Mitochondria-Judges and Executioners of Cell Death Sentences

Selective inhibition of MCL1 overcomes venetoclax resistance in a murine model of myelodysplastic syndromes

Treatment for myelodysplastic syndromes (MDS) remains insufficient due to clonal heterogeneity and lack of effective clinical therapies. Dysregulation of apoptosis is observed across MDS subtypes regardless of mutations and represents an attractive therapeutic opportunity. Venetoclax (VEN), a selective inhibitor of anti-apoptotic protein B-cell lymphoma- 2 (BCL2), has yielded impressive responses in older patients with acute myeloid leukemia (AML) and high risk MDS. BCL2 family anti-apoptotic proteins BCL-XL and induced myeloid cell leukemia 1 (MCL1) are implicated in leukemia survival, and upregulation of MCL1 is seen in VEN-resistant AML and MDS. We determined in vitro sensitivity of MDS patient samples to selective inhibitors of BCL2, BCL-XL and MCL1. While VEN response positively correlated with MDS with excess blasts, all MDS subtypes responded to MCL1 inhibition. Treatment with combined VEN + MCL1 inhibtion was synergistic in all MDS subtypes without significant injury to normal hematopoiesis and reduced MDS engraftment in MISTRG6 mice, supporting the pursuit of clinical trials with combined BCL2 + MCL1 inhibition in MDS.

Incretin Mimetics Restore the ER-Mitochondrial Axis and Switch Cell Fate Towards Survival in LUHMES Dopaminergic-Like Neurons: Implications for Novel Therapeutic Strategies in Parkinson's Disease

BACKGROUND

Parkinson's disease (PD) is a progressive neurodegenerative movement disorder that afflicts more than 10 million people worldwide. Available therapeutic interventions do not stop disease progression. The etiopathogenesis of PD includes unbalanced calcium dynamics and chronic dysfunction of the axis of the endoplasmic reticulum (ER) and mitochondria that all can gradually favor protein aggregation and dopaminergic degeneration.

OBJECTIVE

In Lund Human Mesencephalic (LUHMES) dopaminergic-like neurons, we tested novel incretin mimetics under conditions of persistent, calcium-dependent ER stress.

METHODS

We assessed the pharmacological effects of Liraglutide-a glucagon-like peptide-1 (GLP-1) analog-and the dual incretin GLP-1/GIP agonist DA3-CH in the unfolded protein response (UPR), cell bioenergetics, mitochondrial biogenesis, macroautophagy, and intracellular signaling for cell fate in terminally differentiated LUHMES cells. Cells were co-stressed with the sarcoplasmic reticulum calcium ATPase (SERCA) inhibitor, thapsigargin.

RESULTS

We report that Liraglutide and DA3-CH analogs rescue the arrested oxidative phosphorylation and glycolysis. They mitigate the suppressed mitochondrial biogenesis and hyper-polarization of the mitochondrial membrane, all to re-establish normalcy of mitochondrial function under conditions of chronic ER stress. These effects correlate with a resolution of the UPR and the deficiency of components for autophagosome formation to ultimately halt the excessive synaptic and neuronal death. Notably, the dual incretin displayed a superior anti-apoptotic effect, when compared to Liraglutide.

CONCLUSIONS

The results confirm the protective effects of incretin signaling in ER and mitochondrial stress for neuronal degeneration management and further explain the incretin-derived effects observed in PD patients.

Mitophagy in ototoxicity

Mitochondrial dysfunction is associated with ototoxicity, which is caused by external factors. Mitophagy plays a key role in maintaining mitochondrial homeostasis and function and is regulated by a series of key mitophagy regulatory proteins and signaling pathways. The results of ototoxicity models indicate the importance of this process in the etiology of ototoxicity. A number of recent investigations of the control of cell fate by mitophagy have enhanced our understanding of the mechanisms by which mitophagy regulates ototoxicity and other hearing-related diseases, providing opportunities for targeting mitochondria to treat ototoxicity.

The Photoperiod Regulates Granulosa Cell Apoptosis through the FSH-Nodal/ALK7 Signaling Pathway in Phodopus sungorus

The photoperiod regulates the seasonal reproduction of mammals by affecting the follicle development, for which the granulosa cells provide nutrition. However, the underlying mechanism remains unclear. Here, Djungarian hamsters (Phodopus sungorus) were raised under different photoperiods to study the ovarian status and explore the potential mechanism of the follicle development mediated by the FSH-Nodal/ALK7 signaling pathway. Compared with the moderate daylight (MD) group, the short daylight (SD) group exhibited a significant decrease in the ovarian weight and increase in the atretic follicle number and granulosa cell apoptosis, whereas the long daylight (LD) group showed an increase in the ovarian weight, the growing follicle number, and the antral follicle number, but a decrease in the granulosa cell apoptosis. Based on these findings, the key genes of the Nodal/ALK7 signaling pathway controlling the granulosa cell apoptosis were studied using the quantitative real-time polymerase chain reaction and western blotting. In the SD group, the follicle-stimulating hormone (FSH) concentration significantly decreased and the Nodal/ALK7/Smad signaling pathways were activated, while the phosphatidylinositol 3-kinase (PIK3)/Akt signaling pathway was inhibited. The BAX expression was significantly increased, while the Bcl-xL expression was significantly decreased, leading to an increase in the caspase-3 activity, the granulosa cell apoptosis, and ovarian degeneration. However, in the LD group, the FSH concentration significantly increased, the Nodal/ALK7/Smad signaling pathway was inhibited, and the PIK3/Akt signaling pathway was activated. Taken together, our results indicate that the photoperiod can regulate the apoptosis of the granulosa cells by regulating the concentration of FSH, activating or inhibiting the Nodal/ALK7 signaling pathway, thereby affecting the ovarian function. Our research provides an important theoretical basis for understanding the photoperiod-regulated mechanisms of the mammalian seasonal reproduction.

Lisaftoclax (APG-2575) Is a Novel BCL-2 Inhibitor with Robust Antitumor Activity in Preclinical Models of Hematologic Malignancy

PURPOSE

Development of B-cell lymphoma 2 (BCL-2)-specific inhibitors poses unique challenges in drug design because of BCL-2 homology domain 3 (BH3) shared homology between BCL-2 family members and the shallow surface of their protein-protein interactions. We report herein discovery and extensive preclinical investigation of lisaftoclax (APG-2575).

EXPERIMENTAL DESIGN

Computational modeling was used to design "lead" compounds. Biochemical binding, mitochondrial BH3 profiling, and cell-based viability or apoptosis assays were used to determine the selectivity and potency of BCL-2 inhibitor lisaftoclax. The antitumor effects of lisaftoclax were also evaluated in several xenograft models.

RESULTS

Lisaftoclax selectively binds BCL-2 (Ki < 0.1 nmol/L), disrupts BCL-2:BIM complexes, and compromises mitochondrial outer membrane potential, culminating in BAX/BAK-dependent, caspase-mediated apoptosis. Lisaftoclax exerted strong antitumor activity in hematologic cancer cell lines and tumor cells from patients with chronic lymphocytic leukemia, multiple myeloma, or Waldenström macroglobulinemia. After lisaftoclax treatment, prodeath proteins BCL-2‒like protein 11 (BIM) and Noxa increased, and BIM translocated from cytosol to mitochondria. Consistent with these apoptotic activities, lisaftoclax entered malignant cells rapidly, reached plateau in 2 hours, and significantly downregulated mitochondrial respiratory function and ATP production. Furthermore, lisaftoclax inhibited tumor growth in xenograft models, correlating with caspase activation, poly (ADP-ribose) polymerase 1 cleavage, and pharmacokinetics of the compound. Lisaftoclax combined with rituximab or bendamustine/rituximab enhanced antitumor activity in vivo.

CONCLUSIONS

These findings demonstrate that lisaftoclax is a novel, orally bioavailable BH3 mimetic BCL-2-selective inhibitor with considerable potential for the treatment of certain hematologic malignancies.

