Human Hepatocellular Cancer Cell Lines Research Articles

A potent antitumor polysaccharide from the edible brown seaweedHydroclathrus clathratus

AbstractA sulfated polysaccharide H3-a1 [designated polysaccharide fraction, H3-a1, ofHydroclathrus clathratus(HCP)] was isolated and purified from an edible brown seaweedHydroclathrus clathratus; HCP contained about 8.6% protein and a relatively high sulfur content (8.2%). HCP significantly affected the growth of human acute promyelocytic leukemia cells (HL-60), human breast carcinoma (MCF-7) and human hepatocellular carcinoma cancer cell lines. As revealed by flow cytometry, when HCP was co-incubated with HL-60 and MCF-7 cells for 72 h, it induced significant sub-G1 arrest (apoptosis) of these cells. HCP caused G1 phase arrest but did not induce terminal differentiation of these cancer cells.In vivoantitumor tests showed that HCP inhibited tumor growth at doses of 20 and 50 mg kg-1in tumor-bearing BALB/c (supplied by the Laboratory Animal Services Centre of The Chinese University of Hong Kong) mice, but this effect was not due to anin vivoinhibitory effect on tumorigenesis. Nevertheless, HCP suppressed ascitic Sarcoma 180 tumor growth and prolonged the life span of the tumor-bearing mice by about 30–40%. HCP had no observed toxic side effects; it did not affect blood cells, or body, liver or spleen weights of mice 4, 7 and 10 days after treatment. This sulfated polysaccharide induced increased tumor necrosis factor-alpha (TNF-α) level in mouse serum. It also activated peritoneal macrophages to secrete TNF-α and nitric oxide.

Abstract 3884: Beta-2 spectrin opposes the CDK4-mediated suppression of TGF-beta signaling by rescuing Smad3 nuclear localization

Abstract Background: Transforming growth factor beta (TGF-β) signaling inhibits cell proliferation by inducing a G1 cell cycle arrest. By contrast, cyclin-dependent kinase 4 (CDK4) inactivates retinoblastoma function early in G1, thus promoting cell cycle progression. However, CDK4 can also inhibit TGF-β signaling by phosphorylating the linker region of Smad3, a key mediator of TGF-β signaling. We have previously demonstrated that Smad3 nuclear translocation and TGF-β signaling are dependent upon the function of the adaptor protein, beta-2 spectrin (β2SP or ELF). Furthermore, loss of β2SP in a knockout model results in the spontaneous development of hepatocellular cancer (HCC). HCCs from these elf+/− mice overexpress CDK4, and haploinsufficiency of CDK4 in elf+/−/CDK4neo/+ mice suppresses hepatocarcinogenesis. These findings point towards competing activities of β2SP and CDK4 on TGF-β signaling, which may be determined by their modulation of Smad3. Our goal was to determine the mechanisms for these competing effects. Methods: We have overexpressed CDK4, β2SP, or both in human HCC cell lines. Using these stable cell lines, we examined Smad3 phosphorylation by western blot, Smad3 nuclear localization by immunocytochemistry, and TGF-β-regulated gene expression by quantitative RT-PCR (qPCR). Results: We sought to determine whether β2SP can rescue the CDK4-mediated suppression of TGF-β signaling. Over-expression of CDK4 blocked TGF-β-induced Smad3 nuclear translocation, whereas a CDK4/6-specific inhibitor, PD-0332991 (Pfizer, Inc) rescued Smad3 nuclear translocation. Similarly, over-expression of β2SP rescued Smad3 nuclear translocation in these CDK4 overexpressing cells. Furthermore, both PD-0332991 and β2SP overexpression enhanced the expression of TGF-β-regulated genes, as determined by qPCR. We hypothesize that the opposing effects of CDK4 and β2SP are mediated by the balance between the CDK4-mediated phosphorylation of the Smad3 linker region, and the β2SP-mediated phosphorylation of the Smad3 C-terminal domain. Thus, we also examined the domain-specific phosphorylation of Smad3 in CDK4-overexpressing cells. PD-0332991 specifically reduces phosphorylation of the linker region of Smad3 (T179 and S208), but has no effect on c-terminal phosphorylation (S423/S425), while overexpression of β2SP increases c-terminal phosphorylation. Assessment of Smad3 nuclear localization and the effects on TGF-β signaling in the presence of phospho-specific Smad3 mutants is ongoing. Conclusions: Our results have begun to clarify the competing roles of CDK4 and β2SP on Smad3 nuclear localization and thus TGF-β signaling. Based on our results, targeted-inhibition of the CDK4-Smad3 interaction may be critical in rescuing TGF-β-mediated regulation of cell cycle control, but β2SP expression may be required, and may serve as a critical marker predictive of such activity. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3884.

