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Chinese Journal of Cancer Jun 2017Multidrug resistance (MDR) occurs frequently after long-term chemotherapy, resulting in refractory cancer and tumor recurrence. Therefore, combatting MDR is an important... (Review)
Review
Multidrug resistance (MDR) occurs frequently after long-term chemotherapy, resulting in refractory cancer and tumor recurrence. Therefore, combatting MDR is an important issue. Autophagy, a self-degradative system, universally arises during the treatment of sensitive and MDR cancer. Autophagy can be a double-edged sword for MDR tumors: it participates in the development of MDR and protects cancer cells from chemotherapeutics but can also kill MDR cancer cells in which apoptosis pathways are inactive. Autophagy induced by anticancer drugs could also activate apoptosis signaling pathways in MDR cells, facilitating MDR reversal. Therefore, research on the regulation of autophagy to combat MDR is expanding and is becoming increasingly important. We summarize advanced studies of autophagy in MDR tumors, including the variable role of autophagy in MDR cancer cells.
Topics: Antineoplastic Agents; Apoptosis; Autophagy; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Humans; Neoplasms
PubMed: 28646911
DOI: 10.1186/s40880-017-0219-2 -
Nature Reviews. Neurology Jan 2021Progressive multifocal leukoencephalopathy (PML) is a devastating CNS infection caused by JC virus (JCV), a polyomavirus that commonly establishes persistent,... (Review)
Review
Progressive multifocal leukoencephalopathy (PML) is a devastating CNS infection caused by JC virus (JCV), a polyomavirus that commonly establishes persistent, asymptomatic infection in the general population. Emerging evidence that PML can be ameliorated with novel immunotherapeutic approaches calls for reassessment of PML pathophysiology and clinical course. PML results from JCV reactivation in the setting of impaired cellular immunity, and no antiviral therapies are available, so survival depends on reversal of the underlying immunosuppression. Antiretroviral therapies greatly reduce the risk of HIV-related PML, but many modern treatments for cancers, organ transplantation and chronic inflammatory disease cause immunosuppression that can be difficult to reverse. These treatments - most notably natalizumab for multiple sclerosis - have led to a surge of iatrogenic PML. The spectrum of presentations of JCV-related disease has evolved over time and may challenge current diagnostic criteria. Immunotherapeutic interventions, such as use of checkpoint inhibitors and adoptive T cell transfer, have shown promise but caution is needed in the management of immune reconstitution inflammatory syndrome, an exuberant immune response that can contribute to morbidity and death. Many people who survive PML are left with neurological sequelae and some with persistent, low-level viral replication in the CNS. As the number of people who survive PML increases, this lack of viral clearance could create challenges in the subsequent management of some underlying diseases.
Topics: Adoptive Transfer; Humans; Immune Checkpoint Inhibitors; JC Virus; Leukoencephalopathy, Progressive Multifocal; T-Lymphocytes
PubMed: 33219338
DOI: 10.1038/s41582-020-00427-y -
Immunity Jan 2019Checkpoint blockade mediates a proliferative response of tumor-infiltrating CD8 T lymphocytes (TILs). The origin of this response has remained elusive because chronic...
Checkpoint blockade mediates a proliferative response of tumor-infiltrating CD8 T lymphocytes (TILs). The origin of this response has remained elusive because chronic activation promotes terminal differentiation or exhaustion of tumor-specific T cells. Here we identified a subset of tumor-reactive TILs bearing hallmarks of exhausted cells and central memory cells, including expression of the checkpoint protein PD-1 and the transcription factor Tcf1. Tcf1PD-1 TILs mediated the proliferative response to immunotherapy, generating both Tcf1PD-1 and differentiated Tcf1PD-1 cells. Ablation of Tcf1PD-1 TILs restricted responses to immunotherapy. Tcf1 was not required for the generation of Tcf1PD-1 TILs but was essential for the stem-like functions of these cells. Human TCF1PD-1 cells were detected among tumor-reactive CD8 T cells in the blood of melanoma patients and among TILs of primary melanomas. Thus, immune checkpoint blockade relies not on reversal of T cell exhaustion programs, but on the proliferation of a stem-like TIL subset.
