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Objectives: Alterations in tryptophan (Trp) metabolism have been reported in inflammatory diseases, including rheumatoid arthritis (RA). However, understanding whether these alterations participate in RA development and can be considered putative therapeutic targets remains undetermined.In this study, we combined quantitative Trp metabolomics in the serum from patients with RA and corrective administration of a recombinant enzyme in experimental arthritis to address this question., Methods: Targeted quantitative Trp metabolomics was performed on the serum from 574 previously untreated patients with RA from the ESPOIR (Etude et Suivi des POlyarthrites Indifférenciées Récentes) cohort and 98 healthy subjects. A validation cohort involved 69 established patients with RA. Dosages were also done on the serum of collagen-induced arthritis (CIA) and collagen antibody-induced arthritis (CAIA) mice and controls. A proof-of-concept study evaluating the therapeutic potency of targeting the kynurenine pathway was performed in the CAIA model., Results: Differential analysis revealed dramatic changes in Trp metabolite levels in patients with RA compared with healthy controls. Decreased levels of kynurenic (KYNA) and xanthurenic (XANA) acids and indole derivatives, as well as an increased level of quinolinic acid (QUIN), were found in the serum of patients with RA. They correlated positively with disease severity (assessed by both circulating biomarkers and disease activity scores) and negatively with quality-of-life scores. Similar profiles of kynurenine pathway metabolites were observed in the CAIA and CIA models. From a mechanistic perspective, we demonstrated that QUIN favours human fibroblast-like synoviocyte proliferation and affected their cellular metabolism, through inducing both mitochondrial respiration and glycolysis. Finally, systemic administration of the recombinant enzyme aminoadipate aminotransferase, responsible for the generation of XANA and KYNA, was protective in the CAIA model., Conclusions: Altogether, our preclinical and clinical data indicate that alterations in the Trp metabolism play an active role in the pathogenesis of RA and could be considered as a new therapeutic avenue., Competing Interests: Competing interests: HS reports lecture fee, board membership, or consultancy from Amgen, Fresenius, IPSEN, Actial, Astellas, Danone, THAC, Biose, BiomX, Eligo, Immusmol, Adare, Nestle, Ferring, MSD, Bledina, Pfizer, Biocodex, BMS, Bromatech, Gilead, Janssen, Mayoli, Roche, Sanofi, Servier, Takeda, AbbVie; has stocks from Enterome bioscience; and is co-founder of Exeliom Biosciences. JS reports lecture fee, board membership, or consultancy from AbbVie, MSD, Biogen, Pfizer, BMS, Galapagos, Fresenius Kabi, AstraZeneca, UCB, Chugai, Novartis and Janssen. XM report consultancy for AstraZeneca, BMS, Galapagos, GSK, Novartis and Pfizer. D Mulleman received invitation to attend congress: Celltrion healthcare and GSK., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

The extracellular matrix (ECM) of articular cartilage is a three-dimensional network mainly constituted of entangled collagen fibrils and interfibrillar aggrecan aggregates. During the development of osteoarthritis (OA), the most common musculoskeletal disorder, the ECM is subjected to a combination of chemical and structural changes that play a pivotal role in the initiation and the progress of the disease. While the molecular mechanisms involved in the pathological remodelling of the ECM are considered as decisive, they remain, however, not completely elucidated. Herein, we report a relevant way for unravelling the role and nature of OA progress on human cartilage tissues, in terms of chemical composition and morphological and mechanical properties at the level of supramolecular assemblies constituting the cartilage ECM. For this purpose, we used X-ray photoelectron spectroscopy (XPS), and developed an innovative methodological approach that provides the molecular composition of the ECM. Moreover, we used atomic force microscopy (AFM) to probe the tissues at the level of individual collagen fibrils, both imaging and force spectroscopy modes being explored to this end. Taken together, these nanoscale characterization studies reveal the existence of two stages in the OA progress. At the early stage, a marked increase in the aggrecan and collagen content is observed, reflecting the homeostatic chondrocyte activity that tends to repair the cartilage ECM. At the late stage, we observe a failed attempt to stabilize and/or restore the tissue, yielding significant degradation of the supramolecular assemblies. This suggests an imbalance in the chondrocyte activity that turns in favor of catabolic events. Chemical changes are also accompanied by ECM structural changes and stiffening. Interestingly, we showed the possibility to mimic the imbalanced activities of chondrocytes by applying enzymatic digestions of healthy cartilage, through the combined action of hyaluronidase and collagenase. This yields damage strictly analogous to that observed at high OA severity. These findings bring mechanistic insights leading to a better understanding of the mechanism by which OA is initiated and progresses in the cartilage ECM. They offer guidelines for the development of curative treatments, such as targeting the homeostatic balance of chondrocyte metabolism through the control of enzymatic reactions involved in catabolic processes.

