Anticancer effect of tert-butyl-2(4,5-dihydrogen-4,4,5,5-tetramethyl-3-O-1H-imidazole-3-cationic-1-oxyl-2)-pyrrolidine-1-carboxylic ester on human hepatoma HepG2 cell line

Tert-butyl-2(4,5-dihydrogen-4,4,5,5-tetramethyl-3-O-1H-imidazole-3-cationic-1-oxyl-2)-pyrrolidine-1-carboxylic ester (L-NNP) is a stable nitroxyl nitroxide radical, which have displayed cytotoxicity on human breast cancer MCF-7 and MDA-MB-231 cell lines. In the present study, we investigated the selective cytotoxicity of L-NNP on isogenetic human hepatoma HepG2 and normal L-02 cell lines. Cell growth inhibition, intracellular reactive oxygen species production, the mitochondrial membrane potential loss, malondialdehyde generation and glutathione levels were analyzed. The expression of Bax, Bcl-2 and NF-κBp65 proteins was also examined. The anticancer activity was evaluated in a HepG2 cell xenograft nude mice model. The results showed that 10, 20, 40 μg/ml L-NNP exposure for 48 h caused 52%, 82% and 91% cell growth inhibition of HepG2 cells, compared with 5%, 10% and 15% that of L-02 cells (p < 0.01). Concentrations of 10, 20, 40 μg/ml L-NNP induced cell death by increasing the generation of intracellular reactive oxygen species and MDA, by depolarizing the mitochondrial membrane potential, and by decreasing intracellular GSH levels in HepG2 cells. Western blot assay showed that Bax, Bcl-2 and NF-κBp65 might be implicated in L-NNP-induced selective HepG2 cell death. L-NNP was also found to inhibit HepG2 hepatoma growth and extend the life span of nude mice model (p < 0.01). The pretreatment and co-treatment of 10 mM N-acetyl-cysteine alleviated L-NNP exposure induced intracellular reactive oxygen species increase and cell growth inhibition demonstrated that L-NNP exhibited neoplasm-selective cytotoxicity and pro-apoptotic activities via reactive oxygen species mediated oxidative damage in HepG2 cells. It might be promising for developing a new class of anticancer agent for liver cancer.     

Parthenolide sensitizes hepatocellular carcinoma cells to TRAIL by inducing the expression of death receptors through inhibition of STAT3 activation

This article shows that HepG2, Hep3B, and SK-Hep1 cells, three lines of human hepatocellular carcinoma (HCC) cells, are resistant to apoptosis induced by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Parthenolide, a sesquiterpene lactone found in European feverfew, has been shown to exert both anti-inflammatory and anti-cancer activities. This article demonstrates that co-treatment with parthenolide and TRAIL-induced apoptosis with synergistic interactions in the three lines of HCC cells. In order to explain these effects we ascertained that parthenolide increased either at protein or mRNA level the total content of death receptors TRAIL-R1 and -R2 as well as their surface expression. These effects were found in the three cell lines in the case of TRAIL-R2, while for TRAIL-R1 they were observed in HepG2 and SK-Hep1 cells, but not in Hep3B cells. We suggest that the effects of parthenolide on death receptors depend on the decrease in the level of phosphorylated and active forms of STAT proteins, an event which could be a consequence of the inhibitory effect exerted by parthenolide on the activation of JAK proteins. In agreement with this hypothesis treatment with STAT3 siRNA increased in HCC cells the effect of parthenolide on the expression of death receptors. Sensitization by parthenolide to TRAIL stimulated in the three cell lines the extrinsic mechanism of apoptosis with the activation of both caspases 8 and 3, whereas mitochondria were not involved in the process. Our results suggest that co-treatment with parthenolide and TRAIL could represent a new important therapeutic strategy for hepatic tumors.     

