Critical upstream signals of cytochrome C release induced by a novel Bcl-2 inhibitor

Doxorubicin impairs cognitive function by upregulating AMPAR and NMDAR subunit expression and increasing neuroinflammation, oxidative stress, and apoptosis in the brain

Introduction: The anticancer drug doxorubicin (DOX) is used for various malignancies. However, it also causes cognitive impairment in cancer survivors. In order to determine the mechanisms underlying the acute effects of DOX, we assessed the mRNA and protein expression of glutamate receptors and proteins involved in cognitive function and apoptosis. Methods: Fear-conditioning memory tests were performed in rats after a single intraperitoneal injection of DOX (25 mg/kg) to evaluate short-term memory function. Rat brain samples were collected, and GluA1 mRNA and protein expression; NR2A and NR2B mRNA expression; and COX-2, NF-kB, TNF-α, and MDA, Bax, and caspase-3 levels were assessed via reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assays. Results: We observed a decreased number of entries in Y-maze, decreased exploration time to the novel object in the novel object recognition (NOR), and decreased freezing time in the fear-conditioning memory tests in DOX-treated rats relative to those in control rats, demonstrating cognitive impairment. GluA1, NR2B, and NR2A expression and MDA, NF-κB, Bax, COX-2, TNF-α, and caspase-3 levels in the brain were significantly elevated in DOX-treated rats. Conclusion: DOX induced cognitive impairment in the rats via neuronal toxicity by upregulating AMPAR and NMDAR expression and increasing neuroinflammation, oxidative stress, and apoptosis in the brain.

In vivo Study of a Newly Synthesized Chromen-4-one Derivative as an Antitumor Agent against HCC

BACKGROUND

Chromenes are a wide group of natural compounds that can be synthesized chemically. The chromen-4-one nucleus acts as a skeleton for varieties of additional active groups that makes the chromene activity vary between antioxidant and anti-inflammatory agents. In the present study, a newly synthesized chromene compound exhibits different behaviors other than anti-inflammatory and antioxidant activities that it is the first time that a member of chromen-4-one compound can control the cancer progress. Inflammation is the first step in tumor development where the severity grade can potentiate tumor growth and progression. In many tumors, pro-inflammatory genes record high expression level such as tumor necrosis factor (TNF-α) and vascular endothelial growth factors (VEGF). These pro-inflammatory factors act as rate limiting steps in tumor initiation, and controlling its expression acts as an early therapeutic way to control the tumor proliferation. The chromone derivatives have biological activities such as anti-inflammatory and anti-tumor activity.

METHODS

In the present study, hepatocellular cancer (HCC) induced by diethylnitrosamine (DEN) in rats and then treated with the new chromene derivative and the parameters TNF-α, VEGF, p53, Cyt C, MMP-9, Bcl2, and Bax were measured.

RESULTS

The treatment strategy Ch compound is to downregulate pro-inflammatory gene expression of early genes as TNF-α as well as VEGF and subsequently control other factors such as p53, Cyt C, and MMP-9. Also, retrieve the balance between Bcl2 and Bax proteins in DEN-induced HCC in rats.

CONCLUSION

The ability of the new Ch derivative to control the primary initiators of HCC such as TNF-α offers this derivative an anti-tumor activity and encourages further researches to follow and monitor its effect on the molecular level.

Critical View of Novel Treatment Strategies for Glioblastoma: Failure and Success of Resistance Mechanisms by Glioblastoma Cells

According to the invasive nature of glioblastoma, which is the most common form of malignant brain tumor, the standard care by surgery, chemo- and radiotherapy is particularly challenging. The presence of glioblastoma stem cells (GSCs) and the surrounding tumor microenvironment protects glioblastoma from recognition by the immune system. Conventional therapy concepts have failed to completely remove glioblastoma cells, which is one major drawback in clinical management of the disease. The use of small molecule inhibitors, immunomodulators, immunotherapy, including peptide and mRNA vaccines, and virotherapy came into focus for the treatment of glioblastoma. Although novel strategies underline the benefit for anti-tumor effectiveness, serious challenges need to be overcome to successfully manage tumorigenesis, indicating the significance of developing new strategies. Therefore, we provide insights into the application of different medications in combination to boost the host immune system to interfere with immune evasion of glioblastoma cells which are promising prerequisites for therapeutic approaches to treat glioblastoma patients.

Vitex Rotundifolia Fractions Induced Apoptosis in Human Breast Cancer T-47D Cell Line via Activation of Extrinsic and Intrinsic Pathway

OBJECTIVE

Breast cancer is the most frequently diagnosed cancer worldwide. The main objective of the present study was to evaluate the cytotoxic effects and mechanism of cell death induced by the extract and fractions of Vitex rotundifolia (leaves) in breast cancer cell line, T-47D.

METHODS

The cytotoxicity activity was measured using MTS assay. The mode of cell death was analysed by early (phosphatidylserine externalization) and late apoptosis (DNA fragmentation). The caspases 8, 9, 3/7 and apoptotic proteins bax, bcl-2 study were done by western blot and ELISA method.

RESULTS

The methanol extract was found to inhibit 50% growth of T-47D cells at the concentration of 79.43µg/ml respectively after 72hr. From seven fractions, fraction F1, F2 and F3 produced cytotoxicity effects in T-47D cell line with IC50 (72hr) < 30µg/ml. The results obtained by Annexin V/PI apoptosis detection assay and TUNEL assay suggest that active fractions of  Vitex rotundifolia induced early and late apoptosis (DNA fragmentation) in T-47D cell line. Moreover, western blot analysis and Caspase GloTM luminescent assay demonstrated that fractions F2 and F3 triggered apoptotic cell death via activation of caspases -8, -9 and -3/7 and up-regulation of  Bax and down-regulation of Bcl-2 protein.  Furthermore, chemical profiling confirms the presence of potential metabolites (vitexicarpin) in fractions of Vitex rotundifolia.

