Sialylation of vasorin by ST3Gal1 facilitates TGF-β1-mediated tumor angiogenesis and progression

Vasorin Exocytosed from Glioma Cells Facilitates Angiogenesis via VEGFR2/AKT Signaling Pathway

Glioma is a highly vascularized tumor of the central nervous system. Angiogenesis plays a predominant role in glioma progression and is considered an important therapeutic target. Our previous study showed that vasorin (VASN), a transmembrane protein, is overexpressed in glioma and promotes angiogenesis; however, the potential mechanism remains unclear. In this study, we found that human vascular endothelial cells (hEC) co-cultured with VASN-overexpressing glioma cells exhibited accelerated migration ability and increased expression of VASN originated from glioma cells. VASN was found in exosomes secreted by glioma cells and could be taken up by hECs. hECs showed more edge filopodia and significantly upregulated expression of endothelial tip cell marker gene and protein levels after co-culture with VASN-overexpressing glioma cells. In clinical glioma tissue and orthotopic transplantation glioma tissue, the vascular density and the number of vascular endothelial cells with a tip cell phenotype in VASN-overexpressed tissues were significantly higher than in tissues with low expression. At the molecular level, VASN interacted with VEGFR2 and caused internalization and autophosphorylation of VEGFR2 protein, and then activated the AKT signaling pathway. Our study collectively reveals the function and mechanism of VASN in facilitating angiogenesis in glioma, providing a new therapeutic target for glioma.

IMPLICATIONS

These findings demonstrate that VASN exocytosed from glioma cells enhanced the migration of vascular endothelial cells by VEGFR2/AKT signaling pathway.

Novel regulatory mechanisms of N-glycan sialylation: Implication of integrin and focal adhesion kinase in the regulation

BACKGROUND

Sialylation of glycoproteins, including integrins, is crucial in various cancers and diseases such as immune disorders. These modifications significantly impact cellular functions and are associated with cancer progression. Sialylation, catalyzed by specific sialyltransferases (STs), has traditionally been considered to be regulated at the mRNA level.

SCOPE OF REVIEW

Recent research has expanded our understanding of sialylation, revealing ST activity changes beyond mRNA level variations. This includes insights into COPI vesicle formation and Golgi apparatus maintenance and identifying specific target proteins of STs that are not predictable through recombinant enzyme assays.

MAJOR CONCLUSIONS

This review summarizes that Golgi-associated pathways largely influence the regulation of STs. GOLPH3, GORAB, PI4K, and FAK have become critical elements in sialylation regulation. Some STs have been revealed to possess specificity for specific target proteins, suggesting the presence of additional, enzyme-specific regulatory mechanisms.

GENERAL SIGNIFICANCE

This study enhances our understanding of the molecular interplay in sialylation regulation, mainly focusing on the role of integrin and FAK. It proposes a bidirectional system where sialylations might influence integrins and vice versa. The diversity of STs and their specific linkages offer new perspectives in cancer research, potentially broadening our understanding of cellular mechanisms and opening avenues for new therapeutic approaches in targeting sialylation pathways.

Integrating spatial transcriptomics and bulk RNA-seq: predicting gene expression with enhanced resolution through graph attention networks

Spatial transcriptomics data play a crucial role in cancer research, providing a nuanced understanding of the spatial organization of gene expression within tumor tissues. Unraveling the spatial dynamics of gene expression can unveil key insights into tumor heterogeneity and aid in identifying potential therapeutic targets. However, in many large-scale cancer studies, spatial transcriptomics data are limited, with bulk RNA-seq and corresponding Whole Slide Image (WSI) data being more common (e.g. TCGA project). To address this gap, there is a critical need to develop methodologies that can estimate gene expression at near-cell (spot) level resolution from existing WSI and bulk RNA-seq data. This approach is essential for reanalyzing expansive cohort studies and uncovering novel biomarkers that have been overlooked in the initial assessments. In this study, we present STGAT (Spatial Transcriptomics Graph Attention Network), a novel approach leveraging Graph Attention Networks (GAT) to discern spatial dependencies among spots. Trained on spatial transcriptomics data, STGAT is designed to estimate gene expression profiles at spot-level resolution and predict whether each spot represents tumor or non-tumor tissue, especially in patient samples where only WSI and bulk RNA-seq data are available. Comprehensive tests on two breast cancer spatial transcriptomics datasets demonstrated that STGAT outperformed existing methods in accurately predicting gene expression. Further analyses using the TCGA breast cancer dataset revealed that gene expression estimated from tumor-only spots (predicted by STGAT) provides more accurate molecular signatures for breast cancer sub-type and tumor stage prediction, and also leading to improved patient survival and disease-free analysis. Availability: Code is available at https://github.com/compbiolabucf/STGAT.

The role of ST3GAL4 in glioma malignancy, macrophage infiltration, and prognostic outcomes

Background

Glioma, a prevalent malignancy of the brain and spinal cord, poses a considerable threat to human health. The association between aberrant sialic acid modification and glioma progression has been suggested, but the precise mechanism is still elusive. ST3GAL4, a sialoglycosyltransferase, is implicated in increased metastatic potential and poor prognosis in various cancers; however, its specific role in glioma requires further elucidation.

Methods

We evaluated ST3GAL4 expression levels and their clinical relevance using the TCGA database, and we assessed immune infiltration via the Tumor Immune Evaluation Resource (TIMER) database. In vitro experiments were performed to determine the effects of ST3GAL4 knockdown on glioma cell malignancy, with additional co-culture assays to assess its impact on macrophage phenotype.

Results

ST3GAL4 expression was markedly elevated in glioma tissues compared to normal brain tissues, with a strong correlation to glioma patient clinical characteristics. Survival analyses and receiver operating characteristic (ROC) curves suggested that ST3GAL4 is a feasible diagnostic and prognostic biomarker for glioma. Knockdown studies revealed that ST3GAL4 inhibition reduces glioma cell line proliferation, migration, and invasion, while causing G1 phase cell cycle arrest. ST3GAL4 appears to mediate glioma progression through extracellular matrix reorganization and EMT signaling pathway activation, further contributing to M2 macrophage polarization and infiltration within the tumor microenvironment.

Conclusion

Our research highlights the critical role of ST3GAL4 in glioma development, positioning it as a promising candidate for diagnostic and therapeutic interventions.

A sialyltransferases-related gene signature serves as a potential predictor of prognosis and therapeutic response for bladder cancer

BACKGROUND

Aberrant glycosylation, catalyzed by the specific glycosyltransferase, is one of the dominant features of cancers. Among the glycosyltransferase subfamilies, sialyltransferases (SiaTs) are an essential part which has close linkages with tumor-associated events, such as tumor growth, metastasis and angiogenesis. Considering the relationship between SiaTs and cancer, the current study attempted to establish an effective prognostic model with SiaTs-related genes (SRGs) to predict patients' outcome and therapeutic responsiveness of bladder cancer.