Tumor-targeting Salmonella typhimurium A1-R decoys quiescent cancer cells to cycle as visualized by FUCCI imaging and become sensitive to chemotherapy

Quiescent cancer cells are resistant to cytotoxic agents which target only proliferating cancer cells. Time-lapse imaging demonstrated that tumor-targeting Salmonella typhimurium A1-R (A1-R) decoyed cancer cells in monolayer culture and in tumor spheres to cycle from G₀/G₁ to S/G₂/M, as demonstrated by fluorescence ubiquitination-based cell cycle indicator (FUCCI) imaging. A1-R infection of FUCCI-expressing subcutaneous tumors growing in nude mice also decoyed quiescent cancer cells, which were the majority of the cells in the tumors, to cycle from G₀/G₁ to S/G₂/M, thereby making them sensitive to cytotoxic agents. The combination of A1-R and cisplatinum or paclitaxel reduced tumor size compared with A1-R monotherapy or cisplatinum or paclitaxel alone. The results of this study demonstrate that A1-R can decoy quiescent cancer cells to cycle to S/G₂/M and sensitize them to cytotoxic chemotherapy. These results suggest a new paradigm of bacterial-decoy chemotherapy of cancer.     

Dihydromyricetin Enhances the Chemo-Sensitivity of Nedaplatin via Regulation of the p53/Bcl-2 Pathway in Hepatocellular Carcinoma Cells

Chemotherapy is an effective weapon in the battle against cancer. Nedaplatin (NDP) is an improved platinum-containing drug with lower cytotoxicity than other similar drugs. However, the repeated use of NDP results in substantial hepatocyte damage as well as drug resistance in hepatocellular carcinoma (HCC) cases. Therefore, the development of effective chemotherapy strategies that enhance tumor sensitivity to chemotherapeutics and reduce the secondary damage to liver cells is urgently needed. Dihydromyricetin (DHM), a natural flavonoid compound, has been shown to have antitumor activity with no obvious toxicity to normal cells in vitro and in vivo. In this study, DHM and NDP were combined to treat liver cancer cells; we found that DHM functions as a protector of normal cells compared with the use of NDP alone. In addition, the synergy of DHM with NDP enhanced the effect of NDP on the induction of HCC cell apoptosis. We found that the combination caused clear changes in the level of reactive oxygen species (ROS). Furthermore, we demonstrated that the combination of DHM and NDP activated the p53/Bcl-2 signaling pathway, which resulted in mitochondrial dysfunction and induced cell death and growth inhibition in HCC cells.     

Cdk2 plays a critical role in hepatocyte cell cycle progression and survival in the setting of cyclin D1 expression in vivo

Cdk2 was once believed to play an essential role in cell cycle progression, but cdk2-/- mice have minimal phenotypic abnormalities. In this study, we examined the role of cdk2 in hepatocyte proliferation, centrosome duplication, and survival. Cdk2-/- hepatocytes underwent mitosis and had normal centrosome content after mitogen stimulation. Unlike wild-type cells, cdk2-/- liver cells failed to undergo centrosome overduplication in response to ectopic cyclin D1 expression. After mitogen stimulation in culture or partial hepatectomy in vivo, cdk2-/- hepatocytes demonstrated diminished proliferation. Cyclin D1 is a key mediator of cell cycle progression in hepatocytes, and transient expression of this protein is sufficient to promote robust proliferation of these cells in vivo. In cdk2-/- mice and animals treated with the cdk2 inhibitor seliciclib, cyclin D1 failed to induce hepatocyte cell cycle progression. Surprisingly, cdk2 ablation or inhibition led to massive hepatocyte and animal death following cyclin D1 transfection. In a transgenic model of chronic hepatic cyclin D1 expression, seliciclib induced hepatocyte injury and animal death, suggesting that cdk2 is required for survival of cyclin D1-expressing cells even in the absence of substantial proliferation. In conclusion, our studies demonstrate that cdk2 plays a role in liver regeneration. Furthermore, it is essential for centrosome overduplication, proliferation, and survival of hepatocytes that aberrantly express cyclin D1 in vivo. These studies suggest that cdk2 may warrant further investigation as a target for therapy of liver tumors with constitutive cyclin D1 expression.     

