SRPX2 is a novel chondroitin sulfate proteoglycan that is overexpressed in gastrointestinal cancer

SRPX2 promotes cancer cell proliferation and migration of papillary thyroid cancer

Thyroid cancer is the endocrine tumor with the highest incidence at present. It originates from the thyroid follicular epithelium or follicular paraepithelial cells. There is an increasing incidence of thyroid cancer all over the world. We found that SRPX2 expression level was higher in papillary thyroid tumors than in normal thyroid tissues, and SRPX2 expression was closely related to tumor grade and clinical prognosis. Previous reports showed that SRPX2 could function by activating PI3K/AKT signaling pathway. In addition, in vitro experiments showed that SRPX2 promoted the proliferation and migration of papillary thyroid cancer (PTC). In conclusion, SRPX2 could promote the malignant development of PTC. This may be a potential treatment target for PTC.

Lymphangiogenesis in gastric cancer: function and mechanism

Increased lymphangiogenesis and lymph node (LN) metastasis are thought to be important steps in cancer metastasis, and are associated with patient's poor prognosis. There is increasing evidence that the lymphatic system may play a crucial role in regulating tumor immune response and limiting tumor metastasis, since tumor lymphangiogenesis is more prominent in tumor metastasis and diffusion. Lymphangiogenesis takes place in embryonic development, wound healing, and a variety of pathological conditions, including tumors. Tumor cells and tumor microenvironment cells generate growth factors (such as lymphangiogenesis factor VEGF-C/D), which can promote lymphangiogenesis, thereby inducing the metastasis and diffusion of tumor cells. Nevertheless, the current research on lymphangiogenesis in gastric cancer is relatively scattered and lacks a comprehensive understanding. Therefore, in this review, we aim to provide a detailed perspective on molecules and signal transduction pathways that regulate gastric cancer lymphogenesis, which may provide new insights for the diagnosis and treatment of cancer.

An In Silico Analysis Reveals Sustained Upregulation of Neuroprotective Genes in the Post-Stroke Human Brain

Ischemic stroke is a cerebrovascular disease caused by an interruption of blood flow to the brain, thus determining a lack of oxygen and nutrient supply. The ischemic event leads to the activation of several molecular signaling pathways involved in inflammation and the production of reactive oxygen species, causing irreversible neuronal damage. Several studies have focused on the acute phase of ischemic stroke. It is not clear if this traumatic event can influence some of the molecular processes in the affected area even years after the clinical event. In our study, we performed an in silico analysis using freely available raw data with the purpose of evaluating the transcriptomic state of post-mortem brain tissue. The samples were taken from non-fatal ischemic stroke patients, meaning that they suffered an ischemic stroke and lived for a period of about 2 years after the event. These samples were compared with healthy controls. The aim was to evaluate possible recovery processes useful to mitigating neuronal damage and the detrimental consequences of stroke. Our results highlighted differentially expressed genes codifying for proteins along with long non-coding genes with anti-inflammatory and anti-oxidant functions. This suggests that even after an amount of time from the ischemic insult, different neuroprotective mechanisms are activated to ameliorate brain conditions and repair post-stroke neuronal injury.

SRPX2 Promotes Tumor Proliferation and Migration via the FAK Pathway in Papillary Thyroid Carcinoma

Thyroid cancer is the most common form of endocrine cancer around the world, and among which papillary thyroid carcinoma (PTC) is the most ubiquitous pathological sub-kind. Sushi repeat-containing protein X-linked 2 (SRPX2) was reported to be an independent prognostic factor and significantly overexpressed in advanced PTC patients. However, the biological functions of SRPX2 remain ambiguous in PTC. Here, we explored SRPX2 expression profiles and functions in PTC, finding that SRPX2 expression was remarkably upregulated in PTC tissues and cell lines. Further colony formation, CCK-8, as well as transwell assay, suggested that SRPX2 silencing remarkably dampened PTC growth and migration. Mouse xenograft models were established to find that SRPX2 silence remarkably suppressed PTC proliferation and migration in vivo. Following mechanism studies revealed that SRPX2 realized its functions in the PTC process partially through activating the Focal adhesion kinase (FAK) phosphorylation. In conclusion, this study investigated the functions and mechanisms of the SRPX2/FAK pathway in PTC progression. SRPX2 could act as a prospective biologic signature and therapeutic target molecule for PTC.

Sushi-Repeat-Containing Protein X-Linked 2: A Potential Therapeutic Target for Inflammation and Cancer Therapy

Accumulating evidence has showed that sushi-repeat-containing protein X-linked 2 (SRPX2) is an abnormal expression in a variety of cancers and involved in cancer carcinogenesis, chemosensitivity, and prognosis, which mainly promote cancer cell metastasis, invasion, and migration by regulating the uPAR/integrins/FAK signaling pathway, epithelial-mesenchymal transition (EMT), angiogenesis, and glycosylation. Inflammation has been regarded as a key role in regulating cancer initiation, progression, EMT, and therapeutics. Furthermore, SRPX2 exhibited excellent antifibrosis effect via the TGFβR1/SMAD3/SRPX2/AP1/SMAD7 signaling pathway. Therefore, this review provides compelling evidence that SRPX2 might be a therapeutic target for inflammation and cancer-related inflammation for future cancer therapeutics.

