X-linked Inhibitor of Apoptosis (XIAP) Deficiency Complicated by Hemophagocytic Lymphohistiocytosis on Immunotherapy Leading to Acute Respiratory Distress Syndrome and Multiorgan Failure Secondary to Opportunistic Infections.

X-linked inhibitor of apoptosis (XIAP) deficiency is a rare primary immunodeficiency with a broad spectrum of clinical manifestations, including susceptibility to hemophagocytic lymphohistiocytosis (HLH), inflammatory bowel disease (IBD), hypogammaglobulinemia, and severe infections. We present a case of a 39-year-old male with a past medical history of XIAP deficiency complicated by HLH, Crohn's disease, and hypogammaglobulinemia, who developed acute respiratory distress syndrome (ARDS) due to Pneumocystis jiroveci pneumonia (PJP) and concurrent multiorgan failure due to disseminated Mycobacterium avium intracellulare (MAI) infection. This case highlights the challenges in managing XIAP deficiency, emphasizing the importance of early recognition, and the need for further research to improve outcomes in this population.

(2,6-Dimethylphenyl)arsonic Acid Induces Apoptosis through the Mitochondrial Pathway, Downregulates XIAP, and Overcomes Multidrug Resistance to Cytostatic Drugs in Leukemia and Lymphoma Cells In Vitro.

Cancer treatment is greatly challenged by drug resistance, highlighting the need for novel drug discoveries. Here, we investigated novel organoarsenic compounds regarding their resistance-breaking and apoptosis-inducing properties in leukemia and lymphoma. Notably, the compound (2,6-dimethylphenyl)arsonic acid (As2) demonstrated significant inhibition of cell proliferation and induction of apoptosis in leukemia and lymphoma cells while sparing healthy leukocytes. As2 reached half of its maximum activity (AC50) against leukemia cells at around 6.3 µM. Further experiments showed that As2 overcomes multidrug resistance and sensitizes drug-resistant leukemia and lymphoma cell lines to treatments with the common cytostatic drugs vincristine, daunorubicin, and cytarabine at low micromolar concentrations. Mechanistic investigations of As2-mediated apoptosis involving FADD (FAS-associated death domain)-deficient or Smac (second mitochondria-derived activator of caspases)/DIABLO (direct IAP binding protein with low pI)-overexpressing cell lines, western blot analysis of caspase-9 cleavage, and measurements of mitochondrial membrane integrity identified the mitochondrial apoptosis pathway as the main mode of action. Downregulation of XIAP (x-linked inhibitor of apoptosis protein) and apoptosis induction independent of Bcl-2 (B-cell lymphoma 2) and caspase-3 expression levels suggest the activation of additional apoptosis-promoting mechanisms. Due to the selective apoptosis induction, the synergistic effects with common anti-cancer drugs, and the ability to overcome multidrug resistance in vitro, As2 represents a promising candidate for further preclinical investigations with respect to refractory malignancies.

Deoxyshikonin triggers apoptosis in cervical cancer cells through p38 MAPK-mediated caspase activation.

Deoxyshikonin (DSK) is a biological component derived from Lithospermum erythrorhizon. Although DSK possesses potential anticancer activities, whether DSK exerts anticancer effects on cervical cancer cells is incompletely explored. This study was aimed to investigate the anticancer activity of DSK against cervical cancer cells and its molecular mechanisms. Cell viability was evaluated by MTT assay. Level of phosphorylation and protein was determined using Western blot. Involvement of signaling kinases was assessed by specific inhibitors. Our results revealed that DSK reduced viability of human cervical cell in a dose-dependent fashion. Meanwhile, DSK significantly elicited apoptosis of HeLa and SiHa cells. Apoptosis microarray was used to elucidate the involved pathways, and the results showed that DSK dose-dependently diminished cellular inhibitor of apoptosis protein 1 (cIAP1), cIAP2, and XIAP, and induced cleavage of poly(ADP-ribose) polymerase (PARP) and caspase-8/9/3. Furthermore, we observed that DSK significantly triggered activation of ERK, JNK, and p38 MAPK (p38), and only inhibition of p38 diminished the DSK-mediated pro-caspases cleavage. Taken together, our results demonstrate that DSK has anti-cervical cancer effects via the apoptotic cascade elicited by downregulation of IAPs and p38-mediated caspase activation. This suggests that DSK could act as an adjuvant to facilitate cervical cancer management.

