Pro-apoptotic Signaling Research Articles

Bio-mimetic strategies to re-activate apoptotic cell death for cancer treatments

Apoptosis is a crucial process to maintain the correct balance between healthy cells and committed-to-death cells in every tissue. The internal (or mitochondrial) and external (or death receptor) pathways are responsible for driving a series of molecular events that lead to apoptosis by releasing pro-apoptotic proteins, such as B-cell lymphoma-2 (BCL-2) homology 3 (BH3)-only proteins and second mitochondria-derived activator of caspases/diablo inhibitor of apoptosis protein-binding mitochondrial protein (SMAC/DIABLO), that in turn activate the caspase family of proteases. By counterbalancing the apoptogenic machinery, anti-apoptotic BCL-2 family members turn off pro-apoptotic signalling, favouring cell survival, a circumstance that is particularly pronounced in tumour cells in which apoptosis is deranged. Therefore, targeting the defective apoptotic process has become a viable therapeutic option for the treatment of several cancers and much effort is being made in the research and development of effective compounds. This review discussed and updated the most promising therapeutic strategies that target deranged apoptosis process in cancer by mimicking the pro-apoptotic effects of BH3-only and SMAC/DIABLO proteins.

NFATc4 Knockout Promotes Neuroprotection and Retinal Ganglion Cell Regeneration After Optic Nerve Injury.

Retinal ganglion cells (RGCs), neurons transmitting visual information via the optic nerve, fail to regenerate their axons after injury. The progressive loss of RGC function underlies the pathophysiology of glaucoma and other optic neuropathies, often leading to irreversible blindness. Therefore, there is an urgent need to identify the regulators of RGC survival and the regenerative program. In this study, we investigated the role of the family of transcription factors known as nuclear factor of activated T cells (NFAT), which are expressed in the retina; however, their role in RGC survival after injury is unknown. Using the optic nerve crush (ONC) model, widely employed to study optic neuropathies and central nervous system axon injury, we found that NFATc4 is specifically but transiently up-regulated in response to mechanical injury. In the injured retina, NFATc4 immunolocalized primarily to the ganglionic cell layer. Utilizing NFATc4-/- and NFATc3-/- mice, we demonstrated that NFATc4, but not NFATc3, knockout increased RGC survival, improved retina function, and delayed axonal degeneration. Microarray screening data, along with decreased immunostaining of cleaved caspase-3, revealed that NFATc4 knockout was protective against ONC-induced degeneration by suppressing pro-apoptotic signaling. Finally, we used lentiviral-mediated NFATc4 delivery to the retina of NFATc4-/- mice and reversed the pro-survival effect of NFATc4 knockout, conclusively linking the enhanced survival of injured RGCs to NFATc4-dependent mechanisms. In summary, this study is the first to demonstrate that NFATc4 knockout may confer transient RGC neuroprotection and decelerate axonal degeneration after injury, providing a potent therapeutic strategy for optic neuropathies.

Mapping of catecholaminergic denervation, neurodegeneration, and inflammation in 6-OHDA-treated Parkinson's disease mice.

Efforts to develop disease-modifying treatments for Parkinson's disease (PD) have been hindered by the lack of animal models replicating all hallmarks of PD and the insufficient attention to extra-nigrostriatal regions pathologically critical for the prodromal appearance of non-motor symptoms. Among PD models, 6-hydroxydopamine (6-OHDA) infusion in mice has gained prominence since 2012, primarily focusing on the nigrostriatal region. This study characterized widespread tyrosine hydroxylase-positive neuron and fiber loss across the brain following a unilateral 6-OHDA (20 µg) infusion into the dorsal striatum. Our analysis integrates immunolabeling, brain clearing (iDISCO+), light sheet microscopy, and computational methods, including fMRI and machine learning tools. We also examined sex differences, disease progression, neuroinflammatory responses, and pro-apoptotic signaling in nigrostriatal regions of C57BL/6 mice exposed to varying 6-OHDA dosages (5, 10, or 20 µg). This comprehensive, spatiotemporal analysis of 6-OHDA-induced pathology may guide the future design of experimental PD studies and neurotherapeutic development.

The Drosophila EcR-Hippo component Taiman promotes epithelial cell fitness by control of the Dally-like glypican and Wg gradient.

