Alterations of insulin-like growth factor binding protein 3 (IGFBP-3) glycosylation in patients with breast tumours

The Role of Glycosyltransferases in Colorectal Cancer

Colorectal cancer (CRC) is one of the main causes of cancer death in the world. Post-translational modifications (PTMs) have been extensively studied in malignancies due to its relevance in tumor pathogenesis and therapy. This review is focused on the dysregulation of glycosyltransferase expression in CRC and its impact in cell function and in several biological pathways associated with CRC pathogenesis, prognosis and therapeutic approaches. Glycan structures act as interface molecules between cells and their environment and in several cases facilitate molecule function. CRC tissue shows alterations in glycan structures decorating molecules, such as annexin-1, mucins, heat shock protein 90 (Hsp90), β1 integrin, carcinoembryonic antigen (CEA), epidermal growth factor receptor (EGFR), insulin-like growth factor-binding protein 3 (IGFBP3), transforming growth factor beta (TGF-β) receptors, Fas (CD95), PD-L1, decorin, sorbin and SH3 domain-containing protein 1 (SORBS1), CD147 and glycosphingolipids. All of these are described as key molecules in oncogenesis and metastasis. Therefore, glycosylation in CRC can affect cell migration, cell–cell adhesion, actin polymerization, mitosis, cell membrane repair, apoptosis, cell differentiation, stemness regulation, intestinal mucosal barrier integrity, immune system regulation, T cell polarization and gut microbiota composition; all such functions are associated with the prognosis and evolution of the disease. According to these findings, multiple strategies have been evaluated to alter oligosaccharide processing and to modify glycoconjugate structures in order to control CRC progression and prevent metastasis. Additionally, immunotherapy approaches have contemplated the use of neo-antigens, generated by altered glycosylation, as targets for tumor-specific T cells or engineered CAR (Chimeric antigen receptors) T cells.

Effects of insulin-like growth factor binding protein 3 on apoptosis of cutaneous squamous cell carcinoma cells

Background

Cutaneous squamous cell carcinoma (CSCC) is the second most common carcinoma worldwide. Clinical treatment for patients with CSCC remains non-ideal. Insulin-like growth factor binding protein 3 (IGFBP3), a member of the insulin-like growth (IGF) system, participates in several biological processes, including cellular proliferation and apoptosis. Here, we explored the functional role of IGFBP3 in apoptosis and proliferation of A431 cells, a human CSCC cell line.

Materials and methods

Differential expression analysis, immunohistochemistry, immunoblotting, TUNEL assay, and CCK8 assay techniques were used to investigate the IGFBP3 expression levels in both A431 cells and CSCC tissue surgically obtained from humans as well as to explore the functional role of IGFBP3 in the apoptosis and proliferation of A431 cells.

Results

By using normal epidermal keratinocytes for comparison, we identified the top 10 ranked differentially upregulated genes expressed in human cutaneous squamous cell carcinoma cell lines. Among these 10 genes, IGFBP3 was ranked number 1. By using immunohistochemistry, we found that the expression level of IGFBP3 was significantly elevated in CSCC tissue compared with that in normal human skin tissue. Knockdown of IGFBP3 in A431 cells by transfection with IGFBP3-specific siRNA markedly altered the expression of proteins that contribute to apoptosis via mitochondrial pathways, significantly suppressing the expression of Bax and active caspase-3, while significantly increasing B-cell lymphoma-2 expression. TUNEL assay confirmed the effect of knockdown of IGFBP3 on the apoptosis as well. In addition, knockdown of IGFBP3 inhibited the proliferation of A431 cells.

Conclusion

IGFBP3 is overexpressed in both CSCC cell lines and tissue. Knockdown of IGFBP3 enhanced the apoptosis via a mitochondrial pathway and inhibited the proliferation of A431 cells. These findings indicate that IGFBP3 may be a biomarker and a potential therapeutic target for CSCC.

