Local and Systemic Overexpression of COMP-Ang1 Induces Ang1/Tie2-Related Thrombocytopenia and SDF-1/CXCR4-Dependent Anemia.

While supplemental angiopoietin-1 (Ang1) improves hematopoiesis, excessive Ang1 induces bone marrow (BM) impairment, hematopoietic stem cell (HSC) senescence, and erythropoietic defect. Here, we examined how excessive Ang1 disturbs hematopoiesis and explored whether hematopoietic defects were related to its level using K14-Cre;c-Ang1 and Col2.3-Cre;c-Ang1 transgenic mice that systemically and locally overexpress cartilage oligomeric matrix protein-Ang1, respectively. We also investigated the impacts of Tie2 inhibitor and AMD3100 on hematopoietic development. Transgenic mice exhibited excessive angiogenic phenotypes, but K14-Cre;c-Ang1 mice showed more severe defects in growth and life span with higher presence of Ang1 compared with Col2.3-Cre;c-Ang1 mice. Dissimilar to K14-Cre;c-Ang1 mice, Col2.3-Cre;c-Ang1 mice did not show impaired BM retention or senescence of HSCs, erythropoietic defect, or disruption of the stromal cell-derived factor 1 (SDF-1)/CXCR4 axis. However, these mice exhibited a defect in platelet production depending on the expression of Tie2 and globin transcription factor 1 (GATA-1), but not GATA-2, in megakaryocyte progenitor (MP) cells. Treatment with Tie2 inhibitor recovered GATA-1 expression in MP cells and platelet production without changes in circulating RBC in transgenic mice. Consecutive AMD3100 administration not only induced irrecoverable senescence of HSCs but also suppressed formation of RBC, but not platelets, via correlated decreases in number of erythroblasts and their GATA-1 expression in B6 mice. Our results indicate that genetic overexpression of Ang1 impairs hematopoietic development depending on its level, in which megakaryopoiesis is preferentially impaired via activation of Ang1/Tie2 signaling, whereas erythropoietic defect is orchestrated by HSC senescence, inflammation, and disruption of the SDF-1/CXCR4 axis.

Progressive Keratoconus in a Patient With Severe Pectus Excavatum and a Cartilage Oligomeric Matrix Protein Gene Mutation: A Case Report.

INTRODUCTION: Keratoconus is a progressive ocular disorder associated with numerous systemic diseases, many of which affect the musculoskeletal system. Although the etiology and pathophysiology of the disorder remain elusive, recent studies suggest a significant role of genetic predisposition in the pathogenesis of keratoconus. This case report aims to elucidate a potential genetic association in a patient presenting with keratoconus, severe pectus excavatum, generalized muscular weakness, and skeletal deformities. CASE DESCRIPTION: A 31-year-old Iranian man presented with progressively diminishing vision in both eyes over the years, eventually diagnosed with keratoconus. The patient's history and further examination indicated generalized muscular weakness, skeletal deformities, and severe pectus excavatum with cardiac and large vessel displacement. Whole-exome sequencing identified two heterozygous gene variants: one in the Cartilage Oligomeric Matrix Protein (COMP) gene and another in the Regulating Synaptic Membrane Exocytosis 1 gene. The patient's systemic and ocular symptoms, combined with the gene variants identified, suggested a connective tissue systemic disorder, potentially within the clinical spectrum of COMPopathies. CONCLUSION: This is the first documented case of bilateral progressive keratoconus associated with severe pectus excavatum, generalized musculoskeletal dystrophy, and a COMP gene mutation. It highlights the necessity of continued search into the pathogenic genes of keratoconus, particularly in cases with coexisting systemic manifestations, to further our understanding of the etiology and pathogenesis of this complex disease.

Osteoarthritis as a Systemic Disease Promoted Prostate Cancer In Vivo and In Vitro.