Rapidly dividing cells can eliminate slow growing neighbors through the apoptotic process of cell competition. This process ensures that only high fitness cells populate embryonic tissues and is proposed to underlie the ability of oncogene-transformed cells to progressively replace normal cells within a tissue. Patches of cells in the Drosophila wing disc overexpressing the oncogenic Taiman (Tai) transcriptional coactivator kill normal neighbors by secreting Spz ligands that trigger pro-apoptotic Toll signaling in receiving cells. However, extracellular signaling mechanisms responsible for elimination of slow growing cells by normal neighbors remain poorly defined. Here we show that slow growing cells with reduced Tai (Tai low ) are killed by normal neighbors through a mechanism involving competition for the Wingless (Wg/Wnt) ligand. Elevated Wg signaling significantly rescues elimination of Tai low cells in multiple organs, suggesting that Tai may normally promote Wg activity. Examining distribution of Wg components reveals that Tai promotes extracellular spread of the Wg ligand from source cells across the wing disc, thus ensuring patterned expression of multiple Wg-regulated target genes. Tai controls Wg spread indirectly through the extracellular glypican Dally-like protein (Dlp), which binds Wg and promotes its extracellular diffusion and capture by receptors. Data indicate that Tai likely controls Dlp at two levels: transcription of dlp mRNA and Dlp intracellular trafficking. Overall, these data indicate that the Tai acts through Dlp to enable Wg transport and signaling, and that cell competition in the Tai low model arises due to inequity in the ability of epithelial cells to sequester limiting amounts of the Wg growth factor.

Fragility of ER homeostatic regulation underlies haploid instability in human somatic cells

Mammalian somatic cells are generally unstable in the haploid state, resulting in haploid-to-diploid conversion within a short time frame. However, cellular and molecular principles that limit the sustainability of somatic haploidy remain unknown. In this study, we found the haploidy-linked vulnerability to ER stress as a critical cause of haploid intolerance in human somatic cells. Pharmacological induction of ER stress selectively induced apoptosis in haploid cells, facilitating the replacement of haploids by co-existing diploidized cells in a caspase-dependent manner. Biochemical analyses revealed that unfolded protein response (UPR) was activated with similar dynamics between haploids and diploids upon ER stress induction. However, haploids were less efficient in solving proteotoxic stress, resulting in a bias toward a proapoptotic mode of UPR signaling. Artificial replenishment of chaperone function substantially alleviated the haploidy-linked upregulation of proapoptotic signaling and improved haploid cell retention under tunicamycin-induced ER stress. These data demonstrate that the ER stress-driven haploid instability stems from inefficient proteostatic control that alters the functionality of UPR to cause apoptosis selectively in haploids. Interestingly, haploids suffered a higher level of protein aggregation even in unperturbed conditions, and the long-term stability of the haploid state was significantly improved by alleviating their natural proteotoxicity. Based on these results, we propose that the haploidy-specific vulnerability to ER stress creates a fundamental cause of haploid intolerance in mammalian somatic cells. Our findings provide new insight into the principle that places a stringent restriction on the evolution of animal life cycles.

The Mitochondrial Ubiquitin Ligase MARCHF5 Cooperates with MCL1 to Inhibit Apoptosis in KSHV-Transformed Primary Effusion Lymphoma Cell Lines.

Kaposi's sarcoma-associated herpesvirus (KSHV) causes several malignancies in people with HIV including Kaposi's sarcoma and primary effusion lymphoma (PEL). We have previously shown that PEL cell lines require myeloid cell leukemia-1 (MCL1) to inhibit apoptosis. MCL1 is an oncogene that is amplified in cancers and causes resistance to chemotherapy regimens. MCL1 is thus an attractive target for drug development. The emerging clinical relevance and therapeutic potential of MCL1 motivated us to study the roles of this oncogene in PEL in depth. Using a systems biology approach, we uncovered an unexpected genetic interaction between MCL1 and MARCHF5 indicating that they function in the same pathway. MARCHF5 is an E3 ubiquitin ligase most known for regulating mitochondrial homeostasis and antiviral signaling, but not apoptosis. We thus investigated how MCL1 and MARCHF5 cooperate to promote PEL cell survival. CRISPR knockout (KO) of MARCHF5 in PEL cell lines resulted in a significant increase in apoptosis despite the presence of MCL1. The anti-apoptotic function of MARCHF5 was dependent on its E3 ligase and dimerization activities. Loss of MARCHF5 or inhibition of the 26S proteasome furthermore stabilized the MCL1 antagonist NOXA without affecting levels of MCL1. Interestingly, NOXA KO provides a fitness advantage to PEL cells suggesting that NOXA is the pro-apoptotic signal that necessitates the anti-apoptotic activities of MCL1 and MARCHF5. Finally, endogenous reciprocal co-immunoprecipitation experiments show that MARCHF5 and NOXA are found in the same protein complex. Our findings thus provide the mechanistic link that underlies the genetic interaction between MCL1 and MARCHF5. We propose that MARCHF5 induces the degradation of the MCL1 antagonist NOXA thus reinforcing the pro-survival role of MCL1 in these tumor cells. This newly appreciated interaction of the MCL1 and MARCHF5 oncogenes may be useful to improve the design of combination therapies for KSHV malignancies.

