Rat Model Of Hepatocellular Carcinoma Research Articles

The changes of sera IGF-II and VEGF concentrations before and after microwave ablation treat-ment in rat models of bepatoceilular carcinoma

Objective To study change of IGF- Ⅱ , VEGF, IL-2 and IFN-γ before and after microwave ablation in rat models of hepatocellular carcinoma （HCC）. Methods Eighty SD rats were randomly divided into 4 groups as follows ： normal group, control group, microwave ablation group and surgical operation group. The HCC models were established in control group, microwave ablation group and surgical operation group. The microwave ablation group and surgical operation group accepted microwave ablation and surgical operation respectively. The serum concentrations of IGF-Ⅱ , VEGF, IL-2 and IFN-γ were determined by ELISA. IGF-Ⅱ, VEGF, IL-2, AFP and IFN-γ concentrations between the normal and control groups were compared after treatment for 3 weeks. Results In control group, sera concentrations of IGF- Ⅱ（ 1.93± 0.45 vs 1.16 ± 0. 21 ）μg/L, and VEGF （395.72 ± 55.28 vs 248.43 ±41.71 ） ng/L on the 5th week were significantly higher than those on the 3rd week （ P 〈 0.05 ）. After microwave ablation or surgical operation, concentrations of IGF- Ⅱ （0.65 ±0.18 vs 0. 73 ±0.16） μg/L and VEGF （ 129.35 ±51.46 vs 135.63 ± 33.37） ng/L were significantly decreased,but IL-2, and IFN-γ concentrations significantly increased as compared with control group. Conclusion IGF- Ⅱ can promote tumor angiogenesis directly or by increasing the synthesis of VEGF. It could be an important index in diagnosis, prognosis and tracking of primary HCC. Microwave ablation is an effective method in the treatment of HCC. Key words: Carcinoma, hepatocellular; Insulin like growth factor; Vascular endothelial cell growth factor; Cytokine ; Microwave ablation

Silibinin inhibits CYP2E1‐dependent ethanol metabolism, oxidative stress and cell proliferation in a rat model of hepatocellular carcinoma (HCC)

Many deleterious effects of ethanol (EtOH) are attributed to oxidative stress following metabolism, generating renewed interest in anti‐oxidants as potential therapeutic agents. Previous studies have identified EtOH metabolism as important in regulating EtOH‐dependent increases in cell proliferation using a rat model of hepatocellular carcinoma (HCC). The aim of the current study was to determine the effect of silibinin (a flavinoligand derived from Silymarin marianum) on ethanol metabolism, oxidative stress and cell proliferation using an H4IIE cell culture model of HCC. Exposure of H4IIE cells to EtOH lead to dose‐dependent increases in CYP2E1 protein expression in the absence of significant changes in acetaldehyde or aldehyde dehydrogenase (ADH/ALDH) expression. These data revealed significantly increased EtOH metabolism, oxidative stress/lipid peroxidation in H4IIE cells exposed to EtOH in the absence of silibinin. Treatment of H4IIE cells with silibinin prior to EtOH abrogated the effects of ethanol on CYP2E1 expression with no evident change in ADH/ALDH. In doing so silibinin significantly decreased the rate of EtOH metabolism, oxidative stress and, EtOH‐dependent HCC proliferation. In conclusion, these data demonstrate silibinin inhibits EtOH‐dependent CYP2E1 induction in HCC cells thereby inhibiting the effect of EtOH on HCC mitogenesis. This research was funded by NIH‐grants AA‐16858 (IHM) & AA14891 (LWS).