CONCLUSION

Thus, the present study suggests the remarkable potential of active metabolites in fractions of Vitex rotundifolia as future cancer therapeutic agent for the treatment of breast cancer.
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Pharmacokinetics of a novel microtubule inhibitor mHA11 in rats

mHA11, a 2-amino-4-phenyl-4H-chromene-3-carboxylate analog, is a microtubule-targeting agent discovered by our group through the modification of the Bcl-2 inhibitor HA14-1. mHA11 exhibits cytotoxicities against tumor cells with nM IC₅₀ values, whereas it has only a minimal effect on normal cells. We explored the plasma pharmacokinetics, tissue distribution, and excretion of mHA11 in rats using a liquid chromatography/tandem mass spectrometry (LC-MS/MS) method. Next, we identified the metabolites of mHA11 and assessed the influence of cytochrome P450 (CYP) isozymes on mHA11 metabolism. We also examined the in vitro stability in rat plasma and rat liver microsomes (RLMs), the blood-to plasma (B/P) ratio, and the inhibitory effect on CYP isozyme activities. After oral administration at 5, 15, and 45 mg/kg, mHA11 was absorbed and eliminated rapidly. There was a linear correlation between the area under the concentration-time curve (AUC_0-∞) and the dose (R² = 0.983). The bioavailability of mHA11 was 4.1% at the oral dose of 15 mg/kg mHA11 was extensively distributed in various tissues and exhibited a high penetration into the brain. No significant parent drug was detected in urine or bile, and only 0.74% was recovered in feces, whereas two demethylated metabolites, M1 and M2, were found in the urine and feces, and further studies showed that CYP2C19 primarily contributed to metabolites formation. mHA11 was stable in rat plasma but degraded significantly in RLMs; its B/P ratio was 1.05 in rat blood. In addition, mHA11 dose-dependently inhibited the activities of rat CYP isozymes, including CYP1A2, CYP2C6, CYP2C11, CYP2D2, CYP2E1 and CYP3A2. The present study is the first report on the disposition of mHA11 in rats and provides important data for further research and development of this inhibitor.

Chemotherapy priming of the Pancreatic Tumor Microenvironment Promotes Delivery and Anti-Metastasis Efficacy of Intravenous Low-Molecular-Weight Heparin-Coated Lipid-siRNA Complex

Pancreatic ductal adenocarcinoma (PDAC) is a type of malignant tumor with high lethality. Its high tumor cell-density and large variety of extracellular matrix (ECM) components present major barriers for drug delivery.

Methods: Paclitaxel-loaded PEGylated liposomes (PTX-Lip) were used as a tumor-priming agent to induce tumor cell apoptosis and decrease the abundance of ECM to promote cellular uptake and tumor delivery of nanodrugs. Paclitaxel exerts anti-cancer effects but, paradoxically, exacerbates cancer metastasis and drug resistance by increasing the expression of apoptotic B-cell lymphoma-2 protein (BCL-2). Thus, low-molecular-weight heparin-coated lipid-siRNA complex (LH-Lip/siBCL-2) was constructed to inhibit cancer metastasis and silence BCL-2 by BCL-2 siRNA (siBCL-2).

Results: Significant tumor growth inhibition efficacy was observed, accompanied by obvious inhibition of cancer metastasis in vivo.

Conclusion: These results suggested our sequential delivery of PTX-Lip and LH-Lip/siBCL-2 might provide a practical approach for PDAC or other ECM-rich tumors.

Hyperglycemia-induced oxidative stress and heart disease-cardioprotective effects of rooibos flavonoids and phenylpyruvic acid-2-O-β-D-glucoside

Diabetic patients are at an increased risk of developing heart failure when compared to their non-diabetic counter parts. Accumulative evidence suggests chronic hyperglycemia to be central in the development of myocardial infarction in these patients. At present, there are limited therapies aimed at specifically protecting the diabetic heart at risk from hyperglycemia-induced injury. Oxidative stress, through over production of free radical species, has been hypothesized to alter mitochondrial function and abnormally augment the activity of the NADPH oxidase enzyme system resulting in accelerated myocardial injury within a diabetic state. This has led to a dramatic increase in the exploration of plant-derived materials known to possess antioxidative properties. Several edible plants contain various natural constituents, including polyphenols that may counteract oxidative-induced tissue damage through their modulatory effects of intracellular signaling pathways. Rooibos, an indigenous South African plant, well-known for its use as herbal tea, is increasingly studied for its metabolic benefits. Prospective studies linking diet rich in polyphenols from rooibos to reduced diabetes associated cardiovascular complications have not been extensively assessed. Aspalathin, a flavonoid, and phenylpyruvic acid-2-O-β-D-glucoside, a phenolic precursor, are some of the major compounds found in rooibos that can ameliorate hyperglycemia-induced cardiomyocyte damage in vitro. While the latter has demonstrated potential to protect against cell apoptosis, the proposed mechanism of action of aspalathin is linked to its capacity to enhance the expression of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) expression, an intracellular antioxidant response element. Thus, here we review literature on the potential cardioprotective properties of flavonoids and a phenylpropenoic acid found in rooibos against diabetes-induced oxidative injury.

Enhancement of Radiation Sensitivity in Lung Cancer Cells by a Novel Small Molecule Inhibitor That Targets the β-Catenin/Tcf4 Interaction

Radiation therapy is an important treatment choice for unresectable advanced human lung cancers, and a critical adjuvant treatment for surgery. However, radiation as a lung cancer treatment remains far from satisfactory due to problems associated with radiation resistance in cancer cells and severe cytotoxicity to non-cancer cells, which arise at doses typically administered to patients. We have recently identified a promising novel inhibitor of β-catenin/Tcf4 interaction, named BC-23 (C₂₁H₁₄ClN₃O₄S), which acts as a potent cell death enhancer when used in combination with radiation. Sequential exposure of human p53-null non-small cell lung cancer (NSCLC) H1299 cells to low doses of x-ray radiation, followed 1 hour later by administration of minimally cytotoxic concentrations of BC-23, resulted in a highly synergistic induction of clonogenic cell death (combination index <1.0). Co-treatment with BC-23 at low concentrations effectively inhibits Wnt/β-catenin signaling and down-regulates c-Myc and cyclin D1 expression. S phase arrest and ROS generation are also involved in the enhancement of radiation effectiveness mediated by BC-23. BC-23 therefore represents a promising new class of radiation enhancer.

