Photobiomodulation inhibits the expression of chondroitin sulfate proteoglycans after spinal cord injury via the Sox9 pathway

Both glial cells and glia scar greatly affect the development of spinal cord injury and have become hot spots in research on spinal cord injury treatment.The cellular deposition of dense extracellular matrix proteins such as chondroitin sulfate proteoglycans inside and around the glial scar is known to affect axonal growth and be a major obstacle to autogenous repair.These proteins are thus candidate targets for spinal cord injury therapy.Our previous studies demonstrated that 810 nm photo biomodulation inhibited the formation of chondroitin sulfate proteoglycans after spinal cord injury and greatly improved motor function in model animals.However,the specific mechanism and potential targets involved remain to be clarified.In this study,to investigate the therapeutic effect of photo biomodulation,we established a mouse model of spinal cord injury by T9 clamping and irradiated the injury site at a power density of 50 mW/cm~2 for 50 minutes once a day for 7 consecutive days.We found that photobiomodulation greatly restored motor function in mice and down regulated chondroitin sulfate proteoglycan expression in the injured spinal cord.Bioinformatics analysis revealed that photobiomodulation inhibited the expression of proteoglycan-related genes induced by spinal cord injury,and versican,a type of proteoglycan,was one of the most markedly changed molecules.Immunofluorescence staining showed that after spinal cord injury,versican was present in astrocytes in spinal cord tissue.The expression of versican in primary astrocytes cultured in vitro increased after inflammation induction,whereas photobiomodulation inhibited the expression of ve rsican.Furthermore,we found that the increased levels of p-Smad3,p-P38 and p-Erk in inflammatory astrocytes were reduced after photobiomodulation treatment and after delivery of inhibitors including FR 180204,(E)-SIS3,and SB 202190.This suggests that Sma d 3/Sox9 and MAP K/Sox9 pathways may be involved in the effects of photobiomodulation.In summary,our findings show that photobiomodulation modulates the expression of chondroitin sulfate proteoglycans,and versican is one of the key target molecules of photo biomodulation.MAPK/Sox9 and Smad3/Sox9 pathways may play a role in the effects of photo biomodulation on chondroitin sulfate proteoglycan accumulation after spinal cord injury.

Proteoglycans: Road Signs for Neurite Outgrowth

Proteoglycans in the central nervous system play integral roles as ＂traffic signals＂ for the direction of neurite outgrowth. This attribute of proteoglycans is a major factor in regeneration of the injured central nervous system. In this review, the structures of proteoglycans and the evidence suggesting their involvement in the response following spinal cord injury are presented. The review further describes the methods routinely used to determine the effect proteoglycans have on neurite outgrowth. The effects of proteoglycans on neurite outgrowth are not completely understood as there is disagreement on what component of the molecule is interacting with growing neurites and this ambiguity is chronicled in an historical context. Finally, the most recent findings suggesting possible receptors, interactions, and sulfation patterns that may be important in eliciting the effect of proteoglycans on neurite outgrowth are discussed. A greater understanding of the proteoglycan-neurite interaction is necessary for successfully promoting regeneration in the iniured central nervous system.

Proteoglycans in liver cancer

Proteoglycans are a group of molecules that contain at least one glycosaminoglycan chain,such as a heparan,dermatan,chondroitin,or keratan sulfate,covalently attached to the protein core.These molecules arecategorized based on their structure,localization,and function,and can be found in the extracellular matrix,on the cell surface,and in the cytoplasm.Cell-surface heparan sulfate proteoglycans,such as syndecans,are the primary type present in healthy liver tissue.However,deterioration of the liver results in overproduction of other proteoglycan types.The purpose of this article is to provide a current summary of the most relevant data implicating proteoglycans in the development and progression of human and experimental liver cancer.A review of our work and other studies in the literature indicate that deterioration of liver function is accompanied by an increase in the amount of chondroitin sulfate proteoglycans.The alteration of proteoglycan composition interferes with the physiologic function of the liver on several levels.This article details and discusses the roles of syndecan-1,glypicans,agrin,perlecan,collagen XVIII/endostatin,endocan,serglycin,decorin,biglycan,asporin,fibromodulin,lumican,and versican in liver function.Specifically,glypicans,agrin,and versican play significant roles in the development of liver cancer.Conversely,the presence of decorin could potentially provide protective effects.