FYCO1 regulates migration, invasion, and invadopodia formation in HeLa cells through CDC42/N-WASP/Arp2/3 signaling pathway

FYCO1, an autophagy adaptor, plays an essential role in the trafficking toward the plus-end of microtubules and the fusion of autophagosomes. Autophagic dysfunction is involved in numerous disease states, including cancers. Previous studies have implicated FYCO1 as one of the critical genes involved in the adenoma to carcinoma transition, but the biological function and mechanism of FYCO1 in carcinogenesis remain unclear. This study aims to elucidate the role and mechanism of up- and downregulation of FYCO1 in mediating tumor effects in HeLa cells. Functionally, FYCO1 promotes cellular migration, invasion, epithelial-mesenchymal transition, invadopodia formation, and matrix degradation, which are detected through wound healing, transwell, immunofluorescence, and Western blot approaches. Interestingly, the data show that although FYCO1 does not affect HeLa cell proliferation, cell cycle distribution, nor vessels' formation, FYCO1 can block the apoptotic function. FYCO1 inhibits cleavage of PARP, caspase3, and caspase9 and increases Bcl-2/Bax ratio. Then, we used CK666, an Arp2/3 specific inhibitor, to confirm that FYCO1 may promote the migration and invasion of HeLa cells through the CDC42/N-WASP/Arp2/3 signaling pathway. Taken together, these results provide a new insight that FYCO1, an autophagy adaptor, may also be a new regulator of tumor metastasis.

Microglial control of neuronal development via somatic purinergic junctions

Microglia, the resident immune cells of the brain, play important roles during development. Although bi-directional communication between microglia and neuronal progenitors or immature neurons has been demonstrated, the main sites of interaction and the underlying mechanisms remain elusive. By using advanced methods, here we provide evidence that microglial processes form specialized contacts with the cell bodies of developing neurons throughout embryonic, early postnatal, and adult neurogenesis. These early developmental contacts are highly reminiscent of somatic purinergic junctions that are instrumental for microglia-neuron communication in the adult brain. The formation and maintenance of these junctions is regulated by functional microglial P2Y12 receptors, and deletion of P2Y12Rs disturbs proliferation of neuronal precursors and leads to aberrant cortical cytoarchitecture during development and in adulthood. We propose that early developmental formation of somatic purinergic junctions represents an important interface for microglia to monitor the status of immature neurons and control neurodevelopment.

Sublethal cytochrome c release generates drug-tolerant persister cells

Drug-tolerant persister cells (persisters) evade apoptosis upon targeted and conventional cancer therapies and represent a major non-genetic barrier to effective cancer treatment. Here, we show that cells that survive treatment with pro-apoptotic BH3 mimetics display a persister phenotype that includes colonization and metastasis in vivo and increased sensitivity toward ferroptosis by GPX4 inhibition. We found that sublethal mitochondrial outer membrane permeabilization (MOMP) and holocytochrome c release are key requirements for the generation of the persister phenotype. The generation of persisters is independent of apoptosome formation and caspase activation, but instead, cytosolic cytochrome c induces the activation of heme-regulated inhibitor (HRI) kinase and engagement of the integrated stress response (ISR) with the consequent synthesis of ATF4, all of which are required for the persister phenotype. Our results reveal that sublethal cytochrome c release couples sublethal MOMP to caspase-independent initiation of an ATF4-dependent, drug-tolerant persister phenotype.

HDAC inhibitor chidamide synergizes with venetoclax to inhibit the growth of diffuse large B-cell lymphoma via down-regulation of MYC, BCL2, and TP53 expression

Diffuse large B-cell lymphoma (DLBCL) is an aggressive type of non-Hodgkin's lymphoma. A total of 10%‒15% of DLBCL cases are associated with myelocytomatosis viral oncogene homolog(MYC) and/or B-cell lymphoma-2 (BCL2) translocation or amplification. BCL2 inhibitors have potent anti-tumor effects in DLBCL; however, resistance can be acquired through up-regulation of alternative anti-apoptotic proteins. The histone deacetylase (HDAC) inhibitor chidamide can induce BIM expression, leading to apoptosis of lymphoma cells with good efficacy in refractory recurrent DLBCL. In this study, the synergistic mechanism of chidamide and venetoclax in DLBCL was determined through in vitro and in vivo models. We found that combination therapy significantly reduced the protein levels of MYC, TP53, and BCL2 in activated apoptotic-related pathways in DLBCL cells by increasing BIM levels and inducing cell apoptosis. Moreover, combination therapy regulated expression of multiple transcriptomes in DLBCL cells, involving apoptosis, cell cycle, phosphorylation, and other biological processes, and significantly inhibited tumor growth in DLBCL-bearing xenograft mice. Taken together, these findings verify the in vivo therapeutic potential of chidamide and venetoclax combination therapy in DLBCL, warranting pre-clinical trials for patients with DLBCL.

Influence of chain length on the anticancer activity of the antimicrobial peptide CAMEL with fatty acid modification

Antimicrobial peptides (AMPs) display promising potential in cancer therapy. Modification with fatty acids is a simple and effective approach to improve the activity of AMPs. In the present study, we investigated the effects of fatty acid chain lengths on the anticancer activity, self-assembly and mechanism of action of CAMEL (CM15, KWKLFKKIGAVLKVL-NH₂), an amphipathic AMP with 15 amino acids. Conjugation of fatty acids could obviously improve the in vitro anticancer activity of CAMEL. Among the tested peptides, C12-CAMEL showed the highest anticancer activity, while C16-CAMEL killed cancer cells with the slowest kinetics. This may be related to the self-assembly of C12-CAMEL and C16-CAMEL, which could form spherical nanoparticles and tightened nanofibers, respectively. In addition, necrosis and necroptosis rather than apoptosis were the major mechanisms underlying the anticancer activity of CAMEL, C12-CAMEL and C16-CAMEL, implying that modification with fatty acids did not obviously alter the mechanism of action of CAMEL. Notably, C12-CAMEL, with high and rapid cell-killing activity, exhibited significantly stronger in vivo anticancer activity than CAMEL and C16-CAMEL. Overall, the present work suggests that the choice of a suitable fatty acid for structural modification is necessary for improving the anticancer activity of AMPs.

Severe cellular stress drives apoptosis through a dual control mechanism independently of p53

For past two decades, p53 has been claimed as the primary sensor initiating apoptosis. Under severe cellular stress, p53 transcriptional activity activates BH3-only proteins such as Bim, Puma, or Noxa to nullify the inhibitory effects of anti-apoptotic proteins on pro-apoptotic proteins for mitochondrial outer membrane permeabilization. Cellular stress determines the expression level of p53, and the amount of p53 corresponds to the magnitude of apoptosis. However, our studies indicated that Bim and Puma are not the target genes of p53 in three cancer models, prostate cancer, glioblastoma, and osteosarcoma. Bim counteracted with Bcl-xl to activate apoptosis independently of p53 in response to doxorubicin-induced severe DNA damage in prostate cancer. Moreover, the transcriptional activity of p53 was more related to cell cycle arrest other than apoptosis for responding to DNA damage stress generated by doxorubicin in prostate cancer and glioblastoma. A proteasome inhibitor that causes protein turnover dysfunction, bortezomib, produced apoptosis in a p53-independent manner in glioblastoma and osteosarcoma. p53 in terms of both protein level and nuclear localization in combining doxorubicin with bortezomib treatment was obviously lower than when using DOX alone, inversely correlated with the magnitude of apoptosis in glioblastoma. Using a BH3-mimetic, ABT-263, to treat doxorubicin-sensitive p53-wild type and doxorubicin-resistant p53-null osteosarcoma cells demonstrated only limited apoptotic response. The combination of doxorubicin or bortezomib with ABT-263 generated a synergistic outcome of apoptosis in both p53-wild type and p53-null osteosarcoma cells. Together, this suggested that p53 might have no role in doxorubicin-induced apoptosis in prostate cancer, glioblastoma and osteosarcoma. The effects of ABT-263 in single and combination treatment of osteosarcoma or prostate cancer indicated a dual control to regulate apoptosis in response to severe cellular stress. Whether our findings only apply in these three types of cancers or extend to other cancer types remains to be explored.

