Characterization of glypican-5 and chromosomal localization of human GPC5, a new member of the glypican gene family

Integrated analysis of plasma proteome and cortex single-cell transcriptome reveals the novel biomarkers during cortical aging

Background

With the increase of age, multiple physiological functions of people begin gradually degenerating. Regardless of natural aging or pathological aging, the decline in cognitive function is one of the most obvious features in the process of brain aging. Brain aging is a key factor for several neuropsychiatric disorders and for most neurodegenerative diseases characterized by onset typically occurring late in life and with worsening of symptoms over time. Therefore, the early prevention and intervention of aging progression are particularly important. Since there is no unified conclusion about the plasma diagnostic biomarkers of brain aging, this paper innovatively employed the combined multi-omics analysis to delineate the plasma markers of brain aging.

Methods

In order to search for specific aging markers in plasma during cerebral cortex aging, we used multi-omics analysis to screen out differential genes/proteins by integrating two prefrontal cortex (PFC) single-nucleus transcriptome sequencing (snRNA-seq) datasets and one plasma proteome sequencing datasets. Then plasma samples were collected from 20 young people and 20 elder people to verify the selected differential genes/proteins with ELISA assay.

Results

We first integrated snRNA-seq data of the post-mortem human PFC and generated profiles of 65,064 nuclei from 14 subjects across adult (44-58 years), early-aging (69-79 years), and late-aging (85-94 years) stages. Seven major cell types were classified based on established markers, including oligodendrocyte, excitatory neurons, oligodendrocyte progenitor cells, astrocytes, microglia, inhibitory neurons, and endotheliocytes. A total of 93 cell-specific genes were identified to be significantly associated with age. Afterward, plasma proteomics data from 2,925 plasma proteins across 4,263 young adults to nonagenarians (18-95 years old) were combined with the outcomes from snRNA-seq data to obtain 12 differential genes/proteins (GPC5, CA10, DGKB, ST6GALNAC5, DSCAM, IL1RAPL2, TMEM132C, VCAN, APOE, PYH1R, CNTN2, SPOCK3). Finally, we verified the 12 differential genes by ELISA and found that the expression trends of five biomarkers (DSCAM, CNTN2, IL1RAPL2, CA10, GPC5) were correlated with brain aging.

Conclusion

Five differentially expressed proteins (DSCAM, CNTN2, IL1RAPL2, CA10, GPC5) can be considered as one of the screening indicators of brain aging, and provide a scientific basis for clinical diagnosis and intervention.

Prognostic value of GPC5 polymorphism rs2352028 and clinical characteristics in Chinese lung cancer patients

Background: GPC5 rs2352028 is associated with the risk of lung cancer, but its relationship with lung cancer prognosis is unclear. Materials & methods: The authors collected blood samples from 888 patients with lung cancer and used a Cox proportional hazards model to analyze the association between prognosis and GPC5 polymorphism rs2352028. Results: GPC5 rs2352028 C > T was associated with a better prognosis. Patients with CT genotype had longer overall survival than those with CC genotype. Additionally, older and early-stage patients with CT + TT genotype had a lower risk of death than those with CC genotype. Conclusion: GPC5 rs2352028 C > T may play a protective role in patients with lung cancer and GPC5 rs2352028 may be a potential genetic marker for lung cancer prognosis.

GPC5 suppresses lung cancer progression and metastasis via intracellular CTDSP1/AhR/ARNT signaling axis and extracellular exosome secretion

Lung cancer is the leading cause of cancer-related death worldwide. Glypican-5 (GPC5) is a member of heparan sulfate proteoglycans, and its biological importance in initiation and progression of lung cancer remains controversial. In the present study, we revealed that GPC5 transcriptionally enhanced the expression of CTDSP1 (miR-26b host gene) via AhR-ARNT pathway, and such up-regulation of CTDSP1 intracellularly contributed to the inhibited proliferation of lung cancer cells. Moreover, exosomes derived from GPC5-overexpressing human lung cancer cells (GPC5-OE-derived exosomes) had an extracellular repressive effect on human lymphatic endothelial cells (hLECs), leading to decreased tube formation and migration. Comparison between GPC5-WT- and GPC5-OE-derived exosomes showed that miR-26b (embedded within introns of CTDSP1 gene) was significantly up-regulated in GPC5-OE-derived exosomes and critical to the influence on hLECs. On the mechanism, we demonstrated that miR-26b transferred into hLECs directly targeted to PTK2 3'-UTR and led to PTK2 down-regulation, resulting in defects in tube formation and migration of hLECs. By uncovering the regulation network among GPC5, miR-26b, miR-26b host gene (CTDSP1), and target gene (PTK2), our findings demonstrated that GPC5 functioned as a tumor suppressor in human lung cancer.

Distinct diagnostic and prognostic values of Glypicans gene expression in patients with hepatocellular carcinoma

Backgroud

In our current work, we aimed to investigate the expressions of glypican (GPC) family genes at the mRNA level and assess their prognostic significances in patients with hepatocellular carcinoma (HCC).

Methods

The pathological roles of GPC family genes were examined using bioinformatics analysis. The diagnostic values of GPC genes were explored with the Gene Expression Profiling Interactive Analysis. Moreover, the mRNA expression and prognostic values of GPC genes were assessed via the KM plotter database.

Results

Our data showed that the expression of GPC-3 was dramatically increased in the liver tumor tissue. Moreover, the expressions of the other five GPC family members were not significantly different between the tumor and normal liver tissues (P > 0.05). Furthermore, the up-regulation of GPC-1 at the mRNA level was dramatically correlated to the reduced overall survival (OS) for all HCC patients (hazard ratio = 2.03, 95% confidence intervals =1.44–2.87, P = 4.1e-05) compared with its low-expression group. Besides, the prognosis of the Caucasians was related to most GPC family genes, while the prognosis of the Asian race was only related to the expression of GPC-2. Besides, for pathological factors, including stage, grade, AJCC, and vascular invasion, the higher the pathological grade and vascular invasiveness, the lower the expression levels of GPC family genes (P < 0.05). Finally, the expression levels of GPC-1, 2, and 3 in the hepatitis group were related to the poor prognosis of HCC in the risk factor (alcohol consumption and hepatitis) subgroup (P < 0.05).