Osteoarthritis (OA) is increasing worldwide, and previous work found that OA increases systemic cartilage oligomeric matrix protein (COMP), which has also been implicated in prostate cancer (PCa). As such, we sought to investigate whether OA augments PCa progression. Cellular proliferation and migration of RM1 murine PCa cells treated with interleukin (IL)-1α, COMP, IL-1α + COMP, or conditioned media from cartilage explants treated with IL-1α (representing OA media) and with inhibitors of COMP were assessed. A validated murine model was used for tumor growth and marker expression analysis. Both proliferation and migration were greater in PCa cells treated with OA media compared to controls (p < 0.001), which was not seen with direct application of the stimulants. Migration and proliferation were not negatively affected when OA media was mixed with downstream and COMP inhibitors compared to controls (p > 0.05 for all). Mice with OA developed tumors 100% of the time, whereas mice without OA only 83.4% (p = 0.478). Tumor weight correlated with OA severity (Pearson correlation = 0.813, p = 0.002). Moreover, tumors from mice with OA demonstrated increased Ki-67 expression compared to controls (mean 24.56% vs. 6.91%, p = 0.004) but no difference in CD31, PSMA, or COMP expression (p > 0.05). OA appears to promote prostate cancer in vitro and in vivo.

Functional characterization of a rare pathogenic variant c.875G > A, p.(Cys292Tyr) in COMP.

BACKGROUND: The protein encoded by the cartilage oligomeric matrix protein (COMP) gene is a noncollagenous extracellular matrix (ECM) protein that is important for chondrocyte formation and growth. Variations in the COMP gene cause pseudoachondroplasia (PSACH), which is mainly characterized by short-limbed dwarfing in the clinic. AIMS: To characterize the function of a rare pathogenic variant in the COMP gene (c.875G > A, p.Cys292Tyr). MATERIALS & METHODS: We performed 3D structural analysis, in vitro expression analysis, and immunofluorescence to characterize the effects of the variant on protein structure, expression, and cellular localization respectively. RESULTS: Variation modeling showed that the interactions between amino acids were changed after the variation, and there were 31 changes in the secondary structure of mutant COMP (MT-COMP). Western blot showed that the intracellular quantity of MT-COMP was higher than the wild-type COMP (WT-COMP). Cellular immunofluorescence results showed that WT-COMP was less abundant and homogenously distributed in cells, while the MT-COMP accumulated in the cytoplasm. DISCUSSION: Herein, we report a variant of COMP in a Chinese family with PSACH. We have shown that the rare missense variant, COMP c.875G > A, previously reported in ClinVar and identified in our patient, results in excessive accumulation of mutant protein in the cytoplasm, and is therefore pathogenic. CONCLUSION: Through in silico and experimental analyses, we provide evidence that COMP c.875G > A is the likely cause of PSACH in a Chinese family.

Endothelin-1 depletion of cartilage oligomeric matrix protein modulates pulmonary artery superoxide and iron metabolism-associated mitochondrial heme biosynthesis.

This study examines if heme biosynthesis-associated iron metabolism is regulated in pulmonary arteries by endothelin-1 (ET1) potentially through modulating cartilage oligomeric matrix protein (COMP) availability. Our studies in organoid-cultured endothelium-rubbed bovine pulmonary arteries (BPAs) observed COMP depletion by siRNA or hypoxia increases NOX2 and superoxide and depletes mitochondrial SOD2. ET1 also increases superoxide in a manner that potentially impairs mitochondrial heme biosynthesis. In this study, organoid culture of BPA with ET1 (10 nM) increases superoxide in the mitochondrial matrix and extramitochondrial regions associated with COMP depletion, and COMP (0.5 µM) inhibited these superoxide increases. As mitochondrial matrix superoxide could impair heme biosynthesis from protoporphyrin IX (PpIX) by decreasing Fe2+ availability and/or ferrochelatase (FECH), we studied ET1, COMP, and COMP siRNA effects on the expression of FECH, transferrin receptor-1 (TfR1, an indicator of iron availability) and soluble guanylate cyclase (sGC, a key heme-dependent protein), and on measurements of PpIX (HPLC) and heme content. ET1 decreased FECH, heme, and sGC, and increased TfR1 and iron. COMP reversed these effects of ET1, and COMP decreased PpIX and increased heme in the absence of ET1. COMP siRNA increased PpIX detection and TfR1 expression and decreased the expression of FECH and sGC. Nitric oxide (spermine NONOate) relaxation of BPA was inhibited by ET1, and this was attenuated by COMP during exposure to ET1. Thus, COMP depletion by ET1 or siRNA modulates pulmonary artery iron metabolism, which results in loss of heme biosynthesis and heme-dependent cGMP mechanisms.

