Chondroitin Sulfate Proteoglycan 4 (CSPG4) as an Emerging Target for Immunotherapy to Treat Melanoma.

Immunotherapies, including checkpoint inhibitor antibodies, have precipitated significant improvements in clinical outcomes for melanoma. However, approximately half of patients do not benefit from approved treatments. Additionally, apart from Tebentafusp, which is approved for the treatment of uveal melanoma, there is a lack of immunotherapies directly focused on melanoma cells. This is partly due to few available targets, especially those expressed on the cancer cell surface. Chondroitin sulfate proteoglycan 4 (CSPG4) is a cell surface molecule overexpressed in human melanoma, with restricted distribution and low expression in non-malignant tissues and involved in several cancer-promoting and dissemination pathways. Here, we summarize the current understanding of the expression and functional significance of CSPG4 in health and melanoma, and we outline immunotherapeutic strategies. These include monoclonal antibodies, antibody-drug conjugates (ADCs), chimeric-antigen receptor (CAR) T cells, and other strategies such as anti-idiotypic and mimotope vaccines to raise immune responses against CSPG4-expressing melanomas. Several showed promising functions in preclinical models of melanoma, yet few have reached clinical testing, and none are approved for therapeutic use. Obstacles preventing that progress include limited knowledge of CSPG4 function in human cancer and a lack of in vivo models that adequately represent patient immune responses and human melanoma biology. Despite several challenges, immunotherapy directed to CSPG4-expressing melanoma harbors significant potential to transform the treatment landscape.

Shotgun Proteomics Links Proteoglycan-4+ Extracellular Vesicles to Cognitive Protection in Amyotrophic Lateral Sclerosis.

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder lacking reliable biomarkers for early diagnosis and disease progression monitoring. This study aimed to identify the novel biomarkers in plasmatic extracellular vesicles (EVs) isolated from ALS patients and healthy controls (HCs). A total of 61 ALS patients and 30 age-matched HCs were enrolled in the study and the protein content of circulating EVs was analyzed by shotgun proteomics. The study was divided into a discovery phase (involving 12 ALS and 12 HC patients) and a validation one (involving 49 ALS and 20 HC patients). In the discovery phase, more than 300 proteins were identified, with 32 proteins showing differential regulation in ALS patients compared to HCs. In the validation phase, over 400 proteins were identified, with 20 demonstrating differential regulation in ALS patients compared to HCs. Notably, seven proteins were found to be common to both phases, all of which were significantly upregulated in EVs from ALS patients. Most of them have previously been linked to ALS since they have been detected in the serum or cerebrospinal fluid of ALS patients. Among them, proteoglycan (PRG)-4, also known as lubricin, was of particular interest since it was significantly increased in ALS patients with normal cognitive and motor functions. This study highlights the significance of EVs as a promising avenue for biomarker discovery in ALS. Moreover, it sheds light on the unexpected role of PRG-4 in relation to cognitive status in ALS patients.

Chondroitin sulfate proteoglycan 4: An attractive target for antibody-based immunotherapy.

Multifunctional molecules involved in tumor progression and metastasis have been identified as valuable targets for immunotherapy. Among these, chondroitin sulfate proteoglycan 4 (CSPG4), a significant tumor cell membrane-bound proteoglycan, has emerged as a promising target, especially in light of advances in chimeric antigen receptor (CAR) T-cell therapy. The profound bioactivity of CSPG4 and its role in pivotal processes such as tumor proliferation, migration, and neoangiogenesis underline its therapeutic potential. We reviewed the molecular intricacies of CSPG4, its functional attributes within tumor cells, and the latest clinical-translational advances targeting it. Strategies such as blocking monoclonal antibodies, conjugate therapies, bispecific antibodies, small-molecule inhibitors, CAR T-cell therapies, trispecific killer engagers, and ribonucleic acid vaccines against CSPG4 were assessed. CSPG4 overexpression in diverse tumors and its correlation with adverse prognostic outcomes emphasize its significance in cancer biology. These findings suggest that targeting CSPG4 offers a promising avenue for future cancer therapy, with potential synergistic effects when combined with existing treatments.

PRG4 represses the genesis and metastasis of osteosarcoma by inhibiting PDL1 expression.