Topics: Animals; Antibodies, Monoclonal; CD8-Positive T-Lymphocytes; Cell Differentiation; Cell Proliferation; Hepatitis A Virus Cellular Receptor 2; Hepatocyte Nuclear Factor 1-alpha; Humans; Immunotherapy; Lymphocytes, Tumor-Infiltrating; Melanoma; Melanoma, Experimental; Mice; Mice, Inbred C57BL; Programmed Cell Death 1 Receptor; Stem Cells; T-Lymphocyte Subsets
PubMed: 30635237
DOI: 10.1016/j.immuni.2018.12.021 -
Nature Nov 2014Ischaemia-reperfusion injury occurs when the blood supply to an organ is disrupted and then restored, and underlies many disorders, notably heart attack and stroke.... (Comparative Study)
Comparative Study
Ischaemia-reperfusion injury occurs when the blood supply to an organ is disrupted and then restored, and underlies many disorders, notably heart attack and stroke. While reperfusion of ischaemic tissue is essential for survival, it also initiates oxidative damage, cell death and aberrant immune responses through the generation of mitochondrial reactive oxygen species (ROS). Although mitochondrial ROS production in ischaemia reperfusion is established, it has generally been considered a nonspecific response to reperfusion. Here we develop a comparative in vivo metabolomic analysis, and unexpectedly identify widely conserved metabolic pathways responsible for mitochondrial ROS production during ischaemia reperfusion. We show that selective accumulation of the citric acid cycle intermediate succinate is a universal metabolic signature of ischaemia in a range of tissues and is responsible for mitochondrial ROS production during reperfusion. Ischaemic succinate accumulation arises from reversal of succinate dehydrogenase, which in turn is driven by fumarate overflow from purine nucleotide breakdown and partial reversal of the malate/aspartate shuttle. After reperfusion, the accumulated succinate is rapidly re-oxidized by succinate dehydrogenase, driving extensive ROS generation by reverse electron transport at mitochondrial complex I. Decreasing ischaemic succinate accumulation by pharmacological inhibition is sufficient to ameliorate in vivo ischaemia-reperfusion injury in murine models of heart attack and stroke. Thus, we have identified a conserved metabolic response of tissues to ischaemia and reperfusion that unifies many hitherto unconnected aspects of ischaemia-reperfusion injury. Furthermore, these findings reveal a new pathway for metabolic control of ROS production in vivo, while demonstrating that inhibition of ischaemic succinate accumulation and its oxidation after subsequent reperfusion is a potential therapeutic target to decrease ischaemia-reperfusion injury in a range of pathologies.
