Human Hepatocellular Carcinoma Lines Research Articles

Perfusion culture of multi-layered HepG2 hepatocellular carcinoma cells in a pressure-driven microphysiological system

Here we report the perfusion culture of a multi-layered tissue composed of HepG2 cells (a human hepatoma line) in a pressure-driven microphysiological system (PD-MPS), which we developed previously as a multi-throughput perfusion culture platform. The perfusion culture of multi-layered tissue model was constructed by inserting a modified commercially available permeable membrane insert into the PD-MPS. HepG2 cells were layered on the membrane, and culture medium was perfused both through and below the membrane. The seeded density (number of cells/cm2) of the culture model is 70 times that of static culture in a conventional 35-mm culture dish. Pressure-driven circulation of the medium in our compact device (8.6× 7.0× 4.5cm3), which comprised two perfusion-culture modules and a pneumatic connection port, enabled perfusion culture of two multi-layered tissues (initially 1× 105cells). To obtain insight into the basic functionality of the multi-layered tissues as hepatocytes, we compared albumin production and urea synthesis between perfusion cultures and static cultures. The HepG2 cells grew and secreted increasing amounts of albumin throughout 20 days of perfusion culture, whereas albumin secretion did not increase under static culture conditions. In addition, on day 20, the amount of albumin secreted by the HepG2 cells in the microfluidic device was 68% of that in the conventional culture dish, which was seeded with the same number of cells but had a 70 times larger culture area. These features of high-density culture of functioning cells in a compact device support the application of PD-MPS in single- and multi-organ MPS.

DDX17 protects hepatocytes against oleic acid/palmitic acid-induced lipid accumulation

Hepatic lipid accumulation is an initiation factor in fatty liver disease, and promoting a reduction in hepatic lipid accumulation is an important treatment strategy. DEAD box RNA helicase 17 (DDX17) is a member of the DEAD-box family and a molecular chaperone. Previous studies have demonstrated that DDX17 is a transcriptional coregulator of tumorigenesis, inflammation, and macrophage cholesterol efflux. The liver is the main site for lipid metabolism, and metabolic (dysfunction)-associated fatty liver disease (MAFLD) is one of the most common chronic liver diseases. However, the impact of DDX17 on hepatic lipid accumulation has not been verified. In this study, we found, for the first time, that oleic acid/palmitic acid (OA/PA)-induced lipid accumulation was largely abrogated by DDX17 overexpression in both HepG2 (a human hepatocellular carcinoma line) and Hep1-6 (a murine hepatocellular carcinoma line) cells, and this effect was due to a marked reduction in cellular triglyceride (TG) content. Moreover, the overexpression of DDX17 was accompanied by a significant decrease in the expression of genes involved in de novo fatty acid synthesis (FAS, ACC, and SCD-1) in both HepG2 and Hep1-6 cells. In conclusion, DDX17 protected against OA/PA-induced lipid accumulation in hepatocytes through de novo lipogenesis inhibition.

RAB18 is a key regulator of GalNAc-conjugated siRNA-induced silencing in Hep3B cells

Small interfering RNA (siRNA) therapeutics have developed rapidly in recent years, despite the challenges associated with delivery of large, highly charged nucleic acids. Delivery of siRNA therapeutics to the liver has been established, with conjugation of siRNA to N-acetylgalactosamine (GalNAc) providing durable gene knockdown in hepatocytes following subcutaneous injection. GalNAc binds the asialoglycoprotein receptor (ASGPR) that is highly expressed on hepatocytes and exploits this scavenger receptor to deliver siRNA across the plasma membrane by endocytosis. However, siRNA needs to access the RNA-induced silencing complex (RISC) in the cytoplasm to provide effective gene knockdown, and the entire siRNA delivery process is very inefficient, likely because of steps required for endosomal escape, intracellular trafficking, and stability of siRNA. To reveal the cellular factors limiting delivery of siRNA therapeutics, we performed a genome-wide pooled knockout screen on the basis of delivery of GalNAc-conjugated siRNA targeting the HPRT1 gene in the human hepatocellular carcinoma line Hep3B. Our primary genome-wide pooled knockout screen identified candidate genes that when knocked out significantly enhanced siRNA efficacy in Hep3B cells. Follow-up studies indicate that knockout of RAB18 improved the efficacy of siRNA delivered by GalNAc, cholesterol, or antibodies, but not siRNA delivered by Lipofectamine transfection, suggesting a role for RAB18 in siRNA delivery and intracellular trafficking.