Colon Cancer Cells Treated with Lacticaseibacillus casei Undergo Apoptosis and Release DAMPs Indicative of Immunogenic Cell Death.

Probiotic bacteria, and especially lactic acid bacteria, have long been known to wield a variety of health-beneficial effects, including antioxidant, antimicrobial, anti-inflammatory, immunomodulatory, and anticancer activities. However, our understanding of the mechanisms involved in these activities remains incomplete. In this study, we wished to investigate the processes that give rise to the anticancer activity of Lacticaseibacillus casei ATCC393 and the possibility that immunogenic cell death of cancer cells can be induced following treatment with this probiotic. In both cell lines that we have examined, we detected notable pro-apoptotic signaling, including the upregulation of death receptors, that culminated in the activation of caspase 3, the endpoint and most characteristic effector molecule of all pro-apoptotic cascades. In addition, we identified damage-associated molecular patterns associated with immunogenic cell death. Calreticulin exposure on the outer cell membrane, HMGB1 translocation outside the nucleus and depletion of intracellular ATP was evident in both cancer cell lines treated with the probiotic, while expression of type I interferons was upregulated in CT26 cells. Our findings suggest that treatment with the probiotic induced apoptosis in cancer cells, mediated by extrinsic death receptor signaling. Moreover, it resulted in the release of molecular signals related with immunogenic cell death and induction of cancer cell-specific adaptive immune responses.

Antioxidant Defenses, Oxidative Stress Responses, and Apoptosis Modulation in Spontaneous Abortion: An Immunohistochemistry Analysis of First-Trimester Chorionic Villi.

Oxidative stress (OS) and apoptosis are critical factors in placental development and function. Their interplay influences trophoblast proliferation, differentiation, and invasion, as well as vascular development. An imbalance between these processes can lead to pregnancy-related disorders such as preeclampsia, intrauterine growth restriction, and even spontaneous abortion. Our study seeks to elucidate the associations between preventive antioxidant/protective OS response factors-glutathione (GSH), MutT Homolog 1 (MTH1), and apoptotic regulation modulators-tumor protein p53 and B-cell lymphoma (Bcl-2) transcripts, in the context of spontaneous abortion (30 samples) versus elective termination of pregnancy (20 samples), using immunohistochemistry (IHC) to determine their proteomic expression in chorionic villi within abortive fetal placenta tissue samples. Herein, comparative statistical analyses revealed that both OS response factors, GSH and MTH1, were significantly under-expressed in spontaneous abortion cases as compared to elective. Conversely, for apoptotic regulators, p53 expression was significantly higher in spontaneous abortion cases, whereas Bcl-2 expression was significantly lower in spontaneous abortion cases. These findings suggest that a strong pro-apoptotic signal is prevalent within spontaneous abortion samples, alongside reduced anti-apoptotic protection, depleted antioxidant defenses and compromised oxidative DNA damage prevention/repair, as compared to elective abortion controls. Herein, our hypothesis that OS and apoptosis are closely linked processes contributing to placental dysfunction and spontaneous abortion was thus seemingly corroborated. Our results further highlight the importance of maintaining redox homeostasis and apoptotic regulation for a successful pregnancy. Understanding the mechanisms underlying this interplay is essential for developing potential therapies to manage OS, promote placentation, and avoid unwanted apoptosis, ultimately improving pregnancy outcomes. Antioxidant supplementation, modulation of p53 activity, and the enhancement of DNA repair mechanisms may represent potential approaches to mitigate OS and apoptosis in the placenta. Further research is needed to explore these strategies and their efficacy in preventing spontaneous abortion.