Topics: Adenosine Monophosphate; Animals; Aspartic Acid; Citric Acid Cycle; Disease Models, Animal; Electron Transport; Electron Transport Complex I; Fumarates; Ischemia; Malates; Male; Metabolomics; Mice; Mitochondria; Myocardial Infarction; Myocardium; Myocytes, Cardiac; NAD; Reactive Oxygen Species; Reperfusion Injury; Stroke; Succinate Dehydrogenase; Succinic Acid
PubMed: 25383517
DOI: 10.1038/nature13909 -
Cell Death and Differentiation Feb 2021The BAP1 gene has emerged as a major tumor suppressor mutated with various frequencies in numerous human malignancies, including uveal melanoma, malignant pleural... (Review)
Review
The BAP1 gene has emerged as a major tumor suppressor mutated with various frequencies in numerous human malignancies, including uveal melanoma, malignant pleural mesothelioma, clear cell renal cell carcinoma, intrahepatic cholangiocarcinoma, hepatocellular carcinoma, and thymic epithelial tumors. BAP1 mutations are also observed at low frequency in other malignancies including breast, colorectal, pancreatic, and bladder cancers. BAP1 germline mutations are associated with high incidence of mesothelioma, uveal melanoma, and other cancers, defining the "BAP1 cancer syndrome." Interestingly, germline BAP1 mutations constitute an important paradigm for gene-environment interactions, as loss of BAP1 predisposes to carcinogen-induced tumorigenesis. Inactivating mutations of BAP1 are also identified in sporadic cancers, denoting the importance of this gene for normal tissue homeostasis and tumor suppression, although some oncogenic properties have also been attributed to BAP1. BAP1 belongs to the deubiquitinase superfamily of enzymes, which are responsible for the maturation and turnover of ubiquitin as well as the reversal of substrate ubiquitination, thus regulating ubiquitin signaling. BAP1 is predominantly nuclear and interacts with several chromatin-associated factors, assembling multi-protein complexes with mutually exclusive partners. BAP1 exerts its function through highly regulated deubiquitination of its substrates. As such, BAP1 orchestrates chromatin-associated processes including gene expression, DNA replication, and DNA repair. BAP1 also exerts cytoplasmic functions, notably in regulating Ca signaling at the endoplasmic reticulum. This DUB is also subjected to multiple post-translational modifications, notably phosphorylation and ubiquitination, indicating that several signaling pathways tightly regulate its function. Recent progress indicated that BAP1 plays essential roles in multiple cellular processes including cell proliferation and differentiation, cell metabolism, as well as cell survival and death. In this review, we summarize the biological and molecular functions of BAP1 and explain how the inactivation of this DUB might cause human cancers. We also highlight some of the unresolved questions and suggest potential new directions.
Topics: Animals; Cell Death; Cell Proliferation; Gene-Environment Interaction; Germ-Line Mutation; Humans; Neoplasms; Protein Processing, Post-Translational; Tumor Suppressor Proteins; Ubiquitin Thiolesterase
PubMed: 33462414
DOI: 10.1038/s41418-020-00709-4 -
Redox Biology Sep 2022Ferroptosis is a newly recognized form of regulated cell death that is characterized by severe lipid peroxidation initiated by iron overload and the generation of...
Ferroptosis is a newly recognized form of regulated cell death that is characterized by severe lipid peroxidation initiated by iron overload and the generation of reactive oxygen species (ROS). However, the role of iron in ionizing radiation (IR)-induced intestinal injury has not been fully illustrated yet. In this study, we found that IR induced ferroptosis in intestinal epithelial cells, as indicated by the increase in intracellular iron levels and lipid peroxidation, upregulation of prostaglandin-endoperoxide synthase 2 (PTGS2) mRNA, reduced glutathione peroxidase 4 (GPX4) mRNA and glutathione (GSH) levels, and significant mitochondrial damage. In addition, the iron chelator deferoxamine (DFO) attenuated IR-induced ferroptosis and intestinal injury in vitro and in vivo. Intriguingly, pharmacological inhibition of autophagy with 3-methyladenine (3-MA) mitigated IR-induced ferritin downregulation, iron overload and ferroptosis. IR increased the levels of nuclear receptor coactivator 4 (NCOA4) mRNA and protein. NCOA4 knockdown significantly inhibited the reduction of ferritin, decreased the level of intracellular free iron, and mitigated ferroptosis induced by IR in HIEC cells, indicating that NCOA4-mediated autophagic degradation of ferritin (ferritinophagy) was required for IR-induced ferroptosis. Furthermore, cytoplasmic iron further activated mitoferrin2 (Mfrn2) on the mitochondrial membrane, which in turn increased iron transport into the mitochondria, resulting in increased ROS production and ferroptosis. In addition, mice fed with an iron-deficient diet for 3 weeks showed a significant reversal in the intestinal injury induced by abdominal IR exposure. Taken together, ferroptosis is a novel mechanism of IR-induced intestinal epithelial cytotoxicity, and is dependent on NCOA4-mediated ferritinophagy.