Conclusions

Our findings indicated that GPC-3 was dysregulated in HCC compared with paracancerous tissues. The expression of GPC-1 could be used as a potent predictive index for the general prognosis of HCC. The pathology, patients, and risk factors might affect the prognostic value of GPC family genes in HCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08104-z.

Glypicans and Heparan Sulfate in Synaptic Development, Neural Plasticity, and Neurological Disorders

Heparan sulfate proteoglycans (HSPGs) are components of the cell surface and extracellular matrix, which bear long polysaccharides called heparan sulfate (HS) attached to the core proteins. HSPGs interact with a variety of ligand proteins through the HS chains, and mutations in HSPG-related genes influence many biological processes and cause various diseases. In particular, recent findings from vertebrate and invertebrate studies have raised the importance of glycosylphosphatidylinositol-anchored HSPGs, glypicans, as central players in the development and functions of synapses. Glypicans are important components of the synapse-organizing protein complexes and serve as ligands for leucine-rich repeat transmembrane neuronal proteins (LRRTMs), leukocyte common antigen-related (LAR) family receptor protein tyrosine phosphatases (RPTPs), and G-protein-coupled receptor 158 (GPR158), regulating synapse formation. Many of these interactions are mediated by the HS chains of glypicans. Neurexins (Nrxs) are also synthesized as HSPGs and bind to some ligands in common with glypicans through HS chains. Therefore, glypicans and Nrxs may act competitively at the synapses. Furthermore, glypicans regulate the postsynaptic expression levels of ionotropic glutamate receptors, controlling the electrophysiological properties and non-canonical BMP signaling of synapses. Dysfunctions of glypicans lead to failures in neuronal network formation, malfunction of synapses, and abnormal behaviors that are characteristic of neurodevelopmental disorders. Recent human genetics revealed that glypicans and HS are associated with autism spectrum disorder, neuroticism, and schizophrenia. In this review, we introduce the studies showing the roles of glypicans and HS in synapse formation, neural plasticity, and neurological disorders, especially focusing on the mouse and Drosophila as potential models for human diseases.

Heparan Sulfate Proteoglycans Biosynthesis and Post Synthesis Mechanisms Combine Few Enzymes and Few Core Proteins to Generate Extensive Structural and Functional Diversity

Glycosylation is a common and widespread post-translational modification that affects a large majority of proteins. Of these, a small minority, about 20, are specifically modified by the addition of heparan sulfate, a linear polysaccharide from the glycosaminoglycan family. The resulting molecules, heparan sulfate proteoglycans, nevertheless play a fundamental role in most biological functions by interacting with a myriad of proteins. This large functional repertoire stems from the ubiquitous presence of these molecules within the tissue and a tremendous structural variety of the heparan sulfate chains, generated through both biosynthesis and post synthesis mechanisms. The present review focusses on how proteoglycans are “gagosylated” and acquire structural complexity through the concerted action of Golgi-localized biosynthesis enzymes and extracellular modifying enzymes. It examines, in particular, the possibility that these enzymes form complexes of different modes of organization, leading to the synthesis of various oligosaccharide sequences.

Effect of genetic polymorphisms on therapeutic response in multiple sclerosis relapsing-remitting patients treated with interferon-beta

Treatment with interferon beta (IFNβ) is one of the first-line treatments for multiple sclerosis. In clinical practice, however, many patients present suboptimal response to IFNβ, with the proportion of non-responders ranging from 20 to 50%. This variable response can be affected by genetic factors, such as polymorphisms in the genes involved in the disease state, pharmacodynamics, metabolism or in the action mechanism of IFNβ, which can affect the efficacy of this drug. This review assesses the impact of pharmacogenetics studies on response to IFNβ treatment among patients diagnosed with relapsing-remitting multiple sclerosis (RRMS). The results suggest that the detection of polymorphisms in several genes (CD46, CD58, FHIT, IRF5, GAPVD1, GPC5, GRBRB3, MxA, PELI3 and ZNF697) could be used in the future as predictive markers of response to IFNβ treatment in patients diagnosed with RRMS. However, few studies have been carried out and they have been performed on small sample sizes, which makes it difficult to generalize the role of these genes in IFNβ treatment. Studies on large sample sizes with longer term follow-up are therefore required to confirm these results.

The Role of Glypicans in Cancer Progression and Therapy

Glypicans are a family of heparan sulfate proteoglycans that are attached to the cell membrane via a glycosylphosphatidylinositol anchor. Glypicans interact with multiple ligands, including morphogens, growth factors, chemokines, ligands, receptors, and components of the extracellular matrix through their heparan sulfate chains and core protein. Therefore, glypicans can function as coreceptors to regulate cell proliferation, cell motility, and morphogenesis. In addition, some glypicans are abnormally expressed in cancers, possibly involved in tumorigenesis, and have the potential to be cancer-specific biomarkers. Here, we provide a brief review focusing on the expression of glypicans in various cancers and their potential to be targets for cancer therapy.

The Role of Cell Growth-Related Gene Copy Number Variation in Autoimmune Thyroid Disease

Autoimmune thyroid disease (AITD) is a recurrent and refractory clinical endocrine disease. Some studies have shown that the incidence of AITD is not only related to iodine, a kind of environmental factor, but that susceptibility genes also play a crucial role in its pathogenesis. Since research on susceptibility genes is still underway, the aims of this study were to assess the association between copy number variations (CNVs) and AITD, to identify genes related to susceptibility to AITD, and to explore the risk factors in the occurrence of AITD. Blood samples from five AITD patients and five controls from each area were assessed by chromosome microarray to identify candidate genes. The copy number (CN) of the candidate genes and urinary iodine levels were determined in adults, including 158 AITD patients and 181 controls, from areas having different iodine statuses. The cell growth-related genes, glypican 5 (GPC5), B9 domain containing 2 (B9D2), and ankyrin repeat and suppressor of cytokine signaling [SOCS] box-containing protein family 11 (ASB11), were selected as the candidate genes. The distribution of GPC5, B9D2, and ASB11 CNVs in AITD patients and controls was significantly different, and high urinary iodine levels and GPC5 CNVs are risk factors for AITD. There was no significant association between urinary iodine level and CNVs of the candidate genes. High urinary iodine levels and GPC5 CNVs are risk factors for AITD, but an association with the occurrence of AITD was not found.