BACKGROUND: Osteosarcoma is originated from skeletal system. Recombinant human proteoglycan 4 (rhPRG4) can inhibit cell proliferation and migration in multiple cancers. This research is designed to dig out the role and mechanism of PRG4 in osteosarcoma. METHODS: Human osteosarcoma cell lines, MG63 and 143B, were transfected with programmed death 1 (PD-L1) overexpression vectors and/or treated with 20, 50, and 100 µg/mL rhPRG4, followed by the determination of cell viability, colony formation, sphere formation, invasion, migration, apoptosis, and the expressions of matrix metalloproteinases (MMPs), PD-L1 and apoptosis-related proteins. Tumor-bearing mouse models were constructed by injection of 143B cells and treatment of anti-PD-L1 antibody and/or adenovirus PRG4 (AdPRG4). Tumor volume was monitored, and immunohistochemical location of Ki67 was performed. Expressions of MMPs, transforming growth factor-ß (TGF-ß), PD-L1, and epithelial mesenchymal transition (EMT)-related proteins were measured in tumors. RESULTS: RhPRG4 (20, 50, and 100 µg/mL) inhibited the viability, colony formation, sphere formation, invasion, migration, and the expressions of MMP2, MMP9 and Bcl2 in osteosarcoma cells, while promoting cell apoptosis as well as Bax and c-caspase3 expressions, at a dose-dependent manner; by contrast, PD-L1 overexpression reversed the above effects of 100 µg/mL rhPRG4. AdPRG4 or anti-PD-L1 antibody decreased tumor volume, number of pulmonary metastasis nodule, Ki67 location, and expressions of TGF-ß, PD-L1, MMP2, MMP9, Vimentin, and Snail, but increased E-cadherin expression in tumor cells. Moreover, anti-PD-L1 antibody and AdPRG4 together functioned more effectively than them alone in reducing tumor burden. CONCLUSION: PRG4 represses the genesis and metastasis of osteosarcoma via inhibiting PD-L1 expression, and AdPRG4 enhances the effectiveness of anti-PD-L1 therapy.

Recombinant human proteoglycan 4 lowers inflammation and atherosclerosis susceptibility in female low-density lipoprotein receptor knockout mice.

Recombinant human proteoglycan 4 (rhPRG4) is a macromolecular mucin-like glycoprotein that is classically studied as a lubricant within eyes and joints. Given that endogenously produced PRG4 is present within atherosclerotic lesions and genetic PRG4 deficiency increases atherosclerosis susceptibility in mice, in the current study we investigated the anti-atherogenic potential of chronic rhPRG4 treatment. Female low-density lipoprotein receptor knockout mice were fed an atherogenic Western-type diet for 6 weeks and injected three times per week intraperitoneally with 0.5 mg rhPRG4 or PBS as control. Treatment with rhPRG4 was associated with a small decrease in plasma-free cholesterol levels, without a change in cholesteryl ester levels. A marked increase in the number of peritoneal foam cells was detected in response to the peritoneal rhPRG4 administration, which could be attributed to elevated peritoneal leukocyte MSR1 expression levels. However, rhPRG4-treated mice exhibited significantly smaller aortic root lesions of 278 ± 21 × 103 µm2 compared with 339 ± 15 × 103 µm2 in the aortic root of control mice. The overall decreased atherosclerosis susceptibility coincided with a shift in the monocyte and macrophage polarization states towards the patrolling and anti-inflammatory M2-like phenotypes, respectively. Furthermore, rhPRG4 treatment significantly reduced macrophage gene expression levels as well as plasma protein levels of the pro-inflammatory/pro-atherogenic cytokine TNF-alpha. In conclusion, we have shown that peritoneal administration and subsequent systemic exposure to rhPRG4 beneficially impacts the inflammatory state and reduces atherosclerosis susceptibility in mice. Our findings highlight that PRG4 is not only a lubricant but also acts as an anti-inflammatory agent. KEY POINTS: Endogenously produced proteoglycan 4 is found in atherosclerotic lesions and its genetic deficiency in mice is associated with enhanced atherosclerosis susceptibility. In this study we investigated the anti-atherogenic potential of chronic treatment with recombinant human PRG4 in hypercholesterolaemic female low-density lipoprotein receptor knockout mice. We show that recombinant human PRG4 stimulates macrophage foam cell formation, but also dampens the pro-inflammatory state of monocyte/macrophages, eventually leading to a significant reduction in plasma TNF-alpha levels and a lowered atherosclerosis susceptibility. Our findings highlight that peritoneal recombinant human PRG4 treatment can execute effects both locally and systemically and suggest that it will be of interest to study whether rhPRG4 treatment is also able to inhibit the progression and/or induce regression of previously established atherosclerotic lesions.

