Disruption of mitochondrial membrane potential during apoptosis induced by PSC 833 and CsA in multidrug-resistant lymphoid leukemia

Apoptosis Due to After-effects of Acute Ethanol Exposure in Brain Cortex: Intrinsic and Extrinsic Signaling Pathways

Alcohol hangover is the combination of negative mental and physical symptoms which can be experienced after a single episode of alcohol consumption, starting when blood alcohol concentration approaches zero. We previously demonstrated that hangover provokes mitochondrial dysfunction, oxidative stress, imbalance in antioxidant defenses, and impairment in cellular bioenergetics. Chronic and acute ethanol intake induces neuroapoptosis but there are no studies which evaluated apoptosis at alcohol hangover. The aim of the present work was to study alcohol residual effects on intrinsic and extrinsic apoptotic signaling pathways in mice brain cortex. Male Swiss mice received i.p. injection of ethanol (3.8 g/kg) or saline. Six hours after injection, at alcohol hangover onset, mitochondria and tissue lysates were obtained from brain cortex. Results indicated that during alcohol hangover a loss of granularity of mitochondria and a strong increment in mitochondrial permeability were observed, indicating the occurrence of swelling. Alcohol-treated mice showed a significant 35% increase in Bax/Bcl-2 ratio and a 5-fold increase in the ratio level of cytochrome c between mitochondria and cytosol. Caspase 3, 8 and 9 protein expressions were 32%, 33% and 20% respectively enhanced and the activity of caspase 3 and 6 was 30% and 20% increased also due to the hangover condition. Moreover, 38% and 32% increments were found in PARP1 and p53 protein expression respectively and on the contrary, SIRT-1 was almost 50% lower than controls due to the hangover condition. The present work demonstrates that alcohol after-effects could result in the activation of mitochondrial and non-mitochondrial apoptosis pathways.

Low mitochondrial DNA copy number induces chemotherapy resistance via epithelial-mesenchymal transition by DNA methylation in esophageal squamous cancer cells

Background

Esophageal squamous cell carcinoma (ESCC) is one of the most severe cancers and is characterized by chemotherapy resistance and poor prognosis associated with epithelial-mesenchymal transition (EMT). In a previous study, a low mitochondrial DNA (mtDNA) copy number was associated with poorer prognosis and induced EMT in ESCC. However, the detailed mechanism related to mtDNA copy number and EMT is unclear. The aim of this study was to clarify the mechanism by which a change in mtDNA copy number contributes to EMT and to examine treatment of chemotherapy resistance in ESCC.

Methods

The association between low mtDNA copy number and chemotherapy resistance was investigated using specimens from 88 patients who underwent surgery after neoadjuvant chemotherapy. Then, the mtDNA content of human ESCC cell lines, TE8 and TE11, was depleted by knockdown of mitochondrial transcription factor A expression. The present study focused on modulation of mitochondrial membrane potential (MMP) and DNA methylation as the mechanisms by which mtDNA copy number affects EMT. mRNA and protein expression, chemotherapy sensitivity, proliferation, MMP and DNA methylation were evaluated, and in vitro and in vivo assays were conducted to clarify these mechanisms.

Results

ESCC patients with decreased mtDNA copy number who underwent R0 resection after neoadjuvant chemotherapy had significantly worse pathological response and recurrence-free survival. Additionally, low mtDNA copy number was associated with resistance to chemotherapy in vitro and in vivo. mtDNA controlled MMP, and MMP depolarization induced EMT. Depletion of mtDNA and low MMP induced DNA methylation via a DNA methylation transcription factor (DNMT), and a DNMT inhibitor suppressed EMT and improved chemotherapy sensitivity in mtDNA-depleted ESCC cells, as shown by in vitro and in vivo assays.

Conclusion

This study showed that decreased mtDNA copy number induced EMT via modulation of MMP and DNA methylation in ESCC. Therapeutic strategies increasing mtDNA copy number and DNMT inhibitors may be effective in preventing EMT and chemosensitivity resistance.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03594-2.

Siomycin A induces reactive oxygen species-mediated cytotoxicity in ovarian cancer cells

Ovarian cancer is one of the leading causes of cancer-related death among women worldwide and accounts for 4% of all cancer cases in female patients. To date, ovarian cancer has the poorest prognosis among all types of gynecological cancer; thus, it is necessary to identify prospective therapeutic options. Previous studies have demonstrated the involvement of reactive oxygen species (ROS) in the cytotoxicity of various anticancer drugs against several types of carcinoma, including ovarian cancer. The present study aimed to investigate the anticancer effects of Siomycin A, a thiopeptide antibiotic, on the ovarian cancer cell lines PA1 and OVCAR3. To determine the viability of these cells following exposure to Siomycin A, the MTT assay was used, and apoptosis was determined by ELISA. In addition, mitochondrial membrane potential was determined by JC1 staining, and cellular ROS levels were assessed by dichlorodihydrofluorescein diacetate staining in the presence and absence of antioxidant NAC. The subsequent levels of antioxidant enzymes and glutathione were also determined following Siomycin A treatment in the two cell lines. A combination study with Siomycin A and cisplatin indicated enhanced efficiency of the drugs on ovarian cancer cell viability. The results of the present study also demonstrated that Siomycin A induced ROS production, inhibited the major antioxidant enzymes, including catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase and intracellular GSH in PA1 and OVCAR3 cells, and inhibited the cell viability with an IC₅₀ of ~5.0 and 2.5 µM after 72 h respectively compared with the untreated controls. Additionally, the Siomycin A-induced ROS production further targeted apoptotic cell death by impairing the mitochondrial membrane potential and modulating the levels of pro- and antiapoptotic proteins compared with those in the corresponding control groups. The administration of the antioxidant N-acetylcysteine significantly abrogated the cytotoxic effects of Siomycin A. In conclusion, the results of the present study demonstrated the role of ROS in Siomycin A-mediated cytotoxicity in ovarian cancer cells.

