Hepatic Tumor Cells Research Articles

Over-expression of VEGF and MMP-9 in residual tumor cells of hepatocellular carcinoma after embolization with lipidol

The expression and implication of vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9) in residual hepatic tumor cells after lipiodol embolization were investigated. Two weeks after transplantation of VX2 tumor cells into the livers of rabbits, a xenograft model of the human hepatic neoplasm was successfully established. Forty rabbits were randomly divided into control group (n=20) and lipiodol group (n=20). For the control group, 1 mL normal saline was injected through the gastroduodenal artery, whereas 0.3 mL/kg lipiodol was applied for the lipiodol group. One week after embolization, the expression level of VEGF in the plasma was measured by using enzyme-linked immunosorbent assay (ELISA). A three-step immunohistochemical technique (ABC) was employed to detect the protein levels of VEGF and MMP-9 and the quantitative PCR for their mRNA levels was performed in the residual tumor cells. The VEGF in the plasma was significantly higher in the lipiodol group (1.42±0.29 ng/mL) than in the control group (1.12±0.21 ng/mL) (P<0.01). Moreover, the positive rate of VEGF protein in the residual tumor cells was significantly higher in the lipiodol group (62.13%±7.69%) than in the control group (53.16%±9.17%) (P<0.05). Similarly, the MMP-9 expression in the residual tumor cells was higher in the lipiodol group. The mRNA levels of VEGF (2.9313±2.4231) and MMP-9 (3.5721±1.6107) in the lipiodol group were significantly higher than those in the control group (1.5728±0.9453 and 1.7573±1.0641, respectively, P<0.05). Therefore, it was reasonable to speculate that the increased expression of VEGF and MMP-9 in residual hepatic tumor cells and tumor angiogenesis post-embolization would be responsible for the increased metastatic potentiality and invasiveness of these cells.

Targeting EpCAM (CD326) for immunotherapy in hepatoblastoma

Hepatoblastoma (HB) is the most common liver cancer in children. Recurrence of HB after chemotherapy and surgery is frequent among high-risk patients and is associated with chemoresistance. Immunotherapy may improve poor treatment outcomes in HB patients. Cytotoxic leukocytes of the innate and adaptive immune system including different populations of cytotoxic T cells play a major role in fighting developing tumors. In this setting, monoclonal antibodies may be employed to specifically direct immune responses toward tumor cells. We addressed this issue by using humanized antibodies that recognize the cell surface molecule EpCAM (CD326, overexpressed in hepatic tumor cells) to enhance immune responses against HB. EpCAM was constantly expressed on HB cells and its expression was independent of previous therapy based on the DNA-damaging agent cisplatin. Co-culture assays performed with two well-described HB cell lines and tumor tissue cultures demonstrated that tumor cell lysis by γδ T cells can be dramatically augmented by applying EpCAM-specific monoclonal antibodies. These data emphasize the value of antitumor immune responses and encourage adapting immunotherapeutic regimens to improve the outcome of high risk HB.