The Actin Cytoskeleton as a Regulator of Proteoglycan 4.

OBJECTIVE: The superficial zone (SZ) of articular cartilage is responsible for distributing shear forces for optimal cartilage loading and contributes to joint lubrication through the production of proteoglycan 4 (PRG4). PRG4 plays a critical role in joint homeostasis and is chondroprotective. Normal PRG4 production is affected by inflammation and irregular mechanical loading in post-traumatic osteoarthritis (PTOA). THe SZ chondrocyte (SZC) phenotype, including PRG4 expression, is regulated by the actin cytoskeleton in vitro. There remains a limited understanding of the regulation of PRG4 by the actin cytoskeleton in native articular chondrocytes. The filamentous (F)-actin cytoskeleton is a potential node in crosstalk between mechanical stimulation and cytokine activation and the regulation of PRG4 in SZCs, therefore developing insights in the regulation of PRG4 by actin may identify molecular targets for novel PTOA therapies. MATERIALS AND METHODS: A comprehensive literature search on PRG4 and the regulation of the SZC phenotype by actin organization was performed. RESULTS: PRG4 is strongly regulated by the actin cytoskeleton in isolated SZCs in vitro. Biochemical and mechanical stimuli have been characterized to regulate PRG4 and may converge upon actin cytoskeleton signaling. CONCLUSION: Actin-based regulation of PRG4 in native SZCs is not fully understood and requires further elucidation. Understanding the regulation of PRG4 by actin in SZCs requires an in vivo context to further potential of leveraging actin arrangement to arthritic therapeutics.

Downregulation of extracellular matrix protein 1 effectively ameliorates osteoarthritis progression in vivo.

Osteoarthritis (OA) is the most common joint disease whose important pathological feature is degeneration of articular cartilage. Although extracellular matrix protein 1 (ECM1) serves as a central regulator of chondrocyte proliferation and hypertrophy, its role in OA remains largely unknown. This study aims to decipher the roles of ECM1 in OA development and therapy in animal models. In the present study, ECM1 expression was examined in clinical OA samples, experimental OA mice and OA cell models. Mice subjected to destabilised medial meniscus (DMM) surgery were intra-articularly injected with adeno-associated virus (AAV) expressing ECM1 (AAV-ECM1) or AAV containing shECM1 (AAV-shECM1). Histological analysis was performed to determine cartilage damage. mRNA sequencing was performed to explore the molecular mechanism. In addition, the downstream signaling was further confirmed by using specific inhibitors. Our data showed that ECM1 was upregulated in the cartilage of patients with OA, OA mice as well as OA cell models. Moreover, ECM1 over-expressing in knee joints by AAV-ECM1 accelerated OA progression, while knockdown of ECM1 by AAV-shECM1 alleviated OA development. Mechanistically, cartilage destruction increased ECM1 expression, which consequently exacerbated OA progression partly by decreasing PRG4 expression in the TGF-ß/PKA/CREB-dependent manner. In conclusion, our study revealed the important role of ECM1 in OA progression. Targeted ECM1 inhibition is a potential strategy for OA therapy.

Astrocyte-like subpopulation of NG2 glia in the adult mouse cortex exhibits characteristics of neural progenitor cells.

Glial cells expressing neuron-glial antigen 2 (NG2), also known as oligodendrocyte progenitor cells (OPCs), play a critical role in maintaining brain health. However, their ability to differentiate after ischemic injury is poorly understood. The aim of this study was to investigate the properties and functions of NG2 glia in the ischemic brain. Using transgenic mice, we selectively labeled NG2-expressing cells and their progeny in both healthy brain and after focal cerebral ischemia (FCI). Using single-cell RNA sequencing, we classified the labeled glial cells into five distinct subpopulations based on their gene expression patterns. Additionally, we examined the membrane properties of these cells using the patch-clamp technique. Of the identified subpopulations, three were identified as OPCs, whereas the fourth subpopulation had characteristics indicative of cells likely to develop into oligodendrocytes. The fifth subpopulation of NG2 glia showed astrocytic markers and had similarities to neural progenitor cells. Interestingly, this subpopulation was present in both healthy and post-ischemic tissue; however, its gene expression profile changed after ischemia, with increased numbers of genes related to neurogenesis. Immunohistochemical analysis confirmed the temporal expression of neurogenic genes and showed an increased presence of NG2 cells positive for Purkinje cell protein-4 at the periphery of the ischemic lesion 12 days after FCI, as well as NeuN-positive NG2 cells 28 and 60 days after injury. These results suggest the potential development of neuron-like cells arising from NG2 glia in the ischemic tissue. Our study provides insights into the plasticity of NG2 glia and their capacity for neurogenesis after stroke.