Epigenetic moderators of naltrexone efficacy in reducing heavy drinking in Alcohol Use Disorder: a randomized trial.

Polymorphisms in genes associated with opioid signaling and dopamine reuptake and inactivation may moderate naltrexone efficacy in Alcohol Use Disorder (AUD), but the effects of epigenetic modification of these genes on naltrexone response are largely unexplored. This study tested interactions between methylation in the µ-opioid receptor (OPRM1), dopamine transporter (SLC6A3), and catechol-O-methyltransferase (COMT) genes as predictors of naltrexone effects on heavy drinking in a 16-week randomized, placebo-controlled trial among 145 treatment-seeking AUD patients. OPRM1 methylation interacted with both SLC6A3 and COMT methylation to moderate naltrexone efficacy, such that naltrexone-treated individuals with lower methylation of the OPRM1 promoter and the SLC6A3 promoter (p = 0.006), COMT promoter (p = 0.005), or SLC6A3 3' untranslated region (p = 0.004), relative to placebo and to those with higher OPRM1 and SLC6A3 or COMT methylation, had significantly fewer heavy drinking days. Epigenetic modification of opioid- and dopamine-related genes may represent a novel pharmacoepigenetic predictor of naltrexone efficacy in AUD.

Clinical, Biochemical, Radiological, Genetic and Therapeutic Analysis of Patients with COMP Gene Variants.

Pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia type 1 (MED1) are two rare skeletal disorders caused by cartilage oligomeric matrix protein (COMP) variants. This study aims to analyze the genotype and phenotype of patients with COMP variants. Clinical information for 14 probands was collected; DNA was extracted from blood for COMP variant detection. Clinical manifestations and radiology scoring systems were established to evaluate the severity of each patient's condition. Serum COMP levels in PSACH patients and healthy subjects were measured. Thirty-nine patients were included, along with 12 PSACH probands and two MED1 probands. Disproportionate short stature, waddling gait, early-onset osteoarthritis and skeletal deformities were the most common features. The height Z-score of PSACH patients correlated negatively with age at evaluation (r = - 0.603, p = 0.01) and the clinical manifestation score (r = - 0.556, p = 0.039). Over 50% of the PSACH patients were overweight/obese. The median serum COMP level in PSACH patients was 16.75 ng/ml, which was significantly lower than that in healthy controls (98.53 ng/ml; p < 0.001). The condition of MED1 patients was better than that of PSACH patients. Four novel variants of COMP were detected: c.874T>C, c.1123_1134del, c.1531G>A, and c.1576G>T. Height Z-scores and serum COMP levels were significantly lower in patients carrying mutations located in calmodulin-like domains 6, 7, and 8. As the two phenotypes overlap to different degrees, PSACH and MED1 are suggested to combine to produce "spondyloepiphyseal dysplasia, COMP type". Clinical manifestations and radiology scoring systems, serum COMP levels and genotype are important for evaluating patient condition severity.

Pseudoachondroplasia: Phenotype and genotype in 11 Indian patients.

Pseudoachondroplasia (PSACH) is an autosomal dominant disorder characterized by rhizomelic short-limbed skeletal dysplasia. The primary clinical and radiographic features include disproportionate dwarfism, joint laxity and hyperextensibility, exaggerated lumbar lordosis, and late ossification of the epiphyses. Identification of disease-causing variants in heterozygous state in COMP establishes the molecular diagnosis of PSACH. We examined 11 families with clinical features suggestive of PSACH. In nine families, we used Sanger sequencing of exons 8-19 of COMP (NM_000095.2) and in two families exome sequencing was used for confirming the diagnosis. We identified 10 de novo variants, including five known variants (c.925G>A, c.976G>A, c.1201G>T, c.1417_1419del, and c.1511G>A) and five variants (c.874T>C, c.1201G>C, c.1309G>A, c.1416_1421delCGACAA, and c.1445A>T) which are not reported outside Indian ethnicity. We hereby report the largest series of individuals with molecular diagnosis of PSACH from India and reiterate the well-known genotype-phenotype corelation in PSACH.