METHODS

RNA-seq data, clinical information and genomic mutation data were downloaded (TCGA-BLCA and GSE13507 datasets). The comprehensive landscape of the 20 SiaTs was analyzed, and the differentially expressed SiaTs-related genes were screened with "DESeq2" R package. ConsensusClusterPlus was applied for clustering, following with survival analysis with Kaplan-Meier curve. The overall survival related SRGs were determined with univariate Cox proportional hazards regression analysis, and the least absolute shrinkage and selection operator (LASSO) regression analysis was performed to generate a SRGs-related prognostic model. The predictive value was estimated with Kaplan-Meier plot and the receiver operating characteristic (ROC) curve, which was further validated with the constructed nomogram and decision curve.

RESULTS

In bladder cancer tissues, 17 out of the 20 SiaTs were differentially expressed with CNV changes and somatic mutations. Two SiaTs_Clusters were determined based on the expression of the 20 SiaTs, and two gene_Clusters were identified based on the expression of differentially expressed genes between SiaTs_Clusters. The SRGs-related prognostic model was generated with 7 key genes (CD109, TEAD4, FN1, TM4SF1, CDCA7L, ATOH8 and GZMA), and the accuracy for outcome prediction was validated with ROC curve and a constructed nomogram. The SRGs-related prognostic signature could separate patients into high- and low-risk group, where the high-risk group showed poorer outcome, more abundant immune infiltration, and higher expression of immune checkpoint genes. In addition, the risk score derived from the SRGs-related prognostic model could be utilized as a predictor to evaluate the responsiveness of patients to the medical therapies.

CONCLUSIONS

The SRGs-related prognostic signature could potentially aid in the prediction of the survival outcome and therapy response for patients with bladder cancer, contributing to the development of personalized treatment and appropriate medical decisions.

CD31 defines a subpopulation of human adipose-derived regenerative cells with potent angiogenic effects

Cellular heterogeneity represents a major challenge for regenerative treatment using freshly isolated Adipose Derived Regenerative Cells (ADRCs). Emerging data suggest superior efficacy of ADRCs as compared to the ex vivo expanded and more homogeneous ADRCs (= ASCs) for indications involving (micro)vascular deficiency, however, it remains unknown which ADRC cell subtypes account for the improvement. Surprisingly, we found regarding erectile dysfunction (ED) that the number of injected CD31+  ADRCs correlated positively with erectile function 12 months after one bolus of autologous ADRCs. Comprehensive in vitro and ex vivo analyses confirmed superior pro-angiogenic and paracrine effects of human CD31+ enriched ADRCs compared to the corresponding CD31- and parent ADRCs. When CD31+, CD31- and ADRCs were co-cultured in aortic ring- and corpus cavernous tube formation assays, the CD31+  ADRCs induced significantly higher tube development. This effect was corroborated using conditioned medium (CM), while quantitative mass spectrometric analysis suggested that this is likely explained by secretory pro-angiogenic proteins including DKK3, ANGPT2, ANAX2 and VIM, all enriched in CD31+  ADRC CM. Single-cell RNA sequencing showed that transcripts of the upregulated and secreted proteins were present in 9 endothelial ADRC subsets including endothelial progenitor cells in the heterogenous non-cultured ADRCs. Our data suggest that the vascular benefit of using ADRCs in regenerative medicine is dictated by CD31+  ADRCs.

Recent advances in the development of sialyltransferase inhibitors to control cancer metastasis: A comprehensive review

Metastasis accounts for the majority of cancer-associated mortalities, representing a huge health and economic burden. One of the mechanisms that enables metastasis is hypersialylation, characterized by an overabundance of sialylated glycans on the tumor surface, which leads to repulsion and detachment of cells from the original tumor. Once the tumor cells are mobilized, sialylated glycans hijack the natural killer T-cells through self-molecular mimicry and activatea downstream cascade of molecular events that result in inhibition of cytotoxicity and inflammatory responses against cancer cells, ultimately leading to immune evasion. Sialylation is mediated by a family of enzymes known as sialyltransferases (STs), which catalyse the transfer of sialic acid residue from the donor, CMP-sialic acid, onto the terminal end of an acceptor such as N-acetylgalactosamine on the cell-surface. Upregulation of STs increases tumor hypersialylation by up to 60% which is considered a distinctive hallmark of several types of cancers such as pancreatic, breast, and ovarian cancer. Therefore, inhibiting STs has emerged as a potential strategy to prevent metastasis. In this comprehensive review, we discuss the recent advances in designing novel sialyltransferase inhibitors using ligand-based drug design and high-throughput screening of natural and synthetic entities, emphasizing the most successful approaches. We analyse the limitations and challenges of designing selective, potent, and cell-permeable ST inhibitors that hindered further development of ST inhibitors into clinical trials. We conclude by analysing emerging opportunities, including advanced delivery methods which further increase the potential of these inhibitors to enrich the clinics with novel therapeutics to combat metastasis.

Evidence for the expression of vasorin in the human female reproductive tissues

Objective: To investigate the expression and localization of Vasorin (Vasn) in human female reproductive system. Methods: The presence of Vasorin was evaluated by RT-PCR and immunoblotting analyses in patient-derived endometrial, myometrial and granulosa cells (GCs) primary cultures. Immunostaining analyses were performed to detect Vasn localization in primary cultures and in ovarian and uterine tissues. Results: Vasn mRNA was detected in patient-derived endometrial, myometrial and GCs primary cultures without significant differences at the transcript level. Otherwise, immunoblotting analysis showed that Vasn protein levels were significantly higher in GCs than proliferative endometrial stromal cells (ESCs) and myometrial cells. Immunohistochemistry performed in ovarian tissues revealed that Vasn was expressed in the GCs of ovarian follicles at different stages of development with a higher immunostaining signal in mature ovarian follicles such as the antral follicle or on the surface of cumulus oophorus cells than in early-stage follicles. The immunostaining of uterine tissues showed that Vasn was expressed in the proliferative stroma endometrium while it was significantly less expressed in the secretory endometrium. Conversely, no protein immunoreactivity was revealed in health myometrial tissue. Conclusions: Our results revealed the presence of Vasn in the ovary and the endometrium. The pattern of Vasn expression and distribution suggests that this protein may have a role in the regulation of processes such as folliculogenesis, oocyte maturation, and endometrial proliferation.

Mutual regulation between glycosylation and transforming growth factor-β isoforms signaling pathway

Transforming growth factor-beta (TGF-β) superfamily members orchestrate a wide breadth of biological processes. Through Sma and Mad (Smad)-related dependent or noncanonical pathways, TGF-β members involve in the occurrence and development of many diseases such as cancers, fibrosis, autoimmune diseases, cardiovascular diseases and brain diseases. Glycosylation is one kind of the most common posttranslational modifications on proteins or lipids. Abnormal protein glycosylation can lead to protein malfunction and biological process disorder, thereby causing serious diseases. Previously, researchers commonly make comprehensive systematic overviews on the roles of TGF-β signaling in a specific disease or biological process. In recent years, more and more evidences associate glycosylation modification with TGF-β signaling pathway, and we can no longer disengage and ignore the roles of glycosylation from TGF-β signaling to make investigation. In this review, we provide an overview of current findings involved in glycosylation within TGF-βs and theirs receptors, and the interaction effects between glycosylation and TGF-β subfamily signaling, concluding that there is an intricate mutual regulation between glycosylation and TGF-β signaling, hoping to present the glycosylation regulatory patterns that concealed in TGF-βs signaling pathways.