Identification of stemonamide synthetic intermediates as a novel potent anticancer drug with an apoptosis‐inducing ability

We previously demonstrated that Pim-3, a protooncogene with serine/threonine kinase activity, was aberrantly expressed in malignant lesions but not in normal tissues of endoderm-derived organs, including pancreas, liver, colon and stomach. Moreover, aberrantly expressed Pim-3 can prevent tumor cell apoptosis by inactivating a proapoptotic molecule, Bad, and enhancing the expression of an antiapoptotic molecule, Bcl-X(L). These observations prompted us to speculate that a chemical targeting Pim-3 kinase may be a good candidate for a novel type of anticancer drug. Hence, we screened various low-molecule compounds by examining their capacity to inhibit Pim-3 kinase activity in vitro. We observed that some synthetic intermediates of stemonamide can inhibit in vitro activities of Pim-3 kinase and its related kinases, such as Pim-1 and Pim-2. Moreover, these compounds inhibit in vitro cell proliferation of various human pancreatic, hepatocellular and colon cancer cell lines. Furthermore, the compounds can induce apoptosis of human pancreatic cancer cell lines in vitro by reducing the amount of phospho-Ser(112)-Bad, but not total amounts of Bad and Pim-3. Finally, when the compound was administered to nude mice injected with a human pancreatic cancer cell line, it retarded tumor growth by increasing apoptotic cell numbers and decreasing proliferating cell numbers without causing serious adverse effects on blood counts. These observations indicate that the chemicals and its related compounds may be effective for the treatment of tumors of endoderm-derived organs, particularly the pancreas.

Garcinol inhibits cell growth in hepatocellular carcinoma Hep3B cells through induction of ROS-dependent apoptosis

Garcinol, derived from Garcinia indica and other related species, has been found to modulate several cell signalling pathways involved in apoptosis and cancer development. Growth arrest and DNA damage-inducible gene 153 (GADD153) is a member of the CCAAT/enhancer-binding protein (C/EBP) family of transcription factors; it is expressed at low levels under normal conditions but strongly induced upon growth arrest, DNA damage, and endoplasmic reticulum (ER) stress. This study investigated the effect of garcinol on Hep3B cells, a human hepatocellular cancer cell line lacking functional p53, with the goal of elucidating the molecular mechanisms of p53-independent apoptosis in hepatocellular cancer. Overall, garcinol activated not only the death receptor and the mitochondrial apoptosis pathways but also the ER stress modulator GADD153. Garcinol treatment led to the accumulation of reactive oxygen species (ROS), increased GADD153 expression, and reduced mitochondrial membrane potential. An increase in the Bax/Bcl-2 ratio resulted in enhanced apoptosis. Caspase-8 and tBid (truncated Bid) expression also increased in a time-dependent manner. The enzymatic activities of caspase-3 and caspase-9 increased approximately 13-fold and 7.8-fold, respectively. In addition, the proteolytic cleavage of poly-(ADP-ribose)-polymerase (PARP) and DNA fragmentation factor-45 (DFF-45) increased in dose- and time-dependent manners. Our data suggest a promising therapeutic application of garcinol in p53-independent apoptosis in cancers.