P38-β/SAPK-inhibiting and apoptosis-inducing activities of (E)-4-chloro-2-((3-ethoxy-2-hydroxybenzylidene) amino)phenol

The present study has three purposes; first evaluating cytotoxicity of (E)-4-chloro-2-((3-ethoxy-2-hydroxybenzylidene)amino)phenol (ACES), second deciphering ACES-mediated cellular death mechanism, and third estimating ACES-mediated alterations in the expressions of mitogen-activated protein kinase (MAPK) pathway-related genes. Neutral red uptake assay, cell cycle analysis, mitochondrial membrane potential (MMP), reactive oxygen species (ROS) measurements, caspase 3/7 and 9 activations, and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) were implemented. IC₅₀ values of ACES-treated five cells were around 4-6 µg/mL. However, Caco-2 and Huh-7 cells were found to be twofold resistant and fivefold sensitive with IC₅₀ values of 11 µg/mL and 0.93 µg/mL, respectively. In this study, it was initially reported that ACES exhibits selective cytotoxicity to Huh-7 cells. In addition, ACES induced apoptosis by nuclear fragmentation, MMP disruption, and intracellular ROS elevation in MCF-7 cells. qRT-PCR experiment indicated the expressions of 30 genes including ATF2, CREB1, MYC, NFATC4 (NFAT3), CCNA1, CCNB1, CCND2, CDK2, CDKN1A (p21CIP1), CDKN1C (p57KIP2), CDKN2A (p16INK4a), CDKN2B (p15INK4b), DLK1, NRAS, CDC42, PAK1, MAP4K1 (HPK1), MAP3K3 (MEKK3), MAP2K3 (MEK3), MAP2K6 (MEK6), MOS, MAPK1 (ERK2), MAPK8 (JNK1), MAPK10 (JNK3), MAPK11 (p38-β), LAMTOR3 (MP1), MAPK8IP2 (JIP-1), PRDX6 (AOP2), COL1A1, and HSPA5 (Grp78) were downregulated at least 1.5-fold. Moreover, ACES effectively inhibited expressions of genes that code for elements of p38-β/stress-activated protein kinase (SAPK) pathway. ACES has the potential to be used for the reversal of trastuzumab resistance in breast cancer patients by inhibiting p38/SAPK pathway in MCF-7 cells. Therefore, with the selective cytotoxic, apoptosis-inducing, and p38-β/SAPK-inhibiting activities, ACES can be utilized for developing a novel anticancer drug.

Effects of Immunosuppressive Medications on Mitochondrial Function

BACKGROUND

Immunosuppressive medications are widely used for the prevention of allograft rejection in transplantation and graft-versus-host disease after allogeneic hematopoietic stem cell transplantation. Despite their clinical utility, these medications are accompanied by multiple off-target effects, some of which may be mediated by their effects on mitochondria.

METHODS

We examined the effect of commonly used immunosuppressive reagents, mycophenolate mofetil (MMF), cyclosporine A (CsA), rapamycin, and tacrolimus on mitochondrial function in human T-cells. T-cells were cultured in the presence of immunosuppressive medications in a range of therapeutic doses. After incubation, mitochondrial membrane potential, reactive oxygen species (ROS) production, and apoptotic cell death were measured by flow cytometry after staining with DiOC6, MitoSOX Red, and Annexin V and 7-AAD, respectively. Increases in cytosolic cytochrome c were demonstrated by Western blot. T-cell basal oxygen consumption rates were measured using a Seahorse bioanalyzer.

RESULTS

T-cells demonstrated significant levels of mitochondrial depolarization after treatment with therapeutic levels of MMF but not after treatment with CsA, tacrolimus, or rapamycin. Only MMF induced T-cell ROS production and induced significant levels of apoptotic cell death that were associated with increased levels of cytosolic cytochrome c. MMF decreased T-cell basal oxygen consumption within its therapeutic range, and CsA demonstrated a trend toward this result.

CONCLUSIONS

The impairment of mitochondrial function by commonly used immunosuppressive reagents may impair T-cell differentiation and function by decreasing energy production, producing toxic ROS, and inducing apoptotic cell death.

Ketamine treatment affects hippocampal but not cortical mitochondrial function in prepubertal rats

Previous reports have shown that ketamine triggered apoptosis in immature developing brain involving mitochondrial-mediated pathways. However, no data for ketamine effects on hippocampal and cortical mitochondrial function are available in prepubertal rats. Twenty-one-day-old Sprague-Dawley rats received ketamine (40 mg/kg i.p.) for 3 days and were killed 24 hr after the last injection. Hippocampal mitochondria from ketamine-treated rats showed decreased malate-glutamate state 4 and 3 respiratory rates and an inhibition in complex I and IV activities. Hippocampal mitochondrial membrane depolarization and mitochondrial permeability transition induction were observed. This was not reflected in an increment of H₂ O₂ production probably due to increased Mn-SOD and catalase activities, 24 hr after treatment. Interestingly, increased H₂ O₂ production rates and cardiolipin oxidation were found in hippocampal mitochondria shortly after ketamine treatment (45 min). Unlike the hippocampus, ketamine did not affect mitochondrial parameters in the brain cortex, being the area less vulnerable to suffer ketamine-induced oxidative damage. Results provide evidences that exposure of prepubertal rats to ketamine leads to an induction of mitochondrial ROS generation at early stages of treatment that was normalized by the triggering of antioxidant systems. Although hippocampal mitochondria from prepubertal rats were capable of responding to the oxidative stress, they remain partially dysfunctional.

Design, One Pot Synthesis and Molecular Docking Studies of Substituted-1H-Pyrido[2,1-b] Quinazolines as Apoptosis-Inducing Anticancer Agents

Objective:

The present study focused to build pyridine and quinazoline rings in a single molecule and designed a new fused Pyrido[2,1-b] quinazoline to have a better pharmacological activity.