Site-specific glycosylation of proteoglycans: a revisited frontier in proteoglycan research

Proteoglycans (PGs), a class of carbohydrate-modified proteins, are present in essentially all metazoan organisms investigated to date. PGs are composed of glycosaminoglycan (GAG) chains attached to various core proteins and are important for embryogenesis and normal homeostasis. PGs exert many of their functions via their GAG chains and understanding the details of GAG-ligand interactions has been an essential part of PG research. Although PGs are also involved in many diseases, the number of GAG-related drugs used in the clinic is yet very limited, indicating a lack of detailed structure-function understanding. Structural analysis of PGs has traditionally been obtained by first separating the GAG chains from the core proteins, after which the two components are analyzed separately. While this strategy greatly facilitates the analysis, it precludes site-specific information and introduces either a "GAG" or a "core protein" perspective on the data interpretation. Mass-spectrometric (MS) glycoproteomic approaches have recently been introduced, providing site-specific information on PGs. Such methods have revealed a previously unknown structural complexity of the GAG linkage regions and resulted in identification of several novel CSPGs and HSPGs in humans and in model organisms, thereby expanding our view on PG complexity. In light of these findings, we discuss here if the use of such MS-based techniques, in combination with various functional assays, can also be used to expand our functional understanding of PGs. We have also summarized the site-specific information of all human PGs known to date, providing a theoretical framework for future studies on site-specific functional analysis of PGs in human pathophysiology.

Proteoglycans and Glycosaminoglycans in Central Nervous System Injury

The brain and spinal cord constitute the central nervous system (CNS), which when injured, can be exceedingly devastating. The mechanistic roles of proteoglycans (PGs) and their glycosaminoglycan (GAG) side chains in such injuries have been extensively studied. CNS injury immediately alters endothelial and extracellular matrix (ECM) PGs and GAGs. Subsequently, these alterations contribute to acute injury, post-injury fibrosis, and post-injury repair. These effects are central to the pathophysiology of CNS injury. This review focuses on the importance of PGs and GAGs in multiple forms of injury including traumatic brain injury, spinal cord injury, and stroke. We highlight the causes and consequences of degradation of the PG and GAG-enriched endothelial glycocalyx in early injury and discuss the pleiotropic roles of PGs in neuroinflammation. We subsequently evaluate the dualistic effects of PGs on recovery: both PG/GAG-mediated inhibition and facilitation of repair. We then report promising therapeutic strategies that may prove effective for repair of CNS injury including PG receptor inhibition, delivery of endogenous, pro-repair PGs and GAGs, and direct degradation of pathologic GAGs. Last, we discuss importance of two PG- and GAG-containing ECM structures (synapses and perineuronal nets) in CNS injury and recovery.

Searching for New Molecular Targets for Oral Squamous Cell Carcinoma with a View to Clinical Implementation of Precision Medicine

Head and neck cancer, including oral squamous cell carcinoma (OSCC), is the eighth most common malignancy globally and is characterized by local invasiveness and high nodal metastatic potential. The OSCC incidence is also increasing, and the number of deaths is also rising steadily in Japan. The development of molecular markers to eradicate OSCC is an urgent issue for humankind. The increase in OSCC despite the declining smoking rate may be due to several viral infections through various sexual activities and the involvement of previously unfocused carcinogens, and genetic alterations in individual patients are considered to be more complicated. Given this situation, it is difficult to combat OSCC with conventional radiotherapy and chemotherapy using cell-killing anticancer drugs alone, and the development of precision medicine, which aims to provide tailor-made medicine based on the genetic background of each patient, is gaining attention. In this review article, the current status of the comprehensive search for driver genes and biomarkers in OSCC will be briefly described, and some of the candidates for novel markers of OSCC that were found will be outlined.

The Landscape of the Tumor Microenvironment in Skin Cutaneous Melanoma Reveals a Prognostic and Immunotherapeutically Relevant Gene Signature

The tumorigenesis of skin cutaneous melanoma (SKCM) remains unclear. The tumor microenvironment (TME) is well known to play a vital role in the onset and progression of SKCM. However, the dynamic mechanisms of immune regulation are insufficient. We conducted a comprehensive analysis of immune cell infiltration in the TME. Based on the differentially expressed genes (DEGs) in clusters grouped by immune infiltration status, a set of hub genes related to the clinical prognosis of SKCM and tumor immune infiltration was explored. Methods: We analyzed immune cell infiltration in two independent cohorts and assessed the relationship between the internal pattern of immune cell infiltration and SKCM characteristics, including clinicopathological features, potential biological pathways, and gene mutations. Genes related to the infiltration pattern of TME immune cells were determined. Furthermore, the unsupervised clustering method (k-means) was used to divide samples into three different categories according to TME, which were defined as TME cluster-A, -B, and -C. DEGs among three groups of samples were analyzed as signature genes. We further distinguished common DEGs between three groups of samples according to whether differences were significant and divided DEGs into the Signature gene-A group with significant differences and the Signature gene-B group with insignificant differences. The Signature gene-A gene set mainly had exon skipping in SKCM, while the Signature gene-B gene set had no obvious alternative splicing form. Subsequently, we analyzed genetic variations of the two signatures and constructed a competing endogenous RNA (ceRNA) regulatory network. LASSO Cox regression was used to determine the immune infiltration signature and risk score of SKCM. Finally, we obtained 13 hub genes and calculated the risk score based on the coefficient of each gene to explore the impact of the high- and low-risk scores on biologically related functions and prognosis of SKCM patients further. The correlation between the risk score and clinicopathological characteristics of SKCM patients indicated that a low-risk score was associated with TME cluster-A classification (p < 0.001) and metastatic SKCM (p < 0.001). Thirteen hub genes also showed different prognostic effects in pan-cancer. The results of univariate and multivariate Cox analyses revealed that risk score could be used as an independent risk factor for predicting the prognosis of SKCM patients. The nomogram that integrated clinicopathological characteristics and immune characteristics to predict survival probability was based on multivariate Cox regression. Finally, 13 hub genes that showed different prognostic effects in pan-cancers were obtained. According to immunohistochemistry staining results, Ube2L6, SRPX2, and IFIT2 were expressed at higher levels, while CLEC4E, END3, and KIR2DL4 were expressed at lower levels in 25 melanoma specimens. Conclusion: We performed a comprehensive assessment of the immune-associated TME. To elucidate the potential development of immune-genomic features in SKCM, we constructed an unprecedented set of immune characteristic genes (EDN3, CLEC4E, SRPX2, KIR2DL4, UBE2L6, and IFIT2) related to the immune landscape of TME. These genes are related to different prognoses and drug responses of SKCM. The immune gene signature constructed can be used as a robust prognostic biomarker of SKCM and a predictor of an immunotherapy effect.