Design, synthesis and biological activity of cell‐penetrating peptide‐modified octreotide analogs

Four novel octreotide analogs with cell-penetrating peptides (CPPs) at the N-terminus or C-terminus were synthesized by a stepwise Fmoc solid-phase synthesis strategy. The synthesized peptides were analyzed and characterized using reverse phase HPLC and MALDI-TOF mass spectrometry. The antiproliferative activity of the analogs was tested in vitro on human gastric (SGC-7901) and hepatocellular cancer (BEL7402) cell lines using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Interestingly, these analogs showed a higher anticancer activities than the parent octreotide except CMTPT03 analog. The results demonstrate that the designed octreotide analogs enhance their anticancer activity after linking together the CPPs to octreotide at the N-terminus, and are potential molecules for future use in cancer therapy and drug targeting.

Serotonin promotes tumor growth in human hepatocellular cancer†

In addition to its function as a neurotransmitter and vascular active molecule, serotonin is also a mitogen for hepatocytes and promotes liver regeneration. A possible role in hepatocellular cancer has not yet been investigated. Human hepatocellular cancer cell lines Huh7 and HepG2 were used to assess the function of serotonin in these cell lines. Characteristics of autophagy were detected with transmission electron microscopy, immunoblots of microtubule-associated protein light chain 3(LC3) and p62 (sequestosome 1). Immunoblots of the mammalian target of rapamycin (mTOR) and its downstream targets p70S6K and 4E-BP1 were used to investigate signaling pathways of serotonin. Two different animal models served as principle of proof of in vitro findings. Clinical relevance of the experimental findings was evaluated with a tissue microarray from 168 patients with hepatocellular carcinoma. Serotonin promotes tumor growth and survival in starved hepatocellular carcinoma cells. During starvation hepatocellular carcinoma cells exhibited characteristics of autophagy, which disappeared in serotonin-treated cells. Rapamycin, an inhibitor of mTOR, is known to induce autophagy. Serotonin could override rapamycin by an mTOR-independent pathway and activate common downstream signals such as p70S6K and 4E-BP1. In two tumor models of the mouse, inhibition of serotonin signaling consistently impaired tumor growth. Human biopsies revealed expression of the serotonin receptor HTR2B, correlating with downstream signals, e.g., phosphorylated p70S6K and proliferation. This study provides evidence that serotonin is involved in tumor growth of hepatocellular cancer by activating downstream targets of mTOR, and therefore serotonin-related pathways might represent a new treatment strategy.

Effect of Low-Dose Rapamycin on Tumor Growth in Two Human Hepatocellular Cancer Cell Lines

Aim Liver transplantation is the best treatment for patients with early hepatocellular carcinoma (HCC) and cirrhosis. A limiting factor for long-term survival remains posttransplant tumor recurrence. Thus, there is widespread discussion about the role of various immunosuppressive agents. The newly developed immunosuppressive drug rapamycin may aid to lower recurrence rates. We investigated the efficiency of rapamycin as compared with previous immunosuppressants in a tumor cell model. Methods We studied two HCC cell lines for cell-cycle and proliferation analyses after treatment with rapamycin or other immunosuppressants. To elucidate the underlying molecular signaling pathway, we performed Western blotting for phosphorylated p70 S6 kinase protein expression. Results Low-dose rapamycin inhibited tumor cell growth at doses of 1, 5, and 10 ng/mL, while standard immunosuppressants stimulated growth. A rapamycin dose of 20 ng/mL showed a marked decrease in the growth inhibition of both HCC cell lines compared to low-dose administration. Conclusion Rapamycin in low doses inhibited the growth of two HCC cell lines in vitro. Inhibition of tumor cell growth was observed with a high dose of rapamycin (20 ng/mL), which appears to be the dividing line between growth and inhibition. We postulated that at higher doses the immunosuppressive effect of rapamycin is overrode by its antitumor effects.