Glycoprotein biomarkers for the detection of pancreatic ductal adenocarcinoma

Pancreatic cancer (PaC) shows a clear tendency to increase in the next years and therefore represents an important health and social challenge. Currently, there is an important need to find biomarkers for PaC early detection because the existing ones are not useful for that purpose. Recent studies have indicated that there is a large window of time for PaC early detection, which opens the possibility to find early biomarkers that could greatly improve the dismal prognosis of this tumor. The present manuscript reviews the state of the art of the existing PaC biomarkers. It focuses on the anomalous glycosylation process and its role in PaC. Glycan structures of glycoconjugates such as glycoproteins are modified in tumors and these modifications can be detected in biological fluids of the cancer patients. Several studies have found serum glycoproteins with altered glycan chains in PaC patients, but they have not shown enough specificity for PaC. To find more specific cancer glycoproteins we propose to analyze the glycan moieties of a battery of glycoproteins that have been reported to increase in PaC tissues and that can also be found in serum. The combination of these new candidate glycoproteins with their aberrant glycosylation together with the existing biomarkers could result in a panel, which would expect to give better results as a new tool for early diagnosis of PaC and to monitor the disease.

DNA-PK phosphorylation of IGFBP-3 is required to prevent apoptosis in retinal endothelial cells cultured in high glucose

PURPOSE

The goal of this study was to determine whether Compound 49b stimulates insulin-like growth factor binding protein-3 (IGFBP-3) activation in retinal endothelial cells (REC) through DNA-dependent protein kinase (DNA-PK).

METHODS

REC were grown in a normal glucose (5 mM) or high glucose medium (25 mM). Some cells were transfected with protein kinase A (PKA) siRNA, following treatment with 50 nM Compound 49b, a novel β-adrenergic receptor agonist. Cell proteins were extracted and analyzed for DNA-PK expression by Western blotting. Additional cells were treated with or without NU7441 (a specific DNA-PK inhibitor) prior to Compound 49b treatment. Cell lysates were processed for IGFBP-3 ELISA analyses and Western blotting to measure casein kinase 2 (CK2). Immunoprecipitation for total and phospho-IGFBP-3, cell proliferation and cell death measurements were done after transfection with the S(156)A IGFBP-3 mutation (key phosphorylation site involved in DNA-PK) plasmid DNA.

RESULTS

Compound 49b required DNA-PK to activate IGFBP-3 in REC. IGFBP-3 activation was significantly reduced following treatment with either the DNA-PK inhibitor or following transfection with the IGFBP-3 S(156)A mutant plasmid (P < 0.05). Significant increases in cell death and decreases in cell proliferation were also observed in cells transfected with the IGFBP-3 S(156)A mutant plasmid (P < 0.05). Casein kinase levels were not altered after treatment with NU7741 or Compound 49b.

CONCLUSIONS

Our findings suggest Compound 49b induces DNA-PK levels through PKA activity. DNA-PK is required for Compound 49b-induced IGFBP-3 expression, leading to inhibition of REC cell death.

Lectin chromatography/mass spectrometry discovery workflow identifies putative biomarkers of aggressive breast cancers

We used a lectin chromatography/MS-based approach to screen conditioned medium from a panel of luminal (less aggressive) and triple negative (more aggressive) breast cancer cell lines (n=5/subtype). The samples were fractionated using the lectins Aleuria aurantia (AAL) and Sambucus nigra agglutinin (SNA), which recognize fucose and sialic acid, respectively. The bound fractions were enzymatically N-deglycosylated and analyzed by LC-MS/MS. In total, we identified 533 glycoproteins, ∼90% of which were components of the cell surface or extracellular matrix. We observed 1011 glycosites, 100 of which were solely detected in ≥3 triple negative lines. Statistical analyses suggested that a number of these glycosites were triple negative-specific and thus potential biomarkers for this tumor subtype. An analysis of RNaseq data revealed that approximately half of the mRNAs encoding the protein scaffolds that carried potential biomarker glycosites were up-regulated in triple negative vs luminal cell lines, and that a number of genes encoding fucosyl- or sialyltransferases were differentially expressed between the two subtypes, suggesting that alterations in glycosylation may also drive candidate identification. Notably, the glycoproteins from which these putative biomarker candidates were derived are involved in cancer-related processes. Thus, they may represent novel therapeutic targets for this aggressive tumor subtype.

