Thrombospondin-2 as a Predictive Biomarker for Hepatocellular Carcinoma after Hepatitis C Virus Elimination by Direct-Acting Antiviral

We evaluated the value of secreted glycoprotein thrombospondin-2 (TSP-2) to predict hepatocellular carcinoma (HCC) occurrence in chronic hepatitis C (CHC) patients after Hepatitis C virus (HCV) elimination by direct-acting antiviral agents (DAAs). A total of 786 CHC patients without an HCC history who achieved a sustained virological response (SVR) with DAAs were randomly assigned 2:1, with 524 patients as the derivation cohort and 262 patients as the validation cohort. Serum TSP-2 levels at the end of treatment were measured by enzyme-linked immunosorbent assay (ELISA). In the derivation cohort, the cumulative HCC rate was significantly higher in the high TSP-2 group than in the low TSP-2 group. Multivariate Cox proportional hazards analysis revealed that TSP-2, α-fetoprotein (AFP), and the fibrosis-4 (FIB-4) index were independent HCC risk factors. The area under the receiver operating characteristic curve (AUROC) of the score calculated from these three factors (AFT score) for predicting HCC was 0.83, which was significantly higher than that of each factor alone (TSP-2: 0.70, AFP: 0.72, FIB-4: 0.69). The AFT score was used to stratify patients according to the risk of HCC occurrence in the validation cohort. Lastly, in patients with a FIB-4 index < 3.25, the serum TSP-2 levels could be used to identify those patients with a high risk of HCC occurrence. Serum TSP-2 levels are a predictive biomarker of HCC occurrence in CHC patients after HCV elimination by DAA treatment. The AFT score using TSP-2, AFP, and the FIB-4 index may identify those who require HCC surveillance.

Thrombospondin-2 stimulates MMP-9 production and promotes osteosarcoma metastasis via the PLC, PKC, c-Src and NF-κB activation

Osteosarcoma is an extremely common primary bone malignancy that is highly metastatic, with most deaths resulting from pulmonary metastases. The extracellular matrix protein thrombospondin‐2 (TSP‐2) is key to many biological processes, such as inflammation, wound repair and tissue remodelling. However, it is unclear as to what biological role TSP‐2 plays in human metastatic osteosarcoma. The immunochemistry analysis from osteosarcoma specimens identified marked up‐regulation of TSP‐2 in late‐stage osteosarcoma. Furthermore, we found that TSP‐2 increased the levels of matrix metallopeptidase 9 (MMP‐9) expression and thereby increased the migratory potential of human osteosarcoma cells. Osteosarcoma cells pre‐treated with an MMP‐9 monoclonal antibody (mAb), an MMP‐9 inhibitor, or transfected with MMP‐9 small interfering RNA (siRNA) reduced the capacity of TSP‐2 to potentiate cell migration. TSP‐2 treatment activated the PLCβ, PKCα, c‐Src and nuclear kappa factor B (NF‐κB) signalling pathways, while the specific siRNA, inhibitors and mutants of these cascades reduced TSP‐2‐induced stimulation of migration activity. Knockdown of TSP‐2 expression markedly reduced cell metastasis in cellular and animal experiments. It appears that an interaction between TSP‐2 and integrin αvβ3 activates the PLCβ, PKCα and c‐Src signalling pathways and subsequently activates NF‐κB signalling, increasing MMP‐9 expression and stimulating migratory activity amongst human osteosarcoma cells.

Thrombospondins in bone remodeling and metastatic bone disease

Thrombospondins (TSPs) are a family of five multimeric matricellular proteins. Through a wide range of interactions, TSPs play pleiotropic roles in embryogenesis and in tissue remodeling in adult physiology as well as in pathological conditions, including cancer development and metastasis. TSPs are active in bone remodeling, the process of bone resorption (osteolysis) and deposition (osteogenesis) that maintains bone homeostasis. TSPs are particularly involved in aberrant bone remodeling, including osteolytic and osteoblastic skeletal cancer metastasis, frequent in advanced cancers such as breast and prostate carcinoma. TSPs are major players in the bone metastasis microenvironment, where they finely tune the cross talk between tumor cells and bone resident cells in the metastatic niche. Each TSP family member has different effects on the differentiation and activity of bone cells-including the bone-degrading osteoclasts and the bone-forming osteoblasts-with different outcomes on the development and growth of osteolytic and osteoblastic metastases. Here, we overview the involvement of TSP family members in the bone tissue microenvironment, focusing on their activity on osteoclasts and osteoblasts in bone remodeling, and present the evidence to date of their roles in bone metastasis establishment and growth.

