benzyloxycarbonylvalyl-alanyl-aspartyl-fluoromethyl-ketone and Liver-Neoplasms

Decreasing hepatocyte injury and death is an attractive therapeutic target in chronic hepatitis C and other liver diseases. Apoptotic cell death is a critical mechanism responsible for liver injury in hepatitis C, and contributes to hepatic fibrogenesis. At the cellular level, apoptosis is executed by a family of cysteine proteases termed caspases. Caspase inhibitors have been developed to inhibit these proteases and attenuate cellular apoptosis in vivo. By reducing hepatocyte apoptosis these agents have the potential to serve as hepatoprotective agents, minimizing liver injury and fibrosis. Studies on a variety of animal models, and time-limited studies in human patients with hepatitis C suggest these are promising therapeutic agents. However, although these agents hold promise, their usefulness requires further studies, especially longer duration studies using hepatic fibrogenesis as the end point before they can be considered further for the treatment of patients infected with the hepatitis C virus.

Topics: Amino Acid Chloromethyl Ketones; Antiviral Agents; Apoptosis; Caspase Inhibitors; Cysteine Proteinase Inhibitors; Hepacivirus; Hepatitis C, Chronic; Humans; Liver Neoplasms

HCC is a highly lethal malignancy with Sorafenib as the only molecularly targeted drug. The multifunctional stress-associated protein, NUPR1, plays an essential role in controlling cell growth, migration, invasion and Sorafenib resistance in HCC. We report here that NUPR1 expression is absent in healthy liver and it is progressively upregulated in HCC premalignant lesions such as hepatitis and cirrhosis with a maximum expression in HCC samples, highlighting that NUPR1 is a potential drug target for HCC. We therefore assessed in this work, ZZW-115, a strong inhibitor of NUPR1, as a promising candidate for the treatment of HCC. We validated its extraordinary antitumor effect on HCC by using two HCC cell lines, HepG2-and Hep3B, both in cell based experiments and xenografted mice. We further revealed that ZZW-115 treatment induced cell death by apoptosis and necroptosis mechanisms, with a concomitant mitochondrial metabolism failure that triggers lower ATP production. Furthermore, the ATP depletion cannot be rescued by the apoptosis inhibitor Z-VAD-FMK and/or the necrosis inhibitor Necrostatin-1, indicating that ZZW-115 induces cell death through the mitochondrial failure.

Topics: Adenosine Triphosphate; Adult; Aged; Amino Acid Chloromethyl Ketones; Animals; Apoptosis; Basic Helix-Loop-Helix Transcription Factors; Carcinoma, Hepatocellular; Cell Line, Tumor; Female; Humans; Liver Neoplasms; Male; Mice; Mice, Inbred BALB C; Middle Aged; Mitochondria; Neoplasm Proteins; Piperazines; Thiazines

Juglone (JG), a naturally-occurring naphthoquinone of Manchurian walnut (Juglans mandshurica) was shown to inhibit proliferation in various tumor types. However, the molecular mechanisms of JG on the induction of apoptosis and autophagy in HepG2 cells have not been examined. Herein, we investigated that JG could inhibit cell proliferation by induction of G2/M phase arrest. Also, occurrence of apoptosis was closely related with loss of mitochondrial membrane potential, the changes of apoptosis-related proteins after treatment with JG. In addition, we found that JG caused autophagy, as evidenced by increased expressions of LC3-II and Beclin-1. Interestingly, inhibition of JG-induced autophagy by 3-methyladenine (3-MA) and wortmannin (WT) significantly decreased apoptosis, whereas the apoptosis inhibitor z-VAD-fmk slightly enhanced autophagy. Furthermore, the induction of autophagy and apoptosis was associated with activation of MAPK family members (p38 and JNK) and production of reactive oxygen species (ROS). Both JNK inhibitor (SP600125) and ROS scavenger (N-acetylcysteine, NAC) could attenuate JG-induced autophagy and apoptosis. However, the p38-specific inhibitor SB203580 enhanced autophagic and apoptotic death. Moreover, the ROS scavenger NAC prevented phosphorylation of both p38 and JNK. Collectively, our data revealed that JG induced G2/M phase arrest, apoptosis, and autophagy through the ROS-dependent signaling pathway.

Topics: Acetylcysteine; Adenine; Amino Acid Chloromethyl Ketones; Androstadienes; Apoptosis; Autophagy; Carcinoma, Hepatocellular; Cell Cycle Checkpoints; Cell Proliferation; Enzyme Activation; Hep G2 Cells; Humans; Liver Neoplasms; MAP Kinase Kinase 4; MAP Kinase Signaling System; Membrane Potential, Mitochondrial; Naphthoquinones; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Reactive Oxygen Species; Wortmannin

Inhibition of proteasome-associated deubiquitinases (DUBs) is emerging as a novel strategy for cancer therapy. It was recently reported that auranofin (Aur), a gold (I)-containing compound used clinically to treat rheumatoid arthritis, is a proteasome-associated DUB inhibitor. Disulfiram (DSF), an inhibitor of aldehyde dehydrogenase, is currently in clinical use for treating alcoholism. Recent studies have indicated that DSF can also act as an antitumor agent. We investigated the effect of combining DSF and Aur on apoptosis induction and tumor growth in hepatoma cancer cells. Here we report that (i) the combined treatment of Aur and DSF results in synergistic cytotoxicity to hepatoma cells in vitro and in vivo; (ii) Aur and DSF in combination induces caspase activation, endoplasmic reticulum (ER) stress, and reactive oxygen species (ROS) production; (iii) pan-caspase inhibitor z-VAD-FMK could efficiently block apoptosis but not proteasome inhibition induced by Aur and DSF combined treatment, and ROS is not required for Aur+DSF to induce apoptosis. Collectively, we demonstrate a model of synergism between DSF and proteasome-associated DUB inhibitor Aur in the induction of apoptosis in hepatoma cancer cells, identifying a potential novel anticancer strategy for clinical use in the future.