Analysis of chosen SNVs in GPC5, CD58 and IRF8 genes in multiple sclerosis patients

PURPOSE

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system with a neurodegenerative compound. Heterogenetic background of autoimmunity pathway components has been suggested in the MS pathogenesis. The main aim of our study was to evaluate the association between selected polymorphisms of theCD58, IRF8 and GPC5 genes and treatment effectiveness in a group of relapsing-remitting MS patients. This is the first study of MS patients from Podlaskie Region in the Polish population.

MATERIALS AND METHODS

The study group comprised 174 relapsing-remitting MS patients diagnosed under 40 years of age. Genotyping was performed using ready to use TaqMan assays.

RESULTS

We demonstrate a strong association of the polymorphisms with sex, age of onset and response to the treatment applied. A significant correlation was observed in the presence of allele T of rs10492503 polymorphism inGPC5 gene with sex and age of MS onset. Logistic regression analysis revealed an increased risk of the interaction of rs17445836 in IRF8 gene with male sex and the type of treatment (OR = 3.80, p < 0.05), and a decreased risk in the interaction of female sex with disease progress according to the EDSS scale (OR=-2.33, p < 0.05).

CONCLUSIONS

The analysis of the correlation between different alleles, genotypes and clinical status confirmed the interaction between the genetic factors of age of onset and response to therapy. The study suggests that genetic variants inGPC5, CD58 and IRF8 genes may be of clinical interest in MS as predictors of age of onset and response to therapy.

MicroRNA-301b promotes the proliferation and invasion of glioma cells through enhancing activation of Wnt/β-catenin signaling via targeting Glypican-5

Accumulating evidence has suggested that Glypican-5 (GPC5) is a tumor suppressor gene in many types of cancers. However, whether GPC5 is involved in glioma remains unknown. This study was designed to explore the expression, biological function and regulatory mechanism of GPC5 in glioma. Our results demonstrated that GPC5 expression was significantly decreased in multiple glioma cell lines. Gain-of-function experiments showed that the ectopic expression of GPC5 markedly inhibited the proliferation, invasion and Wnt/β-catenin signaling of glioma cell lines. GPC5 was identified as a target gene of microRNA-301b (miR-301b). Further data showed that miR-301b expression was significantly up-regulated in glioma tissues and cell lines. In addition, miR-301b expression was inversely correlated with GPC5 expression in clinical glioma tissues. The overexpression of miR-301b promoted the proliferation, invasion and Wnt/β-catenin signaling of glioma cell lines, whereas the inhibition of miR-301b showed the opposite effect. However, the silencing of GPC5 significantly reversed the antitumor effect of miR-301b inhibition. Overall, our results revealed a tumor suppressive role of GPC5 in glioma and suggested that GPC5 expression was regulated by miR-301b. Our study indicates that the inhibition of miR-301b represses the proliferation and invasion of glioma cells by up-regulating GPC5 expression.

Polyclonal antibody production against rGPC3 and their application in diagnosis of hepatocellular carcinoma

Glypican-3 (GPC3) is an integral membrane proteoglycan, which contains a core protein anchored to the cytoplasmic membrane through a glycosylphosphatidylinositol linkage. The glypican-3 can regulate the signaling pathways, thereby enhances cell division, growth, and apoptosis in certain cell types. It is almost nonexistent on the surface of the human normal cell membrane and highly expresses on the membrane of hepatocellular carcinoma (HCC) cells. It has been well established that GPC3 provides a useful diagnostic marker. For generating the polyclonal antibody of GPC3, we expected that GPC3 N-terminal region (amino acid sequence 26-358) could be expressed in Escherichia coli system, however, no active expression was observed after IPTG induction. Interestingly, after deletion of six proline residues from position 26 to 31 in the N-terminus, expression of recombinant GPC3 was clearly detected. We further analyzed the expressed protein deprived of six prolines, to immunize the New Zealand male rabbits for production of active antibodies. The binding affinity of antibody was analyzed by immunofluorescence analysis, immunohistochemical detection, and western blotting. The functional GPC3 N-terminal protein recombinant development, expression, purification, and the polyclonal antibody have been generated provide the basis for the diagnosis of HCC in cancer therapy.

Evaluating clinical and prognostic implications of Glypican-3 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most deadly cancers worldwide. In patients with HCC, histopathogical differentiation is an important indicator of prognosis; however, because determination of HCC differentiation is difficult, the recently described immunohistochemical (IHC) marker glypican3 (GPC3) might assist in HCC prognostication.The goal of our study was to investigate GPC3's IHC staining pattern and define the relationship between its expression and patients' clinicopathologic features and overall survival. We retrieved clinical parameters from 101 pathologically diagnosed HCC patients' medical records and classified these patients into 4 clinical score categories (0–3) based on increasing GPC3 staining intensity and the percentage of stained tumor cells in their resection and biopsy specimens. Histopathological samples were well, moderately, and poorly differentiated in 33, 22, and 12 patients, respectively, and the GPC3 expression rate was 63%, 86%, and 92%,respectively. The median overall survival was 49.9 months (confidence interval (CI): 35.3–64.6 months) for clinical scores 0–1 and 30.7 months (CI: 19.4–41.9 months) for clinical scores 2–3. This difference was not statistically significant (P = .06) but showed a strong trend. In conclusion, a greater GPC3 expression is associated with a worse HCC prognosis and may be a promising prognostic marker.