In vivoassessment of intratumoral aspirin injection to treat hepatic tumors

To study the antineoplastic efficacy of 10% aspirin intralesional injection on VX2 hepatic tumors in a rabbit model. Thirty-two male rabbits (age: 6-9 wk; body weight: 1700-2500 g) were inoculated with VX2 hepatic tumor cells (10(4) cells/rabbit) via supra-umbilical median laparotomy. On day 4 post-implantation, when the tumors were about 1 cm in diameter, the rabbits were randomly divided into the following groups (n = 8 each group) to assess early (24 h) and late (7 d) antineoplastic effects of intratumoral injection of 10% bicarbonate aspirin solution (experimental groups) in comparison to intratumoral injection of physiological saline solution (control groups): group 1, 24 h control; group 2, 24 h experimental; group 3, 7 d control; group 4, 7 d experimental. The serum biochemistry profile (measurements of glycemia, alkaline phosphatase, gamma-glutamyl transferase, aspartate aminotransferase, and alanine aminotransferase) and body weight measurements were obtained for all animals at the following time points: D0, before tumor implant; D4, day of treatment; D5, day of sacrifice for groups 1 and 2; D11, day of sacrifice for groups 3 and 4. Gross assessments of the abdominal and thoracic cavities were carried out upon sacrifice. The resected liver tissues, including hepatic tumors, were qualitatively (general morphology, signs of necrosis) and quantitatively (tumor area) assessed by histopathological analysis. Gross examination showed no alterations, besides the left hepatic lobe tumors, had occurred in the thoracic and abdominal cavities of any animal at any time point evaluated. However, the features of the tumor foci were distinctive between the groups. Compared to the control groups, which showed normal unabated tumor progression, the aspirin-treated groups showed imprecise but limited tumor boundaries and a general red-white coloration (indicating hemorrhaging) at 24 h post-treatment, and development of yellow-white areas of a cicatricial aspect at 7 d after treatment. At all time points evaluated, all except one biochemical parameters tested within the reference range (P > 0.05); a significant increase was detected in the alkaline phosphatase level of the control group 3 on D11 (P < 0.05). At 24 h post-treatment, the aspirin-treated groups showed extensive coagulation necrosis accompanied by a remarkable absence of viable tumor foci; at 7 d after treatment, the tumors had completely disappeared in these animals and fibrous necrotic nodules had developed. In contrast, throughout the study course, the tumors of the control groups remained unchanged, showing tumor nodules without necrosis at the time point corresponding to 24 h post-treatment and increased amounts of tumor nodules at the time point corresponding to 7 d post-treatment. Quantitative analysis of the remaining tumor area revealed that the aspirin-treated groups had significantly smaller tumor foci at 24 h post-treatment (8.5% ± 0.7%) and at 7 d after treatment (11.0% ± 4.2%), compared to those in the control groups (24 h: 98.5% ± 1.5% and 7 d: 94.0% ± 2.7%; both, P < 0.005). Intralesional injection of a 10% aspirin solution causes destruction of VX2 hepatic tumors in rabbits without evidence of relapse at 7 d after treatment administration.

The activity of γδ T cells against paediatric liver tumour cells and spheroids in cell culture

Chemoresistance and advanced tumour stage at time of diagnosis are the major reasons for poor treatment results in hepatoblastoma (HB) and paediatric hepatocellular carcinoma (HCC). Positive results with transplantation of liver and bone marrow revealed the impact of the immune system on the treatment of liver malignancies. Cytotoxic-immune-cells-like natural killer (NK) and T cells are major player in the defence against developing tumours. This study aimed to specifically analyse the ability of ex-vivo expanded γδ T cells to recognise and lyse HB and HCC cell lines in coculture assays. Cell viability after treatment with γδ T cells was evaluated with two HB (HUH6 and HepT1) and one HCC cell line (HC-AFW1) using a MTT-based cytotoxicity assay. The binding of T cells to target cells was monitored using immunofluorescence microscopy. Incubation of hepatic tumour cell lines with γδ T cells led to a significant decrease in tumour cell viability. This was enhanced by zoledronic acid and histone deacetylase inhibitors. MT110, an EpCAM/CD3-bispecific BiTE antibody could bluntly enhance tumour cell lysis close to completion. γδ T cells efficiently interacted with HB and HCC cells in a spheroid culture model. Bispecific antibodies such as MT110 might be used to intensify the antitumoural effect of γδ T cells in context of adoptive immune cell transfer. Optimised immunotherapeutic strategies might therefore improve the outcome of high risk hepatoblastoma and hepatocellular carcinoma.

ChemInform Abstract: Heterocycles. Part 27. Microwave‐Assisted Synthesis and Antitumor Activity of Novel Phenothiazinyl‐Thiazolyl‐Hydrazine Derivatives.

AbstractMicrowave‐assisted Hantzsch cyclization leads to novel phenothiazinyl‐thiazolyl‐hydrazine derivatives (III) which are evaluated for their antiproliferative effect against hepatic HepG2 tumor cells and colon carcinoma CC531S cells.