VASN promotes colorectal cancer progression by activating the YAP/TAZ and AKT signaling pathways via YAP

Colorectal cancer (CRC) is one of the most common gastrointestinal malignancies. Vasorin (VASN) has been reported to be critical in tumor development and angiogenesis. However, VASN has not been reported in CRC, and its role is unclear. In this study, VASN expression is upregulated in CRC compared with the normal tissues, and VASN expression positively correlates with N stage and poor overall survival by analysis of different datasets and 32 CRC clinicopathologic samples. Overexpression of VASN significantly promotes CRC cell progression, including proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT), while knockdown of VASN inhibits CRC progression. We found that VASN was associated with the YAP/TAZ and PI3K/AKT pathways by gene set enrichment analysis (GSEA) and gene ontology (GO) analysis. Notably, western blotting, immunofluorescence staining and co-immunofluorescence (co-IP) confirmed that VASN could interact with YAP and activate the YAP/TAZ and PTEN/PI3K/AKT pathways, and knockdown of YAP reversed this effect. Importantly, our findings indicate that VASN interacts with YAP to inhibit YAP phosphorylation and stimulates CRC proliferation, migration, and invasion through activation of the YAP/TAZ-TEAD target gene CTGF and PTEN/PI3K/AKT pathways. Our results also show that knockdown of YAP reverses the cellular phenotype induced by increased VASN. In conclusion, our study reveals that VASN acts as an oncogene to stimulate tumor progression in CRC, providing new insights into the molecular mechanisms of CRC development and representing a possible novel biomarker for CRC.

TGF-β at the crossroads of multiple prognosis in breast cancer, and beyond

Transforming growth factor β (TGF-β), a pluripotent cytokine and a multifunctional growth factor has a crucial role in varied biological mechanisms like invasion, migration, epithelial-mesenchymal transition, apoptosis, wound healing, and immunosuppression. Moreover, it also has an imperative role both in normal mammary gland development as well as breast carcinogenesis. TGF-β has shown to have a paradoxical role in breast carcinogenesis, by transitioning from a growth inhibitor to a growth promoter with the disease advancement. The inter-communication and crosstalk of TGF-β with different signaling pathways has strengthened the likelihood to explore it as a comprehensive biomarker. In the last two decades, TGF-β has been studied extensively and has been found to be a promising biomarker for early detection, disease monitoring, treatment selection, and tumor progression making it beneficial for disease management. In this review, we focus on the signaling pathways and biological activities of the TGF-β family in breast cancer pathogenesis and its role as a circulatory and independent biomarker for breast cancer progression and metastasis. Moreover, this review highlights TGF-β as a drug target, and the underlying mechanisms through which it is involved in tumorigenesis that will aid in the development of varied therapies targeting the different stages of breast cancer.

Aberrant Sialylation in Cancer: Therapeutic Opportunities

The surface of every eukaryotic cell is coated in a thick layer of glycans that acts as a key interface with the extracellular environment. Cancer cells have a different ‘glycan coat’ to healthy cells and aberrant glycosylation is a universal feature of cancer cells linked to all of the cancer hallmarks. This means glycans hold huge potential for the development of new diagnostic and therapeutic strategies. One key change in tumour glycosylation is increased sialylation, both on N-glycans and O-glycans, which leads to a dense forest of sialylated structures covering the cell surface. This hypersialylation has far-reaching consequences for cancer cells, and sialylated glycans are fundamental in tumour growth, metastasis, immune evasion and drug resistance. The development of strategies to inhibit aberrant sialylation in cancer represents an important opportunity to develop new therapeutics. Here, I summarise recent advances to target aberrant sialylation in cancer, including the development of sialyltransferase inhibitors and strategies to inhibit Siglecs and Selectins, and discuss opportunities for the future.

Vasorin Deletion in C57BL/6J Mice Induces Hepatocyte Autophagy through Glycogen-Mediated mTOR Regulation

Abnormal vasorin (Vasn) expression occurs in multiple diseases, particularly liver cancers. Vasn knockout (KO) in mice causes malnutrition, a shortened life span, and decreased physiological functions. However, the causes and underlying mechanisms remain unknown. Here, we established Vasn KO C57BL/6J mice by using the CRISPR/Cas9 system. The animals were weighed, and histology, immunohistochemistry, electronic microscopy, and liver function tests were used to examine any change in the livers. Autophagy markers were detected by Western blotting. MicroRNA (miRNA) sequencing was performed on liver samples and analyses to study the signaling pathway altered by Vasn KO. Significant reductions in mice body and liver weight, accompanied by abnormal liver function, liver injury, and reduced glycogen accumulation in hepatocytes, were observed in the Vasn KO mice. The deficiency of Vasn also significantly increased the number of autophagosomes and the expression of LC3A/B-II/I but decreased SQSTM1/p62 levels in hepatocytes, suggesting aberrant activation of autophagy. Vasn deficiency inhibited glycogen-mediated mammalian target of rapamycin (mTOR) phosphorylation and activated Unc-51-like kinase 1 (ULK1) signaling, suggesting that Vasn deletion upregulates hepatocyte autophagy through the mTOR-ULK1 signaling pathway as a possible cause of diminished life span and health. Our results indicate that Vasn is required for the homeostasis of liver glycogen metabolism upstream of hepatocyte autophagy, suggesting research values for regulating Vasn in pathways related to liver physiology and functions. Overall, this study provides new insight into the role of Vasn in liver functionality.

Comprehensive landscape of the ST3GAL family reveals the significance of ST3GAL6-AS1/ST3GAL6 axis on EGFR signaling in lung adenocarcinoma cell invasion

Sialylation aberration has been implicated in lung cancer development by altering signaling pathways. Hence, it is urgent to identify key sialyltransferases in the development of lung adenocarcinoma (LUAD), which is a common malignant subtype of non-small cell lung cancer. Herein, by systematically investigating the expression levels of ST3GAL family members in several public databases, we consistently found the frequent downregulation of ST3GAL6 in LUAD samples. Its downregulation is significantly negatively associated with stage, and significantly reduced in proximal-proliferative molecular subtype and predicts poor clinical outcomes. By protein–protein interaction network analysis and validation, we found that ST3GAL6 deficiency promotes LUAD cell invasiveness with the activated EGFR/MAPK signaling, accompanied by the elevated expression levels of matrix metalloproteinases 2 and 9, which can be partially reversed by EGFR inhibitor, gefitinib. Additionally, the ST3GAL6 level was positively regulated by ST3GAL6-AS1, an antisense long non-coding RNA to its host gene. The downregulation of ST3GAL6-AS1 also heralds a worse prognosis in LUAD patients and promotes LUAD cell invasiveness, recapitulating the function of its host gene, ST3GAL6. Altogether, ST3GAL6-AS1-regulated ST3GAL6 is a frequently downregulated sialyltransferase in LUAD patients and negatively regulates EGFR signaling, which can serve as a promising independent prognostic marker in LUAD patients.