The heparanase/heparan sulfate proteoglycan axis: A potential new therapeutic target in sarcomas

Heparanase, the only known mammalian endoglycosidase degrading heparan sulfate (HS) chains of HS proteoglycans (HSPG), is a highly versatile protein affecting multiple events in tumor cells and their microenvironment. In several malignancies, deregulation of the heparanase/HSPG system has been implicated in tumor progression, hence representing a valuable therapeutic target. Currently, multiple agents interfering with the heparanase/HSPG axis are under clinical investigation. Sarcomas are characterized by a high biomolecular complexity and multiple levels of interconnection with microenvironment sustaining their growth and progression. The clinical management of advanced diseases remains a challenge. In several sarcoma subtypes, high levels of heparanase expression have been correlated with poor prognosis associated factors. On the other hand, expression of cell surface-associated HSPGs (i.e. glypicans and syndecans) has been found altered in specific sarcoma subtypes. Recent studies provided the preclinical proof-of-principle of the role of the heparanase/HSPG axis as therapeutic target in various sarcoma subtypes. Although currently there are no clinical trials evaluating agents targeting heparanase and/or HSPGs in sarcomas, we here provide arguments for this strategy as potentially able to implement the therapeutic options for sarcoma patients.

miR-297 acts as an oncogene by targeting GPC5 in lung adenocarcinoma

OBJECTIVES

Emerging studies have demonstrated that microRNAs (miRNAs) play crucial roles in carcinogenesis of many developing human tumours. However, the functions and mechanisms of miR-297 in lung cancer have, up to now, been largely undefined.

MATERIALS AND METHODS

Here, miR-297 expression was measured in lung adenocarcinoma tissues and cell lines, using qRT-PCR. Lung adenocarcinoma cell line was treated with an miR-297 mimic. MTT and colony analysis were performed to detect cell proliferation and colony formation. The direct target gene of miR-297 was assessed by qRT-PCR, Western blotting and luciferase assays.

RESULTS

We demonstrated that miR-297 expression was upregulated in lung adenocarcinomas compared to adjacent normal tissues. Expression of miR-297 was also upregulated in tested lung adenocarcinoma cell lines. Ectopic expression of miR-297 enhanced lung adenocarcinoma cell proliferation and colony formation. Furthermore, overexpression of miR-297 promoted cell migration and invasion. In addition, we identified Glypican-5 (GPC5) as a direct target gene of miR-297 in lung adenocarcinoma cells. Expression of GPC5 was downregulated in both lung adenocarcinoma tissues and cell lines. Moreover, expression of GPC5 was inversely associated with expression of miR-297 in lung adenocarcinoma tissues.

CONCLUSIONS

These results suggest that miR-297 acted as an oncogenic miRNA, partly by targeting GPC5, adenocarcinoma of the lung.

Glypican-5 is a tumor suppressor in non-small cell lung cancer cells

Glypican-5 (GPC5) belongs to the glypican family of proteoglycans that have been implicated in a variety of physiological processes, ranging from cell proliferation to morphogenesis. However, the role of GPC5 in human cancer remains poorly understood. We report that knockdown of GPC5 in bronchial epithelial cells promoted, and forced expression of GPC5 in non-small lung cancer (NSCLC) cells suppressed, the anchorage-independent cell growth. In vivo, expression of GPC5 inhibited xenograft tumor growth of NSCLC cells. Furthermore, we found that GPC5 was expressed predominantly as a membrane protein, and its expression led to diminished phosphorylation of several oncogenic receptor tyrosine kinases, including the ERBB family members ERBB2 and ERBB3, which play critical roles in lung tumorigenesis. Collectively, our results suggest that GPC5 may act as a tumor suppressor, and reagents that activate GPC5 may be useful for treating NSCLC.

•

GPC5 suppresses anchorage-independent growth of lung cancer cells.

•

GPC5 suppresses xenograft growth of lung cancer cells.

•

GPC5 is localized to the membrane and suppresses oncogenic RTKs.

Glypican-3 is a biomarker and a therapeutic target of hepatocellular carcinoma

BACKGROUND

The carcinogenesis of hepatocellular carcinoma (HCC) is a multi-factorial, multi-step and complex process. Early diagnosis and effective treatments are of utmost importance. This review summarized the recent studies of oncofetal glypican-3 (GPC-3), a membrane-associated heparan sulfate proteoglycan, in the diagnosis and treatment of HCC.

DATA SOURCES

English-language reports published from June 2001 to September 2014 were searched from MEDLINE. The key words searched included: GPC-3, biomarker, target and HCC. The sensitivity, specificity, positive and negative predictive values were extracted, and the effect of GPC-3 targeted therapy on HCC was also evaluated.

RESULTS

GPC-3 plays a crucial role in HCC cell proliferation and metastasis. It mediates oncogenesis involving signaling pathways during hepatocyte malignant transformation. GPC-3 expression is increased in atypical hyperplasia and cancerous tissues. GPC-3 levels in HCC patients are related to HBV infection, TNM stage, periportal cancerous embolus, and extrahepatic metastasis. The diagnostic accuracy of the combination of serum GPC-3 and alpha-fetoprotein in HCC is up to 94.3%. Down-regulation of GPC-3 with specific siRNA or anti-GPC-3 antibody alters cell migration, metastasis and invasion behaviors. The nude mice xenograft tumor growth is inhibited by silencing GPC-3 gene transcription.

CONCLUSION

Oncofetal GPC-3 is a highly specific biomarker for the diagnosis of HCC and a promising target molecule for HCC gene therapy.

Classification of non-small cell lung cancer based on copy number alterations

Lung cancer is one of the leading causes of cancer mortality worldwide and non–small cell lung cancer (NSCLC) accounts for the most part. NSCLC can be further divided into adenocarcinoma (ACA) and squamous cell carcinoma (SCC). It is of great value to distinguish these two subgroups clinically. In this study, we compared the genome-wide copy number alterations (CNAs) patterns of 208 early stage ACA and 93 early stage SCC tumor samples. As a result, 266 CNA probes stood out for better discrimination of ACA and SCC. It was revealed that the genes corresponding to these 266 probes were enriched in lung cancer related pathways and enriched in the chromosome regions where CNA usually occur in lung cancer. This study sheds lights on the CNA study of NSCLC and provides some insights on the epigenetic of NSCLC.