Background: Immune checkpoint (ICK) expression might represent a surrogate measure of tumor-infiltrating T cell (CTL) exhaustion and therefore be a more accurate prognostic biomarker for colorectal cancer (CRC) patients than CTL enumeration as measured by the Immunoscore., Methods: The expression of ICKs, Th1, CTLs, cytotoxicity-related genes, and metagenes, including Immunoscore-like metagenes, were evaluated in three independent cohorts of CRC samples (260 microsatellite instable [MSI], 971 non-MSI). Their associations with patient survival were analyzed by Cox models, taking into account the microsatellite instability (MSI) status and affiliation with various Consensus Molecular Subgroups (CMS). PD-L1 and CD8 expression were examined on a subset of tumors with immunohistochemistry. All statistical tests were two-sided., Results: The expression of Immunoscore-like metagenes was statistically significantly associated with improved outcome in non-MSI tumors displaying low levels of both CTLs and immune checkpoints (ICKs; CMS2 and CMS3; hazard ratio [HR] = 0.63, 95% confidence interval [CI] = 0.43 to 0.92, P = .02; and HR = 0.55, 95% CI = 0.34 to 0.90, P = .02, respectively), but clearly had no prognostic relevance in CRCs displaying higher levels of CTLs and ICKs (CMS1 and CMS4; HR = 0.46, 95% CI = 0.10 to 2.10, P = .32; and HR = 1.13, 95% CI = 0.79 to 1.63, P = .50, respectively), including MSI tumors. ICK metagene expression was statistically significantly associated with worse prognosis independent of tumor staging in MSI tumors (HR = 3.46, 95% CI = 1.41 to 8.49, P = .007). ICK expression had a negative impact on the proliferation of infiltrating CD8 T cells in MSI neoplasms (median = 0.56 in ICK low vs median = 0.34 in ICK high, P = .004)., Conclusions: ICK expression cancels the prognostic relevance of CTLs in highly immunogenic colon tumors and predicts a poor outcome in MSI CRC patients., (© The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com)

Background: Every colorectal cancer (CRC) patient should be tested for microsatellite instability (MSI, a marker for defective DNA mismatch repair) as a first screen for Lynch syndrome (LS). In this study, we investigated whether it may be possible to improve the detection of MSI in CRC. We examined whether the HT17 DNA repeat (critical for correct splicing of the chaperone HSP110) might constitute a superior marker for diagnosis of the MSI phenotype in patients with CRC compared with the standard panel of markers (pentaplex)., Methods: The HT17 polymorphism was analysed in germline DNA from 1037 multi-ethnic individuals. We assessed its sensitivity and specificity for detecting MSI in a multicentre, population-based cohort of 685 patients with CRC and an additional series of 70 patients with CRC considered to be at-risk of LS. All cases were screened earlier for MSI using pentaplex markers. Cases showing discordant HT17/pentaplex results were further examined for the expression of mismatch repair proteins., Results: HT17 status was analysed independently and blinded to previous results from pentaplex genotyping. HT17 showed no germline allelic variation outside a very narrow range. Compared with the pentaplex panel, HT17 showed better sensitivity (0.984 (95% CI 0.968 to 0.995) vs 0.951 (95% CI 0.925 to 0.972)) and similar specificity (0.997 (95% CI 0.989 to 1.000) for both) for the detection of MSI. Furthermore, HT17 alone correctly classified samples judged to be uncertain with the pentaplex panel and showed excellent ability to detect MSI in patients with LS., Conclusions: HT17 simplifies and improves the current standard molecular methods for detecting MSI in CRC., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/)