The Extracellular Small Leucine-Rich Proteoglycan Biglycan Is a Key Player in Gastric Cancer Aggressiveness

Simple Summary

Approximately 80% of gastric cancer patients are diagnosed at advanced stages with an average five-year survival rate of less than 30%. Alterations of the extracellular matrix proteins have been largely demonstrated in all steps of the disease. Thus, studies for the identification of novel prognostic biomarkers and efficient therapeutic strategies are urgently needed. In this study, we report the oncogenic role of biglycan, an extracellular proteoglycan, in gastric carcinogenesis. Biglycan was able to modulate gastric cancer aggressive features as cell survival, migration, and angiogenesis. Additionally, high levels of biglycan expression correlates with tumorigenic gene signatures and they are associated with poor patient prognosis in advanced stages of the disease. These results point biglycan as a key player in gastric cancer aggressiveness and further studies should be done to investigate the therapeutic potential of biglycan to tackle gastric cancer progression.

Abstract

Biglycan (BGN gene), an extracellular proteoglycan, has been described to be associated with cancer aggressiveness. The purpose of this study was to clarify the clinical value of biglycan as a biomarker in multiple independent GC cohorts and determine the in vitro and in vivo role of biglycan in GC malignant features. We found that BGN is commonly over-expressed in all analyzed cohorts, being associated with disease relapse and poor prognosis in patients with advanced stages of disease. In vitro and in vivo experiments demonstrated that biglycan knock-out GC cells display major phenotypic changes with a lower cell survival, migration, and angiogenic potential when compared with biglycan expressing cells. Biglycan KO GC cells present increased levels of PARP1 and caspase-3 cleavage and a decreased expression of mesenchymal markers. Importantly, biglycan deficient GC cells that were supplemented with exogenous biglycan were able to restore biological features, such as survival, clonogenic and migratory capacities. Our in vitro and in vivo findings were validated in human GC samples, where BGN expression was associated with several oncogenic gene signatures that were associated with apoptosis, cell migration, invasion, and angiogenesis. This study provided new insights on biglycan role in GC that should be taken in consideration as a key cellular regulator with major impact in tumor progression and patients’ clinical outcome.

Calcineurin A gamma and NFATc3/SRPX2 axis contribute to human embryonic stem cell differentiation

Our understanding of signaling pathways regulating the cell fate of human embryonic stem cells (hESCs) is limited. Calcineurin-NFAT signaling is associated with a wide range of biological processes and diseases. However, its role in controlling hESC fate remains unclear. Here, we report that calcineurin A gamma and the NFATc3/SRPX2 axis control the expression of lineage and epithelial-mesenchymal transition (EMT) markers in hESCs. Knockdown of PPP3CC, the gene encoding calcineurin A gamma, or NFATC3, downregulates certain markers both at the self-renewal state and during differentiation of hESCs. Furthermore, NFATc3 interacts with c-JUN and regulates the expression of SRPX2, the gene encoding a secreted glycoprotein known as a ligand of uPAR. We show that SRPX2 is a downstream target of NFATc3. Both SRPX2 and uPAR participate in controlling expression of lineage and EMT markers. Importantly, SRPX2 knockdown diminishes the upregulation of multiple lineage and EMT markers induced by co-overexpression of NFATc3 and c-JUN in hESCs. Together, this study uncovers a previously unknown role of calcineurin A gamma and the NFATc3/SRPX2 axis in modulating the fate determination of hESCs.

SRPX2 boosts pancreatic cancer chemoresistance by activating PI3K/AKT axis

Background and aim

This investigation was aimed at disclosing whether SRPX2 affected pancreatic cancer (PC) chemoresistance by regulating PI3K/Akt/mTOR signaling.

Methods

Totally 243 PC patients were recruited, and they were incorporated into partial remission (PR) group, stable disease (SD) group and progressive disease (PD) group in accordance with their chemotherapeutic response. PC cell lines (i.e. AsPC1, Capan2, VFPAC-1, HPAC, PANC-1, BxPC-3 and SW1990) and human pancreatic ductal epithelial cell lines (hTERT-HPNE) were also collected.

Results

PC patients of SD + PD group were associated with higher post-chemotherapeutic SRPX2 level than PR group, and their post-chemotherapeutic SRPX2 level was above the pretherapeutic SRPX2 level (P < 0.05). PR population showed lower SRPX2 level after chemotherapy than before chemotherapy (P < 0.05). Besides high serum SRPX2 level and SRPX2 level change before and after chemotherapy were independent predictors of poor PC prognosis. Additionally, si-SRPX2 enhanced chemosensitivity of PC cell lines, and expressions of p-PI3K, p-AKT and p-mTOR were suppressed by si-SRPX2 (P < 0.05). IGF-1 treatment could changeover the impact of si-SRPX2 on proliferation, migration, invasion and chemoresistance of PC cells (P < 0.05).

Conclusion

The SRPX2-PI3K/AKT/mTOR axis could play a role in modifying progression and chemoresistance of PC cells, which might help to improve PC prognosis.

