The involvement of mitochondria and the caspase-9 activation pathway in rituximab-induced apoptosis in FL cells

Relationship between BCL2 mutations and follicular lymphoma outcome in the chemoimmunotherapy era

How to identify follicular lymphoma (FL) patients with low disease burden but high risk for early progression is unclear. Building on a prior study demonstrating the early transformation of FLs with high variant allele frequency (VAF) BCL2 mutations at activation-induced cytidine deaminase (AICDA) sites, we examined 11 AICDA mutational targets, including BCL2, BCL6, PAX5, PIM1, RHOH, SOCS, and MYC, in 199 newly diagnosed grade 1 and 2 FLs. BCL2 mutations with VAF ≥20% occurred in 52% of cases. Among 97 FL patients who did not initially receive rituximab-containing therapy, nonsynonymous BCL2 mutations at VAF ≥20% were associated with increased transformation risk (HR 3.01, 95% CI 1.04-8.78, p = 0.043) and a trend toward shorter event-free survival (EFS, median 20 months with mutations versus 54 months without, p = 0.052). Other sequenced genes were less frequently mutated and did not increase the prognostic value of the panel. Across the entire population, nonsynonymous BCL2 mutations at VAF ≥20% were associated with decreased EFS (HR 1.55, 95% CI 1.02-2.35, p = 0.043 after correction for FLIPI and treatment) and decreased overall survival after median 14-year follow-up (HR 1.82, 95% CI 1.05-3.17, p = 0.034). Thus, high VAF nonsynonymous BCL2 mutations remain prognostic even in the chemoimmunotherapy era.

Has PdCu@GO effect on oxidant/antioxidant balance? Using zebrafish embryos and larvae as a model

Industrial products containing PdCu@GO can gain access to the aquaculture environment, causing dangerous effects on living biota. In this study, the developmental toxicity of zebrafish treated with different concentrations (50, 100, 250, 500 and 1000 μg/L) of PdCu@GO was investigated. The findings showed that PdCu@GO administration decreased the hatchability and survival rate, caused dose-dependent cardiac malformation. Reactive oxygen species (ROS) and apoptosis were also inhibited in a dose-dependent manner, with acetylcholinesterase (AChE) activity affected by nano-Pd exposure. As evidence for oxidative stress, malondialdehyde (MDA) level increased and superoxide dismutase (SOD), catalase (CAT) glutathione peroxidase (GPx) activities and glutathione (GSH) level decreased due to the increase in PdCu@GO concentration. Our research, it was determined that the oxidative stress stimulated by the increase in the concentration of PdCu@GO in zebrafish caused apoptosis (Caspase-3) and DNA damage (8-OHdG). Stimulation of ROS, inflammatory cytokines, tumor Necrosis Factor Alfa (TNF-α) and interleukin - 6 (IL-6), which act as signaling molecules to trigger proinflammatory cytokine production, induced zebrafish immunotoxicity. However, it was determined that the increase of ROS induced teratogenicity through the induction of nuclear factor erythroid 2 level (Nrf-2), NF-κB and apoptotic signaling pathways triggered by oxidative stress. Taken together with the research findings, the study contributed to a comprehensive assessment of the toxicological profile of PdCu@GO by investigating the effects on zebrafish embryonic development and potential molecular mechanisms.

Structure Elucidation of 16 Undescribed Steroidal Glycosides from the Underground Parts of Agapanthus africanus and Apoptosis-Inducing Activity in Small-Cell Lung Cancer Cell

To explore new candidates for anticancer agents from natural products, the underground parts of Agapanthus africanus, commonly used as an ornamental plant, were investigated phytochemically. As a result, 16 undescribed steroidal glycosides (1-16) were obtained, and their structures were determined mainly by NMR spectroscopic analysis and chemical transformations. The cytotoxic activities of the isolated compounds (1-16) against SBC-3 human small-cell lung cancer cells, A549 human adenocarcinoma cells, and HL-60 human promyelocytic leukemia cells were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2-tetrazolium bromide (MTT) assay. Compound 1, a bisdesmosidic furostanol glycoside, and 10, a bisdesmosidic spirostanol glycoside, were cytotoxic to all three cell lines with IC₅₀ values ranging from 1.2 to 13 μM. As 1 exhibited the most potent cytotoxicity against SBC-3 cells among the isolated compounds, its apoptosis-inducing activity toward SBC-3 cells was examined. Compound 1 arrested SBC-3 cells at the G₂/M phase of the cell cycle and effectively induced apoptosis via an intrinsic pathway accompanied by the dissipation of membrane potential and morphological changes in mitochondria.

