The deadly landscape of pro-apoptotic BCL-2 proteins in the outer mitochondrial membrane

Discovery of natural MCL1 inhibitors using pharmacophore modelling, QSAR, docking, ADMET, molecular dynamics, and DFT analysis

Mcl-1, a member of the Bcl-2 family, is a crucial regulator of apoptosis, frequently overexpressed in various cancers, including lung, breast, pancreatic, cervical, ovarian cancers, leukemia, and lymphoma. Its anti-apoptotic function allows tumor cells to evade cell death and contributes to drug resistance, making it an essential target for anticancer drug development. This study aimed to discover potent antileukemic compounds targeting Mcl-1. We selected diverse molecules from the BindingDB database to construct a structure-based pharmacophore model, which facilitated the virtual screening of 407,270 compounds from the COCONUT database. An e-pharmacophore model was developed using the co-crystallized inhibitor, followed by QSAR modeling to estimate IC50 values and filter compounds with predicted values below the median. The top hits underwent molecular docking and MMGBSA binding energy calculations against Mcl-1, resulting in the selection of two promising candidates for further ADMET analysis. DFT calculations assessed their electronic properties, confirming favorable reactivity profiles of the screened compounds. Predictions for physicochemical and ADMET properties aligned with expected bioactivity and safety. Molecular dynamics simulations further validated their strong binding affinity and stability, positioning them as potential Mcl-1 inhibitors. Our comprehensive computational approach highlights these compounds as promising antileukemic agents, with future in vivo and in vitro validation recommended for further confirmation.

Ethanol extract of Moschus attenuates glutamate-induced cytotoxicity in HT22 cells by regulating the Nrf2 and MAPK pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Moschus is a traditional Chinese materia medica for treating central nervous system disorders. Oxidative stress is a key pathogenic mechanism of Alzheimer's disease (AD) and serves as a critical bridge linking various pathological processes of AD. Previous studies have shown that Moschus can exert neuroprotective effects by inhibiting glutamate-induced neuronal cell damage. However, its underlying mechanisms remain unclear.

AIM OF THE STUDY

This study aimed to evaluate the effects and potential mechanisms of the ethanol extract of Moschus (EEM) on glutamate-induced oxidative damage in HT22 cells.

MATERIALS AND METHODS

The components of EEM were identified using GC-MS. An oxidative toxicity cell model was established by exposing HT22 cells to glutamate. Cell viability was assessed through CCK8 and LDH assays, and the modes of cell death were evaluated using FITC-Annexin V staining and TUNEL assays. Intracellular and mitochondrial ROS levels were measured with DCFH-DA and MitoSOX Red probes. Intracellular Ca2+ levels were measured with the Fluo-4 AM fluorescent probe. Mitochondrial function was analyzed using the JC-1 fluorescent probe. Protein expression levels of Bid, Calpain-1, Bax, Bcl-2, AIF, P-ERK, ERK, P-JNK, JNK, P-P38, P38, Nrf2, HO-1, Keap1, and NQO-1 were analyzed through western blotting. The distribution of AIF and Nrf2 in the cytoplasm and nucleus was examined through immunofluorescence staining.

RESULTS

Using GC-MS, 18 major components were identified in EEM. EEM significantly inhibited apoptosis, reduced ROS generation, and alleviated Ca2+ overload. EEM restored mitochondrial dysfunction by regulating the expression of mitochondria-related apoptotic proteins, including the downregulation of Calpain-1 and Bax, upregulation of Bid and Bcl-2, and inhibition of AIF nuclear translocation. EEM inhibited MAPK phosphorylation while activating the Nrf2/Keap1 signaling pathway.

CONCLUSIONS

Our study shows that EEM protects HT22 cells from glutamate-induced damage by regulating the MAPK and Nrf2 pathways, effectively reducing oxidative stress and apoptosis. In summary, this study first demonstrates at the cellular level that EEM exerts neuroprotective effects by modulating the MAPK and Nrf2 pathways. These findings provide new insights into the mechanism of Moschus against AD and establish a foundation for its potential application in AD.

An unconventional autophagic pathway that inhibits ATP secretion during apoptotic cell death

Mobilisation of Damage-Associated Molecular Patterns (DAMPs) determines the immunogenic properties of apoptosis, but the mechanisms that control DAMP exposure are still unclear. Here we describe an unconventional autophagic pathway that inhibits the release of ATP, a critical DAMP in immunogenic apoptosis, from dying cells. Mitochondrial BAK activated by BH3-only molecules interacts with prohibitins and stomatin-1 through its latch domain, indicating the existence of an interactome specifically assembled by unfolded BAK. This complex engages the WD40 domain of the autophagic effector ATG16L1 to induce unconventional autophagy, and the resulting LC3-positive vesicles contain ATP. Functional interference with the pathway increases ATP release during cell death, reduces ATP levels remaining in the apoptotic bodies, and improves phagocyte activation. These results reveal that an unconventional component of the autophagic burst that often accompanies apoptosis sequesters intracellular ATP to prevent its release, thus favouring the immunosilent nature of apoptotic cell death.

Harnessing natural saponins: Advancements in mitochondrial dysfunction and therapeutic applications

BACKGROUND

Mitochondrial dysfunction plays a crucial role in the development of a variety of diseases, notably neurodegenerative disorders, cardiovascular diseases, metabolic syndrome, and cancer. Natural saponins, which are intricate glycosides characterized by steroidal or triterpenoid structures, have attracted interest due to their diverse pharmacological benefits, including anti-inflammatory, antiviral, and anti-aging effects.

PURPOSE

This review synthesizes recent advancements in understanding mitochondrial dysfunction and explores how saponins can modulate mitochondrial function. It focuses on their potential applications in neuroprotection, cardiovascular health, and oncology.

STUDY DESIGN

The review incorporates a comprehensive literature analysis, highlighting the interplay between saponins and mitochondrial signaling pathways. Specific attention is given to the effects of saponins like ginsenoside Rg2 and 20(S)-protopanaxatriol on mitophagy and their neuroprotective, anti-aging, and synergistic therapeutic effects when combined.

METHODS

We conducted a comprehensive review of current research and clinical trials using PubMed, Google Scholar, and SciFinder databases. The search focused on saponins' role in mitochondrial function and their therapeutic effects, including "saponins", "mitochondria" and "mitochondrial function". The analysis primarily focused on articles published between 2011 and 2024.

RESULTS

The findings indicate that certain saponins can enhance mitophagy and modulate mitochondrial signaling pathways, showing promise in neuroprotection and anti-aging. Additionally, combinations of saponins have demonstrated synergistic effects in myocardial protection and cancer therapy, potentially improving therapeutic outcomes.

CONCLUSION

Although saponins exhibit significant potential in modulating mitochondrial functions and developing innovative therapeutic strategies, their clinical applications are constrained by low bioavailability. Rigorous clinical trials are essential to translate these findings into effective clinical therapies, ultimately improving patient outcomes through a deeper understanding of saponins' impact on mitochondrial function.

Biomimetic celastrol nanocrystals with enhanced efficacy and reduced toxicity for suppressing breast cancer invasion and metastasis

Breast cancer and its lung metastases pose significant threats to women's health worldwide, impacting their quality of life. Although several therapeutic strategies against breast cancer have been developed, they often cause serious side effects due to their high toxicity and low specificity. Therefore, novel therapeutic strategies that offer potent anti-tumor activity with minimal toxicity are urgently needed to combat the threat of breast cancer and lung metastases. Celastrol (Cela), a triterpenoid extracted from Tripterygium wilfordii, exerts anti-tumor effects by inhibiting tumor angiogenesis as well as tumor cell proliferation, invasion, and metastasis. However, its poor solubility and potential for severe organ toxicity hinder its clinical application. Therefore, in this study, we prepared Cela nanocrystals (Cela-NCs), which effectively increased the solubility of Cela and improved its bioavailability. Subsequently, Cela-NCs were encapsulated within the cell membrane (CCM) derived from breast cancer cells to generate CCM/Cela-NCs and leverage the homologous targeting ability of the CCM. Notably, CCM/Cela-NCs showed immune evasion and could homologously target tumor cells. Both in vitro and in vivo, CCM/Cela-NCs could effectively inhibit the growth and metastasis of breast cancer cells. They also exerted minimal hepatotoxicity in mice during treatment. In conclusion, this Cela-based biomimetic strategy that exploits the biological properties of tumor cells offers a new idea for the effective treatment of breast cancer and its lung metastasis.