CD62-L down-regulation after L18-MDP stimulation as a complementary flow cytometry functional assay for the diagnosis of XIAP deficiency.

X-linked inhibitor of apoptosis (XIAP) deficiency is an infrequent inborn error of immunity caused by mutations in XIAP gene. Most cases present with absence of XIAP protein which can be detected by flow cytometry (FC), representing a rapid diagnostic method. However, since some genetic defects may not preclude protein expression, it is important to include a complementary functional test in the laboratory workup of these patients. L-selectin (CD62-L) is a molecule that is cleaved from the surface membrane of leukocytes upon stimulation of different receptors such as toll like receptors (TLRs) and nucleotide-binding oligomerization domain-like receptors (NLRs), including NOD2. Considering that XIAP deficiency impairs NOD2 signaling, we decided to assess CD62-L down-regulation by FC post-stimulation of neutrophils and monocytes with L18-muramyl Di-Peptide (L18-MDP), a NOD2 specific agonist, in order to develop a novel assay for the functional evaluation of patients with suspicion of XIAP defects. Whole blood samples from 20 healthy controls (HC) and four patients with confirmed molecular diagnosis of XIAP deficiency were stimulated with 200 ng/mL of L18-MDP for 2 h. Stimulation with 100 ng/mL of lipopolysaccharide (LPS) was carried out in parallel as a positive control of CD62-L shedding. CD62-L expression was evaluated by FC using an anti CD62-L- antibody and down-regulation was assessed by calculating the difference in CD62-L expression before and after stimulation, both in terms of percentage of CD62-L expressing cells (Δ%CD62-L) and median fluorescence intensity (ΔMFI%). Neutrophils and monocytes from XIAP deficient patients displayed a significantly diminished response to L18-MDP stimulation compared with HC (p < 0.0001), indicating a severely altered mechanism of CD62-L down-regulation following activation of NOD2-XIAP axis. On the other hand, the response to LPS stimulation was comparable between patients and heathy controls, suggesting preserved CD62-L shedding with a different stimulus. FC detection of CD62-L down-regulation in monocytes and neutrophils after whole blood stimulation with L18-MDP results in an effective and rapid functional test for the identification of XIAP deficient patients.

A grape-supplemented diet prevented ultraviolet (UV) radiation-induced cataract by regulating Nrf2 and XIAP pathways.

The purpose of this study is to investigate if grape consumption, in the form of grape powder (GP), could protect against ultraviolet (UV)-induced cataract. Mice were fed with the regular diet, sugar placebo diet, or a grape diet (regular diet supplemented with 5%, 10%, and 15% GP) for 3 months. The mice were then exposed to UV radiation to induce cataract. The results showed that the GP diet dose-dependently inhibited UV-induced cataract and preserved glutathione pools. Interestingly, UV-induced Nrf2 activation was abolished in the groups on the GP diet, suggesting GP consumption may improve redox homeostasis in the lens, making Nrf2 activation unnecessary. For molecular target prediction, a total of 471 proteins regulated by GP were identified using Agilent Literature Search (ALS) software. Among these targets, the X-linked inhibitor of apoptosis (XIAP) was correlated with all of the main active ingredients of GP, including resveratrol, catechin, quercetin, and anthocyanins. Our data confirmed that GP prevented UV-induced suppression of XIAP, indicating that XIAP might be one of the critical molecular targets of GP. In conclusion, this study demonstrated that GP protected the lens from UV-induced cataract development in mice. The protective effects of GP may be attributed to its ability to improve redox homeostasis and activate the XIAP-mediated antiapoptotic pathway.

Sterigmatocystin induces autophagic and apoptotic cell death of liver cancer cells via downregulation of XIAP.

XIAP, or the X-linked Inhibitor of Apoptosis Protein, is the most extensively studied member within the IAP gene family. It possesses the capability to impede apoptosis through direct inhibition of caspase activity. Various kinds of cancers overexpress XIAP to enable cancer cells to avoid apoptosis. Consequently, the inhibition of XIAP holds significant clinical implications for the development of anti-tumor medications and the treatment of cancer. In this study, sterigmatocystin, a natural compound obtained from the genus asperigillus, was demonstrated to be able to induce apoptotic and autophagic cell death in liver cancer cells. Mechanistically, sterigmatocystin induces apoptosis by downregulation of XIAP expression. Additionally, sterigmatocystin treatment induces cell cycle arrest, blocks cell proliferation, and slows down colony formation in liver cancer cells. Importantly, sterigmatocystin exhibits a remarkable therapeutic effect in a nude mice model. Our findings revealed a novel mechanism through which sterigmatocystin induces apoptotic and autophagic cell death of liver cancer cells by suppressing XIAP expression, this offers a promising therapeutic approach for treating liver cancer patients.