Novel Oleanane-Type Triterpene Glycosides from the Saponaria officinalis L. Seeds and Apoptosis-Inducing Activity via Mitochondria

Saponaria officinalis L., commonly known as “Soapwort”, is a rich source of triterpene glycosides; however, the chemical constituents of S. officinalis seeds have not been fully identified. In this study, we conducted a systematic phytochemical investigation of the seeds of S. officinalis and obtained 17 oleanane-type triterpene glycosides (1–17), including seven new glycosides (1–7). The structures of 1–7 were determined based on a detailed analysis of NMR spectroscopic data and chromatographic and spectroscopic analyses following specific chemical transformation. The cytotoxicities of the isolated compounds were evaluated against HL-60 human promyelocytic leukemia cells, A549 human adenocarcinoma lung cancer cells, and SBC-3 human small-cell lung cancer cells. The cytotoxicities of 1, 4, and 10 toward HL-60 cells and SBC-3 cells were nearly as potent as that of cisplatin. Compound 1, a bisdesmosidic triterpene glycoside obtained in good yield, arrested the cell cycle of SBC-3 cells at the G₂/M phase, and induced apoptosis through an intrinsic pathway, accompanied by ROS generation. As a result of the mitochondrial dysfunction induced by 1, mitochondria selective autophagy, termed mitophagy, occurred in SBC-3 cells.

Trispecific CD19-CD20-CD22-targeting duoCAR-T cells eliminate antigen-heterogeneous B cell tumors in preclinical models

A substantial number of patients with leukemia and lymphoma treated with anti-CD19 or anti-CD22 monoCAR-T cell therapy relapse because of antigen loss or down-regulation. We hypothesized that B cell tumor antigen escape may be overcome by a chimeric antigen receptor (CAR) design that simultaneously targets three B cell leukemia antigens. We engineered trispecific duoCAR-T cells with lentiviral vectors encoding two CAR open reading frames that target CD19, CD20, and CD22. The duoCARs were composed of a CAR with a tandem CD19- and CD20-targeting binder, linked by the P2A self-cleaving peptide to a second CAR targeting CD22. Multiple combinations of intracellular T cell signaling motifs were evaluated. The most potent duoCAR architectures included those with ICOS, OX40, or CD27 signaling domains rather than those from CD28 or 4-1BB. We identified four optimal binder and signaling combinations that potently rejected xenografted leukemia and lymphoma tumors in vivo. Moreover, in mice bearing a mixture of B cell lymphoma lines composed of parental triple-positive cells, CD19-negative, CD20-negative, and CD22-negative variants, only the trispecific duoCAR-T cells rapidly and efficiently rejected the tumors. Each of the monoCAR-T cells failed to prevent tumor progression. Analysis of intracellular signaling profiles demonstrates that the distinct signaling of the intracellular domains used may contribute to these differential effects. Multispecific duoCAR-T cells are a promising strategy to prevent antigen loss-mediated relapse or the down-regulation of target antigen in patients with B cell malignancies.

Genotoxicity induced by hexavalent chromium leading to eryptosis in Ctenopharyngodon idellus

The initiation of eryptosis as a result of genotoxic action of Cr(VI), seen through micronucleus and comet assay in the peripheral erythrocytes of Ctenopharyngodon idellus was evaluated through RT-qPCR. For this, fish was exposed to sublethal concentration of hexavalent chromium (5.30 and 10.63 mg/L), and the blood was sampled on different endpoints (15, 30 and 45 days). Accumulation of chromium in the erythrocytes was also studied, which depicted a significant increase in toxicant concentration and time dependent manner. Both concentrations of hexavalent chromium induced DNA damage, visible in the form of comet tails. The presence of micronuclei in the erythrocytes was accompanied with occurrence of nuclear bud (NBu), lobed nucleus (Lb), notched nucleus (Nt), vacuolated nucleus (Vn), binucleated cell (Bn) as nuclear abnormalities; and acanthocytes (Ac), echinocytes (Ec), notched cells (Nc), microcytes (Mc) and vacuolated cytoplasm (Vc) as cytoplasmic abnormalities. The expression of genes related to intrinsic apoptotic pathway induced by Cr(VI) presented significant (p < 0.05) upregulation in the expression of p53, Bax, Apaf-1, caspase9 and caspase3, and downregulation of Bcl2; inferring the initiation of apoptotic pathway. The ration of Bax and Bcl2 also appended the apoptotic state of the erythrocytes. From the present investigation, it can be concluded that genotoxicity induced by hexavalent chromium lead to eryptosis in C. idellus.

Effect of acute exposure of triazophos on histological structure and apoptosis of the brain and liver of zebrafish (Danio rerio)