The overexpression of glypican-5 promotes cancer cell migration and is associated with shorter overall survival in non-small cell lung cancer

Although the correlation between glypican-5 (GPC5) and lung cancer is well known, the effect of GPC5 expression on non-small cell lung cancer (NSCLC) survival remains to be determined. In the present study, GPC5 expression in A549, H3255, and SPC-A1 NSCLC cell lines was evaluated by reverse transcription-polymerase chain reaction (RT-PCR) and western blot analysis. GPC5 mRNA and protein expression levels were found to be higher in A549 and H3255 cells compared with SPC-A1 cells. The role of GPC5 in NSCLC cell migration was evaluated in vitro by shRNA-mediated knockdown or the overexpression of GPC5 through scratch and transwell assays. The mean migration rates of cancer cells transfected with pRNAT-shRNA-GPC5-1 were reduced compared with the controls in A549 (P<0.001) and H3255 (P=0.001), while the migration rate of SPC-A1 with GPC5 overexpression was higher than that of the control (P=0.001). The downregulation of GPC5 impeded the transmigration of A549 and H3255 while the upregulation of GPC5 expression promoted the transmembrane invasion of SPC-A1. Furthermore, a panel of formalin-fixed paraffin-embedded NSCLC tissues from 127 patients undergoing curative resection (stages I, II and III) between January, 2003 and December, 2008 were obtained in order to investigate the correlation between GPC5 expression and clinicopathological factors using immunohistochemical methods. The results demonstrated that high GPC5 expression levels in NSCLC were associated with respiratory symptoms in lung cancer diagnosis, poor differentiation, vascular invasion, regional lymph node metastasis and a higher TNM stage. Using the Kaplan-Meier method, NSCLC patients with high levels of GPC5 expression demonstrated a significantly shorter overall survival time compared with those with low GPC5 expression levels (median postsurgical survival time: 14.0 months vs. 59.0 months, P=0.001). GPC5 expression was also identified as an independent prognostic factor by Cox regression analysis [adjusted hazard ratio: 2.18; 95% confidence interval (CI): 1.35–3.52; P=0.001]. This study suggested that increased levels of GPC5 expression are a poor prognostic marker for NSCLC.

Multiple sclerosis: individualized disease susceptibility and therapy response

Multiple sclerosis (MS) is a heterogeneous disease in which diverse genetic, pathological and clinical backgrounds lead to variable therapy response. Accordingly, MS care should be tailored to address disease traits unique to each person. At the core of personalized management is the emergence of new knowledge, enabling optimized treatment and disease-modifying therapies. This overview analyzes the promise of genetic and nongenetic biomarkers in advancing decision-making algorithms to assist diagnosis or in predicting the disease course and therapy response in any given MS patient.

Single nucleotide polymorphisms in multiple sclerosis: disease susceptibility and treatment response biomarkers

Multiple sclerosis (MS) is a chronic inflammatory demyelinating and neurodegenerative disease of the central nervous system characterized by unpredictable and variable clinical course. Etiology of MS involves both genetic and environmental factors. New technologies identified genetic polymorphisms associated with MS susceptibility among which immunologically relevant genes are significantly overrepresented. Although individual genes contribute only a small part to MS susceptibility, they might be used as biomarkers, thus helping to identify accurate diagnosis, predict clinical disease course and response to therapy. This review focuses on recent progress in research on MS genetics with special emphasis on the possibility to use single nucleotide polymorphism of candidate genes as biomarkers of susceptibility to disease and response to therapy.

Therapeutic potential of targeting glypican-3 in hepatocellular carcinoma

Glypican-3 (GPC3) is a developmentally-regulated oncofetal protein that has been established as a clinically-relevant biomarker for early hepatocellular carcinoma (HCC). It is one of the first transcripts to appear during malignant hepatocyte transformation, and is expressed at the protein level in approximately half of high-grade dysplastic macronodules in cirrhotic liver. Several studies show it is expressed in most (75 to 100%) of HCCs confirmed by histopathology. The protein is anchored to the hepatocyte membrane by a glycosyl-phosphatidylinositol (GPI) anchor and shows consistent membrane immunostaining pattern, making it a viable target for immunotherapeutic approaches. Targeting GPC3 for therapeutic intervention is a promising approach for the clinical management of HCC and selected other tumors that express the marker.

Points of therapeutic intervention along the Wnt signaling pathway in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the third leading cause of cancer mortality worldwide. However, there is little known about targeted therapeutics for the treatment of this devastating tumor. Among the growth factor signaling cascades deregulated in HCC, evidences suggest that the WNT/Frizzled-mediated signaling pathway plays a key role in the hepatic carcinogenesis. Aberrant activation of the signaling in HCC is mostly due to deregulated expression of the Wnt/β-catenin signaling components. This leads to the activation of the β-catenin/TCF dependent target genes, which controls cell proliferation, cell cycle, apoptosis or motility. It has been shown that disruption of the Wnt/β-catenin signaling cascade displayed anti-cancer properties in HCC. Currently, no therapeutic molecules targeting the WNT pathway are available or under clinical evaluation for the treatment of HCC. This review will discuss the identified potential molecular targets related to the canonical WNT signaling pathway and their potential therapeutic usefulness.

Lung cancer in never smokers

Lung cancer in never smokers (LCINS) has lately been recognized as a unique disease based on rapidly gained knowledge from genomic changes to treatment responses. The focus of this article is on current knowledge and challenges with regard to LCINS expanded from recent reviews highlighting five areas: (1) distribution of LCINS by temporal trends, geographic regions, and populations; (2) three well-recognized environmental risk factors; (3) other plausible environmental risk factors; (4) prior chronic lung diseases and infectious diseases as risk factors; and (5) lifestyles as risk or protective factors. This article will also bring attention to recently published literature in two pioneering areas: (1) histological characteristics, clinical features with emerging new effective therapies, and social and psychological stigma; and (2) searching for susceptibility genes using integrated genomic approaches.

Common variation in GPC5 is associated with acquired nephrotic syndrome

Severe proteinuria is a defining factor of nephrotic syndrome irrespective of the etiology. Investigation of congenital nephrotic syndrome has shown that dysfunction of glomerular epithelial cells (podocytes) plays a crucial role in this disease. Acquired nephrotic syndrome is also assumed to be associated with podocyte injury. Here we identify an association between variants in GPC5, encoding glypican-5, and acquired nephrotic syndrome through a genome-wide association study and replication analysis (P value under a recessive model (P(rec)) = 6.0 × 10(-11), odds ratio = 2.54). We show that GPC5 is expressed in podocytes and that the risk genotype is associated with higher expression. We further show that podocyte-specific knockdown and systemic short interfering RNA injection confers resistance to podocyte injury in mouse models of nephrosis. This study identifies GPC5 as a new susceptibility gene for nephrotic syndrome and implicates GPC5 as a promising therapeutic target for reducing podocyte vulnerability in glomerular disease.

