Thrombin cleavage of osteopontin initiates osteopontin's tumor-promoting activity

Small Integrin binding Ligand N-linked Glycoproteins, prostate-specific antigen and time to prostate cancer diagnosis

BACKGROUND

Small Integrin Binding Ligand N-linked Glycoproteins (SIBLINGs1) were associated with cancer in cross-sectional studies. Whether SIBLINGs associate with preclinical disease is unknown.

METHODS

A retrospective longitudinal case control study was performed to determine the association of SIBLINGs and prostate-specific antigen (PSA) with preclinical disease. Paired serum samples from 109 cancer-free Baltimore Longitudinal Study on Aging participants were divided into those that were either most distal or proximal to diagnosis (cases) or censored (controls). Dentin sialophosphoprotein (DSPP), bone sialoprotein (BSP), osteopontin (OPN), and PSA were measured by immunoassay and dichotomized into low or high based on their respective cut-off values. Associations of time to diagnosis or death, modeled as disease-free survival (DFS) or overall survival (OS), were assessed using Kaplan Meier and Cox proportional hazard survival estimates on individual and aggregated biomarkers in distal or proximal sets separately. Models were adjusted for relevant covariates. A false discovery rate analysis assessed significance of hazard ratios (HRs) in sets.

RESULTS

Biomarkers/aggregates identified as true discoveries for DFS included DSPP + PSA, OPN + PSA, DSPP + BSP + PSA, DSPP + OPN + PSA, where unadjusted distal HRs ranged between 11 and 27 and after adjusting for age from 7 to 15, while proximal HRs ranged between 6 and 10 unadjusted and 5 to 12 after adjusting for age. For proximal OS, true discoveries included DSPP + BSP, DSPP + OPN, DSPP + BSP + OPN, and DSPP + OPN + PSA where unadjusted HRs ranged between 6 and 20 while age-adjusted HRs ranged between 5 and 12.

CONCLUSIONS

These observations support SIBLINGs as biomarkers that associate with DFS and OS in prediagnosis samples.

Osteopontin as a potential mediator of inflammation in HIV and comorbid conditions

INTRODUCTION

Approximately 39 million people live with HIV globally, with 1.3 million new infections annually. Despite improved treatment, noncommunicable diseases (NCDs) such as cardiovascular disease (CVD), neurological disorders, chronic kidney disease (CKD), and cancer are now the leading causes of death among people with HIV (PWH). Osteopontin (OPN) has emerged as a notable mediator in the inflammatory response to HIV and related NCDs. Our aim is to review the current understanding of OPN's role in HIV-related inflammatory pathways to highlight potential therapeutic avenues for improved treatment and mitigation of comorbidities.

METHODS

We conducted a systematic review by searching relevant literature using specific keywords related to HIV, osteopontin, cardiovascular disease, inflammation, neurological disorders, cancer, and chronic kidney disease. The collected studies were organized and categorized by key themes, followed by a comprehensive analysis to identify patterns and draw conclusions regarding OPN's role in HIV-associated comorbidities.

RESULTS

The intricate interactions between OPN, its isoforms, and HIV-related illnesses suggest that OPN can exhibit both pro-inflammatory and anti-inflammatory roles, depending on the stage of the disease and the specific cell type involved. Its functions are diverse throughout the progression of HIV and its associated comorbidities, including CVD, CKD, cancer, and neurological disorders.

CONCLUSION

OPN's effects on the disease progression of HIV and related NCDs are highly variable due to its diverse functions. Therefore, further research is essential to fully understand its complex roles before considering OPN as a therapeutic target for HIV and its comorbidities.

The immune duality of osteopontin and its therapeutic implications for kidney transplantation

Osteopontin (OPN) is a multifunctional glycoprotein with various structural domains that enable it to perform diverse functions in both physiological and pathological states. This review comprehensively examines OPN from multiple perspectives, including its protein structure, interactions with receptors, interactions with immune cells, and roles in kidney diseases and transplantation. This review explores the immunological duality of OPN and its significance and value as a biomarker and therapeutic target in kidney transplantation. In cancer, OPN typically promotes tumor evasion by suppressing the immune system. Conversely, in immune-related kidney diseases, particularly kidney transplantation, OPN activates the immune system by enhancing the migration and activation of immune cells, thereby exacerbating kidney damage. This immunological duality may stem from different OPN splice variants and the exposure, after cleavage, of different structural domains, which play distinct biological roles in cellular interactions. Additionally, OPN has a significant biological impact posttransplantation and on chronic kidney disease and, highlighting its importance as a biomarker and potential therapeutic target. Future research should further explore the specific mechanisms of OPN in kidney transplantation to improve treatment strategies and enhance patient quality of life.