Ixeris polycephala Extract Alleviates Progression of Benign Prostatic Hyperplasia via Modification of Proliferation, Apoptosis, and Inflammation.

Benign prostatic hyperplasia (BPH) is a urogenital disorder that is common in aging men. Ixeris polycephala (IP) is used in traditional medicine and contains pharmacologically active compounds. However, the effect for BPH progression has not been elucidated. We herein examined the protective potential of IP extract on a testosterone-induced model of BPH in rats. To generate the BPH model, daily subcutaneous administration of testosterone was applied for 4 weeks. During this period, the rats were also administered a daily oral gavage of IP (150 mg/kg), finasteride (positive control), or vehicle. Testosterone treatment was associated with a significantly higher prostate-to-body weight ratio, serum dihydrotestosterone (DHT) level, and prostatic gene expression of 5α-reductase compared to untreated controls. Notably, IP plus testosterone co-treatment was associated with decreased epithelial thickness, down-regulation of proliferating cell nuclear antigen (PCNA) and cyclin D1, and upregulation of pro-apoptotic signaling molecules. IP co-treatment also down-regulated pro-inflammatory cytokines, cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) and decreased inflammatory cell infiltration compared to the levels seen in the testosterone-induced BPH. IP appears to protect rats against the progression of testosterone-induced BPH by alleviating prostate cell growth and inflammatory responses, and thus may have potential for clinical use against BPH progression.

METTL14-Mediated Bim mRNA m6A Modification Augments Osimertinib Sensitivity in EGFR-Mutant NSCLC Cells.

Resistance to osimertinib represents a significant challenge for the successful treatment of non-small cell lung cancer (NSCLC) harboring activating mutations in EGFR. N6-methyladenosine (m6A) on mRNAs is critical for various biological processes, yet whether m6A regulates osimertinib resistance of NSCLC remains unknown. In this study, we demonstrated that developing osimertinib-resistant phenotypes depends on m6A reduction resulting from downexpression of m6A methyltransferase METTL14 in EGFR-mutant NSCLCs. Both in vitro and in vivo assays showed that specific knockdown of METTL14 was sufficient to confer osimertinib resistance and that elevated expression of METTL14 rescued the efficacy of osimertinib in the resistant NSCLC cells. Mechanistically, METTL14 promoted m6A methylation of pro-apoptotic Bim mRNA and increased Bim mRNA stability and expression, resulting in activating the Bim-dependent pro-apoptotic signaling and thereby promoting osimertinib-induced cell apoptosis. Analysis of clinical samples revealed that decreased expression of METTL14 was observed in osimertinib-resistant NSCLC tissues and significantly associated with a poor prognosis. In conclusion, our study reveals a novel regulatory mechanism by which METTL14-mediated m6A methylation of Bim mRNA inhibited osimertinib resistance of NSCLC cells. It offers more evidences for the involvement of m6A modification in regulation of osimertinib resistance and provides potential therapeutic targets for novel approaches to overcome the tolerance of osimertinib and other EGFR tyrosine kinase inhibitors. Implications: This study offers more evidences for the involvement of METTL14-mediated N6-methyladenosine modification in regulation of osimertinib resistance and provides potential therapeutic targets for novel approaches to overcome the tolerance of osimertinib and other EGFR tyrosine kinase inhibitors.

Cleavage of protein kinase c δ by caspase-3 mediates proinflammatory cytokine-induced apoptosis in pancreatic islets

In type 1 diabetes (T1D), autoreactive immune cells infiltrate the pancreas and secrete pro-inflammatory cytokines that initiate cell death in insulin producing islet β-cells. Protein kinase C δ (PKCδ) plays a role in mediating cytokine-induced β-cell death; however, the exact mechanisms are not well understood. To address this, we utilized an inducible β-cell specific PKCδ KO mouse as well as a small peptide inhibitor of PKCδ. We identified a role for PKCδ in mediating cytokine-induced β-cell death and have shown that inhibiting PKCδ protects pancreatic β-cells from cytokine-induced apoptosis in both mouse and human islets. We determined that cytokines induced nuclear translocation and activity of PKCδ and that caspase-3 cleavage of PKCδ may be required for cytokine-mediated islet apoptosis. Further, cytokine activated PKCδ increases activity both of pro-apoptotic Bax with acute treatment and JNK with prolonged treatment. Overall, our results suggest that PKCδ mediates cytokine-induced apoptosis via nuclear translocation, cleavage by caspase-3, and upregulation of pro-apoptotic signaling in pancreatic β-cells. Combined with the protective effects of PKCδ inhibition with δV1-1, the results of this study will aid in the development of novel therapies to prevent or delay β-cell death and preserve β-cell function in T1D.