Synergistic anticancer effects of cisplatin and phenolic aglycones of the aerial part of Rumex dentatus L. in tongue squamous cell carcinoma: insights from network pharmacology and biological verification

BACKGROUND

Oral squamous cell carcinoma (OSCC) ranks as the sixth most common malignancy globally. Cisplatin is the standard chemotherapy for OSCC, but resistance often reduces its efficacy, necessitating new treatments with fewer side effects. Rumex dentatus L., from the Polygonaceae family, is known for its medicinal properties, but its anticancer potential has not been thoroughly explored. This study aimed to investigate the synergy between cisplatin and an extract from the aerial parts of R. dentatus L. in treating tongue carcinoma (HNO97) in vitro, using network pharmacology, biological verification, and phytochemical analysis.

METHODS

The study included UPLC-ESI-MS/MS analysis, cytotoxicity assays, cell cycle analysis, apoptosis assessment, and RT-qPCR for gene expression of Bcl2, p53, and ATG7. Potential targets were identified, and mechanisms of action were examined through online databases and enrichment analyses.

RESULTS

The R. dentatus L. extract contained 14 phenolic aglycons. Combining cisplatin and R. dentatus L. was more effective in inhibiting proliferation, inducing cell cycle arrest and apoptosis, and reducing autophagy in HNO97 cells than cisplatin alone. KEGG analysis indicated that the drug combination might work through pathways like PI3K-Akt signaling, microRNAs in cancer, and EGFR tyrosine kinase inhibitor resistance.

CONCLUSIONS

Combining cisplatin with R. dentatus L. may be a promising approach for treating tongue carcinoma by affecting multiple pathways, providing a new perspective for developing more effective treatments for OSCC.

SLC25A21 correlates with the prognosis of adult acute myeloid leukemia through inhibiting the growth of leukemia cells via downregulating CXCL8

In recent years, targeting mitochondrial apoptosis has emerged as a promising therapeutic strategy for Acute Myeloid Leukemia (AML). The SLC25 family of mitochondrial carriers plays a critical role in maintaining mitochondrial function and regulating apoptosis. However, the role of SLC25A21, an oxodicarboxylate carrier, in AML progression and its potential as a prognostic biomarker remain underexplored. This study aimed to further investigate the role, molecular mechanism, and potential clinical value of SLC25A21 in AML progression. The transcript levels of SLC25A21 in bone marrow specimens were analyzed using real-time quantitative polymerase chain reaction. The correlation between SLC25A21 expression and the prognosis of AML was assessed through survival analysis. Findings revealed that SLC25A21 was downregulated in adult AML, and the low expression of SLC25A21 was correlated with worse prognosis for AML patients. Furthermore, overexpression of SLC25A21 inhibited cell proliferation and cell cycle progression, and was correlated with apoptosis through mitochondrial apoptosis signaling pathway. C-X-C motif chemokine ligand 8 (CXCL8) was identified as a downstream target of SLC25A21. These functions of SLC25A21 could be rescued by the overexpression of CXCL8. Moreover, SLC25A21 overexpression significantly suppressed the growth of xenograft tumors. In conclusion, the low SLC25A21 expression is correlated with poor clinical outcome. The overexpression of SLC25A21 inhibited the AML cell survival and proliferation by dysregulating the expression of CXCL8. SLC25A21 might be a potential prognostic marker and a treatment target for AML.

Japanese encephalitis virus infection induces mitochondrial-mediated apoptosis through the proapoptotic protein BAX

The Japanese encephalitis virus (JEV), a zoonotic flavivirus, is Asia's primary cause of viral encephalitis. JEV induces apoptosis in a variety of cells; however, the precise mechanisms underlying this apoptosis resulting from JEV infection remain to be elucidated. Our previous studies showed that the proapoptosis gene BAX may have a role in JEV proliferation. In this study, we constructed a PK-15 cell line (BAX.KO) with a knockout of the BAX gene using CRISPR/Cas9. The knockout of the BAX gene effectively inhibited the proliferation of JEV, resulting in a 39.9% decrease in viral protein levels, while BAX overexpression produced the opposite effect. We confirmed that JEV induces apoptosis of PK-15 using 4',6-diamidino-2-phenylindole (DAPI) staining and Annexin V-FITC/PI staining. Furthermore, we found that the phosphorylation of P53 and the expression levels of BAX, NOXA, PUMA, and cleaved-caspase-3/9 were significantly upregulated after JEV infection. Moreover, we found that JEV infection not only caused mitochondrial damage, the release of mitochondrial cytochrome C (Cyt C), and the downregulation of the apoptosis-inhibiting protein BCL-2 but also reduced the mitochondrial membrane potential (MOMP) and the accumulation of intracellular reactive oxygen species (ROS). These factors collectively encourage the activation of the mitochondrial apoptosis pathway. In contrast, BAX gene knockout significantly reduces the apoptotic changes caused by JEV infection. Treatment with the caspase3 inhibitor attenuated JEV-induced viral proliferation and release, leading to a decrease in viral protein levels of 46% in PK-15 cells and 30% in BAX.KO cells. In conclusion, this study clarified the molecular mechanisms of JEV-induced apoptosis and provided a theoretical basis for revealing the pathogenic mechanisms of JEV infection.

The minimal membrane requirements for BAX-induced pore opening upon exposure to oxidative stress

Perforation of the outer mitochondrial membrane triggered by BAX and facilitated by its main activator cBID is a fundamental process in cell apoptosis. Here, we employ a newly designed correlative approach based on a combination of a fluorescence cross correlation binding with a calcein permeabilization assay to understand the involvement of BAX in pore formation under oxidative stress conditions. To mimic the oxidative stress, we enriched liposomal membranes by phosphatidylcholines with truncated sn-2 acyl chains terminated by a carboxyl or aldehyde moiety. Our observations revealed that oxidative stress enhances proapoptotic conditions involving accelerated pore-opening kinetics. This enhancement is achieved through increased recruitment of BAX to the membrane and facilitation of BAX membrane insertion. Despite these effects, the fundamental mechanism of pore formation remained unchanged, suggesting an all-or-none mechanism. In line with this mechanism, we demonstrated that the minimal number of BAX molecules at the membrane necessary for pore formation remains constant regardless of BAX activation by cBID or the presence of oxidized lipids. Overall, our findings give a comprehensive picture of the molecular mechanisms underlying apoptotic pore formation and highlight the selective amplifying role of oxidized lipids in triggering formation of membrane pores.

Natural products reverse cisplatin resistance in the hypoxic tumor microenvironment

Cisplatin is one of the most commonly used drugs for cancer treatment. Despite much progress in improving patient outcomes, many patients are resistant to cisplatin-based treatments, leading to limited treatment efficacy and increased treatment failure. The fact that solid tumors suffer from hypoxia and an inadequate blood supply in the tumor microenvironment has been widely accepted for decades. Numerous studies have shown that a hypoxic microenvironment significantly reduces the sensitivity of tumor cells to cisplatin. Therefore, understanding how hypoxia empowers tumor cells with cisplatin resistance is essential. In the fight against tumors, developing innovative strategies for overcoming drug resistance has attracted widespread interest. Natural products have historically made major contributions to anticancer drug research due to their obvious efficacy and abundant candidate resources. Intriguingly, natural products show the potential to reverse chemoresistance, which provides new insights into cisplatin resistance in the hypoxic tumor microenvironment. In this review, we describe the role of cisplatin in tumor therapy and the mechanisms by which tumor cells generate cisplatin resistance. Subsequently, we call attention to the linkage between the hypoxic microenvironment and cisplatin resistance. Furthermore, we summarize known and potential natural products that target the hypoxic tumor microenvironment to overcome cisplatin resistance. Finally, we discuss the current challenges that limit the clinical application of natural products. Understanding the link between hypoxia and cisplatin resistance is the key to unlocking the full potential of natural products, which will serve as new therapeutic strategies capable of overcoming resistance.