Combined anti-tumor effects of mDRA-6 and nimesulide on human hepatocellular cancer cell line SMMC-7721

The aim of this work was to evaluate anti-tumor effects of mDRA-6 plus nimesulide on a human hepatocellular cancer cell line, SMMC-7721, and study the main mechanisms. The DR5 receptor of SMMC-7721 cells was detected by flow cytometry (FCM). For further experimental application, SMMC-7721 cells were treated with proper dose of mDRA-6, nimesulide, or mDRA-6 plus 200 μmol/L nimesulide; untreated SMMC-7721 cells were comparably set as control. Cytotoxicity was tested by MTT assay; cell morphology was examined using Hoechst 33258 staining; and apoptosis was determined by FCM. The positive rate of DR5 on SMMC-7721 was 95.0%. Either mDRA-6 or nimesulide alone induces SMMC-7721 cell death in a dose-dependent manner. Treatment of 1,600 ng/mL mDRA-6 for 12h led to a cell-death rate of 35.0%, while an increased cell-death rate (91.1%) was found under the same condition of mDRA-6 treatment supplemented with 200 μmol/L nimesulide. Hoechst 33258 and Annexin V/PI staining confirmed apoptosis as the main cause of this anti-tumor response. Both mDRA-6 and nimesulide can induce apoptosis of SMMC-7721 cells, and they have synergistic anti-tumor activities against SMMC-7721.

Synthesis and biological evaluation of novel 2,4,5-substituted pyrimidine derivatives for anticancer activity

A series of novel 2,4,5-substituted pyrimidine derivatives were synthesized and evaluated for inhibition against the human hepatocellular carcinoma BEL-7402 cancer cell line. Several compounds showed potent inhibition with an IC 50 value less than 0.10 μM. Structure–activity relationships for this class of compounds at the 2- and 5-position of the pyrimidine scaffold have been elucidated. The most active compound 7gc showed good inhibition of several different human cancer cell lines with IC 50 values from 0.024 to 0.55 μM.

The Effect of Doxorubicin on MEK-ERK Signaling Predicts Its Efficacy in HCC

Hepatocellular cancer (HCC) is a leading cause of cancer-related death worldwide. Historically, doxorubicin (DOX) has been widely used against unresectable HCC with variable response rates. We hypothesized that DOX combined with mitogen-activated protein kinase kinase-extracellular signal-regulated kinase (MEK-ERK) targeted therapy may provide enhanced anti-cancer effects. Human HCC cell lines (HepG2, Hep3B) were treated with DOX and MEK enzyme inhibitors, U0126 or PD184161, alone or in combination. Growth, apoptosis, and ERK expression/MEK activity were respectively determined by proliferation assay, DNA fragmentation enzyme-linked immunoassay or fluorochrome inhibitor of caspases, and Western blot. DOX (0.01-1 microM) decreased cell proliferation in Hep3B cells (IC(50) approximately 0.12 microM) at 48 to 72 h; DOX was less effective in HepG2 cells (IC(50) approximately 0.25 microM). At early time points (30 min) after DOX treatment of Hep3B cells, MEK activity was unchanged at low doses and decreased at higher doses; after 24 h, phospho-ERK levels increased at higher doses. Contrarily, in HepG2 cells, DOX caused a sustained, dose-dependent increase in phospho-ERK levels at early and late time points. The MEK inhibitor U0126 decreased phospho-ERK in both HCC lines. In contrast to DOX, HepG2 cells were more sensitive than Hep3B cells to U0126. The combination of DOX with U0126 (or PD184161) resulted in greater inhibition of proliferation in HepG2 but not in Hep3B cells. This effect may be mediated in part by enhanced apoptosis. The effect of DOX on early and late induction of MEK activity predicts its chemotherapeutic response in HCC. Furthermore, this effect may also determine the utility of MEK inhibitor combination treatment.