Molecularly targeted anti-cancer drugs inhibit the invasion and metastasis of hepatocellular carcinoma by regulating the expression of MMP and TIMP gene families

To investigate the effect of multi-kinase kinase inhibitors (sorafenib; regorafenib; lenvatinib) on the invasion and metastasis of human hepatocellular carcinoma (HCC) cells, and the outcome of this effect on the expression of matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs), yet unclarified. Cells were subjected to four different treatments: blank control group, sorafenib (10 μmol/L) treatment group, regorafenib (20 mmol/L) treatment group, and lenvatinib (4 μmol/L) treatment group. Anti-invasion and anti-metastasis effects were tested using the wound-healing assay and transwell invasion assay. Real-time PCR and Western blot analyses were used to determine the impact of sorafenib, regorafenib, and lenvatinib on the gene expression of MMPs and TIMPs in the two HCC lines (Hep3B and SMMC-7721). Results from the wound-healing and transwell invasion assays showed the three tested anti-cancer drugs to have a significant inhibitory effect on the metastasis and invasion of HCC cells. Real-time PCR and western blot analyses revealed that sorafenib down-regulated the expressions of MMP-7,10,16 and up-regulated those of TIMP-1,3,4, regorafenib down-regulated the expression of MMP-1 and up-regulated TIMP-3 gene expression, and lenvatinib down-regulated the expressions of MMP-1,2,7,9,10,16 and up-regulated those of TIMP-1,3,4. However, these three targeted anti-cancer drugs seem to have no significant regulatory effect on the expressions of other MMPs and TIMPs family genes. In conclusion, sorafenib, regorafenib, and lenvatinib inhibit the invasion and metastasis of HCC cells by regulating MMPs/TIMPs expression levels.

Effects of low-density lipoprotein docosahexaenoic acid nanoparticles on cancer stem cells isolated from human hepatoma cell lines.

Docosahexaenoic acid (DHA) is an omega-3 polyunsaturated fatty acid with anti-cancer properties. Recently, DHA packaged within low-density lipoprotein (LDL) nanoparticles (LDL-DHA) was demonstrated to be effective in a murine model of hepatocellular carcinoma (HCC). Cancer stem cells (CSCs) are a subpopulation of tumor cells that are resistant to most cancer therapies and thereby, contribute to tumor recurrences. To determine whether LDL-DHA is effective against CSCs derived from human HCC cell lines and tumor bearing rats. Epithelial cellular adhesion molecule positive and CD133 negative (EpCAM+CD133-) CSCs were isolated from HuH-7 and HepG2 human HCC lines and exposed to varying concentrations (1-60µM) of LDL-DHA nanoparticles for 0-72h. HCC tumor bearing rats were treated with 2mg/kg LDL-DHA nanoparticles for 3 days. Regardless of the cell line employed, LDL-DHA nanoparticles achieved 70-100% killing of EpCAM+CD133- CSCs at a concentration of 40µM after 48h of exposure while DHA and LDL alone had minimal or no cytotoxic effects. Similar results were obtained with LDL-DHA nanoparticle treatment of EpCAM-CD133- adult cancer cells (ACCs). In keeping with these findings were similar levels of low density lipoprotein receptor expression and LDL-DHA nanoparticle induced lipid peroxidation activity and reactive oxygen species in the CSC and ACC populations. However, differences in sensitivity to LDL-DHA treatment were observed in vivo experiments where LDL-DHA nanoparticle treated tumors had a higher percent of surviving CSCs relative to ACCs. Further research on LDL-DHA nanoparticle therapy for human HCC is warranted.

Downregulation of Raf-1 kinase inhibitory protein as a sorafenib resistance mechanism in hepatocellular carcinoma cell lines.

325 Background: Despite enhancing overall survival, sorafenib resistance usually occurs and is a significant limiting factor of improved prognosis in hepatocellular carcinoma (HCC) patients. Therefore, it is important to identify the mechanism of sorafenib resistance. This study is designed to identify that causative factor for sorafenib resistance and to suggest way for overcoming sorafenib resistance. Methods: The sensitivity of sorafenib was compared in human HCC lines and patient-derived HCC primary cells. Based on its cytotoxicity, analysis was performed to examine the altered signaling pathway by sorafenib and its causative factor. It was further investigated that how sorafenib modify the sorafenib resistant inducer through gene or protein expression or stability. We also design the treatment option to overcome sorafenib resistance. Results: Sorafenib activates the Raf/MEK/ERK pathway, causing sorafenib resistance in HCC cell lines and patient-derived HCC primary cells. Reactivation of the MAPK pathway by sorafenib occurs via down-regulation of RKIP at a post-translational level. Knockdown of RKIP increased phosphorylated ERK and consequently suppressed sorafenib-mediated cell death. We also found that sorafenib-reactivated ERK maybe an attractive target for second-line therapy in patients with sorafenib resistance. Sequential combination of sorafenib and PD98059 significantly reduced cell viability and proliferation, while increasing apoptosis efficacy in sorafenib-resistant cells. Conclusions: Our findings suggest that reactivation of the Raf/MEK/ERK pathway through aberrant expression of RKIP is one of the mechanisms for sorafenib resistance in HCC. Sequential combination treatment of sorafenib and PD98059 could provide a new strategy to overcome sorafenib resistance in future clinical studies.