Cartilage Oligomeric Matrix Protein, COMP may be a Better Prognostic Marker Than CEACAM5 and Correlates With Colon Cancer Molecular Subtypes, Tumor Aggressiveness and Overall Survival.

BACKGROUND: New tumor biomarkers are needed to improve the management of colon cancer (CC), the second leading cause of cancer-related deaths in the United States. Carcinoembryonic Antigen (CEA), the translated protein of carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) gene, is used as a biomarker for CC. Cartilage Oligomeric Matrix Protein (COMP) is overexpressed in CC compared to normal colon tissues. This study aims to evaluate the expression of COMP by disease stage, consensus molecular subtype (CMS), its impact on disease outcomes, and comparison to CEACAM5. MATERIALS AND METHODS: RNA-seq data from 456 CC The Cancer Genome Atlas samples and 41 matching control samples were analyzed for COMP expression and CEACAM5 expression. We stratified tumor samples by stage (I-IV), subtype (CMS1-CMS4), tumor location, and Kirsten RAt Sarcoma (KRAS) mutant status and three quartiles were established based on COMP expression. Kaplan Meier survival outcomes were evaluated. RESULTS: COMP expression was significantly higher in tumor samples, with elevation of expression occurring in stage I and significantly increasing in stage IV. Increased COMP expression occurs in CMS4 with relatively low expression in CMS3. No significant expression difference was attributed to tumor location and KRAS mutant status. Compared to CEACAM5, COMP was a stronger molecular marker across stages and subtypes. CMS4 was associated with the high COMP expression, and higher levels of COMP were associated with poorer overall survival, disease-specific survival, and tumor progression-free intervals. CMS2 and 3 were associated with low expression and better survival. CONCLUSION: COMP is a potential molecular biomarker for CC and may be superior to CEA as an indicator of CC.

Expression of cartilage oligomeric matrix protein (COMP) associates with capsular invasion in salivary gland pleomorphic adenoma.

BACKGROUND: Accumulating evidence shows that pleomorphic adenoma (PA) exhibits a unique capsular invasion and with a crucial role in recurrence. This study was designed to explore RNA expression profiles in salivary gland PA in an attempt to further analyse genes associate with capsule invasion. METHODS: We evaluated the expression profiles of 4 salivary gland PA patients by RNA-sequencing. The principal functions of the differentially expressed mRNAs (DEGs) were explored using GO and KEGG analysis. Then, RT-qPCR and correlation analyses were performed to verify the candidate DEGs in 59 PA patients, and immunohistochemical examinations were conducted to validate candidate DEGs. Finally, the COMP-related genes were screened using correlation and biological pathway enrichment analysis, and further validated by RT-qPCR. RESULTS: A total of 974 DEGs were significantly upregulated, and 1464 were downregulated (fold change ≥2.0; p < 0.05). Based on GO and KEGG analyses, extracellular matrix organization and the PI3K-Akt signalling pathway might play pivotal roles in the tumorigenesis of PA. 40 DEGs were screened and validated by RT-qPCR, 11 upregulated and 5 downregulated DEGs were consistent with the sequencing results. Cartilage oligomeric matrix protein (COMP) was identified to have a significant correlation with the capsular invasion of PA and expression of COMP in patients with invasive capsular PA was significantly stronger than PA. Finally, further results could reveal that 5 highest scoring genes were screened as hub genes for COMP. CONCLUSIONS: These findings suggested that COMP may be a prognostic target for PA and might contribute to its capsular invasion.

Cartilage Oligomeric Matrix Protein, Diseases, and Therapeutic Opportunities.