Blood Brain Barrier-Crossing Delivery of Felodipine Nanodrug Ameliorates Anxiety-Like Behavior and Cognitive Impairment in Alzheimer's Disease.

Alzheimer's disease (AD) is the most common age-related neurodegenerative disorder leading to cognitive decline. Excessive cytosolic calcium (Ca2+) accumulation plays a critical role in the pathogenesis of AD since it activates the NOD-like receptor family, pyrin domain containing 3 (NLRP3), switches the endoplasmic reticulum (ER) unfolded protein response (UPR) toward proapoptotic signaling and promotes Aβ seeding. Herein, a liposomal nanodrug (felodipine@LND) is developed incorporating a calcium channel antagonist felodipine for Alzheimer's disease treatment through a low-intensity pulse ultrasound (LIPUS) irradiation-assisted blood brain barrier (BBB)-crossing drug delivery. The multifunctional felodipine@LND is effectively delivered to diseased brain through applying a LIPUS irradiation to the skull, which resulted in a series of positive effects against AD. Markedly, the nanodrug treatment switched the ER UPR toward antioxidant signaling, prevented the surface translocation of ER calreticulin (CALR) in microglia, and inhibited the NLRP3 activation and Aβ seeding. In addition, it promoted the degradation of damaged mitochondria via mitophagy, thereby inhibiting the neuronal apoptosis. Therefore, the anxiety-like behavior and cognitive impairment of 5xFAD mice with AD is significantly ameliorated, which manifested the potential of LIPUS - assisted BBB-crossing delivery of felodipine@LND to serve as a paradigm for AD therapy based on the well-recognized clinically available felodipine.

Mechanisms of Cancerprotective Effects of Phytosterols. Literature Review

Cancer is recognized as the second leading cause of mortality in the Russian Federation. Prolonging the life of oncology patients involves treatment with toxic drugs, causing multiple side effects. Today, scientists around the world are striving to find non-toxic drugs. The present study explores phytosterols. Phytosterols refer to a class of steroids widely distributed in plants as an essential component of plant cell membranes. They include stigmasterol, beta-sitosterol, and campesterol. Stigmasterol has been found to increase the expression of proapoptotic genes (Bax, p53) and decrease the expression of the antiapoptotic gene Bcl-2 in HepG2 liver cancer cells. Stigmasterol is able to induce cell arrest in G0-G1 phase (stationary phase), resulting in fewer cells in the G2/M phase (division phase). It induces apoptosis and protective autophagy in gastric cancer cells while inhibiting the Akt/mTOR signaling pathway. β-sitosterol exhibits growth inhibitory and cytotoxic effects against a number of established cancer cell lines in vitro and in vivo, and remains free from acute/subacute toxic effects. β-sitosterol is widely used to treat chronic prostate diseases. In 2020, spendings on dietary supplements rich in beta-sitosterol accounted for $24 827 065 in the USA. Campesterol induces cell apoptosis via the mitochondrial pathway. It appears cytotoxic to U937 hepatocellular cancer cells. Campesterol induces cell apoptosis and activates proapoptotic signaling in ovarian cancer cell lines of a person. The present literature review demonstrates that specific substances in this group, beta-sitosterol, stigmasterol, and campesterol, provide pronounced antitumor effects.

Downregulation of Protease Cathepsin D and Upregulation of Pathologic α-Synuclein Mediate Paucity of DNAJC6-Induced Degeneration of Dopaminergic Neurons.