Revolutionizing osteoarthritis treatment: How mesenchymal stem cells hold the key

Osteoarthritis (OA) is a multifaceted disease characterized by imbalances in extracellular matrix metabolism, chondrocyte and synoviocyte senescence, as well as inflammatory responses mediated by macrophages. Although there have been notable advancements in pharmacological and surgical interventions, achieving complete remission of OA remains a formidable challenge, oftentimes accompanied by significant side effects. Mesenchymal stem cells (MSCs) have emerged as a promising avenue for OA treatment, given their ability to differentiate into chondrocytes and facilitate cartilage repair, thereby mitigating the impact of an inflammatory microenvironment induced by macrophages. This comprehensive review aims to provide a concise overview of the diverse roles played by MSCs in the treatment of OA, while elucidating the underlying mechanisms behind these contributions. Specifically, the roles include: (a) Promotion of chondrocyte and synoviocyte regeneration; (b) Inhibition of extracellular matrix degradation; (c) Attenuating the macrophage-induced inflammatory microenvironment; (d) Alleviation of pain. Understanding the multifaceted roles played by MSCs in OA treatment is paramount for developing novel therapeutic strategies. By harnessing the regenerative potential and immunomodulatory properties of MSCs, it may be possible to devise more effective and safer approaches for managing OA. Further research and clinical studies are warranted to optimize the utilization of MSCs and realize their full potential in the field of OA therapeutics.

Regulation of cardiac fibroblast cell death by unfolded protein response signaling

The endoplasmic reticulum (ER) is a tightly regulated organelle that requires specific environmental properties to efficiently carry out its function as a major site of protein synthesis and folding. Embedded in the ER membrane, ER stress sensors inositol-requiring enzyme 1 (IRE1), protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK), and activating transcription factor 6 (ATF6) serve as a sensitive quality control system collectively known as the unfolded protein response (UPR). In response to an accumulation of misfolded proteins, the UPR signals for protective mechanisms to cope with the cellular stress. Under prolonged unstable conditions and an inability to regain homeostasis, the UPR can shift from its original adaptive response to mechanisms leading to UPR-induced apoptosis. These UPR signaling pathways have been implicated as an important feature in the development of cardiac fibrosis, but identifying effective treatments has been difficult. Therefore, the apoptotic mechanisms of UPR signaling in cardiac fibroblasts (CFs) are important to our understanding of chronic fibrosis in the heart. Here, we summarize the maladaptive side of the UPR, activated downstream pathways associated with cell death, and agents that have been used to modify UPR-induced apoptosis in CFs.

Chemical modulation of cytosolic BAX homodimer potentiates BAX activation and apoptosis

The BCL-2 family protein BAX is a major regulator of physiological and pathological cell death. BAX predominantly resides in the cytosol in a quiescent state and upon stress, it undergoes conformational activation and mitochondrial translocation leading to mitochondrial outer membrane permeabilization, a critical event in apoptosis execution. Previous studies reported two inactive conformations of cytosolic BAX, a monomer and a dimer, however, it remains unclear how they regulate BAX. Here we show that, surprisingly, cancer cell lines express cytosolic inactive BAX dimers and/or monomers. Expression of inactive dimers, results in reduced BAX activation, translocation and apoptosis upon pro-apoptotic drug treatments. Using the inactive BAX dimer structure and a pharmacophore-based drug screen, we identify a small-molecule modulator, BDM19 that binds and activates cytosolic BAX dimers and prompts cells to apoptosis either alone or in combination with BCL-2/BCL-XL inhibitor Navitoclax. Our findings underscore the role of the cytosolic inactive BAX dimer in resistance to apoptosis and demonstrate a strategy to potentiate BAX-mediated apoptosis.

Extracellular nanovesicles produced by Bacillus licheniformis: A potential anticancer agent for breast and lung cancer

Cancer is a major public burden and leading cause of death worldwide; furthermore, it is a significant barrier to increasing life expectancy in most countries of the world. Among various types of cancers, breast and lung cancers lead to significant mortality in both males and females annually. Bacteria-derived products have been explored for their use in cancer therapy. Although bacteria contain significant amounts of anticancer substances, attenuated bacteria may still pose a potential risk for infection owing to the variety of immunomodulatory molecules present in the parental bacteria; therefore, non-cellular bacterial extracellular vesicles (BEVs), which are naturally non-replicating, safer, and are considered to be potential anticancer agents, are preferred for cancer therapy. Gram-positive bacteria actively secrete cytoplasmic membrane vesicles that are spherical and vary between 10 and 400 nm in size. However, no studies have considered cytoplasmic membrane vesicles derived from Bacillus licheniformisin cancer treatment. In this study, we investigated the potential use of B. licheniformis extracellular nanovesicles (BENVs) as therapeutic agents to treat cancer. Purified BENVs from the culture supernatant of B. licheniformis using ultracentrifugation and ExoQuick were characterized using a series of analytical techniques. Human breast cancer cells (MDA-MB-231) and lung cancer cells (A549) were treated with different concentrations of purified BENVs, which inhibited the cell viability and proliferation, and increased cytotoxicity in a dose-dependent manner. To elucidate the mechanism underlying the anticancer activity of BENVs, the oxidative stress markers such as reactive oxygen species (ROS) and glutathione (GSH) levels were measured. The ROS levels were significantly higher in BENV-treated cells, whereas the GSH levels were markedly reduced. Cells treated with BENVs, doxorubicin (DOX), or a combination of BENVs and DOX showed significantly increased expression of p53, p21, caspase-9/3, and Bax, and concomitantly decreased expression of Bcl-2. The combination of BENVs and doxorubicin enhanced mitochondrial dysfunction, DNA damage, and apoptosis. To our knowledge, this is the first study to determine the anticancer properties of BENVs derived from industrially significant probacteria on breast and lung cancer cells.

Bcl-2 Antagonist Obatoclax Reactivates Latent HIV-1 via the NF-κB Pathway and Induces Latent Reservoir Cell Apoptosis in Latently Infected Cells

The implementation of combined antiretroviral therapy (cART) has rendered HIV-1 infection clinically manageable and efficiently improves the quality of life for patients with AIDS. However, the persistence of a latent HIV-1 reservoir is a major obstacle to achieving a cure for AIDS. A "shock and kill" strategy aims to reactivate latent HIV and then kill it by the immune system or cART drugs. To date, none of the LRA candidates has yet demonstrated effectiveness in achieving a promising functional cure. Interestingly, the phosphorylation and activation of antiapoptotic Bcl-2 protein induce resistance to apoptosis during HIV-1 infection and the reactivation of HIV-1 latency in central memory CD4+ T cells from HIV-1-positive patients. Therefore, a Bcl-2 antagonist might be an effective LRA candidate for HIV-1 cure. In this study, we reported that a pan-Bcl-2 antagonist obatoclax induces HIV-1 reactivation in latently infected cell lines in vitro and in PBMCs/CD4+ T cells of HIV-infected individuals ex vivo. Obatoclax promotes HIV-1 transcriptional initiation and elongation by regulating the NF-κB pathway. Obatoclax activates caspase 8 and does not induce the phosphorylation of the antiapoptotic protein Bcl-2 in latent HIV-1 infected cell lines. More importantly, it preferentially induces apoptosis in latently infected cells. In addition, obatoclax exhibited potent anti-HIV-1 activity on target cells. The abilities to reactivate latent HIV-1 reservoirs, inhibit HIV-1 infection, and induce HIV-1 latent cell apoptosis make obatoclax worth investigating for development as an ideal LRA for use in the "shock and kill" approach.