Material and Methods:

A three component, one-pot synthesis of substituted-1H-Pyrido[2,1-b] quinazoline derivatives has been described by conventional and microwave synthesis using triflic acid as catalyst. These compounds were screened for in vitro cytotoxic activity against the panel of cancer cell lines A549, NCI-H460, HT-29, HCT-15, DU-145, and HFL.

Results:

Among the tested compounds, 11-(1-benzyl-1H-indol-3-y1)-2, 3, 4, 11-tetrahydro-1H-pyrido[2,1-b] quinazoline (4i) showed most potent cytotoxicity against A549 and NCI-H460 lung cancer cell lines with IC₅₀ values 4.57±0.25 and 5.53±0.49 µM, respectively. Moreover, compound 4i was found to be most potent considerable cell growth inhibition with GI₅₀ values of 2.70±0.18 and 3.24±0.40 µM against A549 and NCI-H460 cell lines, respectively. In addition, induction of apoptosis for compound 4i on A549 was investigated by morphological changes, Acridine orange/ethidium bromide (AO/EB) and DAPI staining. Furthermore, a strong anti-clonogenic effect of compound 4i on lung cancer cells was observed. The flow cytometric analysis investigation reveals that compound 4i arrests the A549 cancer cell lines at the G0/G1 phase of the cell cycle. Molecular docking were also performed on 4i, 4j, and erlotinib to predict the binding mode towards the EGFR kinase (PDB code: 1M17) and the compounds have displayed similar interactions and compared with erlotinib.

Conclusion:

Overall, these findings could suggest that the compound 4i would be an ideal lead as an anticancer agent.

Parameritannin A-2 from Urceola huaitingii enhances doxorubicin-induced mitochondria-dependent apoptosis by inhibiting the PI3K/Akt, ERK1/2 and p38 pathways in gastric cancer cells

Parameritannin A-2 (PA-2) is a natural product extracted from the stems of the plant Urceola huaitingii. Our previous studies have shown that PA-2 exhibits significant synergistic anticancer effects with doxorubicin (DOX) in HGC27 gastric cancer cell lines. Here we report that our isobolographic analysis confirms the synergistic cytotoxic effects of PA-2 and DOX in HGC27 cells. Flow cytometry and immunoblotting indicate that PA-2 enhances DOX-mediated apoptosis. Importantly, PA-2 enhances the intracellular accumulation of DOX in HGC27 cells. The combination of DOX and PA-2 remarkably increases the release of cytochrome C and the activation of caspase-3 and caspase-9, compared with DOX treatment alone. Moreover, PA-2 attenuates the DOX-induced activation of Akt, ERK1/2 and p38 signaling pathways, providing a molecular mechanism for the synergistic effects of DOX and PA-2 in the induction of apoptosis. In conclusion, our studies demonstrate that PA-2 and DOX synergistically induce mitochondria-dependent apoptosis as PA-2 inhibits the PI3K/Akt, ERK1/2 and p38 pathways in HGC27 cells. These findings suggest that the combination treatment with PA-2 and DOX may represent a potent therapy for gastric cancer.

Rhodium(iii) complexes with isoquinoline derivatives as potential anticancer agents: in vitro and in vivo activity studies

Two rhodium complexes Rh1 and Rh2 with isoquinoline derivatives were synthesized and characterized.

Machine learning for predicting lifespan-extending chemical compounds

Increasing age is a risk factor for many diseases; therefore developing pharmacological interventions that slow down ageing and consequently postpone the onset of many age-related diseases is highly desirable. In this work we analyse data from the DrugAge database, which contains chemical compounds and their effect on the lifespan of model organisms. Predictive models were built using the machine learning method random forests to predict whether or not a chemical compound will increase Caenorhabditis elegans' lifespan, using as features Gene Ontology (GO) terms annotated for proteins targeted by the compounds and chemical descriptors calculated from each compound's chemical structure. The model with the best predictive accuracy used both biological and chemical features, achieving a prediction accuracy of 80%. The top 20 most important GO terms include those related to mitochondrial processes, to enzymatic and immunological processes, and terms related to metabolic and transport processes. We applied our best model to predict compounds which are more likely to increase C. elegans' lifespan in the DGIdb database, where the effect of the compounds on an organism's lifespan is unknown. The top hit compounds can be broadly divided into four groups: compounds affecting mitochondria, compounds for cancer treatment, anti-inflammatories, and compounds for gonadotropin-releasing hormone therapies.

Human mesenchymal stromal cells undergo apoptosis and fragmentation after intravenous application in immune-competent mice

BACKGROUND AIMS

The biodistribution of human MSCs after systemic delivery is incompletely understood. We investigated the changes in cell size and cell surface markers of human MSCs after intravenous (IV) injection in immune competent mice.

METHODS

Male human MSCs were labeled with fluorescent vital dye PKH67 and tracked after IV administration in C57/BL6 mice. MSCs were tracked in blood and different murine tissues by human SRY gene quantitative polymerase chain reaction (qPCR) analysis, flow cytometry and fluorescence microscopy. Calibrated microbeads were used to track the size of transplanted MSCs.

RESULTS

The majority of injected MSCs were detected by qPCR in the lungs 5 min after transplantation, whereas <0.1% were detected in other tissues over 24 h. Flow cytometric and fluorescence microscopic analysis indicated that MSCs continuously decreased in size after transplantation and underwent fragmentation. The majority of PKH⁺ MSCs and their fragments were found in lungs and liver. PKH⁺ MSCs rapidly became positive for annexin V, propidium iodide and calreticulin, indicating loss of cell integrity. In addition, PKH⁺ fragments co-stained with antibodies against C3b, F4/80 and/or GR-1 indicating opsonization. Preincubation of MSCs in hyperosmolaric hydroxyethyl starch (HyperHAES) decreased MSCs size before transplantation, delayed the loss of viability markers and increased the frequency of traceable MSCs up to 24 h after transplantation.