Disruption of transforming growth factor-β signaling through β-spectrin ELF leads to hepatocellular cancer through cyclin D1 activation

Transforming growth factor-beta (TGF-beta) signaling members, TGF-beta receptor type II (TBRII), Smad2, Smad4 and Smad adaptor, embryonic liver fodrin (ELF), are prominent tumor suppressors in gastrointestinal cancers. Here, we show that 40% of elf(+/-) mice spontaneously develop hepatocellular cancer (HCC) with markedly increased cyclin D1, cyclin-dependent kinase 4 (Cdk4), c-Myc and MDM2 expression. Reduced ELF but not TBRII, or Smad4 was observed in 8 of 9 human HCCs (P<0.017). ELF and TBRII are also markedly decreased in human HCC cell lines SNU-398 and SNU-475. Restoration of ELF and TBRII in SNU-398 cells markedly decreases cyclin D1 as well as hyperphosphorylated-retinoblastoma (hyperphosphorylated-pRb). Thus, we show that TGF-beta signaling and Smad adaptor ELF suppress human hepatocarcinogenesis, potentially through cyclin D1 deregulation. Loss of ELF could serve as a primary event in progression toward a fully transformed phenotype and could hold promise for new therapeutic approaches in human HCCs.

MicroRNA-21 Regulates Expression of the PTEN Tumor Suppressor Gene in Human Hepatocellular Cancer

microRNAs (miRNAs) are short noncoding RNAs that regulate gene expression negatively. Although a role for aberrant miRNA expression in cancer has been postulated, the pathophysiologic role and relevance of aberrantly expressed miRNA to tumor biology has not been established. We evaluated the expression of miRNA in human hepatocellular cancer (HCC) by expression profiling, and defined a target gene and biologically functional effect of an up-regulated miRNA. miR-21 was noted to be highly overexpressed in HCC tumors and cell lines in expression profiling studies using a miRNA microarray. Inhibition of miR-21 in cultured HCC cells increased expression of the phosphatase and tensin homolog (PTEN) tumor suppressor, and decreased tumor cell proliferation, migration, and invasion. In contrast-enhanced miR-21 expression by transfection with precursor miR-21 increased tumor cell proliferation, migration, and invasion. Moreover, an increase in cell migration was observed in normal human hepatocytes transfected with precursor miR-21. PTEN was shown to be a direct target of miR-21, and to contribute to miR-21 effects on cell invasion. Modulation of miR-21 altered focal adhesion kinase phosphorylation and expression of matrix metalloproteases 2 and 9, both downstream mediators of PTEN involved in cell migration and invasion. Aberrant expression of miR-21 can contribute to HCC growth and spread by modulating PTEN expression and PTEN-dependent pathways involved in mediating phenotypic characteristics of cancer cells such as cell growth, migration, and invasion.

TGF-beta signaling pathway inactivation and cell cycle deregulation in human hepatocellular cancer cell lines and elf+/− tissues

TGF-beta signaling pathway inactivation and cell cycle deregulation in human hepatocellular cancer cell lines and elf+/− tissues

Anticancer activity of a series of platinum complexes integrating demethylcantharidin with isomers of 1,2-diaminocyclohexane

A series of platinum complexes derived from integrating demethylcantharidin (DMC) with different isomers of 1,2-diaminocyclohexane (DACH) has been synthesized and found to exhibit superior in vitro anticancer activity against colorectal and human hepatocellular cancer cell lines when compared with oxaliplatin, cisplatin, and carboplatin. Flow cytometric analysis revealed that the trans-DACH–Pt–DMC analogues showed similar behavior to oxaliplatin on affecting the cell cycle of the HCT116 colorectal cancer cell line, but distinct from that of cisplatin or carboplatin. The DACH component apparently dictates the trans-DACH–Pt–DMC complexes to behave mechanistically similar to oxaliplatin, whereas the DMC ligand appears to enhance the compounds’ overall anticancer activity, probably by accelerating the cell cycle from G1 to S-phase with subsequent onset of G2/M arrest and accompanying apoptosis.