Topics: Aldehyde Dehydrogenase; Amino Acid Chloromethyl Ketones; Animals; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Auranofin; Carcinoma, Hepatocellular; Caspase Inhibitors; Caspases; Cell Line, Tumor; Cell Survival; Disulfiram; Drug Synergism; Endoplasmic Reticulum Stress; Enzyme Activation; Hep G2 Cells; Humans; Liver Neoplasms; Mice; Mice, Nude; Poly(ADP-ribose) Polymerases; Reactive Oxygen Species; Ubiquitin-Specific Proteases; Xenograft Model Antitumor Assays

Hepatocellular carcinoma (HCC) is the fifth most common cancer in the world. The aim of radiotherapy is to eradicate cancer cells with ionizing radiation. Except for the caspase-dependent mechanism, several lines of evidence demonstrated that caspase-independent mechanism is directly involved in the cell death responding to irradiation. For this reason, defining the contribution of caspase-independent molecular mechanisms represents the main goal in radiotherapy. In this study, we focused on the role of apoptosis-inducing factor (AIF), the caspase-independent molecular, in ionizing radiation induced hepatocellular carcinoma cell line (HepG2) cell death. We found that ionizing radiation has no function on AIF expression in HepG2 cells, but could induce AIF release from the mitochondria and translocate into nuclei. Inhibition of AIF could reduce ionizing radiation induced HepG2 cell death. These studies strongly support a direct relationship between AIF nuclear translocation and radiation induced cell death. What's more, AIF nuclear translocation is caspase-independent manner, but not caspase-dependent manner, in this process. These new findings add a further attractive point of investigation to better define the complex interplay between caspase-independent cell death and radiation therapy.

Topics: Active Transport, Cell Nucleus; Amino Acid Chloromethyl Ketones; Apoptosis Inducing Factor; Carcinoma, Hepatocellular; Caspase Inhibitors; Caspases; Cell Death; Dose-Response Relationship, Radiation; Hep G2 Cells; Humans; Liver Neoplasms; RNA, Small Interfering

Cordycepol C, a novel sesquiterpene isolated from the cultured mycelia of Cordyceps ophioglossoides, contains a hydroperoxy group and is cytotoxic to HepG2 cells. So far, no sesquiterpenes have been found in the genus Cordyceps and it would be interesting to investigate the antitumor efficacy as well as the mechanism of action of this unusual sesquiterpene. In this study, we showed that cordycepol C induced apoptosis of the HepG2 cells without affecting the normal liver cell line L-02. Cordycepol C caused poly(ADP-ribose)polymerase-1 (PARP-1) cleavage and triggered the loss of mitochondrial membrane potential (Δψm) in HepG2 cells in a time- and dose-dependent manner, resulting in the nuclear translocation of apoptosis-inducing factor (AIF) and endonuclease G (Endo G). We also found that cordycepol C induced the expression of Bax protein, followed by its translocation from the cytosol to mitochondria in both wild type and p53 knockdown HepG2 cells. However, cordycepol C could not cause cleavages of procaspase-3, -8, and -9. Caspase activities were not increased and Z-VAD-fmk, a caspase inhibitor, could not prevent the apoptosis induced by cordycepol C. These findings indicate that cordycepol C induces caspase-independent apoptosis in HepG2 cells through a p53-independent and Bax-mediated mitochondrial pathway, leading to the nuclear translocation of AIF and Endo G. Our study provides the molecular mechanism by which cordycepol C induces apoptosis in hepatocellular carcinoma cells and indicates the potential use of cordycepol C as an antitumor agent.

Topics: Amino Acid Chloromethyl Ketones; Antineoplastic Agents; Apoptosis; Apoptosis Inducing Factor; bcl-2-Associated X Protein; Carcinoma, Hepatocellular; Caspase 3; Caspase 9; Caspase Inhibitors; Caspases; Cell Line; Endodeoxyribonucleases; Gene Knockdown Techniques; Hep G2 Cells; Humans; Liver Neoplasms; Membrane Potential, Mitochondrial; Poly(ADP-ribose) Polymerases; Sesquiterpenes; Tumor Suppressor Protein p53

Nü-zhen-zi, the fruit of Ligustrum lucidum Ait., is one of the most frequently used liver Yin tonifying Chinese herbs for the treatment of liver cancer. However, the effect of Ligustrum lucidum fruit on hepatocarcinoma cells remains unknown. In the present study, we evaluated the effects of a Ligustrum lucidum fruit extract (LLFE) on human hepatocellular carcinoma Bel-7402 cells. The results showed that LLFE inhibited the proliferation of the Bel-7402 cells in a dose- and time-dependent manner. LLFE induced apoptosis in Bel-7402 cells accompanied by activation of caspase-3, -8 and -9. LLFE-induced apoptosis was completely abrogated by a pan caspase inhibitor, Z-VAD-FMK. LLFE treatment also caused a large and flat morphologic cellular change, positive SA-β-gal staining, and G0/G1 phase cell cycle arrest in the Bel-7402 cells, accompanied by upregulation of p21 and downregulation of RB phosphorylation. Specific knockdown of p21 expression by RNA interference partially abrogated LLFE-induced apoptosis, and significantly abrogated LLFE-induced cell senescence. These observations suggest that Nü-zhen-zi is a potential anticancer herb and support the traditional use of Nü-zhen-zi for hepatocarcinoma treatment.