Thrombospondin 2 promotes tumor metastasis by inducing matrix metalloproteinase-13 production in lung cancer cells

Thrombospondin (TSP)-2, a matricellular glycoprotein of the TSP family, regulates multiple biological functions, including proliferation, angiogenesis, cell adhesion, and extracellular matrix (ECM) modeling. The clinical relevance of TSP-2 has been explored in many different cancers. TSP-2 expression levels vary between different cancer types, and their role in tumor progression remains controversial. Although previous studies have reported higher serum TSP-2 levels in patients with non-small cell lung cancer, the role of TSP-2 in lung cancer progression remains to be addressed. A total of 585 lung adenocarcinoma datasets, including mRNA sequencing and clinical data, were retrieved from The Cancer Genome Atlas (TCGA). Forty paired adjacent normal tissues and lung tumor tissue datasets were used to examine TSP-2 expression levels. Tumor microarray were performed with immunohistochemical staining to examine TSP-2 expression in lung cancer patients. Transwell migration assay, quantitative real-time PCR and Western blot were used to investigate molecular mechanism of TSP-2 in lung cancer cell. TSP-2 promotes matrix metalloproteinase-13 (MMP-13) expression, cell migration, and cell invasion by mediating integrin αvβ3/FAK/Akt/NF-κB signal transduction. Using TSP-2 knockdown stable cell lines, we found that TSP-2 knockdown reduces MMP-13 expression and cell mobility. When we manipulated the tumor tissue microarray and TCGA datasets to investigate the clinical relevance of TSP-2, we found high TSP-2 expression levels in lung cancer specimens. The present study demonstrates that TSP-2 regulates cell mobility through MMP-13 expression in lung cancer cells. In addition, TSP-2 expression was associated with MMP-13 expression and poor prognosis in lung cancer. TSP-2 may therefore be a promising novel target for lung cancer treatment.

Therapeutic Role for TSP-2 Antibody in a Murine Asthma Model

BACKGROUND

Specific immunotherapy, including agonists for Toll-like receptor 2 (TLR2), have been shown to protect from allergies and to have a high immunomodulatory capacity.

METHODS

A new antibody, TSP-2, reactive against an epitope of the extracellular domain of TLR2, was identified. The effect of the antibody on dendritic cells was assessed by immunohistochemistry, Western blot, and flow cytometric analysis. The effect of TSP-2 in a murine asthma model induced with ovalbumin (OVA) was assessed. The model is a form of airway hyperresponsiveness (AHR) and was analyzed by whole-body plethysmography, the measurement of Th1/Th2 cytokines in bronchial alveolar lavage fluid (BALF) and serum by ELISA, and the CCK-8 assay for lymphocyte proliferation. The effect of TSP-2 on the maturation of bone marrow-derived dendritic cells (BMDCs) was assessed by flow cytometric analysis.

RESULTS

TSP-2 promoted the maturation of dendritic cells and the proliferation of lymphocyte in vitro and in vivo. The effect of TSP-2 on T helper 1 (Th1)/Th2 cytokine secretion was slightly more powerful than that of Pam3CSK4. TSP-2 antibody reduced AHR and OVA-specific IgE levels in allergic asthma. TSP-2 antibody also reduced lung inflammation and decreased leukocyte numbers in an OVA-sensitized and challenged asthma model. TSP-2 antibody increased OVA-stimulated I-A, CD80, CD86, and MHC-II levels on BMDCs.

CONCLUSIONS

This study identifies a novel therapeutic strategy for AHR, which uses antibodies reactive against TLR2. It also provides theoretical evidence for the control of allergic asthma by targeting TLR2.

A multivalent chimeric vaccine composed of Schistosoma mansoni SmTSP-2 and Sm29 was able to induce protection against infection in mice

Schistosoma mansoni is a blood fluke parasite responsible for schistosomiasis. The best long-term strategy to control schistosomiasis is through immunization combined with drug treatment. In this study, we cloned, expressed and purified SmTSP-2 fused to the N- and C-terminal halves of Sm29 and tested these chimeras as vaccine candidates using an adjuvant approved to be used in humans. The results demonstrated that vaccination with SmTSP-2 fused to N- or C-terminus of Sm29-induced reduction in worm burden and liver pathology when compared to control animals. Additionally, we detected high levels of mouse-specific IgG, IgG1 and IgG2a against both chimeras and significant amounts of IFN-γ and TNF-α and no IL-4. Finally, studies with sera from patients resistant to infection and living in schistosomiasis endemic areas revealed high levels of specific IgG to both chimeras when compared to healthy individuals. In conclusion, SmTSP-2/Sm29 chimeras tested here induced partial protection against infection and might be a potential vaccine candidate.