Expression and Correlation of Hypoxia-inducible Factor-1α, Vascular Endothelial Growth Factor and Microvessel Density in Experimental Rat Hepatocarcinogenesis

An experimental rat hepatocellular carcinoma (HCC) model was established using diethylnitrosamine and N-nitrosomorpholine to induce carcinogenesis in Sprague-Dawley rats. During hepatocarcinogenesis, seven rats were sacrificed at 0, 4, 8, 12 and 16 weeks and 10 rats were sacrificed at 20 weeks. The levels of hypoxia-inducible factor-1alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF) protein and mRNA were examined by immunohistochemistry, Western blot and semi-quantitative reverse transcriptase-polymerase chain reaction at different stages in the rat HCC model. Twenty weeks after induction of hepatocarcinogenesis, the expression of HIF-1alpha and VEGF protein and mRNA significantly increased compared with week 0. Microvessel density (MVD) increased considerably once liver cancer developed. There was a significant positive correlation between MVD and both HIF-1alpha and VEGF, and between HIF-1alpha and VEGF levels. These results suggest that HIF-1alpha and VEGF play important roles in tumour occurrence and development during rat hepatocarcinogenesis, possibly through promoting tumour angiogenesis.

Prevention of hepatic tumor growth and metastasis in rats with rapamycin

To test the effect of rapamycin (RAPA) on hepatic tumor growth and metastasis in Sprague-Dawley (SD) rat model and explore the possible mechanism. SD rat hepatocellular carcinoma (HCC) model with metastatic potential was induced by diethylnitrosamine (DEN) and N-nitrosomorpholine (NMOR). 120 SD rats were randomized into four groups 16 weeks after DEN and NMOR treatment, and received 4-week intraperitoneal injection of RAPA (1.5 or 4.5 mg x kg(-1) x d(-1)), CsA (25 mg x kg(-1) x d(-1)) or equal volume of 0.9% saline, respectively. Tumor growth and metastasis were checked after the 4-week treatment. Serum vascular endothelial growth factor (VEGF) was determined by enzyme-linked immunosorbent assay (ELISA). Antiangiogenetic effects were assessed by CD34 immunostaining. The levels of hypoxia-inducible factor 1 alpha (HIF-1 alpha) and VEGF proteins and mRNAs were detected by immunohistochemistry, western blot and reverse transcriptase-polymerase chain reaction (RT-PCR). The mean liver weight (5.58% +/- 0.42% and 5.69% +/- 0.74%), the metastatic liver nodules (5.12 +/- 0.68 and 5.67 +/-1.12), the metastasis lung nodules (0.43 +/- 0.11 and 0.45 +/- 0.83), and the lung metastasis rate (17.2% and 14.8%) were lower in rats treated with RAPA 1.5 mg x kg(-1) x d(-1) or 4.5 mg x kg(-1) x d(-1) than those in rats treated with saline, which were 10.42% +/- 1.86%, 12.36 +/- 3.45, 1.81 +/- 0.3 and 50.0% respectively (P < 0.01 or P < 0.05). The intratumoral microvessel density (MVD), serum VEGF, and the levels of HIF-1 alpha and VEGF were lower in RAPA-treated rats than those in control rats. However, CsA-treated rats showed an opposite trend compared with the RAPA-treated rats. RAPA can repress the expression of angiogenesis-promoting factors HIF-1 alpha and VEGF, and significantly inhibits the growth and metastasis of HCC.

The expression of B-cell translocation gene 2 in diethylnitrosamine-induced primary hepatocellular carcinoma rat model.

To investigate the expression and role of B-cell translocation gene 2(BTG2) in the carcinogenesis of hepatocellular carcinoma (HCC). Modified Diethylnitrosamine (DEN)-induced primary hepatocellular carcinoma rat model was established. The expression of BTG2, p53 and cyclinD1 was detected by RT-PCR, western blot and immunohistochemistry. The BTG2 protein was predominantly localized in the nucleus, with faint cytoplasmic staining in normal liver cells; however, it is mainly a cytoplasmic protein in HCC cells. BTG2 was over-expressed during the early stage after DEN treatment, the expression level peaked at 5 weeks and then it gradually decreased to the normal level after 16 weeks. The expression of cyclin D1 and cyclin E was increased gradually after DEN treatment, and peaked at 16 weeks and 5 weeks respectively. A significant increase in p53 was not observed until 5 weeks after DEN treatment, and it gradually decreased after 16 weeks. Decreased expression of BTG2 may be an important step in carcinogenesis of HCC. BTG2 may positively regulate p53 expression and negatively regulate cyclin D1 expression in the carcinogenesis of HCC.