Triazophos (TAP) has become a part of widespread pollutant of the aquatic environment due to its residue. Current study was designed to investigate the toxic effect of TAP at different doses (0.06, 0.3 and 1.5 mg/L) to the model organism of zebrafish (Danio rerio) by using multi-endpoint analysis in a 96 h acute exposure test. The direct observation that histological and ultrastructural alteration of zebrafish brain and liver were carried out via paraffin section in hematoxylin and eosin (H&E) staining and transmission electron microscopy (TEM), respectively. In addition, a series of methods were applied for exploring the physiological parameters related to cellular apoptosis. Results indicated that vacuolar structure after 96 h treatment with TAP were appeared in the molecular and granular layers of cerebellum. A large number of nuclear retraction, tissues vacuolation and cytoplasmic loss were observed in liver at histological level. From the fine structural level, the mitochondrial vacuolation and membrane damage of brain cells were found and the cristae of mitochondria disintegrated partly in hepatocytes. Onset of such histological structure alterations were one of the most intuitive reflection to TAP exposure, which needs to analyze biochemical alterations for further study. The mitochondrial membrane potential (MMP) showed a downward trend in the brain and liver of zebrafish. Simultaneously, the activity of caspase-3 and caspase-9 increased after 96 h exposure with a concentration-dependent manner, which could be served as a suitable indicator of cellular apoptosis. Furthermore, apoptosis-related genes (Apaf-1, p53, Bax, Bcl-2, caspase-3 and caspase-9) transcription showed different alterations in response to the TAP treatment. These results indicated that TAP exposure led to apoptosis in zebrafish brain and liver and it was speculated that the apoptosis may occur through mitochondrial pathway. The present study demonstrated that the exposure of zebrafish to the insecticide TAP led to observe its effects at both histological structure and apoptosis level in liver and brain.

In vitro cytotoxicity and anticancer effects of citral nanostructured lipid carrier on MDA MBA-231 human breast cancer cells

Very recently, we postulated that the incorporation of citral into nanostructured lipid carrier (NLC-Citral) improves solubility and delivery of the citral without toxic effects in vivo. Thus, the objective of this study is to evaluate anti-cancer effects of NLC-Citral in MDA MB-231 cells in vitro through the Annexin V, cell cycle, JC-1 and fluorometric assays. Additionally, this study is aimed to effects of NLC-Citral in reducing the tumor weight and size in 4T1 induced murine breast cancer model. Results showed that NLC-Citral induced apoptosis and G2/M arrest in MDA MB-231 cells. Furthermore, a prominent anti-metastatic ability of NLC-Citral was demonstrated in vitro using scratch, migration and invasion assays. A significant reduction of migrated and invaded cells was observed in the NLC-Citral treated MDA MB-231 cells. To further evaluate the apoptotic and anti-metastatic mechanism of NLC-Citral at the molecular level, microarray-based gene expression and proteomic profiling were conducted. Based on the result obtained, NLC-Citral was found to regulate several important signaling pathways related to cancer development such as apoptosis, cell cycle, and metastasis signaling pathways. Additionally, gene expression analysis was validated through the targeted RNA sequencing and real-time polymerase chain reaction. In conclusion, the NLC-Citral inhibited the proliferation of breast cancer cells in vitro, majorly through the induction of apoptosis, anti-metastasis, anti-angiogenesis potentials, and reducing the tumor weight and size without altering the therapeutic effects of citral.

An in vivo analysis of Cr6+ induced biochemical, genotoxicological and transcriptional profiling of genes related to oxidative stress, DNA damage and apoptosis in liver of fish, Channa punctatus (Bloch, 1793)

Present study was designed to assess the hexavalent chromium (Cr⁶⁺) mediated oxidative stress that induces DNA damage and apoptosis in adult fish, Channa punctatus (35 ± 3.0 g; 14.5 ± 1.0 cm; Actinopterygii). Fishes were maintained in three groups for 15, 30 and 45 d of exposure periods. They were treated with 5% (Group T1) and 10% (Group T2) of 96 h-LC₅₀ of chromium trioxide (Cr⁶⁺). Controls were run for the similar duration. A significant (p < 0.05) increment in the activities of antioxidant enzymes, SOD and CAT in liver tissues of the exposed fish evinces the persistence of oxidative stress. A significant (p < 0.05) increase in induction of micronuclei (MN) coupled with transcriptional responses of target genes related to antioxidant enzymes, DNA damage and apoptosis (sod, cat, gsr, nox-1, p53, bax, bcl-2, apaf-1 and casp3a) establishes the impact of oxidative stress due to in vivo, Cr⁶⁺ accumulation in liver as compared to control (0 mg/L), in a dose and exposure-dependent manner. Initially, the increased level of reactive oxygen species (ROS) in liver coincided with that of enhanced mRNA expression of antioxidant enzymes, sod, cat, gsr and nox-1 but, later, the overproduction of ROS, after 45 d of exposure of Cr⁶⁺, resulted in a significant (p < 0.05) up-regulation of p53. Our findings also unveil that the up-regulation of bax, apaf-1 and casp3a and down-regulation of bcl-2 are associated with Cr⁶⁺-induced oxidative stress mediated-apoptosis in liver of test fish. Aforesaid molecular markers can, thus, be efficiently utilized for bio-monitoring of aquatic regimes and conservation of fish biodiversity.