Inhibition and enhancement of neural regeneration by chondroitin sulfate proteoglycans

The current dogma in neural regeneration research implies that chondroitin sulfate proteoglycans（CSPGs） inhibit plasticity and regeneration in the adult central nervous system（CNS）. We argue that the role of the CSPGs can be reversed from inhibition to activation by developmentally expressed CSPG-binding factors. Heparin-binding growth-associated molecule（HB-GAM; also designated as pleiotrophin） has been studied as a candidate molecule that might modulate the role of CSPG matrices in plasticity and regeneration. Studies in vitro show that in the presence of soluble HB-GAM chondroitin sulfate（CS） chains of CSPGs display an enhancing effect on neurite outgrowth. Based on the in vitro studies, we suggest a model according to which the HB-GAM/CS complex binds to the neuron surface receptor glypican-2, which induces neurite growth. Furthermore, HB-GAM masks the CS binding sites of the neurite outgrowth inhibiting receptor protein tyrosine phosphatase sigma（PTPσ）, which may contribute to the HB-GAM-induced regenerative effect. In vivo studies using two-photon imaging after local HB-GAM injection into prick-injury of the cerebral cortex reveal regeneration of dendrites that has not been previously demonstrated after injuries of the mammalian nervous system. In the spinal cord, two-photon imaging displays HB-GAM-induced axonal regeneration. Studies on the HB-GAM/CS mechanism in vitro and in vivo are expected to pave the way for drug development for injuries of brain and spinal cord.

Effect of chondroitin sulfate proteoglycans on neuronal cell adhesion, spreading and neurite growth in culture

As one major component of extracellular matrix （ECM） in the central nervous system, chondroitin sul- fate proteoglycans （CSPGs） have long been known as inhibitors enriched in the glial scar that prevent axon regeneration after injury. Although many studies have shown that CSPGs inhibited neurite out- growth in vitro using different types of neurons, the mechanism by which CSPGs inhibit axonal growth remains poorly understood. Using cerebellar granule neuron （CGN） culture, in this study, we evaluated the effects of different concentrations of both immobilized and soluble CSPGs on neuronal growth, in- cluding cell adhesion, spreading and neurite growth. Neurite length decreased while CSPGs concentration arised, meanwhile, a decrease in cell density accompanied by an increase in cell aggregates formation was observed. Soluble CSPGs also showed an inhibition on neurite outgrowth, but it required a higher concen- tration to induce cell aggregates formation than coated CSPGs. We also found that growth cone size was significantly reduced on CSPGs and neuronal cell spreading was restrained by CSPGs, attributing to an inhibition on lamellipodial extension. The effect of CSPGs on neuron adhesion was further evidenced by interference reflection microscopy （IRM） which directly demonstrated that both CGNs and cerebral cortical neurons were more loosely adherent to a CSPG substrate. These data demonstrate that CSPGs have an effect on cell adhesion and spreading in addition to neurite outgrowth.

Traffic lights for axon growth: proteoglycans and their neuronal receptors

Axon growth is a central event in the development and post-injury plasticity of the nervous system. Growing axons encounter a wide variety of environmental instructions. Much like traffic lights in controlling the migrating axons, chondroitin sulfate proteoglycans （CSPGs） and heparan sulfate proteoglycans （HSPGs） often lead to ＂stop＂ and ＂go＂ growth responses in the axons, respectively. Recently, the LAR family and NgR family molecules were identified as neuronal receptors for CSPGs and HSPGs. These discoveries provided molecular tools for further study of mechanisms underlying axon growth regulation. More importantly, the identification of these proteoglycan receptors offered potential therapeutic targets for promoting post-injury axon regeneration.