Oncogenic potential of histone-variant H2A.Z.1 and its regulatory role in cell cycle and epithelial-mesenchymal transition in liver cancer

H2A.Z is a highly conserved H2A variant, and two distinct H2A.Z isoforms, H2A.Z.1 and H2A.Z.2, have been identified as products of two non-allelic genes, H2AFZ and H2AFV. H2A.Z has been reported to be overexpressed in breast, prostate and bladder cancers, but most studies did not clearly distinguish between isoforms. One recent study reported a unique role for the H2A.Z isoform H2A.Z.2 as a driver of malignant melanoma. Here we first report that H2A.Z.1 plays a pivotal role in the liver tumorigenesis by selectively regulating key molecules in cell cycle and epithelial-mesenchymal transition (EMT). H2AFZ expression was significantly overexpressed in a large cohort of hepatocellular carcinoma (HCC) patients, and high expression of H2AFZ was significantly associated with their poor prognosis. H2A.Z.1 overexpression was demonstrated in a subset of human HCC and cell lines. H2A.Z.1 knockdown suppressed HCC cell growth by transcriptional deregulation of cell cycle proteins and caused apoptotic cell death of HCC cells. We also observed that H2A.Z.1 knockdown reduced the metastatic potential of HCC cells by selectively modulating epithelial-mesenchymal transition regulatory proteins such as E-cadherin and fibronectin. In addition, H2A.Z.1 knockdown reduced the in vivo tumor growth rate in a mouse xenograft model. In conclusion, our findings suggest the oncogenic potential of H2A.Z.1 in liver tumorigenesis and that it plays established role in accelerating cell cycle transition and EMT during hepatocarcinogenesis. This makes H2A.Z.1 a promising target in liver cancer therapy.

Interleukin-22-Induced Antimicrobial Phospholipase A2 Group IIA Mediates Protective Innate Immunity of Nonhematopoietic Cells against Listeria monocytogenes.

Listeria monocytogenes is a bacterial pathogen which establishes intracellular parasitism in various cells, including macrophages and nonhematopoietic cells, such as hepatocytes. It has been reported that several proinflammatory cytokines have pivotal roles in innate protection against L. monocytogenes infection. We found that a proinflammatory cytokine, interleukin 22 (IL-22), was expressed by CD3(+) CD4(+) T cells at an early stage of L. monocytogenes infection in mice. To assess the influence of IL-22 on L. monocytogenes infection in hepatocytes, cells of a human hepatocellular carcinoma line, HepG2, were treated with IL-22 before L. monocytogenes infection in vitro. Gene expression analysis of the IL-22-treated HepG2 cells identified phospholipase A2 group IIA (PLA2G2A) as an upregulated antimicrobial molecule. Addition of recombinant PLA2G2A to the HepG2 culture significantly suppressed L. monocytogenes infection. Culture supernatant of the IL-22-treated HepG2 cells contained bactericidal activity against L. monocytogenes, and the activity was abrogated by a specific PLA2G2A inhibitor, demonstrating that HepG2 cells secreted PLA2G2A, which killed extracellular L. monocytogenes. Furthermore, colocalization of PLA2G2A and L. monocytogenes was detected in the IL-22-treated infected HepG2 cells, which suggests involvement of PLA2G2A in the mechanism of intracellular killing of L. monocytogenes by HepG2 cells. These results suggest that IL-22 induced at an early stage of L. monocytogenes infection enhances innate immunity against L. monocytogenes in the liver by stimulating hepatocytes to produce an antimicrobial molecule, PLA2G2A.

262. Directed Evolution of Improved AAV Capsids for the Ideal Human Liver Vector–Can Human Liver Tropism and Human Immune Evasion Be Achieved?