A homozygous mutation of the DNAJC6 gene causes autosomal recessive familial type 19 of Parkinson's disease (PARK19). To test the hypothesis that PARK19 DNAJC6 mutations induce the neurodegeneration of dopaminergic cells by reducing the protein expression of functional DNAJC6 and causing DNAJC6 paucity, an in vitro PARK19 model was constructed by using shRNA-mediated gene silencing of endogenous DANJC6 in differentiated human SH-SY5Y dopaminergic neurons. shRNA targeting DNAJC6 induced the neurodegeneration of dopaminergic cells. DNAJC6 paucity reduced the level of cytosolic clathrin heavy chain and the number of lysosomes in dopaminergic neurons. A DNAJC6 paucity-induced reduction in the lysosomal number downregulated the protein level of lysosomal protease cathepsin D and impaired macroautophagy, resulting in the upregulation of pathologic α-synuclein or phospho-α-synucleinSer129 in the endoplasmic reticulum (ER) and mitochondria. The expression of α-synuclein shRNA or cathepsin D blocked the DNAJC6 deficiency-evoked degeneration of dopaminergic cells. An increase in ER α-synuclein or phospho-α-synucleinSer129 caused by DNAJC6 paucity activated ER stress, the unfolded protein response and ER stress-triggered apoptotic signaling. The lack of DNAJC6-induced upregulation of mitochondrial α-synuclein depolarized the mitochondrial membrane potential and elevated the mitochondrial level of superoxide. The DNAJC6 paucity-evoked ER stress-related apoptotic cascade, mitochondrial malfunction and oxidative stress induced the degeneration of dopaminergic neurons via activating mitochondrial pro-apoptotic signaling. In contrast with the neuroprotective function of WT DNAJC6, the PARK19 DNAJC6 mutants (Q789X or R927G) failed to attenuate the tunicamycin- or rotenone-induced upregulation of pathologic α-synuclein and stimulation of apoptotic signaling. Our data suggest that PARK19 mutation-induced DNAJC6 paucity causes the degeneration of dopaminergic neurons via downregulating protease cathepsin D and upregulating neurotoxic α-synuclein. Our results also indicate that PARK19 mutation (Q789X or R927G) impairs the DNAJC6-mediated neuroprotective function.

Loss of the lysosomal protein CLN3 modifies the lipid content of the nuclear envelope leading to DNA damage and activation of YAP1 pro-apoptotic signaling.

Batten disease is characterized by early-onset blindness, juvenile dementia and death during the second decade of life. The most common genetic causes are mutations in the CLN3 gene encoding a lysosomal protein. There are currently no therapies targeting the progression of the disease, mostly due to the lack of knowledge about the disease mechanisms. To gain insight into the impact of CLN3 loss on cellular signaling and organelle function, we generated CLN3 knock-out cells in a human cell line (CLN3-KO), and performed RNA sequencing to obtain the cellular transcriptome. Following a multi-dimensional transcriptome analysis, we identified the transcriptional regulator YAP1 as a major driver of the transcriptional changes observed in CLN3-KO cells. We further observed that YAP1 pro-apoptotic signaling is hyperactive as a consequence of CLN3 functional loss in retinal pigment epithelia cells, and in the hippocampus and thalamus of CLN3exΔ7/8 mice, an established model of Batten disease. Loss of CLN3 activates YAP1 by a cascade of events that starts with the inability of releasing glycerophosphodiesthers from CLN3-KO lysosomes, which leads to perturbations in the lipid content of the nuclear envelope and nuclear dysmorphism. This results in increased number of DNA lesions, activating the kinase c-Abl, which phosphorylates YAP1, stimulating its pro-apoptotic signaling. Altogether, our results highlight a novel organelle crosstalk paradigm in which lysosomal metabolites regulate nuclear envelope content, nuclear shape and DNA homeostasis. This novel molecular mechanism underlying the loss of CLN3 in mammalian cells and tissues may open new c-Abl-centric therapeutic strategies to target Batten disease.

PTPRO inhibits LPS-induced apoptosis in alveolar epithelial cells

Acute lung injury (ALI) and its severe manifestation, acute respiratory distress syndrome (ARDS), represent critical clinical syndromes with multifactorial origins, notably stemming from sepsis within intensive care units (ICUs). Despite their high mortality rates, no selective cure is available beside ventilation support. Apoptosis plays a complex and pivotal role in the pathophysiology of acute lung injury. Excessive apoptosis of alveolar epithelial and microvascular endothelial cells can lead to disruption of lung epithelial barrier integrity, impairing the body's ability to exchange blood and gas. At the same time, apoptosis of damaged or dysfunctional cells, including endothelial and epithelial cells, can help maintain tissue integrity and accelerate recovery from organ pro-inflammatory stress. The balance between pro-survival and pro-apoptotic signals in lung injury determines patient outcomes, making the modulation of apoptosis an area of intense research in the quest for more effective therapies. Here we found that protein tyrosine phosphatase receptor type O (PTPRO), a poorly understood receptor-like protein tyrosine phosphatase, is consistently upregulated in multiple tissue types of mice under septic conditions and in the lung alveolar epithelial cells. PTPRO reduction by its selective short-interfering RNA (siRNA) leads to excessive apoptosis in lung alveolar epithelial cells without affecting cell proliferation. Consistently PTPRO overexpression by a DNA construct attenuates apoptotic signaling induced by LPS. These effects of PTPTO on cellular apoptosis are dependent on an ErbB2/PI3K/Akt/NFκB signaling pathway. Here we revealed a novel regulatory pathway of cellular apoptosis by PTPRO in lung alveolar epithelial cells during sepsis.