Bax regulates neuronal Ca2+ homeostasis

Excessive Ca(2+) entry during glutamate receptor overactivation ("excitotoxicity") induces acute or delayed neuronal death. We report here that deficiency in bax exerted broad neuroprotection against excitotoxic injury and oxygen/glucose deprivation in mouse neocortical neuron cultures and reduced infarct size, necrotic injury, and cerebral edema formation after middle cerebral artery occlusion in mice. Neuronal Ca(2+) and mitochondrial membrane potential (Δψm) analysis during excitotoxic injury revealed that bax-deficient neurons showed significantly reduced Ca(2+) transients during the NMDA excitation period and did not exhibit the deregulation of Δψm that was observed in their wild-type (WT) counterparts. Reintroduction of bax or a bax mutant incapable of proapoptotic oligomerization equally restored neuronal Ca(2+) dynamics during NMDA excitation, suggesting that Bax controlled Ca(2+) signaling independently of its role in apoptosis execution. Quantitative confocal imaging of intracellular ATP or mitochondrial Ca(2+) levels using FRET-based sensors indicated that the effects of bax deficiency on Ca(2+) handling were not due to enhanced cellular bioenergetics or increased Ca(2+) uptake into mitochondria. We also observed that mitochondria isolated from WT or bax-deficient cells similarly underwent Ca(2+)-induced permeability transition. However, when Ca(2+) uptake into the sarco/endoplasmic reticulum was blocked with the Ca(2+)-ATPase inhibitor thapsigargin, bax-deficient neurons showed strongly elevated cytosolic Ca(2+) levels during NMDA excitation, suggesting that the ability of Bax to support dynamic ER Ca(2+) handling is critical for cell death signaling during periods of neuronal overexcitation.

Investigation of Astragalus honey and propolis extract's cytotoxic effect on two human cancer cell lines and their oncogen and proapoptotic gene expression profiles

Background:

Cancer is one of the major fatal human diseases. Natural products have been used in the treatment of cancer for long time. Bee products including honey and propolis have been introduced for malignancy treatment in recent decades. In this study cytotoxicity of bee products and their effects on the expression of proapoptotic genes have been investigated.

Materials and Methods:

Cytotoxic effects of Astragalus honey, ethanol extract of propolis and a sugar solution (as control) against HepG2, 5637 and L929 cell lines have been evaluated by the MTT assay. Total RNAs of treated cells were isolated and p53 and Bcl-2 gene expression were evaluated, using real-time PCR.

Results:

Propolis IC50 values were 58, 30 and 15 μg/ml against L929, HepG2 and 5637, respectively. These values for honey were 3.1%, 2.4% and 1.9%, respectively. Propolis extract has increased the expression of the Bcl-2 gene in all cell lines whereas the honey decreased that significantly (P < 0.05). Also, we found that honey and propolis decreased p53 gene expression in HepG2 and 5637 significantly but not in L929 cells. The sugar solution increased the expression of p53 in two cancer cell lines but no significant changes were observed in the expression of this gene in L929 as normal mouse cell.

Conclusion:

By downregulation of Bcl-2 expression it could be concluded that the cytotoxicity of honey was more than two fold against tested cancer cells compared with the sugar solution. No significant changes were observed in the expression of p53 in honey-treated cells. Propolis had no significant effect on Bcl-2 and p53 gene expressions (P > 0.05).

Cracking the cytotoxicity code: apoptotic induction of 10-acetylirciformonin B is mediated through ROS generation and mitochondrial dysfunction

A marine furanoterpenoid derivative, 10-acetylirciformonin B (10AB), was found to inhibit the proliferation of leukemia, hepatoma, and colon cancer cell lines, with selective and significant potency against leukemia cells. It induced DNA damage and apoptosis in leukemia HL 60 cells. To fully understand the mechanism behind the 10AB apoptotic induction against HL 60 cells, we extended our previous findings and further explored the precise molecular targets of 10AB. We found that the use of 10AB increased apoptosis by 8.9%-87.6% and caused disruption of mitochondrial membrane potential (MMP) by 15.2%-95.2% in a dose-dependent manner, as demonstrated by annexin-V/PI and JC-1 staining assays, respectively. Moreover, our findings indicated that the pretreatment of HL 60 cells with N-acetyl-l-cysteine (NAC), a reactive oxygen species (ROS) scavenger, diminished MMP disruption and apoptosis induced by 10AB, suggesting that ROS overproduction plays a crucial rule in the cytotoxic activity of 10AB. The results of a cell-free system assay indicated that 10AB could act as a topoisomerase catalytic inhibitor through the inhibition of topoisomerase IIα. On the protein level, the expression of the anti-apoptotic proteins Bcl-xL and Bcl-2, caspase inhibitors XIAP and survivin, as well as hexokinase II were inhibited by the use of 10AB. On the other hand, the expression of the pro-apoptotic protein Bax was increased after 10AB treatment. Taken together, our results suggest that 10AB-induced apoptosis is mediated through the overproduction of ROS and the disruption of mitochondrial metabolism.

Ginsenoside F(2) induces apoptosis in humor gastric carcinoma cells through reactive oxygen species-mitochondria pathway and modulation of ASK-1/JNK signaling cascade in vitro and in vivo

Ginsenoside F(2) (F(2)) is a potential bioactive metabolite of major ginsenosides. The potential anti-cancer effect of F(2) in gastric cancer cells has not been appraised. This study investigated the effects of F(2) on the production of reactive oxygen species (ROS). We also investigated the in vitro and in vivo effects of F(2) on the downstream signaling pathways leading to apoptosis in human gastric cancer cells. The in vitro data revealed that F(2) induces ROS accumulation followed by a decrease in mitochondrial transmembrane potential (MTP), and the release of cytochrome c (cyto c), which induced the caspase-dependent apoptosis. Further assay indicated that modulation of ASK-1/JNK pathway contributes to apoptosis. In vivo, F(2) exhibits the obvious anti-cancer effect compared with cisplatin with no obvious toxicity. Jointly, these results suggest that F(2) induces apoptosis by causing an accumulation of ROS and activating the ASK-1/JNK signaling pathway. This provides further support for the use of F(2) as a novel anticancer therapeutic candidate.