Antitumoral Activity of Rapamycin Mediated Through Inhibition of HIF-1alpha and VEGF in Hepatocellular Carcinoma

Rapamycin (RAPA) inhibits tumor growth and angiogenesis in hepatocellular carcinoma (HCC). The molecular mechanism underlying the antitumoral effects of RAPA remains unclear. Here we established a chemical-induced rat HCC model to investigate the signaling pathways mediating RAPA's antitumor activity. We found that RAPA exposure significantly diminished tumor growth, angiogenesis, and metastasis of HCC. Meanwhile, the antitumor drug dramatically decreased expression of HIF-1alpha and VEGF, either at mRNA or protein levels. Moreover, the low-dose of RAPA (1.5 mg/kg/day) was effective enough to markedly inhibit tumor progression of HCC. The preliminary results suggested that the antitumoral effects of RAPA might be at least partially mediated through downregulation of HIF-1alpha and VEGF, and low-dose RAPA-based regimens exhibited a promising future in treatment of HCC.

Enhanced oncolytic potency of vesicular stomatitis virus through vector-mediated inhibition of NK and NKT cells

Recombinant oncolytic viruses represent a promising alternative option for the treatment of malignant cancers. We have reported earlier the safety and efficacy of recombinant vesicular stomatitis virus (VSV) vectors in a rat model of hepatocellular carcinoma (HCC). However, the full potential of VSV therapy is limited by a sudden decline in intratumoral virus replication observed early after viral administration, a phenomenon that coincides with an accumulation of inflammatory cells within infected lesions. To overcome the antiviral function of these cells, we present a recombinant virus, rVSV-UL141, which expresses a protein from human cytomegalovirus known to downregulate the natural killer (NK) cell-activating ligand CD155. The modified vector resulted in an inhibition of NK cell recruitment in vitro, as well as decreased intratumoral accumulations of NK and NKT cells in vivo. Administration of rVSV-UL141 through hepatic artery infusion in immune-competent Buffalo rats harboring orthotopic, multi-focal HCC lesions resulted in a one-log elevation of intratumoral virus replication over a control rVSV vector, which translated to enhance tumor necrosis and substantial prolongation of survival. Moreover, these results were achieved in the absence of apparent toxicities. The present study suggests the applicability of this strategy for the development of effective and safe oncolytic agents to treat multi-focal HCC, and potentially a multitude of other cancers, in the future.

Adenovirus‐mediated CD40L gene therapy induced both humoral and cellular immunity against rat model of hepatocellular carcinoma

Adenoviral-vector expressing CD40L (AxCAmCD40L)-mediated gene therapy was studied for treatment of hepatocellular carcinoma (HCC) using CD40 ligand (CD40L) complementary DNA in rats. The particular focus was whether humoral immunity took part in antitumor effect. When tumor cells transduced by AxCAmCD40L were implanted into the subcutaneous tissues of syngeneic rats, the tumor growth was suppressed. Intratumoral injection of AxCAmCD40L to pre-existing tumor in rats also led to significant reduction of tumor size. When tumor cells were re-implanted to prevention model rats and treatment model rats, no tumor growth was observed. Many studies to date have reported that cellular immunity induces antitumor immunity. However, the present study demonstrated that not only cellular immunity but also humoral immunity plays an essential role in a HCC model. These observations suggested that CD40L-mediated immune gene therapy for HCC was very effective treatment by activation of both cellular and humoral immune system.