Glypican-3: a new target for cancer immunotherapy

Hepatocellular carcinoma (HCC) remains a common malignant cancer worldwide. There is an urgent need to identify new molecular targets for the development of novel therapeutic approaches. Herein, we review the structure, function and biology of glypican-3 (GPC3) and its role in human cancer with a focus on its potential as a therapeutic target for immunotherapy. GPC3 is a cell-surface protein that is over-expressed in HCC. Loss-of-function mutations of GPC3 cause Simpson-Golabi-Behmel syndrome (SGBS), a rare X-linked overgrowth condition. GPC3 binds Wnt and Hedgehog (Hh) signalling proteins. GPC3 is also able to bind basic growth factors such as fibroblast growth factor 2 through its heparan sulphate glycan chains. GPC3 is a promising candidate for liver cancer therapy given that it shows high expression in HCC. An anti-GPC3 monoclonal antibody has shown anti-cancer activity in mice and its humanised IgG molecule is currently undergoing clinical evaluation in patients with HCC. There is also evidence that soluble GPC3 may be a useful serum biomarker for HCC.

Multiple sclerosis susceptibility alleles in African Americans

Multiple sclerosis (MS) is an autoimmune demyelinating disease characterized by complex genetics and multifaceted gene-environment interactions. Compared to whites, African Americans have a lower risk for developing MS, but African Americans with MS have a greater risk of disability. These differences between African Americans and whites may represent differences in genetic susceptibility and/or environmental factors. SNPs from 12 candidate genes have recently been identified and validated with MS risk in white populations. We performed a replication study using 918 cases and 656 unrelated controls to test whether these candidate genes are also associated with MS risk in African Americans. CD6, CLEC16a, EVI5, GPC5, and TYK2 contained SNPs that are associated with MS risk in the African American data set. EVI5 showed the strongest association outside the major histocompatibility complex (rs10735781, OR=1.233, 95% CI=1.06-1.43, P-value=0.006). In addition, RGS1 seems to affect age of onset whereas TNFRSF1A seems to be associated with disease progression. None of the tested variants showed results that were statistically inconsistent with the effects established in whites. The results are consistent with shared disease genetic mechanisms among individuals of European and African ancestry.

Genetic variants and risk of lung cancer in never smokers: a genome-wide association study

BACKGROUND

Lung cancer in individuals who have never smoked tobacco products is an increasing medical and public-health issue. We aimed to unravel the genetic basis of lung cancer in never smokers.

METHODS

We did a four-stage investigation. First, a genome-wide association study of single nucleotide polymorphisms (SNPs) was done with 754 never smokers (377 matched case-control pairs at Mayo Clinic, Rochester, MN, USA). Second, the top candidate SNPs from the first study were validated in two independent studies among 735 (MD Anderson Cancer Center, Houston, TX, USA) and 253 (Harvard University, Boston, MA, USA) never smokers. Third, further replication of the top SNP was done in 530 never smokers (UCLA, Los Angeles, CA, USA). Fourth, expression quantitative trait loci (eQTL) and gene-expression differences were analysed to further elucidate the causal relation between the validated SNPs and the risk of lung cancer in never smokers.

FINDINGS

44 top candidate SNPs were identified that might alter the risk of lung cancer in never smokers. rs2352028 at chromosome 13q31.3 was subsequently replicated with an additive genetic model in the four independent studies, with a combined odds ratio of 1.46 (95% CI 1.26-1.70, p=5.94x10(-6)). A cis eQTL analysis showed there was a strong correlation between genotypes of the replicated SNPs and the transcription level of the gene GPC5 in normal lung tissues (p=1.96x10(-4)), with the high-risk allele linked with lower expression. Additionally, the transcription level of GPC5 in normal lung tissue was twice that detected in matched lung adenocarcinoma tissue (p=6.75x10(-11)).

INTERPRETATION

Genetic variants at 13q31.3 alter the expression of GPC5, and are associated with susceptibility to lung cancer in never smokers. Downregulation of GPC5 might contribute to the development of lung cancer in never smokers.

FUNDING

US National Institutes of Health; Mayo Foundation.

Heparan sulfate proteoglycans: structure, protein interactions and cell signaling

Heparan sulfate proteoglycans are ubiquitously found at the cell surface and extracellular matrix in all the animal species. This review will focus on the structural characteristics of the heparan sulfate proteoglycans related to protein interactions leading to cell signaling. The heparan sulfate chains due to their vast structural diversity are able to bind and interact with a wide variety of proteins, such as growth factors, chemokines, morphogens, extracellular matrix components, enzymes, among others. There is a specificity directing the interactions of heparan sulfates and target proteins, regarding both the fine structure of the polysaccharide chain as well precise protein motifs. Heparan sulfates play a role in cellular signaling either as receptor or co-receptor for different ligands, and the activation of downstream pathways is related to phosphorylation of different cytosolic proteins either directly or involving cytoskeleton interactions leading to gene regulation. The role of the heparan sulfate proteoglycans in cellular signaling and endocytic uptake pathways is also discussed.

Glypicans

The glypican family of cell-surface heparan sulfate proteoglycans modulate the actions of many developmentally important signal proteins.

Glypicans are heparan sulfate proteoglycans that are bound to the outer surface of the plasma membrane by a glycosyl-phosphatidylinositol anchor. Homologs of glypicans are found throughout the Eumetazoa. There are six family members in mammals (GPC1 to GPC6). Glypicans can be released from the cell surface by a lipase called Notum, and most of them are subjected to endoproteolytic cleavage by furin-like convertases. In vivo evidence published so far indicates that the main function of membrane-attached glypicans is to regulate the signaling of Wnts, Hedgehogs, fibroblast growth factors and bone morphogenetic proteins (BMPs). Depending on the context, glypicans may have a stimulatory or inhibitory activity on signaling. In the case of Wnt, it has been proposed that the stimulatory mechanism is based on the ability of glypicans to facilitate and/or stabilize the interaction of Wnts with their signaling receptors, the Frizzled proteins. On the other hand, GPC3 has recently been reported to inhibit Hedgehog protein signaling during development by competing with Patched, the Hedgehog receptor, for Hedgehog binding. Surprisingly, the regulatory activity of glypicans in the Wnt, Hedgehog and BMP signaling pathways is only partially dependent on the heparan sulfate chains.