Cellular mechanism of resistance of human colorectal adenocarcinoma cells against apoptosis-induction by Russell's Viper venom l-amino acid oxidase (Rusvinoxidase)

The present study highlights the cellular mechanism of resistance in human adenocarcinoma (Colo-205) cells against apoptosis induction by Rusvinoxidase, an l-amino acid oxidase purified from Russell's Viper venom (RVV). The significantly lower cytotoxicity as well as apoptotic activity of Rusvinoxidase towards Colo-205 cells (compared to MCF-7 breast cancer cells) is correlated with lower depletion of cellular glutathione content and increased down-regulation of catalase activity of Colo-205 cells following Rusvinoxidase treatment. Exposure to Rusvinoxidase subsequently diminished reactive oxygen species (ROS) production and failed to impair mitochondrial membrane potential, resulting in apoptosis induction resistance in Colo-205 cells. Further, higher expression levels of caspase 8, compared to caspase 9, indicate that Rusvinoxidase preferentially triggers the extrinsic pathway of apoptosis in Colo-205 cells. A time-dependent lower ratio of the relative expression of Bax and Bcl-xL (pro- and anti-apoptotic proteins) in Colo-205 cells, compared to our previous study on MCF-7 cells, unambiguously supports a higher cellular resistance mechanism in Colo-205 cells against Rusvinoxidase-induced apoptosis.

Selective scavenging of intra-mitochondrial superoxide corrects diclofenac-induced mitochondrial dysfunction and gastric injury: A novel gastroprotective mechanism independent of gastric acid suppression

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used to treat multiple inflammatory diseases and pain but severe gastric mucosal damage is the worst outcome of NSAID-therapy. Here we report that mitoTEMPO, a mitochondrially targeted superoxide (O₂^-) scavenger protected as well as healed gastric injury induced by diclofenac (DCF), the most commonly used NSAID. Common existing therapy against gastric injury involves suppression of gastric acid secretion by proton pump inhibitors and histamine H₂ receptor antagonists; however, dyspepsia, vitamin B12 deficiency and gastric microfloral dysbalance are the major drawbacks of acid suppression. Interestingly, mitoTEMPO did not inhibit gastric acid secretion but offered gastroprotection by preventing DCF-induced generation of O₂^- due to mitochondrial respiratory chain failure and by preventing mitochondrial oxidative stress (MOS)-mediated mitopathology. MitoTEMPO even restored DCF-stimulated reduced fatty acid oxidation, mitochondrial depolarization and bioenergetic crisis in gastric mucosa. MitoTEMPO also prevented the activation of mitochondrial pathway of apoptosis and MOS-mediated proinflammatory signaling through NF-κB by DCF. Furthermore, mitoTEMPO when administered in rats with preformed gastric lesions expedited the healing of gastric injury and the healed stomach exhibited its normal physiology as evident from gastric acid and pepsin secretions under basal or stimulated conditions. Thus, in contrast to the existing antiulcer drugs, mitochondrially targeted O₂^- scavengers like mitoTEMPO may represent a novel class of gastroprotective molecules that does not affect gastric acid secretion and may be used in combination with DCF, keeping its anti-inflammatory action intact, while reducing its gastrodamaging effects.

Rituximab: modes of action, remaining dispute and future perspective

Less than two decades ago, immunotherapy joined chemotherapy and radiotherapy as an effective approach for the treatment of cancer. The anti-CD20 monoclonal antibody, rituximab, is now used to treat almost all types of non-Hodgkin's B-cell lymphomas, and it could be useful in the treatment of other diseases with B-cell involvement. Upon binding, rituximab induces death of the target cells. It seems to act not only by activating immune system defense mechanisms such as complement-dependent and antibody-dependent cellular cytotoxicity, but also by inducing direct cell death. In this paper, we review current knowledge on rituximab mechanisms of action, with particular attention to its direct effects, and also highlight potential future avenues of research.

Action and resistance of monoclonal CD20 antibodies therapy in B-cell Non-Hodgkin Lymphomas

Anti-CD20 monoclonal antibodies (mAbs) have improved patient's survival with Non-Hodgkin Lymphoma, when combined with chemotherapy. Several mechanisms of action have been reported, including antibody-dependent cellular cytotoxicity, complement-dependent cytotoxicity and induction of apoptosis. Despite the large amount of studies and published data, the role each mechanism played in vivo is not fully understood. Furthermore, the reason why a significant percentage of patients are refractory or resistant remains unknown. Several activated intracellular signaling pathways have been implicated in the mechanisms of resistance of rituximab. In the present manuscript, we review those mechanisms and new anti-CD20 mAbs, as well as the efforts being accomplished to overcome it, focusing on new drugs targeting pathways implicated in resistance to rituximab.

Rituximab increases the cytotoxicities of vincristine and hydroxyurea through caspase-dependent and caspase-independent cell death, respectively

In the treatment of B cell non-Hodgkin's lymphoma, rituximab is used in combination with different chemotherapeutics to improve its efficacy, but the mechanisms involved are not fully understood. The authors examined the mechanism by which rituximab combined with hydroxyurea or vincristine induces cell death in the human Burkitt's lymphoma Ramos cell line. Cell death was analyzed by phosphatidylserine exposure, caspase activation, and mitochondrial membrane changes. Their results indicate that the cell death initiated by the combination of rituximab and hydroxyurea is caspase-independent. In contrast, preincubation of the cells with the same concentrations of caspase inhibitors used with hydroxyurea eliminated the synergistic effect of the rituximab and vincristine combination. This was confirmed by the presence of the active fragment of caspase-3 in vincristine-treated cells. These preliminary results demonstrate that rituximab can activate different downstream signals to induce direct cell effects. Furthermore, the findings support the important role of mitochondria in the regulation of both pathways.