Topics: Amino Acid Chloromethyl Ketones; Antineoplastic Agents; Apoptosis; Carcinoma, Hepatocellular; Caspase Inhibitors; Caspases; Cell Line, Tumor; Cell Proliferation; Cyclin-Dependent Kinase Inhibitor p21; Humans; Ligustrum; Liver Neoplasms; Plant Extracts

Rosin, the traditional Chinese medicine, is reported to be able to inhibit skin cancer cell lines. In this report, we investigate the inhibitory effect against HCC cells of QC2, the derivative of rosin's main components dehydroabietic acid.. MTT assay was used to determine the cytotoxicity of QC2. Morphological changes were observed by time-lapse microscopy and transmission electron microscopy and the cytoskeleton changes were observed by laser-scanning confocal microscopy. Cytomembrane integrity and organelles damage were confirmed by detection of the reactive oxygen (ROS), lactate dehydrogenase (LDH), and mitochondrial membrane potential (Δψm). The underlying mechanism was manifested by Western blotting. The oncotic cell death was further confirmed by detection of oncosis related protein calpain.. Swelling cell type and destroyed cytoskeleton were observed in QC2-treated HCC cells. Organelle damage was visualized by transmission electron microscopy. The detection of ROS accumulation, increased LDH release, and decreased ATP and Δψm confirmed the cell death. The oncotic related protein calpain was found to increase time-dependently in QC2-treated HCC cells, while its inhibitor PD150606 attenuated the cytotoxicity.. Dehydroabietic acid derivative QC2 activated oncosis related protein calpain to induce the damage of cytomembrane and organelles which finally lead to oncosis in HCC cells.

Topics: Abietanes; Adenosine Triphosphate; Amino Acid Chloromethyl Ketones; Calpain; Carcinoma, Hepatocellular; Caspase 3; Caspase Inhibitors; Cell Death; Cell Line, Tumor; Cell Membrane; Cytoskeleton; Hepatocytes; Humans; Imidazoles; Indoles; Liver Neoplasms; Membrane Potential, Mitochondrial; Reactive Oxygen Species

Klotho has been identified as a tumor suppressor in several human malignancies including hepatocellular carcinoma (HCC). However, the signaling pathways involved in the tumor suppressive role of klotho in HCC have not been reported. Here, we investigated the role of klotho in HCC cell proliferation, apoptosis, autophagy, and invasion, as well as its associated signal transduction pathways.. Restoration of klotho gene expression was established by delivering a klotho gene expression vector into the human HCC cell lines HepG2 and MHCC-97-H. Cell viability was measured using a cell counting (CCK-8) assay and apoptosis was analyzed through flow cytometry. Autophagy was measured via LC3-I and LC3-II protein expression levels and tumor cell invasion was assessed using a Matrigel invasion chamber assay. Expression and phosphorylation of several apoptosis and survival related proteins were assessed using Western blot assays.. Exogenous klotho gene expression significantly inhibited HCC cell proliferation, induced HCC cell apoptosis, increased LC3-I and LC3-II protein expression in HCC cells, and decreased migration of HCC cells in a Matrigel invasion chamber assay. Exogenous klotho gene expression also down-regulated the phosphorylation levels of the IGF-1 receptor, and the downstream Akt, ERK, and p70S6K proteins. Both apoptosis and autophagy inhibitors decreased klotho-induced apoptosis and autophagy.. Klotho is a tumor suppressor that, through the regulation of IGF-1R phosphorylation and subsequent activation of downstream Akt-p70S6K and ERK signaling, regulates HCC tumor cell proliferation, apoptosis, autophagy and invasion.

Topics: Adenine; Amino Acid Chloromethyl Ketones; Apoptosis; Autophagy; Blotting, Western; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Movement; Cell Survival; Extracellular Signal-Regulated MAP Kinases; Flow Cytometry; Gene Expression Regulation, Neoplastic; Glucuronidase; Hep G2 Cells; Humans; Klotho Proteins; Liver Neoplasms; Microtubule-Associated Proteins; Proto-Oncogene Proteins c-akt; Receptor, IGF Type 1; Reverse Transcriptase Polymerase Chain Reaction; Ribosomal Protein S6 Kinases, 70-kDa; Signal Transduction; Transfection

To investigate the role of polo-like kinase 1 (PLK1) as a therapeutic target for hepatocellular carcinoma (HCC).. PLK1 gene expression was evaluated in HCC tissue and HCC cell lines. Gene knockdown with short-interfering RNA (siRNA) was used to study PLK1 gene and protein expression using real-time reverse transcription polymerase chain reaction (RT-PCR) and Western blotting, and cell proliferation using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2(4-sulfophenyl)-2H-tetrazolium (MTS) and bromodeoxyuridine (BrdU) assays. Apoptosis was evaluated using the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, and caspase-inhibition assay. Huh-7 cells were transplanted into nude mice and co-cultured with PLK1 siRNA or control siRNA, and tumor progression was compared with controls.. RT-PCR showed that PLK1 was overexpressed 12-fold in tumor samples compared with controls, and also was overexpressed in Huh-7 cells. siRNA against PLK1 showed a reduction in PLK1 gene and protein expression of up to 96% in Huh-7 cells, and a reduction in cell proliferation by 68% and 92% in MTS and BrdU cell proliferation assays, respectively. There was a 3-fold increase in apoptosis events, and TUNEL staining and caspase-3 assays suggested that this was caspase-independent. The pan-caspase inhibitor Z-VAD-FMK was unable to rescue the apoptotic cells. Immnofluorescence co-localized endonuclease-G to fragmented chromosomes, implicating it in apoptosis. Huh-7 cells transplanted subcutaneously into nude mice showed tumor regression in siPLK1-treated mice, but not in controls.. Knockdown of PLK1 overexpression in HCC was shown to be a potential therapeutic target, leading to apoptosis through the endonuclease-G pathway.

