X-linked Inhibitor Of Apoptosis Protein Research Articles

Interplay of p53 and XIAP protein dynamics orchestrates cell fate in response to chemotherapy

Chemotherapeutic drugs are used to treat almost all types of cancer, but the intended response, i.e., elimination, is often incomplete, with a subset of cancer cells resisting treatment. Two critical factors play a role in chemoresistance: the p53 tumour suppressor gene and the X-linked inhibitor of apoptosis (XIAP). These proteins have been shown to act synergistically to elicit cellular responses upon DNA damage induced by chemotherapy, yet, the mechanism is poorly understood. This study introduces a mathematical model characterising the apoptosis pathway activation by p53 before and after mitochondrial outer membrane permeabilisation upon treatment with the chemotherapy Doxorubicin (Dox). “In-silico” simulations show that the p53 dynamics change dose-dependently. Under medium to high doses of Dox, p53 concentration ultimately stabilises to a high level regardless of XIAP concentrations. However, caspase-3 activation may be triggered or not depending on the XIAP induction rate, ultimately determining whether the cell will perish or resist. Consequently, the model predicts that failure to activate apoptosis in some cancer cells expressing wild-type p53 might be due to heterogeneity between cells in upregulating the XIAP protein, rather than due to the p53 protein concentration. Our model suggests that the interplay of the p53 dynamics and the XIAP induction rate is critical to determine the cancer cells’ therapeutic response.

Disruption of zinc (II) binding and dimeric protein structure of the XIAP-RING domain by copper (I) ions.

Modulation of metalloprotein structure and function via metal ion substitution may constitute a molecular basis for metal ion toxicity and/or metal-mediated functional control. The X-linked Inhibitor of Apoptosis Protein (XIAP) is a metalloprotein that requires zinc for proper structure and function. In addition to its role as a modulator of apoptosis, XIAP has been implicated in copper homeostasis. Given the similar coordination preferences of copper and zinc, investigation of XIAP structure and function upon interaction with copper is relevant. The Really Interesting New Gene (RING) domain of XIAP is representative of a class of zinc finger proteins that utilize a bi-nuclear zinc-binding motif to maintain proper structure and ubiquitin ligase function. Herein, we report the characterization of copper (I) binding to the Zn2-RING domain of XIAP. Electronic absorption studies that monitor copper-thiolate interactions demonstrate that the RING domain of XIAP binds 5-6 Cu(I) ions and that copper is thermodynamically preferred relative to zinc. Repetition of the experiments in the presence of the Zn(II)-specific dye Mag-Fura2 shows that Cu(I) addition results in Zn(II) ejection from the protein, even in the presence of glutathione. Loss of dimeric structure of the RING domain, which is a requirement for its ubiquitin ligase activity, upon copper substitution at the zinc-binding sites, was readily observed via size exclusion chromatography. These results provide a molecular basis for the modulation of RING function by copper and add to the growing body of literature that describe the impact of Cu(I) on zinc metalloprotein structure and function.

X-linked inhibitor of apoptosis protein (XIAP) expression level analyzed by immunohistochemistry (IHC) as it relates to clinical and pathologic characteristics in prostate cancer.

e17012 Background: XIAP acts in both the extrinsic and intrinsic apoptotic pathways as an inhibitor of cell death, protecting cells from a range of triggers. Regulation due to apoptosis resistance may represent a targetable factor for therapeutic intervention in prostate cancer. This study focuses on XIAP as a biomarker and its expression in correlation with disease aggression. Methods: Expression levels of XIAP was analyzed by immunohistochemistry (IHC), graded 1 through 3 according to signal intensity, in radical prostatectomy samples from 90 patients with prostate cancer with a range of phenotypes including: indolent (A), locally advanced (B), progressive to metastatic (C) and de novo metastatic (D). Prognostic data was collected and Fisher’s exact statistical analysis was performed. Secondary analyses included a Fisher’s exact test with a pairwise comparison between individual disease grades and Gleason scores. Results: Higher XIAP protein expression levels on IHC correlated with disease grade and with total Gleason score (p = 0.0008 and p = 0.0002 respectively) by Fisher’s exact test analysis, indicating more aggressive disease phenotypes. Secondary results looked at a pairwise Fisher’s exact analysis comparing XIAP expression levels among disease grades (A-D) and Gleason scores. XIAP expression only significantly differed between those with grade A and D as well as between individuals with grades B and D (measured by Bonferroni-adjusted p-value of 0.003 and 0.018 respectively). Statistical significance was also achieved in XIAP expression levels when comparing among Gleason scores 6 and 8 (p = 0.025), 6 and 9 (p = 0.0125), as well as 7 and 9 (p = 0.030). Conclusions: This study demonstrates a correlation between XIAP expression levels by IHC and aggressiveness of disease, demonstrating clinical significance of XIAP as a prostate cancer biomarker. [Table: see text]

Characterization of a Potent and Orally Bioavailable Lys-Covalent Inhibitor of Apoptosis Protein (IAP) Antagonist.