Cytotoxic activity of acetogenins and styryl lactones isolated from Goniothalamus undulatus Ridl. root extracts against a lung cancer cell line (COR-L23)

An investigation of the chemical constituents in a dichloromethnae extract of Goniothalamus undulatus root led to the isolation of three known styryl lactones (5-acetoxyisogoniothalamin oxide, O-acetylaltholactone and altholactone), and four known annonaceous acetogenins (annonacin, cis-annonacin, goniothalamicin and cis-goniothalamicin). These compounds were subjected to a sulphorhodamine B (SRB) cytotoxicity assay against human large cell lung carcinoma (COR-L23), and normal human fetal fibroblast (MRC-5), cell lines. The isolated acetogenins showed higher cytotoxic activity against COR-L23 compared to the styryl lactones, with IC₅₀ values in the range of 0.5-1.7 μM and 7.4-15.4 μM, respectively. A similar pattern of cytotoxicity was also observed against the other cell line (MRC-5); acetogenins IC₅₀ values were in the range of 11.8-31.4 μM, and those for styryl lactones were in the range of 48.7-102.8 μM. This is the first report of a bioassay-guided isolation of chemical constituents from G. undulatus and on cytotoxic studies of the isolated compounds using these particular lung cancer cell lines.     

Characteristics of the killing mechanism of human natural killer cells against hepatocellular carcinoma cell lines HepG2 and Hep3B

Purpose Unlike normal hepatocytes, most hepatocellular carcinomas (HCCs) are quite resistant to death receptor-mediated apoptosis when the cell surface death receptor is cross linked with either agonistic antibodies or soluble death ligand proteins in vitro. The resistance might play an essential role in the escape from the host immune surveillance; however, it has not been directly demonstrated that HCCs are actually resistant to natural killer (NK) cell-mediated death. Therefore, this study investigated the molecular mechanism of NK cell-mediated cytotoxicity against the HCCs, HepG2, and Hep3B, using two distinct cytotoxic assays: a 4-h ⁵¹Cr-release assay and a 2-h [³H] thymidine release assay which selectively measures the extent of necrotic and apoptotic target cell death, respectively.Methods Most of the target cells exhibited marked morphologic changes when they were co-incubated with the NK cells, and the NK cytotoxicity against these HCCs was comparable to that against K562, a NK-sensitive leukemia cell line, when the cytotoxicity was assessed by a 4-h ⁵¹Cr release assay.Results The NK cells also induced significant apoptotic cell death in the Hep3B targets, but not in the HepG2 targets, when the cytotoxicity was assessed by a 2-h [³H]-thymidine release assay. In agreement with these results, procaspase-3 was activated in the Hep3B targets, but not in the HepG2 targets. Interestingly, mildly fixed NK cells had no detectable activity in the 4-h ⁵¹Cr release assay against both HepG2 and Hep3B targets, while they were similarly effective as the untreated NK cells in the 2-h [³H]-thymidine release assay, suggesting that the level of apoptotic cell death of the Hep3B targets is granule independent and might be primarily mediated by the death ligands of the NK cells.Conclusion This study found that a tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)/TRAIL receptor interaction is involved in the NK cell-mediated apoptotic death of the Hep3B targets, but a Fas/Fas ligand (FasL) interaction is not.     

Protection of HepG2 cells against acrolein toxicity by 2-cyano-3,12-dioxooleana-1,9-dien-28-imidazolide via glutathione-mediated mechanism

Acrolein is an environmental toxicant, mainly found in smoke released from incomplete combustion of organic matter. Several studies showed that exposure to acrolein can lead to liver damage. The mechanisms involved in acrolein-induced hepatocellular toxicity, however, are not completely understood. This study examined the cytotoxic mechanisms of acrolein on HepG2 cells. Acrolein at pathophysiological concentrations was shown to cause apoptotic cell death and an increase in levels of protein carbonyl and thiobarbituric acid reactive acid substances. Acrolein also rapidly depleted intracellular glutathione (GSH), GSH-linked glutathione-S-transferases, and aldose reductase, three critical cellular defenses that detoxify reactive aldehydes. Results further showed that depletion of cellular GSH by acrolein preceded the loss of cell viability. To further determine the role of cellular GSH in acrolein-mediated cytotoxicity, buthionine sulfoximine (BSO) was used to inhibit cellular GSH biosynthesis. It was observed that depletion of cellular GSH by BSO led to a marked potentiation of acrolein-mediated cytotoxicity in HepG2 cells. To further assess the contribution of these events to acrolein-induced cytotoxicity, triterpenoid compound 2-cyano-3,12-dioxooleana-1,9-dien-28-imidazolide (CDDO-Im) was used for induction of GSH. Induction of GSH by CDDO-Im afforded cytoprotection against acrolein toxicity in HepG2 cells. Furthermore, BSO significantly inhibited CDDO-Im-mediated induction in cellular GSH levels and also reversed cytoprotective effects of CDDO-Im in HepG2 cells. These results suggest that GSH is a predominant mechanism underlying acrolein-induced cytotoxicity as well as CDDO-Im-mediated cytoprotection. This study may provide understanding on the molecular action of acrolein which may be important to develop novel strategies for the prevention of acrolein-mediated toxicity.     