Prognostic Signature and Therapeutic Value Based on Membrane Lipid Biosynthesis-Related Genes in Breast Cancer

There is a need to improve diagnostic and therapeutic approaches to enhance the prognosis of breast cancer, the most common malignancy worldwide. Membrane lipid biosynthesis is a hot biological pathway in current cancer research. It is unclear whether membrane lipid biosynthesis is involved in the prognosis of BRCA. With LASSO regression, a 14-gene prediction model was constructed using data from the TCGA-BRCA cohort. The prediction model includes GPAA1, PIGF, ST3GAL1, ST6GALNAC4, PLPP2, ELOVL1, HACD1, SGPP1, PRKD2, VAPB, CERS2, SGMS2, ALDH3B2, and HACD3. BRCA patients from the TCGA-BRCA cohort were divided into two risk subgroups based on the model. Kaplan–Meier survival curves showed that patients with lower risk scores had significantly improved overall survival (P=2.49e − 09). In addition, risk score, age, stage, and TNM classification were used to predict mortality in BRCA patients. In addition, the 14 genes in the risk model were analyzed for gene variation, methylation level, drug sensitivity, and immune cell infiltration, and the miRNA-mRNA network was constructed. Afterward, the THPA website then analyzed the protein expression of 14 of these risk model genes in normal and pathological BRCA tissues. In conclusion, the membrane lipid biosynthesis-related risk model and nomogram can be used to predict BRCA clinical prognosis.

Functional analysis of GCNT3 for cell migration and EMT of castration-resistant prostate cancer cells

Castration-resistant prostate cancer (CRPC) is a malignant tumor that is resistant to androgen deprivation therapy. Treatments for CRPC are limited, and no diagnostic markers are currently available. O-glycans are known to play an important role in cell proliferation, migration, invasion, and metastasis of cancer cells. However, the differences in the O-glycan expression profiles for normal prostate cancer (PCa) cells compared to CRPC cells have not yet been investigated. In this study, the saccharide primer method was employed to analyze the O-glycans expressed in CRPC cells. Expression levels of core 4-type O-glycans were significantly increased in CRPC cells. Furthermore, the expression level of N-Acetylglucosaminyltransferase 3 (GCNT3), a core 4-type O-glycan synthase gene, was increased in CRPC cells. The expression of core 4-type O-glycans and GCNT3 was presumed to be regulated by androgen deprivation. GCNT3 knockdown induced cell migration and epithelial-mesenchymal transition (EMT). These observations elucidate the mechanism of acquisition of castration resistance in PCa and offer new possibilities for the development of diagnostic markers and therapeutic targets in the treatment of PCa.

Overlapping and unique substrate specificities of ST3GAL1 and 2 during hematopoietic and megakaryocytic differentiation

ST3GAL1 and ST3GAL2 have both overlapping and unique substrate specificities in O-glycan sialylation during megakaryopoiesis.

O-glycan sialylation is dispensable for MK production but indispensable for MK proplatelet formation.

Although the sialyltransferases ST3GAL1 and ST3GAL2 are known to transfer sialic acid to the galactose residue of type III disaccharides (Galβ1,3GalNAc) in vitro, sialylation of O-linked glycosylated proteins in living cells has been largely attributed to ST3GAL1. To examine the role of ST3GAL2 in O-sialylation, we examined its expression during differentiation of human-induced pluripotent stem cells (iPSCs) into hematopoietic progenitor cells (HPCs) and megakaryocytes (MKs). ST3GAL1 and ST3GAL2 each became highly expressed during the differentiation of iPSCs to HPCs but decreased markedly in their expression upon differentiation into MKs, suggesting coordination of expression during megakaryopoiesis. To further delineate their role in these processes, we generated ST3GAL1-, ST3GAL2-, and doubly deficient human iPSC lines. Binding of the peanut agglutinin lectin, which reports the presence of unsialylated Galβ1,3GalNAc glycan chains, was strongly increased in HPCs and MKs derived from double-knockout iPSCs and remained moderately increased in cells lacking either one of these sialyltransferases, demonstrating that both can serve as functional cellular O-glycan sialyltransferases. Interestingly, the HPC markers CD34 and CD43, as well as MK membrane glycoprotein (GP) GPIbα, were identified as major GP substrates for ST3GAL1 and ST3GAL2. In contrast, O-sialylation of GPIIb relied predominantly on the expression of ST3GAL2. Finally, although disruption of ST3GAL1 and ST3GAL2 had little impact on MK production, their absence resulted in dramatically impaired MK proplatelet formation. Taken together, these data establish heretofore unknown physiological roles for ST3GAL1 and ST3GAL2 in O-linked glycan sialylation in hemato- and megakaryocytopoiesis.

Significance of combined TGF‑β1 and survivin expression on the prognosis of patients with triple‑negative breast cancer

Compared with other types of breast cancer, triple-negative breast cancer (TNBC) has the characteristics of rapid progression, a lack of specific molecular targets for treatment and a poor prognosis. However, based on previously published studies, TGF-β1 and survivin are potentially meaningful for the prognosis of patients with TNBC. The present study was therefore designed to measure and compare the expression of transforming growth factor-β1 (TGF-β1) and survivin in tissue samples of TNBC and non-TNBC patients in order to evaluate their ability as prognostic indicators. In total, 90 TNBC and 52 non-TNBC tissue specimens were selected, following which immunohistochemistry was used to detect the expression of TGF-β1 and survivin in the cancer tissues. Subsequently, the potential association between the expression levels of these two proteins and the clinicopathological variables was analyzed. The expression levels of TGF-β1 and survivin in TNBC tissues were found to be significantly higher compared with those in the non-TNBC tissues. In addition, the results of the present study demonstrated that TGF-β1 expression was positively associated with survivin expression in the TNBC samples, but no significant correlation was found between TGF-β1 and survivin expression in the non-TNBC samples. Kaplan-Meier (K-M) analysis was performed to assess the levels of TGF-β1 and survivin in regard to patient survival, and univariate and multivariate Cox analyses of TGF-β1 and survivin protein expression were performed to analyze the overall survival (OS) and progression-free survival (PFS) rates of patients with TNBC and non-TNBC. Although multivariate Cox analysis demonstrated that neither TGF-β1 or survivin were independent prognostic predictors of TNBC or non-TNBC, results of the K-M curve revealed that patients with TNBC with TGF-β1- and survivin-positive breast cancer exhibited shorter OS and PFS times. Multivariate Cox analysis demonstrated that in patients with TNBC, the combined expression of TGF-β1 and survivin may yield additional prognostic information, compared with patients with non-TNBC.