We have recently reported on the use of aryl-fluorosulfates in designing water- and plasma-stable agents that covalently target Lys, Tyr, or His residues in the BIR3 domain of the inhibitor of the apoptosis protein (IAP) family. Here, we report further structural, cellular, and pharmacological characterizations of this agent, including the high-resolution structure of the complex between the Lys-covalent agent and its target, the BIR3 domain of X-linked IAP (XIAP). We also compared the cellular efficacy of the agent in two-dimensional (2D) and three-dimensional (3D) cell cultures, side by side with the clinical candidate reversible IAP inhibitor LCL161. Finally, in vivo pharmacokinetic studies indicated that the agent was long-lived and orally bioavailable. Collectively our data further corroborate that aryl-fluorosulfates, when incorporated correctly in a ligand, can result in Lys-covalent agents with pharmacodynamic and pharmacokinetic properties that warrant their use in the design of pharmacological probes or even therapeutics.

Combined inhibition of XIAP and autophagy induces apoptosis and differentiation in acute myeloid leukaemia.

Perturbations in autophagy, apoptosis and differentiation have greatly affected the progression and therapy of acute myeloid leukaemia (AML). The role of X-linked inhibitor of apoptosis (XIAP)-related autophagy remains unclear in AML therapeutics. Here, we found that XIAP was highly expressed and associated with poor overall survival in patients with AML. Furthermore, pharmacologic inhibition of XIAP using birinapant or XIAP knockdown via siRNA impaired the proliferation and clonogenic capacity by inducing autophagy and apoptosis in AML cells. Intriguingly, birinapant-induced cell death was aggravated in combination with ATG5 siRNA or an autophagy inhibitor spautin-1, suggesting that autophagy may be a pro-survival signalling. Spautin-1 further enhanced the ROS level and myeloid differentiation in THP-1 cells treated with birinapant. The mechanism analysis showed that XIAP interacted with MDM2 and p53, and XIAP inhibition notably downregulated p53, substantially increased the AMPKα1 phosphorylation and downregulated the mTOR phosphorylation. Combined treatment using birinapant and chloroquine significantly retarded AML progression in both a subcutaneous xenograft model injected with HEL cells and an orthotopic xenograft model injected intravenously with C1498 cells. Collectively, our data suggested that XIAP inhibition can induce autophagy, apoptosis and differentiation, and combined inhibition of XIAP and autophagy may be a promising therapeutic strategy for AML.

MicroRNA-381 Enhances Radiosensitivity in Esophageal Squamous Cell Carcinoma by Targeting X-Linked Inhibitor of Apoptosis Protein [Retraction

[This retracts the article DOI: 10.2147/OTT.S134551.].

Synthesis and biological evaluation of dual MDM2/XIAP inhibitors based on the tetrahydroquinoline scaffold

Overexpression of both human murine double minute 2 (MDM2) and X-linked inhibitor of apoptosis protein (XIAP) is detected in tumor cells from several cancer types, including childhood acute leukemia lymphoma (ALL), neuroblastoma (NB), and prostate cancer, and is associated with disease progression and treatment resistance. In this report, we described the design and syntheses of a series of dual MDM2/XIAP inhibitors based on the tetrahydroquinoline scaffold from our previously reported lead compound JW-2-107 and tested their cytotoxicity in a panel of human cancer cell lines. The best compound identified in this study is compound 3e. Western blot analyses demonstrated that treatments with 3e decreased MDM2 and XIAP protein levels and increased expression of p53, resulting in cancer cell growth inhibition and cell death. Furthermore, compound 3e effectively inhibited tumor growth in vivo when tested using a human 22Rv1 prostate cancer xenograft model. Collectively, results in this study strongly suggest that the tetrahydroquinoline scaffold, represented by 3e and our earlier lead compound JW-2-107, has abilities to dual target MDM2 and XIAP and is promising for further preclinical development.