Rituximab-induced early and late signaling have opposite effects on dexamethasone-induced apoptosis in human follicular lymphoma cells

The addition of rituximab (RTX) to standard chemotherapy has improved the treatment of B-cell malignancies. We show here that RTX and dexamethasone (Dex) induced synergistic apoptosis in follicular lymphoma cell lines. However, apoptosis was delayed by RTX-induced early protective signaling. RTX-induced early signaling also decreased Dex-induced apoptosis and led to phosphorylation of ERK1/2, Bcl-2 (at serine 70) and phosphorylation/degradation of BimL/EL. All these events were prevented by the MEK inhibitor, UO126. Therefore, we suggest that RTX-induced ERK-mediated signaling events lead to protection from apoptosis during early signaling and that blocking of Bim and Bcl-2 phosphorylation might be used as a novel strategy for lymphoma treatment.

Canonical and new generation anticancer drugs also target energy metabolism

Significant efforts have been made for the development of new anticancer drugs (protein kinase or proteasome inhibitors, monoclonal humanized antibodies) with presumably low or negligible side effects and high specificity. However, an in-depth analysis of the side effects of several currently used canonical (platin-based drugs, taxanes, anthracyclines, etoposides, antimetabolites) and new generation anticancer drugs as the first line of clinical treatment reveals significant perturbation of glycolysis and oxidative phosphorylation. Canonical and new generation drug side effects include decreased (1) intracellular ATP levels, (2) glycolytic/mitochondrial enzyme/transporter activities and/or (3) mitochondrial electrical membrane potentials. Furthermore, the anti-proliferative effects of these drugs are markedly attenuated in tumor rho (0) cells, in which functional mitochondria are absent; in addition, several anticancer drugs directly interact with isolated mitochondria affecting their functions. Therefore, several anticancer drugs also target the energy metabolism, and hence, the documented inhibitory effect of anticancer drugs on cancer growth should also be linked to the blocking of ATP supply pathways. These often overlooked effects of canonical and new generation anticancer drugs emphasize the role of energy metabolism in maintaining cancer cells viable and its targeting as a complementary and successful strategy for cancer treatment.

Increased 8-hydroxy-2'-deoxyguanosine in plasma and decreased mRNA expression of human 8-oxoguanine DNA glycosylase 1, anti-oxidant enzymes, mitochondrial biogenesis-related proteins and glycolytic enzymes in leucocytes in patients with systemic lupus erythematosus

We measured plasma levels of the oxidative DNA damage marker 8-hydroxy-2'-deoxyguanosine (8-OHdG) and leucocyte mRNA expression levels of the genes encoding the 8-OHdG repair enzyme human 8-oxoguanine DNA glycosylase 1 (hOGG1), the anti-oxidant enzymes copper/zinc superoxide dismutase (Cu/ZnSOD), manganese superoxide dismutase (MnSOD), catalase, glutathione peroxidase-1 (GPx-1), GPx-4, glutathione reductase (GR) and glutathione synthetase (GS), the mitochondrial biogenesis-related proteins mtDNA-encoded ND 1 polypeptide (ND1), ND6, ATPase 6, mitochondrial transcription factor A (Tfam), nuclear respiratory factor 1(NRF-1), pyruvate dehydrogenase E1 component alpha subunit (PDHA1), pyruvate dehydrogenase kinase isoenzyme 1 (PDK-1) and hypoxia inducible factor-1α (HIF-1α) and the glycolytic enzymes hexokinase-II (HK-II), glucose 6-phosphate isomerase (GPI), phosphofructokinase (PFK), glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and lactate dehydrogenase A (LDHa). We analysed their relevance to oxidative damage in 85 systemic lupus erythematosus (SLE) patients, four complicated SLE patients undergoing rituximab treatment and 45 healthy individuals. SLE patients had higher plasma 8-OHdG levels (P < 0·01) but lower leucocyte expression of the genes encoding hOGG1(P < 0·01), anti-oxidant enzymes (P < 0·05), mitochondrial biogenesis-related proteins (P < 0·05) and glycolytic enzymes (P < 0·05) than healthy individuals. The increase in plasma 8-OHdG was correlated positively with the elevation of leucocyte expression of the genes encoding hOGG1 (P < 0·05), anti-oxidant enzymes (P < 0·05), several mitochondrial biogenesis-related proteins (P < 0·05) and glycolytic enzymes (P < 0·05) in lupus patients. The patients, whose leucocyte mtDNA harboured D310 heteroplasmy, exhibited a positive correlation between the mtDNA copy number and expression of ND1, ND6 and ATPase 6 (P < 0·05) and a negative correlation between mtDNA copy number and systemic lupus erythematosus disease activity index (SLEDAI) (P < 0·05), as well as plasma 8-OHdG (P < 0·05). In particular, four complicated SLE patients with increased expression of the genes encoding the anti-oxidant enzymes, GAPDH, Tfam and PDHA1, experienced better therapeutic outcomes after rituximab therapy. In conclusion, higher oxidative damage with suboptimal increases in DNA repair, anti-oxidant capacity, mitochondrial biogenesis and glucose metabolism may be implicated in SLE deterioration, and this impairment might be improved by targeted biological therapy.