Cartilage oligomeric matrix protein (COMP) is an extracellular matrix (ECM) glycoprotein that is critical for collagen assembly and ECM stability. Mutations of COMP cause endoplasmic reticulum stress and chondrocyte apoptosis, resulting in rare skeleton diseases. The bouquet-like structure of COMP allows it to act as a bridging molecule that regulates cellular phenotype and function. COMP is able to interact with many other ECM components and binds directly to a variety of cellular receptors and growth factors. The roles of COMP in other skeleton diseases, such as osteoarthritis, have been implied. As a well-established biochemical marker, COMP indicates cartilage turnover associated with destruction. Recent exciting achievements indicate its involvement in other diseases, such as malignancy, cardiovascular diseases, and tissue fibrosis. Here, we review the basic concepts of COMP and summarize its novel functions in the regulation of signaling events. These findings renew our understanding that COMP has a notable function in cell behavior and disease progression as a signaling regulator. Interestingly, COMP shows distinct functions in different diseases. Targeting COMP in malignancy may withdraw its beneficial effects on the vascular system and induce or aggravate cardiovascular diseases. COMP supplementation is a promising treatment for OA and aortic aneurysms while it may induce tissue fibrosis or cancer metastasis.

Feingold syndrome type 2 in a patient from China.

Feingold syndrome type 2 (FGLDS2, MIM614326) is a genetic congenital malformation syndrome, caused by germline heterozygous deletion of MIR17HG on chromosome 13q31, which is extremely rare worldwide. To date, less than 25 patients have been described in the literature. Here, we report on a 3-year-old girl presented with hip dysplasia, polysyndactyly of the left thumb, brachymesophalangy of the fifth digit, microcephaly, intellectual disability, and growth delay. This is likely to be the first case of Feingold syndrome type 2 ever discovered among Chinese population. Through genetic testing and pedigree analysis, she was identified to have a de novo 4.8-Mb microdeletion at chromosome 13q31.3-q32.1, encompassing MIR17HG, GPC5, and GPC6. Additionally, we detected two common compound heterozygous variants (c.919-2A>G and c.147C>G) in SLC26A4 encoding pendrin protein, as well as a novel heterozygous variant c.985_988del in COMP encoding cartilage oligomeric matrix protein. This case report aims to analyze the microdeletion and the three types of variant detected in the patient, and to explore the association between the genotype and phenotype in patients with Feingold syndrome type 2, which may contribute to further understanding and future diagnosis of this disorder.

Joint Degeneration in a Mouse Model of Pseudoachondroplasia: ER Stress, Inflammation, and Block of Autophagy.

Pseudoachondroplasia (PSACH), a short limb skeletal dysplasia associated with premature joint degeneration, is caused by misfolding mutations in cartilage oligomeric matrix protein (COMP). Here, we define mutant-COMP-induced stress mechanisms that occur in articular chondrocytes of MT-COMP mice, a murine model of PSACH. The accumulation of mutant-COMP in the ER occurred early in MT-COMP articular chondrocytes and stimulated inflammation (TNFα) at 4 weeks, and articular chondrocyte death increased at 8 weeks while ER stress through CHOP was elevated by 12 weeks. Importantly, blockage of autophagy (pS6), the major mechanism that clears the ER, sustained cellular stress in MT-COMP articular chondrocytes. Degeneration of MT-COMP articular cartilage was similar to that observed in PSACH and was associated with increased MMPs, a family of degradative enzymes. Moreover, chronic cellular stresses stimulated senescence. Senescence-associated secretory phenotype (SASP) may play a role in generating and propagating a pro-degradative environment in the MT-COMP murine joint. The loss of CHOP or resveratrol treatment from birth preserved joint health in MT-COMP mice. Taken together, these results indicate that ER stress/CHOP signaling and autophagy blockage are central to mutant-COMP joint degeneration, and MT-COMP mice joint health can be preserved by decreasing articular chondrocyte stress. Future joint sparing therapeutics for PSACH may include resveratrol.

Anisotropic Chitosan Scaffolds Generated by Electrostatic Flocking Combined with Alginate Hydrogel Support Chondrogenic Differentiation.