Role for amplification and expression of glypican-5 in rhabdomyosarcoma

Overexpression of genes, through genomic amplification and other mechanisms, can critically affect the behavior of tumor cells. Genomic amplification of the 13q31-32 region is reported in many tumors, including rhabdomyosarcomas that are primarily pediatric sarcomas resembling developing skeletal muscle. The minimum overlapping region of amplification at 13q31-32 in rhabdomyosarcomas was defined as containing two genes: Glypican-5 (GPC5) encoding a cell surface proteoglycan and C13orf25 encompassing the miR-17-92 micro-RNA cluster. Genomic copy number and gene expression analyses of rhabdomyosarcomas indicated that GPC5 was the only gene consistently expressed and up-regulated in all cases with amplification. Constitutive overexpression and knockdown of GPC5 expression in rhabdomyosarcoma cell lines increased and decreased cell proliferation, respectively. A correlation between expression levels of nascent pre-rRNA and GPC5 (P = 0.001), but not a C13orf25 transcript containing miR-17-92, in primary samples supports an association of GPC5 with proliferative capacity in vivo. We show that GPC5 increases proliferation through potentiating the action of the growth factors fibroblast growth factor 2 (FGF2), hepatocyte growth factor (HGF), and Wnt1A. GPC5 enhanced the intracellular signaling of FGF2 and HGF and altered the cellular distribution of FGF2. The mesoderm-inducing effect of FGF2 and FGF4 in Xenopus blastocysts was also enhanced. Our data are consistent with a role of GPC5, in the context of sarcomagenesis, in enhancing FGF signaling that leads to mesodermal cell proliferation without induction of myogenic differentiation. Furthermore, the properties of GPC5 make it an attractive target for therapeutic intervention in rhabdomyosarcomas and other tumors that amplify and/or overexpress the gene.

New locus for autosomal dominant mitral valve prolapse on chromosome 13: clinical insights from genetic studies

BACKGROUND

Mitral valve prolapse (MVP) is a common disorder associated with mitral regurgitation, endocarditis, heart failure, and sudden death. To date, 2 MVP loci have been described, but the defective genes have yet to be discovered. In the present study, we analyzed a large family segregating MVP, and identified a new locus, MMVP3. This study and others have enabled us to explore mitral valve morphological variations of currently uncertain clinical significance.

METHODS AND RESULTS

Echocardiograms and blood samples were obtained from 43 individuals who were classified by the extent and pattern of displacement. Genotypic analyses were performed with polymorphic microsatellite markers. Evidence of linkage was obtained on chromosome 13q31.3-q32.1, with a peak nonparametric linkage score of 18.41 (P<0.0007). Multipoint parametric analysis gave a logarithm of odds score of 3.17 at marker D13S132. Of the 6 related individuals with mitral valve morphologies not meeting diagnostic criteria but resembling fully developed forms, 5 carried all or part of the haplotype linked to MVP.

CONCLUSIONS

The mapping of a new MVP locus to chromosome 13 confirms the observed genetic heterogeneity and represents an important step toward gene identification. Furthermore, the genetic analysis provides clinical lessons with regard to previously nondiagnostic morphologies. In the familial context, these may represent early expression in gene carriers. Early recognition of gene carriers could potentially enhance the clinical evaluation of patients at risk of full expression, with the ultimate aim of developing interventions to reduce progression.

Murine glypican-4 gene structure and expression; Sp1 and Sp3 play a major role in glypican-4 expression in 3T3-F442A cells

In this report we describe the genomic organization of the mouse glypican-4 (Gpc4), an analysis of its promoter and its transcriptional regulation in the 3T3-F442A adipocyte cell line. The Gpc4 gene consists of nine exons separated by eight introns. A series of deletion mutants and 4391 bp of the 5'-flanking region were cloned into pGL3-BASIC upstream of the luciferase reporter gene and transfected into 3T3-F442A adipocytes. Analysis of a 4.3-kb DNA fragment at the 5'-flanking region of this gene revealed that the Gpc4 promoter is a TATA-less promoter with a large cluster of GC boxes. Competitive electrophoretic mobility shift and supershift assays identified a cluster of nine functional GC boxes binding Sp1 and Sp3 in this region. Transactivation experiments in insect cells showed that both Sp1 and Sp3 are major activators of the Gpc4 promoter. Gpc4 is expressed in adipocytes where its expression is highest in confluent 3T3-F442A adipoblasts and decreases dramatically as cells differentiate. Sp protein analyses demonstrated a major decrease in Sp3 protein in differentiated adipocytes as compared to undifferentiated adipoblasts. These experiments show that Gpc4 is developmentally regulated in 3T3-F442A adipocytes and suggest that Sp transcription factors play a significant role in the regulated expression of Gpc4.

The loss of glypican-3 induces alterations in Wnt signaling

Loss-of-function mutations of the GPC3 gene are the cause of the human Simpson-Golabi-Behmel syndrome. Based on the overgrowth phenotype of the Simpson-Golabi-Behmel syndrome patients and the key role played by the insulin-like growth factor (IGF) signaling system in regulating embryonic growth, it was speculated that GPC3 regulates IGF signaling. In order to test the validity of this hypothesis, we mated GPC3 knockout mice with insulin receptor substrate-1 (IRS-1) nullizygous mice. We found that GPC3 regulates organism growth independent of IRS-1, suggesting that GPC3 does not modulate IGF signaling. Instead, we found that GPC3 knockout mice exhibit alterations in the Wnt signaling pathway, which is also associated with the regulation of cell proliferation. In particular, the loss of GPC3 led to the inhibition of the non-canonical Wnt/JNK signaling pathway, while concomitantly causing the activation of canonical Wnt/beta-catenin signaling. These in vivo findings were confirmed in vitro upon the ectopic overexpression of GPC3 in mesothelioma cells. In these cells, the GPC3-induced increase in JNK activity was associated with an enhanced response to Wnt5a. Most interestingly, the heparan sulfate chains of GPC3 were not required for its stimulatory activity on Wnt5a signaling and for the formation of GPC3-Wnt5a complexes. We propose that at least in some cell types GPC3 serves as a selective regulator of Wnt signaling, by potentiating non-canonical Wnt signaling, while inhibiting the canonical Wnt signaling pathway.

