ag-490 and Liver-Neoplasms

Transforming growth factor β1 (TGFβ1) is a cytokine with multiple functions. TGFβ1 significantly induces migration and invasion of liver cancer cells. However, the molecular mechanisms underlying this effect remain unclear. Epithelial‑to‑mesenchymal transition (EMT) is crucial for the development of invasion and metastasis in human cancers. The aim of the present study was to determine whether TGFβ1‑induced EMT promoted migration and invasion in HepG2 cells. The underlying mechanism and the effect of EMT on HepG2 cells were also investigated. The results demonstrated that TGFβ1 may induce EMT to promote migration and invasion of HepG2 cells, and this effect depends on activation of the Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) signaling pathway. JAK/STAT3 signaling is involved in human malignancies, including lung cancer, and is implicated in cell transformation, tumorigenicity, EMT and metastasis. In the present study, TGFβ1 also activated JAK/STAT3 signaling in HepG2 cells and promoted Twist expression, but these events were abolished by treatment with the STAT3 inhibitor AG490. Additionally, Twist siRNA blocked TGFβ1‑induced EMT. Thus, TGFβ1 was shown to induce EMT, thereby promoting the migration and invasion of HepG2 cells via JAK/STAT3/Twist signaling.

Topics: Cell Movement; Cell Proliferation; Epithelial-Mesenchymal Transition; Gene Expression Regulation, Neoplastic; Hep G2 Cells; Humans; Janus Kinases; Liver Neoplasms; Neoplasm Invasiveness; Neoplasm Metastasis; RNA, Small Interfering; Signal Transduction; STAT3 Transcription Factor; Transforming Growth Factor beta1; Twist-Related Protein 1; Tyrphostins

Epidermal growth factor receptor (EGFR) is frequently aberrantly expressed in cancer, and abnormal signalling downstream of this receptor contributes to tumour growth. EGFR variant III (EGFRvIII) is the most commonly altered form of EGFR and contains a truncated ligand-binding domain. Aberrant signalling downstream of this receptor contributes to tumour invasion. We previously reported that EGFRvIII can promote hepatocellular carcinoma (HCC) invasion. However, little is known concerning the mechanisms underlying EGFRvIII-mediated increases in cell motility and invasion in HCC. In this study, we observed that S100A11 was significantly upregulated in Huh-7 cells that overexpressed EGFRvIII. Moreover, S100A11 expression was elevated in HCC tissue samples (68.6%; 35/51), and this elevation was correlated with EGFRvIII expression (p = 0.0020; n = 20). Furthermore, the overexpression of S100A11 can promote HCC cell invasiveness, whereas siRNA against S100A11 can suppress the invasiveness of HCC cells stably transfected with EGFRvIII. Additionally, STAT3 inhibitors can block S100A11 expression and S100A11 promoter activity in HCC cells with stable overexpression of EGFRvIII. Furthermore, mutation in STATx binding sites could abolish the S1000A11 promoter activity stimulation by EGFRvIII. Taken together, the results demonstrate that the EGFRvIII-STAT3 pathway promotes cell migration and invasion by upregulating S100A11.

Topics: Carcinoma, Hepatocellular; Cell Line, Tumor; ErbB Receptors; Gene Expression Regulation, Neoplastic; Humans; Liver Neoplasms; Mutation; Neoplasm Invasiveness; Promoter Regions, Genetic; RNA, Small Interfering; S100 Proteins; Signal Transduction; STAT3 Transcription Factor; Tyrphostins