The replacement of damaged or degenerated articular cartilage tissue remains a challenge, as this non-vascularized tissue has a very limited self-healing capacity. Therefore, tissue engineering (TE) of cartilage is a promising treatment option. Although significant progress has been made in recent years, there is still a lack of scaffolds that ensure the formation of functional cartilage tissue while meeting the mechanical requirements for chondrogenic TE. In this article, we report the application of flock technology, a common process in the modern textile industry, to produce flock scaffolds made of chitosan (a biodegradable and biocompatible biopolymer) for chondrogenic TE. By combining an alginate hydrogel with a chitosan flock scaffold (CFS+ALG), a fiber-reinforced hydrogel with anisotropic properties was developed to support chondrogenic differentiation of embedded human chondrocytes. Pure alginate hydrogels (ALG) and pure chitosan flock scaffolds (CFS) were studied as controls. Morphology of primary human chondrocytes analyzed by cLSM and SEM showed a round, chondrogenic phenotype in CFS+ALG and ALG after 21 days of differentiation, whereas chondrocytes on CFS formed spheroids. The compressive strength of CFS+ALG was higher than the compressive strength of ALG and CFS alone. Chondrocytes embedded in CFS+ALG showed gene expression of chondrogenic markers (COL II, COMP, ACAN), the highest collagen II/I ratio, and production of the typical extracellular matrix such as sGAG and collagen II. The combination of alginate hydrogel with chitosan flock scaffolds resulted in a scaffold with anisotropic structure, good mechanical properties, elasticity, and porosity that supported chondrogenic differentiation of inserted human chondrocytes and expression of chondrogenic markers and typical extracellular matrix.

Novel mTORC1 Mechanism Suggests Therapeutic Targets for COMPopathies.

Cartilage oligomeric matrix protein (COMP) is a large, multifunctional extracellular protein that, when mutated, is retained in the rough endoplasmic reticulum (ER). This retention elicits ER stress, inflammation, and oxidative stress, resulting in dysfunction and death of growth plate chondrocytes. While identifying the cellular pathologic mechanisms underlying the murine mutant (MT)-COMP model of pseudoachondroplasia, increased midline-1 (MID1) expression and mammalian target of rapamycin complex 1 (mTORC1) signaling was found. This novel role for MID1/mTORC1 signaling was investigated since treatments shown to repress the pathology also reduced Mid1/mTORC1. Although ER stress-inducing drugs or tumor necrosis factor α (TNFα) in rat chondrosarcoma cells increased Mid1, oxidative stress did not, establishing that ER stress- or TNFα-driven inflammation alone is sufficient to elevate MID1 expression. Since MID1 ubiquitinates protein phosphatase 2A (PP2A), a negative regulator of mTORC1, PP2A was evaluated in MT-COMP growth plate chondrocytes. PP2A was decreased, indicating de-repression of mTORC1 signaling. Rapamycin treatment in MT-COMP mice reduced mTORC1 signaling and intracellular retention of COMP, and increased proliferation, but did not change inflammatory markers IL-16 and eosinophil peroxidase. Lastly, mRNA from tuberous sclerosis-1/2-null mice brain tissue exhibiting ER stress had increased Mid1 expression, confirming the relationship between ER stress and MID1/mTORC1 signaling. These findings suggest a mechanistic link between ER stress and MID1/mTORC1 signaling that has implications extending to other conditions involving ER stress.

A novel COMP mutation in a Chinese family with multiple epiphyseal dysplasia.

BACKGROUND: Multiple epiphyseal dysplasia (MED) is a skeletal disorder characterized by delayed and irregular ossification of the epiphyses and early-onset osteoarthritis. At least 66% of the reported autosomal dominant MED (AD-MED) cases are caused by COMP mutations. METHODS: We recruited a four-generation Chinese family with early-onset hip osteoarthritis, flatfoot, brachydactyly, and mild short stature. An assessment of the family history, detailed physical examinations, and radiographic evaluations were performed on the proband and other family members, followed by the performance of whole-exome sequencing (WES). The pathogenicity of the candidate mutation was also analyzed. RESULTS: An AD-MED family with 10 affected members and 17 unaffected members was recruited. The main radiographic findings were symmetrical changes in the dysplastic acetabulum and femoral heads, irregular contours of the epiphyses, a shortened femoral neck, and flatfoot. Lower bone density was also observed in the ankle joints, wrist joints, and knees, as well as irregular vertebral end plates. In the proband, we identified the missense mutation c.1153G > T (p. Asp385Tyr), located in exon 11 of the COMP gene. This mutation was assessed as 'pathogenic' because of its low allele frequency and its high likelihood of co-segregation with disease in the reported family. Sanger sequencing validated the novel heterozygous mutation c.1153G > T (p. Asp385Tyr) in exon 11 of COMP in all affected individuals in the family. CONCLUSIONS: Our results underlined a key role of the Asp385 amino acid in the protein function of COMP and confirmed the pathogenicity of the COMP (c.1153G > T; p. Asp385Tyr) mutation in AD-MED disease. We have therefore expanded the known mutational spectrum of COMP and revealed new phenotypic information for AD-MED.