Sushi Repeat Containing Protein X-linked 2 Is a Downstream Signal of LEM Domain Containing 1 and Acts as a Tumor-Promoting Factor in Oral Squamous Cell Carcinoma

Because oral squamous cell carcinomas (OSCCs) have a high potential for locoregional invasion and nodal metastasis, early detection and treatment are essential. A LAP2, emerin, MAN1 (LEM) domain containing 1 (LEMD1) is associated with local progression, clinical stage, nodal metastasis, poor prognosis, angiogenesis, and lymphangiogenesis in OSCC. Although LEMD is a cancer-testis antigen, the cancer-related signals related to LEMD1 remain unknown. In this study, we used a microarray analysis of OSCC cells to identify sushi repeat containing protein X-linked 2 (SRPX2) as a LEMD1-related downstream signal. LEMD1 expression was correlated with lymph node metastasis of OSCC according to the immunohistochemistry analysis. Furthermore, patients expressing SRPX2 had a significantly worse prognosis than those without SRPX2 expression. The concentration of SRPX2 in OSCC was positively correlated with the concentrations of LEMD1, urokinase plasminogen activator receptor (uPAR), and hepatocyte growth factor (HGF). In OSCC cells, SRPX2 secretion levels were elevated by interactions with uPAR and HGF. We also found that SRPX2 promotes endothelial cell proliferation and adhesion between endothelial cells and OSCC cells. These results suggest that SRPX2 might be a useful tumor marker for OSCC.

Transcriptome signature of cellular senescence

Cellular senescence, an integral component of aging and cancer, arises in response to diverse triggers, including telomere attrition, macromolecular damage and signaling from activated oncogenes. At present, senescent cells are identified by the combined presence of multiple traits, such as senescence-associated protein expression and secretion, DNA damage and β-galactosidase activity; unfortunately, these traits are neither exclusively nor universally present in senescent cells. To identify robust shared markers of senescence, we have performed RNA-sequencing analysis across eight diverse models of senescence triggered in human diploid fibroblasts (WI-38, IMR-90) and endothelial cells (HUVEC, HAEC) by replicative exhaustion, exposure to ionizing radiation or doxorubicin, and expression of the oncogene HRASG12V. The intersection of the altered transcriptomes revealed 50 RNAs consistently elevated and 18 RNAs consistently reduced across all senescence models, including many protein-coding mRNAs and some non-coding RNAs. We propose that these shared transcriptome profiles will enable the identification of senescent cells in vivo, the investigation of their roles in aging and malignancy and the development of strategies to target senescent cells therapeutically.

O-glycans truncation modulates gastric cancer cell signaling and transcription leading to a more aggressive phenotype

BACKGROUND

Changes in glycosylation are known to play critical roles during gastric carcinogenesis. Expression of truncated O-glycans, such as the Sialyl-Tn (STn) antigen, is a common feature shared by many cancers and is associated with cancer aggressiveness and poor-prognosis.

METHODS

Glycoengineered cell lines were used to evaluate the impact of truncated O-glycans in cancer cell biology using in vitro functional assays, transcriptomic analysis and in vivo models. Tumor patients 'samples and datasets were used for clinical translational significance evaluation.

FINDINGS

In the present study, we demonstrated that gastric cancer cells expressing truncated O-glycans display major phenotypic alterations associated with higher cell motility and cell invasion. Noteworthy, the glycoengineered cancer cells overexpressing STn resulted in tumor xenografts with less cohesive features which had a critical impact on mice survival. Furthermore, truncation of O-glycans induced activation of EGFR and ErbB2 receptors and a transcriptomic signature switch of gastric cancer cells. The disclosed top activated genes were further validated in gastric tumors, revealing that SRPX2 and RUNX1 are concomitantly overexpressed in gastric carcinomas and its expression is associated with patients' poor-survival, highlighting their prognosis potential in clinical practice.

INTERPRETATION

This study discloses novel molecular links between O-glycans truncation frequently observed in cancer and key cellular regulators with major impact in tumor progression and patients' clinical outcome.

Knockdown of SRPX2 inhibits the proliferation, migration, and invasion of prostate cancer cells through the PI3K/Akt/mTOR signaling pathway

Sushi repeat-containing protein X-linked 2 (SRPX2), a novel chondroitin sulfate proteoglycan, is reported to play a critical role in tumorigenesis. However, the expression and functional role of SRPX2 in prostate cancer have not been defined. Thus, the aim of this study was to investigate the expression and functional role of SRPX2 in human prostate cancer. Our results showed that the expression of SRPX2 was obviously increased in human prostate cancer tissues and cell lines. In addition, knockdown of SRPX2 inhibited the proliferation, migration, and invasion of prostate cancer cells, as well as prevented the epithelial-mesenchymal transition process in prostate cancer cells. Mechanically, knockdown of SRPX2 efficiently inhibited the activation of PI3K/Akt/mTOR pathway in prostate cancer cells. Taken together, these data demonstrated that knockdown of SRPX2 inhibits the proliferation and metastasis in human prostate cancer cells, partly through the PI3K/Akt/mTOR signaling pathway. Thus, SRPX2 may be a novel therapeutic target for the treatment of prostate cancer.

Exploring the association between SRPX2 variants and neurodevelopment: How causal is it?

The SRPX2 gene (Sushi-repeat-containing protein, X-linked, 2, OMIM*300642), located on Xq22.1, encodes a secreted protein that is highly expressed in neurons of cerebral cortex. SRPX2 was first implicated in neurodevelopment, learning and rolandic seizure when two patients with potentially pathogenic variants, c.980A>G (p.Asn327Ser) and c.215A>C (p.Tyr72Ser), in SRPX2 gene were identified. Subsequent experimental studies demonstrated that SRPX2 is needed for vocalization and synapse formation in mice, and that both silencing SRPX2 and injecting (p.Asn327Ser) in mouse models results in alteration in neuronal migration in cerebral cortex and epilepsy. A number of studies demonstrated that SRPX2 interacts with FOXP2 (Foxhead box protein P2), a gene responsible for speech and language disorder, and that FoxP2 controls timing and level of expression of SRPX2. Despite the supportive evidence for the role of SRPX2 in speech and language development and disorders, there are questions over its definitive association with neurodevelopmental disorders and epilepsy. In this paper, the role of SRPX2 as one in a network of many genes involved in speech and language is discussed. The goal of this paper is to examine the role of SRPX2 variants through describing two patients with potentially pathogenic variants in SRPX2, c.751G>C (p.Ala251Pro) and c.762G>T (p.Lys254Asn) presenting with language and motor delay, intellectual disability as well as congenital anomalies. We explore the contribution of SRPX2 variants to clinical phenotype in our patients and conclude that these variants at least partially explain the phenotype. Further studies are necessary to establish and confirm the association between SRPX2 and neurodevelopment particularly speech and language development.