The activation of signal transducer and activator of transcription signaling 3 (STAT3) has been linked with the survival, proliferation, angiogenesis and immunosuppression of hepatocellular carcinoma cells (HCCs). Agents that can suppress STAT3 activation have potential to be cancer therapeutics. In this study, we investigated the inhibitory effect of evodiamine on STAT3 pathway in vitro and the anti-tumor effect of evodiamine in vivo in HCC. We found that evodiamine suppressed both constitutive and interleukin-6 (IL-6)-induced activation of STAT3 tyrosine 705 (Tyr(705)) effectively. The phosphorylation of Janus-activated kinase 2 (JAK2), Src and extracellular regulated protein kinases 1/2 (ERK1/2) were also suppressed by evodiamine. Interestingly, treatment of cells with sodium pervanadate abrogated the inhibition of evodiamine on IL-6-induced STAT3 (Tyr(705)) activation indicating the involvement of protein tyrosine phosphatases. Indeed, further studies demonstrated that evodiamine induced the expression of phosphatase shatterproof 1 (SHP-1). Moreover, inhibition of SHP-1 gene by small interference RNA abolished the ability of evodiamine to inhibit IL-6-induced STAT3 (Tyr(705)) activation. Evodiamine also suppressed STAT3 DNA binding activity and down-regulated the expression of STAT3-mediated genes leading to the suppression of proliferation, induction of cell apoptosis and cell cycle arrest. In vivo, evodiamine significantly inhibited tumor growth in a subcutaneous xenograft model with HepG2 cells. In summary, evodiamine blocked STAT3 signaling pathway by inducing SHP-1 and exhibited anticancer effect in vitro and in vivo.

Topics: Animals; Apoptosis; Carcinoma, Hepatocellular; Cell Cycle Checkpoints; Cell Cycle Proteins; Cell Line, Tumor; Enzyme Activation; Female; Gene Expression Regulation, Neoplastic; Hep G2 Cells; Humans; Interleukin-6; Janus Kinase 2; Liver Neoplasms; Mice; Mice, Nude; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Phosphorylation; Protein Tyrosine Phosphatase, Non-Receptor Type 6; Quinazolines; RNA Interference; Signal Transduction; src-Family Kinases; STAT3 Transcription Factor; Tyrphostins; Xenograft Model Antitumor Assays

Although cancer stem cells (CSCs) are believed to be the key drivers in tumor growth and resistance to therapy, the specific signaling of CSCs is largely unknown. In this study, we evaluated the roles of hypoxia and STAT3 signaling on the treatment resistance of CSCs. Side population (SP) cell analysis and sorting were used to detect subpopulations that function as CSCs. Huh-7 cells, doxorubicin, sulfaphenazole (a CYP2C9 inhibitor), and AG490 (a STAT3 inhibitor) were used in this study. Cell growth and apoptosis were assessed using MTS assays, and apoptotic and kinase signaling pathways were explored by immunoblotting. Treatment with IL-6 induced STAT3 activation more significantly in SP than non-SP cells. Hypoxia induced SP cell proliferation, and microarray analysis showed that the expression of CYP2C9 was significantly increased in hypoxic than normoxic SP cells. Although hypoxic SP cells were less sensitive to doxorubicin-induced apoptosis, pretreatment with sulfaphenazole sensitized hypoxic SP cells to doxorubicin cytotoxicity. These results indicate that STAT3 is critical for CSC survival and hypoxia-inducible CYP2C9 expression is responsible the doxorubicin resistance of CSCs under hypoxic conditions. Thus, the selective inhibition of CYP2C9 and STAT3 may be implicated in the sensitization of CSCs to anti-cancer treatment, particularly in advanced cases.

Topics: Antineoplastic Agents; Apoptosis; Aryl Hydrocarbon Hydroxylases; Carcinoma, Hepatocellular; Cell Hypoxia; Cell Proliferation; Cytochrome P-450 CYP2C9; Doxorubicin; Drug Resistance, Neoplasm; Flow Cytometry; Humans; Immunoblotting; Interleukin-6; Liver Neoplasms; Side-Population Cells; Signal Transduction; STAT3 Transcription Factor; Sulfaphenazole; Tyrphostins