Cartilage oligomeric matrix protein (COMP) promotes cell proliferation in early-onset colon cancer tumorigenesis.

BACKGROUND: Colon cancer (CC) is the third most commonly diagnosed cancer in the USA. While the overall incidence is declining, it is rising alarmingly in young patients (EOCC). CC in young patients tends to be more aggressive and often diagnosed at more advanced stages and portend poorer prognosis. Our recently published data showed that EOCC is a distinct disease with unique molecular features compared to late-onset CC (LOCC). The Cartilage Oligomeric Matrix Protein (COMP) was shown to be significantly upregulated in EOCC and correlated with poor survival. However, the role of COMP in CC tumorigenesis, especially in young patients, is not well understood. Thus, the aim of this study was to elucidate the role of COMP in CC tumorigenesis by modulating COMP levels in vitro and test how it affects proliferation. Then, patient samples were evaluated by testing the levels of proliferation marker Ki67. In addition, this study investigates whether higher transcriptional mRNA levels of COMP seen in more aggressive early-onset CC correlate with protein levels compared to late-onset CC. METHODS: COMP mRNA levels in fresh frozen colon tumors (young: n = 5; old: n = 5) were assessed by quantitative PCR (qPCR). Additionally, CC cell lines were profiled for COMP expression to choose an in vitro model to study the role of COMP in CC tumorigenesis. HT-29 (low COMP expression) and CaCo-2 (high COMP expression) cells were used for in vitro proliferation studies. Immunohistochemical (IHC) analysis was conducted to assess COMP and Ki67 protein levels in formalin-fixed paraffin-embedded (FFPE) colon tumors. RESULTS: Significantly higher COMP expression levels were observed in fresh frozen EOCC compared to LOCC tumors. This observation confirmed our previously reported results from NanoString gene expression assay using FFPE samples. Cell proliferation was significantly increased in HT-29 and CaCo-2 cells upon treatment with human recombinant COMP protein after 48 and 72 h (P < 0.05). This increase was more profound in HT-29 cells. Staining for COMP and Ki67 revealed high COMP protein levels in EOCC compared to LOCC patients. CONCLUSION: COMP mRNA and protein levels are significantly higher in EOCC patients. Higher COMP levels correlate with increased proliferation suggesting a role in CC tumorigenesis.

[Expression of cartilage oligomeric matrix protein in the synovial chondromatosis of the temporomandibular joint].

OBJECTIVE: To detect the expression of cartilage oligomeric matrix protein (COMP) in the synovial chondromatosis of the temporomandibular joint (TMJSC), and to discuss the possible interactions between COMP, transforming growth factor (TGF)-ß3, TGF-ß1 and bone morphogenetic protein-2 (BMP-2) in the development of this neoplastic disease. METHODS: Patients in Peking University School and Hospital of Stomatology from January 2011 to February 2020 were selected, who had complete medical records, TMJSC was verified histologically after operation. The expressions of COMP, TGF-ß3, TGF-ß1 and BMP-2 in the TMJSC of the temporomandibular joint were detected by immunohistochemistry and quantitative real-time PCR (RT-PCR) at the protein level and mRNA level respectively, compared with the normal synovial tissue of temporomandibular joint. The histological morphology, protein expression and distribution of TMJSC tissues were observed microscopically, and the positive staining proteins were counted and scored. SPSS 22.0 statistical software was used to analyze the expression differences between the related proteins in TMJSC tissue and the normal synovial tissue of temporomandibular joint and to compare their differences. P < 0.05 indicated that the difference was statistically significant. RESULTS: Immunohistochemical results showed that the positive expression of COMP in TMJSC tissues was mostly found in synovial tissues and chondrocytes adjacent to synovial tissues, and the difference was statistically significant, compared with the normal temporomandibular joint synovial tissues. The positive expression of COMP was significantly different between recurrent TMJSC and non-recurrent ones. The positive expressions of TGF-ß3, TGF-ß1 and BMP-2 were higher than the normal synovial tissue, and were also mostly found in the synovial cells and adjacent chondrocytes, which was further confirmed by Western blot. According to the RT-PCR results, the expressions of COMP, TGF-ß3, TGF-ß1 and BMP-2 in TMJSC were higher than those in the normal synovial tissue. CONCLUSION: The expression of COMP in TMJSC of temporomandibular joint increased significantly, compared with the normal synovial tissue. There may be interactions between COMP and cytokines related to the proliferation and differentiation, like TGF-ß3, TGF-ß1 and BMP-2, which may play a potential role in the pathogenesis of TMJSC.