HSP110 is induced by different stresses and, through its anti-apoptotic and chaperoning properties, helps the cells to survive these adverse situations. In colon cancers, HSP110 is abnormally abundant. We have recently showed that colorectal cancer (CRC) patients with microsatellite instability (MSI) had an improved response to chemotherapy because they harbor an HSP110 inactivating mutation (HSP110DE9). In this work, we have used patients' biopsies and human CRC cells grown in vitro and in vivo (xenografts) to demonstrate that (1) HSP110 is secreted by CRC cells and that the amount of this extracellular HSP110 is strongly decreased by the expression of the mutant HSP110DE9, (2) Supernatants from CRC cells overexpressing HSP110 or purified recombinant human HSP110 (LPS-free) affect macrophage differentiation/polarization by favoring a pro-tumor, anti-inflammatory profile, (3) Conversely, inhibition of HSP110 (expression of siRNA, HSP110DE9 or immunodepletion) induced the formation of macrophages with a cytotoxic, pro-inflammatory profile. (4) Finally, this effect of extracellular HSP110 on macrophages seems to implicate TLR4. These results together with the fact that colorectal tumor biopsies with HSP110 high were infiltrated with macrophages with a pro-tumoral profile while those with HSP110 low were infiltrated with macrophages with a cytotoxic profile, suggest that the effect of extracellular HSP110 function on macrophages may also contribute to the poor outcomes associated with HSP110 expression.

Mismatch-repair (MMR)-deficient cells show increased in vitro tolerance to thiopurines because they escape apoptosis resulting from MMR-dependent signaling of drug-induced DNA damage. Prolonged treatment with immunosuppressants including azathioprine (Aza), a thiopurine prodrug, has been suggested as a risk factor for the development of late onset leukemias/lymphomas displaying a microsatellite instability (MSI) phenotype, the hallmark of a defective MMR system. We performed a dose effect study in mice to investigate the development of MSI lymphomas associated with long term Aza treatment. Over two years, Aza was administered to mice that were wild type, null or heterozygous for the MMR gene Msh2. Ciclosporin A, an immunosuppressant with an MMR-independent signaling, was also administered to Msh2(wt) mice as controls. Survival, lymphoma incidence and MSI tumor phenotype were investigated. Msh2(+/-) mice were found more tolerant than Msh2(wt) mice to the cytotoxicity of Aza. In Msh2(+/-) mice, Aza induced a high incidence of MSI lymphomas in a dose-dependent manner. In Msh2(wt) mice, a substantial lifespan was only observed at the lowest Aza dose. It was associated with the development of lymphomas, one of which displayed the MSI phenotype, unlike the CsA-induced lymphomas. Our findings define Aza as a risk factor for an MSI-driven lymphomagenesis process.

Background & Aims: Patients with colorectal tumors with microsatellite instability (MSI) have better prognoses than patients with tumors without MSI, but have a poor response to 5-fluorouracil–based chemotherapy. A dominant-negative form of heat shock protein (HSP)110 (HSP110DE9) expressed by cancer cells with MSI, via exon skipping caused by somatic deletions in the T(17) intron repeat, sensitizes the cells to 5-fluorouracil and oxaliplatin.We investigated whether HSP110 T(17) could be used to identify patients with colorectal cancer who would benefit from adjuvant chemotherapy with 5-fluorouracil and oxaliplatin., Methods: We characterized the interaction between HSP110 and HSP110DE9 using surface plasmon resonance. By using polymerase chain reaction and fragment analysis, we examined how the size of somatic allelic deletions in HSP110 T(17) affected the HSP110 protein expressed by tumor cells. We screened 329 consecutive patients with stage II–III colorectal tumors with MSI who underwent surgical resection at tertiary medical centers for HSP110 T(17)., Results: HSP110 and HSP110DE9 interacted in a1:1 ratio. Tumor cells with large deletions in T(17) had increased ratios of HSP110DE9:HSP110, owing to the loss of expression of full-length HSP110. Deletions in HSP110 T(17) were mostly biallelic in primary tumor samples with MSI. Patients with stage II–III cancer who received chemotherapy and had large HSP110 T(17) deletions (≥5 bp; 18 of 77 patients, 23.4%) had longer times of relapse-free survival than patients with small or no deletions (≤4 bp; 59 of 77 patients, 76.6%) in multivariate analysis (hazard ratio, 0.16; 95% confidence interval, 0.012–0.8; P = .03). We found a significant interaction between chemotherapy and T17 deletion (P =.009)., Conclusions: About 25% of patients with stages II–III colorectal tumors with MSI have an excellent response to chemotherapy, due to large, biallelic deletions in the T(17) intron repeat of HSP110 in tumor DNA.