Research towards improved adeno-associated virus (AAV) delivery vectors for use in treating human liver diseases continues to be dominated by efforts to characterize potential candidate vectors in mice which often can't recapitulate either the human liver tropism/transduction profiles, or the specifics of the human immune response to these vectors. Research from our lab has shown that despite the impressive hepatocyte transduction levels by AAV-8 in mouse liver, AAV-8 does not functionally transduce human hepatocytes in xenografted humanized liver mouse models to levels of therapeutic relevance, possibly explaining the lower than expected FIX expression levels from the recent AAV-8 hemophilia clinical trial. Efforts to evolve novel capsid variants with improved human hepatocyte tropism were successful with the generation of AAV-LK03, yet limitations to clinical translation with many newly evolved serotypes remains due to high levels of pre-existing neutralizing antibodies that may cross-react and neutralize transduction. For this reason we sought to evolve improved hepatotropic variants–again in humanized liver mice–that not only retained robust human liver tropism, but also had been evolved for resistance to pre-existing neutralizing antibodies in the human population to create the ideal liver vector for use in the clinic. We utilized wild-type replicating AAV libraries of 10e5 variants via DNA shuffling of eleven different parental AAV capsids. Our libraries selectively replicate in human cells when co-administered with wild-type adenovirus, making chimeric humanized liver mice an excellent tool to allow for selection of capsids with tropism for human liver. Screens were carried out for five rounds of selection and rather than waiting for the screen to go to completion, we ended the screen with some library diversity remaining for use in a subsequent screen for neutralizing antibody evasion. All variants from round five of the human liver screen were carried forward and screened for two additional rounds for their ability to resist binding to pooled human immunoglobulins in IgG immunocapture assays. The top 100 highly selected variants were sequenced and vectorized into CAG-driven GFP preparations in seven pools based on capsid relatedness at the amino acid level. Each pool was then resubjected to additional pooled human immunoglobulin screening and the best pool was chosen. The top seven candidates from this pool were tested alongside control serotypes that represent the extremes for humoral neutralization: highest neutralization (AAV-2), lowest neutralization (AAV-DJ), as well as LK03 that falls in between. One variant from this highly selected pool has neutralization profiles on par with AAV-DJ and further characterizations are underway in humanized liver mice in vivo and various human hepatoma lines in vitro to determine if both desired characteristics were robustly retained—human liver tropism and human immune evasion.

Effect of Golgi phosphoprotein 2 (GOLPH2/GP73) on autophagy in human hepatocellular carcinoma HepG2 cells.

This study aims to investigate the effect of Golgi Protein 73 (GP73) on autophagy in human hepatoma line cells HepG2. We investigated the functional effects of GP73 on autophagy in hepatoma cell line HepG2 using immunofluoscence staining, Western blotting and real-time PCR. Our data showed that specific small interference RNA (siRNA) notably induced formation of autophagic vacuoles. In addition, upregulation of GP73 significantly inhibited formation of starvation-induced LC3-positive structures. We provide the first experimental evidence to show that GP73 may play an important role in the inhibitory regulation of autophagy. Therefore, our data suggest a new molecular mechanism for GP73-related hepatoma progression.

Abstract 1461: A miR-221 multigene pharmacodynamic signature for assessing miR-221 inhibition

Abstract miR-221 targets key cancer pathways, inhibits translation of important tumor suppressors, and is overexpressed in hepatocellular carcinoma (HCC). Aberrant miR-221 expression has been linked to HCC progression, while inhibition of miR-221 has been shown to reduce tumor growth. In preclinical models, miR-221 inhibition can be assessed by measuring de-repression of known miR-221 target genes such as p27. However, changes in individual microRNA target genes are often small and model-dependent; and comprehensive assessment of pharmacodynamic (PD) effects following microRNA inhibition is often challenging. Herein, we present a miR-221 multigene PD signature that can assess miR-221 target engagement with a large dynamic window and work across different human HCC models following miR-221 inhibition. In the first stage, we transfected five different human HCC lines with two chemically-modified oligonucleotides that inhibit miR-221 functions (miR-221 anti-miRs) and a microRNA-duplex that mimics miR-221/222 functions (mimic). The resulting global mRNA expression changes were compared to mock treated cells using GeneChip Human Genome U133 Plus 2.0 Array (Affymetrix). Ninety unique human genes with transcripts containing conserved and/or 8-mer target seeds (TargetScan), that significantly went up and down after anti-miR-221s and mimic treatment respectively, were further profiled with qPCR in the second stage. Out of the 90 tested transcripts, 62 of them were significantly up-regulated by anti-miR-221s but not by control oligonucleotides (either mismatch or targeting unrelated microRNAs). From the 62 genes, an optimal multigene signature consisted of 13 unique human genes normalized by 6 reference housekeeping genes was identified. We also devised a “miR-221 signature score” and demonstrated that our multigene signature can separate miR-221 anti-miRs treatment from control oligonucleotides with a high degree of sensitivity and specificity. We further validated this multigene signature by demonstrating that it correctly distinguished miR-221 anti-miRs treatment from controls in three additional HCC cell lines in vitro and one HCC model in vivo. In summary, our miR-221 multigene PD signature analysis provided a comprehensive assessment of miR-221 inhibition, with significantly larger dynamic window compare to individual gene analysis, that may be used to discover, rank order and guide the development of novel miR-221 anti-miRs for the treatment of human cancers. Citation Format: Adam Pavlicek, Thomas Vincent, Oivin Guicherit, Nelson Chau, Sonya Zabludoff, Neil Gibson, Edmund C. Lee. A miR-221 multigene pharmacodynamic signature for assessing miR-221 inhibition. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1461. doi:10.1158/1538-7445.AM2014-1461