JAK3 mutations and mitochondrial apoptosis resistance in T-cell acute lymphoblastic leukemia

Resistance to mitochondrial apoptosis predicts inferior treatment outcomes in patients with diverse tumor types, including T-cell acute lymphoblastic leukemia (T-ALL). However, the genetic basis for variability in this mitochondrial apoptotic phenotype is poorly understood, preventing its rational therapeutic targeting. Using BH3 profiling and exon sequencing analysis of childhood T-ALL clinical specimens, we found that mitochondrial apoptosis resistance was most strongly associated with activating mutations of JAK3. Mutant JAK3 directly repressed apoptosis in leukemia cells, because its inhibition with mechanistically distinct pharmacologic inhibitors resulted in reversal of mitochondrial apoptotic blockade. Inhibition of JAK3 led to loss of MEK, ERK and BCL2 phosphorylation, and BH3 profiling revealed that JAK3-mutant primary T-ALL patient samples were characterized by a dependence on BCL2. Treatment of JAK3-mutant T-ALL cells with the JAK3 inhibitor tofacitinib in combination with a spectrum of conventional chemotherapeutics revealed synergy with glucocorticoids, in vitro and in vivo. These findings thus provide key insights into the molecular genetics of mitochondrial apoptosis resistance in childhood T-ALL, and a compelling rationale for a clinical trial of JAK3 inhibitors in combination with glucocorticoids for patients with JAK3-mutant T-ALL.

SERTAD1 Sensitizes Breast Cancer Cells to Doxorubicin and Promotes Lysosomal Protein Biosynthesis

Acquired chemoresistance of tumor cells is an unwanted consequence of cancer treatment. Overcoming chemoresistance is particularly important for efficiently improving cancer therapies. Here, using multiple lines of evidence, we report the suppressive role of SERTAD1 in apoptosis/anoikis. Among various breast cancer cell lines, higher SERTAD1 expression was found in MCF7 and MDA-MB-231 in suspension than in adherent cell culture. We revealed an unexpected phenomenon that different types of cell deaths were induced in response to different doses of doxorubicin (Dox) in breast cancer cells, presumably via lysosomal membrane permeabilization. A low dose of Dox highly activated autophagy, while a high dose of the chemotherapy induced apoptosis. Inhibition of SERTAD1 promoted the sensitivity of breast cancer cells to Dox and paclitaxel, leading to a significant reduction in tumor volumes of xenograft mice. Simultaneously targeting cancer cells with Dox and autophagy inhibition successfully induced higher apoptosis/anoikis. The novel role of SERTAD1 in maintaining cellular homeostasis has also been suggested in which lysosomal contents, including LAMP1, LAMP2, CTSB, and CTSD, were reduced in SERTAD1-deficient cells.

Lingbao Huxin Pill Alleviates Apoptosis and Inflammation at Infarct Border Zone through SIRT1-Mediated FOXO1 and NF- κ B Pathways in Rat Model of Acute Myocardial Infarction

OBJECTIVE

To investigate whether Lingbao Huxin Pill (LBHX) protects against acute myocardial infarction (AMI) at the infarct border zone (IBZ) of myocardial tissue by regulating apoptosis and inflammation through the sirtuin 1 (SIRT1)-mediated forkhead box protein O1 (FOXO1) and nuclear factor-κ B (NF-κ B) signaling pathways.

METHODS

Six-week-old Wistar rats with normal diet were randomized into the sham, the model, Betaloc (0.9 mg/kg daily), LBHX-L (0.45 mg/kg daily), LBHX-M (0.9 mg/kg daily), LBHX-H (1.8 mg/kg daily), and LBHX+EX527 (0.9 mg/kg daily) groups according to the method of random number table, 13 in each group. In this study, left anterior descending coronary artery (LADCA) ligation was performed to induce an AMI model in rats. The myocardial infarction area was examined using a 2,3,5-triphenyltetrazolium chloride solution staining assay. A TdT-mediated dUTP nick-end labeling (TUNEL) assay was conducted to assess cardiomyocyte apoptosis in the IBZ. The histopathology of myocardial tissue at the IBZ was assessed with Heidenhain, Masson and hematoxylineosin (HE) staining assays. The expression levels of tumor necrosis factor α (TNF-α), interleukin (IL)-6, IL-1 β, and intercellular adhesion molecule-1 were measured using enzyme-linked immunosorbent assays (ELISAs). The mRNA expressions of SIRT1 and FOXO1 were detected by real-time qPCR (RT-qPCR). The protein expressions of SIRT1, FOXO1, SOD2, BAX and NF- κ B p65 were detected by Western blot analysis.

RESULTS

The ligation of the LADCA successfully induced an AMI model. The LBHX pretreatment reduced the infarct size in the AMI rats (P<0.01). The TUNEL assay revealed that LBHX inhibited cardiomyocyte apoptosis at the IBZ. Further, the histological examination showed that the LBHX pretreatment decreased the ischemic area of myocardial tissue (P<0.05), myocardial interstitial collagen deposition (P<0.05) and inflammation at the IBZ. The ELISA results indicated that LBHX decreased the serum levels of inflammatory cytokines in the AMI rats (P<0.05 or P<0.01). Furthermore, Western blot analysis revealed that the LBHX pretreatment upregulated the protein levels of SIRT1, FOXO1 and SOD2 (P<0.05) and downregulated NF- κ B p65 and BAX expressions (P<0.05). The RT-qPCR results showed that LBHX increased the SIRT1 mRNA and FOXO1 mRNA levels (P<0.05). These protective effects, including inhibiting apoptosis and alleviating inflammation in the IBZ, were partially abolished by EX527, an inhibitor of SIRT1.

CONCLUSION

LBHX could protect against AMI by suppressing apoptosis and inflammation in AMI rats and the SIRT1-mediated FOXO1 and NF- κ B signaling pathways were involved in the cardioprotection effect of LBHX.

CDK4/6 Inhibition Suppresses p73 Phosphorylation and Activates DR5 to Potentiate Chemotherapy and Immune Checkpoint Blockade

Targeting cyclin-dependent kinases 4 and 6 (CDK4/6) is a successful therapeutic approach against breast and other solid tumors. Inhibition of CDK4/6 halts cell cycle progression and promotes antitumor immunity. However, the mechanisms underlying the antitumor activity of CDK4/6 inhibitors are not fully understood. We found that CDK4/6 bind and phosphorylate the p53 family member p73 at threonine 86, which sequesters p73 in the cytoplasm. Inhibition of CDK4/6 led to dephosphorylation and nuclear translocation of p73, which transcriptionally activated death receptor 5 (DR5), a cytokine receptor and key component of the extrinsic apoptotic pathway. p73-mediated induction of DR5 by CDK4/6 inhibitors promoted immunogenic cell death of cancer cells. Deletion of DR5 in cancer cells in vitro and in vivo abrogated the potentiating effects of CDK4/6 inhibitors on immune cytokine TRAIL, 5-fluorouracil chemotherapy, and anti-PD-1 immunotherapy. Together, these results reveal a previously unrecognized consequence of CDK4/6 inhibition, which may be critical for potentiating the killing and immunogenic effects on cancer cells.

SIGNIFICANCE

This work demonstrates how inhibition of CDK4/6 sensitizes cancer cells to chemotherapy and immune checkpoint blockade and may provide a new molecular marker for improving CDK4/6-targeted cancer therapies. See related commentary by Frank, p. 1170.

Pharmacologic Reduction of Mitochondrial Iron Triggers a Noncanonical BAX/BAK-Dependent Cell Death

Cancer cell metabolism is increasingly recognized as providing an exciting therapeutic opportunity. However, a drug that directly couples targeting of a metabolic dependency with the induction of cell death in cancer cells has largely remained elusive. Here we report that the drug-like small-molecule ironomycin reduces the mitochondrial iron load, resulting in the potent disruption of mitochondrial metabolism. Ironomycin promotes the recruitment and activation of BAX/BAK, but the resulting mitochondrial outer membrane permeabilization (MOMP) does not lead to potent activation of the apoptotic caspases, nor is the ensuing cell death prevented by inhibiting the previously established pathways of programmed cell death. Consistent with the fact that ironomycin and BH3 mimetics induce MOMP through independent nonredundant pathways, we find that ironomycin exhibits marked in vitro and in vivo synergy with venetoclax and overcomes venetoclax resistance in primary patient samples.

SIGNIFICANCE

Ironomycin couples targeting of cellular metabolism with cell death by reducing mitochondrial iron, resulting in the alteration of mitochondrial metabolism and the activation of BAX/BAK. Ironomycin induces MOMP through a different mechanism to BH3 mimetics, and consequently combination therapy has marked synergy in cancers such as acute myeloid leukemia. This article is highlighted in the In This Issue feature, p. 587.