ARTS and small-molecule ARTS mimetics upregulate p53 levels by promoting the degradation of XIAP.

Mutations resulting in decreased activity of p53 tumor suppressor protein promote tumorigenesis. P53 protein levels are tightly regulated through the Ubiquitin Proteasome System (UPS). Several E3 ligases were shown to regulate p53 stability, including MDM2. Here we report that the ubiquitin E3 ligase XIAP (X-linked Inhibitors of Apoptosis) is a direct ligase for p53 and describe a novel approach for modulating the levels of p53 by targeting the XIAP pathway. Using in vivo (live-cell) and in vitro (cell-free reconstituted system) ubiquitylation assays, we show that the XIAP-antagonist ARTS regulates the levels of p53 by promoting the degradation of XIAP. XIAP directly binds and ubiquitylates p53. In apoptotic cells, ARTS inhibits the ubiquitylation of p53 by antagonizing XIAP. XIAP knockout MEFs express higher p53 protein levels compared to wild-type MEFs. Computational screen for small molecules with high affinity to the ARTS-binding site within XIAP identified a small-molecule ARTS-mimetic, B3. This compound stimulates apoptosis in a wide range of cancer cells but not normal PBMC (Peripheral Blood Mononuclear Cells). Like ARTS, the B3 compound binds to XIAP and promotes its degradation via the UPS. B3 binding to XIAP stabilizes p53 by disrupting its interaction with XIAP. These results reveal a novel mechanism by which ARTS and p53 regulate each other through an amplification loop to promote apoptosis. Finally, these data suggest that targeting the ARTS binding pocket in XIAP can be used to increase p53 levels as a new strategy for developing anti-cancer therapeutics.

Moracin D suppresses cell growth and induces apoptosis via targeting the XIAP/PARP1 axis in pancreatic cancer.

BACKGROUND: Pancreatic cancer, a tumor with a high metastasis rate and poor prognosis, is among the deadliest human malignancies. Investigating effective drugs for their treatment is imperative. Moracin D, a natural benzofuran compound isolated from Morus alba L., shows anti-inflammation and anti-breast cancer properties and is effective against Alzheimer's disease. However, the effect and mechanism of Moracin D action in pancreatic cancer remain obscure. PURPOSE: To investigate the function and molecular mechanism of Moracin D action in repressing the malignant progression of pancreatic cancer. METHODS: Pancreatic cancer cells were treated with Moracin D, and cell proliferation was evaluated by cell counting kit-8 (CCK-8) and immunofluorescence assays. The clonogenicity of pancreatic cancer cells was assessed based on plate colony formation and soft agar assay. Flow cytometry was used to detect cell apoptosis. The expression of proteins related to the apoptosis pathway was determined by Western blot analysis. Moracin D and XIAP were subjected to docking by auto-dock molecular docking analysis. Ubiquitination levels of XIAP and the interaction of XIAP and PARP1 were assessed by co-immunoprecipitation analysis. Moracin D's effects on tumorigenicity were assessed by a tumor xenograft assay. RESULTS: Moracin D inhibited cell proliferation, induced cell apoptosis, and regulated the protein expression of molecules involved in caspase-dependent apoptosis pathways. Moracin D suppressed clonogenicity and tumorigenesis of pancreatic cancer cells. Mechanistically, XIAP could interact with PARP1 and stabilize PARP1 by controlling its ubiquitination levels. Moracin D diminished the stability of XIAP and decreased the expression of XIAP by promoting proteasome-dependent XIAP degradation, further blocking the XIAP/PARP1 axis and repressing the progression of pancreatic cancer. Moracin D could dramatically improve the chemosensitivity of gemcitabine in pancreatic cancer cells. CONCLUSION: Moracin D repressed cell growth and tumorigenesis, induced cell apoptosis, and enhanced the chemosensitivity of gemcitabine through the XIAP/PARP1 axis in pancreatic cancer. Moracin D is a potential therapeutic agent or adjuvant for pancreatic cancer.