Scale-Dependent Rheology of Synovial Fluid Lubricating Macromolecules.

Synovial fluid (SF) is the complex biofluid that facilitates the exceptional lubrication of articular cartilage in joints. Its primary lubricating macromolecules, the linear polysaccharide hyaluronic acid (HA) and the mucin-like glycoprotein proteoglycan 4 (PRG4 or lubricin), interact synergistically to reduce boundary friction. However, the precise manner in which these molecules influence the rheological properties of SF remains unclear. This study aimed to elucidate this by employing confocal microscopy and multiscale rheometry to examine the microstructure and rheology of solutions containing recombinant human PRG4 (rhPRG4) and HA. Contrary to previous assumptions of an extensive HA-rhPRG4 network, it is discovered that rhPRG4 primarily forms stiff, gel-like aggregates. The properties of these aggregates, including their size and stiffness, are found to be influenced by the viscoelastic characteristics of the surrounding HA matrix. Consequently, the rheology of this system is not governed by a single length scale, but instead responds as a disordered, hierarchical network with solid-like rhPRG4 aggregates distributed throughout the continuous HA phase. These findings provide new insights into the biomechanical function of PRG4 in cartilage lubrication and may have implications in the development of HA-based therapies for joint diseases like osteoarthritis.

Targeting the melanoma-associated antigen CSPG4 with HLA-C*07:01-restricted T-cell receptors.

Intorduction: Chondroitin sulfate proteoglycan 4 (CSPG4), also known as high molecular weight-melanoma associated antigen, is expressed in melanoma but also other tumor entities and constitutes an attractive target for immunotherapeutic approaches. While recent preclinical reports focused on anti-CSPG4 chimeric antigen receptors (CAR), we here explore T-cell receptor (TCR)-based approaches targeting CSPG4. Methods: The TCRs of two CSPG4-reactive T-cell clones (11C/73 and 2C/165) restricted by the highly prevalent HLA-C*07:01 allele were isolated and the respective αßTCR pairs were retrovirally expressed in CRISPR/Cas9-edited TCR-knockout T cells for functional testing. We also combined alpha and beta TCR chains derived from 11C/73 and 2C/165 in a cross-over fashion to assess for hemichain dominance. CSPG4+ melanoma, glioblastoma and lung cancer cell lines were identified and, if negative, retrovirally transduced with HLA-C*07:01. Results: Functional tests confirmed specific recognition of CSPG4+HLA-C*07:01+ target cells by the αßTCR retrieved from the parental T-cell clones and in part also by the cross-over TCR construct 2Cα-11Cß. Despite high surface expression, the 11Cα-2Cß combination, however, was not functional. Discussion: Collectively, 11C/73- and 2C/165-expressing T cells specifically and efficiently recognized CSPG4+HLA-C*07:01+ cancer cells which warrants further preclinical and clinical evaluation of these TCRs.

Plasma proteoglycan 4: a novel biomarker for acute lung injury after pediatric cardiac surgery.