Regulation of HA14-1 mediated oxidative stress, toxic response, and autophagy by curcumin to enhance apoptotic activity in human embryonic kidney cells

An alteration in susceptibility to apoptosis not only contributes to promotion of malignancy but can also enhance drug resistance in response to anticancer therapies. HA14-1 is a small molecule which has the potential of inducing apoptosis in cancerous cells. HA14-1 manifests an antagonistic effect on antiapoptotic protein Bcl-2 and consequently induces cell death in various cancerous cell lines. However, it is also known to generate ROS and toxic response in the cells upon decomposition. Elevated level of ROS is responsible for oxidative stress and other pathological consequences, if not metabolized properly. The aim of the present study was to examine the synergistic effect of curcumin in promoting apoptosis by regulating the HA14-1 mediated ROS generation, toxicity, oxidative stress, and autophagy in human embryonic kidney cells. Our study demonstrates that curcumin efficiently scavenges HA14-1 mediated generation of ROS and toxic response resulting in augmentation of apoptosis in HEK 293T cells by promoting inhibition of antiapoptotic proteins and process of autophagy. Thus curcumin along with HA14-1 regulates cell proliferation by disruption of the antiapoptotic signaling mechanism. This approach could serve as a promising strategy for therapeutic potential to overcome their adverse effects.

Development of a novel class of tubulin inhibitors with promising anticancer activities

We have developed a novel class (2-amino-4-phenyl-4H-chromene-3-carboxylate) of inhibitors of tubulin assembly by modifying HA14-1, which is a Bcl-2 inhibitor discovered by our group. Three of these compounds, mHA1, mHA6, and mHA11, showed in vitro cytotoxicities against tumor cells that were more potent and more stable than the backbone compound HA14-1, with nM IC50 values. In contrast, the cytotoxic effects of these compounds on normal cells were minimal. Computational docking, colchicine-tubulin competitive binding, and tubulin polymerization studies demonstrated that these compounds bind at the colchicine-binding site on tubulin and inhibit the formation of microtubules. Treatment of HL-60/Bcl-2 leukemia and CRL5908 lung cancer cells with these mHA compounds led to pronounced microtubule density decreases, G2/M cell cycle arrest, and apoptosis, as determined by immunofluorescence microscopy, flow cytometry, and DNA fragmentation analysis. Combined, these data identify a novel class of compounds that inhibit tubulin assembly and limit cancer cell phenotypes.

IMPLICATIONS

This study supports the continued development of novel anti-tubulin assembly inhibitors as potential anticancer agents.

Omega-3 fatty acids in neurodegenerative diseases: focus on mitochondria

Mitochondrial dysfunction represents a common early pathological event in brain aging and in neurodegenerative diseases, e.g., in Alzheimer's (AD), Parkinson's (PD), and Huntington's disease (HD), as well as in ischemic stroke. In vivo and ex vivo experiments using animal models of aging and AD, PD, and HD mainly showed improvement of mitochondrial function after treatment with polyunsaturated fatty acids (PUFA) such as docosahexaenoic acid (DHA). Thereby, PUFA are particular beneficial in animals treated with mitochondria targeting toxins. However, DHA showed adverse effects in a transgenic PD mouse model and it is not clear if a diet high or low in PUFA might provide neuroprotective effects in PD. Post-treatment with PUFA revealed conflicting results in ischemic animal models, but intravenous administered DHA provided neuroprotective efficacy after acute occlusion of the middle cerebral artery. In summary, the majority of preclinical data indicate beneficial effects of n-3 PUFA in neurodegenerative diseases, whereas most controlled clinical trials did not meet the expectations. Because of the high half-life of DHA in the human brain clinical studies may have to be initiated much earlier and have to last much longer to be more efficacious.

OGDHL is a modifier of AKT-dependent signaling and NF-κB function

Oxoglutarate dehydrogenase (OGDH) is the first and rate-limiting component of the multi-enzyme OGDH complex (OGDHC) whose malfunction is associated with neuro-degeneration. The essential role of this complex is in the degradation of glucose and glutamate and the OGDHL gene (one component of OGDHC) is down-regulated by promoter hypermethylation in many different cancer types. These properties suggest a potential growth modulating role of OGDHL in cancer; however, the molecular mechanism through which OGDHL exerts its growth modulating function has not been elucidated.

Here, we report that restoration of OGDHL expression in cervical cancer cells lacking endogenous OGDHL expression suppressed cell proliferation, invasion and soft agar colony formation in vitro. Knockdown of OGDHL expression in cervical cancer cells expressing endogenous OGDHL had the opposite effect. Forced expression of OGDHL increased the production of reactive oxygen species (ROS) leading to apoptosis through caspase 3 mediated down-regulation of the AKT signaling cascade and decreased NF-κB phosphorylation. Conversely, silencing OGDHL stimulated the signaling pathway via increased AKT phosphorylation. Moreover, the addition of caspase 3 or ROS inhibitors in the presence of OGDHL increased AKT signaling and cervical cancer cell proliferation.

Taken together, these data suggest that inactivation of OGDHL can contribute to cervical tumorigenesis via activation of the AKT signaling pathway and thus support it as an important anti-proliferative gene in cervical cancer.

Structure-activity relationship (SAR) study of ethyl 2-amino-6-(3,5-dimethoxyphenyl)-4-(2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate (CXL017) and the potential of the lead against multidrug resistance in cancer treatment

Multidrug resistance (MDR) against standard therapies poses a serious challenge in cancer treatment, and there is a clinical need for new anticancer agents that would selectively target MDR malignancies. Our previous studies have identified a 4H-chromene system, CXL017 (4) as an example, that can preferentially kill MDR cancer cells. To further improve its potency, we have performed detailed structure-activity relationship (SAR) studies at the 3, 4, and 6 positions of the 4H-chromene system. The results reveal that the 3 and 4 positions prefer rigid and hydrophobic functional groups while the 6 position prefers a meta or para-substituted aryl functional group and the substituent should be small and hydrophilic. We have also identified and characterized nine MDR cancer cells that acquire MDR through different mechanisms and demonstrated the scope of our new lead, 9g, to selectively target different MDR cancers, which holds promise to help manage MDR in cancer treatment.

Dietary carotenoid lutein protects against DNA damage and alterations of the redox status induced by cisplatin in human derived HepG2 cells

Several epidemiological and experimental studies has been reported that lutein (LT) presents antioxidant properties. Aim of the present study was to investigate the protective effects of LT against oxidative stress and DNA damage induced by cisplatin (cDDP) in a human derived liver cell line (HepG2). Cell viability and DNA-damage was monitored by MTT and comet assays. Moreover, different biochemical parameters related to redox status (glutathione, cytochrome-c and intracellular ROS) were also evaluated. A clear DNA-damage was seen with cDDP (1.0μM) treatment. In combination with the carotenoid, reduction of DNA damage was observed after pre- and simultaneous treatment of the cells, but not when the carotenoid was added to the cells after the exposure to cDDP. Exposure of the cells to cDDP also caused significant changes of all biochemical parameters and in co-treatment of the cells with LT, the carotenoid reverted these alterations. The results indicate that cDDP induces pronounced oxidative stress in HepG2 cells that is related to DNA damage and that the supplementation with the antioxidant LT may protect these adverse effects caused by the exposure of the cells to platinum compound, which can be a good predict for chemoprevention.