Early structural and functional changes in Baikal Sculpin gills exposed to suspended soot microparticles in experiment

The toxic influence of soot microparticles on terrestrial organisms has been well studied, although there is scarce data on how microparticles could affect hydrobionts. We performed a first-ever study of the short-term (5 days) impact of furnace soot (0.005 g/L) on the structural and functional features of gill cells in the Baikal Sculpin species Paracottus knerii, Dybowski, 1874. The soot samples used in the experiment were composed of small (10-100 nm) particles and larger (up to 20 μm) aggregates. The dominant fractions of the polycyclic aromatic hydrocarbons of these microparticles were phenanthrene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzofluoranthenes, benzopyrenes, indeno[1,2,3-c,d]pyrenes, and benzo[ghi]perylene. Trace element analysis of the soot detected the presence of C, S, Si, Al, Ca, K, Mg, P, and Fe. The gill condition was assessed with electron scanning, transmission, and laser confocal microscopy. Soot induces degenerative changes in the macrostructure and surface of secondary lamellae and increases mucus production in fish gills. A decrease in mitochondrial activity, an increase in reactive oxygen species production, and an increase in the frequency of programmed cell death in gill epithelium were observed under the influence of soot. In chloride cells, an induction of macroautophagy was detected. In general, the changes in fish gills after the short-term influence of soot microparticles indicate the stress of respiratory and osmotic regulation systems in fish. The data obtained are important for forming a coherent picture of the impact of soot on hydrobionts and for developing bioindication methods for evaluating the risks of their influence on aquatic ecosystems.

Therapeutic Potential of Perillaldehyde in Ameliorating Vulvovaginal Candidiasis by Reducing Vaginal Oxidative Stress and Apoptosis

Vulvovaginal candidiasis (VVC) is one of the most frequent diseases induced by Candida albicans (C. albicans) during pregnancy, which results in enormous pain to women and their partners in daily life. Perillaldehyde (PAE), a natural monoterpenoid, has significant anti-microbial, anti-inflammatory and anti-oxidation effects. Reactive oxygen species (ROS) are key factors for the host to resist the invasion of fungi. However, excess ROS can cause additional damage independent of the pathogen itself, and the mechanism of ROS in VVC has not been investigated. In this murine study, we revealed that C. albicans infection increased the expression of NADPH oxidase 2 (NOX2) and the content of malonaldehyde (MDA). C. albicans inhibited the activity of antioxidant enzymes in the vagina, including superoxide dismutase (SOD), Catalase (CAT), glutathione peroxidase (GSH-PX) and heme oxygenase (HO-1), which were returned to normal levels after treatment with PAE. Furthermore, PAE inhibited the activities of Keap1 and promoted Nrf2 transfer from cytoplasm to nucleus, which were mediated by excessive accumulation of ROS in the VVC mice. In this study, we also indicated that PAE inhibited the apoptosis of vagina cells via Caspase 9- Caspase 7-PARP pathway and prevented the release of IL-1ꞵ in VVC mice. In summary, this study revealed that the treatment of VVC in mice with PAE might be mediated by inhibition of ROS, and established the therapeutic potential of PAE as an antifungal agent for the treatment of VVC.

Toxoplasma gondii Induces Apoptosis via Endoplasmic Reticulum Stress-Derived Mitochondrial Pathway in Human Small Intestinal Epithelial Cell-Line

Toxoplasma gondii, an intracellular protozoan parasite that infects one-third of the world’s population, has been reported to hijack host cell apoptotic machinery and promote either an anti- or proapoptotic program depending on the parasite virulence and load and the host cell type. However, little is known about the regulation of human FHs 74 small intestinal epithelial cell viability in response to T. gondii infection. Here we show that T. gondii RH strain tachyzoite infection or ESP treatment of FHs 74 Int cells induced apoptosis, mitochondrial dysfunction and ER stress in host cells. Pretreatment with 4-PBA inhibited the expression or activation of key molecules involved in ER stress. In addition, both T. gondii and ESP challenge-induced mitochondrial dysfunction and cell death were dramatically suppressed in 4-PBA pretreated cells. Our study indicates that T. gondii infection induced ER stress in FHs 74 Int cells, which induced mitochondrial dysfunction followed by apoptosis. This may constitute a potential molecular mechanism responsible for the foodborne parasitic disease caused by T. gondii.

Simvastatin potentiates the cell-killing activity of imatinib in imatinib-resistant chronic myeloid leukemia cells mainly through PI3K/AKT pathway attenuation and Myc downregulation

Constitutively activated BCR-ABL kinase is considered the driver event responsible in the initiation and development of chronic myeloid leukemia (CML). The advent of the first BCR-ABL inhibitor imatinib has significantly improved the clinical outcome of CML cases. However, resistance to imatinib occurs in 25-30% of CML patients. Due to the lack of effective therapeutic strategies, novel treatment approaches are urgently required for imatinib-resistant CML. Simvastatin, a well-known HMG-CoA reductase inhibitor that confers tremendous clinical benefits in cardiovascular diseases, has attracted mounting attentions for its potent antitumor effects on multiple tumor types. In this study, we demonstrated that simvastatin monotherapy was effective in diminishing cell viability in both imatinib-sensitive and imatinib-resistant CML cells, including T351I mutated cells, with the latter being less vulnerable to the simvastatin than the former. Notably, we found that simvastatin acted as a robust cytotoxic sensitizer of imatinib to kill imatinib-resistant and T315I mutated CML cells in vitro and in vivo. Mechanistically, the cooperative interaction of simvastatin and imatinib was associated with the inactivation of the PI3K/Akt signaling pathway, which was a classical downstream pro-survival cascade of the BCR-ABL kinase. In addition, this drug combination obviously decreased Myc expression through attenuation of canonical Wnt/β-catenin signaling and increased H3K27 trimethylation. Taken together, we provide attractive preclinical results for the combinatorial regimen of simvastatin and imatinib against imatinib-resistant and T315I mutated CML cells. This combined regimens warrants further clinical investigations in patients with imatinib-resistant CML.

Quercetin Reduces Oxidative Stress and Apoptosis by Inhibiting HMGB1 and Its Translocation, Thereby Alleviating Liver Injury in ACLF Rats

Background

Acute on chronic liver failure (ACLF) is a syndrome of acute liver failure that occurs on the basis of chronic liver disease, which is characterized by a rapid deterioration in a short period and high mortality. High mobility group box 1 (HMGB1) may be involved in the pathological process of ACLF; its specific role remains to be further elucidated. Our previous studies have shown that quercetin (Que) exerts anti-oxidant and anti-apoptotic effects by inhibiting HMGB1 in vitro. The present study aimed to investigate the effect of Que on liver injury in ACLF rats.

Methods

The contents of ALT, AST, TBiL, and PT time of rats in each group were observed. HE staining was used to detect liver pathology. The levels of oxidative stress indicators such as MDA, GSH, and 4-HNE in the rat liver were detected. TUNEL assay was used to detect apoptosis in rat hepatocytes. Immunofluorescence and western blot analysis were performed to explore the protective effect of Que on ACLF rats and the underlying mechanism.

Results

The results showed that Que could reduce the increase of serum biochemical indices, improve liver pathology, and reduce liver damage in ACLF rats. Further results confirmed that Que reduced the occurrence of oxidative stress and apoptosis of hepatocytes, and these reactions may aggravate the progress of ACLF. Meanwhile, the results of immunofluorescence and western blotting also confirmed that the expression of HMGB1 and extranuclear translocation in ACLF rat hepatocytes were significantly increased, which was alleviated by the treatment of Que. In addition, when cotreated with glycyrrhizin (Gly), an inhibitor of HMGB1, the inhibition of Que on HMGB1 and its translocation, apoptosis and oxidative stress, and the related proteins of HMGB1-mediated cellular pathway have been significantly enhanced.

Conclusion

Thus, Que alleviates liver injury in ACLF rats, and its mechanism may be related to oxidative stress and apoptosis caused by HMGB1 and its translocation.

Trichomonas vaginalis induces apoptosis via ROS and ER stress response through ER-mitochondria crosstalk in SiHa cells

Background

Trichomonas vaginalis causes lesions on the cervicovaginal mucosa in women; however, its pathogenesis remains unclear. We have investigated the involvement of the endoplasmic reticulum (ER) in the induction of apoptosis by T. vaginalis and its molecular mechanisms in human cervical cancer SiHa cells.