Advantages and disadvantages of mitochondrial mechanism (mitophagy) for cancer treatment

Mitochondrial organelles are crucial organelles for the energy supply of the whole cell. Also, mitochondria are beneficial for the production of ATP, a byproduct of the stabilization of nutrients in the TCA cycle, and FADH and NADH are reducing equivalents. Defects in mitochondria impair the energy supply, metabolite production, and redox reactions. Also, a crucial point for cell survival is to maintain mitochondrial quality rather than quantity. Qualitative mitochondria are required to produce the proper amount of ATP, degrade p53, and decrease reactive oxygen species (ROS) production. All of these factors lead to mitochondrial dysfunction. Dysfunctional mitochondria are „eaten“ by autophagosomes through the process of mitophagy. Mitophagy is crucial since it prevents the build-up of poorly/affected mitochondria, and prevents excess production of ROS and mtDNA mutation. Also, mitophagy shows positive effects on cancer, since mitophagy promotes pro-apoptotic signals for cancer stem cells (CSC). Due to all the advantages of mitophagy, this organelle can be used as a beneficial assistant for chemotherapy in cancer treatment. The authors of these papers provide a pathway for using mitophagy combined with cancer treatment. This claim is confirmed within the paper, with tables provided. Our results show the importance of mitophagy in human organisms and its importance in cancer.

Abstract 4752: Enhancer of zeste homolog 2 inhibitors overcome glucocorticoid resistance in acute lymphoblastic leukemia by augmenting pro-apoptotic signaling

Abstract Introduction Relapsed acute lymphoblastic leukemia (ALL) portends a poor prognosis. Glucocorticoids (GCs) are a central component of a multi-agent regimen to treat ALL. GCs mediate ligand-dependent global transcriptional changes activating feedback loop that increases GC receptor (GR) expression and pro-apoptotic signaling. GC resistance is a common mechanism in relapsed/refractory ALL. Altered function of Enhancer of Zeste Homolog 2 (EZH2), a histone methyl transferase (HMT), including increased expression and activating mutations have been reported in ALL. Previously, EZH2 inhibitors have been shown to increase GC efficacy in non-ALL B-cell lymphoid malignancies including non-Hodgkin lymphoma. Furthermore, EZH2 inhibitors reversed GC resistance and increased efficacy of GCs in an ALL subtype with an activating point mutation in an HMT called nuclear set domain 2. Overcoming GC resistance by novel therapeutic strategies may help improve outcomes in relapsed/refractory ALL. Hypothesis EZH2 inhibitors may enhance GC efficacy by augmenting downstream effects of GCs. Methods We performed in-vitro studies of EZH2 inhibitors, EPZ-6438 and CPI-1205, at graded doses in GC resistance human-derived B-cell (SUPB15) and T-cell (SUPT1, KOPTK1, PEER) ALL cell lines followed by graded doses of dexamethasone (dex). Cell viability was performed using CellTiter-Glo assay. Induction of apoptosis was measured with Annexin V flow cytometry. Pro-apoptotic BIM mRNA and protein levels were measured using real-time PCR and immunoblot. Global H3K27me3 protein levels were assessed using immunoblot. Results GC resistant B-cell ALL and T-cell ALL treated with EZH2 inhibitors for 3-7 days followed by the addition of dex for 48-72 hours led to decreased cell viability and increased apoptosis of the ALL cells compared to cells treated with vehicle (DMSO) and dex alone. EZH2 inhibitors on their own did not cause apoptosis. SynergyFinder revealed Bliss synergy scores between 23- 31 in B-cell ALL and T-cell ALL cell lines with greater than 10 considered a synergistic drug interaction. Immunoblotting of cells treated with EZH2 inhibitors alone showed an increase in pro-apoptotic protein, BIM. BIM level was further enhanced when dex was added in combination with EZH2 inhibitors compared to vehicle and dex alone suggesting that EZH2 inhibitors were augmenting BIM expression. Further assessment of the mechanism of how EZH2 inhibitors lead to improved GC efficacy will be performed by integrating transcriptomic and epigenomic profiling in the presence and absence of EZH2 inhibitors. Furthermore, in-vivo testing of EZH2 inhibitors in patient derived xenografts will be performed. Conclusion EZH2 inhibitors can overcome GC resistance in ALL posing as a potential novel therapeutic agent to treat relapsed/refractory ALL. Citation Format: Mansi Dalal, Joanna Yi, Jianping Li, Amin Shobh, Daphne DupereRicher, Richard Bennett, Jonathan Licht. Enhancer of zeste homolog 2 inhibitors overcome glucocorticoid resistance in acute lymphoblastic leukemia by augmenting pro-apoptotic signaling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4752.