PubMed: 35932693
DOI: 10.1016/j.redox.2022.102413 -
International Journal of Molecular... Oct 2021Until recently, radiation effects have been considered to be mainly due to nuclear DNA damage and their management by repair mechanisms. However, molecular biology... (Review)
Review
Until recently, radiation effects have been considered to be mainly due to nuclear DNA damage and their management by repair mechanisms. However, molecular biology studies reveal that the outcomes of exposures to ionizing radiation (IR) highly depend on activation and regulation through other molecular components of organelles that determine cell survival and proliferation capacities. As typical epigenetic-regulated organelles and central power stations of cells, mitochondria play an important pivotal role in those responses. They direct cellular metabolism, energy supply and homeostasis as well as radiation-induced signaling, cell death, and immunological responses. This review is focused on how energy, dose and quality of IR affect mitochondria-dependent epigenetic and functional control at the cellular and tissue level. Low-dose radiation effects on mitochondria appear to be associated with epigenetic and non-targeted effects involved in genomic instability and adaptive responses, whereas high-dose radiation effects (>1 Gy) concern therapeutic effects of radiation and long-term outcomes involving mitochondria-mediated innate and adaptive immune responses. Both effects depend on radiation quality. For example, the increased efficacy of high linear energy transfer particle radiotherapy, e.g., C-ion radiotherapy, relies on the reduction of anastasis, enhanced mitochondria-mediated apoptosis and immunogenic (antitumor) responses.
Topics: Epigenesis, Genetic; Epithelial-Mesenchymal Transition; Genomic Instability; Humans; Mitochondria; Mitochondrial Dynamics; Oxidative Stress; Radiation, Ionizing; Reactive Oxygen Species; Signal Transduction
PubMed: 34681703
DOI: 10.3390/ijms222011047 -
International Journal of Molecular... Nov 2020The terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay detects DNA breakage by labeling the free 3'-hydroxyl termini. Given that genomic... (Review)
Review
The terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay detects DNA breakage by labeling the free 3'-hydroxyl termini. Given that genomic DNA breaks arise during early and late stages of apoptosis, TUNEL staining continues to be widely used as a measure of apoptotic cell death. The advantages of the assay include its relative ease of performance and the broad availability of TUNEL assay kits for various applications, such as single-cell analysis of apoptosis in cell cultures and tissue samples. However, as briefly discussed herein, aside from some concerns relating to the specificity of the TUNEL assay itself, it was demonstrated some twenty years ago that the early stages of apoptosis, detected by TUNEL, can be reversed. More recently, compelling evidence from different biological systems has revealed that cells can recover from even late stage apoptosis through a process called anastasis. Specifically, such recovery has been observed in cells exhibiting caspase activation, genomic DNA breakage, phosphatidylserine externalization, and formation of apoptotic bodies. Furthermore, there is solid evidence demonstrating that apoptotic cells can promote neighboring tumor cell repopulation (e.g., through caspase-3-mediated secretion of prostaglandin E) and confer resistance to anticancer therapy. Accordingly, caution should be exercised in the interpretation of results obtained by the TUNEL and other apoptosis assays (e.g., caspase activation) in terms of apoptotic cell demise.
Topics: Animals; Antineoplastic Agents; Apoptosis; Biological Assay; DNA Breaks; Humans; In Situ Nick-End Labeling; Neoplasms
PubMed: 33260475
DOI: 10.3390/ijms21239090 -
Cell Reports May 2022The MDM2 oncoprotein antagonizes the tumor suppressor p53 by physical interaction and ubiquitination. However, it also sustains the progression of DNA replication forks,...