Topics: Adult; Aged; Aged, 80 and over; Amino Acid Chloromethyl Ketones; Animals; Apoptosis; Blotting, Western; Carcinoma, Hepatocellular; Caspase 3; Caspase Inhibitors; Cell Cycle Proteins; Cell Proliferation; Endodeoxyribonucleases; Female; Fluorescent Antibody Technique; Gene Knockdown Techniques; Genetic Therapy; Hep G2 Cells; Humans; Liver Neoplasms; Male; Mice; Mice, Nude; Middle Aged; Polo-Like Kinase 1; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; Transfection; Tumor Burden; Xenograft Model Antitumor Assays

Garlic (Allium sativum) compounds have recently received increasing attention due to their cancer chemopreventive properties, and their anticancer activities are extensively reported in many cancer cell lines. However, the anticancer activity and the signaling pathway associated with the induction of apoptosis by extracts of garlic cloves have not been elucidated. In this study, we examined the effects of hexane extracts of garlic cloves (HEGCs) on reactive oxygen species (ROS) production and the association of these effects with apoptotic cell death, using a Hep3B human hepatocarcinoma cell line in vitro. The results demonstrated that HEGCs mediate ROS production, and that this mediation is followed by a collapse of mitochondrial membrane potential (MMP, ΔΨm), the downregulation of anti-apoptotic Bcl-2 and Bcl-xL and the activation of caspase-9 and -3. HEGCs also promoted the activation of caspase-8 and the downregulation of Bid, a BH3-only pro-apoptotic member of the Bcl-2. However, the apoptotic phenomena displayed by HEGCs were significantly diminished by the presence of z-VAD-fmk (non-selective caspase inhibitor). Moreover, N-acetyl-L-cysteine (NAC), a widely used ROS scavenger, effectively blocked the HEGC-induced apoptotic effects via the inhibition of ROS production and MMP collapse. These observations clearly indicate that HEGC-induced ROS are key mediators of MMP collapse, which leads to the induction of apoptosis, followed by caspase activation.

Topics: Acetylcysteine; Amino Acid Chloromethyl Ketones; Apoptosis; bcl-2 Homologous Antagonist-Killer Protein; bcl-2-Associated X Protein; BH3 Interacting Domain Death Agonist Protein; Carcinoma, Hepatocellular; Caspase 3; Caspase 8; Caspase 9; Caspase Inhibitors; Cell Line, Tumor; Cysteine Proteinase Inhibitors; Down-Regulation; Enzyme Activation; Free Radical Scavengers; Garlic; Humans; Liver Neoplasms; Membrane Potential, Mitochondrial; Mitochondria; Plant Extracts; Reactive Oxygen Species

2'-epi-2'-O-Acetylthevetin B (GHSC-74) is a cardiac glycoside isolated from the seeds of Cerbera manghas L. We have demonstrated that GHSC-74 reduced the viability of HepG2 cells in a time- and dose-dependent manner. The present study was designed to explore cellular mechanisms whereby GHSC-74 led to cell cycle arrest and apoptosis in HepG2 cells. Cell cycle flow cytometry demonstrated that HepG2 cells treated with GHSC-74 (4microM) resulted in S and G2 phase arrest in a time-dependent manner, as confirmed by mitotic index analysis. G2 phase arrest was accompanied with down-regulation of CDC2 and Cyclin B1 protein. Furthermore, GHSC-74-induced apoptotic killing, as demonstrated by DNA fragmentation, DAPI staining, and flow cytometric detection of sub-G1 DNA content in HepG2 cells. GHSC-74 treatment resulted in a significant increase in reactive oxygen species, activation of caspase-9, dissipation of mitochondrial membrane potential, and translocation of apoptosis-inducing factor (AIF) from the mitochondrion to the nucleus in HepG2 cells. Nevertheless, after GHSC-74 exposure, no significant Fas and FasL up-regulation was observed in HepG2 cells by flow cytometry. In addition, treatment with antioxidant N-acetyl-l-cysteine (NAC) and broad-spectrum caspase inhibitor z-VAD-fmk partially prevented apoptosis but did not abrogate GHSC-74-induced nuclear translocation of AIF. In conclusion, we have demonstrated that GHSC-74 inhibited growth of HepG2 cells by inducing S and G2 phase arrest of the cell cycle and by triggering apoptosis via mitochondrial disruption including both caspase-dependent and -independent pathways, and ROS generation.

Topics: Acetylcysteine; Amino Acid Chloromethyl Ketones; Antineoplastic Agents; Apocynaceae; Apoptosis; Apoptosis Inducing Factor; Carcinoma, Hepatocellular; Cardiac Glycosides; Caspase 9; CDC2 Protein Kinase; Cyclin B1; G2 Phase; Hep G2 Cells; Humans; Liver Neoplasms; Membrane Potential, Mitochondrial; Reactive Oxygen Species; S Phase; Seeds

Tanshinone IIA (Tan-IIA) is extracted from Danshen, Salviae miltiorrhizae Radix, which has been widely adopted in traditional herbal medicine to treat cardiovascular and hepatic diseases. Tan-IIA induces apoptosis and inhibits proliferation in human hepatocellular carcinoma (HCC) cells. However, the molecular mechanisms of Tan-IIA on human HCC cells are not understood clearly. In the present study, the cytotoxicity of Tan-IIA as well as its molecular mechanisms in human HCC J5 cells was investigated. The cytotoxicity was assayed by MTT. The protein expression of p53, p21, Bax, Bcl-2, Cdc25c, Cdc2, calreticulin, caspase 12, GADD153, caspase 3 and beta-actin in J5 cells were determined by Western blotting. The cell cycles were analyzed by FACS. The protein expression of caspase 12, GADD1533 and caspase 3 were detected by immunocytochemical staining. The results showed that Tan-IIA inhibited J5 cells in a dose- and time-dependent manner. The protein expression of p53, p21, Bax, calreticulin, caspase 12, caspase 3 and GADD153 were increased, but Bcl-2, Cdc25c and Cdc2 were decreased in J5 cells. In addition, the results also showed that Tan-IIA arrested J5 cells in the G2/M phase. Immunocytochemistry staining showed that J5 cells treated with Tan-IIA up-regulated the protein expression of caspase 12, 3 and GADD153. Taken together, the findings suggest that Tan-IIA inhibits and induces apoptosis in J5 cells through novel molecular targets, calreticulin, caspase 12 and GADD153.

