Blockade of the Lysophosphatidylserine Lipase ABHD12 Potentiates Ferroptosis in Cancer Cells.
Ontology highlight
ABSTRACT:
SUBMITTER: Kathman SG
PROVIDER: S-EPMC7386317 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:ABHD12 metabolizes bioactive lysophospholipids, including lysophosphatidylserine (lyso-PS). Deleterious mutations in human ABHD12 cause the neurological disease PHARC, and ABHD12-/- mice display PHARC-like phenotypes, including hearing loss, along with elevated brain lyso-PS and features of stimulated innate immune cell function. Here, we develop a selective and in vivo-active inhibitor of ABHD12 termed DO264 and show that this compound elevates lyso-PS in mouse brain and primary human macrophages. Unlike ABHD12-/- mice, adult mice treated with DO264 exhibited minimal perturbations in auditory function. On the other hand, both DO264-treated and ABHD12-/- mice displayed heightened immunological responses to lymphocytic choriomeningitis virus (LCMV) clone 13 infection that manifested as severe lung pathology with elevated proinflammatory chemokines. These results reveal similarities and differences in the phenotypic impact of pharmacological versus genetic blockade of ABHD12 and point to a key role for this enzyme in regulating immunostimulatory lipid pathways in vivo.
| S-EPMC6263940 | biostudies-literature
Project description:ABHD12 is a membrane-bound hydrolytic enzyme that acts on the lysophosphatidylserine (lyso-PS) and lysophosphatidylinositol (lyso-PI) classes of immunomodulatory lipids. Human and mouse genetic studies point to a key role for the ABHD12-(lyso)-PS/PI pathway in regulating (neuro)immunological functions in both the central nervous system and periphery. Selective inhibitors of ABHD12 would offer valuable pharmacological probes to complement genetic models of ABHD12-regulated (lyso)-PS/PI metabolism and signaling. Here, we provide a detailed description of the discovery and activity-based protein profiling (ABPP) guided optimization of reversible thiourea inhibitors of ABHD12 that culminated in the identification of DO264 as a potent, selective, and in vivo active ABHD12 inhibitor. We also show that DO264, but not a structurally related inactive control probe (S)-DO271, augments inflammatory cytokine production from human THP-1 macrophage cells. The in vitro and in vivo properties of DO264 designate this compound as a suitable chemical probe for studying the biological functions of ABHD12-(lyso)-PS/PI pathways.
| S-EPMC6583925 | biostudies-literature
Project description:Advances in human genetics are leading to the discovery of new disease-causing mutations at a remarkable rate. Many such mutations, however, occur in genes that encode for proteins of unknown function, which limits our molecular understanding of, and ability to devise treatments for, human disease. Here, we use untargeted metabolomics combined with a genetic mouse model to determine that the poorly characterized serine hydrolase ?/?-hydrolase domain-containing (ABHD)12, mutations in which cause the human neurodegenerative disorder PHARC (polyneuropathy, hearing loss, ataxia, retinosis pigmentosa, and cataract), is a principal lysophosphatidylserine (LPS) lipase in the mammalian brain. ABHD12(-/-) mice display massive increases in a rare set of very long chain LPS lipids that have been previously reported as Toll-like receptor 2 activators. We confirm that recombinant ABHD12 protein exhibits robust LPS lipase activity, which is also substantially reduced in ABHD12(-/-) brain tissue. Notably, elevations in brain LPS lipids in ABHD12(-/-) mice occur early in life (2-6 mo) and are followed by age-dependent increases in microglial activation and auditory and motor defects that resemble the behavioral phenotypes of human PHARC patients. Taken together, our data provide a molecular model for PHARC, where disruption of ABHD12 causes deregulated LPS metabolism and the accumulation of proinflammatory lipids that promote microglial and neurobehavioral abnormalities.
| S-EPMC3557017 | biostudies-literature
Project description:Reactive oxygen species (ROS) are transient, highly reactive intermediates or byproducts produced during oxygen metabolism. However, when innate mechanisms are unable to cope with sequestration of surplus ROS, oxidative stress results, in which excess ROS damage biomolecules. Oxidized phosphatidylserine (PS), a proapoptotic 'eat me' signal, is produced in response to elevated ROS, yet little is known regarding its chemical composition and metabolism. Here, we report a small molecule that generates ROS in different mammalian cells. We used this molecule to detect, characterize and study oxidized PS in mammalian cells. We developed a chemical-genetic screen to identify enzymes that regulate oxidized PS in mammalian cells and found that the lipase ABHD12 hydrolyzes oxidized PS. We validated these findings in different physiological settings including primary peritoneal macrophages and brains from Abhd12-/- mice under inflammatory stress, and in the process, we functionally annotated an enzyme regulating oxidized PS in vivo.