To examine how the thymidine phosphorylase (TP) gene expression is upregulated by interferon-alpha (IFN-alpha) in human hepatocellular carcinoma SMMC-7721 cells.. TP mRNA levels were determined by RT-PCR. Whether the JAK-STAT cascade mediates IFN-alpha-induced TP mRNA expression was studied by pretreatment with Janus Kinase (JAK) inhibitor, AG-490. Effects of IFN-alpha on TP mRNA stability were detected with additional actinomycin D.. The expression of TP mRNA was induced by IFN-alpha in a dose- and time-dependent manner in SMMC-7721 (human hepatocellular carcinoma) cells. TP mRNA levels rose at 8 h, reached the peak value at 12 h, and remained at a high level up to 72 h in SMMC-7721 cells treated with IFN-alpha 10000 U/ml. IFN-alpha at a dose of 5000 or 10000 U/ml up-regulated TP expression about 3 fold compared with that of non-treated cells (P < 0.05). Induction of TP mRNA expression by IFN-alpha was significantly inhibited in SMMC-7721 cells by pretreatment with AG-490, in comparison with that treated with IFN-alpha alone. Pretreatment of SMMC-7721 cells with IFN-alpha 10000 U/ml for 24 h caused a substantial stabilization of TP mRNA, with a half-live of 35.8 h, compared with 8.5 hr in the control SMMC-7721 cells.. IFN-alpha at certain doses upregulates TP mRNA expression via both JAK-STAT transcriptional activation and post-transcriptional mRNA stabilization in human hepatocellular carcinoma SMMC-7721 cells.

Topics: Carcinoma, Hepatocellular; Cell Line, Tumor; Dose-Response Relationship, Drug; Enzyme Inhibitors; Gene Expression Regulation, Neoplastic; Humans; Interferon-alpha; Janus Kinases; Liver Neoplasms; RNA, Messenger; STAT1 Transcription Factor; Thymidine Phosphorylase; Transcriptional Activation; Tyrphostins

Signal transducer and activator of transcription 3 (STAT3) is constitutively activated and regulates cell growth and survival of various cancer cells. We investigated the anti-tumor effect of AG490, a Janus kinase 2 specific inhibitor, inhuman hepatoma cells.. Effects of AG490 on STAT3 activation, on cell-growth and survival, and on the expression of cell-cycle- and apoptosis-related proteins were evaluated in Huh-1, Huh-7, HepG2 and Hep3B cells. Next, whether AG490 renders hepatoma cells susceptible to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) was examined in vitro and in vivo.. Constitutively activated STAT3 through tyrosine phosphorylation was detected in all hepatoma cells. AG490 inhibited the phosphorylation of STAT3 and its activity. AG490 induced cell cycle arrest in Huh-1, Huh-7 and HepG2 through cyclin D1 downregulation, and induced marked apoptosis in Hep3B. AG490 downregulated at least one of the anti-apoptotic proteins, Bcl-xL, survivin or XIAP in all hepatoma cells. AG490 sensitized Huh-1, Huh-7 and HepG2 to TRAIL-induced apoptosis in vitro. Intraperitoneal injection of AG490, the combination of AG490 and TRAIL more greatly, repressed the growth of subcutaneous Huh-7 tumors in athymic mice.. Abrogation of constitutive activation of STAT3 by AG490 enhances the anti-tumor activity of TRAIL against human hepatoma cells.

Topics: Animals; Antineoplastic Agents; Apoptosis; Carcinoma, Hepatocellular; Cell Line, Tumor; Cyclin D1; Humans; Janus Kinase 2; Liver Neoplasms; Mice; Mice, Nude; Phosphorylation; STAT3 Transcription Factor; TNF-Related Apoptosis-Inducing Ligand; Tyrphostins; Xenograft Model Antitumor Assays

Signal transducer and activator of transcription 3 (STAT3) is constitutively activated in various cancers and plays a crucial role in oncogensis, including the activation of genes encoding apoptosis inhibitors and cell-cycle regulators. We investigated the biological significance of the Janus kinase (Jak)-STAT pathway in human hepatocellular carcinoma (HCC). Constitutive activation of STAT3 was seen in 49.4% of human HCC specimens and in HCC cell lines. Jak inhibitor AG490 inhibited activation of STAT3 and markedly reduced cell viability without significant apoptosis. AG490 also induced S phase cell-cycle arrest with down-regulation of cyclin D1, A, E and up-regulation of p21, p27, phospho-Chk2. AG490 also inhibited caspase inhibitory proteins, such as XIAP and survivin, and augmented TRAIL-induced apoptosis. Our study suggests that the Jak-STAT pathway plays an important role in cell-cycle progression and resistance to apoptosis. Inhibition of the Jak-STAT pathway may thus be a therapeutic target for HCC.