Relationship of insulin-like growth factor (IGF) binding protein-3 (IGFBP-3) gene polymorphism with the susceptibility to development of prostate cancer and influence on serum levels of IGF-I, and IGFBP-3

The bioavailability of IGF-I is controlled by the binding protein, IGF binding protein-3 (IGFBP-3). In addition, IGFBP-3 is a strong anti-proliferative protein that provokes apoptosis and inhibits cell proliferation in prostate cancer. We conducted this study to investigate the association between IGFBP-3 gene polymorphism and serum levels of IGF-I and IGFBP-3 and the incidence of prostate cancer (PCa) and benign prostatic hyperplasia (BPH). DNA isolation was performed in peripheral blood samples obtained from all participants. Required areas were amplified with polymerase chain reaction restriction fragment length polymorphism (PCR-RLFP) technique by using proper primers belonging to this gene area. We also measured serum IGF-I and IGFBP-3 levels. The IGFBP-3 -202 A/C polymorphism genotype frequencies showed a significant difference between PCa patients and controls (χ(2)=6.27, df=2.0, P=0.026), as well as between BPH patients and controls (χ(2)=11.57, df=4.0, P=0.014). The AA genotype frequency was significantly decreased in PCa and BPH patients compared to control group and the risk of PCa and BPH occurrence of this genotype was decreased accordingly (PCa; OR=0.28, 95% CI=0.17-0.44, P=0.0001; BPH: OR=0.48, 95% CI=0.29-0.77, P=0.001). Age-adjusted mean serum IGFBP-3 concentrations were highest in the individuals with the AA genotype and diminished significantly in a stepwise manner in the presence of 1 or 2 copies of the C allele (4577 ng/ml, 3929 ng/ml and 3349 ng/ml, respectively). Patients with PCa and BPH had lower serum IGF-1 (P=0.001, and P=0.01, respectively) and IGFBP-3 levels (P=0.001, and P=0.01, respectively) compared with controls. The AA genotype at IGFBP-3 gene polymorphism is associated with reduced risks of PCa and BPH. Both IGF-I and IGFBP-3 concentrations, are associated with modified risks of PCa and BPH.

Insulin-like growth factor binding protein-3 (IGFBP-3) gene variants are associated with renal cell carcinoma

OBJECTIVE

• To evaluate the A to C nucleotide change located 202 bp upstream to the transcription start site, (-202 A/C polymorphism), in the insulin-like growth factor (IGF) binding protein-3 (IGFBP-3) gene, and its association with renal carinogenesis and with clinicopathological characteristics.

PATIENTS AND METHODS

• We matched 158 male patients with clear-cell renal cell carcinoma (CCRCC) to 316 healthy controls, and genotyped one single nucleotide polymorphism (rs2854744) using the polymerase chain reaction restriction fragment length polymorphism technique.

RESULTS

• The alleles and genotypes differed significantly between patients with CCRCC and controls (patients with CCRCC, P= 0.82; controls, P= 0.88). • We found that the frequency of the AA genotype was significantly higher in patients with CCRCC than in controls (odds ratio [OR]= 4.62, 95% confidence interval [CI]= 3.41-7.42, P= 0.001). • The A allele had a gene dose effect in increasing the risk of CCRCC (OR = 4.75, 95% CI = 3.64-7.64, P= 0.001). • The distribution of IGFBP-3 genotypes was also significantly associated with the histological grade (P= 0.001) and clinical stage (P= 0.001).

CONCLUSION

• In the Iranian population, the polymorphism of the IGFBP-3 gene plays a pivotal role in the development of CCRCC.