Disruption of WT1 gene expression and exon 5 splicing following cytotoxic drug treatment: Antisense down-regulation of exon 5 alters target gene expression and inhibits cell survival

Deregulated expression of the Wilms' tumor gene (WT1) has been implicated in the maintenance of a malignant phenotype in leukemias and a wide range of solid tumors through interference with normal signaling in differentiation and apoptotic pathways. Expression of high levels of WT1 is associated with poor prognosis in leukemias and breast cancer. Using real-time (Taqman) reverse transcription-PCR and RNase protection assay, we have shown up-regulation of WT1 expression following cytotoxic treatment of cells exhibiting drug resistance, a phenomenon not seen in sensitive cells. WT1 is subject to alternative splicing involving exon 5 and three amino acids (KTS) at the end of exon 9, producing four major isoforms. Exon 5 splicing was disrupted in all cell lines studied following a cytotoxic insult probably due to increased exon 5 skipping. Disruption of exon 5 splicing may be a proapoptotic signal because specific targeting of WT1 exon 5–containing transcripts using a nuclease-resistant antisense oligonucleotide (ASO) killed HL60 leukemia cells, which were resistant to an ASO targeting all four alternatively spliced transcripts simultaneously. K562 cells were sensitive to both target-specific ASOs. Gene expression profiling following treatment with WT1 exon 5–targeted antisense showed up-regulation of the known WT1 target gene, thrombospondin 1, in HL60 cells, which correlated with cell death. In addition, novel potential WT1 target genes were identified in each cell line. These studies highlight a new layer of complexity in the regulation and function of the WT1 gene product and suggest that antisense directed to WT1 exon 5 might have therapeutic potential.

Glycosyltransferase encoding gene EXTL3 is differentially expressed in the developing and adult mouse cerebral cortex

Exostosin tumor-like 3 (EXTL3) is a glycosyltransferase involved in heparan sulfate (HS) biosynthesis. HS proteoglycans are critically involved in different steps during brain development. The present in situ hybridization in mice revealed wide EXTL3 expression at different grades in the central and peripheral nervous system components including the neural retina and neural crest-derived structures at embryonic days (E) 11.5, E12.5, E14.5, and E16.5. In the neopallial cortex, an intense EXTL3 expression was observed in the neuroepithelial cells lining the ventricular zone at E11.5 and E12.5. The signal decreased at E14.5 and was further downregulated at E16.5 in the ventricular zone. The pioneer neurons of the preplate at E12.5 differentially expressed the gene. Heavily stained among weakly or negatively stained neurons were observed. At E14.5, the cortical plate cells were moderately and homogeneously stained. In contrast, at E16.5, an upregulated and differential expression pattern was detected. The labeling pattern at E16.5 subdivided the cortical plate cells into a large number of heavily, a moderate number of less intensely, and some negatively stained cell populations. Interestingly, the distinct expression pattern displayed by the three main cell types of the adult cerebral cortex was similar to that of the late corticogenesis stage (E16.5). In the adult, the strongest expression was observed in the pyramidal neurons. The granule-type neurons showed less intense staining while the glia cells were devoid of signals. Our data revealed that EXTL3 expression is developmentally regulated in the mouse nervous system and suggested that it differentially contributes to brain development and corticogenesis.

Effects of Syndecan-1 and Glypican on Muscle Cell Proliferation and Differentiation: Implications for Possible Functions During Myogenesis

The heparan sulfate proteoglycans, syndecan-1 and glypican, are low-affinity receptors for fibroblast growth factor 2 (FGF2). Because FGF2 is a potent stimulator of skeletal muscle cell proliferation and a strong inhibitor of differentiation, it is likely that changes in syndecan-1 and glypican expression will affect myogenesis as both, in part, regulate FGF-dependent signaling. In the current study, expression vector constructs containing either syndecan-1 or glypican were transfected into turkey myogenic satellite cells resulting in the overexpression of these genes. The amount of expression of each of these genes was measured by semiquantitative reverse transcriptase polymerase chain reaction. The satellite cell cultures overexpressing syndecan-1 were unable to fuse to form multinucleated myotubes after differentiation was induced. The syndecan-1-transfected cells maintained a rounded morphology typical of cells during proliferation. In contrast, the satellite cells transfected with glypican formed larger myotubes. These results suggest that both syndecan-1 and glypican play pivotal, but different, roles in both muscle cell proliferation and differentiation.

GPC5 is a possible target for the 13q31-q32 amplification detected in lymphoma cell lines

Comparative genomic hybridization (CGH) analyses have detected gains of copy number on 13q, especially at 13q31-q32, in cell lines and primary cases of various types of lymphoma. Since amplification of chromosomal DNA is one of the mechanisms that can activate tumor-associated genes, and because 13q amplification had been reported in various other types of tumors as well, we attempted to define by fluorescence in situ hybridization (FISH) a common region at 13q31-q32 in which to explore genes that might be targets for the amplification events. Although the commonly amplified region we defined was relatively large (approximately 4 Mb), only one true gene, GPC5, was found there. GPC5 was over-expressed in lymphoma cell lines that had shown amplification, in comparison with those that had not. Our findings suggest that GPC5 is a likely target for amplification, and that over-expression of this gene may contribute to development and/or progression of lymphomas and other tumors.

The role of glypicans in mammalian development

Glypicans are a family of heparan sulfate proteoglycans that are bound to the cell surface by a glycosyl-phosphatidylinositol anchor. Six members of this family have been identified in mammals. In general, glypicans are highly expressed during development, and their expression pattern suggests that they are involved in morphogenesis. One member of this family, glypican-3, is mutated in the Simpson-Golabi-Behmel syndrome. This syndrome is characterized by overgrowth and various developmental abnormalities that indicate that glypican-3 inhibits proliferation and cell survival in the embryo. It has consequently been proposed that glypicans can regulate the activity of several growth factors that play a critical role in morphogenesis.