CONCLUSIONS

PKH67 labeled MSCs are fragmented after IV injection in mice, acquire apoptotic and phagocytic cell markers and accumulate in the lungs and liver.

Berberine Regulated Lipid Metabolism in the Presence of C75, Compound C, and TOFA in Breast Cancer Cell Line MCF-7

Berberine interfering with cancer reprogramming metabolism was confirmed in our previous study. Lipid metabolism and mitochondrial function were also the core parts in reprogramming metabolism. In the presence of some energy-related inhibitors, including C75, compound C, and TOFA, the discrete roles of berberine in lipid metabolism and mitochondrial function were elucidated. An altered lipid metabolism induced by berberine was observed under the inhibition of FASN, AMPK, and ACC in breast cancer cell MCF-7. And the reversion of berberine-induced lipid suppression indicated that ACC inhibition might be involved in that process instead of FASN inhibition. A robust apoptosis induced by berberine even under the inhibition of AMPK and lipid synthesis was also indicated. Finally, mitochondrial function regulation under the inhibition of AMPK and ACC might be in an ACL-independent manner. Undoubtedly, the detailed mechanisms of berberine interfering with lipid metabolism and mitochondrial function combined with energy-related inhibitors need further investigation, including the potential compensatory mechanisms for ATP production and the upregulation of ACL.

Antiproliferative and apoptotic activities of extracts of Asclepias subulata

CONTEXT

Asclepias subulata Decne. (Apocynaceae) is a shrub used in the Mexican traditional medicine for the treatment of cancer.

OBJECTIVE

The objective of this study was to evaluate the antiproliferative activity of methanol extract of aerial parts of A. subulata and its fractions against different cancer cell lines. Additionally, we analyzed the mechanism of action of the active fractions.

MATERIALS AND METHODS

Methanol extract fractions were prepared by serial extraction with n-hexane, ethyl acetate, and ethanol. The antiproliferative activity of methanol extract and its fractions was evaluated, against several murine (M12.C3.F6, RAW 264.7, and L929) and human (HeLa, A549, PC-3, LS 180, and ARPE-19) cell lines by the MTT assay, using concentrations of 0.4-400 µg/mL for 48 h. Ethanol and residual fractions were separated using silica gel column. Apoptosis induction of cancer cells was evaluated by Annexin and JC-1 staining using flow cytometry.

RESULTS

Methanol extract and its fractions showed antiproliferative activity against all human cancer cell lines tested. Methanol extract had the highest antiproliferative activity on A549 and HeLa cells (IC50 values < 0.4 and 8.7 µg/mL, respectively). Ethanol and residual fractions exerted significant antiproliferative effect on A549 (IC50 < 0.4 µg/mL) and PC3 cells (IC50 1.4 and 5.1 µg/mL). Apoptotic assays showed that CEF7, CEF9, CRF6, and CRF5 fractions induced mitochondrial depolarization in A549 cells, 70, 73, 77, and 80%, respectively. Those fractions triggered the apoptosis mitochondrial pathway.

CONCLUSION

Our data show that A. subulata extracts have potent antiproliferative properties on human cancer cell lines. This plant should be considered an important source of potent anticancer compounds.

Ellagic acid induces apoptosis in TSGH8301 human bladder cancer cells through the endoplasmic reticulum stress- and mitochondria-dependent signaling pathways

To investigate the effects of ellagic acid on the growth inhibition of TSGH8301 human bladder cancer cells in vitro, cells were incubated with various doses of ellagic acid for different time periods. The phase-contrast microscope was used for examining and photographing the morphological changes in TSGH8301 cells. Flow cytometric assay was used to measure the percentage of viable cells, cell cycle distribution, apoptotic cells, ROS, mitochondrial membrane potential (ΔΨm), Ca(2+) , caspase-9 and -3 activities in TSGH8301 cells after exposure to ellagic acid. Western blotting was used to examine the changes of cell cycle and apoptosis associated proteins levels. Results indicated that ellagic acid induced morphological changes, decreased the percentage of viable cells through the induction of G0/G1 phase arrest and apoptosis, and also showed that ellagic acid promoted ROS and Ca(2+) productions and decreased the level of ΔΨm and promoted activities of caspase-9 and -3. The induction of apoptosis also confirmed by annexin V staining, comet assay, DAPI staining and DNA gel electrophoresis showed that ellagic acid induced apoptosis and DNA damage in TSGH8301 cells. Western blotting assay showed that ellagic acid promoted p21, p53 and decreased CDC2 and WEE1 for leading to G0/G1 phase arrest and promoting BAD expression, AIF and Endo G, cytochrome c, caspase-9 and -3 for leading to apoptosis in TSGH8301 cells. On the basis of these observations, we suggest that ellagic acid induced cytotoxic effects for causing a decrease in the percentage of viable cells via G0/G1 phase arrest and induction of apoptosis in TSGH8301 cells.