Characterization of a Novel Anti-Cancer Compound for Astrocytomas

The standard chemotherapy for brain tumors is temozolomide (TMZ), however, as many as 50% of brain tumors are reportedly TMZ resistant leaving patients without a chemotherapeutic option. We performed serial screening of TMZ resistant astrocytoma cell lines, and identified compounds that are cytotoxic to these cells. The most cytotoxic compound was an analog of thiobarbituric acid that we refer to as CC-I. There is a dose-dependent cytotoxic effect of CC-I in TMZ resistant astrocytoma cells. Cell death appears to occur via apoptosis. Following CC-I exposure, there was an increase in astrocytoma cells in the S and G2/M phases. In in vivo athymic (nu/nu) nude mice subcutaneous and intracranial tumor models, CC-I completely inhibited tumor growth without liver or kidney toxicity. Molecular modeling and enzyme activity assays indicate that CC-I selectively inhibits topoisomerase IIα similar to other drugs in its class, but its cytotoxic effects on astrocytoma cells are stronger than these compounds. The cytotoxic effect of CC-I is stronger in cells expressing unmethylated O⁶-methylguanine methyltransferase (MGMT) but is still toxic to cells with methylated MGMT. CC-I can also enhance the toxic effect of TMZ on astrocytoma when the two compounds are combined. In conclusion, we have identified a compound that is effective against astrocytomas including TMZ resistant astrocytomas in both cell culture and in vivo brain tumor models. The enhanced cytotoxicity of CC-I and the safety profile of this family of drugs could provide an interesting tool for broader evaluation against brain tumors.     

Induction of albumin expression in HepG2 cells using immobilized simplified recombinant fibronectin protein

Optimization of the extracellular environment is very important for hepatocyte function in vitro. We expressed new chimeric proteins of the collagen-binding domain (CBD) with cell attachment site (CAS) of fibronectin to enhance hepatocyte function, and the CBD-CAS proteins were immobilized on collagen-coated plates. We hypothesized that the high density of CAS would increase activity of the integrin-dependent intracellular signaling pathway, thus inducing hepatocyte function. Expression of albumin in the human hepatocyte cell line HepG2 was assessed on CBD-CAS-immobilized dishes. The results indicated that the CBD-CAS-immobilized plates induced albumin expression. Immobilized CBD-CAS induced activation of focal adhesion kinase and integrin-ligand clustering on the cell membrane. These results suggest that immobilized CBD-CAS improves the function of HepG2 cells. This system could therefore be applied to drug metabolism assay in the development of new drugs.     

PLGA-Loaded Gold-Nanoparticles Precipitated with Quercetin Downregulate HDAC-Akt Activities Controlling Proliferation and Activate p53-ROS Crosstalk to Induce Apoptosis in Hepatocarcinoma Cells

Controlled release of medications remains the most convenient way to deliver drugs. In this study, we precipitated gold nanoparticles with quercetin. We loaded gold-quercetin into poly(DL-lactide-co-glycolide) nanoparticles (NQ) and tested the biological activity of NQ on HepG2 hepatocarcinoma cells to acquire the sustained release property. We determined by circular dichroism spectroscopy that NQ effectively caused conformational changes in DNA and modulated different proteins related to epigenetic modifications and c ell cycle control. The mitochondrial membrane potential (MMP), reactive oxygen species (ROS), cell cycle, apoptosis, DNA damage, and caspase 3 activity were analyzed by flow cytometry, and the expression profiles of different anti- and pro-apoptotic as well as epigenetic signals were studied by immunoblotting. A cytotoxicity assay indicated that NQ preferentially killed cancer cells, compared to normal cells. NQ interacted with HepG2 cell DNA and reduced histone deacetylases to control cell proliferation and arrest the cell cycle at the sub-G stage. Activities of cell cycle-related proteins, such as p21^WAF, cdk1, and pAkt, were modulated. NQ induced apoptosis in HepG2 cells by activating p53-ROS crosstalk and induces epigenetic modifications leading to inhibited proliferation and cell cycle arrest.     