Towards an emerging role for anticoagulants in cancer therapy: a systematic review and meta-analysis

Background

Anticoagulants, renowned for their role in preventing blood clot formation, have captivated researchers' attention for the exploitation of their potential to inhibit cancer in pre-clinical models.

Objectives

To undertake a systematic review and meta-analysis of the effects of anticoagulants in murine cancer research models. Further, to present a reference tool for anticoagulant therapeutic modalities relating to future animal pre-clinical models of cancer and their translation into the clinic.

Methods

Four databases were utilized including Medline (Ovid), Embase (Ovid), Web of science, and Scopus databases. We included studies relating to any cancer conducted in murine models that assessed the effect of traditional anticoagulants (heparin and its derivatives and warfarin) and newer oral anticoagulants on cancer.

Results

A total of 6,158 articles were identified in an initial multi-database search. A total of 157 records were finally included for data extraction. Studies on heparin species and warfarin demonstrated statistically significant results in favour of tumour growth and metastasis inhibition.

Conclusion

Our findings constitute a valuable reference guide for the application of anticoagulants in cancer research and explore the promising utilization of non-anticoagulants heparin in preclinical cancer research.

Systematic Review Registration

PROSPERO [CRD42024555603].

Identification of diagnostic biomarkers and immune cell infiltration in tongue squamous cell carcinoma using bioinformatic approaches

OBJECTIVE

In this study, we employed a bioinformatics approach to identify diagnostic biomarkers for tongue squamous cell carcinoma (TSCC) and investigate the infiltration of immune cells in TSCC, as well as the relationship between biomarkers and immune cells.

METHODS

We obtained the TSCC expression dataset from a database and conducted differential gene expression analysis between TSCC and adjacent normal tissues using R software. Enrichment analysis of the differentially expressed genes (DEGs) was performed using the DAVID website. Protein interaction networks for the DEGs were constructed, and hub genes were identified using tools such as STRING and Cytoscape. Survival analysis was conducted to identify diagnostic biomarkers and the infiltration of immune cells in TSCC was analyzed using the inverse convolution algorithm with Cibersort software. Finally, the expression of the discovered molecules was verified through clinical pathological sections.

RESULTS

We identified 24 DEGs in TSCC, primarily associated with signal transduction, substance metabolism, innate immune response, and other related signaling pathways. Among the 24 hub genes screened through the construction of a protein-protein interaction (PPI) network, seven (MMP13, POSTN, MMP9, MMP10, MMP3, SPP1, MMP1) exhibited prognostic value. Survival analysis indicated that SPP1 demonstrated diagnostic potential. The expression level of the SPP1 gene showed a correlation with TSCC as well as several immune cell types, including macrophage M0, M1, M2, CD8+ T cell, activated NK cell, and monocyte (p < 0.05). Histological results confirmed higher expression of SPP1 in TSCC tissues compared to adjacent non-cancerous tissues, particularly in CD68-expressing macrophages.

CONCLUSION

Our findings suggest that SPP1 serves as a diagnostic biomarker for TSCC and is involved in immune cell infiltration within TSCC tissues. The correlation between SPP1 and macrophages may offer new insights for targeted therapeutic research on TSCC.

Regulating protein corona on nanovesicles by glycosylated polyhydroxy polymer modification for efficient drug delivery

The dynamic protein corona formed on nanocarriers has been revealed to strongly affect their in vivo behaviors. Precisely manipulating the formation of protein corona on nanocarriers may provide an alternative impetus for specific drug delivery. Herein, we explore the role of glycosylated polyhydroxy polymer-modified nanovesicles (CP-LVs) with different amino/hydroxyl ratios in protein corona formation and evolution. CP-LVs with an amino/hydroxyl ratio of approximately 0.4 (CP1-LVs) are found to efficiently suppress immunoglobulin adsorption in blood and livers, resulting in prolonged circulation. Moreover, CP1-LVs adsorb abundant tumor distinctive proteins, such as CD44 and osteopontin in tumor interstitial fluids, mediating selective tumor cell internalization. The proteins corona transformation specific to the environment appears to be affected by the electrostatic interaction between CP-LVs and proteins with diverse isoelectric points. Benefiting from surface modification-mediated protein corona regulation, paclitaxel-loaded CP1-LVs demonstrate superior antitumor efficacy to PEGylated liposomes. Our work offers a perspective on rational surface-design of nanocarriers to modulate the protein corona formation for efficient drug delivery.