The mechanisms of action of mitochondrial targeting agents in cancer: inhibiting oxidative phosphorylation and inducing apoptosis

The tumor microenvironment affects the structure and metabolic function of mitochondria in tumor cells. This process involves changes in metabolic activity, an increase in the amount of reactive oxygen species (ROS) in tumor cells compared to normal cells, the production of more intracellular free radicals, and the activation of oxidative pathways. From a practical perspective, it is advantageous to develop drugs that target mitochondria for the treatment of malignant tumors. Such drugs can enhance the selectivity of treatments for specific cell groups, minimize toxic effects on normal tissues, and improve combinational treatments. Mitochondrial targeting agents typically rely on small molecule medications (such as synthetic small molecules agents, active ingredients of plants, mitochondrial inhibitors or autophagy inhibitors, and others), modified mitochondrial delivery system agents (such as lipophilic cation modification or combining other molecules to form targeted mitochondrial agents), and a few mitochondrial complex inhibitors. This article will review these compounds in three main areas: oxidative phosphorylation (OXPHOS), changes in ROS levels, and endogenous oxidative and apoptotic processes.

Role of YY1 in the Regulation of Anti-Apoptotic Gene Products in Drug-Resistant Cancer Cells

Cancer is a leading cause of death among the various diseases encountered in humans. Cancer is not a single entity and consists of numerous different types and subtypes that require various treatment regimens. In the last decade, several milestones in cancer treatments were accomplished, such as specific targeting agents or revitalizing the dormant anti-tumor immune response. These milestones have resulted in significant positive clinical responses as well as tumor regression and the prolongation of survival in subsets of cancer patients. Hence, in non-responding patients and non-responding relapsed patients, cancers develop intrinsic mechanisms of resistance to cell death via the overexpression of anti-apoptotic gene products. In parallel, the majority of resistant cancers have been reported to overexpress a transcription factor, Yin Yang 1 (YY1), which regulates the chemo-immuno-resistance of cancer cells to therapeutic anticancer cytotoxic agents. The relationship between the overexpression of YY1 and several anti-apoptotic gene products, such as B-cell lymphoma 2 protein (Bcl-2), B-cell lymphoma extra-large (Bcl-xL), myeloid cell leukemia 1 (Mcl-1) and survivin, is investigated in this paper. The findings demonstrate that these anti-apoptotic gene products are regulated, in part, by YY1 at the transcriptional, epigenetic, post-transcriptional and translational levels. While targeting each of the anti-apoptotic gene products individually has been examined and clinically tested for some, this targeting strategy is not effective due to compensation by other overexpressed anti-apoptotic gene products. In contrast, targeting YY1 directly, through small interfering RNAs (siRNAs), gene editing or small molecule inhibitors, can be therapeutically more effective and generalized in YY1-overexpressed resistant cancers.

The Peptide Salamandrin-I Modulates Components Involved in Pyroptosis and Induces Cell Death in Human Leukemia Cell Line HL-60

Amphibian secretions have been extensively investigated for the production of bioactive molecules. Salamandrin-I is an antioxidant peptide, isolated from the skin secretion of the fire salamander, that has induced no toxicity in microglia or erythrocytes. Importantly, the administration of antioxidants may constitute an adequate therapeutic approach to cancer treatment. Here, with the purpose of better characterizing the therapeutic potential of salamandrin-I, we investigated whether this antioxidant peptide also exerts anticancer activity, using the human leukemia cell line HL-60 as a cancer model. Salamandrin-I treatment induced a significant reduction in HL-60 proliferation, which was accompanied by cell cycle arrest. Furthermore, the peptide-induced cell death showed a significant increase in the LDH release in HL-60 cells. The cellular toxicity exerted by salamandrin-I is possibly related to pyroptosis, since the HL-60 cells showed loss of mitochondrial membrane potential and hyperexpression of inflammasome components following the peptide treatment. This is the first demonstration of the anticancer potential of the salamandrin-I peptide. Such results are important, as they offer relevant insights into the field of cancer therapy and allow the design of future bioactive molecules using salamandrin-I as a template.

Membrane interactions of apoptotic inhibitor Bcl-xL: What can be learned using fluorescence spectroscopy

Permeabilization of the mitochondrial outer membrane-a point of no return in apoptotic regulation-is tightly controlled by proteins of the Bcl-2 family. Apoptotic inhibitor Bcl-xL is an important member of this family, responsible for blocking the permeabilization, and is also a promising target for anti-cancer drugs. Bcl-xL exists in the following conformations, each believed to play a role in the inhibition of apoptosis: (i) a soluble folded conformation, (ii) a membrane-anchored (by its C-terminal α8 helix) form, which retains the same fold as in solution and (iii) refolded membrane-inserted conformations, for which no structural data are available. In this review, we present the summary of the application of various methods of fluorescence spectroscopy for studying membrane interaction of Bcl-xL, and specifically the formation of the refolded inserted conformation. We discuss the application of environment-sensitive probes, Förster resonance energy transfer, fluorescence correlation spectroscopy, and fluorescent quenching for structural, thermodynamic, and functional characterization of protein-lipid interactions, which can benefit studies of other members of Bcl-2 (e.g., Bax, BAK, Bid). The conformational switching between various conformations of Bcl-xL depends on the presence of divalent cations, pH and lipid composition. This insertion-refolding transition also results in the release of the BH4 regulatory domain from the folded structure of Bcl-xL, which is relevant to the lipid-regulated conversion between canonical and non-canonical modes of apoptotic inhibition.

MicroRNA-582-5p targeting Creb1 modulates apoptosis in cardiomyocytes hypoxia/reperfusion-induced injury

BACKGROUND

Myocardial ischemia-reperfusion injury (MIRI) caused by the reperfusion therapy of myocardial ischemic diseases is a kind of major disease that threatens human health and lives severely. There are lacking of effective therapeutic measures for MIRI. MicroRNAs (miRNAs) are abundant in mammalian species and play a critical role in the initiation, promotion, and progression of MIRI. However, the biological role and molecular mechanism of miRNAs in MIRI are not entirely clear.

METHODS

We used bioinformatics analysis to uncover the significantly different miRNA by analyzing transcriptome sequencing data from myocardial tissue in the mouse MIRI model. Multiple miRNA-related databases, including miRdb, PicTar, and TargetScan were used to forecast the downstream target genes of the differentially expressed miRNA. Then, the experimental models, including male C57BL/6J mice and HL-1 cell line, were used for subsequent experiments including quantitative real-time polymerase chain reaction analysis, western blot analysis, hematoxylin and eosin staining, flow cytometry, luciferase assay, gene interference, and overexpression.

RESULTS

MiR-582-5p was found to be differentially upregulated from the transcriptome sequencing data. The elevated levels of miR-582-5p were verified in MIRI mice and hypoxia/reperfusion (H/R)-induced HL-1 cells. Functional experiments revealed that miR-582-5p promoted apoptosis of H/R-induced HL-1 cells via downregulating cAMP-response element-binding protein 1 (Creb1). The inhibiting action of miR-582-5p inhibitor on H/R-induced apoptosis was partially reversed after Creb1 interference.

CONCLUSIONS

Collectively, the research findings reported that upregulation of miR-582-5p promoted H/R-induced cardiomyocyte apoptosis by inhibiting Creb1. The potential diagnostic and therapeutic strategies targeting miR-582-5p and Creb1 could be beneficial for the MIRI treatment.