Cytotoxic Activity and Apoptosis-Inducing Potential of Di-spiropyrrolidino and Di-spiropyrrolizidino Oxindole Andrographolide Derivatives

Anticancer role of andrographolide is well documented. To find novel potent derivatives with improved cytotoxicity than andrographolide on cancer cells, two series of di-spiropyrrolidino- and di-spiropyrrolizidino oxindole andrographolide derivatives prepared by cyclo-addition of azomethine ylide along with sarcosine or proline (viz. sarcosine and proline series respectively) and substitution of different functional groups (-CH3, -OCH3 and halogens) were examined for their cytotoxic effect on a panel of six human cancer cell lines (colorectal carcinoma HCT116 cells, pancreatic carcinoma MiaPaCa-2 cells, hepatocarcinoma HepG2 cells, cervical carcinoma HeLa cells, lung carcinoma A549 and melanoma A375 cells). Except halogen substituted derivatives of proline series (viz. CY2, CY14 and CY15 for Br, Cl and I substitution respectively), none of the other derivatives showed improved cytotoxicity than andrographolide in the cancer cell lines examined. Order of cytotoxicity of the potent compounds is CY2>CY14>CY15>andrographolide. Higher toxicity was observed in HCT116, MiaPaCa-2 and HepG2 cells. CY2, induced death of HCT116 (GI₅₀ 10.5), MiaPaCa-2 (GI₅₀ 11.2) and HepG2 (GI₅₀ 16.6) cells were associated with cell rounding, nuclear fragmentation and increased percentage of apoptotic cells, cell cycle arrest at G1 phase, ROS generation, and involvement of mitochondrial pathway. Upregulation of Bax, Bad, p53, caspases-3,-9 and cleaved PARP; downregulation of Bcl-2, cytosolic NF-κB p65, PI3K and p-Akt; translocation of P53/P21, NF-κB p65 were seen in CY2 treated HCT116 cells. Thus, three halogenated di-spiropyrrolizidino oxindole derivatives of andrographolide are found to be more cytotoxic than andrographolide in some cancer cells. The most potent derivative, CY2 induced death of the cancer cells involves ROS dependent mitochondrial pathway like andrographolide.     

Targeting Nrf2 with wogonin overcomes cisplatin resistance in head and neck cancer

A principal limitation to the clinical use of cisplatin is the high incidence of chemoresistance to this drug. Combination treatments with other drugs may help to circumvent this problem. Wogonin, one of the major natural flavonoids, is known to reverse multidrug resistance in several types of cancers. We investigated the ability of wogonin to overcome cisplatin resistance in head and neck cancer (HNC) cells and further clarified its molecular mechanisms of action. Two cisplatin-resistant HNC cell lines (AMC-HN4R and -HN9R) and their parental and other human HNC cell lines were used. The effects of wogonin, either alone or in combination with cisplatin, were assessed in HNC cells and normal cells using cell cycle and death assays and by measuring cell viability, reactive oxygen species (ROS) production, and protein expression, and in tumor xenograft mouse models. Wogonin selectively killed HNC cells but spared normal cells. It inhibited nuclear factor erythroid 2-related factor 2 and glutathione S-transferase P in cisplatin-resistant HNC cells, resulting in increased ROS accumulation in HNC cells, an effect that could be blocked by the antioxidant N-acetyl-l-cysteine. Wogonin also induced selective cell death by targeting the antioxidant defense mechanisms enhanced in the resistant HNC cells and activating cell death pathways involving PUMA and PARP. Hence, wogonin significantly sensitized resistant HNC cells to cisplatin both in vitro and in vivo. Wogonin is a promising anticancer candidate that induces ROS accumulation and selective cytotoxicity in HNC cells and can help to overcome cisplatin-resistance in this cancer.     