Methods to Investigate Thrombin Cleavage of Osteopontin (OPN)

Osteopontin (OPN) is a matricellular protein containing binding sites for a variety of ligands including an RGD sequence for binding to αvβ3 integrins. OPN is a conserved substrate for thrombin, the effector protease of the coagulation cascade. Thrombin cleaves OPN at a single site revealing new functionalities such as a previously cryptic α4β1 and α9β1 integrin-binding site. That integrin-binding site is abolished upon treatment with a basic carboxypeptidase. The thrombin cleavage of OPN has been demonstrated to play a role in regulating tumor growth.This report describes methods for production of full-length OPN as well as the enzymatically cleaved OPN fragments resulting from thrombin and carboxypeptidase treatments. Quantification procedures for the various OPN proteins are described as well as functional assays on mouse melanoma and myeloid cell lines.

Preliminary Study of the Relationship between Osteopontin and Relapsed Hodgkin's Lymphoma

The primary objective of this study was to investigate the potential role of tissue osteopontin, also known as secreted phosphoprotein 1 (SPP1), as a contributing factor to an unfavorable prognosis in classical Hodgkin's lymphoma (HL) patients who received the same treatment protocol. The study involved 44 patients aged 4-22 years, with a median follow-up period of 3 years. Patients with higher levels of SPP1 were associated with tissue necrosis and inflammation, and there was a trend toward a poorer prognosis in this group. Before therapy, we found a correlation between positron emission tomography (PET) scans and logarithmic SPP1 levels (p = 0.035). However, the addition of SPP1 levels did not significantly enhance the predictive capacity of PET scans for recurrence or progression. Elevated SPP levels were associated with tissue mRNA counts of chemotactic and inflammatory chemokines, as well as specific monocyte/dendritic cell subtypes, defined by IL-17RB, PLAUR, CXCL8, CD1A, CCL13, TREM1, and CCL24 markers. These findings contribute to a better understanding of the potential factors influencing the prognosis of HL patients and the potential role of SPP1 in the disease. While the predictive accuracy of PET scans did not substantially improve during the study, the results underscore the complexity of HL and highlight the relationships between SPP1 and other factors in the context of HL relapse.

Luteolin as a potential hepatoprotective drug: Molecular mechanisms and treatment strategies

Luteolin is a flavonoid widely present in various traditional Chinese medicines. In recent years, luteolin has received more attention due to its impressive liver protective effect, such as metabolic associated fatty liver disease, hepatic fibrosis and hepatoma. This article summarizes the pharmacological effects, pharmacokinetic characteristics, and toxicity of luteolin against liver diseases, and provides prospect. The results indicate that luteolin improves liver lesions through various mechanisms, including inhibiting inflammatory factors, reducing oxidative stress, regulating lipid balance, slowing down excessive aggregation of extracellular matrix, inducing apoptosis and autophagy of liver cancer cells. Pharmacokinetics research manifested that due to metabolic effects, the bioavailability of luteolin is relatively low. It is worth noting that appropriate modification, new delivery systems, and derivatives can enhance its bioavailability. Although many studies have shown that the toxicity of luteolin is minimal, strict toxicity experiments are still needed to evaluate its safety and promote its reasonable development. In addition, this study also discussed the clinical applications related to luteolin, indicating that it is a key component of commonly used liver protective drugs in clinical practice. In view of its excellent pharmacological effects, luteolin is expected to become a potential drug for the treatment of various liver diseases.

Thrombin Cleavage of Osteopontin and the Host Anti-Tumor Immune Response

Osteopontin (OPN) is a multi-functional protein that is involved in various cellular processes such as cell adhesion, migration, and signaling. There is a single conserved thrombin cleavage site in OPN that, when cleaved, yields two fragments with different properties from full-length OPN. In cancer, OPN has tumor-promoting activity and plays a role in tumor growth and metastasis. High levels of OPN expression in cancer cells and tumor tissue are found in various types of cancer, including breast, lung, prostate, ovarian, colorectal, and pancreatic cancer, and are associated with poor prognosis and decreased survival rates. OPN promotes tumor progression and invasion by stimulating cell proliferation and angiogenesis and also facilitates the metastasis of cancer cells to other parts of the body by promoting cell adhesion and migration. Furthermore, OPN contributes to immune evasion by inhibiting the activity of immune cells. Thrombin cleavage of OPN initiates OPN's tumor-promoting activity, and thrombin cleavage fragments of OPN down-regulate the host immune anti-tumor response.