Suppression of inflammation by tumor-derived exosomes: a kind of natural liposome packaged with multifunctional proteins

Exosomes are small-membrane vesicles secreted by hematopoietic and malignant epithelial cells as well as trophoblasts. The composition of cancerous exosomes has been proven to play pivotal roles in the maintenance of the microenvironment that is beneficial for the progression of cancer, such as Fas-ligand–triggered lymphocyte apoptosis. We supposed that the immunosuppressive effect of cancerous exosomes might be helpful in the treatment of diseases characterized by overactivation of the immune system and subsequent tissue injury. The aim of this study was to evaluate the protective effect of tumor-derived exosomes in the mice model of lipopolysaccharide (LPS)-induced inflammation. Tetrazolium (MTT) and DNA electrophoresis were used to measure the cytotoxicity of exosomes on lymphocytes. Pathologic observation of tissue sections, serologic analysis of aspartate aminotransferase/alanine aminotransferase (AST/ALT), and urinary analysis of protein were used to assess the protection effect of exosomes in LPS-induced multiorgan damage. In vitro outcomes of MTT and DNA electrophoresis showed the cytotoxicity of exosomes on lymphocytes. Together with the alleviation of organ damages evaluated by urine protein, serum AST/ALT, and pathologic analysis, we confirmed the possibility that pretreatment of mice with exosomes, produced by H22 hepatic tumor cells, resulted in protection against LPS-induced tissue damage, which is caused by overactivation of the immune system and inflammation response. This therapeutic strategy will raise an interesting way to search new therapeutics in pairs of diseases with complementarities in etiology and pathology, namely, a strategy of taking advantage of the mutual complementarities between diseases.

Differential effects of arsenic trioxide on chemosensitization in human hepatic tumor and stellate cell lines

BackgroundCrosstalk between malignant hepatocytes and the surrounding peritumoral stroma is a key modulator of hepatocarcinogenesis and therapeutic resistance. To examine the chemotherapy resistance of these two cellular compartments in vitro, we evaluated a well-established hepatic tumor cell line, HepG2, and an adult hepatic stellate cell line, LX2. The aim was to compare the chemosensitization potential of arsenic trioxide (ATO) in combination with sorafenib or fluorouracil (5-FU), in both hepatic tumor cells and stromal cells.MethodsCytotoxicity of ATO, 5-FU, and sorafenib, alone and in combination against HepG2 cells and LX2 cells was measured by an automated high throughput cell-based proliferation assay. Changes in survival and apoptotic signaling pathways were analyzed by flow cytometry and western blot. Gene expression of the 5-FU metabolic enzyme, thymidylate synthase, was analyzed by real time PCR.ResultsBoth HepG2 and LX2 cell lines were susceptible to single agent sorafenib and ATO at 24 hr (ATO IC50: 5.3 μM in LX2; 32.7 μM in HepG2; Sorafenib IC50: 11.8 μM in LX2; 9.9 μM in HepG2). In contrast, 5-FU cytotoxicity required higher concentrations and prolonged (48–72 hr) drug exposure. Concurrent ATO and 5-FU treatment of HepG2 cells was synergistic, leading to increased cytotoxicity due in part to modulation of thymidylate synthase levels by ATO. Concurrent ATO and sorafenib treatment showed a trend towards increased HepG2 cytotoxicity, possibly due to a significant decrease in MAPK activation in comparison to treatment with ATO alone.ConclusionsATO differentially sensitizes hepatic tumor cells and adult hepatic stellate cells to 5-FU and sorafenib. Given the importance of both of these cell types in hepatocarcinogenesis, these data have implications for the rational development of anti-cancer therapy combinations for the treatment of hepatocellular carcinoma (HCC).

Increased Expression of Epithelial Cell Adhesion Molecule (EpCAM) in Rat Hepatic Tumors Induced by Diethylnitrosamine

The epithelial cell adhesion molecule (EpCAM) is a pan-epithelial differentiation antigen that is expressed on almost all carcinomas. However, a role in rat liver carcinogenesis has never been reported previously. Thus, its expression was investigated herein in rat liver tumors induced by diethylnitrosamine (DEN). Twenty male 5-week-old F344 rats were used in this experiment. Mini-osmotic pumps containing doses of 47.5 mg of DEN were inserted into the abdominal cavity of each animal to initiate liver carcinogenesis. All animals were sacrificed at 26 weeks after DEN treatment. At necropsy, hepatic masses were processed for histopathological examination, which revealed forty-four hepatocellular adenomas (HCAs) and twenty hepatocellular carcinomas (HCC). Tumors were immunohistochemically analyzed for EpCAM, proliferating cell nuclear antigen (PCNA) and co-localization of the two. EpCAM expression was mainly detected in hepatic tumor cells, showing a cytoplasmic staining pattern. However, expression was also slightly observed in normally-appearing surrounding hepatic cells. PCNA expression was highly detected in tumor cells, showing nuclear staining. Double staining of EpCAM and PCNA in tumors showed many cells with co- localization. Taken together, EpCAM and PCNA expression were increased in DEN-induced tumors and many tumor cells showed co-expression. It is suggested that EpCAM may increase during DEN-induced tumors, possibly associated with cell proliferation.