The Bcl-2/Bcl-XL inhibitor ABT-737 promotes death of retinoblastoma cancer cells

PURPOSE

Retinoblastoma is a malignant tumor that usually develops in early childhood. During retinoblastoma spreading, RB1 gene inactivation is followed by additional genomic modifications which progressively lead to resistance of tumor cells to death. Drugs that act at downstream levels of death signaling pathways should therefore be interesting in killing retinoblastoma cells. ABT-737, a BH3 mimetic molecule effective at the mitochondrial level, has been shown to induce apoptosis in different human tumoral cell lines as well as in primary patient-derived cells, and in a mouse xenograph model.

METHODS

In this report, we analyzed the pro-death effect of ABT-737 on two human retinoblastoma cell lines, Y79 and WERI-Rb, as well as on the mouse photoreceptor cell line 661W.

RESULTS

We observed that ABT-737 was very effective as a single agent in inducing human WERI-Rb cells apoptosis without affecting the mouse 661W photoreceptor cells. However human Y79 cells were resistant to ABT-737, as a probable consequence of the absence of Bax. The high sensitivity of WERI-Rb to ABT-737 can be increased by downregulating Mcl-1 using the proteasome inhibitor MG-132. Preliminary analysis in primary mouse retinoblastoma tumoral cell lines predicts high sensitivity to ABT-737.

CONCLUSION

Our data suggest that ABT-737 or related compounds could be a highly effective drug in the treatment of some retinoblastomas.

Enhancement of cyclophosphamide-induced antitumor effect by a novel polysaccharide from Ganoderma atrum in sarcoma 180-bearing mice

The aim of this study was to investigate the enhancement of Ganoderma atrum polysaccharide (PSG-1) on cyclophosphamide (CTX)-induced antitumor effect in sarcoma 180 (S-180)-bearing mice. Results showed that both CTX and PSG-1 delayed tumor growth and resulted in tumor apoptosis. The combined regimen was superior to either modality alone. Moreover, the combined treatment-induced apoptosis was mediated via mitochondrial pathway, as evidenced by alterations of Bcl-2 family proteins, loss of mitochondrial membrane potential (Δψ(m)), cytochrome c release, and caspases activation. Our results also showed that thymus and spleen indexes, lymphocytes proliferation, and concentrations of cytokine in the CTX group were decreased, which were alleviated by PSG-1. Additionally, the combined treatment ameliorated oxidative stress as compared with CTX alone. Taken together, we conclude that PSG-1 improved the antitumor effect of CTX, possibly in part mediated by enhancing the induction of apoptosis via mitochondrial pathways, activating host immune function, and modifying the redox system in S-180-bearing mice.

Blockade of electron transport during ischemia preserves bcl-2 and inhibits opening of the mitochondrial permeability transition pore

Myocardial ischemia damages the electron transport chain and augments cardiomyocyte death during reperfusion. To understand the relationship between ischemic mitochondrial damage and mitochondrial-driven cell death, the isolated perfused heart underwent global stop-flow ischemia with and without mitochondrial protection by reversible blockade of electron transport. Ischemic damage to electron transport depleted bcl-2 content and favored mitochondrial permeability transition (MPT). Reversible blockade of electron transport preserved bcl-2 content and attenuated calcium-stimulated mitochondrial swelling. Thus, the damaged electron transport chain leads to bcl-2 depletion and MPT opening. Chemical inhibition of bcl-2 with HA14-1 also dramatically increased mitochondrial swelling, augmented by exogenous H(2)O(2) stress, indicating that bcl-2 depleted mitochondria are poised to undergo MPT during the enhanced oxidative stress of reperfusion.

Role of Bcl-2 family proteins and caspases in the regulation of apoptosis

Apoptosis, or programmed cell death, plays a pivotal role in the elimination of unwanted, damaged, or infected cells in multicellular organisms and also in diverse biological processes, including development, cell differentiation, and proliferation. Apoptosis is a highly regulated form of cell death, and dysregulation of apoptosis results in pathological conditions including cancer, autoimmune and neurodegenerative diseases. The Bcl-2 family proteins are key regulators of apoptosis, which include both anti- and pro-apoptotic proteins, and a slight change in the dynamic balance of these proteins may result either in inhibition or promotion of cell death. Execution of apoptosis by various stimuli is initiated by activating either intrinsic or extrinsic pathways which lead to a series of downstream cascade of events, releasing of various apoptotic mediators from mitochondria and activation of caspases, important for the cell fate. In view of recent research advances about underlying mechanism of apoptosis, this review highlights the basics concept of apoptosis and its regulation by Bcl-2 family of protein. Furthermore, this review discusses the interplay of various apoptotic mediators and caspases to decide the fate of the cell. We expect that this review will add to the pool of basic information necessary to understand the mechanism of apoptosis which may implicate in designing better strategy to develop biomedical therapy to control apoptosis.

Apoptosis and autophagy: decoding calcium signals that mediate life or death

Calcium is a versatile and dynamic 2nd messenger that is essential for the survival of all higher organisms. In cells that undergo activation or excitation, calcium is released from the endoplasmic/sarcoplasmic reticulum to activate calcium-dependent kinases and phosphatases, thereby regulating numerous cellular processes; for example, apoptosis and autophagy. In the case of apoptosis, endogenous ligands or pharmacological agents induce prolonged cytosolic calcium elevation, which in turn leads to cell death. In contrast, there is now evidence that calcium regulates autophagy by several mechanisms, and these may be important for maintaining cell survival. Here we summarize what is known about how calcium regulates these life and death decisions. We pay particular attention to pathways that have been described in lymphocytes and cardiomyocytes, as these systems provide optimal models for understanding calcium signaling in the context of normal cell physiology.