Mismatch repair-deficient colorectal cancers (CRC) display widespread instability at DNA microsatellite sequences (MSI). Although MSI has been reported to commonly occur at coding repeats, leading to alterations in the function of a number of genes encoding cancer-related proteins, nothing is known about the putative impact of this process on non-coding microRNAs. In miRbase V15, we identified very few human microRNA genes with mono- or di-nucleotide repeats (n = 27). A mutational analysis of these sequences in a large series of MSI CRC cell lines and primary tumors underscored instability in 15 of the 24 microRNA genes successfully studied at variable frequencies ranging from 2.5% to 100%. Following a maximum likelihood statistical method, microRNA genes were separated into two groups that differed significantly in their mutation frequencies and in their tendency to represent mutations that may or may not be under selective pressures during MSI tumoral progression. The first group included 21 genes that displayed no or few mutations in CRC. The second group contained three genes, i.e., hsa-mir-1273c, hsa-mir-1303 and hsa-mir-567, with frequent (≥ 80%) and sometimes bi-allelic mutations in MSI tumors. For the only one expressed in colonic tissues, hsa-mir-1303, no direct link was found between the presence or not of mono- or bi-allelic alterations and the levels of mature miR expression in MSI cell lines, as determined by sequencing and quantitative PCR respectively. Overall, our results provide evidence that DNA repeats contained in human miRNA genes are relatively rare and preserved from mutations due to MSI in MMR-deficient cancer cells. Functional studies are now required to conclude whether mutated miRNAs, and especially the miR-1303, might have a role in MSI tumorigenesis.

Heat shock proteins (HSPs) are necessary for cancer cell survival. We identified a mutant of HSP110 (HSP110ΔE9) in colorectal cancer showing microsatellite instability (MSI CRC), generated from an aberrantly spliced mRNA and lacking the HSP110 substrate-binding domain. This mutant was expressed at variable levels in almost all MSI CRC cell lines and primary tumors tested. HSP110ΔE9 impaired both the normal cellular localization of HSP110 and its interaction with other HSPs, thus abrogating the chaperone activity and antiapoptotic function of HSP110 in a dominant-negative manner. HSP110ΔE9 overexpression caused the sensitization of cells to anticancer agents such as oxaliplatin and 5-fluorouracil, which are routinely prescribed in the adjuvant treatment of people with CRC. The survival and response to chemotherapy of subjects with MSI CRCs was associated with the tumor expression level of HSP110ΔE9. HSP110 may thus constitute a major determinant for both prognosis and treatment response in CRC.

Secreted phospholipases A2 (sPLA2s) are present in atherosclerotic plaques and are now considered novel attractive therapeutic targets and potential biomarkers as they contribute to the development of atherosclerosis through lipoprotein-dependent and independent mechanisms. We have previously shown that hGX-sPLA2-phospholipolyzed LDL (LDL-X) induces proinflammatory responses in human umbilical endothelial cells (HUVECs); here we explore the molecular mechanisms involved. Global transcriptional gene expression profiling of the response of endothelial cells exposed to either LDL or LDL-X revealed that LDL-X activates multiple distinct cellular pathways including the unfolded protein response (UPR). Mechanistic insight showed that LDL-X activates UPR through calcium depletion of intracellular stores, which in turn disturbs cytoskeleton organization. Treatment of HUVECs and aortic endothelial cells (HAECs) with LDL-X led to activation of all 3 proximal initiators of UPR: eIF-2alpha, IRE1alpha, and ATF6. In parallel, we observed a sustained phosphorylation of the p38 pathway resulting in the phosphorylation of AP-1 downstream targets. This was accompanied by significant production of the proinflammatory cytokines IL-6 and IL-8. Our study demonstrates that phospholipolyzed LDL uses a range of molecular pathways including UPR to initiate endothelial cell perturbation and thus provides an LDL oxidation-independent mechanism for the initiation of vascular inflammation in atherosclerosis.