Age Dependent Progression of Multiple Epiphyseal Dysplasia and Pseudoachondroplasia Due to Heterozygous Mutations in COMP Gene.

Dominantly inherited mutations in COMP gene encoding cartilage oligomeric matrix protein may cause two dwarfing skeletal dysplasias, milder multiple epiphyseal dysplasia (MED) and more severe pseudoachondroplasia (PSACH). We studied the phenotype and X-rays of 11 patients from 5 unrelated families with different COMP mutations. Whole exome and/or Sangers sequencing were used for molecular analyses. Four to ten X-ray images of hands hips, knees or spine were available for each patient for retrospective analyses. Eight patients with MED have mutation c.1220G>A and 3 children with PSACH mutations c.1359C>A, c.1336G>A, or the novel mutation c.1126G>T in COMP. Progressive failure in growth developed in all patients from early childhood and resulted in short stature < 3rd percentile in 7 patients and very short stature < 1st percentile in four. Most patients had joint pain since childhood, severe stiffness in shoulders and elbows but increased mobility in wrists. Six children had bowlegs and two had knock knees. In all patients, X-rays of hands, hips and knees showed progressive, age-dependent skeletal involvement more pronounced in the epiphyses of long rather than short tubular bones. Anterior elongation and biconvex configuration of vertebral bodies were more conspicuous for kids. Six children had correction of knees and two adults had hip replacement. Skeletal and joint impairment in patients with MED and PSACH due to COMP mutation start in early childhood. Although the clinical severity is mutation and age dependent, many symptoms represent a continuous phenotypic spectrum between both diseases. Most patients may benefit from orthopaedic surgeries.

Wnt and RUNX2 mediate cartilage breakdown by osteoarthritis synovial fibroblast-derived ADAMTS-7 and -12.

Failure of therapeutic approaches for the treatment of osteoarthritis (OA) based on the inhibition of metalloproteinases, might be because of their constitutive expression in homeostasis, together with their network complexity. The knowledge of this network would contribute to selective target pathological conditions. In this sense, blockade of mediators produced by neighbouring joint cells, such as synovial fibroblasts (SF), would prevent cartilage damage. Thus, we studied the contribution of ADAMTS-7 and -12 from SF to cartilage oligomeric matrix protein (COMP) degradation, and the signalling pathways involved in their expression. We report for the first time in SF, the involvement of ERK-Runx2 axis and Wnt/ß-catenin signalling in ADAMTS-12 and ADAMTS-7 expressions, respectively, with the subsequent consequences in COMP degradation from cartilage extracellular matrix. After stimulation with IL-1ß or fibronectin fragments, we showed that ERK inhibition decreased Runx2 activation and ADAMTS-12 expression in OA-SF, also reducing Fn-fs-induced COMP degradation. Blockage of Wnt signalling by DKK1 reduced ADAMTS-7 and COMP degradation in OA-SF as well. In addition, Wnt7B expression was induced by IL-1ß and by itself, also increasing ADAMTS-7. Our results could contribute to the development of disease-modifying OA drugs targeting ADAMTS-7 and -12 for the prevention of extracellular matrix components degradation like COMP.