Involvement and targeted intervention of benzo(a)pyrene-regulated apoptosis related proteome modification and muti-drug resistance in hepatocellular carcinoma

During the development of hepatocellular carcinoma (HCC), the mutual adaptation and interaction of HCC cells and the microenvironment play an important role. Benzo(a)pyrene (B[a]P) is a common environmental pollutant, which can induce the initiation of various malignant tumors, including HCC. However, the effects of B[a]P exposure on progression of HCC and the potential mechanisms remains largely uninvestigated. Here we found that, after the long-term exposure of HCC cells to low dose of B[a]P, it activated glucose-regulated protein 75 (GRP75), which then induced a modification of apoptosis-related proteome. Among them, we identified the X-linked inhibitor of apoptosis protein (XIAP) as a key downstream factor. XIAP further blocked the caspase cascade activation and promoted the acquisition of the anti-apoptosis abilities, ultimately leading to multi-drug resistance (MDR) in HCC. Furthermore, the abovementioned effects were markedly attenuated when we inhibited GRP75 by using 3,4-dihydroxycinnamic acid (caffeic acid, CaA). Collectively, our present study revealed the effects of B[a]P exposure on the progression of HCC, and identified GRP75 was a meaningful factor involved in.

Lead exposure disturbs ATP7B-mediated copper export from brain barrier cells by inhibiting XIAP-regulated COMMD1 protein degradation

The brain barrier is an important structure for metal ion homeostasis. According to studies, lead (Pb) exposure disrupts the transportation of copper (Cu) through the brain barrier, which may cause impairment of the nervous system; however, the specific mechanism is unknown. The previous studies suggested the X-linked inhibitor of apoptosis (XIAP) is a sensor for cellular Cu level which mediate the degradation of the MURR1 domain-containing 1 (COMMD1) protein. XIAP/COMMD1 axis was thought to be an important regulator in Cu metabolism maintenance. In this study, the role of XIAP-regulated COMMD1 protein degradation in Pb-induced Cu disorders in brain barrier cells was investigated. Pb exposure significantly increased Cu levels in both cell types, according to atomic absorption technology testing. Western blotting and reverse transcription PCR (RT-PCR) showed that COMMD1 protein levels were significantly increased, whereas XIAP, ATP7A, and ATP7B protein levels were significantly decreased. However, there were no significant effects at the messenger RNA (mRNA) level (XIAP, ATP7A, and ATP7B). Pb-induced Cu accumulation and ATP7B expression were reduced when COMMD1 was knocked down by transient small interfering RNA (siRNA) transfection. In addition, transient plasmid transfection of XIAP before Pb exposure reduced Pb-induced Cu accumulation, increased COMMD1 protein levels, and decreased ATP7B levels. In conclusion, Pb exposure can reduce XIAP protein expression, increase COMMD1 protein levels, and specifically decrease ATP7B protein levels, resulting in Cu accumulation in brain barrier cells.

In Silico Exploration of Metabolically Active Peptides as Potential Therapeutic Agents against Amyotrophic Lateral Sclerosis.

Amyotrophic lateral sclerosis (ALS) is regarded as a fatal neurodegenerative disease that is featured by progressive damage of the upper and lower motor neurons. To date, over 45 genes have been found to be connected with ALS pathology. The aim of this work was to computationally identify unique sets of protein hydrolysate peptides that could serve as therapeutic agents against ALS. Computational methods which include target prediction, protein-protein interaction, and peptide-protein molecular docking were used. The results showed that the network of critical ALS-associated genes consists of ATG16L2, SCFD1, VAC15, VEGFA, KEAP1, KIF5A, FIG4, TUBA4A, SIGMAR1, SETX, ANXA11, HNRNPL, NEK1, C9orf72, VCP, RPSA, ATP5B, and SOD1 together with predicted kinases such as AKT1, CDK4, DNAPK, MAPK14, and ERK2 in addition to transcription factors such as MYC, RELA, ZMIZ1, EGR1, TRIM28, and FOXA2. The identified molecular targets of the peptides that support multi-metabolic components in ALS pathogenesis include cyclooxygenase-2, angiotensin I-converting enzyme, dipeptidyl peptidase IV, X-linked inhibitor of apoptosis protein 3, and endothelin receptor ET-A. Overall, the results showed that AGL, APL, AVK, IIW, PVI, and VAY peptides are promising candidates for further study. Future work would be needed to validate the therapeutic properties of these hydrolysate peptides by in vitro and in vivo approaches.