The MDM2 oncoprotein antagonizes the tumor suppressor p53 by physical interaction and ubiquitination. However, it also sustains the progression of DNA replication forks, even in the absence of functional p53. Here, we show that MDM2 binds, inhibits, ubiquitinates, and destabilizes poly(ADP-ribose) polymerase 1 (PARP1). When cellular MDM2 levels are increased, this leads to accelerated progression of DNA replication forks, much like pharmacological inhibition of PARP1. Conversely, overexpressed PARP1 restores normal fork progression despite elevated MDM2. Strikingly, MDM2 profoundly reduces the frequency of fork reversal, revealed as four-way junctions through electron microscopy. Depletion of RECQ1 or the primase/polymerase (PRIMPOL) reverses the MDM2-mediated acceleration of the nascent DNA elongation rate. MDM2 also increases the occurrence of micronuclei, and it exacerbates camptothecin-induced cell death. In conclusion, high MDM2 levels phenocopy PARP inhibition in modulation of fork restart, representing a potential vulnerability of cancer cells.
Topics: DNA; DNA Damage; DNA Primase; DNA Replication; Tumor Suppressor Protein p53
PubMed: 35649362
DOI: 10.1016/j.celrep.2022.110879 -
Diabetologia Oct 2023Glucagon-like peptide-1 receptor agonists (GLP-1RAs, incretin mimetics) and dipeptidyl peptidase-4 inhibitors (DPP-4is, incretin enhancers) are glucose-lowering... (Review)
Review
Glucagon-like peptide-1 receptor agonists (GLP-1RAs, incretin mimetics) and dipeptidyl peptidase-4 inhibitors (DPP-4is, incretin enhancers) are glucose-lowering therapies with proven cardiovascular safety, but their effect on microvascular disease is not fully understood. Both therapies increase GLP-1 receptor agonism, which is associated with attenuation of numerous pathological processes that may lead to microvascular benefits, including decreased reactive oxygen species (ROS) production, decreased inflammation and improved vascular function. DPP-4is also increase stromal cell-derived factor-1 (SDF-1), which is associated with neovascularisation and tissue repair. Rodent studies demonstrate several benefits of these agents in the prevention or reversal of nephropathy, retinopathy and neuropathy, but evidence from human populations is less clear. For nephropathy risk in human clinical trials, meta-analyses demonstrate that GLP-1RAs reduce the risk of a composite renal outcome (doubling of serum creatinine, eGFR reduction of 30%, end-stage renal disease or renal death), whereas the benefits of DPP-4is appear to be limited to reductions in the risk of albuminuria. The relationship between GLP-1RAs and retinopathy is less clear. Many large trials and meta-analyses show no effect, but an observed increase in the risk of retinopathy complications with semaglutide therapy (a GLP-1RA) in the SUSTAIN-6 trial warrants caution, particularly in individuals with baseline retinopathy. Similarly, DPP-4is are associated with increased retinopathy risk in both trials and meta-analysis. The association between GLP-1RAs and peripheral neuropathy is unclear due to little trial evidence. For DPP-4is, one trial and several observational studies show a reduced risk of peripheral neuropathy, with others reporting no effect. Evidence in other less-established microvascular outcomes, such as microvascular angina, cerebral small vessel disease, skeletal muscle microvascular disease and autonomic neuropathies (e.g. cardiac autonomic neuropathy, gastroparesis, erectile dysfunction), is sparse. In conclusion, GLP-1RAs are protective against nephropathy, whereas DPP-4is are protective against albuminuria and potentially peripheral neuropathy. Caution is advised with DPP-4is and semaglutide, particularly for patients with background retinopathy, due to increased risk of retinopathy. Well-designed trials powered for microvascular outcomes are needed to clarify associations of incretin therapies and microvascular diseases.
Topics: Humans; Male; Albuminuria; Diabetes Mellitus; Diabetic Retinopathy; Incretins; Kidney Diseases; Peripheral Nervous System Diseases; Retinal Diseases; Vascular Diseases
PubMed: 37597048
DOI: 10.1007/s00125-023-05988-3