N-acetylglycoside of oleanolic acid (aridanin) displays promising cytotoxicity towards human and animal cancer cells,inducing apoptotic,ferroptotic and necroptotic cell death

BackgroundThe discovery of novel phytochemicals represents a reasonable approach to fight malignancies, especially those which are resistant to standard chemotherapy.PurposeWe evaluated the cytotoxic potential of a naturally occurring N-acetylglycoside of oleanolic acid, aridanin, on 18 cancer cell lines, including sensitive and drug-resistant phenotypes mediated by P-glycoprotein, BCRP, p53 knockout, deletion-mutated EGFR, or BRAF mutations. Furthermore, metastasizing B16/F10 cells, HepG2 hepatocarcinoma and normal AML12 hepatocytes were investigated. The mechanisms of aridanin-induced cell death was further investigated.MethodsThe resazurin reduction assay (RRA) was applied to evaluate the cytotoxicity, autophagy, ferroptotic and necroptotic cell death. CCRF-CEM leukemia cells were used for all mechanistic studies. A caspase-Glo assay was applied to evaluate the caspase activities. Flow cytometry was applied for the analyses of cell cycle (PI staining), apoptosis (annexin V/PI staining), mitochondrial membrane potential (MMP; JC-1) and reactive oxygen species (ROS; H₂DCFH-DA).ResultsAridanin and doxorubicin (positive control) inhibited the proliferation of all cancer cell lines tested. The IC₅₀ values for aridanin varied from 3.18 µM (CCRF-CEM cells) to 9.56 µM (HepG2 cells). Aridanin had considerably lower IC₅₀ values than that of doxorubicin against multidrug-resistant CEM/ADR5000 cells and melanoma cell lines (MaMel-80a, Mel-2a, MV3, and SKMel-505). Aridanin induced apoptosis in CCRF-CEM cells through increase of ROS levels and MMP breakdown, and to a lesser extent via caspases activation. Aridanin also induced ferroptotic and necroptotic cell death.ConclusionThe present study opens good perpectives for the use of this phytochemical as an anticancer drug to combat multi-facorial resistance to established chemotherapeutics.     

Liver regeneration associated protein (ALR) exhibits antimetastatic potential in hepatocellular carcinoma

Augmenter of liver regeneration (ALR), which is critically important in liver regeneration and hepatocyte proliferation, is highly expressed in cirrhotic livers and hepatocellular carcinomas (HCC). In the current study, the functional role of ALR in hepatocancerogenesis was analyzed in more detail. HepG2 cells, in which the cytosolic 15 kDa ALR isoform was reexpressed stably, (HepG2-ALR) were used in migration and invasion assays using modified Boyden chambers. Epithelial-mesenchymal transition (EMT) markers were determined in HepG2-ALR cells in vitro and in HepG2-ALR tumors grown in nude mice. ALR protein was quantified in HCC and nontumorous tissues by immunohistochemistry. HepG2-ALR, compared with HepG2 cells, demonstrated reduced cell motility and increased expression of the epithelial cell markers E-cadherin and Zona occludens-1 (ZO-1), whereas SNAIL, a negative regulator of E-cadherin, was diminished. Matrix metalloproteinase MMP1 and MMP3 mRNA expression and activity were reduced. HepG2-ALR cell-derived subcutaneously grown tumors displayed fewer necrotic areas, more epithelial-like cell growth and fewer polymorphisms and atypical mitotic figures than tumors derived from HepG2 cells. Analysis of tumor tissues of 53 patients with HCC demonstrated an inverse correlation of ALR protein with histological angioinvasion and grading. The 15 kDa ALR isoform was found mainly in HCC tissues without histological angioinvasion 0. In summary the present data indicate that cytosolic ALR reduces hepatoma cell migration, augments epithelial growth and, therefore, may act as an antimetastatic and EMT reversing protein.     