Sociability and synapse subtype-specific defects in mice lacking SRPX2, a language-associated gene

The FoxP2 transcription factor and its target genes have been implicated in developmental brain diseases with a prominent language component, such as developmental verbal dyspraxia and specific language impairment. How FoxP2 affects neural circuitry development remains poorly understood. The sushi domain protein SRPX2 is a target of FoxP2, and mutations in SRPX2 are associated with language defects in humans. We have previously shown that SRPX2 is a synaptogenic protein that increases excitatory synapse density. Here we provide the first characterization of mice lacking the SRPX2 gene, and show that these mice exhibit defects in both neural circuitry and communication and social behaviors. Specifically, we show that mice lacking SRPX2 show a specific reduction in excitatory VGlut2 synapses in the cerebral cortex, while VGlut1 and inhibitory synapses were largely unaffected. SRPX2 KO mice also exhibit an abnormal ultrasonic vocalization ontogenetic profile in neonatal pups, and reduced preference for social novelty. These data demonstrate a functional role for SRPX2 during brain development, and further implicate FoxP2 and its targets in regulating the development of vocalization and social circuits.

High SRPX2 protein expression predicts unfavorable clinical outcome in patients with prostate cancer

Background

Sushi repeat-containing protein X-linked 2 (SRPX2) is overexpressed in a variety of different tumor tissues and correlated with poor prognosis in patients. Little research focuses on the role of SRPX2 expression in prostate cancer (PCa), and the clinicopathological significance of the protein expression in this tumor is relatively unknown. However, our previous transcriptome data from those cancer stem-like cells indicated the role of SRPX2 in PCa.

Materials and methods

In this study, RT-PCR and Western blotting were firstly used to examine the SRPX2 expression in three PCa cell lines including LNCaP, DU145, and PC3, and then SRPX2 protein expression was immunohistochemically investigated and statistically analyzed in a series of 106 paraffin-embedded PCa tissue specimens.

Results

Significantly lower levels of SRPX2 expression were verified in the LNCaP cells, compared with the expression in the aggressive DU145 and PC3 cells, in both mRNA and protein levels. Immunohistochemically, there were variable SRPX2 protein expressions in the clinical samples. Moreover, high levels of SRPX2 expression in the PCa tissues were significantly associated with Gleason score (P=0.008), lymph node metastasis (P=0.009), and distant metastasis (P=0.021). Furthermore, higher levels of SRPX2 expression in the PCa tissues were significantly associated with shorter overall survival (OS) (P<0.001).

Conclusion

Our results demonstrate that SRPX2 is highly expressed in aggressive PCa cells in vitro, and its protein expression in PCa is significantly associated with malignant clinical features and shorter OS, strongly indicating its prognostic value in prostate cancers.

Biodiversity of CS–proteoglycan sulphation motifs: chemical messenger recognition modules with roles in information transfer, control of cellular behaviour and tissue morphogenesis

Chondroitin sulphate (CS) glycosaminoglycan chains on cell and extracellular matrix proteoglycans (PGs) can no longer be regarded as merely hydrodynamic space fillers. Overwhelming evidence over recent years indicates that sulphation motif sequences within the CS chain structure are a source of significant biological information to cells and their surrounding environment. CS sulphation motifs have been shown to interact with a wide variety of bioactive molecules, e.g. cytokines, growth factors, chemokines, morphogenetic proteins, enzymes and enzyme inhibitors, as well as structural components within the extracellular milieu. They are therefore capable of modulating a panoply of signalling pathways, thus controlling diverse cellular behaviours including proliferation, differentiation, migration and matrix synthesis. Consequently, through these motifs, CS PGs play significant roles in the maintenance of tissue homeostasis, morphogenesis, development, growth and disease. Here, we review (i) the biodiversity of CS PGs and their sulphation motif sequences and (ii) the current understanding of the signalling roles they play in regulating cellular behaviour during tissue development, growth, disease and repair.

Proteome profiling in IL-1β and VEGF-activated human umbilical vein endothelial cells delineates the interlink between inflammation and angiogenesis

Endothelial cells represent major effectors in inflammation and angiogenesis, processes that drive a multitude of pathological states such as atherosclerosis and cancer. Both inflammation and angiogenesis are interconnected with each other in the sense that many pro-inflammatory proteins possess proangiogenic properties and vice versa. To elucidate this interplay further, we present a comparative proteome study of inflammatory and angiogenic activated endothelial cells. HUVEC were stimulated with interleukin 1-β and VEGF, respectively. Cultured primary cells were fractionated into secreted, cytoplasmic and nuclear protein fractions and processed for subsequent LC-MS/MS analysis. Obtained protein profiles were filtered for fraction-specific proteins to address potential cross fractional contamination, subjected to comparative computational biology analysis (GO-Term enrichment analysis, weighted gene co-expression analysis) and compared to published mRNA profiles of IL-1β respectively VEGF stimulated HUVEC. GO Term enrichment analysis and comparative pathway analysis revealed features such as NOD and NfkB signaling for inflammatory activated HUVEC and VEGF and ErB signaling for VEGF-activated HUVEC with potential crosstalk via map kinases MAP2K2. Weighted protein co-expression network analysis revealed several potential hub genes so far not associated with driver function in inflammation or angiogenesis such as HSPG2, ANXA3, and GPI. "Classical" inflammation or angiogenesis markers such as IL6, CXCL8 or CST1 were found in a less central position within the co-expression networks. In conclusion, this study reports a framework for the computational biology based analysis of proteomics data applied to cytoplasmic, nucleic and extracellular fractions of quiescent, inflammatory and angiogenic activated HUVEC. Novel potential hub genes relevant for these processes were successfully identified.