Celastrol induces apoptosis in gefitinib-resistant non-small cell lung cancer cells via caspases-dependent pathways and Hsp90 client protein degradation

Celastrol, a triterpene extracted from the Chinese herb Tripterygium wilfordii, has been shown to have multiple bioactivities. Although among these activities, its anti-cancer effects have attracted the most attention, the effect of celastrol on gefitinib-resistant non-small cell lung cancer (NSCLC) cells is not clearly known. Here, we examined the potency of celastrol in three different NSCLC cell lines. We explored its treatment mechanism in two gefitinib-resistant NSCLC cell lines (H1650 and H1975). Our data demonstrated that celastrol exerted its apoptotic effect in a dose- and time-dependent manner. Also, the mitochondria membrane potential was gradually lost and the ratio of Bax/Bcl-2 increased after the treatment of celastrol, both of which are indicators of mitochondria membrane integrity. Although the caspases were activated, the treatment with pan-caspase inhibitor could partially inhibit the level of apoptosis. Moreover, the protein level of Hsp90 client proteins, EGFR and AKT, was measured. Interestingly, both client proteins were remarkably down-regulated after the treatment of celastrol. Taken together, our data showed that celastrol may be developed as a promising agent for treating gefitinib-resistant NSCLCs by inducing apoptosis through caspase-dependent pathways and Hsp90 client protein degradation.

Cd-induced apoptosis through the mitochondrial pathway in the hepatopancreas of the freshwater crab Sinopotamon henanense

Cd is one of the most common pollutants in the environment that also induces the apoptosis. To explore the mechanism of apoptosis in the hepatopancreas, freshwater crab S. henanense were treated with 0, 3.56, 7.12, 14.25, 28.49 and 56.98 mg/L Cd for 72 h. Apoptosis was noticeable in every treatment group and necrosis was observed clearly in the high concentration Cd groups. Classical apoptotic bodies were found by transmission electronic microscopy, which revealed chromatin condensation under nuclear membrane and mitochondrial membrane rupture. An increasing number of autolysosomes, damaged rough endoplamic reticulum and Golgi complex were observed as the Cd concentration increase. Brown colored apoptotic cells were detected by the TUNEL test in all Cd-treatment groups. The apoptosis index increased following the elevation of Cd concentration and got 32.9% in the highest Cd group. Caspase-9 and caspase-3 activities increased in the lower Cd treatment groups but no changes in the higher Cd concentration groups (comparing to the control group). The activity of caspase-8 did not change significantly. No significant change in the content of mitochondrial cytochrome c (cyt c) in Cd exposed groups except the decrease in the 56.98 mg/L group. In crabs treated with 3.56, 7.12 and 14.25 mg/L Cd, hyperpolarization of mitochondrial membrane potential (Δψ_m) significantly increased. These results implied that apoptosis in the hepatopancreas induced by Cd occurrs through the mitochondrial caspase-dependent pathway. However, whether there are other apoptotic pathways needs to be studied further.

Copper induces apoptotic cell death through reactive oxygen species-triggered oxidative stress in the intertidal copepod Tigriopus japonicus

The copepod, Tigriopus japonicus is an important model for toxicity testing. However, no attempt has been made in analyzing the effect of toxicants at the level of the ROS-mediated signal transduction pathway. To understand copper-induced cytotoxicity at the molecular level, we employed several cellular and biochemical assays after exposure to copper, and found a significant induction of enzyme activities of antioxidant proteins with increased intracellular reactive oxygen species (ROS) as well as an increase of TUNEL-positive cells, but a decrease of BrdU-positive cells. In addition, several important genes such as p38 MAPK, antioxidant-related genes, Hsps, and apoptosis-related genes were significantly modulated by copper exposure. Taken together, we suggest that copper-induced cytotoxicity is mediated by the formation of intracellular ROS and oxidative stress in T. japonicus. Whole body biochemical assays such as TUNEL- and BrdU-assay will provide a better understanding of cellular responses such as apoptosis and cell death upon cytotoxic exposure of copper in T. japonicus.

Direct Effect of Rituximab in B-Cell–Derived Lymphoid Neoplasias: Mechanism, Regulation, and Perspectives

The anti-CD20 monoclonal antibody rituximab is the backbone of treatment for the B-cell malignancies non-Hodgkin lymphoma and chronic lymphocytic leukemia. However, there is a wide variability in response to rituximab treatment, and some patients are refractory to current standard therapies. Rituximab kills B cells by multiple mechanisms of action, including complement-dependent cytotoxicity and antibody-dependent cellular cytotoxicity, which are immune-mediated mechanisms, as well as by direct effects on cell signaling pathways and cell membranes following CD20 binding. A large number of events that are affected by rituximab binding have been identified, including lipid raft modifications, kinase and caspase activation, and effects on transcription factors and apoptotic/antiapoptotic molecules. Studies on cell lines and isolated tumor cells have shown that by targeting these pathways, it may be possible to increase or decrease susceptibility to rituximab cell killing. An increased understanding of the direct effects of rituximab may therefore aid in the design of new, rational combinations to improve the outcome of CD20-based therapy for patients who currently have suboptimal outcome following standard treatments. Mol Cancer Res; 9(11); 1435–42. ©2011 AACR.