PGC-1alpha is required for training-induced prevention of age-associated decline in mitochondrial enzymes in mouse skeletal muscle

The aim of the present study was to test the hypothesis that exercise training prevents an age-associated decline in skeletal muscle mitochondrial enzymes through a PGC-1alpha dependent mechanism. Whole body PGC-1alpha knock-out (KO) and littermate wildtype (WT) mice were submitted to long term running wheel exercise training or a sedentary lifestyle from 2 to 13 month of age. Furthermore, a group of approximately 4-month-old mice was used as young untrained controls. There was in both genotypes an age-associated approximately 30% decrease in citrate synthase (CS) activity and superoxide dismutase (SOD)2 protein content in 13-month-old untrained mice compared with young untrained mice. However, training prevented the age-associated decrease in CS activity and SOD2 protein content only in WT mice, but long term exercise training did increase HKII protein content in both genotypes. In addition, while CS activity and protein expression of cytc and SOD2 were 50-150% lower in skeletal muscle of PGC-1alpha mice than WT mice, the expression of the pro-apoptotic protein Bax and the anti-apoptotic Bcl2 was approximately 30% elevated in PGC-1alpha KO mice. In conclusion, the present findings indicate that PGC-1alpha is required for training-induced prevention of an age-associated decline in CS activity and SOD2 protein expression in skeletal muscle.

Mcl-1 is an important determinant of the apoptotic response to the BH3-mimetic molecule HA14-1 in cisplatin-resistant ovarian carcinoma cells

Chemoresistance of ovarian carcinoma has been associated previously to the absence of Bcl-x(L) expression downregulation in response to cisplatin. Among BH3-mimetic molecules constituting promising anticancer agents able to inhibit the activity of antiapoptotic Bcl-2 family proteins, we evaluated the effect of one of them, HA14-1, on various ovarian carcinoma cell lines. In response to HA14-1, the cisplatin-resistant IGROV1-R10 cell line underwent massive cell death, whereas other cell lines presented a partial response (IGROV1, SKOV3, and A2780) or did not respond to this molecule (OAW42 and OAW42-R). However, the expression of HA14-1 targets (Bcl-2 and Bcl-x(L)) did not correlate to these different responses. In contrast, cell death was associated with the disappearance of Mcl-1 after exposure to HA14-1. We showed that, in the HA14-1 nonresponsive cell lines (SKOV3 and OAW42), small interfering RNA-mediated Mcl-1 downregulation allowed HA14-1-induced massive apoptosis in the absence of chemotherapy. Furthermore, cisplatin-induced Mcl-1 downregulation was also able to sensitize highly chemoresistant SKOV3 cells to HA14-1. Taken together, these results show that Bcl-x(L) and Mcl-1 are able to cooperate to protect ovarian carcinoma cells against oncogenic stress or chemotherapy-induced apoptosis and suggest that the development of multitargeted strategies directed against these two antiapoptotic proteins may constitute a major challenge for the therapeutic care of chemoresistant ovarian carcinomas. BH3-mimetic compounds represent promising tools for this purpose either on their own (direct or indirect pan-inhibitors) or in combination with new drugs aiming to inactivate Mcl-1.

(-)-Epigallocatechin-3-gallate induces apoptosis of human hepatoma cells by mitochondrial pathways related to reactive oxygen species

The aim of this study was to investigate the effects of (-)-epigallocatechin-3-gallate (EGCG) on the induction of apoptosis in hepatocarcinoma cell lines in vitro and further examine the molecular mechanisms of EGCG-induced apoptosis. In the present study, it was observed that EGCG rapidly induced apoptosis in hepatocarcinoma SMMC7721 cells. EGCG-induced apoptosis was in association with the attenuation of mitochondrial transmembrane potentials (Deltapsi(m)), the alteration of Bcl-2 family proteins, the release of cytochrome c from mitochondria into the cytosol, and the activation of caspase-3 and caspase-9. Elevation of intracellular reactive oxygen species (ROS) production was also shown during EGCG-induced apoptosis of hepatocarcinoma SMMC7721 cells. The antioxidant N-acetyl-l-cysteine (NAC) significantly reduced ROS production and EGCG-induced apoptosis, suggesting that ROS plays a key role in EGCG-induced apoptosis in hepatocarcinoma SMMC7721 cells. In summary, EGCG-induced apoptosis through mitochondrial pathways, and ROS affected EGCG-induced apoptosis in hepatocarcinoma SMMC7721 cells.

Dual mechanisms of sHA 14-1 in inducing cell death through endoplasmic reticulum and mitochondria

HA 14-1 is a small-molecule Bcl-2 antagonist that promotes apoptosis in malignant cells, but its mechanism of action is not well defined. We recently reported that HA 14-1 has a half-life of only 15 min in vitro, which led us to develop a stable analog of HA 14-1 (sHA 14-1). The current study characterizes its mode of action. Because of the antiapoptotic function of Bcl-2 family proteins on the endoplasmic reticulum (ER) and mitochondria, the effect of sHA 14-1 on both organelles was evaluated. sHA 14-1 induced ER calcium release in human leukemic cells within 1 min, followed by induction of the ER stress-inducible transcription factor ATF4. Similar kinetics and stronger intensity of ER calcium release were induced by the sarcoendoplasmic reticulum Ca(2+)-ATPase (SERCA) inhibitor thapsigargin, accompanied by similar kinetics and intensity of ATF4 induction. sHA 14-1 directly inhibited SERCA enzymatic activity but had no effect on the inositol triphosphate receptor. Evaluation of the mitochondrial pathway showed that sHA 14-1 triggered a loss of mitochondrial transmembrane potential (Delta psi m) and weak caspase-9 activation, whereas thapsigargin had no effect. (R)-4-(3-Dimethylamino-1-phenylsulfanylmethyl-propylamino)-N-{4-[4-(4'-chloro-biphenyl-2-ylmethyl)-piperazin-1-yl]-benzoyl}-3-nitrobenzenesulfonamide (ABT-737), a well established small-molecule Bcl-2 antagonist, rapidly induced loss of Delta psi m and caspase-9 activation but had no effect on the ER. The pan-caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone had some protective effect on sHA 14-1-induced cell death. These collective results suggest a unique dual targeting mechanism of sHA 14-1 on the apoptotic resistance machinery of tumor cells that includes antiapoptotic Bcl-2 family proteins and SERCA proteins.