Topics: Apoptosis; Carcinoma, Hepatocellular; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Dose-Response Relationship, Drug; Enzyme Inhibitors; Flow Cytometry; Humans; Immunoblotting; Immunohistochemistry; Janus Kinases; Liver Neoplasms; Phosphorylation; S Phase; STAT3 Transcription Factor; TNF-Related Apoptosis-Inducing Ligand; Tyrphostins

Hepatitis C virus (HCV) infection is a leading cause a of chronic liver disease worldwide. The main therapeutic regimen is the combination of interferon alpha (IFN) and the nucleoside analog, Ribavirin. IFN initiates an intracellular antiviral state by the JAK-STAT signaling pathway, including a presumed role for STAT1 and STAT2. We have previously shown that the STAT3 activation occurs during IFN treatment of human hepatoma cells, suggesting that the STAT3-mediated pathway is relevant to IFN-induced antiviral activity. In this study, we investigate the role of activated STAT3 in the induction of anti-HCV activity in human hepatoma cells. We demonstrate that the STAT3 activation is involved in efficient IFN-induced anti-HCV activity. Using an inducible, cytokine-independent, STAT3 activation system, in which the entire coding region of STAT3 is fused with the ligand-binding domain of the estrogen receptor, we demonstrate that: activated STAT3 is tightly regulated in a stably transfected cell line by an estrogen analog, 4-HT; activated STAT3 initiates efficient anti-HCV activity in a HCV subgenomic replicon cell line; and activation of STAT3 is associated with the induction of a potential antiviral gene, 1-8U. In addition, we show that the cytokine IL-6, a potent STAT3 activator, inhibits HCV subgenomic RNA replication through STAT3 activation and ERK pathway. These results strongly suggest that STAT3 activation is capable of initiating intracellular antiviral pathways.

Topics: Antiviral Agents; Blotting, Northern; Blotting, Western; Carcinoma, Hepatocellular; Cell Line; Cell Line, Tumor; Cytokines; DNA-Binding Proteins; Dose-Response Relationship, Drug; Enzyme Inhibitors; Genes, Dominant; Hepacivirus; Humans; Inflammation; Interferons; Interleukin-6; Ligands; Liver; Liver Neoplasms; Luciferases; Plasmids; Protein Structure, Tertiary; Reverse Transcriptase Polymerase Chain Reaction; Ribavirin; RNA; RNA, Messenger; STAT3 Transcription Factor; Time Factors; Trans-Activators; Transfection; Tyrphostins

Hepatocellular carcinoma (HCC) is a major cause of cancer death, but the molecular mechanism for its development beyond its initiation has not been well characterized. Suppressor of cytokine signaling (SOCS-1; also known as JAB and SSI-1) switches cytokine signaling 'off' by means of its direct interaction with Janus kinase (JAK). We identified aberrant methylation in the CpG island of SOCS-1 that correlated with its transcription silencing in HCC cell lines. The incidence of aberrant methylation was 65% in the 26 human primary HCC tumor samples analyzed. Moreover, the restoration of SOCS-1 suppressed both growth rate and anchorage-independent growth of cells in which SOCS-1 was methylation-silenced and JAK2 was constitutively activated. This growth suppression was caused by apoptosis and was reproduced by AG490, a specific, chemical JAK2 inhibitor that reversed constitutive phosphorylation of STAT3 in SOCS-1 inactivated cells. The high prevalence of the aberrant SOCS-1 methylation and its growth suppression activity demonstrated the importance of the constitutive activation of the JAK/STAT pathway in the development of HCC. Our results also indicate therapeutic strategies for the treatment of HCC including use of SOCS-1 in gene therapy and inhibition of JAK2 by small molecules, such as AG490.

Topics: Antineoplastic Agents; Carcinoma, Hepatocellular; Carrier Proteins; CpG Islands; DNA Methylation; DNA-Binding Proteins; Gene Silencing; Genes, Tumor Suppressor; Genetic Therapy; Humans; Intracellular Signaling Peptides and Proteins; Janus Kinase 2; Liver Neoplasms; Molecular Sequence Data; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Repressor Proteins; Signal Transduction; STAT3 Transcription Factor; Suppressor of Cytokine Signaling 1 Protein; Suppressor of Cytokine Signaling Proteins; Trans-Activators; Tyrphostins