Topics: Abietanes; Amino Acid Chloromethyl Ketones; Animals; Antineoplastic Agents, Phytogenic; Apoptosis; Calreticulin; Carcinoma, Hepatocellular; Caspase 12; Caspase Inhibitors; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cysteine Proteinase Inhibitors; Drugs, Chinese Herbal; Humans; Liver Neoplasms; Male; Mitochondria; Phenanthrenes; Transcription Factor CHOP

Peroxisome proliferators (PPs) are a class of compounds that exert their nominal effects through the peroxisome proliferator-activated receptors. PPs, among which clofibrate (CF), have been extensively studied for their hepatocarcinogenic properties in rodents, generally ascribed to their antiapoptotic action. However, previous results demonstrated that various PPs may also have apoptogenic properties. CF, in particular, promptly induces a massive apoptotic death in cell lines established from murine or human hepatomas and from breast or lung cancers as well. The present study was aimed at elucidating the apoptotic pathway(s) triggered by CF in AH-130 cells. The results show that CF-induced cell death is completely blocked by the poly-caspase inhibitor z-VAD-fmk and that caspases 3, 8, and 9 are early activated. Consistently, cytochrome c is released from mitochondria, and CF cytotoxicity is inhibited by cyclosporine A, partially at least. In addition, the occurrence of endoplasmic reticulum (ER) stress is suggested by the observation that the levels of phosphorylated eIF2alpha and JNK increase in CF-treated cells, while the caspase 2 precursor protein levels are concurrently reduced. Finally, some degree of calpain activation also takes place, as suggested by the appearance of fodrin cleavage products. The present findings demonstrate that CF-induced apoptosis in the Yoshida AH-130 cells basically is a caspase-dependent process that involves more than a single mechanisms. Activation of the intrinsic apoptotic pathway and ER stress both play a major and concurrent role, while calpain activation seems to have only a marginal part in the process.

Topics: Amino Acid Chloromethyl Ketones; Apoptosis; Carcinoma, Hepatocellular; Caspase 3; Caspase 8; Caspase 9; Cell Death; Cell Line, Tumor; Clofibrate; Cysteine Proteinase Inhibitors; Humans; Liver Neoplasms

Baicalein has been reported to induce growth-inhibitory activity in vitro in human cancer cells; however, the molecular mechanism of action is not completely understood. A pharmacological dose (10-100 microM) of baicalein exerted a cytotoxic effect on human hepatoma J5 cells resulting in G2/M arrest and apoptosis. In addition to cytotoxicity in J5 cells, several apoptotic events including mitochondrial cytochrome c release, activation of caspase-9 and -3 occurred. Baicalein induced AIF and Endo G release from mitochondria indicating that baicalein stimulates apoptosis through the caspase-independent pathway, while undergoing apoptosis, there was a remarkable accumulation of G2/M cells. Also, the ratio of Bax/Bcl-2 was increased leading to changes in mitochondria membrane potential (DeltaPsim) and release of cytochrome c, whereas the baicalein-induced apoptosis was partially abrogated by pretreatment with the pan-caspase inhibitor z-VAD-fmk, the accumulation of G2/M cells remained. These results demonstrate that the cytotoxicity of baicalein in J5 cells is attributable to apoptosis mainly involving G2/M-arrest in an ER-dependent manner, via a mitochondria-dependent caspase pathway and as well as contributions of AIF and Endo G pathways.

Topics: Amino Acid Chloromethyl Ketones; Antineoplastic Agents, Phytogenic; Apoptosis; Apoptosis Inducing Factor; bcl-2-Associated X Protein; Calcium; Carcinoma, Hepatocellular; Caspase 3; Caspase Inhibitors; Cell Cycle; Cell Line, Tumor; Cell Shape; Cell Survival; Cysteine Proteinase Inhibitors; Cytochromes c; DNA Damage; Dose-Response Relationship, Drug; Endodeoxyribonucleases; Enzyme Activation; Flavanones; Humans; Liver Neoplasms; Membrane Potential, Mitochondrial; Mitochondria; Proto-Oncogene Proteins c-bcl-2; Reactive Oxygen Species; Signal Transduction; Time Factors

The proteasome inhibitor bortezomib is an efficacious inducer of apoptosis in the hepatoma HepG2 cell line. This study shows that bortezomib increased in these cells the level of the survival factor Hsp72 in a time- and dose-dependent manner. In a first phase of treatment, Hsp72 rapidly increased so that at 24 h of incubation with 50 nM bortezomib its level was approximately five-fold higher than the control. In this phase Hsp72 seemed to play a role in preventing HepG2 cell death, since it interacted with and sequestered the pro-apoptotic factors p53, AIF, Bax and Apaf-1. During a second day of treatment, although the nuclear levels of Hsp72, p53 and AIF increased, the interaction of Hsp72 with these factors diminished. In addition, bortezomib induced the activation of caspases, which stimulated Hsp72 degradation. In conclusion, in the second day of treatment with bortezomib the protective ability of Hsp72 decreased thus favouring the appearance of apoptosis.