The role of BCL-2 family proteins in regulating apoptosis and cancer therapy

Apoptosis, as a very important biological process, is a response to developmental cues or cellular stress. Impaired apoptosis plays a central role in the development of cancer and also reduces the efficacy of traditional cytotoxic therapies. Members of the B-cell lymphoma 2 (BCL-2) protein family have pro- or anti-apoptotic activities and have been studied intensively over the past decade for their importance in regulating apoptosis, tumorigenesis, and cellular responses to anticancer therapy. Since the inflammatory response induced by apoptosis-induced cell death is very small, at present, the development of anticancer drugs targeting apoptosis has attracted more and more attention. Consequently, the focus of this review is to summarize the current research on the role of BCL-2 family proteins in regulating apoptosis and the development of drugs targeting BCL-2 anti-apoptotic proteins. Additionally, the mechanism of BCL-2 family proteins in regulating apoptosis was also explored. All the findings indicate the potential of BCL-2 family proteins in the therapy of cancer.

Plasmodium infection suppresses colon cancer growth by inhibiting proliferation and promoting apoptosis associated with disrupting mitochondrial biogenesis and mitophagy in mice

BACKGROUND

Colon cancer is a common gastrointestinal tumor with a poor prognosis, and thus new therapeutic strategies are urgently needed. The antitumor effect of Plasmodium infection has been reported in some murine models, but it is not clear whether it has an anti-colon cancer effect. In this study, we investigated the anti-colon cancer effect of Plasmodium infection and its related mechanisms using a mouse model of colon cancer.

METHODS

An experimental model was established by intraperitoneal injection of Plasmodium yoelii 17XNL-infected erythrocytes into mice with colon cancer. The size of tumors was observed dynamically in mice, and the expression of Ki67 detected by immunohistochemistry was used to analyze tumor cell proliferation. Apoptosis was assessed by terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labeling (TUNEL) staining, and the expression of apoptosis-related proteins including Bax, Bcl-2, caspase-9, and cleaved caspase-3 was detected by western blot and immunohistochemistry, respectively. Transmission electron microscopy (TEM) was used to observe the ultrastructural change in colon cancer cells, and the expression of mitochondrial biogenesis correlative central protein, PGC-1α, and mitophagy relevant crucial proteins, PINK1/Parkin, were detected by western blot.

RESULTS

We found that Plasmodium infection reduced the weight and size of tumors and decreased the expression of Ki67 in colon cancer-bearing mice. Furthermore, Plasmodium infection promoted mitochondria-mediated apoptosis in colon cancer cells, as evidenced by the increased proportion of TUNEL-positive cells, the upregulated expression of Bax, caspase-9, and cleaved caspase-3 proteins, and the downregulated expression of Bcl-2 protein. In colon cancer cells, we found destroyed cell nuclei, swollen mitochondria, missing cristae, and a decreased number of autolysosomes. In addition, Plasmodium infection disturbed mitochondrial biogenesis and mitophagy through the reduced expression of PGC-1α, PINK1, and Parkin proteins in colon cancer cells.

CONCLUSIONS

Plasmodium infection can play an anti-colon cancer role in mice by inhibiting proliferation and promoting mitochondria-mediated apoptosis in colon cancer cells, which may relate to mitochondrial biogenesis and mitophagy.

Circ-GTF2I/miR-590-5p Axis Aggravates Myocardial Ischemia-Reperfusion Injury by Regulating Kelch Repeat and BTB Domain-Containing Protein 7

Purpose

We investigated the effect of the circular RNA (circRNA) general transcription factor IIi (GTF2I) on myocardial ischemia (MI) deterioration and neonatal rat cardiomyocyte damage.

Methods

The cell experiment was performed by using neonatal rat cardiomyocytes. Moreover, a hypoxia/reoxygenation treatment model was established. Cell Counting Kit-8 assay was conducted, and EdU cell proliferation was detected. Cell apoptosis was detected via flow cytometry and quantitative RT-PCR (RT-qPCR). Binding detection was performed through a double-luciferase reporter assay. Interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and lactate dehydrogenase (LDH) were detected via enzyme-linked immunosorbent assay (ELISA).

Results

Compared with that in the sham and control groups, circ-GTF2I expression in MIRI and the hypoxia/reoxygenation treatment model was significantly upregulated in vivo and in vitro. The knockdown of circ-GTF2I relieved neonatal rat cardiomyocyte damage and MI. Further detection through the double-luciferase reporter assay confirmed that the binding site of circ-GTF2I to miR-590-5p and miR-590-5p was Kelch repeat and BTB domain-containing protein 7 (KBTBD7). ELISA and RT-qPCR results showed that circ-GTF2I induced the abnormal expressions of IL-6 TNF-α, LDH, Bax, Bcl-2, and Cyt-c in MIRI and the hypoxia/reoxygenation treatment models by regulating miR-590-5p and the heart development transcription factor KBTBD7.

Conclusions

CircRNA circ-GTF2I aggravated MIRI and neonatal rat cardiomyocyte damage in vivo and in vitro by regulating miR-590-5p and the heart development transcription factor KBTBD7.

Scopoletin protects retinal ganglion cells 5 from high glucose-induced injury in a cellular model of diabetic retinopathy via ROS-dependent p38 and JNK signaling cascade

The protective activity of scopoletin (SPT) against glucose-induced cataract has been attributed to attenuation of aldose reductase activity and oxidative stress in a rat model. The present investigation was aimed to study the protective effect and mechanism of SPT in retinal ganglia cells (RGC) under oxidative stress and apoptosis induced by hyperglycemia. The RGC-5 cells were pre-conditioned with variable SPT concentrations for 6 hours and then subjected to hyperglycemia for 48 hours. The cell viability, mito- chondrial membrane potential (MMP) and oxidative stress markers were quantified. Western blotting was employed to screen the expression of mitogen-activated protein kinase (MAPK) and various apoptosis related proteins. SPT blocked the high-glucose induced cell injury and normalized the mitochondrial functioning via lowering the loss of MMP and release of cytochrome c. Pretreatment with SPT suppressed the enhanced ROS, malondialdehyde, and protein carbonyl content triggered by high-glucose exposure in RGC-5 cells. SPT normalized the apoptotic proteins in RGC-5 cells. The phosphorylation of c-Jun N-terminal kinases (JNK) and p38 MAPK in RGC-5 due to hyperglycemia was attenuated by SPT. Overall, SPT exhibited a protective effect in RGC-5 cells exposed to a high-glucose environment via its antioxidant efficacy, inhibition of apoptosis and modulation of the ROS-dependent p38/JNK signaling cascade.

Physiological and pharmacological modulation of BAX

Bcl-2-associated X protein (BAX) is a critical executioner of mitochondrial regulated cell death through its lethal activity of permeabilizing the mitochondrial outer membrane (MOM). While the physiological function of BAX ensures tissue homeostasis, dysregulation of BAX leads to aberrant cell death. Despite BAX being a promising therapeutic target for human diseases, historically the development of drugs has focused on antiapoptotic BCL-2 proteins, due to challenges in elucidating the mechanism of BAX activation and identifying druggable surfaces of BAX. Here, we discuss recent studies that have provided structure-function insights and identified regulatory surfaces that control BAX activation. Moreover, we emphasize the development of small molecule orthosteric, allosteric, and oligomerization modulators that provide novel opportunities for biological investigation and progress towards drugging BAX.

Catalpol alleviates myocardial ischemia reperfusion injury by activating the Nrf2/HO-1 signaling pathway

PURPOSE

Myocardial ischemia/reperfusion injury (MI/RI) is a major problem in the clinical treatment of ischemic cardiomyopathy, and its specific underlying mechanisms are complicated and still unclear. A number of studies have indicated that the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxidase-1(HO-1) signaling pathway might serve as an important target for the management of MI/RI. Catalpol is a kind of iridoid glucoside that has been found to exhibit diverse anti-inflammatory and antioxidant properties. This study was aimed at investigating the role of Catalpol in targeting MI/RI and its related mechanisms in an oxygen-glucose deprivation/reoxygenation (OGD/R) model in vitro and a preclinical ischemia/reperfusion (I/R) model.