Exercise training inducibility of MnSOD protein expression and activity is retained while reducing prooxidant signaling in the heart of senescent rats

While the stress response to heat and exercise is limited in the heart with progressive aging, recent data indicate that acute or short-term exercise upregulates the Mn isoform of superoxide dismutase (MnSOD), which may provide protection against ischemia-reperfusion injury and cell death by reducing oxidative stress. Growing evidence indicates that inducible nitric oxide synthase (iNOS) contributes to age-induced increases in oxidative stress and risk of heart failure. We postulated that oxidative stress and iNOS levels would be related to the ability of the aging heart to upregulate MnSOD in response to long-term exercise training. Six- and twenty-seven-mo-old Fischer-344 rats had been assigned to young sedentary (YS), young exercise (YE), old sedentary (OS), or old exercise (OE) groups. ET groups ran on a treadmill for 60 min/day, 5 days/wk for a total of 12 wk. MnSOD protein expression in the left ventricle was increased (+43%) by 12 wk of exercise training in the old age group, with no changes in Cu,ZnSOD. Exercise training also increased MnSOD activity in left ventricles from old and young rats. HSP70 was inducible by exercise training in hearts exclusively from the young age group. iNOS protein expression increased markedly with aging (+548%), while exercise training decreased iNOS levels by -73% in OE compared with OS. In addition, 4-hydroxynonenal protein adducts in the left ventricle increased by 237% with aging, while 12 wk of exercise training resulted in attenuation (-55%). These data indicate that inducibility of MnSOD is preserved with long-term exercise training in the aging rat heart. Moreover, upregulation of MnSOD in the aging heart was directly associated with attenuated levels of oxidative stress, including iNOS.

Prosurvival Bcl-2 proteins stabilize pancreatic mitochondria and protect against necrosis in experimental pancreatitis

Acinar cells in pancreatitis die through apoptosis and necrosis, the roles of which are different. The severity of experimental pancreatitis correlates directly with the extent of necrosis and inversely, with apoptosis. Apoptosis is mediated by the release of cytochrome c into the cytosol followed by caspase activation, whereas necrosis is associated with the mitochondrial membrane potential (DeltaPsim) loss leading to ATP depletion. Here, we investigate the role of Bcl-2 proteins in apoptosis and necrosis in pancreatitis. We found up-regulation of prosurvival Bcl-2 proteins in pancreas in various experimental models of acute pancreatitis, most pronounced for Bcl-xL. This up-regulation translated into increased levels of Bcl-xL and Bcl-2 in pancreatic mitochondria. Bcl-xL/Bcl-2 inhibitors induced DeltaPsim loss and cytochrome c release in isolated mitochondria. Corroborating the results on mitochondria, Bcl-xL/Bcl-2 inhibitors induced DeltaPsim loss, ATP depletion and necrosis in pancreatic acinar cells, both untreated and hyperstimulated with CCK-8 (in vitro pancreatitis model). Together Bcl-xL/Bcl-2 inhibitors and CCK induced more necrosis than either treatment alone. Bcl-xL/Bcl-2 inhibitors also stimulated cytochrome c release in acinar cells leading to caspase-3 activation and apoptosis. However, different from their effect on pronecrotic signals, the stimulation by Bcl-xL/Bcl-2 inhibitors of apoptotic responses was less in CCK-treated than control cells. Therefore, Bcl-xL/Bcl-2 inhibitors potentiated CCK-induced necrosis but not apoptosis. Correspondingly, transfection with Bcl-xL siRNA stimulated necrosis but not apoptosis in the in vitro pancreatitis model. Further, in animal models of pancreatitis Bcl-xL up-regulation inversely correlated with necrosis, but not apoptosis. Results indicate that Bcl-xL and Bcl-2 protect acinar cells from necrosis in pancreatitis by stabilizing mitochondria against death signals. We conclude that Bcl-xL/Bcl-2 inhibition would aggravate acute pancreatitis, whereas Bcl-xL/Bcl-2 up-regulation presents a strategy to prevent or attenuate necrosis in pancreatitis.

The Bcl-2 antagonist HA14-1 forms a fluorescent albumin complex that can be mistaken for several oxidized ROS probes

The proapoptotic effects of the Bcl-2 antagonist HA14-1 are believed to derive from its affinity for the hydrophobic groove on Bcl-2 and Bcl-x(L), thereby displacing proapoptotic factors, e.g. Bax and Bak. We have reported that HA14-1 promotes the efficacy of low-dose photodynamic therapy (PDT). A recent report proposed that the proapoptotic activity of HA14-1 reflects its ability to generate reactive oxygen species (ROS) when incubated in an aqueous environment. This later study, like several other HA14-1 investigations, relied on the use of fluorescent probes for ROS detection. We found that HA14-1 reacts with the albumin in serum to yield a fluorescent product. After correcting for this effect, the putative formation of ROS by HA14-1 could not be demonstrated with the fluorescent probes H(2)DCFDA, dihydroethidium or dihydrorhodamine. Indeed, the fluorescence excitation/emission spectra of HA14-1 encompassed the excitation/emission wavelengths used to detect these ROS probes. Cells cultured in a medium supplemented with ovalbumin, instead of serum, underwent apoptosis following HA14-1 addition, but did not exhibit fluorescence. Hence, HA14-1 fluorescence was unrelated to its proapoptotic activity. We conclude that the enhancement of PDT by HA14-1 reflects a pharmacologic effect, rather than its direct contribution of ROS.

Bcl-2 protein family members: versatile regulators of calcium signaling in cell survival and apoptosis

Bcl-2 family members are important regulators of cell survival and cell death. Researchers have focused mainly on mitochondria, where both proapoptotic and antiapoptotic family members function to regulate the release of cytochrome c and other mediators of apoptosis. However, as reviewed here, Bcl-2 family members also operate on another front, the endoplasmic reticulum (ER), to both positively and negatively regulate the release of Ca2+. There is abundant evidence that Ca2+ signals trigger apoptosis in response to a wide variety of agents and conditions. Conversely, Ca2+ signals can also mediate cell survival. Recent findings indicate that Bcl-2 interacts with inositol 1,4,5-trisphosphate (IP3) receptor Ca2+ channels on the ER, regulating their opening in response to IP3- and thus inhibiting IP3-mediated Ca2+ signals that induce apoptosis while enhancing Ca2+ signals that support cell survival.