Formation and cytotoxicity of a new disinfection by-product (DBP) phenazine by chloramination of water containing diphenylamine

Disinfection by-products (DBPs) in drinking water have caused worldwide concern due to their potential carcinogenic effects. The formation of phenazine from diphenylamine (DPhA) chloramination was studied and its cytotoxicities for two human cancer cells were also investigated. Phenazine was detected synchronously with the consumption of DPhA by chloramination, which further confirmed that the new DBP phenazine can be produced along with N-nitrosodiphenylamine (NDPhA) from DPhA chloramination. The formation of phenazine had a maximum molar yield with solution pH increasing from 5.0 to 9.0, with phenazine as the main product for DPhA chloramination at lower pH, but higher pH favored the formation of NDPhA. Thus, solution pH is the key factor in controlling the formation of phenazine and NDPhA. Both the initial DPhA and chloramine concentrations did not show a significant effect on the molar yields of phenazine, although increasing the chloramine concentration could speed up the reaction rate of DPhA with chloramines. The cytotoxicity assays showed that phenazine had significant cell-specific toxicity towards T24 (bladder cancer cell lines) and HepG2 (hepatic tumor cell lines) cells with IC50 values of 0.50 and 2.04 mmol/L, respectively, and T24 cells being more sensitive to phenazine than HepG2 cells. The IC50 values of phenazine, DPhA, and NDPhA for T24 cells were of the same order of magnitude and the cytotoxicity of phenazine for T24 cells was slightly lower than that of NDPhA (IC50, 0.16 mmol/L), suggesting that phenazine in drinking water may have an adverse effect on human health.

A flavonoid component from Docynia delavayi (Franch.) Schneid represses transplanted H22 hepatoma growth and exhibits low toxic effect on tumor-bearing mice

The fruit of Docynia delavayi (Franch.) Schneid is a kind of popular food in southwestern areas of China. Additionally, its rhizome has been long used as a folk medicine in the treatment of liver cancer by local people. Chrysin is a kind of flavonoid which induces cancer cell death in vitro. However, its anti-tumor activity in vivo and toxicological effects on the tumor-bearing animals still remain poorly understood. In this study, we obtained four flavonoids from this herb. Among them, chrysin showed the strongest cytotoxic effect on an array of cultured tumor cells. Further investigations revealed that it significantly repressed transplanted H22 ascitic hepatic tumor cell growth in vivo. Moreover, this compound displayed little toxic effects. Additionally, we demonstrated that in transplanted tumor tissues, chrysin not only activated caspase-3 and induced apoptosis, but also inhibited the production of vascular endothelial growth factor (VEGF) and suppressed angiogenesis. These data showed that chrysin exhibited prominent anti-tumor activities and low toxic effects in vivo.

Efficient Enrichment of Hepatic Cancer Stem-Like Cells from a Primary Rat HCC Model via a Density Gradient Centrifugation-Centered Method