Systematic analysis of PANoptosis-related genes identifies XIAP as a functional oncogene in breast cancer.

BACKGROUND: Breast cancer (BC) is the most prevalent malignant disease affecting women globally. PANoptosis, a novel form of cell death combining features of pyroptosis, apoptosis, and necroptosis, has recently gained attention. However, its precise function in BC and the predictive values of PANoptosis-related genes remain unclear. METHODS: We used the expression data and clinical information of BC tissues or normal breast tissues from public databases, and then successfully developed and verified a BC PANoptosis-related risk model through a combination of univariate Cox regression, least absolute shrinkage and selection operator (LASSO) regression, and Kaplan-Meier (KM) analysis. A nomogram was constructed to estimate survival probability, and its accuracy was assessed using calibration curves. RESULTS: Among 37 PANoptosis-related genes, we identified 4 differentially expressed genes related to overall survival (OS). Next, a risk model incorporating these four PANoptosis-related genes was established. Patients were stratified into low/high-risk groups based on the median risk score, with the low-risk group showing better prognoses and higher levels of immune infiltration. Utilizing the risk score and clinical features, we developed a nomogram to predict 1-, 3- and 5-year survival probability. X-linked inhibitor of apoptosis protein (XIAP) emerged as a potentially risky factor with the highest hazard ratio. In vitro experiments demonstrated that XIAP inhibition enhances the antitumor effect of doxorubicin through the PANoptosis pathway. CONCLUSION: PANoptosis holds an important role in BC prognosis and treatment.

XIAP overexpressing inflammatory breast cancer patients have high infiltration of immunosuppressive subsets and increased TNFR1 signaling targetable with Birinapant.

OBJECTIVE: To assess the expression pattern of X-linked inhibitor of apoptosis protein (XIAP), a cellular stress sensor, and delineate the associated changes in the tumor immune microenvironment (TiME) for prognostic value and new therapeutic targets in inflammatory breast cancer (IBC). METHODS: Immunohistochemistry was conducted to assess the spatial localization of immune subsets, XIAP, and PDL1 expression in IBC and non-inflammatory breast cancer (nIBC) pretreatment tumors (n = 142). Validation and further exploration were performed by gene expression analysis of patient tumors along with signaling studies in a co-culture model. RESULTS: High XIAP in 37/81 IBC patients correlated significantly with high PD-L1, increased infiltration of FOXP3+ Tregs, CD163+ tumor-associated macrophages (TAMs), low CD8/CD163 ratio in both tumor stroma (TS) and invasive margins (IM), and higher CD8+ T cells and CD79α+ B cells in the IM. Gene set enrichment analysis identified cellular stress response- and inflammation-related genes along with tumor necrosis factor receptor 1 (TNFR1) expression in high-XIAP IBC tumors. Induction of TNFR1 and XIAP was observed when patient-derived SUM149 IBC cells were co-cultured with human macrophage-conditioned media simulating TAMs, further demonstrating that the TNF-α signaling pathway is a likely candidate governing TAM-induced XIAP overexpression in IBC cells. Finally, addition of Birinapant, a pan IAP antagonist, induced cell death in the pro-survival cytokine-enriched conditions. CONCLUSION: Using immunophenotyping and gene expression analysis in patient biospecimens along with in silico modeling and a preclinical model with a pan-IAP antagonist, this study revealed an interplay between increased TAMs, TNF-α signaling, and XIAP activation during (immune) stress in IBC. These data demonstrate the potential of IAP antagonists as immunomodulators for improving IBC therapeutic regimens.

Enhanced translocation of TRIM32 to mitochondria sensitizes dopaminergic neuronal cells to apoptosis during stress conditions in Parkinson's disease.