SRPX2 Enhances the Epithelial-Mesenchymal Transition and Temozolomide Resistance in Glioblastoma Cells

Glioblastoma (GBM) is the most common and most aggressive central nervous system tumor in adults. Due to GBM cell invasiveness and resistance to chemotherapy, current medical interventions are not satisfactory, and the prognosis for GBM is poor. It is necessary to investigate the underlying mechanism of GBM metastasis and drug resistance so that more effective treatments can be developed for GBM patients. sushi repeat-containing protein, X-linked 2 (SRPX2) is a prognostic biomarker in many different cancer cell lines and is associated with poor prognosis in cancer patients. SRPX2 overexpression promotes interactions between tumor and endothelial cells, leading to tumor progression and metastasis. We hypothesize that SRPX2 also contributes to GBM chemotherapy resistance and metastasis. Our results revealed that GBM tumor samples from 42 patients expressed higher levels of SRPX2 than the control normal brain tissue samples. High-SRPX2 expression levels are correlated with poor prognosis in those patients, as well as resistance to temozolomide in cultured GBM cells. Up-regulating SRPX2 expression in cultured GBM cell lines facilitated invasiveness and migration of GBM cells, while down-regulating SRPX2 through RNA interference was inhibitory. These results suggest that SRPX2 plays an important role in GBM metastasis. Epithelial to mesenchymal transition (EMT) is one of the processes that facilitate GBM metastasis and resistance to chemotherapy. EMT marker expression was decreased in SRPX2 down-regulated GBM cells, and MAPK signaling pathway marker expression was also decreased when SRPX2 is knocked down in GBM-cultured cells. Blocking the MAPK signaling pathway inhibited GBM metastasis but did not inhibit cell invasion and migration in SRPX2 down-regulated cells. Our results indicate that SRPX2 facilitates GBM metastasis by enhancing the EMT process via the MAPK signaling pathway.

A Proteoglycan-Like Molecule Offers Insights Into Ground Substance Changes During Holothurian Intestinal Regeneration

Extracellular matrix remodeling is an essential component of regenerative processes in metazoans. Among these animals, holothurians (sea cucumbers) are distinguished by their great regenerative capacities. We have previously shown that fibrous collagen as well as other fibrous components disappear from the connective tissue (CT) early during intestinal regeneration, and later return as the organ primordia form. We now report on changes of the nonfibrous component of the CT. We have used Alcian Blue staining and an antibody, Proteoglycan Like-1 (PGL-1), that recognizes a proteoglycan-like antigen to identify the presence of proteoglycans in normal and regenerating intestines. Our results show that early in regeneration, the ground substance resembles that of the mesentery, the structure from where the new intestine originates. As regeneration proceeds, Alcian Blue staining and PGL-1 labeling reorganize, so that by 4 weeks the normal intestinal CT pattern is achieved. Together with our previous findings, the data suggest that CT components that might be detrimental to regeneration disappear early on, while those that might be beneficial to regeneration, such as proteoglycans, are present throughout the regenerative process.

Global comparison of chromosome X genes of pulmonary telocytes with mesenchymal stem cells, fibroblasts, alveolar type II cells, airway epithelial cells, and lymphocytes

Background

Telocytes (TCs) are suggested as a new type of interstitial cells with specific telopodes. Our previous study evidenced that TCs differed from fibroblasts and stem cells at the aspect of gene expression profiles. The present study aims to search the characters and patterns of chromosome X genes of TC-specific or TC-dominated gene profiles and fingerprints, investigate the network of principle genes, and explore potential functional association.

Methods

We compared gene expression profiles in chromosome X of pulmonary TCs with mesenchymal stem cells (MSC), fibroblasts (Fb), alveolar type II cells (ATII), airway basal cells (ABC), proximal airway cells (PAC), CD8⁺ T cells come from bronchial lymph nodes (T-BL), or CD8⁺ T cells from lungs (T-L) by global analyses, and selected the genes which were consistently up or down regulated (>1 fold) in TCs compared to other cells as TC-specific genes. The functional and characteristic networks were identified and compared by bioinformatics tools.

Results

We selected 31 chromosome X genes as the TC-specific or dominated genes, among which 8 up-regulated (Flna, Msn, Cfp, Col4a5, Mum1l1, Rnf128, Syn1, and Srpx2) and 23 down-regulated (Abcb7, Atf1, Ddx26b, Drp2, Fam122b, Gyk, Irak1, Lamp2, Mecp2, Ndufb11, Ogt, Pdha1, Pola1, Rab9, Rbmx2, Rhox9, Thoc2, Vbp1, Dkc1, Nkrf, Piga, Tmlhe and Tsr2), as compared with other cells.

Conclusions

Our data suggested that gene expressions of chromosome X in TCs are different with those in other cells in the lung tissue. According to the selected TC-specific genes, we infer that pulmonary TCs function as modulators which may enhance cellular growth and migration, resist senescence, protect cells from external stress, regulate immune responses, participate in tissue remodeling and repair, regulate neural function, and promote vessel formation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0669-8) contains supplementary material, which is available to authorized users.