BackgroundBecause few definitive markers are available for hepatic cancer stem cells (HCSCs), based on physical rather than immunochemical properties, we applied a novel method to enrich HCSCs.MethodologyAfter hepatic tumor cells (HTCs) were first isolated from diethylinitrosamine-induced F344 rat HCC model using percoll discontinuous gradient centrifugation (PDGC) and purified via differential trypsinization and differential attachment (DTDA), they were separated into four fractions using percoll continuous gradient centrifugation (PCGC) and sequentially designated as fractions I–IV (FI–IV). Morphological characteristics, mRNA and protein levels of stem cell markers, proliferative abilities, induced differentiation, in vitro migratory capacities, in vitro chemo-resistant capacities, and in vivo malignant capacities were determined for the cells of each fraction.FindingsAs the density of cells increased, 22.18%, 11.62%, 4.73% and 61.47% of primary cultured HTCs were segregated in FI–FIV, respectively. The cells from FIII (density between 1.041 and 1.062 g/ml) displayed a higher nuclear-cytoplasmic ratio and fewer organelles and expressed higher levels of stem cell markers (AFP, EpCAM and CD133) than cells from other fractions (P<0.01). Additionally, in vitro, the cells from FIII showed a greater capacity to self-renew, differentiate into mature HTCs, transit across membranes, close scratches, and carry resistance to chemotherapy than did cells from any other fraction; in vivo, injection of only 1×104 cells from FIII could generate tumors not only in subcutaneous tissue but also in the livers of nude mice.ConclusionsThrough our novel method, HCSC-like cells were successfully enriched in FIII. This study will greatly contribute to two important areas of biological interest: CSC isolation and HCC therapy.

Heterocycles 27. Microwave Assisted Synthesis and Antitumour Activity of Novel Phenothiazinyl‐Thiazolyl‐Hydrazine Derivatives

A series of new phenothiazinyl-thiazolyl-hydrazine derivatives were synthesized by Hantzsch cyclization of 1-(10-ethyl-10H-phenothiazin-3-yl)-methylidene-thiosemicarbazide with α-halocarbonyl derivatives. Comparison between classical and microwave assisted synthesis emphasizes the great advantages induced by microwaves irradiation which afforded high reaction yields in much shorter reaction time. Structural assignments were based on spectroscopic methods (high resolution NMR, FTIR, MS). The new compounds were tested in vitro for their antiproliferative activity against tumor cell lines using spectrometric methods. Most of the compounds exhibit cytotoxicity against hepatic and colon tumor cells in a dose-dependent mode and a relationship between the structure and their biological activity was observed.

Branch chain amino acid, insulin, and hepatic tumor cell proliferation

Branch chain amino acid, insulin, and hepatic tumor cell proliferation

Branched‐chain amino acids prevent insulin‐induced hepatic tumor cell proliferation by inducing apoptosis through mTORC1 and mTORC2‐dependent mechanisms

Branched-chain amino acids (BCAA) supplementation has been reported to suppress the incidence of liver cancer in obese patients with liver cirrhosis or in obese and diabetic model animals of carcinogenesis. Whether BCAA directly suppresses cell proliferation of hepatic tumor cells under hyperinsulinemic condition remain to be defined. The aim of this study was to investigate the effects of BCAA on insulin-induced proliferation of hepatic tumor cells and determine the underlying mechanisms. BCAA suppressed insulin-induced cell proliferation of H4IIE, HepG2 cells. In H4IIE cells, BCAA did not affect cell cycle progression but increased apoptosis by suppressing expressions of anti-apoptotic genes and inducing pro-apoptotic gene via inactivation of PI3K/Akt and NF-κB signaling pathways. Further studies demonstrated that BCAA inhibited PI3K/Akt pathway not only by promoting negative feedback loop from mammalian target of rapamycin complex 1 (mTORC1)/S6K1 to PI3K/Akt pathway, but also by suppressing mTORC2 kinase activity toward Akt. Our findings suggest that BCAA supplementation may be useful to suppress liver cancer progression by inhibiting insulin-induced PI3K/Akt and subsequent anti-apoptotic pathway, indicating the importance of BCAA supplementation to the obese patients with advanced liver disease.

The analysis of organic anion transporting polypeptide (OATP) mRNA and protein patterns in primary and metastatic liver cancer