Inhibition of fibroblast growth factor receptor signaling impairs metastasis of hepatocellular carcinoma

The molecular mechanism underlying metastasis of hepatocellular carcinoma (HCC) remains elusive. Here, we showed that matrix metalloproteinase (MMP) 7 and MMP26 levels are significantly higher in the resected HCC than in the adjacent healthy hepatic cells from the patients. Moreover, a strong correlation of the levels of MMP7 or MMP26 with the phosphorylated fibroblast growth factor receptor 2 (FGFR2) was detected. To prove a causal link between the activation of FGFR signaling pathway and expression of MMP7 and MMP26, we used two human HCC lines, HepG2 and HuH-7, to study the underlying molecular basis. We found that FGF1-induced FGFR2 phosphorylation in either line resulted in significant activation of MMP7 and MMP26 and consequently an increase in cancer invasiveness. Inhibition of FGFR2 phosphorylation in HCC abolished FGF1-stimulated MMP7 and MMP26 expression, suggesting that activation of the FGFR signaling pathway in HCC may promote cancer metastasis by inducing MMP7 and MMP26 expression. To define the signal transduction cascades downstream of FGFR2 activation for MMP7 and MMP26 activation, we applied specific inhibitors for phosphatidylinositol-3 kinase (PI3K), extracellular signal-related kinase/mitogen-activated protein kinase (ERK/MAPK), and Jun N-terminal kinase (JNK), respectively, to the FGF1-stimulated HCC cells. We found that only inhibition of JNK significantly decreased the activation of MMP26 in response to FGF1 stimulation, and only inhibition of PI3K significantly decreased the activation of MMP7 in response to FGF1 stimulation, suggesting that the activation of the FGFR2 signaling may activate PI3K to activate MMP7 and activate JNK to activate MMP26, in HCC. Our study thus highlights the FGFR2 signaling pathway and MMP7 and MMP26 as novel therapeutic targets for HCC.

Human pathophysiological concentrations of bile salts induce necrosis in primary human hepatocytes (398.1)

Liver injury during cholestasis is thought to develop due to plasma and liver accumulation of toxic bile salts (BS), such as glycochenodeoxycholate (GCDC), which leads to apoptosis. This paradigm relies on the use of cytotoxic concentrations of GCDC to mimic cholestasis in rat hepatocytes or human hepatoma lines. Instead, this study assessed how pathophysiological concentrations of BS measured in cholestatic patients affected primary human hepatocytes (PHH). Individual BS levels were determined by UPLC/MS in 50 patients with extrahepatic cholestasis, with or without concurrent liver injury. Patients with liver injury had increased BS levels in serum, while biliary levels decreased, implicating development of bile infarcts, which were confirmed by histology. Human hepatocytes isolated from resection material, retained functional BS uptake via Na+ ‐dependent and ‐independent transporters, measured by uptake of taurocholate. Exposing PHH to GCDC for 6 hours resulted in little cell death, measured by LDH release, until exposure to concentrations >1mM GCDC. In contrast to data in rat hepatocytes, no dose of GCDC produced an increase in caspase‐3 activity in PHH, and pretreatment with a pan‐caspase inhibitor did not protect. Finally, PHH were treated with complete BS mixtures derived from patient serum or bile. While serum values resulted in no increase in cell death for up to 24 hours after application, bile mixtures caused direct toxicity. These data suggest PHH are more resistant to human BS concentrations than rat hepatocytes, and die by necrosis. Moreover, biliary concentrations of BS are required for acute cell death, implicating biliary infarction as the initiator of injury.

Abstract 5235: A model for TNFα-mediated NFκB signalling: A systems biology study on hepatocytes and liver cancer cells.