Structure-related clustering of gene expression fingerprints of thp-1 cells exposed to smaller polycyclic aromatic hydrocarbons

This study was undertaken to test the hypothesis that structurally similar PAHs induce similar gene expression profiles. THP-1 cells were exposed to a series of 12 selected PAHs at 50 microM for 24 hours and gene expressions profiles were analyzed using both unsupervised and supervised methods. Clustering analysis of gene expression profiles revealed that the 12 tested chemicals were grouped into five clusters. Within each cluster, the gene expression profiles are more similar to each other than to the ones outside the cluster. One-methylanthracene and 1-methylfluorene were found to have the most similar profiles; dibenzothiophene and dibenzofuran were found to share common profiles with fluorine. As expression pattern comparisons were expanded, similarity in genomic fingerprint dropped off dramatically. Prediction analysis of microarrays (PAM) based on the clustering pattern generated 49 predictor genes that can be used for sample discrimination. Moreover, a significant analysis of Microarrays (SAM) identified 598 genes being modulated by tested chemicals with a variety of biological processes, such as cell cycle, metabolism, and protein binding and KEGG pathways being significantly (p < 0.05) affected. It is feasible to distinguish structurally different PAHs based on their genomic fingerprints, which are mechanism based.

Combined proteasome and Bcl-2 inhibition stimulates apoptosis and inhibits growth in EBV-transformed lymphocytes: a potential therapeutic approach to EBV-associated lymphoproliferative diseases

OBJECTIVES

Epstein-Barr virus (EBV) transforms B-cells into immortalized lymphoblastoid cells (LCLs) by triggering signaling pathways that lead to activation of multiple transcription factors and anti-apoptotic proteins, including NF-kappaB and Bcl-2, respectively. Since proteasome inhibition suppresses NF-kappaB activity, we sought to determine whether the proteasome inhibitor, bortezomib, alone or in combination with Bcl-2 inhibition, has potential as a therapeutic strategy in EBV-driven B-cell neoplasms.

METHODS

We evaluated the effects of bortezomib in LCLs in vitro, in the presence and absence of the small molecular inhibitor of Bcl-2, HA14-1, on proliferation, apoptosis, caspase activation, and expression of Bcl-2 family members, and in vivo in the severe combined immunodeficiency (SCID) model of EBV+ lymphoproliferative disease.

RESULTS

Bortezomib inhibited proliferation, stimulated apoptosis, and activated caspases-3 and -9 in a dose-dependent manner in LCLs. In vivo, bortezomib completely abrogated development of EBV+ lymphoproliferative disease in LCL-bearing SCID mice. When HA14-1 was added to bortezomib in vitro, we observed a synergistic anti-proliferative effect and enhancement of apoptosis and caspase activation, including activation of caspase-8, in LCLs. These events were associated with modulation of expression of Bcl-2 family members towards a pro-apoptotic profile with translocation of cytochrome C from mitochondria to cytoplasm.

CONCLUSIONS

These studies demonstrated that bortezomib mediates anti-tumor effects in EBV-associated lymphoproliferations both in vitro and in vivo, and that its anti-proliferative and apoptotic effects are synergistically enhanced in the presence of a Bcl-2 inhibitor. These findings support further investigation of bortezomib in EBV+ lymphoproliferative diseases, and suggest that bortezomib in combination with Bcl-2 antagonists represents a potential therapeutic strategy for EBV-driven B-cell neoplasms.

Overcoming apoptosis deficiency of melanoma-hope for new therapeutic approaches

The increased incidence of malignant melanoma in the last decades, its high mortality and pronounced therapy resistance pose an enormous challenge. Important therapeutic targets for melanoma are the induction of apoptosis and suppression of survival pathways. Preclinical studies have demonstrated the efficacy of pro-apoptotic Bcl-2 proteins and of death receptor ligands to trigger apoptosis in melanoma cells. In the clinical setting, BH3 domain mimics and death receptor agonists are therefore considered as promising, specific novel treatments to add to the conventional pro-apoptotic strategies such as chemo- or radiotherapy. However, constitutively activated survival pathways, in particular the mitogen-activated protein kinases, protein kinase B/Akt and nuclear factor (NF)-kappaB, all may work in concert to prevent effective therapy. Thus, selective biologicals developed with the aim to inhibit pro-survival signaling are currently tested in melanoma. For highly therapy-resistant tumors such as melanoma, development of novel drug combinations will be essential, and combinations of survival inhibitors and pro-apoptotic mediators appear most promising. The challenge of the near future will be to make a rational choice of the multiple possible combinations and protocols. This review gives a critical overview of proteins involved in melanoma chemoresistance, which are targets for current drug development leading to the best choice for future trials.

Bcl-2 inhibitors induce apoptosis in chronic lymphocytic leukemia cells

OBJECTIVE

Antiapoptotic Bcl-2 is overexpressed in most cases of chronic lymphocytic leukemia (CLL). The inhibition of the antiapoptotic Bcl-2 proteins is an attractive strategy for either restoring normal apoptotic process in cancer cells or making these cells more susceptible to conventional chemotherapy. We studied the effect of Bcl-2 inhibitors on the viability of cells from CLL and other mature B-cell neoplasms.

MATERIALS AND METHODS

We studied the cytotoxic effects of four nonpeptidic cell-permeable Bcl-2 inhibitors (HA14-1, antimycin A, GX15-003, and GX15-070) on B cells from patients with CLL, mantle cell lymphoma (MCL), and splenic marginal zone lymphoma (SMZL). Moreover, we analyzed the effect of these inhibitors in combination with fludarabine or chlorambucil.

RESULTS

HA14-1 induced apoptosis with an EC50 lower than 50 microM in 26 of the 36 CLL samples analyzed. The mean EC50 for these sensitive patients was 23 +/- 2 microM. Antimycin A induced apoptosis in 13 of the 18 CLL samples analyzed. Both HA14-1 and antimycin A induced cytochrome c release from mitochondria and caspase-3 activation. Moreover, HA14-1 induced apoptosis in peripheral cells from MCL and SMZL. HA14-1 also induced apoptosis in CLL samples with alterations in p53 or ATM. Finally, GX compounds induced apoptosis in B cells from 9 of the 11 CLL samples tested. The combination of either HA14-1, antimycin A, or GX compounds with fludarabine or chlorambucil had additive cytotoxic effects on CLL cells.

CONCLUSION

Bcl-2 inhibitors induce apoptosis in CLL cells ex vivo and could be used in CLL as monotherapy or given in combination with current chemotherapy.