Toxicogenomics-based identification of mechanisms for direct immunotoxicity

Compounds with direct immunotoxic properties, including metals, mycotoxins, agricultural pesticides, and industrial chemicals, form potential human health risks due to exposure through food, drinking water, and the environment. Insights into the mechanisms of action are currently lacking for the majority of these direct immunotoxicants. Therefore, the present work aimed to gain insights into the molecular mechanisms underlying direct immunotoxicity. To this end, we assessed in vitro the effects of 31 test compounds on the transcriptome of the human Jurkat T-cell line. These compounds included direct immunotoxicants, immunosuppressive drugs with different mode of actions, and nonimmunotoxic control chemicals. Pathway analysis of the microarray data allowed us to identify canonical pathways and Gene Ontology processes that were transcriptionally regulated in common by immunotoxicants (1) with structural similarities, such as tributyltin chloride and tributyltin oxide that activated the retinoic acid/X receptor signaling pathway and (2) without structural similarities, such as As2O3, dibutyltin chloride, diazinon, MeHg, ochratoxin A (OTA), S9-treated OTA, S9-treated cyclophosphamide, and S9-treated benzo[a]pyrene, which activated unfolded protein response, and FTY720, lindane, and propanil, which activated the cholesterol biosynthesis pathway. In addition, processes uniquely affected by individual immunotoxicants were identified, such as the induction of Notch receptor signaling and the downregulation of acute-phase response genes by OTA. These findings were validated by quantitative real-time PCR analysis of genes involved in these processes. Our study indicated that diverse modes of action are involved in direct immunotoxicity and that a set of pathways or genes, rather than one single gene, can be used to screen compounds for direct immunotoxicity.

Phenethyl isothiocyanate triggers apoptosis in human malignant melanoma A375.S2 cells through reactive oxygen species and the mitochondria-dependent pathways

We have reported previously that phenethyl isothiocyanate (PEITC) induces apoptosis in human osteosarcoma U-2 OS cells. Cytotoxic activity of PEITC towards other cancer cells such as human malignant melanoma and skin cancer cells has not been reported. In this study, the anticancer activity of PEITC towards human malignant melanoma cancer A375.S2 cells was investigated. To determine the mechanisms of PEITC inhibition of cell growth, the following end points were determined in A375.S2 cells: cell morphological changes, cell cycle arrest, DNA damage and fragmentation assays and morphological assessment of nuclear change, reactive oxygen species (ROS) and Ca(2+) generations, mitochondrial membrane potential disruption, and nitric oxide and 10-N-nonyl acridine orange productions, expression and activation of caspase-3 and -9, B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax), Bcl-2, poly (adenosine diphosphate-ribose) polymerase, and cytochrome c release, apoptosis-inducing factor and endonuclease G. PEITC induced morphological changes in time- and dose-dependent manner. PEITC induced G2/M phase arrest and induced apoptosis via endoplasmic reticulum stress-mediated mitochondria-dependent pathway. Western blot analysis showed that PEITC promoted Bax expression and inhibited Bcl-2 expression associated with the disintegration of the outer mitochondrial membrane causing cytochrome c release, and activation of caspase-9 and -3 cascade leading to apoptosis. We conclude that PEITC-triggered apoptotic death in A375.S2 cells occurs through ROS-mediated mitochondria-dependent pathways.

Caffeic acid phenylethyl ester and MG132, two novel nonconventional chemotherapeutic agents, induce apoptosis of human leukemic cells by disrupting mitochondrial function

The ability to modulate balance between cell survival and death is recognized for its great therapeutic potential. Therefore, research continues to focus on elucidation of cell machinery and signaling pathways that control cell proliferation and apoptosis. Conventional chemotherapeutic agents often have a cytostatic effect over tumor cells. New natural or synthetic chemotherapeutic agents have a wider spectrum of interesting antitumor activities that merit in-depth studies. In the present work, we aimed at characterizing the molecular mechanism leading to induction of cell death upon treatment of the lymphoblastoid cell line PL104 with caffeic acid phenylethyl ester (CAPE), MG132 and two conventional chemotherapeutic agents, doxorubicine (DOX) and vincristine (VCR). Our results showed several apoptotic hallmarks such as phosphatidylserine (PS) exposure on the outer leaflet of the cell membrane, nuclear fragmentation, and increase sub-G1 DNA content after all treatments. In addition, all four drugs downregulated survivin expression. CAPE and both chemotherapeutic agents reduced Bcl-2, while only CAPE and MG132 significantly increased Bax level. CAPE and VCR treatment induced the collapse of mitochondrial membrane potential (∆ψm). All compounds induced cytochrome c release from mitochondrial compartment to cytosol. However, only MG132 caused the translocation of Smac/DIABLO. Except for VCR treatment, all other drugs increased reactive oxygen species (ROS) production level. All treatments induced activation of caspases 3/7, but only CAPE and MG132 led to the activation of caspase 9. In conclusion, our results indicate that CAPE and MG132 treatment of PL104 cells induced apoptosis through the mitochondrial intrinsic pathway, whereas the apoptotic mechanism induced by DOX and VCR may proceed through the extrinsic pathway.

Benzyl isothiocyanate (BITC) induces G2/M phase arrest and apoptosis in human melanoma A375.S2 cells through reactive oxygen species (ROS) and both mitochondria-dependent and death receptor-mediated multiple signaling pathways

Benzyl isothiocyanates (BITC), a member of the isothiocyanate (ITC) family, inhibits cell growth and induces apoptosis in many types of human cancer cell lines. The present study investigated mechanisms underlying BITC-induced apoptosis in A375.S2 human melanoma cancer cells. To observe cell morphological changes and viability, flow cytometric assays, cell counting, and a contrast-phase microscopic examination were carried out in A375.S2 cells after BITC treatment. Cell cycle distribution and apoptosis were assessed with the analysis of cell cycle by flow cytometric assays, DAPI staining, propidium iodide (PI), and annexin V staining. Apoptosis-associated factors such as reactive oxygen species (ROS) formation, loss of mitochondrial membrane potential (ΔΨ(m)), intracellular Ca(2+) release, and caspase-3 activity were evaluated by flow cytometric assays. Abundance of cell cycle and apoptosis associated proteins was determined by Western blotting. AIF and Endo G expression was examined by confocal laser microscope. Results indicated that (1) BITC significantly reduced cell number and induced cell morphological changes in a dose-dependent manner in A375.S2 cells; (2) BITC induced arrest in cell cycle progression at G(2)/M phase through cyclin A, CDK1, CDC25C/Wee1-mediated pathways; (3) BITC induced apoptosis and increased sub-G(1) population; and (4) BITC promoted the production of ROS and Ca(2+) and loss of ΔΨ(m) and caspase-3 activity. Furthermore, BITC induced the down-regulation of Bcl-2 expression and induced up-regulation of Bax in A375.S2 cells. Moreover, BITC-induced cell death was decreased after pretreatment with N-acetyl-l-cysteine (NAC, a ROS scavenger) in A375.S2 cells. In conclusion, the results showed that BITC promoted the induction of G(2)/M phase arrest and apoptosis in A375.S2 human melanoma cells through ER stress- and mitochondria-dependent and death receptor-mediated multiple signaling pathways. These data suggest that BITC has potential as an agent for the treatment of melanoma.