Abstract It is known that the development of hepatocellular carcinoma (HCC) is frequently associated to inflammation, hepatocytic inhibition of apoptosis, and compensatory liver regeneration. In this context, the classical κ-light-chain-enhancer of activated B cells (NFκB) signaling pathway is one central regulator of inflammatory responses and hepatocyte survival, which may promote HCC development. Upon stimulation, Kupffer cell-derived cytokine tumor necrosis factor (TNF)-α is one of the key factors during the priming phase of liver regeneration as well as in hepatocarcinogenesis mainly driving cell survival and proliferation by NFκB signalling pathway. In order to understand the impact of this pathway in the earliest stages of liver damage and tumorigenesis, mathematical modelling is necessary to describe the dynamic behaviour of this pathway in normal as well as in malignant-transformed cells. Several mathematical models have been developed for TNFα-induced NFκB signalling in immortalized fibroblasts and tumor cell lines; however, a model specifically analyzing and comparing hepatocytes and HCC cells is still missing. We here present a hepatocyte-specific ordinary differential equation (ODE) model for TNFα-induced NFκB signaling that considers experimental data of protein expression after TNFα stimulation (p65/pp65, IκBα/pIκBα), basal protein turnover (p65, IκBα), and IκBα mRNA. In order to sufficiently describe the pathway dynamics, an additional nuclear phosphorylation step of p65 was included in the model. Possible candidate kinases are the mitogen- and stress-activated protein kinase1 (MSK1) and the protein kinase C zeta (PKCζ). The established model was able to predict TNFα-induced p65/IκBα complex formation, which was experimentally confirmed using primary mouse hepatocytes cells. Finally, we compared the dynamics of TNFα-induced NF-kB pathway activation in different species and cell types (primary murine hepatocytes, human and mouse HCC lines, mouse liver tissue after partial hepatectomy). In conclusion, we here present a mathematical model for TNFα/NFκB signalling in primary hepatocytes cells, providing an important basis to quantitatively disentangle the complex processes factors in liver regeneration and tumorigenesis. Citation Format: Federico Pinna, Sven Sahle, Katharina Beuke, Michaela Bissinger, Selcan Tuncay, Lorenza D'Alessandro, Ralph Gauges, Andreas Raue, Jens Timmer, Ursula Klingmüller, Peter Schirmacher, Ursula Kummer, Kai Breuhahn. A model for TNFα-mediated NFκB signalling: A systems biology study on hepatocytes and liver cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5235. doi:10.1158/1538-7445.AM2013-5235

Abstract 3479: Targeting FoxM1 selectively depletes hepatic cancer stem cells

Abstract Over-expression of the Forkhead box M1 (FoxM1) transcription factor coincides with highly aggressive, poorly differentiated hepatocellular carcinoma (HCC). Over-expression of FoxM1 in HCC also correlates with poorer overall survival after hepatectomy. Since HCC progression involves hepatic cancer stem cells (HCSCs), we considered the roles of FoxM1 in HCSCs. We found that FoxM1 expression correlates with the expression of the stemness genes in human HCC cell lines. Interestingly, depletion of FoxM1 in human HCC lines causes a selective reduction in the population of the CD90+ HCSCs due to selective apoptosis. Moreover, FoxM1 silencing decreases sphere formation potential of the same cell lines, suggesting that FoxM1 is critical for survival of the HCSCs. Consistent with the loss of HCSCs, depletion of FoxM1 causes decrease in tumorigenic potential of the HCC cells in vitro as well as inhibition of tumor formation in mouse xenografts. Furthermore, we found that FoxM1 directly regulates expression of CD44, previously shown to be important for the tumorigenic potential of CD90+ HCC cells. These studies have exciting implications in further considerations of FoxM1 as a target of HCC therapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3479. doi:1538-7445.AM2012-3479

Abstract 5148: Amino acid transporters ASCT2 and LAT1 ubiquitously function in N-myc (+) epithelial and mesenchymal human HCC cells exhibiting a wide array of mTOR and glycolytic reliance for growth

Abstract Amino acid transporters ASCT2 and LAT1 are coordinately enhanced in a broad array of human cancers where they associate in the plasma membrane and are proposed to work cooperatively to activate mTOR signaling through a tertiary-active transport mechanism involving glutamine (ASCT2) and essential branch-chain amino acids (LAT1). Silencing of ASCT2 expression in liver cancer cells has been shown to induce apoptosis and inhibit mTOR signaling while Myc expression has been implicated in promoting ASCT2 and LAT1 expression as well as a glutamine-intensive metabolic profile typical of many cancers, which helps support the switch to aerobic glycolysis (Warburg effect). In particular, ASCT2 and LAT1 are nearly undetectable in normal liver but are enhanced in hepatocellular carcinoma (HCC). To test the relationship between amino acid transporters, myc expression, metabolism and mTOR, we examined the expression and function of ASCT2 and LAT1 as a function of N-myc and C-myc status, reliance on glycolysis for growth and sensitivity to rapamycin (mTOR) in a broad panel of 14 human HCC lines (7 Group I (epithelial) and 7 Group II (mesenchymal)). We hypothesized that transporter expression is proportional to myc expression, and that glycolytic reliance and both transporters are enhanced in the more aggressive Group II HCC lines. Our results show that all human HCC lines are N-myc-, ASCT2- and LAT1-positive, and variably c-myc positive, with no clear correlation between specific myc isoform and transporter expression levels. In general, LAT1 protein expression was uniformly high in all mesenchymal HCC lines, but more variable in epithelial HCC, while BCH-inibitable leucine uptake rates displayed a wide array of values in both HCC groups; the same was true for ASCT2 protein and glutamine uptake activities. Treatment of HCC cells for 24 hours with ASCT2 and LAT1 substrate inhibitors GPNA and BCH, respectively, failed to inhibit mTOR signaling as indexed by 4EBP1 phosphorylation. Inhibition of glycolysis and growth with 3-bromopyruvate was generally more pronounced in epithelial HCC, but variably evident in both HCC groups. Rapamycin-dependent growth inhibition was variable between HCC lines and showed no preferential epithelial or mesenchymal HCC efficacy. Collectively, the results suggest that N-myc, ASCT2 and LAT1 are ubiquitously expressed in both epithelial and mesenchymal human HCC cells, where they help drive growth in cells variably reliant on mTOR signaling and glycolysis. Thus, both transporters remain the subject of ongoing investigation as targeted therapies for HCC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5148. doi:1538-7445.AM2012-5148