Parkinson's disease (PD) is a chronic neurodegenerative disease characterized by progressive loss of dopamine-producing neurons from the substantia nigra region of the brain. Mitochondrial dysfunction is one of the major causes of oxidative stress and neuronal cell death in PD. E3 ubiquitin ligases such as Parkin (PRKN) modulate mitochondrial quality control in PD; however, the role of other E3 ligases associated with mitochondria in the regulation of neuronal cell death in PD has not been explored. The current study investigated the role of TRIM32, RING E3 ligase, in sensitization to oxidative stress-induced neuronal apoptosis. The expression of TRIM32 sensitizes SH-SY5Y dopaminergic cells to rotenone and 6-OHDA-induced neuronal death, whereas the knockdown increased cell viability under PD stress conditions. The turnover of TRIM32 is enhanced under PD stress conditions and is mediated by autophagy. TRIM32 translocation to mitochondria is enhanced under PD stress conditions and localizes on the outer mitochondrial membrane. TRIM32 decreases complex-I assembly and activity as well as mitochondrial reactive oxygen species (ROS) and ATP levels under PD stress. Deletion of the RING domain of TRIM32 enhanced complex I activity and rescued ROS levels and neuronal viability under PD stress conditions. TRIM32 decreases the level of XIAP, and co-expression of XIAP with TRIM32 rescued the PD stress-induced cell death and mitochondrial ROS level. In conclusion, turnover of TRIM32 increases during stress conditions and translocation to mitochondria is enhanced, regulating mitochondrial functions and neuronal apoptosis by modulating the level of XIAP in PD.

Design, in silico evaluation, and in vitro verification of new bivalent Smac mimetics with pro-apoptotic activity.

Bivalent Smac mimetics have been shown to possess binding affinity and pro-apoptotic activity similar to or more potent than that of native Smac, a protein dimer able to neutralize the anti-apoptotic activity of an inhibitor of caspase enzymes, XIAP, which endows cancer cells with resistance to anticancer drugs. We design five new bivalent Smac mimetics, which are formed by various linkers tethering two diazabicyclic cores being the IAP binding motifs. We built in silico models of the five mimetics by the TwistDock workflow and evaluated their conformational tendency, which suggests that compound 3, whose linker is n-hexylene, possess the highest binding potency among the five. After synthesis of these compounds, their ability in tumour cell growth inhibition and apoptosis induction displayed in experiments with SK-OV-3 and MDA-MB-231 cancer cell lines confirms our prediction. Among the five mimetics, compound 3 displays promising pro-apoptotic activity and deserves further optimization.

[Retracted] Embelin-induced brain glioma cell apoptosis and cell cycle arrest via the mitochondrial pathway.

Following the publication of the above paper, it was drawn to the Editor's attention by a concerned reader that the flow cytometric data shown in Fig. 4A on p. 2475 were strikingly similar to data appearing in another article written by different authors at different research institutes which had already been published. Owing to the fact that the contentious data in the above article had already been published elsewhere prior to its submission to Oncology Reports, the Editor has decided that this paper should be retracted from the Journal. The authors were asked for an explanation to account for these concerns, but the Editorial Office did not receive a reply. The Editor apologizes to the readership for any inconvenience caused. [Oncology Reports 29: 2473­2478, 2013; DOI: 10.3892/or.2013.2369].

SP1-stimulated miR-208a-5p aggravates sepsis-induced myocardial injury via targeting XIAP.

The development of sepsis can lead to many organ dysfunction and even death. Myocardial injury is one of the serious complications of sepsis leading to death. New evidence suggests that microRNAs (miRNAs) play a critical role in infection myocardial injury. However, the mechanism which miR-208a-5p regulates sepsis-induced myocardial injury remains unclear. To mimic sepsis-induced myocardial injury in vitro, rat primary cardiomyocytes were treated with LPS. Cell viability and apoptosis were tested by CCK-8 and flow cytometry, respectively. The secretion of inflammatory factors was analyzed by ELISA. mRNA and protein levels were detected by RT-qPCR and Western blotting. The interaction among SP1, XIAP and miR-208a-5p was detected using dual luciferase report assay. Ultrasonic analysis and HE staining was performed to observe the effect of miR-208a-5p in sepsis-induced rats. Our findings indicated that miR-208a-5p expression in primary rat cardiomyocytes was increased by LPS. MiR-208a-5p inhibitor reversed LPS-induced cardiomyocytes injury through inhibiting the apoptosis. Furthermore, the inflammatory injury in cardiomyocytes was induced by LPS, which was rescued by miR-208a-5p inhibitor. In addition, downregulation of miR-208a-5p improved LPS-induced sepsis myocardial injury in vivo. Mechanistically, XIAP might be a target gene of miR-208a-5p. SP1 promoted transcription of miR-208a by binding to the miR-208a promoter region. Moreover, silencing of XIAP reversed the regulatory of miR-208a-5p inhibitor on cardiomyocytes injury. To sum up, those findings revealed silencing of miR-208a-5p could alleviate sepsis-induced myocardial injury, which would grant a new process for the treatment of sepsis.

