and provide novel information about the crosstalk among ROCK2/cyclin D1/E2F1/cyclin B1/MMP-2 in HCC.

Abstract

Background: For hepatocellular carcinoma (HCC), effective therapeutic approaches are lacking. As aberrant gene methylation is a major contributor to HCC development, demethylating drugs such as 5-azacytidine (5-Aza) have been proposed. As most 5-Aza mechanisms of action are unknown, we investigated its phenotypic/molecular effects. Methods: 5-Aza effects were examined in the human HCC cell lines JHH-6/HuH-7 and in the rat cell-line N1-S1. We also employed a xenograft mouse model (HuH-7), a zebrafish model (JHH-6), and an orthotopic syngeneic rat model (N1-S1) of HCC. Results: 5-Aza downregulated cell viability/growth/migration/adhesion by upregulating miR-139-5p, which in turn downregulated ROCK2/cyclin D1/E2F1 and increased p27^kip1, resulting in G1/G0 cell accumulation. Moreover, a decrease in cyclin B1 and an increase in p27^kip1 led to G2/M accumulation. Finally, we observed a decrease in MMP-2 levels, a stimulator of HCC cell migration. Aza effects were confirmed in the mouse model; in the zebrafish model, we also demonstrated the downregulation of tumor neo-angiogenesis, and in the orthotopic rat model, we observed impaired N1-S1 grafting in a healthy liver. Conclusion: We demonstrate for the first time that 5-Aza can impair HCC development via upregulation of miR-139-5p, which in turn impairs the ROCK2/cyclin D1/E2F1/cyclin B1 pro-proliferative pathway and the ROCK2/MMP-2 pro-migratory pathway. Thus, we provide novel information about 5-Aza mechanisms of action and deepen the knowledge about the crosstalk among ROCK2/cyclin D1/E2F1/cyclin B1/p27^kip1/MMP-2 in HCC.

Zebrafish Xenotransplantation Models for Studying Gene Function and Drug Treatment in Hepatocellular Carcinoma

INTRODUCTION

Zebrafish is a promising model organism for human disease including hepatocellular cancer (HCC). Recently, zebrafish has emerged also as a host for xenograft studies of liver cancer cell lines and patient derived tumors of HCC. Zebrafish embryos enable drug screening and gene function studies of xenografted cells via ease of microinjection and visualization of tumor growth and metastasis.

OBJECTIVES

In this review, we aimed to overview zebrafish HCC and liver cancer xenotransplantation studies focusing on 'gene functional analysis' and 'drug/chemical screening'.

METHODS

Herein, a comprehensive literature search was performed for liver and HCC xenografts in zebrafish on PubMed using different key words and filters for molecular modifications or drug exposure.

RESULTS

Our literature search revealed around 250 studies which were filtered and summarized in a table (Table 1) revealing comprehensive collection of experimental and technical details on microinjection, injected cell lines, molecular modifications of injected cells, types and doses of drug treatments as well as biological assessments.

CONCLUSION

This review provides a platform for HCC and liver xenografts and highlights studies performed to understand gene functionality and drug efficacy in vivo in zebrafish.

A versatile, automated and high-throughput drug screening platform for zebrafish embryos

Zebrafish provide a unique opportunity for drug screening in living animals, with the fast-developing, transparent embryos allowing for relatively high-throughput, microscopy-based screens. However, the limited availability of rapid, flexible imaging and analysis platforms has limited the use of zebrafish in drug screens. We have developed an easy-to-use, customisable automated screening procedure suitable for high-throughput phenotype-based screens of live zebrafish. We utilised the WiScan® Hermes High Content Imaging System to rapidly acquire brightfield and fluorescent images of embryos, and the WiSoft® Athena Zebrafish Application for analysis, which harnesses an Artificial Intelligence-driven algorithm to automatically detect fish in brightfield images, identify anatomical structures, partition the animal into regions and exclusively select the desired side-oriented fish. Our initial validation combined structural analysis with fluorescence images to enumerate GFP-tagged haematopoietic stem and progenitor cells in the tails of embryos, which correlated with manual counts. We further validated this system to assess the effects of genetic mutations and X-ray irradiation in high content using a wide range of assays. Further, we performed simultaneous analysis of multiple cell types using dual fluorophores in high throughput. In summary, we demonstrate a broadly applicable and rapidly customisable platform for high-content screening in zebrafish. This article has an associated First Person interview with the first author of the paper.