Chamaejasmine induces apoptosis in human lung adenocarcinoma A549 cells through a Ros-mediated mitochondrial pathway

In the present study, the anticancer activity of chamaejasmine towards A549 human lung adenocarcinoma cells was investigated. In order to explore the underlying mechanism of cell growth inhibition of chamaejasmine, cell cycle distribution, ROS generation, mitochondrial membrane potential (Δψ_m) disruption, and expression of cytochrome c, Bax, Bcl-2, caspase-3, caspase-9 and PARP were measured in A549 cells. Chamaejasmine inhibited the growth of A549 cells in a time and dose-dependent manner. The IC₅₀ value was 7.72 µM after 72 h treatment. Chamaejasmine arrested the cell cycle in the G2/M phase and induced apoptosis via a ROS-mediated mitochondria-dependent pathway. Western blot analysis showed that chamaejasmine inhibited Bcl-2 expression and induced Bax expression to desintegrate the outer mitochondrial membrane and causing cytochrome c release. Mitochondrial cytochrome c release was associated with the activation of caspase-9 and caspase-3 cascade, and active-caspase-3 was involved in PARP cleavage. All of these signal transduction pathways are involved in initiating apoptosis. To the best of our knowledge, this is the first report demonstrating the cytotoxic activity of chamaejasmine towards A549 in vitro.

ABC transporters affect the detection of intracellular oxidants by fluorescent probes

Intracellular production of reactive oxygen species (ROS) plays an important role in the control of cell physiology. For the assessment of intracellular ROS production, a plethora of fluorescent probes is commonly used. Interestingly, chemical structures of these probes imply they could be substrates of plasma membrane efflux pumps, called ABC transporters. This study tested whether the determination of intracellular ROS production and mitochondrial membrane potential by selected fluorescent probes is modulated by the expression and activity of ABC transporters. The sub-clones of the HL-60 cell line over-expressing MDR1, MRP1 and BCRP transporters were employed. ROS production measured by luminol- and L-012-enhaced chemiluminescence and cytochrome c reduction assay showed similar levels of ROS production in all the employed cell lines. It was proved that dihydrorhodamine 123, dihexiloxocarbocyanine iodide, hydroethidine, tetrachloro-tetraethylbenzimidazolocarbo-cyanine iodide and tetramethylrhodamine ethyl ester perchlorate are substrates for MDR1; dichlorodihydrofluoresceine, hydroethidine and tetramethylrhodamine ethyl ester perchlorate are substrates for MRP1; dichlorodihydrofluoresceine, dihydrorhodamine 123, hydroethidine and tetrachloro-tetraethylbenzimidazolocarbo-cyanine iodide are substrates for BCRP. Thus, the determination of intracellular ROS and mitochondrial potential by the selected probes is significantly altered by ABC transporter activities. The activity of these transporters must be considered when employing fluorescent probes for the assessment of ROS production or mitochondrial membrane potential.

Mitochondrial dysfunction as a mediator of hippocampal apoptosis in a model of hepatic encephalopathy

In this study, we describe the presence of apoptosis, associated with a mitochondrial dysfunction in the hippocampus of animals in an experimental model defined as minimal hepatic encephalopathy (MHE). This experimental model was studied after 10 days of induced portal vein calibrated stricture, leading to portal hypertension and to a moderate hyperammonemia, without the presence of other evident central nervous system changes. The molecular mechanisms here proposed indicate the presence of apoptotic intrinsic pathways that point to hippocampal mitochondria as an important mediator of apoptosis in this experimental model. In this model of MHE, the presence of DNA fragmentation is documented by 2.3-times increased number of TUNEL-positive cells. These findings together with a higher ratio of the Bcl-2 family members Bax/Bcl-xL in the outer mitochondrial membrane of the MHE animals together with 11% of cytochrome c release indicate the presence of apoptosis in this experimental model. A detailed analysis of the hippocampal mitochondrial physiology was performed after mitochondrial isolation. The determination of the respiratory rate in the presence of malate plus glutamate and ADP showed a 45% decrease in respiratory control in MHE animals as compared with the sham group. A marked decrease of cytochrome oxidase (complex IV of the electron transport chain) was also observed, showing 46% less activity in hippocampal mitochondria from MHE animals. In addition, mitochondria from these animals showed less ability to maintain membrane potential (ΔΨ (m)) which was 13% lower than the sham group. Light scattering experiments showed that mitochondria from MHE animals were more sensitive to swell in the presence of increased calcium concentrations as compared with the sham group. In addition, in vitro studies performed in mitochondria from sham animals showed that mitochondrial permeability transition (MPT) could be a mitochondrial mediator of the apoptotic signaling in the presence of NH(4) (+) and calcium.