| S-EPMC6420073 | biostudies-literature
Project description:Immune checkpoint blockade has achieved significant therapeutic success for a subset of cancer patients; however, a large portion of cancer patients do not respond. Unresponsive tumors are characterized as being immunologically "cold," indicating that these tumors lack tumor antigen-specific primed cytotoxic T cells. Sitravatinib is a spectrum-selective tyrosine kinase inhibitor targeting TAM (TYRO3, AXL, MerTK) and split tyrosine-kinase domain-containing receptors (VEGFR and PDGFR families and KIT) plus RET and MET, targets that contribute to the immunosuppressive tumor microenvironment. We report that sitravatinib has potent antitumor activity by targeting the tumor microenvironment, resulting in innate and adaptive immune cell changes that augment immune checkpoint blockade. These results suggest that sitravatinib has the potential to combat resistance to immune checkpoint blockade and expand the number of cancer patients that are responsive to immune therapy.
| S-EPMC6238734 | biostudies-literature
Project description:Tumor-infiltrating CD8 T cells were found to frequently express the inhibitory receptor NKG2A, particularly in immune-reactive environments and after therapeutic cancer vaccination. High-dimensional cluster analysis demonstrated that NKG2A marks a unique immune effector subset preferentially co-expressing the tissue-resident CD103 molecule, but not immune checkpoint inhibitors. To examine whether NKG2A represented an adaptive resistance mechanism to cancer vaccination, we blocked the receptor with an antibody and knocked out its ligand Qa-1b, the conserved ortholog of HLA-E, in four mouse tumor models. The impact of therapeutic vaccines was greatly potentiated by disruption of the NKG2A/Qa-1b axis even in a PD-1 refractory mouse model. NKG2A blockade therapy operated through CD8 T cells, but not NK cells. These findings indicate that NKG2A-blocking antibodies might improve clinical responses to therapeutic cancer vaccines.
| S-EPMC6354585 | biostudies-literature
Project description:BackgroundGlucose-6-phospate dehydrogenase (G6PD) is the limiting enzyme of the pentose phosphate pathway (PPP) correlated to cancer progression and drug resistance. We previously showed that G6PD inhibition leads to Endoplasmic Reticulum (ER) stress often associated to autophagy deregulation. The latter can be induced by target-based agents such as Lapatinib, an anti-HER2 tyrosine kinase inhibitor (TKI) largely used in breast cancer treatment.MethodsHere we investigate whether G6PD inhibition causes autophagy alteration, which can potentiate Lapatinib effect on cancer cells. Immunofluorescence and flow cytometry for LC3B and lysosomes tracker were used to study autophagy in cells treated with lapatinib and/or G6PD inhibitors (polydatin). Immunoblots for LC3B and p62 were performed to confirm autophagy flux analyses together with puncta and colocalization studies. We generated a cell line overexpressing G6PD and performed synergism studies on cell growth inhibition induced by Lapatinib and Polydatin using the median effect by Chou-Talay. Synergism studies were additionally validated with apoptosis analysis by annexin V/PI staining in the presence or absence of autophagy blockers.ResultsWe found that the inhibition of G6PD induced endoplasmic reticulum stress, which was responsible for the deregulation of autophagy flux. Indeed, G6PD blockade caused a consistent increase of autophagosomes formation independently from mTOR status. Cells engineered to overexpress G6PD became resilient to autophagy and resistant to lapatinib. On the other hand, G6PD inhibition synergistically increased lapatinib-induced cytotoxic effect on cancer cells, while autophagy blockade abolished this effect. Finally, in silico studies showed a significant correlation between G6PD expression and tumour relapse/resistance in patients.ConclusionsThese results point out that autophagy and PPP are crucial players in TKI resistance, and highlight a peculiar vulnerability of breast cancer cells, where impairment of metabolic pathways and autophagy could be used to reinforce TKI efficacy in cancer treatment.