Methods

Apoptosis, reactive oxygen species (ROS) production, mitochondrial membrane potential (MMP), ER stress response and Bcl-2 family protein expression were evaluated using immunocytochemistry, flow cytometry, 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethyl-imidacarbocyanine iodide dye staining and western blotting.

Results

Trichomonas vaginalis induced mitochondrial ROS production, apoptosis, the ER stress response and mitochondrial dysfunction, such as MMP depolarization and an imbalance in Bcl-2 family proteins, in SiHa cells in a parasite burden- and infection time-dependent manner. Pretreatment with N-acetyl cysteine (ROS scavenger) or 4-phenylbutyric acid (4-PBA; ER stress inhibitor) significantly alleviated apoptosis, mitochondrial ROS production, mitochondrial dysfunction and ER stress response in a dose-dependent manner. In addition, T. vaginalis induced the phosphorylation of apoptosis signal regulating kinase 1 (ASK1) and c-Jun N-terminal kinases (JNK) in SiHa cells, whereas 4-PBA or SP600125 (JNK inhibitor) pretreatment significantly attenuated ASK1/JNK phosphorylation, mitochondrial dysfunction, apoptosis and ER stress response in SiHa cells, in a dose-dependent manner. Furthermore, T. vaginalis excretory/secretory products also induced mitochondrial ROS production, apoptosis and the ER stress response in SiHa cells, in a time-dependent manner.

Conclusions

Trichomonas vaginalis induces apoptosis through mitochondrial ROS and ER stress responses, and also promotes ER stress-mediated mitochondrial apoptosis via the IRE1/ASK1/JNK/Bcl-2 family protein pathways in SiHa cells. These data suggest that T. vaginalis-induced apoptosis is affected by ROS and ER stress response via ER–mitochondria crosstalk.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-05098-2.

Synthesis, biological evaluation and cellular localization study of fluorescent derivatives of Jiyuan Oridonin A

Jiyuan Oridonin A (JOA) is a naturally occurring ent-kaurane diterpenoid that exhibits significant potential in the field of anti-tumor drug development. However, its detailed anti-cancer mechanism of action has not been fully understood. In order to investigate its anticancer mode of action, two series of novel fluorescent derivatives of JOA conjugated with naphthalimide dyes were synthesized, and their antitumor activity against five selected cancer cell lines (MGC-803, SW1990, PC-3, TE-1 and HGC-27) was evaluated. Compared with JOA, the anti-tumor activity of the vast majority of compounds were improved. Among them, B12 exhibited promising anti-proliferative activity against HGC-27 cells with IC₅₀ value of 0.39 ± 0.09 μM. Fluorescence imaging studies demonstrated that probe B12 could enter HGC-27 cells in a dose-dependent and time-dependent manner and was mainly accumulated in mitochondria. Preliminary biological mechanism studies indicated that B12 was able to inhibit cell cloning and migration. Further studies suggested that B12-induced apoptosis was related to the mitochondrial pathway. Overall, our results provide new approaches to explore the molecular mechanism of the natural product JOA, which would contribute to its further development as an antitumor agent.

Recent progress of organic small molecule-based fluorescent probes for intracellular pH sensing

Fluorescent probes along with fluorescence microscopy are essential tools for biomedical research. Various cellular ubiquitous chemical factors such as pH, H₂O₂, and Ca²⁺ are labeled and traced using specific fluorescent probes, therefore helping us to explore their physiological function and pathological change. Among them, intracellular pH value is an important factor that governs biological processes, generally ∼7.2. Furthermore, specific organelles within cells possess unique acid-base homeostasis, involving the acidic lysosomes, alkalescent mitochondria, and neutral endoplasmic reticulum and Golgi apparatus, which undergo various physiological processes such as intracellular digestion, ATP production, and protein folding and processing. In this review, recently reported fluorescent probes targeted toward the lysosomes, mitochondria, endoplasmic reticulum, Golgi apparatus, and cytoplasm for sensing pH change are discussed, which involves molecular structures, fluorescence behavior, and biological applications.

Endoplasmic Reticulum-Mitochondria Contacts: A Potential Therapy Target for Cardiovascular Remodeling-Associated Diseases

Cardiovascular remodeling occurs in cardiomyocytes, collagen meshes, and vascular beds in the progress of cardiac insufficiency caused by a variety of cardiac diseases such as chronic ischemic heart disease, chronic overload heart disease, myocarditis, and myocardial infarction. The morphological changes that occur as a result of remodeling are the critical pathological basis for the occurrence and development of serious diseases and also determine morbidity and mortality. Therefore, the inhibition of remodeling is an important approach to prevent and treat heart failure and other related diseases. The endoplasmic reticulum (ER) and mitochondria are tightly linked by ER-mitochondria contacts (ERMCs). ERMCs play a vital role in different signaling pathways and provide a satisfactory structural platform for the ER and mitochondria to interact and maintain the normal function of cells, mainly by involving various cellular life processes such as lipid metabolism, calcium homeostasis, mitochondrial function, ER stress, and autophagy. Studies have shown that abnormal ERMCs may promote the occurrence and development of remodeling and participate in the formation of a variety of cardiovascular remodeling-associated diseases. This review focuses on the structure and function of the ERMCs, and the potential mechanism of ERMCs involved in cardiovascular remodeling, indicating that ERMCs may be a potential target for new therapeutic strategies against cardiovascular remodeling-induced diseases.

BET protein degradation triggers DR5-mediated immunogenic cell death to suppress colorectal cancer and potentiate immune checkpoint blockade

Bromodomain and extra-terminal domain (BET) family proteins are epigenetic readers that play a critical role in oncogenesis by controlling the expression of oncogenes such as c-Myc. Targeting BET family proteins has recently emerged as a promising anticancer strategy. However, the molecular mechanisms by which cancer cells respond to BET inhibition are not well understood. In this study, we found that inducing the degradation of BET proteins by the proteolysis targeting chimeras (PROTAC) approach potently suppressed the growth of colorectal cancer (CRC) including patient-derived tumors. Mechanistically, BET degradation transcriptionally activates Death Receptor 5 (DR5) to trigger immunogenic cell death (ICD) in CRC cells. Enhanced DR5 induction further sensitizes CRC cells with a mutation in Speckle-type POZ protein (SPOP). Furthermore, DR5 is indispensable for a striking antitumor effect of combining BET degradation and anti-PD-1 antibody, which was well tolerated in mice and almost eradicated syngeneic tumors. Our results demonstrate that BET degradation triggers DR5-mediated ICD to potently suppress CRC and potentiate immune checkpoint blockade. These results provide a rationale, mechanistic insights, and potential biomarkers for developing a precision CRC therapy by inducing BET protein degradation.

The endocytic pathway of Pt nanoclusters and their induced apoptosis of A549 and A549/Cis cells through c-Myc/p53 and Bcl-2/caspase-3 signaling pathways

In recent years, multifunctional platinum nanoclusters (Pt-NCs) as new Pt-based anti-cancer drugs exhibit a promising therapeutic efficiency for several cancer diseases, especially for human pulmonary carcinoma. However, the endocytosis behaviors (like uptake pathway, etc.) and induced apoptosis mechanism of Pt-NCs for drug-resistant non-small cell lung cancer (NSCLC), are still inconclusive. In this research, we explored the endocytic pathway of Pt-NCs in both typical NSCLC A549 cells and cisplatin-resistant A549/Cis cells through qualitative confocal laser scanning microscope (CLSM) measurement and quantitative flow cytometry (FCM) and inductive coupled plasma-optical emission spectroscopy (ICP-OES) analysis, by the means of introducing the specific inhibitors which impede the classical ways of endocytosis. It was found that Pt-NCs dominatingly entered A549 cells via caveolin-mediated endocytosis as well as A549/Cis cells through micropinocytosis approach. Pt-NCs possessed an excellent inhibitory effect on the cell proliferation, migration and invasion, which the cell activity of A549 cells reduced to 14% and that of A549/Cis cells went down about four fifths. Moreover, Pt-NCs treatment increased caspase-3 protein levels and downregulated the expression of c-Myc and Bcl-2, proving the Pt-NCs-induced apoptosis of NSCLC cells was related to c-Myc/p53 and Bcl-2/caspase-3 signal pathways. These results demonstrate the explicit uptake pathway and apoptotic signaling pathway of Pt-NCs for NSCLC, which provides an in-depth and reasonable theoretical basis for the development of new Pt-NCs-based chemotherapeutics in future clinical practice.