Xenograft Zebrafish Models for the Development of Novel Anti-Hepatocellular Carcinoma Molecules

Hepatocellular carcinoma (HCC) is the sixth most common type of tumor and the second leading cause of tumor-related death worldwide. Liver cirrhosis is the most important predisposing factor for HCC. Available therapeutic approaches are not very effective, especially for advanced HCC, which is the most common form of the disease at diagnosis. New therapeutic strategies are therefore urgently needed. The use of animal models represents a relevant tool for preclinical screening of new molecules/strategies against HCC. However, several issues, including animal husbandry, limit the use of current models (rodent/pig). One animal model that has attracted the attention of the scientific community in the last 15 years is the zebrafish. This freshwater fish has several attractive features, such as short reproductive time, limited space and cost requirements for husbandry, body transparency and the fact that embryos do not show immune response to transplanted cells. To date, two different types of zebrafish models for HCC have been developed: the transgenic zebrafish and the zebrafish xenograft models. Since transgenic zebrafish models for HCC have been described elsewhere, in this review, we focus on the description of zebrafish xenograft models that have been used in the last five years to test new molecules/strategies against HCC.

Mass spectrometry imaging in zebrafish larvae for assessing drug safety and metabolism

Drug safety assessment in the early phases of drug discovery is critical to facilitate the rapid development of novel therapeutics. Recently, teleost zebrafish (Danio rerio) has emerged as a promising vertebrate model for the assessment of drug safety. Zebrafish is a convenient model because of its small size, high fecundity, embryo transparency, and ex utero development. In this study, we developed a matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) method applied to zebrafish larvae to investigate safety and metabolism of sahaquine (Sq), an anticancer agent inhibiting histone deacetylase 6. This technique improves on prior studies using liquid chromatography-mass spectrometry (LC-MS) by adding analysis of the drug spatial distribution. Using this method, it was determined that Sq dissolved in fish water (1-2000 μM) did not reach the larval body and was mainly distributed throughout the yolk. High Sq concentration (800 μM) administered intravenously allowed the compound to reach the larval body but did not induce phenotypic abnormalities. Sq was metabolized into its glucuronidated form within 24 h and was excreted within 72 h. MALDI MSI was instrumental in showing that Sq-glucuronide was mainly formed in the gut and slightly in yolk syncytial layer, and provided valuable insights into xenobiotics elimination in zebrafish larvae. This study indicates that Sq has a good safety profile and merits further investigations in other disease models. In addition, the optimized MALDI MSI protocol provided here can be widely applied to study distribution and metabolic fate of other structurally related molecules.

Morphological Abnormalities and Gene Expression Changes Caused by High Incubation Temperatures in Zebrafish Xenografts with Human Cancer Cells

Published studies show that most of the human cancer xenograft studies in zebrafish embryos have used incubation temperatures in the range of 32–34 °C for 3–6 days post-injection, trying to find a compromise temperature between the zebrafish embryos (28 °C) and the human injected cells (37 °C). While this experimental setup is widely used, a question remains: is possible to overcome the drawbacks caused by a suboptimal temperature for the injected cells? To clarify the effect of temperature and injected cells on the host, in this study, we analyzed the development and health of the last in response to different temperatures in the presence or absence of injected human cancer cells. Comparing different incubation temperatures (28, 34 and 36 °C), we determined morphological abnormalities and developmental effects in injected and non-injected embryos at different time points. Besides this, the expression of selected genes was determined by qPCR to determine temperature affected metabolic processes in the embryos. The results indicate that an incubation temperature of 36 °C during a period of 48 h is suitable for xenotransplantation without morphological or metabolic changes that could be affecting the host or the injected cells, allowing them to proliferate near their optimal temperature.