Mitochondrial pathway of apoptosis in the hepatopancreas of the freshwater crab Sinopotamon yangtsekiense exposed to cadmium

Cadmium (Cd) is one of the most common toxic metals in water. To investigate the mechanism of Cd-induced apoptosis in the hepatopancreas, freshwater crabs Sinopotamon yangtsekiense were exposed to 0, 3.56, 7.12, 14.25, 28.49 and 56.98 mg/L Cd for 48 h. After a 48 h exposure, apoptosis and necroptosis were apparent in the group exposed to 28.49 mg/L Cd and only one case of necrosis was observed in the highest concentration of Cd. Electronic microscopy revealed chromatin condensation under nuclear membrane and mitochondrial membrane rupture in 14.25 and 28.49 mg/L Cd treatment groups. Brown colored apoptotic cells were detected with the TUNEL test in all Cd-treatment groups. The AI in 56.98 mg/L group was 1.4-fold greater than that in crabs exposed to 14.25mg/L Cd. Caspase-9, caspase-3, SDH and Ca(2+)-ATPase activities increased with increasing Cd concentration. However, the activities of caspase-8 and LDH did not change significantly compared with control group. These results implied that Cd induced apoptosis in the hepatopancreas occurs through a mitochondrial pathway.

Safrole induces apoptosis in human oral cancer HSC-3 cells

Phytochemicals have been used as potential chemopreventive or chemotherapeutic agents. However, there are data suggesting a mutagenic effect of some phytochemicals. We hypothesized that safrole would have anticancer effects on human oral squamous cell carcinoma HSC-3 cells. Safrole decreased the percentage of viable HSC-3 cells via induction of apoptosis by an increased level of cytosolic Ca(2+) and a reduction in the mitochondrial membrane potential (ΔΨ(m)). Changes in the membrane potential were associated with changes in the Bax, release of cytochrome c from mitochondria, and activation of downstream caspases-9 and -3, resulting in apoptotic cell death. In vivo studies also showed that safrole reduced the size and volume of an HSC-3 solid tumor on a xenograft athymic nu/nu mouse model. Western blotting and flow cytometric analysis studies confirmed that safrole-mediated apoptotic cell death of HSC-3 cells is regulated by cytosolic Ca(2+) and by mitochondria- and Fas-dependent pathways.

Caspase 3a: new prognostic marker for diffuse large B-cell lymphoma in the rituximab era

Fewer than half of patients with diffuse large B-cell lymphoma (DLBCL) can be cured. Molecular prognostic factors in the rituximab era must be re-evaluated, because there are few molecular indicators with prognostic value. Samples of DLBCL from 41 newly diagnosed patients with a median follow-up of 52 months were studied. Immunohistochemical staining was performed to investigate the expression of apoptosis-related proteins (Bcl-2 and caspase 3a), cell proliferation (Ki-67), and tumor microenvironmental factors. Two groups were analysed, 23 cases (56%) treated with CHOP and 18 (44%) treated with R-CHOP. Survival analysis showed that cases with overexpression of Bcl-2 had worse overall survival (OS) in the CHOP group. However, OS in the R-CHOP group was adversely affected by lack of caspase 3a staining. In the entire series, cases positive for caspase 3a showed significantly better OS, without significance for other parameters, and caspase 3 was associated with parameters of prognosis and OS in R-CHOP. This is the first study that relates caspase 3a and prognosis in DLBCL.

Lysosomal-mitochondrial axis in zoledronic acid-induced apoptosis in human follicular lymphoma cells

Bisphosphonates (BPs) are potent inhibitors of osteoclast function, widely used to treat excessive bone resorption associated with bone metastases, that also have anti-tumor activity. Zoledronic acid (ZOL) represents a potential chemotherapeutic agent for the treatment of cancer. ZOL is the most potent nitrogen-containing BPs, and it inhibits cell growth and induces apoptosis in a variety of cancer cells. Recently we demonstrated that accumulation of isopentenyl pyrophosphate and the consequent formation of a new type of ATP analog (ApppI) after mevalonate pathway inhibition by nitrogen-containing BPs strongly correlates with ZOL-induced cell death in cancer cells in vitro. In this study we show that ZOL-induced apoptosis in HF28RA human follicular lymphoma cells occurs exclusively via the mitochondrial pathway, involves lysosomes, and is dependent on mevalonate pathway inhibition. To define the exact signaling pathway connecting them, we used modified HF28RA cell lines overexpressing either BclXL or dominant-negative caspase-9. In both mutant cells, mitochondrial and lysosomal membrane permeabilization (MMP and LMP) were totally prevented, indicating signaling between lysosomes and mitochondria and, additionally, an amplification loop for MMP and/or LMP regulated by caspase-9 in association with farnesyl pyrophosphate synthetase inhibition. Additionally, the lysosomal pathway in ZOL-induced apoptosis plays an additional/amplification role of the intrinsic pathway independently of caspase-3 activation. Moreover, we show a potential regulation by Bcl-XL and caspase-9 on cell cycle regulators of S-phase. Our findings provide a molecular basis for new strategies concomitantly targeting cell death pathways from multiple sites.