In Silico Study on Sulfated and Non-Sulfated Carbohydrate Chains from Proteoglycans in Cnidaria and Their Interaction with Collagen

Proteoglycans and collagen molecules are interacting with each other thereby forming various connective tissues. The sulfation pattern of proteoglycans differs depending on the kind of tissue and/or the degree of maturation. Tissues from Cnidaria are suitable examples for exploration of the effects in relation to the presence and the absence of sulfate groups, when studying characteristic fragments of the long proteoglycan carbohydrate chains in silico. It has been described that a non-sulfated chondroitin appears as a scaffold in early morphogenesis of all nematocyst types in Hydra. On the other hand, sulfated glucosaminoglycans play an important role in various developmental processes of Cnidaria. In order to understand this biological phenomenon on a sub-molecular level we have analysed the structures of sulfated and non-sulfated proteoglycan carbohydrate chains as well as the structure of diverse collagen molecules with computational methods including quantum chemical calculations. The strong interactions between the sulfate groups of the carbohydrates moieties in proteoglycans and positively charged regions of collagen are essential in stabilizing various Cnidaria tissues but could hinder the nematocyst formation and its proper function. The results of our quantum chemical calculations show that the sulfation pattern has a significant effect on the conformation of chondroitin structures under study.

Proteoglycans and their functions in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma(ESCC)is a highly malignant disease that has a poor prognosis.Its high lethality is mainly due to the lack of symptoms at early stages,which culminates in diagnosis at a late stage when the tumor has already metastasized.Unfortunately,the common cancer biomarkers have low sensitivity and specificity in esophageal cancer.Therefore,a better understanding of the molecular mechanisms underlying ESCC progression is needed to identify novel diagnostic markers and therapeutic targets for intervention.The invasion of cancer cells into the surrounding tissue is a crucial step for metastasis.During metastasis,tumor cells can interact with extracellular components and secrete proteolytic enzymes to remodel the surrounding tumor microenvironment.Proteoglycans are one of the major components of extracellular matrix.They are involved in multiple processes of cancer cell invasion and metastasis by interacting with soluble bioactive molecules,surrounding matrix,cell surface receptors,and enzymes.Apart from having diverse functions in tumor cells and their surrounding microenvironment,proteoglycans also have diagnostic and prognostic significance in cancer patients.However,the functional significance and underlying mechanisms of proteoglycans in ESCC are not well understood.This review summarizes the proteoglycans that have been studied in ESCC in order to provide a comprehensive view of the role of proteoglycans in the progression of this cancer type.A long term goal would be to exploit these molecules to provide new strategies for therapeutic intervention.

Increased expression of chondroitin sulphate proteoglycans in rat hepatocellular carcinoma tissues