METHODS

This study using both in vitro and in vivo models investigated the possible role and underlying mechanisms used by Catalpol for modulating of MI/RI. The potential effects of Catalpol on the viability of cardiomyocytes were measured by cell counting kit-8 (CCK-8) assays. The phenotypes of myocardial injury, oxidative stress and inflammation markers were measured by western blot, immunofluorescence, enzyme-linked immunosorbent assay (ELISA) etc. Nrf2/HO-1 signaling pathway was detected by immunofluorescence and western blot analysis.

RESULTS

We found that Catalpol significantly suppressed the process of MI/RI and protected OGD/R-treated cardiomyocytes by inhibiting the various markers of inflammation and suppressing oxidative stress. Additionally, mechanistically it was also demonstrated that Catalpol could effectively activate Nrf2/HO-1 signaling pathway to suppress the damage caused by inflammation and oxidative stress in MI/RI.

CONCLUSION

In summary, the findings suggest that Catalpol exerted significant cardioprotective effects following myocardial ischemia, possibly through the activation of the Nrf2/HO-1 signaling pathway.

Death-Associated Protein Kinase 1 Promotes Alveolar Epithelial Cell Apoptosis and Ventilator-Induced Lung Injury Through P53 Pathway

OBJECTIVES

Mechanical stretch-induced alveolar epithelial cell (AEC) apoptosis participates in the onset of ventilator-induced lung injury (VILI). In this study, we explored whether death-associated protein kinase 1 (DAPK1) mediated cyclic stretch (CS)-induced AEC apoptosis and VILI though P53 pathway.

MATERIALS AND METHODS

AEC apoptosis was induced by CS using the FX-5000T Flexercell Tension Plus system. C57BL/6 mouse received high tidal volume ventilation to build VILI model. DAPK1 inhibitor, P53 inhibitor, or DAPK1 plasmid was used to regulate the expression of DAPK1 and P53, respectively. Flow cytometery was performed to assay cell apoptosis and the changes of mitochondrial membrane potential (MMP); immunoblotting was adopted to analyze related protein expression. The binding of related proteins was detected by coimmunoprecipitation; AEC apoptosis in vivo was determined by immunohistochemistry assay.

RESULTS

CS promoted AEC apoptosis, increased DAPK1 and P53 expression, and induced the binding of DAPK1 and P53; inhibition of DAPK1 or P53 reduced CS-induced AEC apoptosis, suppressed the expression of Bax, increased Bcl-2 level, and stabilized MMP; AEC apoptosis and the level of P53 were both increased after overexpressing of DAPK1. Moreover, DAPK1 plasmid transfection also promoted the expression of Bax and the change of MMP, but decreased the level of Bcl-2. Inhibition of DAPK1 or P53 in vivo alleviated high tidal volume ventilation-induced AEC apoptosis and lung injury.

CONCLUSIONS

DAPK1 contributes to AEC apoptosis and the onset of VILI though P53 and its intrinsic pro-apoptotic pathway. Inhibition of DAPK1 or P53 alleviates high tidal volume ventilation-induced lung injury and AEC apoptosis.

The role of mitochondrial apoptotic pathway in islet amyloid-induced β-cell death

Islet amyloid, formed by aggregation of human islet amyloid polypeptide (hIAPP), contributes to β-cell death in type 2 diabetes. We previously showed that extracellular hIAPP aggregates promote Fas-mediated β-cell apoptosis. Here, we tested if hIAPP aggregates can trigger the mitochondrial apoptotic pathway (MAP). hIAPP aggregation in Ad-hIAPP transduced INS-1 and human islet β-cells promoted cytochrome c release, caspase-9 activation and apoptosis, which were reduced by Bax inhibitor. Amyloid formation in hIAPP-expressing mouse islets during culture increased caspase-9 activation in β-cells. Ad-hIAPP transduced islets from CytcKA/KA and BaxBak βDKO mice (models of blocked MAP), had lower caspase-9-positive and apoptotic β-cells than transduced wild-type islets, despite comparable amyloid formation. Blocking Fas (markedly) and Bax or caspase-9 (modestly) reduced β-cell death induced by extracellular hIAPP aggregates. These findings suggest a role for MAP in amyloid-induced β-cell death and a potential strategy to reduce intracellular amyloid β-cell toxicity by blocking cytochrome c apoptotic function.

An Open Question: Is Non-Ionizing Radiation a Tool for Controlling Apoptosis-Induced Proliferation?

Non-ionizing radiation is commonly used in the clinical setting, despite its known ability to trigger oxidative stress and apoptosis, which can lead to damage and cell death. Although induction of cell death is typically considered harmful, apoptosis can also be beneficial in the right context. For example, cell death can serve as the signal for new tissue growth, such as in apoptosis-induced proliferation. Recent data has shown that exposure to non-ionizing radiation (such as weak static magnetic fields, weak radiofrequency magnetic fields, and weak electromagnetic fields) is able to modulate proliferation, both in cell culture and in living organisms (for example during tissue regeneration). This occurs via in vivo changes in the levels of reactive oxygen species (ROS), which are canonical activators of apoptosis. This review will describe the literature that highlights the tantalizing possibility that non-ionizing radiation could be used to manipulate apoptosis-induced proliferation to either promote growth (for regenerative medicine) or inhibit it (for cancer therapies). However, as uncontrolled growth can lead to tumorigenesis, much more research into this exciting and developing area is needed in order to realize its promise.

Yes, MAM!

Regulation of cell life and death by members of the BCL-2 family of proteins occurs at the mitochondria. Large portions of the mitochondria's outer membrane are found in tight approximation with the endoplasmic reticulum (ER), known as mitochondria-associated membranes (MAMs) or mitochondria-ER contact sites (MERCs). We recently reported that BOK is present within MAMs where it regulates Ca²⁺ transfer from the ER to the mitochondria, appropriate MAM components and MERC structure, and apoptosis.

Decrease in reproductive dysfunction using aflatoxin B1 exposure: a treatment with 3-indolepropionic acid in albino Wistar rat

We assessed the individual and combined consequence of 3-indolepropionic acid on aflatoxin B1-induced reproductive toxicity in rats. The experimental cohorts were dosed for four consecutive weeks with aflatoxin B1 (50 μg/kg), 3-indolepropionic acid (50 mg/kg), and both (aflatoxin B1: 50 μg/kg + 3-indolepropionic acid: 25 or 50 mg/kg), and the untreated control. Following sacrifice, biomarkers of testicular, epididymal and hypothalamic oxidative status, lipid peroxidation, reactive oxygen and nitrogen species, nitric oxide levels and myeloperoxidase activity were determined. Besides, tumour necrosis factor-alpha, Bcl-2 and Bax proteins were also assessed. Aflatoxin B1-induced testicular, epididymal and hypothalamic oxidative stress was significantly alleviated with 3-indolepropionic acid co-treatment. Also, increases in biomarkers of oxidative stress and reduced levels of antioxidants were abated significantly in rats co-treated with 3-indolepropionic acid. Aflatoxin B1-mediated increase in tumour necrosis factor-alpha, Bax, nitric oxide and myeloperoxidase activity in the examined organs was decreased significantly in aflatoxin B1 and 3-indolepropionic acid co-treated rats. Also, 3-indolepropionic acid dose dependently reduced Bcl-2 levels in the treated rats. The degree of aflatoxin B1-induced histopathological injuries was minimised in rats co-treated with 3-indolepropionic acid. Our results demonstrated that 3-indolepropionic acid protected experimental rats from aflatoxin B1-induced oxido-inflammatory stress and apoptotic response in the examined organs.