Autophagy protects against aminochrome-induced cell death in substantia nigra-derived cell line

Aminochrome, the precursor of neuromelanin, has been proposed to be involved in the neurodegeneration neuromelanin-containing dopaminergic neurons in Parkinson's disease. We aimed to study the mechanism of aminochrome-dependent cell death in a cell line derived from rat substantia nigra. We found that aminochrome (50μM), in the presence of NAD(P)H-quinone oxidoreductase, EC 1.6.99.2 (DT)-diaphorase inhibitor dicoumarol (DIC) (100μM), induces significant cell death (62 ± 3%; p < 0.01), increase in caspase-3 activation (p < 0.001), release of cytochrome C, disruption of mitochondrial membrane potential (p < 0.01), damage of mitochondrial DNA, damage of mitochondria determined with transmission electron microscopy, a dramatic morphological change characterized as cell shrinkage, and significant increase in number of autophagic vacuoles. To determine the role of autophagy on aminochrome-induced cell death, we incubated the cells in the presence of vinblastine and rapamycin. Interestingly, 10μM vinblastine induces a 5.9-fold (p < 0.001) and twofold (p < 0.01) significant increase in cell death when the cells were incubated with 30μM aminochrome in the absence and presence of DIC, respectively, whereas 10μM rapamycin preincubated 24 h before addition of 50μM aminochrome in the absence and the presence of 100μM DIC induces a significant decrease (p < 0.001) in cell death. In conclusion, autophagy seems to be an important protective mechanism against two different aminochrome-induced cell deaths that initially showed apoptotic features. The cell death induced by aminochrome when DT-diaphorase is inhibited requires activation of mitochondrial pathway, whereas the cell death induced by aminochrome alone requires inhibition of autophagy-dependent degrading of damaged organelles and recycling through lysosomes.

MicroRNA-128 downregulates Bax and induces apoptosis in human embryonic kidney cells

MicroRNAs (miRNAs) are short ~21-nt non-coding RNA molecules that have been shown to regulate a number of biological processes. Previous reports have shown that overexpression of miR-128 in glioma cells inhibited cell proliferation. Literature also suggests that miR-128 negatively regulates prostate cancer cell invasion. Here, we show that overexpression of hsa-miR-128, a brain-enriched microRNA, induces apoptosis in HEK293T cells as elucidated by apoptosis assay, cell cycle changes, loss of mitochondrial membrane potential and multicaspase assay. By in silico analysis, we identified a putative target site within the 3' untranslated region (UTR) of Bax, a proapoptotic member of the apoptosis pathway. We found that ectopic expression of hsa-miR-128 suppressed a luciferase reporter containing the Bax-3' UTR and reduced the levels of Bax in HEK293T cells. Taken together, our study demonstrates that overexpression of hsa-miR-128 not only induces apoptosis in HEK293T cells but also is an endogenous regulator of Bax protein.

Shikonin inhibits the proliferation and induces the apoptosis of human HepG2 cells

This study investigated the potential of shikonin as an anticancer agent against liver cancer and an in vitro human hepatoma cancer model system. The HepG2 cell line was the hepatoma cancer model in the present study. The inhibitory effect of shikonin on the growth of HepG2 cells was measured by MTT assay. To explore the underlying mechanism of cell growth inhibition of shikonin, the cell cycle distribution, DNA fragmentation, mitochondrial membrane potential (ΔΨm) disruption, and expression of Bax and Bcl-2 were measured in HepG2 cells. The activity of shikonin in inducing apoptosis was investigated through the detection of Annexin V signal and CD95 expression by flow cytometry and electron microscopy, respectively. Shikonin inhibited the growth of HepG2 cells in a dose-dependent manner. The IC50 value (inhibiting cell growth by 50%) was 4.30 mg/mL. Shikonin inhibited cell growth in a dose-dependent manner and blocked HepG2 cell cycle progression at the S phase. The changes in mitochondrial morphology, dose-dependently decreased in ΔΨm, were observed in different concentrations of the drug treatment group. Western blot analysis showed that cajanol inhibited Bcl-2 expression and induced Bax expression. Furthermore, we show that shikonin increases Annexin V signal and CD95 (Fas/APO) expression, resulting in apoptotic cell death of HepG2 cells. In addition, lump formation of intranuclear chromatin, pyknosis of cell nucleus, deletion of microvillus, vacuolar degeneration of mitochondria, reduction of rough endoplasmic reticulum, and resolution of free ribosome, etc., associated with apoptosis were discovered by electron microscopy in HepG2 cells after 48 h treatment. Shikonin inhibited HepG2 cells, possibly through the pathway of inducing early apoptosis, and was beneficial for restoring the apoptotic sensitivity of HepG2 cells by CD95, and should therefore be considered as a candidate agent for the prevention or treatment of human hepatoma.

Cajanol, a novel anticancer agent from Pigeonpea [Cajanus cajan (L.) Millsp.] roots, induces apoptosis in human breast cancer cells through a ROS-mediated mitochondrial pathway

Cajanol (5-hydroxy-3-(4-hydroxy-2-methoxyphenyl)-7-methoxychroman-4-one) is an isoflavanone from Pigeonpea [Cajanus cajan (L.) Millsp.] roots. As the most effective phytoalexin in pigeonpea, the cytotoxic activity of cajanol towards cancer cells has not been report as yet. In the present study, the anticancer activity of cajanol towards MCF-7 human breast cancer cells was investigated. In order to explore the underlying mechanism of cell growth inhibition of cajanol, cell cycle distribution, DNA fragmentation assay and morphological assessment of nuclear change, ROS generation, mitochondrial membrane potential (DeltaPsim) disruption, and expression of caspase-3 and caspase-9, Bax, Bcl-2, PARP and cytochrome c were measured in MCF-7 cells. Cajanol inhibited the growth of MCF-7 cells in a time and dose-dependent manner. The IC(50) value was 54.05 microM after 72 h treatment, 58.32 microM after 48 h; and 83.42 microM after 24h. Cajanol arrested the cell cycle in the G2/M phase and induced apoptosis via a ROS-mediated mitochondria-dependent pathway. Western blot analysis showed that cajanol inhibited Bcl-2 expression and induced Bax expression to desintegrate the outer mitochondrial membrane and causing cytochrome c release. Mitochondrial cytochrome c release was associated with the activation of caspase-9 and caspase-3 cascade, and active-caspase-3 was involved in PARP cleavage. All of these signal transduction pathways are involved in initiating apoptosis. To the best of our knowledge, this is the first report demonstrating the cytotoxic activity of cajanol towards cancer cells in vitro.