Abstract 4429: An investigation on p21-activated protein kinase 1 inhibitor, IPA-3, in hepatocellular carcinoma

Abstract Background: Hepatocellular carcinoma (HCC) is one of the major malignancies worldwide and is associated with poor prognosis due to metastasis and tumor recurrence. However, apart from Sorafenib, there is no proven effective systemic chemotherapy for HCC yet. Our previous study showed that overexpression of p21-activated protein kinase 1 (PAK1) is commonly found in HCC, which is coupled with a more aggressive tumor behavior. In this study, we examined the effect of an allosteric inhibitor of PAK1, IPA-3, on hepatocarcinogenesis. Methods: Human HCC line H2M was treated with various dosages of IPA-3 or vehicle control in order to measure the phospho-PAK1 level. The cells were also subjected to different functional assays, including proliferation assay, transwell assay and colony formation assay, to examine the anti-cancer effect of IPA-3. Tumor xenografts in nude mice were used to examine the in vivo activity of IPA-3. Results: Pretreatment with IPA-3 dose-dependently suppressed fetal bovine serum (FBS)-, and tumor necrosis factor (TNF)-α-induced PAK1 activity. The inhibitory effect was causally accompanied with suppression on cell migration, and enhancement of cell spreading. Furthermore, IPA-3 treatment on HCC cell line demonstrated a suppression of cell growth. The concomitant increase in apoptosis and delay in DNA synthesis had suggested a mechanism explaining the inhibition of HCC proliferation. In vivo, intraperitoneal administration of IPA-3 to subcutaneous xenograft mouse model significantly reduced the tumor growth rate. Conclusion: Taken together, these data showed that IPA-3 restrains cancer cell tumorigenicity and metastasis, thus, suggesting the potential use of IPA-3 in cancer therapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4429. doi:1538-7445.AM2012-4429

A Hepatocellular Carcinoma Tumor Marker and Hedgehog Pathway Mediator, Glypican-3, Inhibits Hepatic Stellate Cell Viability: A Novel Outcome of Hepatic Tumor-Stroma Interactions

Introduction: Human hepatocellular carcinoma (HCC) is one of the deadliest cancers worldwide, and its incidence is rapidly increasing in the U.S. HCC is truly 2 diseases in 1 as it often arises in the setting of cirrhosis. We previously identified dysregulation of the Hedgehog (Hh) pathway as a novel mechanism for hepatocarcinogenesis and identified a role for Hh signaling in maintaining the viability and regulating the fibrinogenic capacity of hepatic stellate cells (HSC), which are implicated in cirrhosis. It is increasingly recognized that HSCs and HCCs can communicate via paracrine signaling, but Hh signaling has not been studied in this process. We hypothesized that a secreted HCC tumor marker and Hh mediator, Glypican-3 (GPC3), may play a role in regulating HCC (tumor)-HSC (stroma) interactions. Methods: We developed an in vitro co-culture (CC) model system with Transwell plates to recapitulate HCC-HSC interactions in order to assess HCC effects upon HSC viability, apoptosis, and gene transcription. We employed 2 Hh-responsive human HCC lines [PLC/PRF/5 (PLC) and SK-Hep1 (SK)] and 1 human HSC line (LX-2). Assays for cell viability (WST) and apoptosis (caspase-3/7 activity) were performed (48-72 h, N=3-9). Using real-time RT-PCR, mRNA expression of Hh target genes was studied. Western analysis was used to study GPC3 protein expression during CC. Recombinant human GPC3, as well as other Hh ligand inhibitors were analyzed for effects. Results: Using our CC system, both HCC lines had no effect upon HSC viability but caused a reduction in HSC apoptosis by 2% (SK) and 50% (PLC). This suggested that HCCs secrete paracrine factor(s) that increase HSC apoptosis and decrease HSC proliferation. Concomitantly, CC resulted in transcriptional downregulation of the Hh target gene, Gli1 (SK: 1.5-fold, PLC: 2.7-fold). at baseline, real-time RT-PCR showed that PLC expressed >73,600-fold more Gpc3 mRNA than SK. CC led to a mixed response in Gpc3 mRNA levels with a 7.3-fold decrease in PLC mRNA but 4.5-fold increase in SK mRNA. at the protein level, GPC3 was strongly expressed in both lines after CC. to determine if GPC3 affects HSCs, we treated LX-2 with GPC3 (5 μg/ml). This resulted in an 83.4% reduction in HSC viability at 48 h. Similar effects were seen with 2 other anti-Hh treatments [5E1 (anti-Hh antibody) and HIP (Hh-interacting protein)]. Conclusions: For the first time, we show that HCC-HSC interactions lead to downregulation of Hh signaling in HSC. in part, this appears to be mediated by HCC's paracrine secretion of GPC3, an HCC biomarker, which inhibits Hh signaling and HSC viability. the underlying reasons for this inhibition remain unclear but may be related to GPC3 regulation of peritumoral angiogenesis. in summary, we expand upon data suggesting a role for tumor-stroma interactions in hepatic carcinogenesis-fibrinogenesis. These findings may have clinical implications, as a trial is underway to investigate the efficacy of anti-GPC3 therapy for HCC.