Organic anion transporting polypeptides (OATP, SLCO genes) mediate the uptake of endobiotics and drugs. Thus, their expression levels and pattern could be of relevance for cancer therapy. This prompted us to investigate the expression of poorly characterized OATPs, namely OATP2A1, OATP3A1, OATP4A1 and OATP5A1 in hepatic cancer of different origin. First, mRNA levels of all eleven OATPs were determined in paired (cancerous and adjacent non-cancerous) specimens from 43 patients with primary liver cancer (hepatocellular carcinoma, HCC; cholangiocellular carcinoma, CCC) and liver metastases from colon tumors (MLT). Real-time RT-PCR analysis revealed that all OATPs, except OATP1C1 and OATP6A1, are extensively expressed in nearly all samples. In contrast to downregulated OATP1B1, OATP1B3, OATP1A2 and OATP2B1 in cancerous vs. non-cancerous samples, an increase in OATP2A1, OATP3A1, OATP4A1 and OATP5A1 mRNA levels was seen in tumors (up to 40-fold for OATP5A1 in the MLT group). Therefore, OATP2A1, OATP3A1, OATP4A1 and OATP5A1 were further investigated by immunofluorescence microscopy on paraffin-embedded cancerous and non-cancerous sections (seven per group). OATP-derived immunoreactivity was observed in plasma membranes and cytosol of hepatic tumor cells, and additionally, in various cytokeratin 19 positive bile ducts. An increased percentage of immunoreactive cells and a higher staining intensity in cancerous vs. non-cancerous paraffin sections paralleled higher mRNA levels of OATP2A1, OATP3A1, OATP4A1 and OATP5A1 in cancerous tissues of HCC, CCC and MLT patients. The extensive expression of OATP2A1, OATP3A1, OATP4A1 and OATP5A1 in hepatic tumors of different origin suggests that these transporters might be further exploited for the discovery of novel anticancer agents.

Liver fibrogenic cells

Liver fibrogenic cells are a heterogenous population of cells that include α-smooth muscle actin positive myofibroblasts (MFs). MFs promote the progression of chronic liver diseases (CLDs) towards cirrhosis. MFs are highly proliferative and contractile and promote fibrogenesis by means of their multiple phenotypic responses to injury. These include: excess deposition and altered remodelling of extracellular matrix; the synthesis and release of growth factor which sustain and perpetuate fibrogenesis; chronic inflammatory response and neo-angiogenesis. MFs mainly originate from hepatic stellate cells or portal fibroblasts through activation and transdifferentiation. MFs may also potentially differentiate from bone marrow-derived stem cells. It has been suggested that MFs can be derived from hepatocytes or cholangiocytes through a process of epithelial to mesenchymal transition in the liver, however this is controversial. Hepatic MFs may also modulate the immune responses to hepatocellular carcinomas and metastatic cancers through cross talk with hepatic progenitor and tumour cells.

Alterations in hepatic tumor cell colonization during obesity

Alterations in hepatic tumor cell colonization during obesity

Generation of a panel of monoclonal antibodies against atypical chemokine receptor CCX-CKR by DNA immunization

Introduction Chemokines are regulated by a family of ‘atypical’ chemokine receptors, D6, DARC and CCX-CKR, each of which efficiently internalizes its cognate chemokine ligands. Development of monoclonal antibodies (MAbs) that would recognize CCX-CKR on the cell surface will be helpful to identify primary CCX-CKR-expressing cell types and analyze the fate of CCX-CKR after ligand binding to the receptor. Methods We generated IgG MAbs recognizing the cell-surface CCX-CKR by DNA immunization using a molecular adjuvant, and analyzed the epitope recognized by the MAbs. Then, the reactivities of the MAbs with CCX-CKR-transfected cells, and also hepatocytes and hepatic tumor lines were evaluated. Finally, we also tested the ligand-like activities of the MAbs, namely, induction of internalization of CCX-CKR by the MAbs. Results A panel of MAbs reacting with CCX-CKR expressed on the cell surface was prepared. The panel was a small one, consisting of only ten MAbs, but was rich in terms of diversity of the Ig isotypes and of the epitopes. Epitope analyses revealed that all the 10 MAbs recognized at least three different, although very close, peptide structures of the N-terminal domain. Three MAbs, namely, 2F11, 13E11 and 14F10, were selected to represent the panel. All of the MAbs were applicable for flow cytometry and immunoflurescent assays and immunoprecipitation. The reactivity of the 2F11 MAb was also confirmed by western blotting. Endogenous expression of CCX-CKR on human hepatocytes and hepatic tumor cell lines was demonstrated using the 13E11 MAb. Interestingly, binding of the 13E11 MAb with B300-19 cells expressing CCX-CKR resulted in induction of CCX-CKR internalization. Discussion This panel of MAbs may be expected to prove valuable for further study of the functions of this silent chemokine receptor, including those related to the homeostasis of lymphoid cells, and to the growth and metastasis of hepatic cancer.