Arsenic trioxide inhibits DNA methyltransferase and restores methylation-silenced genes in human liver cancer cells

In the present study, we investigated methylation status of the CpG islands of some major tumor suppressor genes both in human hepatocellular carcinoma and liver cancer cell lines and examined whether demethylation by arsenic trioxide (As2O3) could restore their expression in the cell lines. HepG2 and Huh-7 cells were treated with 2 to 10 micromol/L of AS2O3 and/or 1 micromol/L of 5-aza-2'-deoxycytidine for 24, 48, and 72 hours. The methylation status of the CpG island around the promoter regions of p161NK4a, RASSF1A, E cadherin, and GSTP1 was detected by a methylation-specific polymerase chain reaction (MSP). The messenger RNA (mRNA) and protein levels of these genes were determined by quantitative real-time reverse transcriptase-polymerase chain reaction, Western blot, and immunohistochemical analyses. The DNA methyltransferase (DNMT) mRNA levels and enzyme activity were also examined. The hypermethylated status of the promoter regions of p16INK4a, RASSF1A, E cadherin, and GSTP1 was observed in 10 (40%), 14 (56%), 6 (24%), and 12 (48%) of 25 patients with hepatocellular carcinoma, respectively. CpG methylation of the p16INK4a, RASSF1A, E cadherin, and GSTP1 genes was correlated to the reduction of mRNA levels in the cell lines, and mRNA expression of these 4 genes were indeed restored by low concentrations (2-6 micromol/L) of As2O3 through demethylation, as well as 1 micromol/L of 5-aza-2'-deoxycytidine. Western blot and immunohistochemical analyses confirmed that each protein was markedly enhanced after treatment with a low concentration of As2O3. In contrast, As2O3 at a high concentration (10 micromol/L) damaged cell membranes and remarkably suppressed these 4 protein levels. As2O3 decreased the mRNA expression of DNMT 1 and also dose-dependently inhibited DNMT activity. In conclusion, a low concentration of As2O3 induces CpG island demethylation of tumor suppressor genes by inhibition of DNMT and reactivates the partially/fully silenced genes in liver cancer cells.

Cycloprodigiosin hydrochloride, a new H(+)/Cl(-) symporter, induces apoptosis in human and rat hepatocellular cancer cell lines in vitro and inhibits the growth of hepatocellular carcinoma xenografts in nude mice.

The effects of cycloprodigiosin hydrochloride (cPrG-HCl), a new H(+)/Cl(-) symporter, were examined in liver cancer cell lines in vitro and in vivo. In the in vitro MTT assay, cPrG-HCl inhibited the growth of 6 liver cancer cell lines (Huh-7, HCC-M, HCC-T, dRLh-84, and H-35, hepatocellular carcinoma; HepG2, hepatoblastoma) in a dose- and time-dependent manner. The 50% inhibitory concentrations (IC(50)) at 72 hours' treatment for liver cancer cell lines were 276 to 592 nmol/L, while that for isolated normal rat hepatocyte was 8.4 micromol/L. The cPrG-HCl treatment of Huh-7 cells induced apoptosis as confirmed by the appearance of a subG(1) population, intranucleosomal DNA fragmentation, and chromatin condensation. cPrG-HCl raised the pH of acidic organelles and lowered pHi (below pH 6.8). In addition, the apoptosis in Huh-7 cells induced by cPrG-HCl was strongly suppressed when the cells were cultured with imidazole, a cell-permeable base. In the in vivo assay, nude mice bearing subcutaneous xenografted Huh-7 cells received 2 weeks of treatment with cPrG-HCl (1 or 10 mg/kg/d) subcutaneously. This treatment significantly inhibited tumor growth compared with the control after 8 days. The control mice were treated with 1% dimethylsulfoxide (DMSO) in saline (vehicle). A histopathological examination using the terminal deoxynucleotidyl transferase mediated dUTP biotin nick end labeling (TUNEL) method showed apoptosis in the treated tumor cells. No pathological changes were observed in any organs, and the serum alanine transaminase levels remained within normal limits. These results suggest that cPrG-HCl may be useful for the treatment of hepatocellular carcinoma.