Differential expression of Rab27A/B correlates with clinical outcome in hepatocellular carcinoma

To investigate the association of Rab27A and Rab27B expression with clinicopathological characteristics and prognosis of hepatocellular carcinoma (HCC). We used reverse transcription polymerase chain reaction (RT-PCR), real-time PCR, and Western blotting to detect Rab27A and Rab27B mRNA and protein expression in 5 human HCC lines and the immortalized hepatic HL-7702 cell line. We further examined 148 primary HCC samples matched with adjacent normal tissue and 80 non-HCC specimens by immunohistochemistry to evaluate the correlation of Rab27A and Rab27B expression with clinicopathological features and prognosis. Our data showed that Rab27A and Rab27B were differentially expressed in cell lines and primary HCC tumors. Rab27A mRNA and protein were detected in 67% (4/6) of human cell lines and 80% (4/5) of HCC cell lines, while Rab27B was found in 50% (3/6) of human lines and 40% (2/5) of HCC lines. Rab27A expression was higher in primary HCC (46.2%, 66/143) than in matched adjacent tissue (24.3%, 33/136, P < 0.001), whereas immunopositivity for Rab27B was lower in primary HCC (57.4%, 81/141) than in matched adjacent tissue (87.5%, 119/136, P < 0.001). Analysis of clinicopathological characteristics of 148 HCC specimens revealed significant correlations between Rab27A and Rab27B expression and tumor tumor-node-metastasis (TNM) classification (P = 0.046 and P = 0.027, respectively), and between strong Rab27A expression and tumor differentiation grade (P = 0.008). Survival analyses revealed that patients with Rab27A(+) or Rab27B(+) tumors had significantly reduced overall survival compared with that of patients with Rab27A(-) or Rab27B(-) tumors (P = 0.015 and P = 0.005, respectively). Risk analyses revealed that Rab27B(+) and TNM III-IV were independent poor prognosis factors associated with a 3.36- and 3.37-fold higher relative risk of death, respectively. Rab27A and Rab27B expression were closely correlated with tumor progression and can be valuable prognostic indicators for HCC patients.

Scoparone potentiates transactivation of the bile salt export pump gene and this effect is enhanced by cytochrome P450 metabolism but abolished by a PKC inhibitor

Hyperbilirubinaemia and cholestasis are two major forms of liver abnormality. The Chinese herb Yin Chin has been used for thousands of years to treat liver dysfunctions. In mice, this herb and its principal ingredient scoparone were found to accelerate the clearance of bilirubin accompanied by the induction of uridine diphosphate-5'-glucuronosyltransferase-1A1 (UGT1A1), a bilirubin processing enzyme. The aim of this study was to determine whether scoparone induces the expression of human UGT1A1. In addition, the expression of the bile salt export pump (BSEP), a transporter of bile acids, was determined. Primary human hepatocytes and hepatoma line Huh7 were treated with scoparone, chenodeoxycholic acid (CDCA) or both. The expression of UGT1A1 and BSEP mRNA was determined. The activation of the human BSEP promoter reporter by scoparone was determined in Huh7 cells by transient transfection and in mice by bioluminescent imaging. The metabolism of scoparone was investigated by recombinant CYP enzymes and pooled human liver microsomes. Scoparone did not enhance the expression of either human BSEP or, surprisingly, UGT1A1. However, scoparone significantly potentiated the expression of BSEP induced by CDCA. Consistent with this, scoparone potentiated the stimulant effect of CDCA on the human BSEP promoter. This potentiation was enhanced by co-transfection of cytochrome P4501A2 but abolished by the PKC inhibitor GF109203X. Scoparone and Yin Chin normalize liver function primarily by enhancing the secretion of bile acids, and this effect probably varies depending on the metabolic rate of scoparone.