Background: Identification of biological molecules related to post cardiopulmonary bypass (CPB) lung injury could help diagnose, predict and potentially impact patient's clinical course after cardiac surgery. Proteoglycan 4 (PRG4) initially identified as potential biomarker for patients with prolonged mechanical ventilation following CPB in a prior study. To further validate these findings, we sought to understand the association of lower plasma PRG4 with prolonged mechanical ventilation and worse lung compliance in a larger cohort of pediatric patients post CPB. Methods: Retrospective chart review study. Pediatric Cardiac Intensive Care Unit, Tertiary Hospital. Infants <1 year old with tetralogy of Fallot, ventricular septal defect, or atrioventricular septal defect who underwent surgical repair 2012-2020 and had stored plasma samples in our biorepository were screened for inclusion. Patients with mechanical ventilation before surgery were excluded. Patients were divided into quartiles based on postoperative duration of mechanical ventilation (control <25th percentile, study >75th percentile). Preoperative and 48-hour postoperative samples for each cohort (20 patients each) were tested for PRG4 level using enzyme-linked immunosorbent assay (ELISA) technique. Results: Study group had lower lung compliance, higher mean airway pressure and higher oxygen need postoperative when compared to control group. Plasma PRG4 levels before surgery and 48 hours postoperative were lower in study group compared to control group (P=0.0232 preoperative; P=0.0016 postoperative). Plasma PRG4 levels were compared preoperative to PRG4 levels postoperative in both group, there was no statistically significant difference (study group: P=0.0869; control group: P=0.6500). Conclusions: Lower levels of plasma PRG4 is associated with longer duration of mechanical ventilation, worse ventilator compliance and higher oxygen requirement after cardiac surgery in our patient population. Further validation of this finding in a larger and more diverse patient population is necessary prior to its application at the bedside.

A structural and functional comparison between two recombinant human lubricin proteins: Recombinant human proteoglycan-4 (rhPRG4) vs ECF843.

Proteoglycan 4 (PRG4, lubricin) is a mucin-like glycoprotein present on the ocular surface that has both boundary lubricating and anti-inflammatory properties. Full-length recombinant human PRG4 (rhPRG4) has been shown to be clinically effective in improving signs and symptoms of dry eye disease (DED). In vitro, rhPRG4 has been shown to reduce inflammation-induced cytokine production and NFκB activity in corneal epithelial cells, as well as to bind to and inhibit MMP-9 activity. A different form of recombinant human lubricin (ECF843), produced from the same cell line as rhPRG4 but manufactured using a different process, was recently assessed in a DED clinical trial. However, ECF843 did not significantly improve signs or symptoms of DED compared to vehicle. Initial published characterization of ECF843 showed it had a smaller hydrodynamic diameter and was less negatively charged than native PRG4. Further examination of the structural and functional properties of ECF843 and rhPRG4 could contribute to the understanding of what led to their disparate clinical efficacy. Therefore, the objective of this study was to characterize and compare rhPRG4 and ECF843 in vitro, both biophysically and functionally. Hydrodynamic diameter and charge were measured by dynamic light scattering (DLS) and zeta potential, respectively. Size and molecular weight was determined for individual species by size exclusion chromatography (SEC) with in-line DLS and multi-angle light scattering (MALS). Bond structure was measured by Raman spectroscopy, and sedimentation properties were measured by analytical ultracentrifugation (AUC). Functionally, MMP-9 inhibition was measured using a commercial MMP-9 activity kit, coefficient of friction was measured using an established boundary lubrication test at a latex-glass interface, and collagen 1-binding ability was measured by quart crystal microbalance with dissipation (QCMD). Additionally, the ability of rhPRG4 and ECF843 to inhibit urate acid crystal formation and cell adhesion was assessed. ECF843 had a significantly smaller hydrodynamic diameter and was less negatively charged than rhPRG4, as assessed by DLS and zeta potential. Size was further explored with SEC-DLS-MALS, which indicated that while rhPRG4 had 3 main peaks, corresponding to monomer, dimer, and multimer as expected, ECF843 had 2 peaks that were similar in size and molecular weight compared to rhPRG4's monomer peak and a third peak that was significantly smaller in both size and molar mass than the corresponding peak of rhPRG4. Raman spectroscopy demonstrated that ECF843 had significantly more disulfide bonds, which are functionally determinant structures, relative to the carbon-carbon backbone compared to rhPRG4, and AUC indicated that ECF843 was more compact than rhPRG4. Functionally, ECF843 was significantly less effective at inhibiting MMP-9 activity and functioning as a boundary lubricant compared to rhPRG4, as well as being slower to bind to collagen 1. Additionally, ECF843 was significantly less effective at inhibiting urate acid crystal formation and at preventing cell adhesion. Collectively, these data demonstrate ECF843 and rhPRG4 are significantly different in both structure and function. Given that a protein's structure sets the foundation for its interactions with other molecules and tissues in vivo, which ultimately determine its function, these differences most likely contributed to the disparate DED clinical trial results.

CSPG4 as a target for the specific killing of triple-negative breast cancer cells by a recombinant SNAP-tag-based antibody-auristatin F drug conjugate.