Topics: Amino Acid Chloromethyl Ketones; Apoptosis; Apoptosis Inducing Factor; Apoptosis Regulatory Proteins; Apoptotic Protease-Activating Factor 1; bcl-2-Associated X Protein; Blotting, Western; Boronic Acids; Bortezomib; Carcinoma, Hepatocellular; Cell Line, Tumor; HSP72 Heat-Shock Proteins; Humans; Immunoprecipitation; Liver Neoplasms; Protease Inhibitors; Protein Binding; Pyrazines; Reverse Transcriptase Polymerase Chain Reaction; Time Factors; Tumor Suppressor Protein p53

We have previously shown that transforming growth factor-beta(1) (TGF-beta(1))-induced apoptosis in FaO hepatoma cells is mediated by cytochrome c release, apoptosome formation, and caspase activation. Although TGF-beta(1) acts via the SMAD signaling pathway to initiate de novo gene transcription, little is known about the downstream gene targets that are involved in the regulation of apoptosis. Therefore, in this study, we used in-house microarrays (approximately 5500 genes) to identify pathway-specific gene clustering in TGF-beta(1)-treated cells. A total of 142 genes showed time-dependent changes in expression during TGF-beta(1)-induced apoptosis. The polycaspase inhibitor benzyloxycarbonyl-VAD-fluoromethyl ketone, which, on its own, had no effect on gene transcription, blocked TGF-beta(1)-induced cell death and significantly altered the expression of 261 genes, including 185 down-regulated genes. Cluster analysis identified up-regulation of early response genes (0-4 h) encoding for the extracellular matrix and cytoskeleton, including the pro-apoptotic CTGF gene, and delayed response genes (8-16 h), including pro-apoptotic genes. A second delayed response cluster (44 genes) was also observed when TGF-beta(1)-induced caspase activation was blocked by benzyloxycarbonyl-VAD-fluoromethyl ketone. This cluster included genes encoding stress-related proteins (e.g. Jun, ATF3, TAB1, and TANK), suggesting that their up-regulation may be in response to secondary necrosis. Finally, we identified an early response set of nine down-regulated genes that are involved in antioxidant defense. We propose that the regulation of these genes by TGF-beta(1) could provide a molecular mechanism for the observed elevation in reactive oxygen species after TGF-beta(1) treatment and may represent the primary mechanism through which TGF-beta(1) initiates apoptosis.

Topics: Amino Acid Chloromethyl Ketones; Annexin A5; Apoptosis; Base Sequence; Carcinoma, Hepatocellular; Enzyme Inhibitors; Gene Expression Regulation, Neoplastic; Humans; Liver Neoplasms; Multigene Family; Oligodeoxyribonucleotides, Antisense; Oligonucleotide Array Sequence Analysis; Reverse Transcriptase Polymerase Chain Reaction; Transcription, Genetic; Transforming Growth Factor beta; Tumor Cells, Cultured

15-deoxy-delta12,14-prostaglandin J2 (15-d-PGJ2) induces apoptosis in several carcinoma cell lines and is a potent activator of peroxisome proliferators-activated receptor-gamma (PPAR-gamma). In the present study, we examined the effect of 15-d-PGJ2 on human hepatoma cells.. HuH-7 and HepG2 cell lines were used in all the experiments. The mRNA expression of PPAR-gamma was studied by reverse transcriptase-polymerase chain reaction. The cell viability was determined by a modified MTT assay. Two methods were used for the determination of apoptosis in hepatoma cells: the TUNEL assay, and detection of fragmented mono- and oligo-nucleosomes by ELISA.. The expression of PPAR-gamma mRNA and protein was detected in HuH-7 and HepG2. Treatment with 15-d-PGJ2 decreased cell viability in a time- and dose-dependent manner. 15-d-PGJ2 induced apoptosis and this effect was time-dependent. Exposure of cells to 15-d-PGJ2 induced caspase-3 and -9 activation. Furthermore, co-treatment with the pan-caspase inhibitor Z-VAD-FMK or the caspase-3 inhibitor Z-DEVD-FMK blocked apoptosis of human hepatoma cells that had been treated with 15-d-PGJ2.. Our study demonstrates that PPAR-gamma is expressed in human hepatoma cell lines and that treatment with 15-d-PGJ2 inhibits the growth of these cells by inducing apoptosis through caspase activation.

Topics: Amino Acid Chloromethyl Ketones; Apoptosis; Carcinoma, Hepatocellular; Caspase Inhibitors; Caspases; Cell Line, Tumor; Cysteine Proteinase Inhibitors; Dose-Response Relationship, Drug; Enzyme-Linked Immunosorbent Assay; Humans; Immunologic Factors; In Situ Nick-End Labeling; Liver Neoplasms; Oligopeptides; Prostaglandin D2; Receptors, Cytoplasmic and Nuclear; Reverse Transcriptase Polymerase Chain Reaction; Transcription Factors

Ethanol is known to induce apoptosis in hepatocytes. However, intracellular signaling events of ethanol-induced death are still only partially understood. We studied such processes in ethanol-induced apoptosis in HepG2 cells as a model system for human liver cells. We determined the incidence of apoptosis by DNA fragmentation and tested the effects of various known inhibitors. Ethanol induces apoptosis in HepG2 cells in a dose- and time-dependent manner as well as in rat primary hepatocytes. This effect was not mediated through the death receptor CD95 and the tumor necrosis factor receptors. It was efficiently inhibited by the caspase inhibitor N-benzyloxycarbonyl-Asp-Glu-Val-Asp-fluoromethylketone (zVAD-fmk), the Ca(2+) chelator EGTA, and the serine protease inhibitor N-p-tosyl-l-lysine chloromethyl ketone (TLCK). Upon ethanol treatment, the intracellular calcium ion concentration was increased and cytochrome c was released from the mitochondria, and caspases were activated. EGTA and TLCK could inhibit cytochrome c release from the mitochondria. Furthermore, overexpression of Bcl-x(L) saved cells from ethanol-induced apoptosis. These data suggest that ethanol-induced apoptosis in liver cells is initiated by the intracellular Ca(2+) elevation in the cytoplasm and activation of TLCK-sensitive serine proteases. Our data provide new insight into ethanol-induced apoptosis in liver cells and may lead to therapeutic strategies to prevent liver damage.