Selective induction of apoptosis in leukemic B-lymphoid cells by a CD19-specific TRAIL fusion protein

Although the treatment outcome of lymphoid malignancies has improved in recent years by the introduction of transplantation and antibody-based therapeutics, relapse remains a major problem. Therefore, new therapeutic options are urgently needed. One promising approach is the selective activation of apoptosis in tumor cells by the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). This study investigated the pro-apoptotic potential of a novel TRAIL fusion protein designated scFvCD19:sTRAIL, consisting of a CD19-specific single-chain Fv antibody fragment (scFv) fused to the soluble extracellular domain of TRAIL (sTRAIL). Potent apoptosis was induced by scFvCD19:sTRAIL in several CD19-positive tumor cell lines, whereas normal blood cells remained unaffected. In mixed culture experiments, selective binding of scFvCD19:sTRAIL to CD19-positive cells resulted in strong induction of apoptosis in CD19-negative bystander tumor cells. Simultaneous treatment of CD19-positive cell lines with scFvCD19:sTRAIL and valproic acid (VPA) or Cyclosporin A induced strongly synergistic apoptosis. Treatment of patient-derived acute B-lymphoblastic leukemia (B-ALL) and chronic B-lymphocytic leukemia (B-CLL) cells resulted in strong tumoricidal activity that was further enhanced by combination with VPA. In addition, scFvCD19:sTRAIL prevented engraftment of human Nalm-6 cells in xenotransplanted NOD/Scid mice. The pre-clinical data presented here warrant further investigation of scFvCD19:sTRAIL as a potential new therapeutic agent for CD19-positive B-lineage malignancies.

Mitochondrial metabolic states regulate nitric oxide and hydrogen peroxide diffusion to the cytosol

Mitochondria isolated from rat heart, liver, kidney and brain (respiratory control 4.0-6.5) release NO and H2O2 at rates that depend on the mitochondrial metabolic state: releases are higher in state 4, about 1.7-2.0 times for NO and 4-16 times for H2O2, than in state 3. NO release in rat liver mitochondria showed an exponential dependence on membrane potential in the range 55 to 180 mV, as determined by Rh-123 fluorescence. A similar behavior was reported for mitochondrial H2O2 production by [S.S. Korshunov, V.P. Skulachev, A.A. Starkov, High protonic potential actuates a mechanism of production of reactive oxygen species in mitochondria. FEBS Lett. 416 (1997) 15_18.]. Transition from state 4 to state 3 of brain cortex mitochondria was associated to a decrease in NO release (50%) and in membrane potential (24-53%), this latter determined by flow cytometry and DiOC6 and JC-1 fluorescence. The fraction of cytosolic NO provided by diffusion from mitochondria was 61% in heart, 47% in liver, 30% in kidney, and 18% in brain. The data supports the speculation that NO and H2O2 report a high mitochondrial energy charge to the cytosol. Regulation of mtNOS activity by membrane potential makes mtNOS a regulable enzyme that in turn regulates mitochondrial O2 uptake and H2O2 production.

Proanthocyanidin from grape seeds enhances doxorubicin-induced antitumor effect and reverses drug resistance in doxorubicin-resistant K562/DOX cells

With the aim of enhancing the efficacy of chemotherapeutic agents, we investigated the antitumor actions and reversal effect on drug resistance of proanthocyanidin plus doxorubicin. The results showed that proanthocyanidin 12.5-200 mg/L significantly inhibited proliferation of K562, K562/DOX, SPC-A-1, and Lewis cells in vitro in a time- and concentration-dependent manner, as determined by microculture tetrazolium assay. A combination of proanthocyani din 12.5, or 25 mg/L and doxorubicin treatment synergistically inhibited cell proliferation with decreased IC50 values. Proanthocyanidin reverses drug resistance in doxorubicin-resistant K562/DOX cells, and IC50 values were decreased by 9.19 (3.64-23.19), 2.56 (1.48-.44), and 0.94 (0.81-1.09) mg/L, respectively, after 24 h treatment with doxorubicin 0.1-9.0 mg/L alone or in combination with proanthocyanidin 12.5 or 25 mg/L; the proanthocyanidin reversal fold was 3.6 and 9.8, respectively. Under confocal laser scanning microscope, the combination of proanthocyanidin 25 or 50 mg/L with doxorubicin 3 mg/L significantly increased the accumulation of intracellular doxorubicin, Ca2+, and Mg2+, and reduced the pH value and mitochondrial membrane potential in K562/DOX cells as compared with doxorubicin alone (p < 0.01). Additionally, the apoptosis rate was increased by 11.3% +/- 3.3%, 14.2% +/- 5.4%, and 23.8% +/- 2.8%, respectively, for doxorubicin 3 mg/L alone or with proanthocyanidin 12.5 or 25 mg/L, as compared with controls (3.0% +/- 1.4%), as demonstrated by flow cytometry. In vivo experiments demonstrated that i.p. administration of proanthocyanidin 10 mg/kg with doxorubicin 2 mg/kg had an inhibitory effect on the growth of transplantation tumor sarcoma 180 and hepatoma 22 in mice as compared with doxorubicin alone (p < 0.05). These results suggest that proanthocyanidin enhances doxorubicin-induced antitumor effect and reverses drug resistance, and its mechanism is attributed partially to the promotion of doxorubicin-induced apoptosis through an elevation of intracellular doxorubicin, and Ca2+, Mg2+ concentration, and a reduction of pH value and mitochondrial membrane potential.