AIM:To investigate the expression of chondroitin sulphate proteoglycans(CSPGs)in rat liver tissues of hepatocellular carcinoma(HCC).METHODS:Thirty male Sprague Dawley rats were randomly divided into two groups:control group(n=10) and HCC model group(n=20).Rats in the HCC model groups were intragastrically administrated with 0.2%(w/v)N-diethylnitrosamine(DEN)every 5 d for 16 wk,whereas 0.9%(w/v)normal saline was administered to rats in the control group.After 16 wk from the initiation of experiment,all rats were killed and livers were collected and fixed in 4%(w/v)paraformaldehyde.All tissues were embedded in paraffin and sectioned.Histological staining(hematoxylin and eosin and Toluidine blue)was performed to demonstrate the onset of HCC and the content of sulphated glycosaminoglycan(sGAG).Immunohistochemical staining was performed to investigate the expression of chondroitin sulphate(CS)/dermatan sulphate(DS)-GAG,heparan sulphate(HS)-GAG,keratan sulphate(KS)-GAG in liver tissues.Furthermore,expression and distribution of CSPG family members,including aggrecan,versican,biglycan and decorin in liver tissues,were also immunohistochemically determined.RESULTS:After 16 wk administration of DEN,malignant nodules were observed on the surface of livers from the HCC model group,and their hepatic lobule structures appeared largely disrupted under microscope.Toluidine blue staining demonstrated that there was an significant increase in sGAG content in HCC tissues when compared with that in the normal liver tissues from the control group[0.37±0.05 integrated optical density per stained area(IOD/area)and 0.21± 0.01 IOD/area,P<0.05].Immunohistochemical studies demonstrated that this increased sGAG in HCC tissues was induced by an elevated expression of CS/DS(0.28±0.02 IOD/area and 0.18±0.02 IOD/area,P< 0.05)and HS(0.30±0.03 IOD/area and 0.17±0.02 IOD/area,P<0.01)but not KS GAGs in HCC tissues.Further studies thereby were performed to investigate the expression and distribution of several CSPG components in HCC tissues,including aggrecan,versican,biglycan and decorin.Interestingly,there was a distinct distribution pattern for these CSPG components between HCC tissues and the normal tissues.Positive staining of aggrecan,biglycan and decorin was localized in hepatic membrane and/or pericellular matrix in normal liver tissues;however,their expression was mainly observed in the cytoplasm,cell membranes in hepatoma cells and/or pericellular matrix within HCC tissues.Semi-quantitative analysis indicated that there was a higher level of expression of aggrecan(0.43± 0.01 and 0.35±0.03,P<0.05),biglycan(0.32±0.01 and 0.25±0.01,P<0.001)and decorin(0.29±0.01 and 0.26±0.01,P<0.05)in HCC tissues compared with that in the normal liver tissues.Very weak versican positive staining was observed in hepatocytes near central vein in normal liver tissues;however there was an intensive versican distribution in fibrosis septa between the hepatoma nodules.Semi-quantitative analysis indicated that the positive rate of versican in hepatoma tissues from the HCC model group was much higher than that in the control group(33.61%and 21.28%,P <0.05).There was no positive staining in lumican and keratocan,two major KSPGs,in either normal or HCC liver tissues.CONCLUSION:CSPGs play important roles in the onset and progression of HCC,and may provide potential therapeutic targets and clinical biomarkers for this prevalent tumor in humans.

EXTRACTION AND ISOLATION OF PROTEOGLYCANS FROM RAT BRAIN

This paper reports a comparative study of the extraction rate of rat brain proteoglycans (PGs) by three different methods, with chromatography, papain digestion and electrophoretic technique. The results showed: ① The extraction rate of brain PGs by 4mol/L guanidine HCl (GuHCl)was higher than that by phosphate-buffered saline (PBS) In any method, however the protein/PGs ratio in the GuHCl-extract was lower than that in the PBS-extract. ② PBS mainly extracted the soluble chondroitin sulfate proteoglycan (CSPG), whereas the 4mol/L GuHCl could extracted both soluble CSPG and insoluble heparan sulfate proteoglycan (HSPG). ③ After delipidation of brain by organic reagents, the extraction rate of delipidized brain PGs either by the PBS or by the 4mol/L GuHCl decreased obviously. ④ By direct extraction with PBS, GuHCl seguentially, few amount of PGs in the residue from brain was found.

Interaction of arterial proteoglycans with low density lipoproteins(LDLs):From theory to promising therapeutic approaches

Although atherosclerosis is a multifactorial process,proteoglycans mediated lipoprotein(LDL)retention at the subendothelial space is a necessary and sufficient event in provoking lesion initiation.Proteoglycans(PGs)are usually composed of one core protein backbone with one or more glycosaminoglycan chains(GAGs)covalently linked,mainly include perlecan,biglycan,versican,and decorin.The interaction between LDL and proteoglycans is apparently mediated by the basic amino acids in apoB-100,the moiety of LDL,electrostatic interacting with the negatively charged GAGs(sulfate or carbohydrate groups)of proteoglycans or though some bridge molecules like sphingomyelinase(SMase)or lipoprotein lipase(LpL).In the later section,we collate the promising therapeutic approaches that have been proposed up to now,targeting LDL-PGs interaction.It should be concluded that previous studies on interaction between LDL and PGs mainly focused on perlecan,biglycan,decorin,and versican that all located in the extracellular matrix(ECM),future studies should pay more attention to the endothelial surface glycocalyx and its interaction with LDLs,seeking promising therapeutic targets more specifically.