PURPOSE: Triple-negative breast cancer (TNBC) is phenotypic of breast tumors lacking expression of the estrogen receptor (ER), the progesterone receptor (PgR), and the human epidermal growth factor receptor 2 (HER2). The paucity of well-defined molecular targets in TNBC, coupled with the increasing burden of breast cancer-related mortality, emphasizes the need to develop targeted diagnostics and therapeutics. While antibody-drug conjugates (ADCs) have emerged as revolutionary tools in the selective delivery of drugs to malignant cells, their widespread clinical use has been hampered by traditional strategies which often give rise to heterogeneous mixtures of ADC products. METHODS: Utilizing SNAP-tag technology as a cutting-edge site-specific conjugation method, a chondroitin sulfate proteoglycan 4 (CSPG4)-targeting ADC was engineered, encompassing a single-chain antibody fragment (scFv) conjugated to auristatin F (AURIF) via a click chemistry strategy. RESULTS: After showcasing the self-labeling potential of the SNAP-tag component, surface binding and internalization of the fluorescently labeled product were demonstrated on CSPG4-positive TNBC cell lines through confocal microscopy and flow cytometry. The cell-killing ability of the novel AURIF-based recombinant ADC was illustrated by the induction of a 50% reduction in cell viability at nanomolar to micromolar concentrations on target cell lines. CONCLUSION: This research underscores the applicability of SNAP-tag in the unambiguous generation of homogeneous and pharmaceutically relevant immunoconjugates that could potentially be instrumental in the management of a daunting disease like TNBC.

Computational and experimental characterizations of the spatiotemporal activity and functional role of TGF-ß in the synovial joint.

TGF-ß is a prominent anabolic signaling molecule associated with synovial joint health. Recent work has uncovered mechanochemical mechanisms that activate the latent form of TGF-ß (LTGF-ß) in the synovial joint-synovial fluid (SF) shearing or cartilage compression-pointing to mechanobiological phenomena, whereby enhanced TGF-ß activity occurs during joint stimulation. Here, we implement computational and experimental models to better understand the role of mechanochemical-activated TGF-ß (aTGF-ß) in regulating the functional biosynthetic activities of synovial joint tissues. Reaction-diffusion models describe the pronounced role of extracellular chemical reactions-load-induced activation, reversible ECM-binding, and cell-mediated internalization-in modulating the spatiotemporal distribution of aTGF-ß in joint tissues. Of note, aTGF-ß from SF shearing predominantly acts on cells in peripheral tissue regions (superficial zone [SZ] chondrocytes and synoviocytes) and aTGF-ß from cartilage compression acts on chondrocytes through all cartilage layers. Further, ECM reversible binding sites in cartilage act to modulate the temporal delivery of aTGF-ß to cells, creating a dynamic where short durations of joint activity give rise to extended periods of aTGF-ß exposure at moderated doses. Ex vivo tissue models were subsequently utilized to characterize the influence of physiologic aTGF-ß activity regimens in regulating functional biosynthetic activities. Physiologic exposure regimens of aTGF-ß in SF induce strong 4-fold to 9-fold enhancements in the secretion rate of the synovial biolubricant, PRG4, from SZ cartilage and synovium explants. Further, aTGF-ß inhibition in cartilage over 1-month culture leads to a pronounced loss of GAG content (30-35% decrease) and tissue softening (60-65% EY reduction). Overall, this work advances a novel perspective on the regulation of TGF-ß in the synovial joint and its role in maintaining synovial joint health.

Pseudogene CSPG4P12 affects the biological behavior of non­small cell lung cancer by Bcl­2/Bax mitochondrial apoptosis pathway.