SRPX2 promotes cell migration and invasion via FAK dependent pathway in pancreatic cancer

Sushi repeat-containing protein, X-linked 2, abbreviated as SRPX2, is a candidate downstream target protein for E2A-HLF and involved in disorders of language cortex and cognition. Recent studies have demonstrated that elevated SRPX2 exhibits crucial roles in gastric cancer, however, underlying clinical significance and biological function of SRPX2 in pancreatic ductal adenocarcinoma (PDAC), remains unclear. Data from Oncomine database showed that higher SRPX2 expression is more commonly observed in PDAC compared with normal pancreatic duct, similar results were also found in 12 matched PDAC tissue samples, 7 PDAC cell lines and a tissue microarray containing 81 PDAC specimens as demonstrated by real-time quantitative PCR and immunohistochemistry, respectively. Besides, higher SRPX2 expression was closely correlated with advanced TNM stage. Silencing of endogenous SRPX2 expression reduced abilities of cell migration and invasion of PDAC cells. Further studies revealed that SRPX2 expression in PDAC tissues significantly correlated with the phosphorylation levels of FAK, indicating that FAK dependent pathway may be account for the effect of SRPX2 on cell migration and invasion in PDAC. Collectively, this study reveals that frequently elevated SRPX2 contributes to cell migration and invasion in PDAC and SRPX2-related pathways might be a potential therapeutic target for PDAC.

Increased Sushi repeat-containing protein X-linked 2 is associated with progression of colorectal cancer

Sushi repeat-containing protein X-linked 2 (SRPX2) is a novel chondroitin sulfate proteoglycan overexpressed in gastrointestinal cancer. Its role in tumor biology remains unknown. The aim of this study was to investigate the expression of SRPX2 in colorectal cancer and its potential association with cancer progression. The expression of SRPX2 and its clinicopathological significance was evaluated using immunohistochemistry in a tissue microarray including 88 colon cancer and pairing normal tissues. The impact of SRPX2 on behavior of colorectal cancer cells and possible mechanism was explored using gene transfection and silencing. Strong staining of SRPX2 was noted in 71 (80.7 %) of 88 colon cancer specimen and 30 (34.1 %) of 88 adjacent normal tissues (P < 0.001). The expression of SRPX2 was significantly correlated with histological differentiation grade (P = 0.003), infiltration depth (P = 0.003), and clinical stage (P = 0.006). The expression of SRPX2 was significantly higher in HCT116 than in HT29 and SW480 cells. Suppression of endogenous SRPX2 expression by small interfering ribonucleic acid (siRNA) in HCT116 cells resulted in significant reduction in the ability of cell proliferation, adhesion, migration, and invasion. Up-regulation of endogenous SRPX2 in SW480 cells significantly promoted the migration and invasion of SW480 cells. In addition, inhibition of SRPX2 by siRNA led to notable down-regulation of β-catenin, matrix metalloproteinase (MMP)-2, and MMP-9. These findings indicate that overexpressed SRPX2 exerts an oncogenic role in colorectal cancer. SRPX2 may promote the invasion of colorectal cancer through MMP-2 and MMP-9 modulated by Wnt/β-catenin pathway.

Who climbs the tryptophan ladder? On the structure and function of the WSXWS motif in cytokine receptors and thrombospondin repeats

For decades, a spectacular structural motif has been the focus of research in two families of animal membrane proteins: the hematopoietic cytokine type I receptors (HCR) and the thrombospondin repeat type 1 (TSR-1) domain containing proteins. Although these families include some of the best-studied and pharmaceutically most interesting human proteins, the function of the motif remains elusive. Here we show that the molecular details of the motifs are the same; that it has arisen through convergent evolution, and we argue that the same ligand binding function is maintained and suggest that the ligand can be found in the extracellular matrix (ECM). We term the motif the tryptophan ladder and suggest a function based on a comparative analysis.

Impact of overexpression of Sushi repeat-containing protein X-linked 2 gene on outcomes of gastric cancer

BACKGROUND AND OBJECTIVES

Sushi repeat-containing protein X-linked 2 (SRPX2) was first described as a downstream target gene for E2A-HLA, which causes pro-B acute leukemia. SRPX2 is considered to promote cellular migration and adhesion in cancers. Our objective was to evaluate the relative expression of the SRPX2 gene and to determine whether such expression correlates with outcomes in patients with gastric cancer.

METHODS

Surgical specimens of cancer tissue and adjacent normal mucosa obtained from 227 patients with previously untreated gastric cancer were examined. SRPX2 mRNA expression levels of cancer tissue and adjacent normal mucosa were measured by quantitative real-time polymerase chain reaction. We evaluated the clinicopathological significance of the relative expression of SRPX2 in patients with gastric cancer.

RESULTS

SRPX2 expression was higher in cancer tissue than in adjacent normal mucosa (P < 0.001). On analysis of the relations between gene expression and clinicopathological factors, SRPX2 expression correlated with tumor size and distant metastasis. Overall survival was significantly lower in patients whose tumors had high SRPX2 expression than in those who had low SRPX2 expression (P = 0.003). Multivariate analysis showed that high SRPX2 expression was an independent predictor of survival (HR = 2.028, 95% CI = 1.265-3.251).

CONCLUSIONS

SRPX2 expression was significantly higher in gastric cancer tissue than in adjacent normal mucosa, and overexpression of the SRPX2 gene is considered a useful independent predictor of outcomes in patients with gastric cancer.

Recent Advances in the Genetics of Vocal Learning

Language is a complex communicative behavior unique to humans, and its genetic basis is poorly understood. Genes associated with human speech and language disorders provide some insights, originating with the FOXP2 transcription factor, a mutation in which is the source of an inherited form of developmental verbal dyspraxia. Subsequently, targets of FOXP2 regulation have been associated with speech and language disorders, along with other genes. Here, we review these recent findings that implicate genetic factors in human speech. Due to the exclusivity of language to humans, no single animal model is sufficient to study the complete behavioral effects of these genes. Fortunately, some animals possess subcomponents of language. One such subcomponent is vocal learning, which though rare in the animal kingdom, is shared with songbirds. We therefore discuss how songbird studies have contributed to the current understanding of genetic factors that impact human speech, and support the continued use of this animal model for such studies in the future.