The multifaceted roles of mitochondria at the crossroads of cell life and death in cancer

Mitochondria are the cytoplasmic organelles mostly known as the "electric engine" of the cells; however, they also play pivotal roles in different biological processes, such as cell growth/apoptosis, Ca²⁺ and redox homeostasis, and cell stemness. In cancer cells, mitochondria undergo peculiar functional and structural dynamics involved in the survival/death fate of the cell. Cancer cells use glycolysis to support macromolecular biosynthesis and energy production ("Warburg effect"); however, mitochondrial OXPHOS has been shown to be still active during carcinogenesis and even exacerbated in drug-resistant and stem cancer cells. This metabolic rewiring is associated with mutations in genes encoding mitochondrial metabolic enzymes ("oncometabolites"), alterations of ROS production and redox biology, and a fine-tuned balance between anti-/proapoptotic proteins. In cancer cells, mitochondria also experience dynamic alterations from the structural point of view undergoing coordinated cycles of biogenesis, fusion/fission and mitophagy, and physically communicating with the endoplasmic reticulum (ER), through the Ca²⁺ flux, at the MAM (mitochondria-associated membranes) levels. This review addresses the peculiar mitochondrial metabolic and structural dynamics occurring in cancer cells and their role in coordinating the balance between cell survival and death. The role of mitochondrial dynamics as effective biomarkers of tumor progression and promising targets for anticancer strategies is also discussed.

Emerging role of BAD and DAD1 as potential targets and biomarkers in cancer

As key regulators of apoptosis, BAD and defender against apoptotic cell death 1 (DAD1) are associated with cancer initiation and progression. Multiple studies have demonstrated that BAD and DAD1 serve critical roles in several types of cancer and perform various functions, such as participating in cellular apoptosis, invasion and chemosensitivity, as well as their role in diagnostic/prognostic judgement, etc. Investigating the detailed mechanisms of the cancerous effects of the two proteins will contribute to enriching the options for targeted therapy, and may improve clinical treatment of cancer. The present review summarizes research advances regarding the associations of BAD and DAD1 with cancer, and a hypothesis on the feasible relationship and interaction mechanism between the two proteins is proposed. Furthermore, the present review highlights the potential of the two proteins as therapeutic targets and valuable diagnostic and prognostic biomarkers.

Aromatic hydrocarbon receptors in mitochondrial biogenesis and function

Mitochondria are ubiquitous membrane-bound organelles that not only play a key role in maintaining cellular energy homeostasis and metabolism but also in signaling and apoptosis. Aryl hydrocarbons receptors (AhRs) are ligand-activated transcription factors that recognize a wide variety of xenobiotics, including polyaromatic hydrocarbons and dioxins, and activate diverse detoxification pathways. These receptors are also activated by natural dietary compounds and endogenous metabolites. In addition, AhRs can modulate the expression of a diverse array of genes related to mitochondrial biogenesis and function. The aim of the present review is to analyze scientific data available on the AhR signaling pathway and its interaction with the intracellular signaling pathways involved in mitochondrial functions, especially those related to cell cycle progression and apoptosis. Various evidence have reported the crosstalk between the AhR signaling pathway and the nuclear factor κB (NF-κB), tyrosine kinase receptor signaling and mitogen-activated protein kinases (MAPKs). The AhR signaling pathway seems to promote cell cycle progression in the absence of exogenous ligands, whereas the presence of exogenous ligands induces cell cycle arrest. However, its effects on apoptosis are controversial since activation or overexpression of AhR has been observed to induce or inhibit apoptosis depending on the cell type. Regarding the mitochondria, although activation by endogenous ligands is related to mitochondrial dysfunction, the effects of endogenous ligands are not well understood but point towards antiapoptotic effects and inducers of mitochondrial biogenesis.

Lanatoside C inhibits human cervical cancer cell proliferation and induces cell apoptosis by a reduction of the JAK2/STAT6/SOCS2 signaling pathway

Cervical cancer is one of the leading causes of cancer-associated mortality in gynecological diseases and ranks third among female cancers worldwide. Although early detection and vaccination have reduced incidence rates, cancer recurrence and metastasis lead to high mortality due to the lack of effective medicines. The present study aimed to identify novel drug candidates to treat cervical cancer. In the present study, lanatoside C, an FDA-approved cardiac glycoside used for the treatment of heart failure, was demonstrated to have anti-proliferative and cytotoxic effects on cervical cancer cells, with abrogation of cell migration in a dose-dependent manner. Lanatoside C also triggered cell apoptosis by enhancing reactive oxygen species production and reducing the mitochondrial membrane potential, which induced cell cycle arrest at the S and G₂/M phases. Furthermore, lanatoside C inhibited the phosphorylation of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 6 (STAT6), while inducing the expression of suppressor of cytokine signaling 2, a negative regulator of JAK2-STAT6 signaling. Taken together, the results of the present study suggest that lanatoside C suppresses cell proliferation and induces cell apoptosis by inhibiting JAK2-STAT6 signaling, indicating that lanatoside C is a promising agent for the treatment of cervical cancer.

Dual Inhibition of Histone Deacetylases and the Mechanistic Target of Rapamycin Promotes Apoptosis in Cell Line Models of Uveal Melanoma

Purpose

Over 90% of uveal melanomas harbor pathogenic variants of the GNAQ or GNA11 genes that activate survival pathways. As previous studies found that Ras-mutated cell lines were vulnerable to a combination of survival pathway inhibitors and the histone-deacetylase inhibitor romidepsin, we investigated whether this combination would be effective in models of uveal melanoma.

Methods

A small-scale screen of inhibitors of bromodomain-containing protein 4 (BRD4; OTX-015), extracellular signal-related kinase (ERK; ulixertinib), mechanistic target of rapamycin (mTOR; AZD-8055), or phosphoinositide 3-kinase (PI3K; GDC-0941) combined with a clinically relevant administration of romidepsin was performed on a panel of uveal melanoma cell lines (92.1, Mel202, MP38, and MP41) and apoptosis was quantified by flow cytometry after 48 hours. RNA sequencing analysis was performed on Mel202 cells treated with romidepsin alone, AZD-8055 alone, or the combination, and protein changes were validated by immunoblot.

Results

AZD-8055 with romidepsin was the most effective combination in inducing apoptosis in the cell lines. Increased caspase-3 and PARP cleavage were noted in the cell lines when they were treated with romidepsin and mTOR inhibitors. RNA sequencing analysis of Mel202 cells revealed that apoptosis was the most affected pathway in the romidepsin/AZD-8055-treated cells. Increases in pro-apoptotic BCL2L11 and decreases in anti-apoptotic BIRC5 and BCL2L1 transcripts noted in the sequencing analysis were confirmed at the protein level in Mel202 cells.

Conclusions

Our data suggest that romidepsin in combination with mTOR inhibition could be an effective treatment strategy against uveal melanoma due in part to changes in apoptotic proteins.

[Dibenzyl trisulfide inhibits proliferation and induces apoptosis of HN30 cells via Akt/ p53 signaling pathway]

OBJECTIVE

To explore the effect of dibenzyl trisulfide (DTS) on cell proliferation and apoptosis in human head and neck squamous cell carcinoma (HNSCC) HN30 cells.

OBJECTIVE

The effects of DTS on proliferation of HNSCC cell lines HN30, HN12, and SCC25 were examined by assessing colony formation ability of the treated cells. The effect of different concentrations of DTS on viability of HN30 cells was assessed using MTT assay. HN30 cells were treated with 3, 10, or 30 μmol/L DTS for 24 h, and the cell apoptosis and mitochondrial membrane potential (MMP) were detected using flow cytometry with annexin Ⅴ-FITC/PI double staining and JC-1 fluorescent probe staining. Western blotting was performed to determine the protein expressions of caspase-3, cleaved caspase-3 and Bcl-2 in the treated cells. The phosphorylation levels of Akt and p53 in HN30 cells were detected using Western blotting after treatment with 10 μmol/L DTS for 0.5, 1, 2, 4, 8, or 16 h.