Increasing evidence has shown that chondroitin sulfate proteoglycan 4 (CSPG4) serve a critical role in tumor progression. However, the roles of chondroitin sulfate proteoglycan 4 pseudogene 12 (CSPG4P12) remain to be elucidated. The present study aimed to investigate the potential effects of CSPG4P12 on the physiological behaviors of non-small cell lung cancer (NSCLC) and its underlying biological mechanism. The expression levels of CSPG4P12 in NSCLC tissues and adjacent normal tissues were analyzed using the gene expression profiling interactive analysis 2 database and reverse transcription-quantitative PCR. Cell Counting Kit-8 and colony formation assays were performed to measure cell proliferation. In addition, Transwell and wound healing assays were performed to assess cell invasion and migration. Cell adhesion was measured by cell-extracellular matrix adhesion assay. Hoechst 33342 staining assay was performed to detect nucleoli of apoptotic cells, and transmission electron microscopy (TEM) was utilized for apoptosis detection. Immunofluorescence and western blot assays were performed to measure the expression levels of apoptosis-related proteins. The present results revealed that the expression levels of CSPG4P12 in NSCLC tissues were significantly lower compared with those in adjacent normal tissues. Overexpression of CSPG4P12 inhibited cell proliferation, invasion, migration and adhesion whilst promoting apoptosis. There were missing mitochondrial cristae and mitochondrial vacuoles in the CSPG4P12-overexpressed cells when observed under TEM. Overexpression of CSPG4P12 also increased the expression of Bax and p53, whereas it inhibited the expression of Bcl2. In conclusion, CSPG4P12 could inhibit NSCLC development and tumorigenesis by activating the p53/Bcl2/Bax mitochondrial apoptotic pathway.

The role of pericytes on the efficacy of bevacizumab in colorectal cancer.

BACKGROUND: Pericytes are mesenchymal cells surrounding capillary vessels and are known to play an essential role in tumor angiogenesis. Chondroitin sulfate proteoglycan 4 (CSPG4) is a cell surface proteoglycan and its release from pericytes and vascular smooth muscle cells is very important in tumor angiogenesis. Bevacizumab, which is a monoclonal antibody frequently used in the treatment of metastatic colorectal cancer, binds to the ligand of vascular endothelial growth factor A (VEGFA) and inhibits tumor angiogenesis. However, no reliable biomarker for predicting patients that will show a good response to this therapy has been established yet. In this study, we aimed to identify the significance of the presence of pericyte and VEGFA and CSPG4 expressions on the efficacy of Bevacizumab. METHODS: Fifty patients with metastatic or recurrent colorectal cancer who had been treated with Bevacizumab combined chemotherapy treatment were included in the study. The expressions of VEGFA and CSPG4 genes and also human ß-actin as the reference gene were examined using the quantitative real-time polymerase chain reaction method in the formalin-fixed paraffinembedded tumor tissues. For determining vascular and pericyte density in tumor tissue, immunohistochemical analysis was performed with CD31, alpha-smooth muscle actin, and CD34 antibodies. RESULTS: CSPG4 positive group had better objective response rate, as well as longer progression-free and overall survival than CSPG4 negative ones. Progression-free survival was significantly longer in VEGFA low group and CD31 low group. No significant correlation was found between CD34 positivity, SMA positivity, and progression-free and overall survival. DISCUSSION: Our results suggested that bevacizumab may be more effective in patients having less vascular density in the tumor tissue. But further studies are needed to support this finding.

Proteoglycan-4 predicts good prognosis in patients with hepatocellular carcinoma receiving transcatheter arterial chemoembolization and inhibits cancer cell migration in vitro.

Purpose: To search for adaptive response molecules that affect the efficacy of transcatheter arterial chemoembolization (TACE), analyze their clinical correlation with and prognostic value for hepatocellular carcinoma (HCC), and explore their impact on cell biological behavior and their mechanisms of action. Methods: HCC tissue gene sequencing was used to identify differentially expressed genes. The expression of proteoglycan 4 (PRG4) in the serum of 117 patients with HCC who received TACE was detected by enzyme-linked immunosorbent assay. Serum-free medium mimicked TACE-induced nutrient deprivation. Cells with stable knockdown of PRG4 (shPRG4) were constructed to verify the effect and mechanism of PRG4 on the biological behavior of HCC cells in vitro. Results: The expression of PRG4 was significantly elevated under TACE-induced starvation conditions. Low PRG4 expression was associated with worse response to TACE treatment, shorter survival time, and stronger HCC migration ability. Furthermore, in vitro experiments showed that knockdown of PRG4 promoted HCC cell migration by enhancing epithelial-mesenchymal transition (EMT) while did not affect proliferation. When PRG4 expression was low, starvation treatment impaired the migratory ability of HCC cells and reduced the chemosensitivity of HCC cells to epirubicin. Conclusions: PRG4 expression predicts survival and TACE treatment response in patients with HCC. Furthermore, knockdown of PRG4 enhanced EMT, leading to HCC cell migration. PRG4 may serve as a biomarker for HCC patients receiving TACE.