Abnormal Proteoglycans Secreted by Chondrocytes in Actions of Fulvic Acid and Reactive Oxygen Species

Articular cartilage is an avascular and non-nervous tissue. The transport of metabolites to and from the chondrocytes has to take place through the matrix and hence depends on its composition and structure. A major parameter controlling the properties of cartilage is the proteoglycan (PG) content of the matrix, whose small

Axonal growth inhibitors and their receptors in spinal cord injury:from biology to clinical translation

Axonal growth inhibitors are released during traumatic injuries to the adult mammalian central nervous system, including after spinal cord injury. These molecules accumulate at the injury site and form a highly inhibitory environment for axonal regeneration. Among these inhibitory molecules, myelinassociated inhibitors, including neurite outgrowth inhibitor A, oligodendrocyte myelin glycoprotein, myelin-associated glycoprotein, chondroitin sulfate proteoglycans and repulsive guidance molecule A are of particular importance. Due to their inhibitory nature, they represent exciting molecular targets to study axonal inhibition and regeneration after central injuries. These molecules are mainly produced by neurons, oligodendrocytes, and astrocytes within the scar and in its immediate vicinity. They exert their effects by binding to specific receptors, localized in the membranes of neurons. Receptors for these inhibitory cues include Nogo receptor 1, leucine-rich repeat, and Ig domain containing 1 and p75 neurotrophin receptor/tumor necrosis factor receptor superfamily member 19(that form a receptor complex that binds all myelin-associated inhibitors), and also paired immunoglobulin-like receptor B. Chondroitin sulfate proteoglycans and repulsive guidance molecule A bind to Nogo receptor 1, Nogo receptor 3, receptor protein tyrosine phosphatase σ and leucocyte common antigen related phosphatase, and neogenin, respectively. Once activated, these receptors initiate downstream signaling pathways, the most common amongst them being the Rho A/ROCK signaling pathway. These signaling cascades result in actin depolymerization, neurite outgrowth inhibition, and failure to regenerate after spinal cord injury. Currently, there are no approved pharmacological treatments to overcome spinal cord injuries other than physical rehabilitation and management of the array of symptoms brought on by spinal cord injuries. However, several novel therapies aiming to modulate these inhibitory proteins and/or their receptors are under investigation in ongoing clinical trials. Investigation has also been demonstrating that combinatorial therapies of growth inhibitors with other therapies, such as growth factors or stem-cell therapies, produce stronger results and their potential application in the clinics opens new venues in spinal cord injury treatment.

Galectin-14 promotes hepatocellular carcinoma tumor growth via enhancing heparan sulfate proteoglycan modification

Hepatocellular carcinoma(HCC)is a highly heterogeneous malignancy and lacks effective treatment.Bulk-sequencing of different gene transcripts by comparing HCC tissues and adjacent normal tissues provides some clues for investigating the mechanisms or identifying potential targets for tumor progression.However,genes that are exclusively expressed in a subpopulation of HCC may not be enriched or detected through such a screening.In the current study,we performed a single cell-clone-based screening and identified galectin-14 as an essential molecule in the regulation of tumor growth.The aberrant expression of galectin-14 was significantly associated with a poor overall survival of liver cancer patients with database analysis.Knocking down galectin-14 inhibited the proliferation of tumor growth,whereas overexpressing galectin-14 promoted tumor growth in vivo.Non-targeted metabolomics analysis indicated that knocking down galectin-14 decreased glycometabolism;specifically that glycoside synthesis was significantly changed.Further study found that galectin-14 promoted the expression of cell surface heparan sulfate proteoglycans(HSPGs)that functioned as co-receptors,thereby increasing the responsiveness of HCC cells to growth factors,such as epidermal growth factor and transforming growth factor-alpha.In conclusion,the current study identifies a novel HCC-specific molecule galectin-14,which increases the expression of cell surface HSPGs and the uptake of growth factors to promote HCC cell proliferation.