Downstream of kinase 3 promotes proliferation and inhibits apoptosis of prostate cancer via the NF-κB signaling pathway.

Downstream of kinase 3 (DOK3) is involved primarily with immune cell infiltration. Recent research reported the role of DOK3 in tumor progression, with opposite effects in lung cancer and gliomas; however, its role in prostate cancer (PCa) remains elusive. This study aimed to explore the role of DOK3 in PCa and to determine the mechanisms involved. To investigate the functions and mechanisms of DOK3 in PCa, we performed bioinformatic and biofunctional analyses. Samples from patients with PCa were collected from West China Hospital, and 46 were selected for the final correlation analysis. A lentivirus-based short hairpin ribonucleic acid (shRNA) carrier was established for silencing DOK3. A series of experiments involving the cell counting kit-8, bromodeoxyuridine, and flow cytometry assays were performed to identify cell proliferation and apoptosis. Changes in biomarkers from the nuclear factor kappa B (NF-κB) signaling pathway were detected to verify the relationship between DOK3 and the NF-κB pathway. A subcutaneous xenograft mouse model was performed to examine phenotypes after knocking down DOK3 in vivo. Rescue experiments with DOK3 knockdown and NF-κB pathway activation were designed to verify regulating effects. DOK3 was up-regulated in PCa cell lines and tissues. In addition, a high level of DOK3 was predictive of higher pathological stages and worse prognoses. Similar results were observed with PCa patient samples. After silencing DOK3 in PCa cell lines 22RV1 and PC3, cell proliferation was significantly inhibited while apoptosis was promoted. Gene set enrichment analysis revealed that DOK3 function was enriched in the NF-κB pathway. Mechanism experiments determined that knockdown of DOK3 suppressed activation of the NF-κB pathway, increased the expressions of B-cell lymphoma-2 like 11 (BIM) and B-cell lymphoma-2 associated X (BAX), and decreased the expression of phosphorylated-P65 and X-linked inhibitor of apoptosis (XIAP). In the rescue experiments, pharmacological activation of NF-κB by tumor necrosis factor-α (TNF-α) partially recovered cell proliferation after the knockdown of DOK3. Our findings suggest that overexpression of DOK3 promotes PCa progression by activating the NF-κB signaling pathway.

Abstract GS5-08: Soluble E-cadherin: a novel prognostic biomarker and driver of brain metastasis in inflammatory breast cancer