| S-EPMC6466760 | biostudies-literature
Project description:BackgroundWhile T cell-activating immunotherapies against recurrent head and neck squamous cell carcinoma (HNSCC) have shown impressive results in clinical trials, they are often ineffective in the majority of patients. NK cells are potential targets for immunotherapeutic intervention; however, the setback in monalizumab-based therapy in HNSCC highlights the need for an alternative treatment to enhance their antitumor activity.MethodsSingle-cell RNA sequencing (scRNA-seq) and TCGA HNSCC datasets were used to identify key molecular alterations in NK cells. Representative HPV-positive ( +) and HPV-negative ( -) HNSCC cell lines and orthotopic mouse models were used to validate the bioinformatic findings. Changes in immune cells were examined by flow cytometry and immunofluorescence.ResultsThrough integration of scRNA-seq data with TCGA data, we found that the impact of IL6/IL6R and CCL2/CCR2 signaling pathways on evasion of immune attack by NK cells is more pronounced in the HPV - HNSCC cohort compared to the HPV + HNSCC cohort. In orthotopic mouse models, blocking IL6 with a neutralizing antibody suppressed HPV - but not HPV + tumors, which was accompanied by increased tumor infiltration and proliferation of CD161+ NK cells. Notably, combining the CCR2 chemokine receptor antagonist RS504393 with IL6 blockade resulted in a more pronounced antitumor effect that was associated with more activated intratumoral NK cells in HPV - HNSCC compared to either agent alone.ConclusionsThese findings demonstrate that dual blockade of IL6 and CCR2 pathways effectively enhances the antitumor activity of NK cells in HPV-negative HNSCC, providing a novel strategy for treating this type of cancer.
| S-EPMC10929116 | biostudies-literature
Project description:BACKGROUND:Triple-negative breast cancer (TNBC) is a uniquely aggressive cancer with high rates of relapse due to resistance to chemotherapy. TNBC expresses higher levels of programmed cell death-ligand 1 (PD-L1) compared to other breast cancers, providing the rationale for the recently approved immunotherapy with anti-PD-L1 monoclonal antibodies (mAbs). A huge effort is dedicated to identify actionable biomarkers allowing for combination therapies with immune-checkpoint blockade. Platelet-derived growth factor receptor ? (PDGFR?) is highly expressed in invasive TNBC, both on tumor cells and tumor microenvironment. We recently proved that tumor growth and lung metastases are impaired in mouse models of human TNBC by a high efficacious PDGFR? aptamer. Hence, we aimed at investigating the effectiveness of a novel combination treatment with the PDGFR? aptamer and anti-PD-L1 mAbs in TNBC. METHODS:The targeting ability of the anti-human PDGFR? aptamer toward the murine receptor was verified by streptavidin-biotin assays and confocal microscopy, and its inhibitory function by transwell migration assays. The anti-proliferative effects of the PDGFR? aptamer/anti-PD-L1 mAbs combination was assessed in human MDA-MB-231 and murine 4?T1 TNBC cells, both grown as monolayer or co-cultured with lymphocytes. Tumor cell lysis and cytokines secretion by lymphocytes were analyzed by LDH quantification and ELISA, respectively. Orthotopic 4?T1 xenografts in syngeneic mice were used for dissecting the effect of aptamer/mAb combination on tumor growth, metastasis and lymphocytes infiltration. Ex vivo analyses through immunohistochemistry, RT-qPCR and immunoblotting were performed. RESULTS:We show that the PDGFR? aptamer potentiates the anti-proliferative activity of anti-PD-L1 mAbs on both human and murine TNBC cells, according to its human/mouse cross-reactivity. Further, by binding to activated human and mouse lymphocytes, the aptamer enhances the anti-PD-L1 mAb-induced cytotoxicity of lymphocytes against tumor cells. Importantly, the aptamer heightens the antibody efficacy in inhibiting tumor growth and lung metastases in mice. It acts on both tumor cells, inhibiting Akt and ERK1/2 signaling pathways, and immune populations, increasing intratumoral CD8?+?T cells and reducing FOXP3?+?Treg cells. CONCLUSION:Co-treatment of PDGFR? aptamer with anti-PD-L1 mAbs is a viable strategy, thus providing for the first time an evidence of the efficacy of PDGFR?/PD-L1 co-targeting combination therapy in TNBC.
| S-EPMC7487859 | biostudies-literature
Project description:Hypoxia and nutrient starvation (H/NS) microenvironment, a notable characteristic of pancreatic carcinoma, plays a critical role in cell death resistance and tumor recurrence. However, its role in ferroptosis remains to be classified. Here, we found that H/NS contributed to the pancreatic cancer cell ferroptosis resistance depending on the altered intracellular lipid compositions. Mechanistically, H/NS induced the upregulation of stearoyl-CoA desaturase 1 (SCD1), which promoted monounsaturated fatty acids (MUFAs) synthesis and protected against lipid peroxidation. Surprisingly, SCD1 showed a strong correlation with antiferroptosis gene expression. Moreover, short-hairpin RNA-based knockdown of SCD1 enhanced erastin-induced ferroptosis in vitro under H/NS. Finally, our results demonstrate the synergistic effect of erastin and A939572, a special SCD1 inhibitor, in dictating pancreatic carcinoma subcutaneous ferroptotic death. Taken together, our findings reveal a new role of the H/NS microenvironment against ferroptosis and suggest a potential therapeutic strategy for overcoming ferroptosis resistance in pancreatic cancer cells.
| S-EPMC8032529 | biostudies-literature