Direct Recruitment of Insulin Receptor and ERK Signaling Cascade to Insulin-Inducible Gene Loci

OBJECTIVEInsulin receptor (IR) translocates to the nucleus, but its recruitment to gene loci has not been demonstrated. Here, we tested the hypothesis that IR and its downstream mitogenic transducers are corecruited to two prototypic insulin-inducible genes: early growth response 1 (egr-1), involved in mitogenic response, and glucokinase (Gck), encoding a key metabolic enzyme.RESEARCH DESIGN AND METHODSWe used RNA and chromatin from insulin-treated rat hepatic tumor cell line expressing human insulin receptor (HTC-IR) and livers from lean and insulin-resistant ob/ob glucose-fed mice in quantitative RT-PCR and chromatin immunoprecipitation studies to determine gene expression levels and associated recruitment of RNA polymerase II (Pol II), insulin receptor, and cognate signaling proteins to gene loci, respectively.RESULTSInsulin-induced egr-1 mRNA in HTC-IR cells was associated with corecruitment of IR signaling cascade (IR, SOS, Grb2, B-Raf, MEK, and ERK) to this gene. Recruitment profiles of phosphorylated IR, B-Raf, MEK, and Erk along egr-1 transcribed region were similar to those of elongating Pol II. Glucose-feeding increased Gck mRNA expression in livers of lean but not ob/ob mice. In lean mice, there was glucose feeding-induced recruitment of IR and its transducers to Gck gene synchronized with elongating Pol II. In sharp contrast, in glucose-fed ob/ob mice, the Gck recruitment patterns of active MEK/Erk, IR, and Pol II were asynchronous.CONCLUSIONSIR and its signal transducers recruited to genes coupled to elongating Pol II may play a role in maintaining productive mRNA synthesis of target genes. These studies suggest a possibility that impaired Pol II processivity along genes bearing aberrant levels of IR/signal transducers is a previously unrecognized facet of insulin resistance.

Salirasib inhibits the growth of hepatocarcinoma cell lines in vitro and tumor growth in vivo through ras and mTOR inhibition

BackgroundDysregulation of epidermal growth factor and insulin-like growth factor signaling play important roles in human hepatocellular carcinoma (HCC), leading to frequent activation of their downstream targets, the ras/raf/extracellular signal-regulated kinase (ERK) and the phosphoinositide 3-kinase (PI3K)/Akt/mammalian Target of Rapamycin (mTOR) pathways. Salirasib is an S-prenyl-cysteine analog that has been shown to block ras and/or mTOR activation in several non hepatic tumor cell lines. We investigated in vitro the effect of salirasib on cell growth as well as its mechanism of action in human hepatoma cell lines (HepG2, Huh7, and Hep3B) and its in vivo effect in a subcutaneous xenograft model with HepG2 cells.ResultsSalirasib induced a time and dose dependent growth inhibition in hepatocarcinoma cells through inhibition of proliferation and partially through induction of apoptosis. A 50 percent reduction in cell growth was obtained in all three cell lines at a dose of 150 μM when they were cultured with serum. By contrast, salirasib was more potent at reducing cell growth after stimulation with EGF or IGF2 under serum-free conditions, with an IC50 ranging from 60 μM to 85 μM. The drug-induced anti-proliferative effect was associated with downregulation of cyclin A and to a lesser extent of cyclin D1, and upregulation of p21 and p27. Apoptosis induction was related to a global pro-apoptotic balance with caspase 3 activation, cytochrome c release, death receptor upregulation, and a reduced mRNA expression of the apoptosis inhibitors cFLIP and survivin. These effects were associated with ras downregulation and mTOR inhibition, without reduction of ERK and Akt activation. In vivo, salirasib reduced tumour growth from day 5 onwards. After 12 days of treatment, mean tumor weight was diminished by 56 percent in the treated animals.ConclusionsOur results show for the first time that salirasib inhibits the growth of human hepatoma cell lines through inhibition of proliferation and induction of apoptosis, which is associated with ras and mTOR inhibition. The therapeutic potential of salirasib in human HCC was further confirmed in a subcutaneous xenograft model.