Abstract Background: Inflammatory breast cancer (IBC) is a highly aggressive form of breast cancer with rapid onset and a strong propensity to spread to distant organs. Five-year overall survival (OS) rates remain poor, in part because of the high risk of brain metastasis: 19% of patients with IBC have brain metastases within the first 2 years after diagnosis. Our hypothesis for this study was that soluble E-cadherin (sEcad), an 80-kDa extracellular proteolytic fragment of full-length E-cadherin - a tumor promoter in IBC, is crucial for driving brain metastasis in IBC. Methods: We analyzed serum sEcad levels in from 348 IBC patients by ELISA. Four IBC cell lines [ER–/HER2+ (MDA-IBC3; SUM190) and ER–/HER2– (SUM149; BCX010)], human brain microvascular endothelial cells, and immortalized human astrocytes were used in this study. Stable overexpression of sEcad in IBC cell lines was achieved using lentiviral vectors. Mass spectrometry and Bio-ID-based proteomics assays, and RNA sequencing were used to identify sEcad-interacting proteins and potential mechanisms. In vivo, we studied tumor growth and brain metastasis in mice by injecting IBC cells into the mammary fatpad or tail vein, respectively, of SCID/Beige mice. Results: In IBC patients, higher serum sEcad levels correlated with poorer OS (p=0.02), earlier development of metastasis (p=0.006), and development of brain metastasis (p=0.04). On multivariable analysis, sEcad independently predicted OS (hazard ratio [HR]=2.07 [95% CI 1.19-3.60], p=0.01). In vitro, sEcad overexpression in IBC cell lines promoted anchorage-independent growth, migration, invasion, and resistance to anoikis. In vivo, sEcad-overexpressing SUM149 cells promoted primary tumor growth (p=0.007). Mice injected with sEcad-overexpressing MDA-IBC3 cells also had higher incidence of brain metastasis (100% vs 50%, p=0.03), metastatic burden (p=0.02) and number of metastases per mouse (p=0.0009), and had worse OS (p=0.0016), and brain metastasis-free survival (p=0.04), relative to controls. We further found that sEcad increased cancer cell adhesion to brain endothelial cells (p=0.01) and promoted induction of reactive astrocytes (as identified by high glial fibrillary acidic protein levels) in vitro and in vivo. Mechanistically, mass spectrometry and Bio-ID assays identified X-linked inhibitor of apoptosis protein (XIAP), a potent inhibitor of apoptotic cell death, as a novel binding partner of sEcad, which was validated through co-immunoprecipitation. Further analysis showed that sEcad bound to the BIR2 domain of XIAP. XIAP is the most potent and best-defined anti-apoptotic IAP family member, and it could induce NF-κB activation to inhibit tumor cell apoptosis Gene set enrichment analysis of RNA-seq profiling data showed activation of NF-kB signaling and downregulation of apoptotic pathways in the sEcad-overexpressing SUM149 cells compared with controls. Immunoblotting revealed that sEcad enhanced XIAP expression, activated NF-κB signaling, and inhibited cleavage of caspase-3 in IBC cells. Conclusions: We found that higher serum sEcad correlates with development of brain metastases and independently predicts poor OS in patients with IBC. We further found that sEcad promotes tumor growth and brain metastasis, perhaps via activation of XIAP/NF-κB signaling in breast cancer cells and promotion of endothelial cell adhesion and reactive astrocytosis in the brain microenvironment. These findings uncover a novel and crucial role for sEcad in brain metastasis and provide new insights and potential therapeutic targets for patients with metastatic IBC. Citation Format: Xiaoding Hu, Yun Xiong, Emilly S. Villodre, Juhee Song, Ganiraju C Manyam, Moises J Tacam, Jing Wang, Chandra Bartholomeusz, Debu Tripathy, Naoto T. Ueno, Wendy Woodward, Savitri Krishnamurthy, Junjie Chen, Bisrat Debeb. Soluble E-cadherin: a novel prognostic biomarker and driver of brain metastasis in inflammatory breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr GS5-08.

Fluoxetine Inhibits STAT3-mediated Survival and Invasion of Osteosarcoma Cells.

Osteosarcoma (OS) is a common primary malignancy of bone in adolescents. Its highly metastatic characteristics can lead to treatment failure and poor prognosis. Although standard treatments, including surgery, radiotherapy, and chemotherapy, have progressed in the past decade, treatment options to overcome metastatic progression remain sparse. Fluoxetine, an anti-depressant, has been widely used in patients with cancer for their mental issues and was reported to possess antitumor potential. However, the effect of fluoxetine on OS remains unclear. In this study, we used cell viability, invasion/migration transwell, wound-healing and aortic ring assays to identify the effects of fluoxetine on metastasis and progression in OS. Fluoxetine induced cytotoxicity in OS cells by activating both extrinsic/intrinsic apoptosis signaling pathways. Proliferation and anti-apoptosis-related factors such as cyclin D1 and X-linked inhibitor of apoptosis were suppressed by fluoxetine. Additionally, fluoxetine suppressed the invasive/migratory abilities of OS and inhibited the development of angiogenesis by reducing the phosphorylation of signal transducer and activator of transcription 3 (STAT3). Metastasis-associated factors, vascular endothelial growth factors, matrix metallopeptidase 2 and -9, were all reduced in OS cells by fluoxetine treatment. Fluoxetine not only induces cytotoxicity and apoptosis of OS cells, but also suppresses metastasis and angiogenesis by targeting STAT3.

Molecular identification and functional analysis of X-linked inhibitor of apoptosis -associated factor-1 (XAF1) in grass carp, Ctenopharyngodon idella

X-linked inhibitor of apoptosis protein (XIAP) -associated factor 1 (XAF1) is an interferon-stimulated gene which exhibits pro-apoptosis effect. In this study, XAF1 was characterized from grass carp Ctenopharyngodon idella and its expression pattern and function were analyzed. The open reading frame (orf) of XAF1 is 789 nucleotides (nt) encoding 262 amino acids. SMART online search results showed that a C2H2-type and six C2HC-type zinc-fingers were found in XAF1, however, the XAF1 of grass carp showed high sequence identity to zebrafish (71%), low sequence identity to tetrapods (21–22%). Rt-qPCR results showed that XAF1 was constitutively expressed in all tested organs/tissues with highest expression in blood. An inductive expression of XAF1 at mRNA level was observed in peripheral blood leucocytes (PBLs) and C. idellus kidney cells (CIKs) after treatment with C. idellus recombinant interferon-γ (rIFNg). Overexpressing XAF1 in CIKs exhibited resistance against grass carp reovirus (GCRV) and more sensitivity to cisplatin. These results implied a functional homologue of XAF1 in evolution, however the mechanism may require further investigation.