Chondroitinase ABC plus bone marrow mesenchymal stem cells for repair of spinal cord injury

As chondroitinase ABC can improve the hostile microenvironment and cell transplantation is proven to be effective after spinal cord injury, we hypothesized that their combination would be a more effective treatment option. At 5 days after T8 spinal cord crush injury, rats were injected with bone marrow mesenchymal stem cell suspension or chondroitinase ABC 1 mm from the edge of spinal cord damage zone. Chondroitinase ABC was first injected, and bone marrow mesenchymal stem cell suspension was injected on the next day in the combination group. At 14 days, the mean Basso, Beattie and Bresnahan score of the rats in the combination group was higher than other groups. Hematoxylin-eosin staining showed that the necrotic area was significantly reduced in the combination group compared with other groups. Glial fibrillary acidic protein-chondroitin sulfate proteoglycan double staining showed that the damage zone of astrocytic scars was significantly reduced without the cavity in the combination group. Glial fibrillary acidic protein/growth associated protein-43 double immunostaining revealed that positive fibers traversed the damage zone in the combination group. These results suggest that the combination of chondroitinase ABC and bone marrow mesenchymal stem cell transplantation contributes to the repair of spinal cord injury.

Epidural electrical stimulation for spinal cord injury

A long-standing goal of spinal cord injury research is to develop effective repair strategies,which can restore motor and sensory functions to near-normal levels.Recent advances in clinical management of spinal cord injury have significantly improved the prognosis,survival rate and quality of life in patients with spinal cord injury.In addition,a significant progress in basic science research has unraveled the underlying cellular and molecular events of spinal cord injury.Such efforts enabled the development of pharmacologic agents,biomaterials and stem-cell based therapy.Despite these efforts,there is still no standard care to regenerate axons or restore function of silent axons in the injured spinal cord.These challenges led to an increased focus on another therapeutic approach,namely neuromodulation.In multiple animal models of spinal cord injury,epidural electrical stimulation of the spinal cord has demonstrated a recovery of motor function.Emerging evidence regarding the efficacy of epidural electrical stimulation has further expanded the potential of epidural electrical stimulation for treating patients with spinal cord injury.However,most clinical studies were conducted on a very small number of patients with a wide range of spinal cord injury.Thus,subsequent studies are essential to evaluate the therapeutic potential of epidural electrical stimulation for spinal cord injury and to optimize stimulation parameters.Here,we discuss cellular and molecular events that continue to damage the injured spinal cord and impede neurological recovery following spinal cord injury.We also discuss and summarize the animal and human studies that evaluated epidural electrical stimulation in spinal cord injury.

Effects of Taxotere on invasive potential and multidrug resistance phenotype in pancreatic carcinoma cell line SUIT-2

INTRODUCTIONDevelopment of drug-resistance to chemotherapyand subsequent metastasis of tumor are primarilyresponsible for treatment failure and the death fromcancer. There have been many previous studies onthe relationship between expression of multidrugresistance (MDR) phenotype P-glycoprotein (P-gp)and the malignant properties of tumors, but theresults are often conflicting[1-8]. The difference intumor types or MDR phenotype induced by specificagents might account for this discrepancy. Taxotere(TXT), a member of the family of taxanes, hasantitumor activity through its effect of promotingthe polymerization of tubulin[9,10].