Tubacin prevents neuronal migration defects and epileptic activity caused by rat Srpx2 silencing in utero

Altered development of the human cerebral cortex can cause severe malformations with often intractable focal epileptic seizures and may participate in common pathologies, notably epilepsy. This raises important conceptual and therapeutic issues. Two missense mutations in the sushi repeat-containing protein SRPX2 had been previously identified in epileptic disorders with or without structural developmental alteration of the speech cortex. In the present study, we aimed to decipher the precise developmental role of SRPX2, to have a better knowledge on the consequences of its mutations, and to start addressing therapeutic issues through the design of an appropriate animal model. Using an in utero Srpx2 silencing approach, we show that SRPX2 influences neuronal migration in the developing rat cerebral cortex. Wild-type, but not the mutant human SRPX2 proteins, rescued the neuronal migration phenotype caused by Srpx2 silencing in utero, and increased alpha-tubulin acetylation. Following in utero Srpx2 silencing, spontaneous epileptiform activity was recorded post-natally. The neuronal migration defects and the post-natal epileptic consequences were prevented early in embryos by maternal administration of tubulin deacetylase inhibitor tubacin. Hence epileptiform manifestations of developmental origin could be prevented in utero, using a transient and drug-based therapeutic protocol.

Biological functions of iduronic acid in chondroitin/dermatan sulfate

The presence of iduronic acid in chondroitin/dermatan sulfate changes the properties of the polysaccharides because it generates a more flexible chain with increased binding potentials. Iduronic acid in chondroitin/dermatan sulfate influences multiple cellular properties, such as migration, proliferation, differentiation, angiogenesis and the regulation of cytokine/growth factor activities. Under pathological conditions such as wound healing, inflammation and cancer, iduronic acid has diverse regulatory functions. Iduronic acid is formed by two epimerases (i.e. dermatan sulfate epimerase 1 and 2) that have different tissue distribution and properties. The role of iduronic acid in chondroitin/dermatan sulfate is highlighted by the vast changes in connective tissue features in patients with a new type of Ehler–Danlos syndrome: adducted thumb-clubfoot syndrome. Future research aims to understand the roles of the two epimerases and their interplay with the sulfotransferases involved in chondroitin sulfate/dermatan sulfate biosynthesis. Furthermore, a better definition of chondroitin/dermatan sulfate functions using different knockout models is needed. In this review, we focus on the two enzymes responsible for iduronic acid formation, as well as the role of iduronic acid in health and disease.

Non-CpG island promoter hypomethylation and miR-149 regulate the expression of SRPX2 in colorectal cancer

Gene silencing by DNA hypermethylation of CpG islands is a well-characterized phenomenon in cancer. The effect of hypomethylation in particular of non-CpG island genes is much less well described. By genome-wide screening, we identified 105 genes in microsatellite stable (MSS) colorectal adenocarcinomas with an inverse correlation (Spearman's ρ ≤ -0.40) between methylation and expression. Of these, 35 (33%) were hypomethylated non-CpG island genes and two of them, APOLD1 (Spearman's ρ = -0.82) and SRPX2 (Spearman's ρ = -0.80) were selected for further analyses. Hypomethylation of both genes were localized events not shared by adjacent genes. A set of 662 FFPE DNA samples not only confirmed that APOLD1 and SRPX2 are hypomethylated in CRC but also revealed hypomethylation to be significantly (p < 0.01) associated with tumors being localized in the left side, CpG island methylator phenotype negative, MSS, BRAF wt, undifferentiated and of adenocarcinoma histosubtype. Demethylation experiments supported SRPX2 being epigenetically regulated via DNA methylation, whereas other mechanisms in addition to DNA methylation seem to be involved in the regulation of APOLD1. We further identified miR-149 as a potential novel post-transcriptional regulator of SRPX2. In carcinoma tissue, miR-149 was downregulated and inversely correlated to SRPX2 (ρ = -0.77). Furthermore, ectopic expression of miR-149 significantly reduced SRPX2 transcript levels. Our study highlights that in colorectal tumors, hypomethylation of non-CpG island-associated promoters deregulate gene expression nearly as frequent as do CpG-island hypermethylation. The hypomethylation of SRPX2 is focal and not part of a large block. Furthermore, it often translates to an increased expression level, which may be modulated by miR-149.

Iduronic acid in chondroitin/dermatan sulfate: biosynthesis and biological function

The ability of chondroitin/dermatan sulfate (CS/DS) to convey biological information is enriched by the presence of iduronic acid. DS-epimerases 1 and 2 (DS-epi1 and 2), in conjunction with DS-4-O-sulfotransferase 1, are the enzymes responsible for iduronic acid biosynthesis and will be the major focus of this review. CS/DS proteoglycans (CS/DS-PGs) are ubiquitously found in connective tissues, basement membranes, and cell surfaces or are stored intracellularly. Such wide distribution reflects the variety of biological roles in which they are involved, from extracellular matrix organization to regulation of processes such as proliferation, migration, adhesion, and differentiation. They play roles in inflammation, angiogenesis, coagulation, immunity, and wound healing. Such versatility is achieved thanks to their variable composition, both in terms of protein core and the fine structure of the CS/DS chains. Excellent reviews have been published on the collective and individual functions of each CS/DS-PG. This short review presents the biosynthesis and functions of iduronic acid-containing structures, also as revealed by the analysis of the DS-epi1- and 2-deficient mouse models.