Human normal hepatocytes are susceptible to apoptosis signal mediated by both TRAIL-R1 and TRAIL-R2

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) triggers apoptosis in tumor cells without toxicity to normal cells, but some recombinant versions of TRAIL caused hepatocyte death. We generated fully human monoclonal antibodies (mAbs) that bind specifically to TRAIL receptor 1 (TRAIL-R1) and TRAIL receptor 2 (TRAIL-R2), which mediate apoptosis signal when they ligate with TRAIL, to investigate the contribution of each receptor to induce tumor cell apoptosis and hepatocyte toxicity. All of mAbs to TRAIL-R1 and TRAIL-R2 induced cell death in several cancer cell lines susceptible to TRAIL but not in human umbilical vein endothelial cells in vitro. Both anti-TRAIL-R1 mAbs and anti-TRAIL-R2mAbs also caused cell death in hepatocytes. However, a subset of mAbs to TRAIL-R2, which was characterized by the TRAIL blocking activity, did not show strong hepatocyte toxicity. These results indicate that human normal hepatocytes are susceptible to both TRAIL-R1- and TRAIL-R2-mediated apoptosis signal.Cell Death and Differentiation (2004) 11, 203-207. doi:10.1038/sj.cdd.4401331 Published online 24 October 2003     

Bioactive compounds from brown seaweeds: Phloroglucinol,fucoxanthin and fucoidan as promising therapeutic agents against breast cancer

Breast cancer is one of the most common cancers among women and its incidence tends to increase year by year. Chemotherapy is an effective treatment for many types of cancer, however its toxicity in normal cells and acquired tumor resistance to the drug used are considered as the main barriers. New strategies have been proposed to increase the success of anticancer drugs namely it combination with natural dietary compounds, decreasing drug dose administered and reducing its toxicity to normal cells. Seaweeds are rich in bioactive compounds and, in Traditional Chinese Medicine and Japanese folk medicine are used to “treat” tumors. Attending to the attractive biological effects of some seaweed several efforts have been made to isolate the bioactive compounds and explore its action mechanisms. Phloroglucinol, fucoxanthin and fucoidan are bioactive compounds present in brown seaweed showing chemopreventive and chemotherapeutic effects against cancer. Several mechanisms namely antioxidant, cell cycle arrest, induction of cell death and inhibition of metastasis and angiogenesis have been mentioned as responsible for it anticancer activity. Beside the promising biological effects of these compounds, synergistic effects with cytotoxic drugs have been less explored. This review focuses on the potential protective and therapeutic effect – mainly against breast cancer – of the bioactive compounds phloroglucinol, fucoxanthin and fucoidan present in the brown seaweeds. Current knowledge about interaction between each of these compounds and the conventional anticancer drugs and the further research opportunities are discussed.     

Morin hydrate: a potential antioxidant in minimizing the free-radicals-mediated damage to cardiovascular cells by anti-tumor drugs

The co-incubation of morin hydrate with either doxorubicin or mitomycin C could minimize the toxicity of these anti-tumor drugs on cardiovascular cells, such as red blood cells, human umbilical vein endothelial cells (ECV304) and primary mouse cardiomyocytes, whereas morin hydrate did not lower the cytotoxicity of the drugs on human hepatocellular carcinoma cells (HepG2). Morin hydrate may not exert its antioxidant effect by enhancing the antioxidant enzymatic activity because it did not cause any induction on the mRNA levels of manganese superoxide dismutase expression in ECV304 cells and HepG2 cells.     

Taiwanin A induced cell cycle arrest and p53-dependent apoptosis in human hepatocellular carcinoma HepG2 cells

Taiwanin A, a lignan isolated from Taiwania cryptomerioides Hayata, has previously been reported to have cytotoxicity against human tumor cells, but the mechanisms are unclear. In this study, we examined the molecular mechanism of cell death of human hepatocellular carcinoma HepG2 cells induced by Taiwanin A. Taiwanin A has been found to induce cell cycle arrest at G2/M phase as well as caspase-3-dependent apoptosis within 24 h. We performed both in vitro turbidity assay and immunofluorescence staining of tubulin to show that Taiwanin A can inhibit microtubule assembly. Moreover, the tumor suppressor protein p53 in HepG2 cells was activated by Taiwanin A within 12 h. Inhibition of p53 by either pifithrin-alpha or by short hairpin RNA which blocks p53 expression attenuates Taiwanin A cytotoxicity. Our results demonstrate that Taiwanin A can act as a new class of microtubule damaging agent, arresting cell cycle progression at mitotic phase and inducing apoptosis through the activation of p53.