Extra-Intestinal Effects of C. difficile Toxin A and B: An In Vivo Study Using the Zebrafish Embryo Model

C.difficile infection (CDI) is not a merely “gut-confined” disease as toxemia could drive the development of CDI-related extra-intestinal effects. These effects could explain the high CDI-associated mortality, not just justified by diarrhea and dehydration. Here, the extra-intestinal effects of toxin A (TcdA) and B (TcdB) produced by C. difficile have been studied in vivo using the zebrafish embryo model. Noteworthy, protective properties of human serum albumin (HSA) towards toxins-induced extra-intestinal effects were also addressed. Zebrafish embryos were treated with TcdA, TcdB and/or HSA at 24 h post-fertilization. Embryos were analyzed for 48 h after treatment to check vital signs and morphological changes. Markers related to cardio-vascular damage and inflammation were evaluated by Real-Time quantitative PCR and/or western blotting. Both toxins induced cardiovascular damage in zebrafish embryos by different mechanisms: (i) direct toxicity (i.e., pericardial edema, cardiac chambers enlargement, endothelial alteration); (ii) increased hormonal production and release (i.e., atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP)), (iii) alteration of the vascular system through the increase of the vascular endothelial growth factor (VEGF-A) levels, as well as of its receptors, (iv) pro-inflammatory response through high cytokines production (i.e., CXCL8, IL1B, IL6 and TNFα) and (v) cell-mediated damage due to the increase in neutrophils number. In addition to cardiovascular damage, we observe skin alteration and inflammation. Finally, our data indicate a protective effect of HSA toward the toxins induced extra-intestinal effects. Together, our findings can serve as a starting point for humans’ studies to substantiate and understand the extra-intestinal effects observed in CDI patients.

MicroRNAs in Animal Models of HCC

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related mortality. Molecular heterogeneity and absence of biomarkers for patient allocation to the best therapeutic option contribute to poor prognosis of advanced stages. Aberrant microRNA (miRNA) expression is associated with HCC development and progression and influences drug resistance. Therefore, miRNAs have been assayed as putative biomarkers and therapeutic targets. miRNA-based therapeutic approaches demonstrated safety profiles and antitumor efficacy in HCC animal models; nevertheless, caution should be used when transferring preclinical findings to the clinics, due to possible molecular inconsistency between animal models and the heterogeneous pattern of the human disease. In this context, models with defined genetic and molecular backgrounds might help to identify novel therapeutic options for specific HCC subgroups. In this review, we describe rodent models of HCC, emphasizing their representativeness with the human pathology and their usefulness as preclinical tools for assessing miRNA-based therapeutic strategies.

Adrenocortical Carcinoma Xenograft in Zebrafish Embryos as a Model To Study the In Vivo Cytotoxicity of Abiraterone Acetate

Abiraterone acetate (AbiAc) inhibits tumor growth when administered to immunodeficient mice engrafted with the in vitro cell model of human adrenocortical carcinoma (ACC). Here, we developed and validated a zebrafish model engrafted with cortisol-secreting ACC cells to study the effects of AbiAc on tumor growth. The experimental conditions for AbiAc absorption in AB zebrafish embryos including embryo number, AbiAc concentration, and absorption time curve by liquid chromatography-tandem mass spectrometry were set up. The AbiAc effect on steroid production in AB zebrafish embryos was measured as well. ACC cells (the NCI-H295R cell line, the primary cell ACC29, and the negative control cell SW13) were treated with drug-induced liver injury fluorescent dye, and ∼240 cells per 4 nL was injected in the subperidermal space of the yolk sac of AB zebrafish embryos (n = 80 ± 10). The cell area was measured with Noldus DanioScopeTM software. AbiAc absorption in AB zebrafish embryos was stage dependent. Abiraterone (Abi) concentration decreased, whereas its main metabolite, Δ4A, increased. Accordingly, we demonstrated that zebrafish expressed mRNA encoding the enzyme 3β-hydroxysteroid dehydrogenase, which converts Abi in Δ4A. Furthermore, ABiAc reduced cortisol production and increased progesterone in zebrafish embryos. Three days after cell injection, the cortisol-secreting ACC cell area in solvent-treated embryos was significantly higher than that in 1 µM AbiAC‒treated embryos, whereas no AbiAc effect was observed in SW13 cells, which lack the Abi target enzyme CYP17A1.Zebrafish embryos xenografted with ACC tumor cells could be a useful, fast, and reproducible experimental model to preclinically test the activity of new drugs in human ACC.