Hellebrigenin induces oral cancer cell apoptosis by modulating MAPK signalling and XIAP expression.

Oral squamous cell carcinoma (OSCC), which accounts for 90% of all oral cancers, has become a public health crisis worldwide. despite advances in therapeutic interventions, the prognosis remains poor for advanced-stage OSCC. In this study, we investigate the anticancer activity and the mode of action of hellebrigenin in human OSCC. The findings demonstrated that hellebrigenin exerted cytotoxic effects in OSCC cells through cell cycle arrest at the G2/M phase and downregulation of cell cycle-related proteins (cyclins A2, B1 and D3, Cdc2, CDK4 and CDK6). Moreover, hellebrigenin caused activation of PARP and caspase 3, 8 and 9, followed by downregulation of antiapoptotic proteins (Bcl-2 and Bcl-xL) and upregulation of pro-apoptotic proteins (Bax and Bak). The hellebrigenin treatment also increased Fas, DR5, DcR2 and DcR3 expressions in oral cancer cells, indicating the compound causes oral cancer cell apoptosis through both intrinsic and extrinsic pathways. Regarding upstream signalling, hellebrigenin was found to reduce the phosphorylation of ERK, p38, and JNK, indicating that hellebrigenin triggers caspase-mediated apoptosis by downregulating MAPK signalling pathway. Finally, the human apoptosis array findings revealed that hellebrigenin specifically suppressed the expression of XIAP to execute its pro-apoptotic activities. Taken together, the study suggests that hellebrigenin can act as a potent anticancer compound in human OSCC.

Apoptosis-related factors are relevant to progression of pancreatic neuroendocrine tumors.

BACKGROUND: Multidisciplinary therapy centered on antitumor drugs is indicated in patients with unresectable pancreatic neuroendocrine tumors (PanNET). However, the criteria for selection of optimal therapeutic agents is controversial. The aim of this study was to assess the malignancy of PanNET for optimal therapeutic drug selection. METHODS: Forty-seven patients with PanNET who underwent surgery were reviewed retrospectively, and immunohistochemical characteristics, including expression of GLUT1, SSTR2a, SSTR5, Survivin, X-chromosome-linked inhibitor of apoptosis protein (XIAP), and Caspase3 in the resected specimens, were investigated. Relapse-free survival (RFS) and overall survival (OS) were evaluated with regard to the characteristics using the Kaplan-Meier method and compared with the log-rank test. RESULTS: GLUT1 expression showed significant correlation with sex (p = 0.036) and mitotic rate (p = 0.048). Survivin and XIAP expression showed significant correlation with T-stage (p = 0.014 and 0.009), p-Stage (p = 0.028 and 0.045), and mitotic rate (p = 0.023 and 0.007). XIAP expression also significantly influenced OS (p = 0.044). CONCLUSIONS: Survivin and XIAP correlated with grade of malignancy, and expression of XIAP in particular was associated with a poor prognosis. Expression of these proteins may be a useful indicator to select optimal therapeutic agents in PanNET.

Vibrio parahaemolyticus thermostable direct haemolysin induces non-classical programmed cell death despite caspase activation.

Thermostable direct haemolysin (TDH) is the key virulence factor secreted by the human gastroenteric bacterial pathogen Vibrio parahaemolyticus. TDH is a membrane-damaging pore-forming toxin. It evokes potent cytotoxicity, the mechanism of which still remains under-explored. Here, we have elucidated the mechanistic details of cell death response elicited by TDH. Employing Caco-2 intestinal epithelial cells and THP-1 monocytic cells, we show that TDH induces some of the hallmark features of apoptosis-like programmed cell death. TDH triggers caspase-3 and 7 activations in the THP-1 cells, while caspase-7 activation is observed in the Caco-2 cells. Interestingly, TDH appears to induce caspase-independent cell death. Higher XIAP level and lower Smac/Diablo level upon TDH intoxication provide plausible explanation for the functional inability of caspases in the THP-1 cells, in particular. Further exploration reveals that mitochondria play a central role in the TDH-induced cell death. TDH triggers mitochondrial damage, resulting in the release of AIF and endonuclease G, responsible for the execution of caspase-independent cell death. Among the other critical mediators of cell death, ROS is found to play an important role in the THP-1 cells, while PARP-1 appears to play a critical role in the Caco-2 cells. Altogether, our work provides critical new insights into the mechanism of cell death induction by TDH, showing a common central theme of non-classical programmed cell death. Our study also unravels the interplay of crucial molecules in the underlying signalling processes. Our findings add valuable insights into the role of TDH in the context of the host-pathogen interaction processes.