OBJECTIVE

DTS at 1 μmol/L significantly inhibited the proliferation of HN30, HN12 and SCC25 cells as shown by colony formation assay. MTT assay showed that DTS dose-dependently decreased HN30 cell viability as compared with the solvent control group, and 100 μmol/L DTS produced the strongest inhibitory effect (P < 0.0001). Treatment with DTS below 30 μmol/L concentrationdependently promoted apoptosis (P < 0.01) and lowered the MMP (P < 0.01) of HN30 cells, and after treatment for 24 h, the cells showed significantly increased cleaved caspase-3 (P < 0.01) and decreased Bcl-2 expression (P < 0.01). Treatment with 10 μmol/L DTS for 16 h significantly inhibited Akt phosphorylation (P < 0.001) and enhanced p53 phosphorylation (P < 0.01) in HN30 cells.

OBJECTIVE

DTS inhibits proliferation and induces apoptosis of HN30 cells possibly through mechanisms involving the inhibition of Akt and the activation of p53.

Metabolic perturbations sensitize triple-negative breast cancers to apoptosis induced by BH3 mimetics

Cancer cells have differential metabolic dependencies compared to their nonmalignant counterparts. However, few metabolism-targeting compounds have been successful in clinical trials. Here, we investigated the metabolic vulnerabilities of triple-negative breast cancer (TNBC), particularly those metabolic perturbations that increased mitochondrial apoptotic priming and sensitivity to BH3 mimetics (drugs that antagonize antiapoptotic proteins). We used high-throughput dynamic BH3 profiling (HT-DBP) to screen a library of metabolism-perturbing small molecules, which revealed inhibitors of the enzyme nicotinamide phosphoribosyltransferase (NAMPT) as top candidates. In some TNBC cells but not in nonmalignant cells, NAMPT inhibitors increased overall apoptotic priming and induced dependencies on specific antiapoptotic BCL-2 family members. Treatment of TNBC cells with NAMPT inhibitors sensitized them to subsequent treatment with BH3 mimetics. The combination of a NAMPT inhibitor (FK866) and an MCL-1 antagonist (S63845) reduced tumor growth in a TNBC patient-derived xenograft model in vivo. We found that NAMPT inhibition reduced NAD⁺ concentrations below a critical threshold that resulted in depletion of adenine, which was the metabolic trigger that primed TNBC cells for apoptosis. These findings demonstrate a close interaction between metabolic and mitochondrial apoptotic signaling pathways and reveal that exploitation of a tumor-specific metabolic vulnerability can sensitize some TNBC to BH3 mimetics.

Venetoclax in combination with azacitidine in Japanese patients with acute myeloid leukaemia: phase 1 trial findings

BACKGROUND

Venetoclax plus azacitidine is indicated in the USA for the treatment of newly diagnosed acute myeloid leukaemia in older patients (≥75 years) or those ineligible for induction chemotherapy due to co-morbidities.

METHODS

In this phase 1/2 study (NCT02265731), Japanese patients (≥60 years) with untreated (ineligible for induction chemotherapy) or relapsed/refractory acute myeloid leukaemia received oral venetoclax 400 mg/day (3-day ramp up in cycle 1) plus subcutaneous or intravenous azacitidine 75 mg/m2 on days 1-7 per 28-day cycle until disease progression or unacceptable toxicity.

RESULTS

As of 10 December 2019, six patients were enrolled (median age: 75 years; untreated: n = 5; relapsed/refractory: n = 1); median treatment duration: 10.3 months (range, 0.7-29.4). Most common grade ≥ 3 adverse events were lymphopaenia and febrile neutropaenia (n = 4 each). Four patients reported serious adverse events; only an event of grade 3 fungal pneumonia was considered possibly related to both study drugs, requiring dose interruption of venetoclax and delay of azacitidine. Five (83%) patients had responses (complete remission: n = 3). Median time to first response of complete remission/complete remission with incomplete count recovery was 1.0 month (range, 0.8-5.5); median overall survival: 15.7 months (95% confidence interval: 6.2, not reached).

CONCLUSIONS

Venetoclax plus azacitidine was well tolerated and showed high response rates in Japanese patients with acute myeloid leukaemia.

Ferroptosis in Different Pathological Contexts Seen through the Eyes of Mitochondria

Ferroptosis is a recently described form of regulated cell death characterized by intracellular iron accumulation and severe lipid peroxidation due to an impaired cysteine-glutathione-glutathione peroxidase 4 antioxidant defence axis. One of the hallmarks of ferroptosis is a specific morphological phenotype characterized by extensive ultrastructural changes of mitochondria. Increasing evidence suggests that mitochondria play a significant role in the induction and execution of ferroptosis. The present review summarizes existing knowledge about the mitochondrial impact on ferroptosis in different pathological states, primarily cancer, cardiovascular diseases, and neurodegenerative diseases. Additionally, we highlight pathologies in which the ferroptosis/mitochondria relation remains to be investigated, where the process of ferroptosis has been confirmed (such as liver- and kidney-related pathologies) and those in which ferroptosis has not been studied yet, such as diabetes. We will bring attention to avenues that could be followed in future research, based on the use of mitochondria-targeted approaches as anti- and proferroptotic strategies and directed to the improvement of existing and the development of novel therapeutic strategies.

Protective effects of fucoidan against ethanol-induced liver injury through maintaining mitochondrial function and mitophagy balance in rats

For alcoholic liver disease (ALD), mitophagy has been reported as a promising therapeutic strategy to alleviate the hepatic lesion elicited by ethanol. This study was conducted to investigate the regulatory effects of fucoidan on mitophagy induced by chronic ethanol administration in rats. Here, 20 male rats in each group were treated with fucoidan (150 and 300 mg per kg body weight) by gavage once daily. Up to 56% liquor (7 to 9 mL per kg body weight) was orally administered 1 h after the fucoidan treatment for 20 weeks. The results showed that chronic ethanol consumption elevated the levels of hepatic enzymes (ALT, AST, and GGT) and triglyceride (TG) contents, with liver antioxidant enzymes being decreased and lipid peroxidation products increased and thus initiating the mitochondria-induced endogenous apoptotic pathway. Furthermore, ethanol-induced excessive oxidative stress inhibited the function of mitochondria and promoted damaged mitochondria accumulation which stimulated the PTEN-induced putative kinase 1 (PINK1) and Parkin associated mitophagic pathway in the liver. In contrast, the fucoidan pretreatment alleviated ethanol-induced histopathological changes, disorders of lipid metabolism, and oxidative damage with mitophagy related proteins and mitochondrial dynamics-related proteins namely mitochondrial E3 ubiquitin ligase 1 (Mul1), mitofusin2 (Mfn2) and dynamin-related protein 1 (Drp1) being restored to a normal level. In summary, our findings suggest that fucoidan pretreatment protects against ethanol-induced damaged mitochondria accumulation and over-activated mitophagy, which plays a pivotal role in maintaining mitochondrial homeostasis and ensuring mitochondrial quality.

Venetoclax-based combinations for the treatment of newly diagnosed acute myeloid leukemia

Elderly and/or unfit patients with acute myeloid leukemia have historically been challenging to manage as they were ineligible for what was considered standard of care treatment with induction chemotherapy. The emergence of venetoclax with hypomethylating agents or low-dose cytarabine has substantially improved outcomes in the frontline setting with manageable toxicity. However, this regimen can be challenging to deliver given its differences from standard intensive chemotherapy. In this review, we summarize the landmark trials that established venetoclax-based combinations as a new standard of care for patients with acute myeloid leukemia not suitable for intense chemotherapy, provide practical clinical pearls for managing patients on these therapies, and offer a brief overview of modifications to these regimens under development to improve their efficacy and/or applicability.

Silver nanoparticles induce apoptosis via NOX4-derived mitochondrial reactive oxygen species and endoplasmic reticulum stress in colorectal cancer cells

Aim: To investigate the anticancer mechanisms of silver nanoparticles (AgNPs) in colorectal cancer. Methods: Anticancer effects of AgNPs were determined in colorectal cancer HCT116 cells and xenograft mice using cellular and molecular methods. Results: AgNPs induced mitochondrial reactive oxygen species production, mitochondrial dysfunction and endoplasmic reticulum (ER) stress responses through NOX4 and led to HCT116 cell apoptosis. Pretreatment with DPI or 4-PBA significantly inhibited mitochondrial reactive oxygen species production, apoptosis, ER stress response, NOX4 expression and mitochondrial dysfunction in AgNP-treated HCT116 cells. AgNPs also significantly suppressed HCT116 cell-based xenograft tumor growth in nude mice by inducing apoptosis and ER stress responses. Conclusion: AgNPs exert anticancer effects against colorectal cancer via ROS- and ER stress-related mitochondrial apoptosis pathways.

