Adenosine Methylation Level of miR-125a-5p Promotes Anti-PD-1 Therapy Escape through the Regulation of IGSF11/VSIG3 Expression

Background: Despite encouraging anti-tumour activity in lung cancer, anti-PD-1 therapy has encountered increasing resistance to treatment. Several companion diagnostic assays have been performed to identify patients who may benefit from this immunotherapy and to adapt this therapy in case of acquired resistance. Methods: A large panel of methods was used for the analysis of expression and methylation levels of miRNAs (qPCR, MemiRIP, …), protein/miRNA interactions (CLIP, oligo pull-down, …), and protein–protein interactions (CoIP) in cells and/or blood samples. Results: Our work highlights that the saturation of PD-1 by anti-PD1 therapies induces an immune escape phenomenon due to the overexpression of IGSF11 following adenosine methylation of miR-125a-5p. Mechanistically, we identify METTL3/KHDRBS3 and HuR as two crucial players in the methylation and the loss of the repressive function of this miRNA. Finally, our work shows that the adenosine methylation of miR-125a-5p is analyzable from EVs/exosomes from longitudinal blood samples and that such EVs/exosomes modulate the IGSF11/VSIG3 expression in lung cancer cells to promote an immune escape phenomenon. Conclusions: Our data provide a biomarker (m6A-miR-125a-5p level) and two therapeutic solutions (anti-IGSF11 antibody and METTL3 inhibitor) that could potentially address the anti-PD1 therapy failure in the context of precision and personalized medicine

TOM20-mediated transfer of Bcl2 from ER to MAM and mitochondria upon induction of apoptosis

International audienceIn this work, we have explored the subcellular localization of Bcl2, a major antiapoptotic protein. In U251 glioma cells, we found that Bcl2 is localized mainly in the ER and is translocated to MAM and mitochondria upon induction of apoptosis; this mitochondrial transfer was not restricted to the demonstrator cell line, even if cell-specific modulations exist. We found that the Bcl2/mitochondria interaction is controlled by TOM20, a protein that belongs to the protein import machinery of the mitochondrial outer membrane. The expression of a small domain of interaction of TOM20 with Bcl2 potentiates its anti-apoptotic properties, which suggests that the Bcl2-TOM20 interaction is proapoptotic. The role of MAM and TOM20 in Bcl2 apoptotic mitochondrial localization and function has been confirmed in a yeast model in which the ER-mitochondria encounter structure (ERMES) complex (required for MAM stability in yeast) has been disrupted. Bcl2-TOM20 interaction is thus an additional player in the control of apoptosis

Paraoxonase 1 (PON1) as a marker of short term death in breast cancer recurrence

International audienceObjective: To relate paraoxonase (PON1) activity to survival time and short term death in breast cancer recurrence. Design and methods: PON1 activity was measured by its rate of hydrolysis of two different substrates, paraoxon (PON) and phenylacetate (ARE) in 50 patients with recurrence of breast cancer. Results were compared between patients surviving more than one year after the analysis (22) and those who died within one year (28). Results: In a logistic regression analysis, ARE was negatively associated with early death (OR=0.10 [0.02-0.58], p=0.0109). PON did not reach significance (OR=0.43 [0.17-1.11], p=0.0826). In a multiple logistic regression analysis model, ARE was independently associated with early death (OR=0.12 [0.02-0.98], p=0.0476), besides interval time between diagnosis and recurrence (OR=0.54 [0.27-1.07], p=0.0781) and undernutrition (OR=3.95 [0.81-19.19], p=0.0883). Conclusion: Paraoxonase is a potential marker of survival in patients with breast cancer recurrence. (C) 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved

Diuron modulates the DNA methylation status of the ILT7 and TRAIL/TNFSF10 genes and decreases the killing activity of plasmacytoid dendritic cells

International audienceBackground: Plasmacytoid dendritic cell (pDC) is described as the Swiss knife of immune system. Thus, the understanding of aberrant epigenetic reprogramming of genes governing the pDC functionality by pollutants appears such as an attractive research point. Results: Our study has investigated the effect of Diuron (an herbicide) on the pDC-killing activity towards cancer cells. Thus, we observed that the Diuron exposure of pDC promotes a context of global DNA hypomethylation, which is associated with a phenotype of decrease of the killing activity of pDC towards cancer cells. At molecular level, our data associated the Diuron-induced global DNA hypomethylation with the elevated expression of TET2, an epigenetic player involved in DNA demethylation processes, and the decrease of the pDC-killing activity with the decrease of TRAIL expression and the increase of ILT7 expression. Conclusions: Thus, our article reports that a pollutant (Diuron) induces an epigenetic reprogramming of a subtype of immune cell (pDC), which decreases its killing activity towards tumors cells. In some context, this mechanism might be conducive to the initiation of pathologies. which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made