Recombinant Human Proteoglycan 4 (rhPRG4) Downregulates TNFα-Stimulated NFκB Activity and FAT10 Expression in Human Corneal Epithelial Cells.

Dry Eye Disease (DED) is a complex pathology affecting millions of people with significant impact on quality of life. Corneal inflammation, including via the nuclear factor kappa B (NFκB) pathway, plays a key etiological role in DED. Recombinant human proteoglycan 4 (rhPRG4) has been shown to be a clinically effective treatment for DED that has anti-inflammatory effects in corneal epithelial cells, but the underlying mechanism is still not understood. Our goal was to understand if rhPRG4 affects tumor necrosis factor α (TNFα)-stimulated inflammatory activity in corneal epithelial cells. We treated hTERT-immortalized corneal epithelial (hTCEpi) cells ± TNFα ± rhPRG4 and performed Western blotting on cell lysate and RNA sequencing. Bioinformatics analysis revealed that rhPRG4 had a significant effect on TNFα-mediated inflammation with potential effects on matricellular homeostasis. rhPRG4 reduced activation of key inflammatory pathways and decreased expression of transcripts for key inflammatory cytokines, interferons, interleukins, and transcription factors. TNFα treatment significantly increased phosphorylation and nuclear translocation of p65, and rhPRG4 significantly reduced both these effects. RNA sequencing identified human leukocyte antigen (HLA)-F adjacent transcript 10 (FAT10), a ubiquitin-like modifier protein which has not been studied in the context of DED, as a key pro-inflammatory transcript increased by TNFα and decreased by rhPRG4. These results were confirmed at the protein level. In summary, rhPRG4 is able to downregulate NFκB activity in hTCEpi cells, suggesting a potential biological mechanism by which it may act as a therapeutic for DED.

Truncated lubricin glycans in osteoarthritis stimulate the synoviocyte secretion of VEGFA, IL-8, and MIP-1α: Interplay between O-linked glycosylation and inflammatory cytokines.

The primary aim of the study was to identify inflammatory markers relevant for osteoarthritis (OA)-related systemic (plasma) and local (synovial fluid, SF) inflammation. From this, we looked for inflammatory markers that coincided with the increased amount of O-linked Tn antigen (GalNAcα1-Ser/Thr) glycan on SF lubricin. Inflammatory markers in plasma and SF in OA patients and controls were measured using a 44-multiplex immunoassay. We found consistently 29 markers detected in both plasma and SF. The difference in their concentration and the low correlation when comparing SF and plasma suggests an independent inflammatory environment in the two biofluids. Only plasma MCP-4 and TARC increased in our patient cohort compared to control plasma. To address the second task, we concluded that plasma markers were irrelevant for a direct connection with SF glycosylation. Hence, we correlated the SF-inflammatory marker concentrations with the level of altered glycosylation of SF-lubricin. We found that the level of SF-IL-8 and SF-MIP-1α and SF-VEGFA in OA patients displayed a positive correlation with the altered lubricin glycosylation. Furthermore, when exposing fibroblast-like synoviocytes from both controls and OA patients to glycovariants of recombinant lubricin, the secretion of IL-8 and MIP-1α and VEGFA were elevated using lubricin with Tn antigens, while lubricin with sialylated and nonsialylated T antigens had less or no measurable effect. These data suggest that truncated glycans of lubricin, as found in OA, promote synovial proinflammatory cytokine production and exacerbate local synovial inflammation.

Roles of Cartilage-Resident Stem/Progenitor Cells in Cartilage Physiology, Development, Repair and Osteoarthritis.

Osteoarthritis (OA) is a degenerative disease that causes irreversible destruction of articular cartilage for which there is no effective treatment at present. Although articular cartilage lacks intrinsic reparative capacity, numerous studies have confirmed the existence of cartilage-resident stem/progenitor cells (CSPCs) in the superficial zone (SFZ) of articular cartilage. CSPCs are characterized by the expression of mesenchymal stromal cell (MSC)-related surface markers, multilineage differentiation ability, colony formation ability, and migration ability in response to injury. In contrast to MSCs and chondrocytes, CSPCs exhibit extensive proliferative and chondrogenic potential with no signs of hypertrophic differentiation, highlighting them as suitable cell sources for cartilage repair. In this review, we focus on the organizational distribution, markers, cytological features and roles of CSPCs in cartilage development, homeostasis and repair, and the application potential of CSPCs in cartilage repair and OA therapies.