Molecular Adaptation of Cardiac Remodeling in Metabolic Syndrome: Focus on AMPK, SIRT1 and PGC-1a

Obesity, lack of physical activity, and genetic predisposition might play a pivotal role in pathogenesis of metabolic syndrome. Cardiac function alteration including hemodynamic changes, contractility function, arrhythmia, and cellular respiratory function, might happen due to chronic condition in metabolic syndrome. Insulin resistance, neurohormonal activation and chronic inflammation might contribute to these changes. Cardiomyocyte had capabilities to adapt from these abnormalities, one of them is the activation of cellular pathway to resist cardiac injury from metabolic syndrome. This molecular pathway involves three proteins, including AMP-activated protein kinase (AMPK), sirtuin-1 (SIRT1) and peroxisome proliferator-activated receptor γ coactivator-α (PGC-1α). The aim of this narrative review is to elucidate role of AMPK, SIRT1, and PGC-1α in cardiac adaptation against cardiac dysfunction in metabolic syndrome. AMPK, SIRT-1, and PGC-1α contribute to adapt and to repair the cardiac injury resulting from celullar and mechanical stress from metabolic syndrome and prevent cardiac remodeling event. Several pathological events, such as insulin resistance, induce alteration of switching energy fuel to the heart, causing cardiomyocte to rely on glucose metabolism and lipotoxicity, leading to damages of cardiomyocyte through reactive oxygen species (ROS) generation and lipid peroxidation. Increase of ROS promotes cardiac injury followed by necrotic and apoptotic events. AMPK, SIRT1, and PGC-1α act as cardioprotector molecule against metabolic syndrome insults to several mechanism such as: AMPK play role as counter act of lipotoxicity and insulin resistance through increasing insulin sensitivity and regulate redox reaction. SIRT1 plays role in regulating apoptotic genes and PGC-1α repairs cardiac fuel sources. Activation of AMPK/SIRT1/PGC-1α prevent cardiac remodeling due to metabolic syndrome by increasing insulin sensitivity, increases mitochondrial biogenesis and reduce pro-apoptotic signals in cardiomyocte.Keywords: AMPK/SIRT1/PGC-α, cardiac remodeling, metabolic syndrome

TNF-Related Apoptosis-Inducing Ligand: Non-Apoptotic Signalling.

TNF-related apoptosis-inducing ligand (TRAIL or Apo2 or TNFSF10) belongs to the TNF superfamily. When bound to its agonistic receptors, TRAIL can induce apoptosis in tumour cells, while sparing healthy cells. Over the last three decades, this tumour selectivity has prompted many studies aiming at evaluating the anti-tumoral potential of TRAIL or its derivatives. Although most of these attempts have failed, so far, novel formulations are still being evaluated. However, emerging evidence indicates that TRAIL can also trigger a non-canonical signal transduction pathway that is likely to be detrimental for its use in oncology. Likewise, an increasing number of studies suggest that in some circumstances TRAIL can induce, via Death receptor 5 (DR5), tumour cell motility, potentially leading to and contributing to tumour metastasis. While the pro-apoptotic signal transduction machinery of TRAIL is well known from a mechanistic point of view, that of the non-canonical pathway is less understood. In this study, we the current state of knowledge of TRAIL non-canonical signalling.