Multi-kinase compensation rescues EGFR knockout in a cell line model of head and neck squamous cell carcinoma.

BACKGROUND: Head and neck squamous cell carcinoma (HNSCC) is a debilitating disease with poor survival rates. While the epidermal growth factor receptor (EGFR)-targeting antibody Cetuximab is approved for treatment, responses are limited and the molecular mechanisms driving resistance remain incompletely understood. METHODS: To better understand how cells survive without EGFR activity, we developed an EGFR knockout derivative of the UM-SCC-92 cell line using CRISPR/Cas9 technology. We then characterized changes to the transcriptome with RNAseq and changes in response to kinase inhibitors with resazurin cell viability assays. Finally, we tested if inhibitors with activity in the EGFR knockout model also had synergistic activity in combination with EGFR inhibitors in either wild type UM-SCC-92 cells or a known Cetuximab-resistant model. RESULTS: Functional and molecular analysis showed that knockout cells had decreased cell proliferation, upregulation of FGFR1 expression, and an enhanced mesenchymal phenotype. In fact, expression of common EMT genes including VIM, SNAIL1, ZEB1 and TWIST1 were all upregulated in the EGFR knockout. Surprisingly, EGFR knockout cells were resistant to FGFR inhibitor monotherapies, but sensitive to combinations of FGFR and either XIAP or IGF-1R inhibitors. Accordingly, both wild type UM-SCC-92 and Cetuximab-resistant UM-SCC-104 cells with were sensitive to combined inhibition of EGFR, FGFR and either XIAP or IGF-1R. CONCLUSIONS: These data offer insights into EGFR inhibitor resistance and show that resistance to EGFR knockout likely occurs through a complex network of kinases. Future studies of cetuximab-resistant HNSCC tumors are warranted to determine if this EMT phenotype and/or multi-kinase resistance is observed in patients.

Targeting Inhibitor of Apoptosis Proteins to Overcome Chemotherapy Resistance-A Marriage between Targeted Therapy and Cytotoxic Chemotherapy.

Precision oncology is the ultimate goal of cancer treatment, i.e., to treat cancer and only cancer, leaving all the remaining cells and tissues as intact as possible. Classical chemotherapy and radiotherapy, however, are still effective in many patients with cancer by effectively inducing apoptosis of cancer cells. Cancer cells might resist apoptosis via the anti-apoptotic effects of the inhibitor of apoptosis proteins. Recently, the inhibitors of those proteins have been developed with the goal of enhancing the cytotoxic effects of chemotherapy and radiotherapy, and one of them, xevinapant, has already demonstrated effectiveness in a phase II clinical trial. This class of drugs represents an example of synergism between classical cytotoxic chemo- and radiotherapy and new targeted therapy.

MicroRNAs Regulate Inhibitor of Apoptosis Proteins (IAPs) in Colorectal Cancer.

Colorectal cancer (CRC) is the second most common cause of cancer mortality, with approximately 1.9 million new cases and 0.9 million deaths globally in 2020. One of the potential ways to treat colorectal cancer may be through the use of molecular methods to induce cell apoptosis. Apoptosis is a natural cellular event that regulates the growth and proliferation of body cells and prevents cancer. In this pathway, several molecules are involved; one group promotes this process, and some molecules that are representative of inhibitors of apoptosis proteins (IAPs) inhibit apoptosis. The most important human IAPs include c-IAP1, c-IAP2, NAIP, Survivin, XIAP, Bruce, ILP-2, and Livin. Several studies have shown that the inhibition of IAPs may be useful in cancer treatment. MicroRNAs (miRNAs) may be effective in regulating the expression of various proteins, including those of the IAPs family; they are a large subgroup of non-coding RNAs that are evolutionarily conserved. Therefore, in this review, the miRNAs that may be used to target IAPs in colorectal cancer were discussed.