Analysis of Tumor Glycosylation Characteristics and Implications for Immune Checkpoint Inhibitor’s Efficacy for Breast Cancer

The alterations of glycosylation, which is a common post-translational modification of proteins, have been acknowledged as key events in breast cancer (BC) oncogenesis and progression. The aberrant expression of glycosyltransferases leads to aberrant glycosylation patterns, posing the diagnostic potential in BC outcomes. The present study aims to establish a glycosyltransferase-based signature to predict BC prognosis and response to immune checkpoint inhibitors. We firstly screened 9 glycosyltransferase genes from The Cancer Genome Atlas (TCGA) database and accordingly established a glyco-signature for predicting the prognosis in BC patients. Patients with BC were successfully divided into high-risk and low-risk groups based on the median cutoff point for risk scores in this signature. Next, the combinational analyses of univariate and multivariate Cox regression, Kaplan–Meier, and receiver operating characteristic (ROC) curves were used to prove that this glyco-signature possessed excellent predictive performance for prognosis of BC patients, as the high-risk group possessed worse outcomes, in comparison to the low-risk group. Additionally, the Gene Set Enrichment Analysis (GSEA) and immunologic infiltration analysis were adopted and indicated that there was a more immunosuppressive state in the high-risk group than that in the low-risk group. The clinical sample validation verified that glycosyltransferase genes were differentially expressed in patients in the low- and high-risk groups, while the biomarkers of antitumor M1 macrophages were increased and N-glycosyltransferase STT3A decreased in the low-risk group. The final in vitro assay showed that the silencing of STT3A suppressed the proliferation and migration of BC cells. Collectively, our well-constructed glyco-signature is able to distinguish the high- and low-risk groups and accordingly predict BC prognosis, which will synergistically promote the prognosis evaluation and provide new immunotherapeutic targets for combating BC.

Role of vasorin, an anti-apoptotic, anti-TGF-β and hypoxia-induced glycoprotein in the trabecular meshwork cells and glaucoma

Glaucoma, one of the leading causes of irreversible blindness, is commonly associated with elevated intraocular pressure due to impaired aqueous humour (AH) drainage through the trabecular meshwork. The aetiological mechanisms contributing to impaired AH outflow, however, are poorly understood. Here, we identified the secreted form of vasorin, a transmembrane glycoprotein, as a common constituent of human AH by mass spectrometry and immunoblotting analysis. ELISA assay revealed a significant but marginal decrease in vasorin levels in the AH of primary open‐angle glaucoma patients compared to non‐glaucoma cataract patients. Human trabecular meshwork (HTM) cells were confirmed to express vasorin, which has been shown to possess anti‐apoptotic and anti‐TGF‐β activities. Treatment of HTM cells with vasorin induced actin stress fibres and focal adhesions and suppressed TGF‐β2‐induced SMAD2/3 activation in HTM cells. Additionally, cobalt chloride‐induced hypoxia stimulated a robust elevation in vasorin expression, and vasorin suppressed TNF‐α‐induced cell death in HTM cells. Taken together, these findings reveal the importance of vasorin in maintenance of cell survival, inhibition of TGF‐β induced biological responses in TM cells, and the decreasing trend in vasorin levels in the AH of glaucoma patients suggests a plausible role for vasorin in the pathobiology of ocular hypertension and glaucoma.

Abnormal sialylation and fucosylation of saliva glycoproteins: Characteristics of lung cancer-specific biomarkers

Dysregulated surface glycoproteins play an important role in tumor cell proliferation and progression. Abnormal glycosylation of these glycoproteins may activate tumor signal transduction and lead to tumor development. The tumor microenvironment alters its molecular composition, some of which regulate protein glycosylation biosynthesis. The glycosylation of saliva proteins in lung cancer patients is different from healthy controls, in which the glycans of cancer patients are highly sialylated and hyperfucosylated. Most studies have shown that O-glycans from cancer are truncated O-glycans, while N-glycans contain fucoses and sialic acids. Because glycosylation analysis is challenging, there are few reports on how glycosylation of saliva proteins is related to the occurrence or progression of lung cancer. In this review, we discussed glycoenzymes involved in protein glycosylation, their changes in tumor microenvironment, potential tumor biomarkers present in body fluids, and abnormal glycosylation of saliva or lung glycoproteins. We further explored the effect of glycosylation changes on tumor signal transduction, and emphasized the role of receptor tyrosine kinases in tumorigenesis and metastasis.

Vasorin deficiency leads to cardiac hypertrophy by targeting MYL7 in young mice

Vasorin (VASN) is an important transmembrane protein associated with development and disease. However, it is not clear whether the death of mice with VASN deficiency (VASN^-/- ) is related to cardiac dysfunction. The aim of this research was to ascertain whether VASN induces pathological cardiac hypertrophy by targeting myosin light chain 7 (MYL7). VASN^-/- mice were produced by CRISPR/Cas9 technology and inbreeding. PCR amplification, electrophoresis, real-time PCR and Western blotting were used to confirm VASN deficiency. Cardiac hypertrophy was examined by blood tests, histological analysis and real-time PCR, and key downstream factors were identified by RNA sequencing and real-time PCR. Western blotting, immunohistochemistry and electron microscopy analysis were used to confirm the downregulation of MYL7 production and cardiac structural changes. Our results showed that sudden death of VASN^-/- mice occurred 21-28 days after birth. The obvious increases in cardiovascular risk, heart weight and myocardial volume and the upregulation of hypertrophy marker gene expression indicated that cardiac hypertrophy may be the cause of death in young VASN^-/- mice. Transcriptome analysis revealed that VASN deficiency led to MYL7 downregulation, which induced myocardial structure abnormalities and disorders. Our results revealed a pathological phenomenon in which VASN deficiency may lead to cardiac hypertrophy by downregulating MYL7 production. However, more research is necessary to elucidate the underlying mechanism.

SHP2 inhibition enhances the anticancer effect of Osimertinib in EGFR T790M mutant lung adenocarcinoma by blocking CXCL8 loop mediated stemness

BACKGROUND

Additional epidermal growth factor receptor (EGFR) mutations confer the drug resistance to generations of EGFR targeted tyrosine kinase inhibitor (EGFR-TKI), posing a major challenge to developing effective treatment of lung adenocarcinoma (LUAD). The strategy of combining EGFR-TKI with other synergistic or sensitizing therapeutic agents are considered a promising approach in the era of precision medicine. Moreover, the role and mechanism of SHP2, which is involved in cell proliferation, cytokine production, stemness maintenance and drug resistance, has not been carefully explored in lung adenocarcinoma (LUAD).