PCR-based zebrafish model for personalised medicine in head and neck cancer

BACKGROUND

Currently, in vivo model for personalised cancer drug testing is challenging. A zebrafish larvae xenograft model has been applied in recent years to cancer research, particularly for drug testing purposes, showing promising results in drug testing against patient-derived tumour xenografts. Currently, these xenograft models apply imaging techniques to measure drug efficacy. However, this method carries several limitations, including timely imaging, thereby reducing the available number of tested fish and drugs. Here, we propose a PCR-based fast assay to evaluate drug efficacy in a zebrafish larvae xenograft model.

METHODS

We tested two primary and corresponding metastatic head and neck squamous cell carcinoma (HNSCC) cell lines and patient-derived tongue cancer sample applying zebrafish larvae xenograft model. Cisplatin efficacy was tested using imaging technique and compared the results with PCR-based methods. Drug screening of eight compounds was applied on both cell lines and patient sample using PCR.

RESULTS

In a head-to-head comparison, all the three techniques (imaging, quantitative PCR, and droplet digital PCR) showed similar reduction of the cancer cells growth after cisplatin treatment. Using the quantitative PCR assay, we demonstrated a dose-dependent response of HNSCC cells to cisplatin. Drug screening results of four HNSCC cell lines and patient sample revealed different drug efficacy between tested cancer cells.

CONCLUSION

We introduce a novel, easy, fast and cost-effective PCR-based in vivo zebrafish larvae assay to test the response of cell lines and clinical tumour samples to anti-cancer drugs. This method goes hand-by-hand with the commonly used imaging assay.

HMGA1 promotes breast cancer angiogenesis supporting the stability, nuclear localization and transcriptional activity of FOXM1

Background

Breast cancer is the most common malignancy in women worldwide. Among the breast cancer subtypes, triple-negative breast cancer (TNBC) is the most aggressive and the most difficult to treat. One of the master regulators in TNBC progression is the architectural transcription factor HMGA1. This study aimed to further explore the HMGA1 molecular network to identify molecular mechanisms involved in TNBC progression.

Methods

RNA from the MDA-MB-231 cell line, silenced for HMGA1 expression, was sequenced and, with a bioinformatic analysis, molecular partners HMGA1 could cooperate with in regulating common downstream gene networks were identified. Among the putative partners, the FOXM1 transcription factor was selected. The relationship occurring between HMGA1 and FOXM1 was explored by qRT-PCR, co-immunoprecipitation and protein stability assays. Subsequently, the transcriptional activity of HMGA1 and FOXM1 was analysed by luciferase assay on the VEGFA promoter. The impact on angiogenesis was assessed in vitro, evaluating the tube formation ability of endothelial cells exposed to the conditioned medium of MDA-MB-231 cells silenced for HMGA1 and FOXM1 and in vivo injecting MDA-MB-231 cells, silenced for the two factors, in zebrafish larvae.

Results

Here, we discover FOXM1 as a novel molecular partner of HMGA1 in regulating a gene network implicated in several breast cancer hallmarks. HMGA1 forms a complex with FOXM1 and stabilizes it in the nucleus, increasing its transcriptional activity on common target genes, among them, VEGFA, the main inducer of angiogenesis. Furthermore, we demonstrate that HMGA1 and FOXM1 synergistically drive breast cancer cells to promote tumor angiogenesis both in vitro in endothelial cells and in vivo in a zebrafish xenograft model. Moreover, using a dataset of breast cancer patients we show that the co-expression of HMGA1, FOXM1 and VEGFA is a negative prognostic factor of distant metastasis-free survival and relapse-free survival.