Arylsulfatase,β-galactosidase and lysozyme in gastric cancer cells and its relationship to invasion

IM To study the distribution of arylsulfatase, βgalactosidase and lysozyme in gastric cancer cells, and its relationship to differentiation and invasion of gastric cancer cells.METHODS Histochemical, immunohistochemical and ruthenium red (RR) electrocytochemical technique for three types of hydrolases and proteoglycans in pericancerous matrix in 33 cases of gastric cancer were observed under light and electron microscopy.RESULTS The expression intensities of arylsulfatase, βglactosidase and lysozyme in mucinous cell carcinomas were more intensive than those in welldifferentiated and poorlydifferentiated adenocarcinomas (P<005-001). The fibrous tissues smooth muscle and proteoglycans close to the cancer cells were degraded. They were found in the region far from the cancer cells. Expression of three enzymes mentioned above was low in adenocarcinoma cells, and fibrous tissues and RR granules were present and intact near the welldifferentiated and poorly differentiated adenocarcinoma cells.CONCLUSION Mucinous cell carcinoma may release various hydrolases into extracellular matrix, inducing degradation of pericancerous matrix and facilitating cancer cell invasion and metastasis..

Glycosaminoglycan remodeling during diabetes and the role of dietary factors in their modulation

Glycosaminoglycans(GAGs) play a significant role in various aspects of cell physiology.These are complex polymeric molecules characterized by disaccharides comprising of uronic acid and amino sugar.Compounded to the heterogeneity,these are variously sulfated and epimerized depending on the class of GAG.Among the various classes of GAG,namely,chondroitin/dermatan sulfate,heparin/heparan sulfate,keratan sulfate and hyaluronic acid(HA),only HA is non-sulfated.GAGs are known to undergo remodeling in various tissues during various pathophysiological conditions,diabetes mellitus being one among them.These changes will likely affect their structure thereby impinging on their functionality.Till date,diabetes has been shown to affect GAGs in organs such as kidney,liver,aorta,skin,erythrocytes,etc.to name a few,with deleterious consequences.One of the mainstays in the treatment of diabetes is though dietary means.Various dietary factors are known to play a significant role in regulating glucose homeostasis.Furthermore,in recent years,there has been a keen interest to decipher the role of dietary factors on GAG metabolism.This review focuses on the remodeling of GAGs in various organs during diabetes and their modulation by dietary factors.While effect of diabetes on GAG metabolism has been worked out quite a bit,studies on the role of dietary factors in their modulation has been few and far between.We have tried our best to give the latest reports available on this subject.

The contribution of proteoglycans to heterogeneity and temozolomide resistance of glioblastoma cells

Aim:Heterogeneity of glioblastoma(GB)cells significantly contributes to tumor resistance against temozolomide(TMZ)and the development of disease relapse.Multiple molecular mechanisms are involved in this process,yet the contribution of proteoglycans(PGs)remains unknown.This study aimed to investigate the potential involvement of PGs(both at core proteins and polysaccharide chains)in the heterogeneity and TMZ resistance of GB cells.Methods:Seven human GB cell lines were characterized for TMZ sensitivity,cell phenotypic traits,gene expression for glucocorticoid receptor(GR,NR3C1),PG core proteins-and heparan sulfate(HS)biosynthesis-related genes and content of their chondroitin sulfate(CS)and HS chains.Results:Although the studied cell lines have similar proliferation rates,they significantly differ in their migration activity,clonogenicity,and TMZ resistance(IC508.51-369.59µM in the line of U343,LN215,HS683,U87,LN71,LN405,LN18),creating a specific phenotype for each cell line.Some PGs(NG2/CSPG4,CSPG5,and versican)contributed to the molecular heterogeneity of these cells being cell line-specifically expressed in all cell lines,which also differed in terms of the CS/HS content.Transcriptional activity of the HS metabolic system was low in these GB cell lines,expressing mainly EXT1/2 and NDST1/2,while expression levels of sulfotransferases and SULF2 were cell line-specific.TMZ resistance of these cells was correlated with the expression of stem-cell marker CD44(+3.5-fold,r=0.73)and GR(-3-fold,r=-0.81).TMZ treatment of the resistant(LN405)and sensitive(LN215)cells resulted in complex changes in cell migration as well as NG2/CSPG4 expression and CS/HS content.Conclusion:Differential expression of PGs and CS/HS content contribute to the heterogeneity of GB cells,and CD44 and NR3C1 might be informative biomarkers for TMZ resistance.