Topics: Amino Acid Chloromethyl Ketones; Apoptosis; bcl-X Protein; Blotting, Western; Calcium; Calmodulin; Calpain; Carcinoma, Hepatocellular; Caspase 3; Caspase 9; Caspases; Cell Separation; Cytochrome c Group; Densitometry; Dose-Response Relationship, Drug; Egtazic Acid; Endopeptidases; Enzyme Activation; Ethanol; Fas Ligand Protein; fas Receptor; Flow Cytometry; Humans; Ions; Liver Neoplasms; Membrane Glycoproteins; Membrane Potentials; Mitochondria; Models, Biological; Proto-Oncogene Proteins c-bcl-2; Reverse Transcriptase Polymerase Chain Reaction; Time Factors; Tosyllysine Chloromethyl Ketone; Transfection; Tumor Cells, Cultured; Tumor Necrosis Factor-alpha

Cell death processes are progressively inactivated during malignant development, in part by loss of tumor suppressors that can promote cell death. The Bin1 gene encodes a nucleocytosolic adaptor protein with tumor suppressor properties, initially identified through its ability to interact with and inhibit malignant transformation by c-Myc and other oncogenes. Bin1 is frequently missing or functionally inactivated in breast and prostate cancers and in melanoma. In this study, we show that Bin1 engages a caspase-independent cell death process similar to type II apoptosis, characterized by cell shrinkage, substratum detachment, vacuolated cytoplasm, and DNA degradation. Cell death induction was relieved by mutation of the BAR domain, a putative effector domain, or by a missplicing event that occurs in melanoma and inactivates suppressor activity. Cells in all phases of the cell cycle were susceptible to death and p53 and Rb were dispensable. Notably, Bin1 did not activate caspases and the broad spectrum caspase inhibitor ZVAD.fmk did not block cell death. Consistent with the lack of caspase involvement, dying cells lacked nucleosomal DNA cleavage and nuclear lamina degradation. Moreover, neither Bcl-2 or dominant inhibition of the Fas pathway had any effect. In previous work, we showed that Bin1 could not suppress cell transformation by SV40 large T antigen. Consistent with this finding, we observed that T antigen suppressed the death program engaged by Bin1. This observation was interesting in light of emerging evidence that T antigen has roles in cell immortalization and human cell transformation beyond Rb and p53 inactivation. In support of a link to c-Myc-induced death processes, AEBSF, a serine protease inhibitor that inhibits apoptosis by c-Myc, potently suppressed DNA degradation by Bin1. Our findings suggest that the tumor suppressor activity of Bin1 reflects engagement of a unique cell death program. We propose that loss of Bin1 may promote malignancy by blunting death penalties associated with oncogene activation.

Topics: Adaptor Proteins, Signal Transducing; Amino Acid Chloromethyl Ketones; Antigens, Polyomavirus Transforming; Apoptosis; Bone Neoplasms; Carcinoma, Hepatocellular; Carrier Proteins; Caspases; Cell Adhesion; Cell Size; Cell Transformation, Neoplastic; Cysteine Proteinase Inhibitors; DNA Fragmentation; Enzyme Activation; fas Receptor; Gene Expression Regulation, Neoplastic; Humans; Liver Neoplasms; Mitochondria; Nuclear Proteins; Osteosarcoma; Protein Structure, Tertiary; Proto-Oncogene Proteins c-bcl-2; Proto-Oncogene Proteins c-myc; Recombinant Fusion Proteins; Retinoblastoma Protein; Serine Proteinase Inhibitors; Sulfones; Tumor Cells, Cultured; Tumor Suppressor Protein p53; Tumor Suppressor Proteins

Transforming growth factor-beta1 (TGF-beta1) arrests growth and/or stimulates apoptosis of a variety of cells. The biochemical pathways involved in the apoptotic processes, however, remain poorly defined. TGF-beta1 induces DNA fragmentation together with morphological changes, which are characteristic of apoptosis in the FaO rat hepatoma cell line. Histones were remarkably enriched in lysates of these cells during TGF beta1-induced apoptosis. We identified U1-70 kd as a death substrate which is cleaved following TGF-beta1 treatment. The tetrapeptide caspase inhibitor carbobenzoxy-valyl-alanly-aspartyl-(beta-O-methyl)-fluoromethyl ketone (ZVAD-FMK) prevented TGF beta1-induced apoptotic DNA fragmentation and cleavage of the U1-70 kd protein, showing that caspase(s) are involved in TGF beta1-mediated apoptosis. To identify specific caspases involved in apoptosis induced by TGF-beta1 in FaO cells, proteolytic activation of several of these caspases and their substrates were studied as a function of time following TGF beta1-treatment. TGF beta1-treatment induced the progressive proteolytic processing of caspase-2 (ICH-1L/Nedd-2), whereas caspase-1 itself did not show any cleavage from the precursor. Pretreatment with ZVAD-FMK abrogated the maturation of caspase-2 and blocked the apoptotic progress. These results suggest that caspase-2, but not caspase-1, may play a crucial role in TGF beta1-induced apoptosis in these cells.