Structural Investigation of Orf Virus Bcl-2 Homolog ORFV125 Interactions with BH3-Motifs from BH3-Only Proteins Puma and Hrk

Numerous viruses have evolved sophisticated countermeasures to hijack the early programmed cell death of host cells in response to infection, including the use of proteins homologous in sequence or structure to Bcl-2. Orf virus, a member of the parapoxviridae, encodes for the Bcl-2 homolog ORFV125, a potent inhibitor of Bcl-2-mediated apoptosis in the host. ORFV125 acts by directly engaging host proapoptotic Bcl-2 proteins including Bak and Bax as well as the BH3-only proteins Hrk and Puma. Here, we determined the crystal structures of ORFV125 bound to the BH3 motif of proapoptotic proteins Puma and Hrk. The structures reveal that ORFV125 engages proapoptotic BH3 motif peptides using the canonical ligand binding groove. An Arg located in the structurally equivalent BH1 region of ORFV125 forms an ionic interaction with the conserved Asp in the BH3 motif in a manner that mimics the canonical ionic interaction seen in host Bcl-2:BH3 motif complexes. These findings provide a structural basis for Orf virus-mediated inhibition of host cell apoptosis and reveal the flexibility of virus encoded Bcl-2 proteins to mimic key interactions from endogenous host signalling pathways.

Comprehensive analysis of cytoskeleton regulatory genes identifies ezrin as a prognostic marker and molecular target in acute myeloid leukemia

PURPOSE

Despite great advances that have been made in the understanding of the molecular complexity of acute myeloid leukemia (AML), very little has been translated into new therapies. Here, we set out to investigate the impact of cytoskeleton regulatory genes on clinical outcomes and their potential as therapeutic targets in AML.

METHODS

Gene expression and clinical data were retrieved from The Cancer Genome Atlas (TCGA) AML study and used for survival and functional genomics analyses. For pharmacological tests, AML cells were exposed to ezrin (EZR) inhibitors and submitted to several cellular and molecular assays.

RESULTS

High EZR expression was identified as an independent marker of worse outcomes in AML patients from the TCGA cohort (p < 0.05). Functional genomics analyses suggested that EZR contributes to responses to stimuli and signal transduction pathways in leukemia cells. EZR pharmacological inhibition with NSC305787 and NSC668394 reduced viability, proliferation, autonomous clonal growth, and cell cycle progression in AML cells (p < 0.05). NSC305787 had a greater potency and efficiency than NSC668394 in leukemia models. At the molecular level, EZR inhibitors reduced EZR, S6 ribosomal protein and 4EBP1 phosphorylation, and induced PARP1 cleavage in AML cells. NSC305787, but not NSC668394, favored a gene network involving cell cycle arrest and apoptosis in Kasumi 1 AML cells.

CONCLUSIONS

From our data we conclude that EZR expression may serve as a prognostic factor in AML. Our preclinical findings indicate that ezrin inhibitors may be employed as a putative novel class of AML targeting drugs.

Pharmacological relevance of CDK inhibitors in Alzheimer's disease

Evidence suggests that cell cycle activation plays a role in the pathophysiology of neurodegenerative diseases. Alzheimer's disease is a progressive, terminal neurodegenerative disease that affects memory and other important mental functions. Intracellular deposition of Tau protein, a hyperphosphorylated form of a microtubule-associated protein, and extracellular aggregation of Amyloid β protein, which manifests as neurofibrillary tangles (NFT) and senile plaques, respectively, characterize this condition. In recent years, however, several studies have concluded that cell cycle re-entry is one of the key causes of neuronal death in the pathogenesis of Alzheimer's disease. The eukaryotic cell cycle is well-coordinated machinery that performs critical functions in cell replenishment, such as DNA replication, cell creation, repair, and the birth of new daughter cells from the mother cell. The complex interplay between the levels of various cyclins and cyclin-dependent kinases (CDKs) at different checkpoints is needed for cell cycle synchronization. CDKIs (cyclin-dependent kinase inhibitors) prevent cyclin degradation and CDK inactivation. Different external and internal factors regulate them differently, and they have different tissue expression and developmental functions. The checkpoints ensure that the previous step is completed correctly before starting the new cell cycle phase, and they protect against the transfer of defects to the daughter cells. Due to the development of more selective and potent ATP-competitive CDK inhibitors, CDK inhibitors appear to be on the verge of having a clinical impact. This avenue is likely to yield new and effective medicines for the treatment of cancer and other neurodegenerative diseases. These new methods for recognizing CDK inhibitors may be used to create non-ATP-competitive agents that target CDK4, CDK5, and other CDKs that have been recognized as important therapeutic targets in Alzheimer's disease treatment.

Methylglyoxal-Derived Advanced Glycation End Product (AGE4)-Induced Apoptosis Leads to Mitochondrial Dysfunction and Endoplasmic Reticulum Stress through the RAGE/JNK Pathway in Kidney Cells

Advanced glycation end products (AGEs) are formed via nonenzymatic reactions between reducing sugars and proteins. Recent studies have shown that methylglyoxal, a potent precursor for AGEs, causes a variety of biological dysfunctions, including diabetes, inflammation, renal failure, and cancer. However, little is known about the function of methylglyoxal-derived AGEs (AGE4) in kidney cells. Therefore, we verified the expression of endoplasmic reticulum (ER) stress-related genes and apoptosis markers to determine the effects of AGE4 on human proximal epithelial cells (HK-2). Moreover, our results showed that AGE4 induced the expression of apoptosis markers, such as Bax, p53, and kidney injury molecule-1, but downregulated Bcl-2 and cyclin D1 levels. AGE4 also promoted the expression of NF-κB, serving as a transcription factor, and the phosphorylation of c-Jun NH₂-terminal kinase (JNK), which induced cell apoptosis and ER stress mediated by the JNK inhibitor. Furthermore, AGE4 induced mitochondrial dysfunction by inducing the permeabilization of the mitochondrial membrane and ATP synthesis. Through in vitro and in vivo experiments, this study provides a new perspective on renal dysfunction with regard to the AGE4-induced RAGE /JNK signaling pathway, which leads to renal cell apoptosis via the imbalance of mitochondrial function and ER stress in kidney damage.

The protective effects of human umbilical cord mesenchymal stem cell-derived extracellular vesicles on cisplatin-damaged granulosa cells

OBJECTIVE

Long term exposure to gonadotoxic chemotherapy is becoming a major cause of premature ovarian failure/insufficiency (POF/POI) with the increasing cancer incidence among young women. The present study was designed to investigate the protective effects of human cord mesenchymal stem cells (HUCMSCs)-derived extracellular vesicles (EVs) on cisplatin (CDDP)-damaged granulosa cells (GCs) in vitro.

MATERIALS AND METHODS

EVs were obtained from supernatant of cultured HUCMSCs by ultracentrifugation method, purified by Sucrose density gradient centrifugation, and then were co-cultured with cisplatin-damaged GCs of 3-weeks female Sprague-Dawley (SD) rats. PKH26 labeled EVs could be observed in normal and CDDP-damaged GCs after 6 h co-culture.

RESULTS

The surviving GCs were significantly higher and apoptotic GCs were significantly lower in EVs + CDDP group compared with CDDP group. Meanwhile, the levels of E2 and StAR (the key gene related to synthesis of steroid hormone) were significantly higher in EVs + CDDP group compared with CDDP group. Furthermore, the mRNA expression of Caspase 3 was down-regulated significantly and the ratio of Bcl-2/Bax was up-regulated significantly in EVs + CDDP group. Moreover, the protective effect of EVs on CDDP-damaged GCs showed a dose-dependent effect.

CONCLUSION

HUCMSCs-derived EVs could become incorporated to CDDP-damaged GCs, and increase the number of living cells, therefore playing important roles in promoting resistance to cisplatin-induced GCs apoptosis and restoring synthesis and secretion of steroid hormone in GCs. This study might provide a theoretical and experimental basis for use of mesenchymal stem cells (MSCs) derived EVs instead of MSCs as a cell-free therapeutic strategy for the patients with POI induced by chemotherapeutic agents.

