Hye-Nam Son

Transforming growth factor-β-induced protein (TGFBIp/β ig-h3) activates platelets and promotes thrombogenesis

Transforming growth factor-beta-induced protein (TGFBIp)/beta ig-h3 is a 68-kDa extracellular matrix protein that is functionally associated with the adhesion, migration, proliferation, and differentiation of various cells. The presence of TGFBIp in platelets led us to study the role of this protein in the regulation of platelet functions. Upon activation, platelet TGFBIp was released and associated with the platelets. TGFBIp mediates not only the adhesion and spread of platelets but also activates them, resulting in phosphatidylserine exposure, alpha-granule secretion, and increased integrin affinity. The fasciclin 1 domains of TGFBIp are mainly responsible for the activation of platelets. TGFBIp promotes thrombus formation on type I fibrillar collagen under flow conditions in vitro and induces pulmonary embolism in mice. Moreover, transgenic mice, which have approximately a 1.7-fold greater blood TGFBIp concentration, are significantly more susceptible to collagen- and epinephrine-induced pulmonary embolism than wild-type mice. These results suggest that TGFBIp, a human platelet protein, plays important roles in platelet activation and thrombus formation. Our findings will increase our understanding of the novel mechanism of platelet activation, contributing to a better understanding of thrombotic pathways and the development of new antithrombotic therapies.

Multiple FAS1 domains and the RGD motif of TGFBI act cooperatively to bind αvβ3 integrin, leading to anti-angiogenic and anti-tumor effects

TGFBI, a transforming growth factor β-induced extracellular matrix protein, circulates at a level of ~300ng/ml in humans and modulates several integrin-mediated cellular functions. The protein contains an N-terminal EMI domain, four consecutive FAS1 domains, and the RGD motif. Each FAS1 domain and the RGD motif have been known to interact with avb3 integrin. Here, we found that the binding affinity (Kd) of TGFBI for αvβ3 integrin was approximately 3.8×10(-8)M, a value ~2300-fold higher than that of a single FAS1 domain, and demonstrated that this greater affinity was due to the cooperative action of the four FAS1 domains and the RGD motif. Moreover, TGFBI exhibited more potent anti-angiogenic and anti-tumorigenic activities, even at a 100-fold lower molar dose than the reported effective dose of the FAS1 domain. Finally, our data showed that TGFBI specifically targeted the tumor vasculature and accumulated at the tumor site. Collectively, our results support the theory that TGFBI acts as a potent endogenous anti-tumor and anti-angiogenic molecule by targeting αvβ3 integrin, and highlights the importance of physiological circulating TGFBI levels in inhibiting tumor growth.

Anti‐transforming growth factor β‐induced protein antibody ameliorates vascular barrier dysfunction and improves survival in sepsis

Sepsis is a systemic inflammatory response syndrome resulting from a microbial infection. Transforming growth factor β‐induced protein (TGFBIp) is an extracellular matrix protein expressed by human endothelial cells and platelets that induces sepsis through interaction with integrin αvβ5. The aim of this study was to investigate the role of TGFBIp in vascular permeability and the underlying mechanisms using TGFBIp‐neutralizing antibody.

Decursin from Angelica gigas Nakai Inhibits B16F10 Melanoma Growth Through Induction of Apoptosis.

Decursin, a bioactive phytochemical isolated from Angelica gigas Nakai (danggwi), has shown preclinical anticancer efficacy in various cancer models. However, the antitumor effect of decursin in melanoma models remains undefined. The antitumor activities of decursin were investigated in B16F10 cells in vitro and in vivo. In this study, we show that treatment with decursin inhibited cell proliferation in a dose-dependent manner in B16F10 cells, but not in normal cells. Decursin also induced apoptosis in B16F10 cells, as determined by annexin V-staining assay and transferase-mediated nick-end labeling (TUNEL) staining assay. Decursin increased the phosphorylation of p38 as well as the expression of Bax while decreasing the phosphorylation of extracellular signaling-regulated kinase (ERK) and the expression of Bcl-2 in B16F10 cells. Moreover, decursin activated caspase-3 in B16F10 cells and xenograft tumor tissue. Together, these findings support further investigations into the potential use of decursin in the treatment of melanoma cells.