Adenovirus-mediated CD40L gene therapy induced both humoral and cellular immunity against rat model of hepatocellular carcinoma

Adenovirus-mediated CD40L gene therapy induced both humoral and cellular immunity against rat model of hepatocellular carcinoma

A novel and effective hepatocyte growth factor kringle 1 domain and p53 cocktail viral gene therapy for the treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a leading cause of cancer death worldwide, yet effective therapeutic options for advanced HCC are limited. Kringle 1 domain of HGF (HGFK1) has been demonstrated as a potent anti-tumor molecule and p53 is a well established tumor suppressor. Recently we developed AAV transducing HGFK1 (AAV-HGFK1) as a gene therapy for HCC. Here we investigated the possibility of enhancing the effect of AAV-HGFK1 by combining it with Adv transducing p53 (Adv-p53). In vitro expression experiments suggested a small amount of Adv-p53 could increase the expression of AAV transgenes. AAV-HGFK1 + Adv-p53 cocktail strongly inhibited the proliferation of microvascular endothelial cell (MEC) and two HCC cell lines, Hepa1–6 and McA-RH7777. In two orthotopic mice and rat HCC models the cocktail gene therapy also significantly reduced the tumor burdens and prolonged the survival time by inhibiting tumor angiogenesis and inducing tumor cell death. Significantly, tumor metastasis was completely prevented. AAV-HGFK1 + Adv-p53 viral cocktail may be a promising cancer therapy for the treatment of HCC.

Synergistic antitumor effects of transarterial viroembolization for multifocal hepatocellular carcinoma in rats

Oncolytic virotherapy is a promising strategy for safe and effective treatment of malignancy. We have reported previously that recombinant vesicular stomatitis virus (VSV) vectors are effective oncolytic agents that can be safely administered via the hepatic artery in immunocompetent rats to treat multifocal hepatocellular carcinoma (HCC), resulting in tumor necrosis and prolonged survival. Though the results were encouraging, complete tumor regression was not observed, which led us to explore alternative approaches to further enhance the efficacy of VSV treatment. Transarterial embolization techniques have been shown to improve the efficiency and tumor selectivity of anticancer treatments. Degradable starch microspheres (DSM) are one such embolic agent that provides transient embolization of the therapeautic agent before being degraded by serum amylases. Here we demonstrate via dynamic contrast-enhanced magnetic resonance imaging that in our rat model of multifocal HCC, DSM injection into the hepatic artery results in a substantial reduction in tumor perfusion of systemically applied contrast agent. VSV, when administered in combination with DSM, results in enhanced tumor necrosis and synergistically prolongs survival when compared with VSV or DSM monotherapy. This regimen of viroembolization represents an innovative therapeutic modality that can augment the future development of transarterial oncolytic virus therapy for patients with advanced HCC.

Noninvasive radiofrequency ablation of cancer targeted by gold nanoparticles

Current radiofrequency ablation (RFA) techniques require invasive needle placement and are limited by accuracy of targeting. The purpose of this study was to test a novel non invasive radiowave machine that uses RF energy to thermally destroy tissue. Gold nanoparticles were designed and produced to facilitate tissue heating by the radiowaves. A solid state radiowave machine consisting of a power generator and transmitting/receiving couplers which transmit radiowaves at 13.56 MHz was used. Gold nanoparticles were produced by citrate reduction and exposed to the RF field either in solutions testing or after incubation with HepG2 cells. A rat hepatoma model using JM-1 cells and Fisher rats was employed using direct injection of nanoparticles into the tumor to focus the radiowaves for select heating. Temperatures were measured using a fiber-optic thermometer for real-time data. Solutions containing gold nanoparticles heated in a time- and power-dependent manner. HepG2 liver cancer cells cultured in the presence of gold nanoparticles achieved adequate heating to cause cell death upon exposure to the RF field with no cytotoxicity attributable to the gold nanoparticles themselves. In vivo rat exposures at 35 W using direct gold nanoparticle injections resulted in significant temperature increases and thermal injury at subcutaneous injection sites as compared to vehicle (water) injected controls. These data show that non invasive radiowave thermal ablation of cancer cells is feasible when facilitated by gold nanoparticles. Future studies will focus on tumor selective targeting of nanoparticles for in vivo tumor destruction.