METHODS

To evaluate the impact of SHP2 on the efficacy of EGFR T790M mutant LUAD cells to Osimertinib, SHP2 inhibition was tested in Osimertinib treated LUAD cells. Cell proliferation and stemness were tested in SHP2 modified LUAD cells. RNA sequencing was performed to explore the mechanism of SHP2 promoted stemness.

RESULTS

This study demonstrated that high SHP2 expression level correlates with poor outcome of LUAD patients, and SHP2 expression is enriched in Osimertinib resistant LUAD cells. SHP2 inhibition suppressed the cell proliferation and damaged the stemness of EGFR T790M mutant LUAD. SHP2 facilitates the secretion of CXCL8 cytokine from the EGFR T790M mutant LUAD cells, through a CXCL8-CXCR1/2 positive feedback loop that promotes stemness and tumorigenesis. Our results further show that SHP2 mediates CXCL8-CXCR1/2 feedback loop through ERK-AKT-NFκB and GSK3β-β-Catenin signaling in EGFR T790M mutant LUAD cells.

CONCLUSIONS

Our data revealed that SHP2 inhibition enhances the anti-cancer effect of Osimertinib in EGFR T790M mutant LUAD by blocking CXCL8-CXCR1/2 loop mediated stemness, which may help provide an alternative therapeutic option to enhance the clinical efficacy of osimertinib in EGFR T790M mutant LUAD patients.

Multiplexed engineering glycosyltransferase genes in CHO cells via targeted integration for producing antibodies with diverse complex-type N-glycans

Therapeutic antibodies are decorated with complex-type N-glycans that significantly affect their biodistribution and bioactivity. The N-glycan structures on antibodies are incompletely processed in wild-type CHO cells due to their limited glycosylation capacity. To improve N-glycan processing, glycosyltransferase genes have been traditionally overexpressed in CHO cells to engineer the cellular N-glycosylation pathway by using random integration, which is often associated with large clonal variations in gene expression levels. In order to minimize the clonal variations, we used recombinase-mediated-cassette-exchange (RMCE) technology to overexpress a panel of 42 human glycosyltransferase genes to screen their impact on antibody N-linked glycosylation. The bottlenecks in the N-glycosylation pathway were identified and then released by overexpressing single or multiple critical genes. Overexpressing B4GalT1 gene alone in the CHO cells produced antibodies with more than 80% galactosylated bi-antennary N-glycans. Combinatorial overexpression of B4GalT1 and ST6Gal1 produced antibodies containing more than 70% sialylated bi-antennary N-glycans. In addition, antibodies with various tri-antennary N-glycans were obtained for the first time by overexpressing MGAT5 alone or in combination with B4GalT1 and ST6Gal1. The various N-glycan structures and the method for producing them in this work provide opportunities to study the glycan structure-and-function and develop novel recombinant antibodies for addressing different therapeutic applications.

Aberrant Sialylation in Cancer: Biomarker and Potential Target for Therapeutic Intervention?

Simple Summary

Sialylation is a post-translational modification that consists in the addition of sialic acid to growing glycan chains on glycoproteins and glycolipids. Aberrant sialylation is an established hallmark of several types of cancer, including breast, ovarian, pancreatic, prostate, colorectal and lung cancers, melanoma and hepatocellular carcinoma. Hypersialylation can be the effect of increased activity of sialyltransferases and results in an excess of negatively charged sialic acid on the surface of cancer cells. Sialic acid accumulation contributes to tumor progression by several paths, including stimulation of tumor invasion and migration, and enhancing immune evasion and tumor cell survival. In this review we explore the mechanisms by which sialyltransferases promote cancer progression. In addition, we provide insights into the possible use of sialyltransferases as biomarkers for cancer and summarize findings on the development of sialyltransferase inhibitors as potential anti-cancer treatments.

Abstract

Sialylation is an integral part of cellular function, governing many biological processes including cellular recognition, adhesion, molecular trafficking, signal transduction and endocytosis. Sialylation is controlled by the levels and the activities of sialyltransferases on glycoproteins and lipids. Altered gene expression of these enzymes in cancer yields to cancer-specific alterations of glycoprotein sialylation. Mounting evidence indicate that hypersialylation is closely associated with cancer progression and metastatic spread, and can be of prognostic significance in human cancer. Aberrant sialylation is not only a result of cancer, but also a driver of malignant phenotype, directly impacting key processes such as tumor cell dissociation and invasion, cell-cell and cell-matrix interactions, angiogenesis, resistance to apoptosis, and evasion of immune destruction. In this review we provide insights on the impact of sialylation in tumor progression, and outline the possible application of sialyltransferases as cancer biomarkers. We also summarize the most promising findings on the development of sialyltransferase inhibitors as potential anti-cancer treatments.

Transmembrane and coiled-coil domain family 3 (TMCC3) regulates breast cancer stem cell and AKT activation

Cancer stem cells (CSC) play a pivotal role in cancer metastasis and resistance to therapy. Previously, we compared the phosphoproteomes of breast cancer stem cells (BCSCs) enriched subpopulation and non-BCSCs sorted from breast cancer patient-derived xenograft (PDX), and identified a function unknown protein, transmembrane and coiled-coil domain family 3 (TMCC3) to be a potential enrichment marker for BCSCs. We demonstrated greater expression of TMCC3 in BCSCs than non-BCSCs and higher expression of TMCC3 in metastatic lymph nodes and lungs than in primary tumor of breast cancer PDXs. TMCC3 silencing suppressed mammosphere formation, ALDH activity and cell migration in vitro, along with reduced tumorigenicity and metastasis in vivo. Mechanistically, we found that AKT activation was reduced by TMCC3 silencing, but enhanced by TMCC3 overexpression. We further demonstrated that TMCC3 interacted directly with AKT through its 1-153 a.a. domain by cell-free biochemical assay in vitro and co-immunoprecipitation and interaction domain mapping assays in vivo. Based on domain truncation studies, we showed that the AKT-interacting domain of TMCC3 was essential for TMCC3-induced AKT activation, self-renewal, and metastasis. Clinically, TMCC3 mRNA expression in 202 breast cancer specimens as determined by qRT-PCR assay showed that higher TMCC3 expression correlated with poorer clinical outcome of breast cancer, including early-stage breast cancer. Multivariable analysis identified TMCC3 expression as an independent risk factor for survival. These findings suggest that TMCC3 is crucial for maintenance of BCSCs features through AKT regulation, and TMCC3 expression has independent prognostic significance in breast cancer. Thus, TMCC3 may serve as a new target for therapy directed against CSCs.

Kolaviron Ameliorates 7, 12-Dimethylbenzanthracene - Induced Mammary Damage in Female Wistar Rats

BACKGROUND

Kolaviron (KV) is a flavonoid rich portion obtained from Garcinia kola seeds with a number of reported pharmacological effects. However, its ameliorative effects on 7,12-Dimethylbenzanthracene (DMBA)-induced mammary damage has not been fully investigated, despite the reported use of the seeds in the treatment of inflammatory related disorders.