Sensitization of EGFR wild-type non-small cell lung cancer cells to EGFR-tyrosine kinase inhibitor erlotinib.: wtEGFR non-small cell lung cancer sensitization to erlotinib

International audienceThe benefit of EGFR-TKI in non-small cell lung cancer has been demonstrated in mutant EGFR tumors as first-line treatment but the benefit in wild-type EGFR tumors is marginal as well as restricted to maintenance therapy in pretreated patients. This work aimed at questioning the effects of cisplatin initial treatment on the EGFR pathway in non-small cell lung cancer and the functional consequences in vitro and in in vivo animal models of Patient-Derived Xenografts (PDX). We establish here that cisplatin pretreatment specifically sensitizes wild-type EGFR expressing cells to erlotinib, contrary to what happens in mutant-EGFR cells and with a blocking EGFR antibody, both in vitro and in vivo. The sensitization entails the activation of the kinase Src upstream of EGFR, thereafter transactivating EGFR through a ligand-independent activation. We propose a combination of markers which enable to discriminate between the tumors sensitized to erlotinib or not in PDX models, that should be worth testing in patients. These markers might be useful for the selection of patients who would benefit from erlotinib as a maintenance therapy

Sphingolipids distribution at mitochondria-associated membranes (MAM) upon induction of apoptosis.

International audienceThe levels and composition of sphingolipids and related metabolites are altered in aging and common disorders such as diabetes and cancers, as well as in neurodegenerative, cardiovascular, and respiratory diseases. Changes in sphingolipids have been implicated as being an essential step in mitochondria-driven cell death. However, little is known about the precise sphingolipid composition and modulation in mitochondria or related organelles. Here, we used LC-MS/MS to analyze the presence of key components of the ceramide metabolic pathway in vivo and in vitro in purified endoplasmic reticulum (ER), mitochondria-associated membranes (MAM), and mitochondria. Specifically, we analyzed the sphingolipids in the three pathways that generate ceramide: sphinganine in the de novo ceramide pathway, sphingomyelin in the breakdown pathway, and sphingosine in the salvage pathway. We observed sphingolipid profiles in mouse liver, mouse brain, and a human glioma cell line (U251). We analyzed the quantitative and qualitative changes of these sphingolipids during staurosporine (STS)-induced apoptosis in U251 cells. Ceramide, especially C16-ceramide, levels increased during early apoptosis possibly through a conversion from mitochondrial sphinganine and sphingomyelin, but sphingosine and lactosyl- and glucosyl-ceramide levels were unaffected. We also found that ceramide generation is enhanced in mitochondria when sphingomyelin levels are decreased in the MAM. This decrease was associated with an increase in acid sphingomyelinase (ASM) activity in MAM. We conclude that meaningful sphingolipid modifications occur in MAM, the mitochondria, and ER during the early phases of apoptosis

Sensitization of EGFR wild-type non-small cell lung cancer cells to EGFR-tyrosine kinase inhibitor erlotinib.: wtEGFR non-small cell lung cancer sensitization to erlotinib

International audienceThe benefit of EGFR-TKI in non-small cell lung cancer has been demonstrated in mutant EGFR tumors as first-line treatment but the benefit in wild-type EGFR tumors is marginal as well as restricted to maintenance therapy in pretreated patients. This work aimed at questioning the effects of cisplatin initial treatment on the EGFR pathway in non-small cell lung cancer and the functional consequences in vitro and in in vivo animal models of Patient-Derived Xenografts (PDX). We establish here that cisplatin pretreatment specifically sensitizes wild-type EGFR expressing cells to erlotinib, contrary to what happens in mutant-EGFR cells and with a blocking EGFR antibody, both in vitro and in vivo. The sensitization entails the activation of the kinase Src upstream of EGFR, thereafter transactivating EGFR through a ligand-independent activation. We propose a combination of markers which enable to discriminate between the tumors sensitized to erlotinib or not in PDX models, that should be worth testing in patients. These markers might be useful for the selection of patients who would benefit from erlotinib as a maintenance therapy