Anti-CD20 monoclonal antibodies: historical and future perspectives

Antibodies to CD20 have confirmed the hypothesis that monoclonal reagents can be given in vivo to alleviate human diseases. The targeting of CD20 on normal, malignant and auto-immune B-lymphocytes by rituximab has demonstrated substantial benefits for patients with a variety of B-cell lymphomas, as well as some with autoimmune disorders. There has been a notable increase in the survival rates from B-cell lymphoma in the decade since anti-CD20 therapy was introduced.

The synthesized 2-(2-fluorophenyl)-6,7-methylenedioxyquinolin-4-one (CHM-1) promoted G2/M arrest through inhibition of CDK1 and induced apoptosis through the mitochondrial-dependent pathway in CT-26 murine colorectal adenocarcinoma cells

BACKGROUND

In this study, we investigated the effects of 2-(2-fluorophenyl)-6,7-methylenedioxyquinolin-4-one (CHM-1) on cell viability, cell cycle arrest and apoptosis in CT-26 murine colorectal adenocarcinoma cells.

METHODS

For determining cell viability, the MTT assay was used. CHM-1 promoted G2/M arrest by PI staining and flow cytometric analysis. Apoptotic cells were evaluated by DAPI staining. We used CDK1 kinase assay, Western blot analysis and caspase activity assays for examining the CDK1 activity and proteins correlated with apoptosis and cell cycle arrest. The in vivo anti-tumor effects of CHM-1-P were evaluated in BALB/c mice inoculated with CT-26 cells orthotopic model.

RESULTS

CHM-1 induced CT-26 cell viability inhibition and morphologic changes in a dose-dependent and time-dependent manner and the approximate IC50 was 742.36 nM. CHM-1 induced significant G2/M arrest and apoptosis in CT-26 cells. CHM-1 inhibited the CDK1 activity and decreased CDK1, Cyclin A, Cyclin B protein levels. CHM-1 induced apoptosis in CT-26 cells and promoted increasing of cytosolic cytochrome c, AIF, Bax, BAD, cleavage of pro-caspase-9, and -3. The significant reduction of caspase-9 and -3 activity and increasing the viable CT-26 cells after pretreated with caspase-9 and -3 inhibitor indicated that CHM-1-induced apoptosis was mainly mediated a mitochondria-dependent pathway. CHM-1-P improved mice survival rate, and enlargement of the spleen and liver metastasis were significantly reduced in groups treated with either 10 mg/kg and 30 mg/kg of CHM-1-P and 5-FU in comparison to these of CT-26/BALB/c mice.

CONCLUSIONS

Taken together, CHM-1 acted against colorectal adenocarcinoma cells in vitro via G2/M arrest and apoptosis, and CHM-1-P inhibited tumor growth in vivo.

Feedback regulation of mitochondria by caspase-9 in the B cell receptor-mediated apoptosis

During the germinal centre reaction (GC), B cells with non-functional or self-reactive antigen receptors are negatively selected by apoptosis to generate B cell repertoire with appropriate antigen specificities. We studied the molecular mechanism of Fas/CD95- and B cell receptor (BCR)-induced apoptosis to shed light on the signalling events involved in the negative selection of GC B cells. As an experimental model, we used human follicular lymphoma (FL) cell line HF1A3, which originates from a GC B cell, and transfected HF1A3 cell lines overexpressing Bcl-x(L), c-FLIP(long) or dominant negative (DN) caspase-9. Fas-induced apoptosis was dependent on the caspase-8 activation, since the overexpression of c-FLIP(long), a natural inhibitor of caspase-8 activation, blocked apoptosis induced by Fas. In contrast, caspase-9 activation was not involved in Fas-induced apoptosis. BCR-induced apoptosis showed the typical characteristics of mitochondria-dependent (intrinsic) apoptosis. Firstly, the activation of caspase-9 was involved in BCR-induced DNA fragmentation, while caspase-8 showed only marginal role. Secondly, overexpression of Bcl-x(L) could block all apoptotic changes induced by BCR. As a novel finding, we demonstrate that caspase-9 can enhance the cytochrome-c release and collapse of mitochondrial membrane potential (DeltaPsi(m)) during BCR-induced apoptosis. The requirement of different signalling pathways in apoptosis induced by BCR and Fas may be relevant, since Fas- and BCR-induced apoptosis can thus be regulated independently, and targeted to different subsets of GC B cells.