OBJECTIVE

To evaluate the ameliorative effects of KV on DMBA-induced mammary damage in female Wistar rats.

METHODS

Forty-nine (49) female Wistar rats were randomly assigned into seven groups of seven rats each. DMBA was administered orally to rats in five of the groups as a single dose of 80 mg/kg body wt while the remaining two groups received the vehicle. The rats were palpated weekly for 3 months to monitor tumor formation. After 3 months of DMBA administration, 1 ml of blood was collected to assay for estrogen receptor- α (ER-α) level. Thereafter, the vehicle (dimethyl sulfoxide) was daily administered to the negative control and positive control groups for the 14 days duration of the experiment while three groups were each given a daily oral dose of 50, 100 and 200 mg/kg body wt of KV for the duration of the experiment. The last DMBA-induced group received 10 mg/kg body wt of the standard drug tamoxifen twice in a week and the remaining DMBA-free group received 200 mg/kg body wt KV. Subsequently, the animals were humanly sacrificed and ER-α, sialic acids, sialidase, sialyltransferase levels were assay for in blood and mammary tissues followed by histopathological examinations.

RESULTS

Significantly higher levels of estrogen receptor-α (ER-α), formation of lobular neoplastic cells, epithelial hyperplasia, lymphocyte infiltration and increased sialylation were detected in DMBA-induced rats. Treatment with KV at 50, 100 and 200 mg/kg body weight resulted in a significant (p<0.05) decrease in ER-α level, significantly (p<0.05) lower free serum sialic acid (21.1%), total sialic acid level of the mammary tissue (21.57%), sialyltransferase activity (30.83%) as well as mRNA level of the sialyltransferase gene (ST3Gal1) were observed after KV interventions.

CONCLUSION

The findings suggest that KV could be further explored in targeting DMBA-induced mammary damage implicated in mammary carcinogenesis.

Recent advances in understanding the roles of sialyltransferases in tumor angiogenesis and metastasis

Abnormal glycosylation is a common characteristic of cancer cells and there is a lot of evidence that glycans can regulate the biological behavior of tumor cells. Sialylation modification, a form of glycosylation modification, plays an important role in cell recognition, cell adhesion and cell signal transduction. Abnormal sialylation on the surface of tumor cells is related to tumor migration and invasion, with abnormal expression of sialyltransferases being one of the main causes of abnormal sialylation. Recent studies provide a better understanding of the importance of the sialyltransferases, and how they influences cancer cell angiogenesis, adhesion and Epithelial-Mesenchymal Transition (EMT). The present review will provide a direction for future studies in determining the roles of sialyltransferases in cancer metastasis, and abnormal sialyltransferases are likely to be potential biomarkers for cancer.

Sialylation of CD55 by ST3GAL1 Facilitates Immune Evasion in Cancer

Altered glycosylations, which are associated with expression and activities of glycosyltransferases, can dramatically affect the function of glycoproteins and modify the behavior of tumor cells. ST3GAL1 is a sialyltransferase that adds sialic acid to core 1 glycans, thereby terminating glycan chain extension. In breast carcinomas, overexpression of ST3GAL1 promotes tumorigenesis and correlates with increased tumor grade. In pursuing the role of ST3GAL1 in breast cancer using ST3GAL1-siRNA to knockdown ST3GAL1, we identified CD55 to be one of the potential target proteins of ST3GAL1. CD55 is an important complement regulatory protein, preventing cells from complement-mediated cytotoxicity. CD55 had one N-linked glycosylation site in addition to a Ser/Thr-rich domain, which was expected to be heavily O-glycosylated. Detailed analyses of N- and O-linked oligosaccharides of CD55 released from scramble or ST3GAL1 siRNA-treated breast cancer cells by tandem mass spectrometry revealed that the N-glycan profile was not affected by ST3GAL1 silencing. The O-glycan profile of CD55 demonstrated a shift in abundance to nonsialylated core 1 and monosialylated core 2 at the expense of the disialylated core 2 structure after ST3GAL1 silencing. We also demonstrated that O-linked desialylation of CD55 by ST3GAL1 silencing resulted in increased C3 deposition and complement-mediated lysis of breast cancer cells and enhanced sensitivity to antibody-dependent cell-mediated cytotoxicity. These data demonstrated that ST3GAL1-mediated O-linked sialylation of CD55 acts like an immune checkpoint molecule for cancer cells to evade immune attack and that inhibition of ST3GAL1 is a potential strategy to block CD55-mediated immune evasion.

Don't sugarcoat it: How glycocalyx composition influences cancer progression

Buffone and Weaver discuss how the structure of the backbones and glycans of the tumor glycocalyx governs cell–matrix interactions and directs cancer progression.

Mechanical interactions between tumors and the extracellular matrix (ECM) of the surrounding tissues have profound effects on a wide variety of cellular functions. An underappreciated mediator of tumor–ECM interactions is the glycocalyx, the sugar-decorated proteins and lipids that act as a buffer between the tumor and the ECM, which in turn mediates all cell-tissue mechanics. Importantly, tumors have an increase in the density of the glycocalyx, which in turn increases the tension of the cell membrane, alters tissue mechanics, and drives a more cancerous phenotype. In this review, we describe the basic components of the glycocalyx and the glycan moieties implicated in cancer. Next, we examine the important role the glycocalyx plays in driving tension-mediated cancer cell signaling through a self-enforcing feedback loop that expands the glycocalyx and furthers cancer progression. Finally, we discuss current tools used to edit the composition of the glycocalyx and the future challenges in leveraging these tools into a novel tractable approach to treat cancer.

The expression and functional analysis of the sialyl-T antigen in prostate cancer

Aberrant glycosylation is a featured characteristic of cancer and plays a role in cancer pathology; thus an understanding of the compositions and functions of glycans is critical for discovering diagnostic biomarkers and therapeutic targets for cancer. In this study, we used MALDI-TOF-MS analysis to determine the O-glycan profiles of prostate cancer cells metastasized to bone (PC-3), brain (DU145), lymph node (LNCaP), and vertebra (VCaP) in comparison to immortalized RWPE-1 cells derived from normal prostatic tissue. Prostate cancer (CaP) cells exhibited an elevation of simple/short O-glycans, with a reduction of complex O-glycans, increased O-glycan sialylation and decreased fucosylation. Core 1 sialylation was increased dramatically in all CaP cells, and especially in PC-3 cells. The expression of Neu5Acα2-3Galβ1-3GalNAc- (sialyl-3T antigen) which is the product of α2,3-sialyltransferase-I (ST3Gal-I) was substantially increased. We therefore focused on exploring the possible function of ST3Gal-I in PC-3 cells. ST3Gal-I silencing studies showed that ST3Gal-I was associated with PC-3 cell proliferation, migration and apoptosis. Further in vivo studies demonstrated that down regulation of ST3Gal-I reduced the tumor size in xenograft mouse model, indicating that sialyl-3T can serve as a biomarker for metastatic prostate cancer prognosis, and that ST3Gal-I could be a target for therapeutic intervention in cancer treatment.