Tobacco nicotine promotes TRAIL resistance in lung cancer through SNHG5.

Tobacco nicotine use is carcinogenic and a well-known risk factor for lung cancer. However, whether tobacco nicotine can induce drug resistance in lung cancer is not clear. The objective of the present study was to identify the TNF-related apoptosis-inducing ligand (TRAIL) resistance of long noncoding RNAs (lncRNAs) that are differentially expressed in smokers and nonsmokers with lung cancer. The results suggested that the nicotine upregulated small nucleolar RNA host gene 5 (SNHG5) and markedly decreased the levels of cleaved caspase-3. The present study found that cytoplasm lncRNA SNHG5 overexpression was associated with TRAIL resistance in lung cancer and that SNHG5 can interact with X-linked inhibitor of apoptosis protein to promote TRAIL resistance. Therefore, nicotine promoted TRAIL resistance in lung cancer through SNHG5/X-linked inhibitor of apoptosis protein.

Overexpression of the X-Linked Inhibitor of Apoptosis Protein (XIAP) in Neurons Improves Cell Survival and the Functional Outcome after Traumatic Spinal Cord Injury.

Mechanical trauma to the spinal cord causes extensive neuronal death, contributing to the loss of sensory-motor and autonomic functions below the injury location. Apoptosis affects neurons after spinal cord injury (SCI) and is associated with increased caspase activity. Cleavage of X-linked inhibitor of apoptosis protein (XIAP) after SCI may contribute to this rise in caspase activity. Accordingly, we have shown that the elevation of XIAP resulted in increased neuronal survival after SCI and improved functional recovery. Therefore, we hypothesise that neuronal overexpression of XIAP can be neuroprotective after SCI with improved functional recovery. In line with this, studies of a transgenic mice with overexpression of XIAP in neurons revealed that higher levels of XIAP after spinal cord trauma favours neuronal survival, tissue preservation, and motor recovery after the spinal cord trauma. Using human SH-SY5Y cells overexpressing XIAP, we further showed that XIAP reduced caspase activity and apoptotic cell death after pro-apoptotic stimuli. In conclusion, this study shows that the levels of XIAP expression are an important factor for the outcome of spinal cord trauma and identifies XIAP as an important therapeutic target for alleviating the deleterious effects of SCI.

Caspase-8-driven apoptotic and pyroptotic crosstalk causes cell death and IL-1β release in X-linked inhibitor of apoptosis (XIAP) deficiency.

Genetic lesions in X-linked inhibitor of apoptosis (XIAP) pre-dispose humans to cell death-associated inflammatory diseases, although the underlying mechanisms remain unclear. Here, we report that two patients with XIAP deficiency-associated inflammatory bowel disease display increased inflammatory IL-1β maturation as well as cell death-associated caspase-8 and Gasdermin D (GSDMD) processing in diseased tissue, which is reduced upon patient treatment. Loss of XIAP leads to caspase-8-driven cell death and bioactive IL-1β release that is only abrogated by combined deletion of the apoptotic and pyroptotic cell death machinery. Namely, extrinsic apoptotic caspase-8 promotes pyroptotic GSDMD processing that kills macrophages lacking both inflammasome and apoptosis signalling components (caspase-1, -3, -7, -11 and BID), while caspase-8 can still cause cell death in the absence of both GSDMD and GSDME when caspase-3 and caspase-7 are present. Neither caspase-3 and caspase-7-mediated activation of the pannexin-1 channel, or GSDMD loss, prevented NLRP3 inflammasome assembly and consequent caspase-1 and IL-1β maturation downstream of XIAP inhibition and caspase-8 activation, even though the pannexin-1 channel was required for NLRP3 triggering upon mitochondrial apoptosis. These findings uncouple the mechanisms of cell death and NLRP3 activation resulting from extrinsic and intrinsic apoptosis signalling, revealhow XIAP loss can co-opt dual cell death programs, and uncover strategies for targeting the celldeath and inflammatory pathways that result from XIAP deficiency.