FAS1-domain protein inhibits VEGF165-induced angiogenesis by targeting the interaction between VEGFR-2 and αvβ3 integrin

It is known that VEGF receptors (VEGFR) and integrins interact with each other to regulate angiogenesis. We reported previously that the fasciclin 1 (FAS1) domain–containing protein, TGFBIp/βig-h3 (TGF-β–induced protein) is an angiogenesis regulator that inhibits both endothelial cell migration and growth via αvβ3 integrin. In an attempt to target the interaction between VEGFR-2 and αvβ3 integrin, we determined whether the FAS1 domain region of TGFBIp/βig-h3 (FAS1 domain protein) can block the interaction between the two receptors, leading to the suppression of angiogenesis. In this study, we showed that FAS1 domain protein inhibits VEGF165-induced endothelial cell proliferation and migration via αvβ3 integrin, resulting in the inhibition of VEGF165-induced angiogenesis. We also defined a molecular mechanism by which FAS1 domain protein blocks the association between αvβ3 integrin and VEGFR-2, showing that it binds to αvβ3 integrin but not to VEGFR-2. Blocking the association of these major angiogenic receptors with FAS1 domain protein inhibits signaling pathways downstream of VEGFR-2. Collectively, our results indicate that FAS1 domain protein, in addition to its inhibitory effect on αvβ3 integrin–mediated angiogenesis, also inhibits VEGF165-induced angiogenesis. Thus, FAS1 domain protein can be further developed into a potent anticancer drug that targets two principal angiogenic pathways. Mol Cancer Res; 10(8); 1010–20. ©2012 AACR.

Advantages of the Phosphatidylserine-Recognizing Peptide PSP1 for Molecular Imaging of Tumor Apoptosis Compared with Annexin V

A number of peptide-based indicators have been identified and reported as potential apoptosis probes, offering great promise for early assessment of therapeutic efficacy in several types of cancer. Direct comparison of the newly developed probes with previously used ones would be an important step in assessing possible applications. Here, we compared the newly identified peptide-based phosphatidylserine (PS) indicator PSP1 (CLSYYPSYC) with annexin V, a common probe for molecular imaging of apoptotic cells, with respect to PS binding kinetics, apoptotic cell-targeting ability, and the efficacy of homing to apoptotic tumor cells in a mouse model after treatment with the anticancer agent camptothecin. Our results indicate that PSP1 efficiently targeted apoptotic cells and generated apoptosis/tumor-specific signals after cancer treatment in the animal model, whereas a similar dose of annexin V showed weak signals. The formation of a stable complex of PSP1 with PS might be one reason for the efficient in vivo targeting. We suggest that PSP1 has potential advantages for in vivo apoptotic cell imaging and could serve as a platform for the development of de novo peptide-based probes for apoptosis.

Design of a Multicomponent Peptide-Woven Nanocomplex for Delivery of siRNA

We developed and tested a multicomponent peptide-woven siRNA nanocomplex (PwSN) comprising different peptides designed for efficient cellular targeting, endosomal escape, and release of siRNA. To enhance tumor-specific cellular uptake, we connected an interleukin-4 receptor-targeting peptide (I4R) to a nine-arginine peptide (9r), yielding I4R-9r. To facilitate endosomal escape, we blended endosomolytic peptides into the I4R-9r to form a multicomponent nanocomplex. Lastly, we modified 9r peptides by varying the number and positions of positive charges to obtain efficient release of siRNA from the nanocomplex in the cytosol. Using this step-wise approach for overcoming the biological challenges of siRNA delivery, we obtained an optimized PwSN with significant biological activity in vitro and in vivo. Interestingly, surface plasmon resonance analyses and three-dimensional peptide models demonstrated that our designed peptide adopted a unique structure that was correlated with faster complex disassembly and a better gene-silencing effect. These studies further elucidate the siRNA nanocomplex delivery pathway and demonstrate the applicability of our stepwise strategy to the design of siRNA carriers capable of overcoming multiple challenges and achieving efficient delivery.