Conclusions

This study reveals FOXM1 as a crucial interactor of HMGA1 and proves that their cooperative action supports breast cancer aggressiveness, by promoting tumor angiogenesis. Therefore, the possibility to target HMGA1/FOXM1 in combination should represent an attractive therapeutic option to counteract breast cancer angiogenesis.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1307-8) contains supplementary material, which is available to authorized users.

In vivo toxicity assays in zebrafish embryos: a pre-requisite for xenograft preclinical studies

The human cancer cell xenograft in zebrafish embryos has become a very useful preclinical tool in oncology research. While many anticancer drugs have been assayed with this model, few studies regarding the toxicity limits of these drugs for the host have been addressed. Here, we evaluated the acute toxicity of five approved and routinely used human anticancer drugs embracing different mechanism action types: Carboplatin (CarboPt), Irinotecan (IT), Doxorubicin (DOX), Paclitaxel (PT) and Chloroquine (CQ). They were tested in zebrafish embryos using the Fish Embryo Acute Toxicity (FET) test at 0 and 72 hours per fertilization (hpf). Additionally, we compared those results with in vitro toxicity assays and could find notable differences between both models. Our results indicate that the toxicity data of a compound evaluated in vitro and in a FET test at 0 hpf do not guarantee a reliable toxicity determination for performing xenografts in zebrafish, being necessary additional toxicity studies using 72 hpf embryos, the starting point of drug treatment in this kind of preclinical assays.

An efficient method to generate xenograft tumor models of acute myeloid leukemia and hepatocellular carcinoma in adult zebrafish

Zebrafish is emerging as a promising model for the study of human cancers. Several xenograft models of zebrafish have been developed, particularly in larval stages (<48 h post fertilization) when the immune system of fish is not developed. However, xenografting in adult zebrafish requires laborious and transient methods of immune suppression (γ- irradiation or dexamethasone) that limits engraftment and survival of the tumor or fail to recapitulate specific characteristics of malignancies. Thus, the availability of a simple protocol to successfully engraft adult zebrafish, remains a challenge. The current study addresses this limitation and describes a robust method of xenografting in adult zebrafish. We describe a protocol that involves pre-conditioning of Casper, a pigmentation mutant of zebrafish with busulfan that led to a higher rate of engraftment of hepatocellular carcinoma and acute myeloid leukemia cells. To further ascertain the homing characteristics of the injected cancer cells, we transplanted adult zebrafish by two routes of administration and then studied their compartmentalization. This model presents a valuable alternative to rodents to study the biology of these cancers and also a cost-effective platform for evaluation of potential anti-cancer agents.

Cell-autonomous and cell non-autonomous downregulation of tumor suppressor DAB2IP by microRNA-149-3p promotes aggressiveness of cancer cells

The tumor suppressor DAB2IP contributes to modulate the network of information established between cancer cells and tumor microenvironment. Epigenetic and post-transcriptional inactivation of this protein is commonly observed in multiple human malignancies, and can potentially favor progression of tumors driven by a variety of genetic mutations. Performing a high-throughput screening of a large collection of human microRNA mimics, we identified miR-149-3p as a negative post-transcriptional modulator of DAB2IP. By efficiently downregulating DAB2IP, this miRNA enhances cancer cell motility and invasiveness, facilitating activation of NF-kB signaling and promoting expression of pro-inflammatory and pro-angiogenic factors. In addition, we found that miR-149-3p secreted by prostate cancer cells induces DAB2IP downregulation in recipient vascular endothelial cells, stimulating their proliferation and motility, thus potentially remodeling the tumor microenvironment. Finally, we found that inhibition of endogenous miR-149-3p restores DAB2IP activity and efficiently reduces tumor growth and dissemination of malignant cells. These observations suggest that miR-149-3p can promote cancer progression via coordinated inhibition of DAB2IP in tumor cells and in stromal cells.