Caspase-3, Caspase-8 and XIAP Gene Expression in the Placenta: Exploring the Causes of Spontaneous Preterm Labour.

A better understanding of the pathogenesis of preterm birth (PTB) will allow us to lower the PTB rate, reducing perinatal morbidity and mortality. This article presents the hypothesis that premature placenta apoptosis could be a potential cause of PTB. We evaluated gene expression involved in apoptosis: caspase-3, caspase-8, and XIAP (X-linked inhibitor of apoptosis) in the placenta during pregnancy (n = 41), at the onset of preterm labour (n = 42), after preterm (n = 44) and term (n = 32) labour. We used RNA extraction, reverse transcription, and PCR. During pregnancy the gene expression of caspase-3 and caspase-8 is low, but XIAP is higher than the caspases. At the onset of preterm labour, we observed a significantly increased expression of both caspase-8 (10.7-fold, p < 0.01) and caspase-3 (2.5-fold, p < 0.01) and XIAP (3-fold; p < 0.05) compared with expression during pregnancy. Our study showed that during pregnancy, the expression of caspase genes in the placenta is low and probably controlled by high XIAP expression. At the onset of preterm labour, the expression of caspase genes increases sharply. This may initiate the onset of preterm labour.

Downregulation of NF-κB activation pathways using essential oil derived from Citrus pseudolimon: Anticancer and anti-inflammatory potential

This study focuses on isolating and characterizing the essential oil obtained from Citrus pseudolimon (C. pseudolimon) fruit peel for inhibition of cancer and inflammation through the downregulation of nuclear factor-kappa B (NF-κB) activation pathways. C. pseudolimon essential oil (CPEO) was isolated through steam-hydro distillation and characterized through GC-MS. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was performed to evaluate its anticancer potential against colon, leukemia, multiple myeloma, pancreatic, lung, and squamous carcinoma cells. The expression of proteins involved in cell proliferation like Cyclin E1 and intercellular adhesion molecule 1 (ICAM-1), anti-apoptotic proteins i.e. X-linked inhibitor of apoptosis protein (XIAP), capsapse-3, and poly-ADP ribose polymerase (PARP) was studied through western blotting analysis. The constituents were separated and limonene, limonene oxide, α-pinene, mentha-6,8-diene, 2-hydroperoxide, cis-carveol, and β-Myrcene were the major ones. CPEO exhibited a dose-dependent inhibition of cell proliferation up to 83–98% for 100 μg/mL oil. Flow cytometry analysis revealed that CPEO treatment in cancer cells induced a decrease in DNA contents in the synthesis (S-phase) of the cell cycle. Furthermore, CPEO downregulates the NF-κB; an inflammatory transcription marker and repressed the expression of genes regulated by NF-κB like Cyclin E1, ICAM-1, and XIAP responsible for cell proliferation and anti-apoptosis. Results revealed that CPEO adopt various mechanisms and routes like arresting of S-phase in cell cycle, induction of apoptosis, anti-inflammatory and anti-metastatic activities to induce death in cancer cells. The auspicious and persuasive bioactivities of CPEO showed that it might be very effective herbal medicine against this deadly disease.

Embelin: A multifaceted anticancer agent with translational potential in targeting tumor progression and metastasis.

Embelin, a natural para-benzoquinone product, is derived from plants of the Embelia genus, particularly Embelia ribes Burm.f. A staple in traditional medicinal formulations for centuries, Embelin's pharmacological actions are attributed to the hydroxyl benzoquinone present in its structure. Its therapeutic potential is bolstered by unique physical and chemical properties. Recently, Embelin, recognized as a non-peptidic, cell-permeable small inhibitor of the X-linked inhibitor of apoptosis protein (XIAP), has garnered significant attention for its anticancer activity. It demonstrates various anticancer mechanisms, such as apoptosis induction, cell cycle arrest, and autophagy, in different cancer types. Additionally, Embelin modulates several signal transduction pathways, including NF-κB, PI3Kinase/AKT, and STAT3, effectively inhibiting the proliferation of diverse cancer cell lines. This literature review illuminates the anticancer potential of Embelin, detailing its mechanisms of action and prospective clinical applications, based on relevant scientific literature from the past decade sourced from various electronic databases. See also the Graphical abstract(Fig. 1).