Abstract No. 372: A Novel Rat Hepatocellular Carcinoma Model Designed for In Vivo Evaluation of Image-Guided Therapies

There is paucity of orthotopic hepatocellular carcinoma (HCC) small animal models in which to evaluate image-guided therapies. A small animal model that would allow in vivo visualization and quantification of tumor response to image-guided therapies would facilitate high-throughput cost-effective studies. To that end we assessed bioluminescence imaging (BLI), positron emission tomography (PET) and ultrasound (US) for early tumor detection and monitoring of disease progression in a novel HCC model.

Black tea polyphenols modulate xenobiotic-metabolizing enzymes, oxidative stress and adduct formation in a rat hepatocarcinogenesis model

The present study was designed to investigate the modulatory effects of black tea polyphenols (Polyphenon-B) on phase I and phase II xenobiotic-metabolizing enzymes and oxidative stress in a rat model of hepatocellular carcinoma (HCC). Liver tumours induced in male Sprague-Dawley rats by dietary administration of ρ-dimethylaminoazobenzene (DAB) increased cytochrome P450 (total and CYP1A1, 1A2 and 2B isoforms), cytochrome b5, cytochrome b5 reductase, glutathione S-transferase (GST total and GST-P isoform) and gamma-glutamyltranspeptidase (GGT) with decrease in quinone reductase (QR). This was accompanied by enhanced lipid and protein oxidation and compromised antioxidant defences associated with increased expression of the oxidative stress markers 4-hydroxynonenal (4-HNE), anti-hexanoyl lysine (HEL), dibromotyrosine (DiBrY) and 8-hydroxy 2-deoxyguanosine (8-OHdG). Dietary administration of Polyphenon-B effectively suppressed DAB-induced hepatocarcinogenesis, as evidenced by reduced preneoplastic and neoplastic lesions, modulation of xenobiotic-metabolizing enzymes and amelioration of oxidative stress. Thus, it can be concluded that Polyphenon-B acts as an effective chemopreventive agent by modulating xenobiotic-metabolizing enzymes and mitigating oxidative stress in an in vivo model of hepatocarcinogenesis.

Dehydroepiandrosterone supplement increases malate dehydrogenase activity and decreases NADPH-dependent antioxidant enzyme activity in rat hepatocellular carcinogenesis

Beneficial effects of dehydroepiandrosterone (DHEA) supplement on age-associated chronic diseases such as cancer, cardiovascular disease, insulin resistance and diabetes, have been reported. However, its mechanism of action in hepatocellular carcinoma in vivo has not been investigated in detail. We have previously shown that during hepatocellular carcinogenesis, DHEA treatment decreases formation of preneoplastic glutathione S-transferase placental form-positive foci in the liver and has antioxidant effects. Here we aimed to determine the mechanism of actions of DHEA, in comparison to vitamin E, in a chemically-induced hepatocellular carcinoma model in rats. Sprague-Dawley rats were administered with control diet without a carcinogen, diets with 1.5% vitamin E, 0.5% DHEA and both of the compounds with a carcinogen for 6 weeks. The doses were previously reported to have anti-cancer effects in animals without known toxicities. With DHEA treatment, cytosolic malate dehydrogenase activities were significantly increased by ~5 fold and glucose 6-phosphate dehydrogenase activities were decreased by ~25% compared to carcinogen treated group. Activities of Se-glutathione peroxidase in the cytotol was decreased significantly with DHEA treatment, confirming its antioxidative effect. However, liver microsomal cytochrome P-450 content and NADPH-dependent cytochrome P-450 reductase activities were not altered with DHEA treatment. Vitamin E treatment decreased cytosolic Se-glutathione peroxidase activities in accordance with our previous reports. However, vitamin E did not alter glucose 6-phosphate dehydrogenase or malate dehydrogenase activities. Our results suggest that DHEA may have decreased tumor nodule formation and reduced lipid peroxidation as previously reported, possibly by increasing the production of NADPH, a reducing equivalent for NADPH-dependent antioxidant enzymes. DHEA treatment tended to reduce glucose 6-phosphate dehydrogenase activities, which may have resulted in limited supply for de novo synthesis of DNA via inhibiting the hexose monophophaste pathway. Although both DHEA and vitamin E effectively reduced preneoplastic foci in this model, they seemed to function in different mechanisms. In conclusion, DHEA may be used to reduce hepatocellular carcinoma growth by targeting NADPH synthesis, cell proliferation and anti-oxidant enzyme activities during tumor growth.