Natural products as pharmacological modulators of mitochondrial dysfunctions for the treatments of Alzheimer's disease: A comprehensive review

Alzheimer's disease (AD) is the most common progressive neurodegenerative disorder characterized by neuronal loss and cognitive impairment that harshly affect the elderly individuals. Currently, the available anti-AD pharmacological approaches are purely symptomatic to alleviate AD symptoms, and the curative effects of novel anti-AD drugs focused on Aβ target are disappointing. Hence, there is a tremendous need to adjust AD therapeutic targets and discover novel anti-AD agents. In AD, mitochondrial dysfunction gradually triggers neuronal death from different aspects and worsens the occurrence and progress of AD. Consequently, it has been proposed that the intervention of impaired mitochondria represents an attractive breakthrough point for AD treatments. Due to chemical diversity, poly-pharmacological activities, few adverse effects and multiple targeting, natural products (NPs) have been identified as a valuable treasure for drug discovery and development. Multiple lines of studies have scientifically proven that NPs display ameliorative benefits in AD treatment in relation to mitochondrial dysfunction. This review surveys the complicated implications for mitochondrial dysregulation and AD, and then summarizes the potentials of NPs and their underlying molecular mechanisms against AD via reducing or improving mitochondrial dysfunction. It is expected that this work may open the window to speed up the development of innovative anti-AD drugs originated from NPs and improve upcoming AD therapeutics.

Graphene oxide exacerbates dextran sodium sulfate-induced colitis via ROS/AMPK/p53 signaling to mediate apoptosis

Background

Graphene oxide (GO), a novel carbon-based nanomaterial, has promising applications in biomedicine. However, it induces potential cytotoxic effects on the gastrointestinal (GI) tract cells, and these effects have been largely uncharacterized. The present study aimed to explore the toxic effects of GO on the intestinal tract especially under pre-existing inflammatory conditions, such as inflammatory bowel disease (IBD), and elucidate underlying mechanisms.

Results

Our findings indicated that oral gavage of GO worsened acute colitis induced by 2.5% dextran sodium sulfate (DSS) in mice. In vitro, GO exacerbated DSS-induced inflammation and apoptosis in the FHC cell line, an ideal model of intestinal epithelial cells (IECs). Further, the potential mechanism underlying GO aggravated mice colitis and cell inflammation was explored. Our results revealed that GO treatment triggered apoptosis in FHC cells through the activation of reactive oxygen species (ROS)/AMP-activated protein kinase (AMPK)/p53 pathway, as evidenced by the upregulation of cytochrome c (Cytc), Bax, and cleaved caspase-3 (c-cas3) and the downregulation of Bcl-2. Interestingly, pretreatment with an antioxidant, N-acetyl-L-cysteine, and a specific inhibitor of AMPK activation, Compound C (Com.C), effectively inhibited GO-induced apoptosis in FHC cells.

Conclusions

Our data demonstrate that GO-induced IECs apoptosis via ROS/AMPK/p53 pathway activation accounts for the exacerbation of colitis in vivo and aggravation of inflammation in vitro. These findings provide a new insight into the pathogenesis of IBD induced by environmental factors. Furthermore, our findings enhance our understanding of GO as a potential environmental toxin, which helps delineate the risk of exposure to patients with disturbed intestinal epithelial barrier/inflammatory disorders such as IBD.

Eltrombopag directly inhibits BAX and prevents cell death

The BCL-2 family protein BAX has essential activity in mitochondrial regulation of cell death. While BAX activity ensures tissue homeostasis, when dysregulated it contributes to aberrant cell death in several diseases. During cellular stress BAX is transformed from an inactive cytosolic conformation to a toxic mitochondrial oligomer. Although the BAX transformation process is not well understood, drugs that interfere with this process are useful research tools and potential therapeutics. Here, we show that Eltrombopag,  an FDA-approved drug,  is a direct inhibitor of BAX. Eltrombopag binds the BAX trigger site distinctly from BAX activators, preventing them from triggering BAX conformational transformation and simultaneously promoting stabilization of the inactive BAX structure. Accordingly, Eltrombopag is capable of inhibiting BAX-mediated apoptosis induced by cytotoxic stimuli. Our data demonstrate structure-function insights into a mechanism of BAX inhibition and reveal a mechanism for Eltrombopag that may expand its use in diseases of uncontrolled cell death.

Fluorescent spherical mesoporous silica nanoparticles loaded with emodin: Synthesis, cellular uptake and anticancer activity

The natural product emodin (EO) exhibits anti-inflammatory, antiangiogenesis and antineoplastic properties in vitro and in vivo. Due to its biological properties as well as its fluorescence, EO can be useful in pharmacology and pharmacokinetics. To enhance its selectivity to cancer cells, EO was loaded into non-fluorescent and novel fluorescent spherical mesoporous nanoparticles bearing N-methyl isatoic anhydride (SNM~M) or lissamine rhodamine B sulfonyl moieties (SNM~L). The propylamine functionalized mesoporous silica nanomaterial (SNM) were characterized by powder X-ray diffraction (XRD), nitrogen gas sorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), fluorescence spectroscopy, thermogravimetric analysis (TGA) and UV spectroscopy. The cytotoxicity of EO-loaded nanoparticles was tested against the human colon carcinoma cell line HT-29. Non-loaded SNM did not affect cell proliferation, whereas those loaded with EO were at least as efficient as EO alone. It could be shown by fluorescence microscopy that the uptake of silica nanomaterial by the tumor cells occurred within 2 h and the release of EO occurred within 48 h of treatment. Flow cytometry and Western blot analysis showed that SNM containing EO induced apoptosis in HT-29 cells.

Inhibition of mitochondrial translation overcomes venetoclax resistance in AML through activation of the integrated stress response

Venetoclax is a specific B cell lymphoma 2 (BCL-2) inhibitor with promising activity against acute myeloid leukemia (AML), but its clinical efficacy as a single agent or in combination with hypomethylating agents (HMAs), such as azacitidine, is hampered by intrinsic and acquired resistance. Here, we performed a genome-wide CRISPR knockout screen and found that inactivation of genes involved in mitochondrial translation restored sensitivity to venetoclax in resistant AML cells. Pharmacologic inhibition of mitochondrial protein synthesis with antibiotics that target the ribosome, including tedizolid and doxycycline, effectively overcame venetoclax resistance. Mechanistic studies showed that both tedizolid and venetoclax suppressed mitochondrial respiration, with the latter demonstrating inhibitory activity against complex I [nicotinamide adenine dinucleotide plus hydrogen (NADH) dehydrogenase] of the electron transport chain (ETC). The drugs cooperated to activate a heightened integrated stress response (ISR), which, in turn, suppressed glycolytic capacity, resulting in adenosine triphosphate (ATP) depletion and subsequent cell death. Combination treatment with tedizolid and venetoclax was superior to either agent alone in reducing leukemic burden in mice engrafted with treatment-resistant human AML. The addition of tedizolid to azacitidine and venetoclax further enhanced the killing of resistant AML cells in vitro and in vivo. Our findings demonstrate that inhibition of mitochondrial translation is an effective approach to overcoming venetoclax resistance and provide a rationale for combining tedizolid, azacitidine, and venetoclax as a triplet therapy for AML.

Inhibition of Anti-Apoptotic Bcl-2 Proteins in Preclinical and Clinical Studies: Current Overview in Cancer

The dynamic interplay between pro-death and pro-survival Bcl-2 family proteins is responsible for a cell’s fate. Due to the recognized relevance of this family in cancer progression and response to therapy, different efforts have made in recent years in order to develop small molecules able to target anti-apoptotic proteins such as Bcl-2, Bcl-xL and Mcl-1. The limitations of the first Bcl-2 family targeted drugs, regarding on-target and off-target toxicities, have been overcome with the development of venetoclax (ABT-199), the first BH3 mimetic inhibitor approved by the FDA. The purpose of this review is to discuss the state-of-the-art in the development of drugs targeting Bcl-2 anti-apoptotic proteins and to highlight the potential of their application as single agents or in combination for improving anti-cancer therapy, focusing in particular on solid tumors.

Genotoxicity induced by hexavalent chromium leading to eryptosis in Ctenopharyngodon idellus

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