Mechanistic Insights into the Role of OPN in Mediating Brain Damage via Triggering Lysosomal Damage in Microglia/Macrophage

We previously found that osteopontin (OPN) played a role in hypoxia–ischemia (HI) brain damage. However, its underlying mechanism is still unknown. Bioinformatics analysis revealed that the OPN protein was linked to the lysosomal cathepsin B (CTSB) and galectin-3 (GAL-3) proteins after HI exposure. In the present study, we tested the hypothesis that OPN was able to play a critical role in the lysosomal damage of microglia/macrophages following HI insult in neonatal mice. The results showed that OPN expression was enhanced, especially in microglia/macrophages, and colocalized with lysosomal-associated membrane protein 1 (LAMP1) and GAL-3; this was accompanied by increased LAMP1 and GAL-3 expression, CTSB leakage, as well as impairment of autophagic flux in the early stage of the HI process. In addition, the knockdown of OPN expression markedly restored lysosomal function with significant improvements in the autophagic flux after HI insult. Interestingly, cleavage of OPN was observed in the ipsilateral cortex following HI. The wild-type OPN and C-terminal OPN (Leu152-Asn294), rather than N-terminal OPN (Met1-Gly151), interacted with GAL-3 to induce lysosomal damage. Furthermore, the secreted OPN stimulated lysosomal damage by binding to CD44 in microglia in vitro. Collectively, this study demonstrated that upregulated OPN in microglia/macrophages and its cleavage product was able to interact with GAL-3, and secreted OPN combined with CD44, leading to lysosomal damage and exacerbating autophagosome accumulation after HI exposure.

The Intracellular and Secreted Sides of Osteopontin and Their Putative Physiopathological Roles

Classically, osteopontin (OPN) has been described as a secreted glycophosprotein. Indeed, most data concerning its physiological and pathological roles are mainly related to the secreted OPN (sOPN). However, there are several instances in which intracellular OPN (iOPN) has been described, presenting some specific roles in distinct experimental models, such as in the immune system, cancer cells, and neurological disorders. We herein aimed to highlight and discuss some of these secreted and intracellular roles of OPN and their putative clinical and biological impacts. Moreover, by consolidating data from the OPN protein database, we also analyzed the occurrence of signal peptide (SP) sequences and putative subcellular localization, especially concerning currently known OPN splicing variants (OPN-SV). Comprehending the roles of OPN in its distinct cellular and tissue environments may provide data regarding the additional applications of this protein as biomarkers and targets for therapeutic purposes, besides further describing its pleiotropic roles.

The Role of Osteopontin in Tumor Progression Through Tumor-Associated Macrophages

Osteopontin (OPN) is a multifunctional phosphorylated protein. It is widely involved in solid tumor progression, such as intensification of macrophage recruitment, inhibition of T-cell activity, aggravation of tumor interstitial fibrosis, promotion of tumor metastasis, chemotherapy resistance, and angiogenesis. Most of these pathologies are affected by tumor-associated macrophages (TAMs), an important component of the tumor microenvironment (TME). TAMs have been extensively characterized, including their subsets, phenotypes, activation status, and functions, and are considered a promising therapeutic target for cancer treatment. This review focuses on the interaction between OPN and TAMs in mediating tumor progression. We discuss the strategies for targeting OPN and TAMs to treat cancer and factors that may affect the therapeutic outcomes of blocking OPN or depleting TAMs. We also discuss the role of cancer cell- vs. TAM-derived OPN in tumorigenesis, the mechanisms of how OPN affects TAM recruitment and polarization, and why OPN could mediate anti-tumor and pro-tumor effects, as well as previously reported discrepancies.

Effect of Thrombin on the Metabolism and Function of Murine Macrophages

Macrophages are plastic and heterogeneous immune cells that adapt pro- or anti-inflammatory phenotypes upon exposure to different stimuli. Even though there has been evidence supporting a crosstalk between coagulation and innate immunity, the way in which protein components of the hemostasis pathway influence macrophages remains unclear. We investigated the effect of thrombin on macrophage polarization. On the basis of gene expression and cytokine secretion, our results suggest that polarization with thrombin induces an anti-inflammatory, M2-like phenotype. In functional studies, thrombin polarization promoted oxLDL phagocytosis by macrophages, and conditioned medium from the same cells increased endothelial cell proliferation. There were, however, clear differences between the classical M2a polarization and the effects of thrombin on gene expression. Finally, the deletion and inactivation of secreted modular Ca²⁺-binding protein 1 (SMOC1) attenuated phagocytosis by thrombin-stimulated macrophages, a phenomenon revered by the addition of recombinant SMOC1. Manipulation of SMOC1 levels also had a pronounced impact on the expression of TGF-β-signaling-related genes. Taken together, our results show that thrombin induces an anti-inflammatory macrophage phenotype with similarities as well as differences to the classical alternatively activated M2 polarization states, highlighting the importance of tissue levels of SMOC1 in modifying thrombin-induced macrophage polarization.