Topics: Amino Acid Chloromethyl Ketones; Animals; Apoptosis; Carcinoma, Hepatocellular; Caspase 1; Caspase 2; Caspase 3; Caspases; Cysteine Endopeptidases; Cysteine Proteinase Inhibitors; Immunoblotting; Liver Neoplasms; Protease Inhibitors; Proteins; Rats; Ribonucleoprotein, U1 Small Nuclear; Time Factors; Transforming Growth Factor beta; Tumor Cells, Cultured

Metastatic rat colon cancer cells but not normal rat hepatocytes showed activity of cathepsin B on their plasma membranes. Activity was visualized in living cells with a new fluorogenic substrate, [Z-Arg]2-cresyl violet, and confocal microscopy. When these cancer cells were injected into the portal vein of rats, the animals developed tumors in the liver in a heterogeneous fashion. Three- to four-fold more tumors were found in the small caudate lobe than in the other three large lobes of the liver. Oral treatment with a selective water-soluble inhibitor of extracellular cathepsin B, Mu-Phe-homoPhe-fluoromethylketone, resulted in 60% reduction of the number of tumors and 80% reduction of the volume of tumors in the three large lobes whereas tumor development was not affected in the small caudate lobe. This study supports the conclusions that (a) extracellular cathepsin B plays a crucial but complex role in liver colonisation by rat colon carcinoma cells in vivo, (b) its selective inhibition suppresses tumor growth heterogeneously in the liver and (c) the caudate lobe of the liver is a relatively large risk factor for tumor development.

Topics: Amino Acid Chloromethyl Ketones; Animals; Cathepsin B; Colonic Neoplasms; Cysteine Proteinase Inhibitors; Extracellular Space; Female; Liver; Liver Neoplasms; Neoplasm Metastasis; Rats; Tumor Cells, Cultured

The two apoptosis receptors of mammalian cells, i.e. the 55 kDa TNF receptor (TNF-R1) and CD95 (Fas/APO1) are activated independently of each other, however, their signaling involves a variety of ICE-related proteases [I]. We used a cell-permeable inhibitor of ICE-like protease activity to examine in vivo whether post-receptor signaling of TNF and CD95 are fully independent processes. Mice pretreated with the inhibitor, Z-VAD-fluoromethylketone (FMK) were dose-dependently protected from liver injury caused by CD95 activation as determined by plasma alanine aminotransferase and also from hepatocyte apoptosis assessed by DNA fragmentation (ID50 = 0.1 mg/kg). A dose of 10 mg/kg protected mice also from liver injury induced by TNF-alpha. Similar results were found when apoptosis was initiated via TNF-alpha or via CD95 in primary murine hepatocytes (IC50 = 1.5 nM) or in various human cell lines. In addition to prevention, an arrest of cell death by Z-VAD-FMK was demonstrated in vivo and in vitro after stimulation of apoptosis receptors. These findings show in vitro and in vivo in mammals that CD95 and the TNF-alpha receptor share a distal proteolytic apoptosis signal.

Topics: Alanine Transaminase; Amino Acid Chloromethyl Ketones; Animals; Antigens, CD; Apoptosis; Carcinoma, Hepatocellular; Caspase 1; Cells, Cultured; Chemical and Drug Induced Liver Injury; Cysteine Endopeptidases; Cysteine Proteinase Inhibitors; DNA Fragmentation; fas Receptor; HeLa Cells; Humans; Interleukin-1; Leukemia-Lymphoma, Adult T-Cell; Lipopolysaccharides; Liver; Liver Neoplasms; Male; Mice; Mice, Inbred BALB C; Receptors, Tumor Necrosis Factor; Receptors, Tumor Necrosis Factor, Type I; Tumor Cells, Cultured; Tumor Necrosis Factor-alpha

Transforming growth factor-beta (TGF-beta) is a potent inducer of programmed cell death in liver as well as some hepatoma cell lines. To explore the mechanism by which TGF-beta induces apoptosis, we investigated the role of caspase family proteases in the apoptotic death of a human hepatoma cell line, Hep3B. We showed that TGF-beta-induced apoptosis was blocked by expression of the cowpox virus protein CrmA, a serpin-like pseudosubstrate for some of the caspase family proteases. CrmA expression, however, did not affect TGF-beta-induced regulation of promoter activities of the cyclin A and plasminogen activator inhibitor type I genes. These results indicate that CrmA inhibits a step specific for the apoptotic effect of TGF-beta. In addition to CrmA, a tripeptide caspase-protease inhibitor, z-Val-Ala-Asp-fluoromethylketone could also suppress TGF-beta-induced apoptosis in a dose-dependent manner. In TGF-beta-treated Hep3B cells, we observed a specific degradation of the catalytic subunit of DNA-dependent protein kinase, which was previously shown to be a substrate of caspase-3 but not several other members of the caspase family. This degradation was not seen in Hep3B cells transfected with CrmA nor in Hep3B cells pretreated with the tripeptide caspase inhibitor. Our study indicates a requirement of caspase family proteases in TGF-beta-induced apoptosis.

Topics: Amino Acid Chloromethyl Ketones; Apoptosis; Carcinoma, Hepatocellular; Caspase 3; Caspases; Cowpox virus; Cyclins; Cysteine Endopeptidases; Cysteine Proteinase Inhibitors; DNA-Activated Protein Kinase; DNA-Binding Proteins; Humans; Liver Neoplasms; Nuclear Proteins; Plasminogen Activator Inhibitor 1; Protein Serine-Threonine Kinases; Receptors, Transforming Growth Factor beta; Serpins; Transforming Growth Factor beta; Tumor Cells, Cultured; Viral Proteins