Superparamagnetic iron oxide nanoparticles stabilized by alginate: Pharmacokinetics, tissue distribution, and applications in detecting liver cancers

The objectives of this study were to describe the pharmacokinetics and tissue distribution of superparamagnetic iron oxide nanoparticle (SPIO) stabilized with alginate (SPIO-alginate), and investigate its potential in detecting liver cancers as a newly developed magnetic resonance (MR) contrast agent. Pharmacokinetics and tissue distribution of SPIO-alginate were investigated in Sprague–Dawley rats. The results showed that SPIO-alginate was eliminated rapidly from serum with the half-life of 0.27 h at 109.5 μmol Fe/kg and accumulated dominantly in liver and spleen with a total percentage of more than 90% of dose after intravenous injection. The studies of pharmacokinetics and distribution of SPIO-alginate in rats indicated the MR contrast agent, based on SPIO, mainly accumulating in targeting organs that contain phagocytosing cells, i.e. liver and spleen. The efficacies in detecting hepatocellular carcinoma (HCC) of rat with primary liver cancer and xenograft liver cancers of rabbit were investigated before and after injection of SPIO-alginate. The signal intensity of liver parenchyma in rabbit with VX2 tumor after injection of SPIO-alginate was reduced sharply resulting in a significant contrast between liver parenchyma and tumor. Detection of the HCC in rat model was also demonstrated. The present study provides evidence that SPIO-alginate might have the ability to improve the detection of liver tumors as an MR contrast agent, and the efficacy is associated with the SPIO specifically located in Kupffer cells in hepatic sinusoid.

Multipotent Adult Progenitor Cells (MAPC) contribute to hepatocarcinoma neovasculature

The use of stem cells as a vehicle of therapeutic genes is an attractive approach for the development of new antitumoral strategies based on gene therapy. The aim of our study was to assess the potential of bone marrow-derived Multipotent Adult Progenitor Cells (rMAPCs) to differentiate in vitro and in vivo into endothelial cells and to be recruited to areas of tumor vasculogenesis. In vitro, rMAPCs obtained from Buffalo rats differentiated into cells expressing endothelial markers and demonstrated functional endothelial capacity. Intravenous injection of undifferentiated rMAPC transduced with a lentivirus expressing GFP in an orthotopic rat model of hepatocellular carcinoma, resulted in tumor recruitment of the injected cells and in vivo differentiation into endothelial cells in the tumor area with contribution to vasculogenesis. In summary, our results suggest that rMAPCs can be efficiently recruited by vascularized tumors and differentiate to endothelium and thus may represent a useful vehicle for delivery of therapeutic genes to sites of active tumor neovascularization.

Over-expression of the A3 adenosine receptor in tumor and PBMC of hepatocellular carcinoma patients: A specific therapeutic target

14085 Background: The Gi protein associated A3 adenosine receptor (A3AR) is highly expressed in colon carcinoma tissue and is reflected in peripheral blood mononuclear cells (PBMC) of the patients. Drug candidates with high affinity to the receptor possess anti-cancer effect when administered orally to colon carcinoma bearing animals. The receptor was suggested as a potent therapeutic target and predictive biological marker. Since there is no adequate therapy for Hepatocellular Carcinoma (HCC) we looked at the presence of A3AR in tumor and PBMC of HCC patients and tested the efficacy of the A3AR agonist, CF102 in an experimental rat HCC model. Methods: mRNA and protein A3AR expression level were examined in paraffin embedded slides and PBMC from HCC patients utilizing RT-PCR and Western blot (WB) analysis, respectively. Rat HCC model was established by inoculating N1S1 cells to the animals’ liver. Oral treatment with CF102 was initiated 5 days after tumor inoculation. Signaling proteins in tumor lesions and PBMC from the animals was tested by WB analysis. Results: A3AR over-expression was found in tumor and PBMC of HCC patients. Receptor over-expression was attributed to high expression of NF-κB, known to act as a transcription factor of A3AR. In the HCC bearing rats, A3AR was over-expressed in the tumor tissue and PBMC. Upon treatment with CF102 A3AR expression was down-regulated followed by inhibition of tumor size (60%±18.4%, p&lt;0.05). Mechanistically, CF102 de-regulated the NF-κB and Wnt signaling pathways. Conclusions: A3AR which is up- regulated in HCC tumors may be suggested as a new target to treat this malignancy and as a biological marker to follow up tumor response to the drug. No significant financial relationships to disclose.