Development of a novel zebrafish xenograft model in ache mutants using liver cancer cell lines

Acetylcholinesterase (AChE), an enzyme responsible for degradation of acetylcholine, has been identified as a prognostic marker in liver cancer. Although in vivo Ache tumorigenicity assays in mouse are present, no established liver cancer xenograft model in zebrafish using an ache mutant background exists. Herein, we developed an embryonic zebrafish xenograft model using epithelial (Hep3B) and mesenchymal (SKHep1) liver cancer cell lines in wild-type and ache sb55 sibling mutant larvae after characterization of cholinesterase expression and activity in cell lines and zebrafish larvae. The comparison of fluorescent signal reflecting tumor size at 3-days post-injection (dpi) revealed an enhanced tumorigenic potential and a reduced migration capacity in cancer cells injected into homozygous ache sb55 mutants when compared with the wild-type. Increased tumor load was confirmed using an ALU based tumor DNA quantification method modified for use in genotyped xenotransplanted zebrafish embryos. Confocal microscopy using the Huh7 cells stably expressing GFP helped identify the distribution of tumor cells in larvae. Our results imply that acetylcholine accumulation in the microenvironment directly or indirectly supports tumor growth in liver cancer. Use of this model system for drug screening studies holds potential in discovering new cholinergic targets for treatment of liver cancers.

Inducible liver-specific overexpression of gankyrin in zebrafish results in spontaneous intrahepatic cholangiocarcinoma and hepatocellular carcinoma formation

Liver cancer is the second leading cause of death worldwide. As such, establishing animal models of the disease is important for both basic and translational studies that move toward developing new therapies. Gankyrin is a critical oncoprotein in the genetic control of liver pathology. In order to evaluate the oncogenic role of gankyrin without cancer cell inoculation and drug treatment, we overexpressed gankyrin under the control of the fabp10a promoter. A Tet-Off system was used to drive expression in hepatocytes. At seven to twelve months of age, gankyrin transgenic fish spontaneously incurred persistent hepatocyte damage, steatosis, cholestasis, cholangitis, fibrosis and hepatic tumors. The tumors were both hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC). ICC is the second most frequent primary liver cancer in human patients and the first to develop in this tumor model. We further investigated the role of complement C3, a central molecule of the complement system, and found the expression levels of both in mRNA and protein are decreased during tumorigenesis. Together, these findings suggest that gankyrin can promote malignant transformation of liver cells in the context of persistent liver injury. This transformation may be related to compensatory proliferation and the inflammatory microenvironment. The observed decrease in complement C3 may allow transforming cells to escape coordinated induction of the immune response. Herein, we demonstrate an excellent zebrafish model for liver cancers that will be useful for studying the molecular mechanisms of tumorgenesis.

Dissecting the role of the elongation factor 1A isoforms in hepatocellular carcinoma cells by liposome-mediated delivery of siRNAs

Eukaryotic elongation factor 1A (eEF1A), a protein involved in protein synthesis, has two major isoforms, eEF1A1 and eEF1A2. Despite the evidences of their involvement in hepatocellular carcinoma (HCC), the quantitative contribution of each of the two isoforms to the disease is unknown. We depleted the two isoforms by means of siRNAs and studied the effects in three different HCC cell lines. Particular care was dedicated to select siRNAs able to target each of the two isoform without affecting the other one. This is not a trivial aspect due to the high sequence homology between eEF1A1 and eEF1A2. The selected siRNAs can specifically deplete either eEF1A1 or eEF1A2. This, in turn, results in an impairment of cell vitality, growth and arrest in the G1/G0 phase of the cell cycle. Notably, these effects are quantitatively superior following eEF1A1 than eEF1A2 depletion. Moreover, functional tests revealed that the G1/G0 block induced by eEF1A1 depletion depends on the down-regulation of the transcription factor E2F1, a known player in HCC. In conclusion, our data indicate that the independent targeting of the two eEF1A isoforms is effective in reducing HCC cell growth and that eEF1A1 depletion may result in a more evident effect.