Failed Apoptosis Enhances Melanoma Cancer Cell Aggressiveness

Triggering apoptosis remains an efficient strategy to treat cancer. However, apoptosis is no longer a final destination since cancer cells can undergo partial apoptosis without dying. Recent evidence shows that partial mitochondrial permeabilization and non-lethal caspase activation occur under certain circumstances, although it remains unclear how failed apoptosis affects cancer cells. Using a cancer cell model to trigger non-lethal caspase activation, we find that melanoma cancer cells undergoing failed apoptosis have a particular transcriptomic signature associated with focal adhesions, transendothelial migration, and modifications of the actin cytoskeleton. In line with this, cancer cells surviving apoptosis gain migration and invasion properties in vitro and in vivo. We further demonstrate that failed apoptosis-associated gain in invasiveness is regulated by the c-Jun N-terminal kinase (JNK) pathway, whereas its RNA sequencing signature is found in metastatic melanoma. These findings advance our understanding of how cell death can both cure and promote cancer.

Dietary flavone from the Tetrastigma hemsleyanum vine triggers human lung adenocarcinoma apoptosis via autophagy

Among all types of cancers, lung cancer ranks first in morbidity and mortality, and non-small cell lung cancer (NSCLC) accounts for 80-85% of all lung cancer cases. Chemotherapy has shown promising results, but the accompanying side-effects cannot be neglected. Herein, we introduce novel flavones (TVF), which were characterized as 3-caffeoylquinic acid, 5-caffeoylquinic acid, quercetin-3-O-rutinoside, and kaempferol-3-O-rutinoside by UPLC-MS/MS, derived from the vine of Tetrastigma hemsleyanum (TV), a traditional Chinese herb and food. TVF exhibited outstanding anti-cancer abilities at the in vitro and in vivo level, and markedly triggered apoptosis via the Bax/Bcl-2/caspase-9/caspase-3 pathway. The intrinsic mechanism study illustrated that TVF might induce apoptosis by activating autophagy by inhibiting the Akt-mTOR pathway, and the main component of TVF, quercetin-3-O-rutinoside, enabled THR308 site binding to block the phosphorylation of Akt, which was further evidenced by molecular docking computation. Our study reveals the excellent anti-cancer ability and inner mechanism of TVF, suggesting TVF as a potential candidate for clinical drug exploitation or dietary supplementation in cancer medication and prevention, providing a promising strategy for cancer chemotherapy.

Venetoclax response is enhanced by selective inhibitor of nuclear export compounds in hematologic malignancies

The selective inhibitor of nuclear export (SINE) compounds selinexor (KPT-330) and eltanexor (KPT-8602) are from a novel class of small molecules that target exportin-1 (XPO1 [CRM1]), an essential nucleo-cytoplasmic transport protein responsible for the nuclear export of major tumor suppressor proteins and growth regulators such as p53, p21, and p27. XPO1 also affects the translation of messenger RNAs for critical oncogenes, including MYC, BCL2, MCL1, and BCL6, by blocking the export of the translation initiation factor eIF4E. Early trials with venetoclax (ABT-199), a potent, selective inhibitor of BCL2, have revealed responses across a variety of hematologic malignancies. However, many tumors are not responsive to venetoclax. We used models of acute myeloid leukemia (AML) and diffuse large B-cell lymphoma (DLBCL) to determine in vitro and in vivo responses to treatment with venetoclax and SINE compounds combined. Cotreatment with venetoclax and SINE compounds demonstrated loss of viability in multiple cell lines. Further in vitro analyses showed that this enhanced cell death was the result of an increase in apoptosis that led to a loss of clonogenicity in methylcellulose assays, coinciding with activation of p53 and loss of MCL1. Treatment with SINE compounds and venetoclax combined led to a reduction in tumor growth in both AML and DLBCL xenografts. Immunohistochemical analysis of tissue sections revealed that the reduction in tumor cells was partly the result of an induction of apoptosis. The enhanced effects of this combination were validated in primary AML and DLBCL patient cells. Our studies reveal synergy with SINE compounds and venetoclax in aggressive hematologic malignancies and provide a rationale for pursuing this approach in a clinical trial.

Dioscorea deltoidea Leaf Extract (DDLE) Targets PI3K/AKT/mTOR Pathway and Inhibits Ovarian Cancer Cell Growth

Ovarian cancer is the malignant tumour of the female reproductive organ with highest mortality rate among all the types of gynaecological tumours. This study investigated the effect of Dioscorea deltoidea leaf extract (DDLE) on OV-90 and CAOV4 ovarian cancer cells. The results demonstrated that DDLE suppresses OV-90 and CAOV3 cell viability significantly in dose dependent manner. The OV-90 and CAOV3 cell viability were reduced to 24 and 27% respectively with 20 mg/mL DDLE treatment. Five mg/mL DDLE treatment of OV-90 and CAOV4 cells raised percentage of cells in G2-phase to 55.9 and 51.2%, respectively. In 5 mg/mL DDLE -treated OV-90 and CAOV4 cells a prominent suppression in cyclin-D1 and cyclin B1 proteins was observed in 48 h. The DDLE treatment promoted OV-90 and CAOV3 cell apoptosis to 34.65 and 29.89%, respectively. The Fas, FasL, cleaved caspase-3, and Bax levels were up-regulated markedly in the cells after DDLE treatment. Moreover, DDLE treatment suppressed p-mTOR, p-AKT and p-PI3K expression in OV-90 and CAOV3 cells. Thus, DDLE suppressed ovary cancer cell viability and elevated cell apoptosis. Inhibitory effect of DDLE on ovarian cancer cells is associated with targeting PI3K/AKT/mTOR pathway.

Cadmium triggers oxidative stress and mitochondrial injury mediated apoptosis in human extravillous trophoblast HTR-8/SVneo cells

Cadmium (Cd) is a bioaccumulative heavy metal element with potential placental toxicity during pregnancy. Up to now, however, the precise toxic effects of Cd on human placentae, particularly as they pertain to trophoblast cells remain obscure. We therefore sought to investigate the cytotoxic effects of Cd on human extravillous trophoblast HTR-8/SVneo cells and the mechanisms involved in the processes. Results in this present study showed that CdCl2 treatment significantly suppressed cell viability and induced noticeable oxidative stress in HTR-8/SVneo cells. Further studies showed that CdCl2 treatment caused distortion of mitochondrial structure, reduction of mitochondrial membrane potential (Δψm), DNA damage and G0/G1 phase arrest. Under the same condition, CdCl2 treatment increased Bax/Bcl-2 ratios by up-regulating Bax expression and down-regulating Bcl-2 expression, and activated apoptotic executive molecule caspase-3, which irreversibly induced HTR-8/SVneo cell apoptosis. N-acetyl-l-cysteine (NAC), ROS scavenger, significantly attenuated CdCl2-caused mitochondrial injury, DNA damage, G0/G1 phase arrest and apoptosis. In addition, in vivo assay suggested that CdCl2 induced trophoblast cells apoptosis but not other cells in mice placental tissue. Taken together, these data suggest that Cd selectively triggers oxidative stress and mitochondrial injury mediated apoptosis in trophoblast cells, which might contribute to placentae impairment and placental-related disorders after Cd exposure. These findings may provide new insights to understand adverse effects of Cd on placentae during pregnancy.

Mitochondria: The metabolic switch of cellular oncogenic transformation

Mitochondria, well recognized as the "powerhouse" of cells, are maternally inherited organelles with bacterial ancestry that play essential roles in a myriad of cellular functions. It has become profoundly evident that mitochondria regulate a wide array of cellular and metabolic functions, including biosynthetic metabolism, cell signaling, redox homeostasis, and cell survival. Correspondingly, defects in normal mitochondrial functioning have been implicated in various human malignancies. Cancer development involves the activation of oncogenes, inactivation of tumor suppressor genes, and impairment of apoptotic programs in cells. Mitochondria have been recognized as the site of key metabolic switches for normal cells to acquire a malignant phenotype. This review outlines the role of mitochondria in human malignancies and highlights potential aspects of mitochondrial metabolism that could be targeted for therapeutic development.