Rho-Associated Kinase Inhibitor Reduces Tumor Recurrence After Liver Transplantation in a Rat Hepatoma Model

Tumor recurrence after liver transplantation still remains a significant problem in patients with hepatocellular carcinoma. The small GTPase Rho/Rho-associated kinase (ROCK) pathway is involved in the motility and invasiveness of cancer cells. We investigated whether tacrolimus activated the Rho/ROCK signal pathway to promote the invasiveness of rat hepatocellular carcinoma cells. We also investigated whether the ROCK inhibitor Y-27632 suppressed tumor recurrence after experimental liver transplantation in a rat hepatocellular carcinoma model. Orthotopic liver transplantation was performed in hepatocellular carcinoma cell line McA-RH7777-bearing rats. Tacrolimus was administered to liver transplant rats and these rats were divided into two groups: the Y-27632-treated (10 mg/kg, for 28 days) group and the Y-27632-untreated group. Tacrolimus enhanced the cancer cell migration and stimulated phosphorylation of the myosin light chain (MLC), a downstream effector of Rho/ROCK signaling. Y-27632 suppressed the cancer cell migration and tacrolimus-induced MLC phosphorylation. Suppression of tumor recurrence after liver transplantation and significant prolongation of survival were observed in the Y-27632-treated rats in comparison with theY-27632-untreated rats. Tacrolimus stimulates the Rho/ROCK signal pathway to enhance the invasiveness of hepatocellular carcinoma, and the ROCK inhibitor Y-27632 can be used as a new antimetastatic agent for the prevention of tumor recurrence after liver transplantation.

Sodium Iodide Symporter Is Expressed at the Preneoplastic Stages of Liver Carcinogenesis and in Human Cholangiocarcinoma

The ability of thyroid cells to take up iodide, which enables (131)I radiotherapy for thyroid cancer, is due to the expression of the sodium iodide symporter at their plasma membrane. Expression of this symporter has been found in some nonthyroid cancers. However, it is mostly accumulated in the cytoplasm, and its functionality has not been demonstrated. We have investigated sodium iodide symporter expression and functionality in human liver cancer, and in a diethylnitrosamine induced Wistar rat model of primary liver cancer at different stages of carcinogenesis. Sodium iodide symporter mRNA and protein were studied in tissues from patients with hepatocellular- or cholangio-carcinomas using reverse-transcription polymerase chain reaction, immunoblot, and immunohistochemistry. We studied the dynamics of hepatic iodine uptake in the animal model using nuclear imaging. Sodium iodide symporter expression showed up in all 20 cholangiocarcinomas, but in only 2 of the 26 hepatocellular carcinomas, investigated. It was also found in normal bile duct cells and in the ductular reaction present in cirrhotic tissues. It was located at the plasma membrane in 10 of 20 cholangiocarcinoma. In rat liver cancer, a functional sodium iodide symporter expression was triggered as from the early preneoplastic steps, and was amplified during clonal tumor cell expansion, allowing complete tumor suppression after (131)I radiotherapy. A significant proportion of human cholangiocarcinomas expresses membrane sodium iodide symporter, which may permit radioiodine therapy. Our data also suggest that (131)I acts on a crucial target for liver cancer development.