How glycosylation affects glycosylation: the role of N-glycans in glycosyltransferase activity

N-glycosylation is one of the most important posttranslational modifications of proteins. It plays important roles in the biogenesis and functions of proteins by influencing their folding, intracellular localization, stability and solubility. N-glycans are synthesized by glycosyltransferases, a complex group of ubiquitous enzymes that occur in most kingdoms of life. A growing body of evidence shows that N-glycans may influence processing and functions of glycosyltransferases, including their secretion, stability and substrate/acceptor affinity. Changes in these properties may have a profound impact on glycosyltransferase activity. Indeed, some glycosyltransferases have to be glycosylated themselves for full activity. N-glycans and glycosyltransferases play roles in the pathogenesis of many diseases (including cancers), so studies on glycosyltransferases may contribute to the development of new therapy methods and novel glycoengineered enzymes with improved properties. In this review, we focus on the role of N-glycosylation in the activity of glycosyltransferases and attempt to summarize all available data about this phenomenon.

Aberrant sialylation in ovarian cancers

Sialylation (the covalent addition of sialic acid to the terminal end of glycoproteins or glycans), tightly regulated cell- and microenvironment-specific process and orchestrated by sialyltransferases and sialidases (neuraminidases) family, is one of the posttranslational modifications, which plays an important biological role in the maintenance of normal physiology and involves many pathological dysfunctions. Glycans have roles in all the cancer hallmarks, referring to capabilities acquired during all steps of cancer development to initiate malignant transformation (a driver of a malignant genotype), enable cancer cells to survive, proliferate, and metastasize (a consequence of a malignant phenotype), which includes sustaining proliferative signaling, evading growth suppressor, resisting cell apoptosis, enabling replicative immortality, inducing angiogenesis, reprogramming of energy metabolism, evading tumor destruction, accumulating inflammatory microenvironment, and activating invasion and accelerating metastases. Regarding the important role of altered sialylation of cancers, further knowledge about the initiation and the consequences of altered sialylation pattern in tumor cells is needed, because all may offer a better chance for developing novel therapeutic strategy. In this review, we would like to update alteration of sialylation in ovarian cancers.

Biological Functions and Analytical Strategies of Sialic Acids in Tumor

Sialic acids, a subset of nine carbon acidic sugars, often exist as the terminal sugars of glycans on either glycoproteins or glycolipids on the cell surface. Sialic acids play important roles in many physiological and pathological processes via carbohydrate-protein interactions, including cell-cell communication, bacterial and viral infections. In particular, hypersialylation in tumors, as well as their roles in tumor growth and metastasis, have been widely described. Recent studies have indicated that the aberrant sialylation is a vital way for tumor cells to escape immune surveillance and keep malignance. In this article, we outline the present state of knowledge on the metabolic pathway of human sialic acids, the function of hypersialylation in tumors, as well as the recent labeling and analytical techniques for sialic acids. It is expected to offer a brief introduction of sialic acid metabolism and provide advanced analytical strategies in sialic acid studies.

Vasorin stimulates malignant progression and angiogenesis in glioma

Glioma, the most common human primary brain tumor, is characterized by invasive capabilities and angiogenesis. Vasorin (VASN), a transmembrane protein, is reported to be associated with vascular injury repair and is overexpressed in some human tumors. However, its role in tumor progression and angiogenesis in glioma is unknown. In this study, VASN was shown to be overexpressed in high‐grade gliomas, and the expression level correlated with tumor grade and microvessel density in glioma specimens. Glioma patients with high VASN expression had a shorter overall survival time. Knockdown of VASN in glioma cells by shRNA significantly inhibited the malignancy of glioma, including cell proliferation, colony formation, invasion, and sphere formation. Ectopic expression of VASN increased glioma progression in vitro. The expression of VASN correlated with the mesenchymal type of glioblastoma multiforme (GBM) subtyped by gene set enrichment analysis (GSEA). Our results showed that the concentration of VASN was increased in the conditioned medium (CM) from glioma cells with VASN overexpression, and the CM from glioma cells with knockdown or overexpressed VASN inhibited or promoted HUVEC migration and tubulogenesis in vitro, respectively. Glioma growth and angiogenesis were stimulated upon ectopic expression of VASN in vivo. The STAT3 and NOTCH pathways were found to be activated and inhibited by VASN overexpression. Our findings suggest that VASN stimulates tumor progression and angiogenesis in glioma, and, as such, represents a novel therapeutic target for glioma.

Serum Homocysteine, VEGF and TGF-β1 dynamic change in colorectal cancer patients prior and post-operation

Background: The aim of the study was to evaluate the serum homocysteine (Hcy), vascular endothelial growth factor (VEGF) and transforming growth factor β1 (TGF-β1) dynamic change in colorectal cancer patients pre- and post-operation.

Material and methods: One hundred and eighteen CRC patients treated with surgery (CRC group) and 56 healthy controls (Control group) were included in this work. The serum Hcy, VEGF TGF-β1 were examined by enzymatic cycle and enzyme-linked immunosorbent assay (ELISA) of the two groups. We followed patients for 12 months and out of the 118 CRC patients, 14 patients had recurrent disease. Serum Hcy, VEGF and TGF-β1 were measured before and after surgery and repeated every 2 months.

Results Serum Hcy, VEGF and TGF-β1 were 16.20 ± 4.79 μmol/L, 492.36 ± 97.32 pg/ml, 29.23 ± 7.47 pg/ml for the CRC group and 8.98 ± 3.02 μmol/L, 315.21 ± 56.28 pg/ml, 7.69 ± 2.31 pg/ml for the control groups. Serum Hcy, VEGF and TGF-β1 was significantly (p<0.05) lower after surgery in both recurrent and nonrecurrent CRC patients (p<0.05). Interestingly, serum Hcy, VEGF and TGF-β1 gradually increased with time.

Conclusion Serum Hcy, VEGF and TGF-β1 levels are elevated in CRC patients and may correlated with the post-operative disease recurrence.

Sialic acid as a target for the development of novel antiangiogenic strategies

Sialic acid is associated with glycoproteins and gangliosides of eukaryotic cells. It regulates various molecular interactions, being implicated in inflammation and cancer, where its expression is regulated by sialyltransferases and sialidases. Angiogenesis, the formation of new capillaries, takes place during inflammation and cancer, and represents the outcome of several interactions occurring at the endothelial surface among angiogenic growth factors, inhibitors, receptors, gangliosides and cell-adhesion molecules. Here, we elaborate on the evidences that many structures involved in angiogenesis are sialylated and that their interactions depend on sialic acid with implications in angiogenesis itself, inflammation and cancer. We also discuss the possibility to exploit sialic acid as a target for the development of novel antiangiogenic drugs.