Gliomas are highly lethal neoplasms that cannot be cured by currently available therapies. Temozolomide is a recently introduced alkylating agent that has yielded a significant benefit in the treatment of high-grade gliomas. However, either de novo or acquired chemoresistance occurs frequently and has been attributed to increased levels of O6-methylguanine-DNA methyltransferase or to the loss of mismatch repair capacity. However, very few gliomas overexpress O6-methylguanine-DNA methyltransferase or are mismatch repair-deficient, suggesting that other mechanisms may be involved in the resistance to temozolomide. The purpose of the present study was to generate temozolomide-resistant variants from a human glioma cell line (SNB-19) and to use large-scale genomic and transcriptional analyses to study the molecular basis of acquired temozolomide resistance. Two independently obtained temozolomide-resistant variants exhibited no cross-resistance to other alkylating agents [1,3-bis(2-chloroethyl)-1-nitrosourea and carboplatin] and shared genetic alterations, such as loss of a 2p region and loss of amplification of chromosome 4 and 16q regions. The karyotypic alterations were compatible with clonal selection of preexistent resistant cells in the parental SNB-19 cell line. Microarray analysis showed that 78 out of 17,000 genes were differentially expressed between parental cells and both temozolomide-resistant variants. None are implicated in known resistance mechanisms, such as DNA repair, whereas interestingly, several genes involved in differentiation were down-regulated. The data suggest that the acquisition of resistance to temozolomide in this model resulted from the selection of less differentiated preexistent resistant cells in the parental tumor.

Low-grade head and neck squamous cell carcinomas without lymph node involvement or distant metastasis (N(0)M(0)) were screened for chromosomal imbalances by comparative genomic hybridization (CGH). pT(1-2) tumors contain a low number of aberrations (average number, 4.3; 15 cases), in contrast to pT(3) tumors (average number, 11.8; 6 cases), and exhibit a specific CGH pattern, affecting three chromosomes: partial or total 3q gain and/or 3p loss (73% of cases), 8q gain (47%), and 11q13 gain (27%). Thus, these changes represent early events in the pathogenesis of low-grade tumors. Cytogenetic exploration of chromosome 3 aberrations in head and neck cell lines suggests that the formation of an isochromosome 3q is one intermediate mechanism leading to 3p losses and/or 3q gains. On the long arm of chromosome 3, most of tumors exhibit low-level gains of large segments, involving systematically the 3q26-qter area, but with two alternative smallest region overlaps at 3q26 and 3q28-qter. We decided to refine the mapping of 3q26-qter gains by using fluorescence in situ hybridization on tumor nuclei, with clones containing two outstanding positional and functional candidate genes, PIK3CA and p63, located respectively at 3q26 and at 3q28. Although PIK3CA or p63 were preferentially gained in few cases (4 of 45), both genes were over-represented in 27 of 45 low-grade N(0)M(0) carcinomas analyzed by CGH or fluorescence in situ hybridization. To evaluate the relative contribution of PIK3CA and p63 in the pathogenesis of head and neck carcinomas displaying a 3q gain, we measured their respective transcription levels in tumors with previously determined gene copy number. DNp63, the predominant p63 transcript, is overexpressed in tumors compared with normal tissues, but its expression level is independent to gene copy number. In contrast, a significant PIK3CA overexpression is associated with increased gene dosage. These results indicate that PIK3CA, contrary to DNp63, may participate to the progression of head and neck tumors consequent to a low-level 3q over-representation. Interestingly, survival analysis using CGH suggested, in accordance with previous data, that 3q26 gain, the locus of PIK3CA, could predict clinical outcome for early disease tumors. This prompts us to pursue 3q26 (or PIK3CA) prognostic evaluation in a larger population of head and neck squamous cell carcinomas.