Transduced PEP-1-Grb7 fusion protein suppressed LPS-induced COX-2 expression

The traditional Japanese formula keishibukuryogan inhibits the production of inflammatory cytokines by dermal endothelial cells

Keishibukuryogan (KBG) is one of the traditional herbal formulations widely administered to patients with blood stagnation for improving blood circulation; currently, it is the most frequently prescribed medicine in Japan. KBG has been reported to improve conjunctional microcirculation. The aim of this study was to evaluate the role of KBG and paeoniflorin, a bioactive compound of KBG, in inhibiting the production of inflammatory cytokines using human dermal microvessel endothelial cells (HDMECs). The authors observed that lipopolysaccharide (LPS; 1 μg/mL) stimulated the secretion of proinflammatory cytokines in HDMECs. KBG treatment (10 mg/mL) significantly suppressed the mRNA levels of migration inhibitory factor (MIF), interleukin (IL)-6, IL-8, and tumor necrosis factor (TNF)-α in LPS-stimulated cultured HDMECs. Similarly, paeoniflorin significantly suppressed the mRNA levels of these cytokines in LPS-stimulated cultured HDMECs. ELISA showed that KBG and paeoniflorin suppressed the production of MIF, IL-6, IL-8, and TNF-α in LPS-stimulated HDMECs. Moreover, KBG and paeoniflorin decreased the expression of cyclooxygenase-2 and inducible nitric oxide synthase (iNOS) in these cells. These results suggest that KBG may be useful for improving microvascular inflammation in patients with skin diseases.

Chemopreventive effects of polysaccharides extract from Asterina pectinifera on HT-29 human colon adenocarcinoma cells

We examined the effects of polysaccharides extracted from Asterina pectinifera on the activities of quinone reductase (QR), glutathione S-transferase (GST), ornithine decarboxylase (ODC), cyclooxygenase (COX)-2 and glutathione (GSH) levels in HT-29 human colon adenocarcinoma cells. We found that the polysaccharides extract induced QR activity in a dose-dependent manner over a concentration range of 20 approximately 60 microg/ml and increased GST activity as much as 1.4-fold over controls. GSH levels were increased 1.3- and 1.5-fold with the extract at 40 and 60 microg/ml, respectively. The activity and protein expression of ODC in 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced colon cancer cells was inhibited by the extract. The polysaccharides suppressed TPA-induced prostaglandin (PG) production. These data indicate that polysaccharides from A. pectinifera increase phase II detoxification enzyme activity and inhibit ODC and COX-2 activities in HT-29 human colon adenocarcinoma cells. Consequently, this effect may contribute to the protective effect of polysaccharides from A. pectinifera against colon cancer.

Tyrosine phosphorylation of growth factor receptor-bound protein-7 by focal adhesion kinase in the regulation of cell migration, proliferation, and tumorigenesis

We have previously reported that growth factor receptor-bound protein-7 (Grb7), an Src-homology 2 (SH2)-containing adaptor protein, enables interaction with focal adhesion kinase (FAK) to regulate cell migration in response to integrin activation. To further elucidate the signaling events mediated by FAK*Grb7 complexes in promoting cell migration and other cellular functions, we firstly examined the phosphorylated tyrosine site(s) of Grb7 by FAK using an in vivo mutagenesis. We found that FAK was capable of phosphorylating at least 2 of 12 tyrosine residues within Grb7, Tyr-188 and Tyr-338. Moreover, mutations converting the identified Tyr to Phe inhibited integrin-dependent cell migration as well as impaired cell proliferation but not survival compared with the wild-type control. Interestingly, the above inhibitory effects caused by the tyrosine phosphorylation-deficient mutants are probably attributed to their down-regulation of phospho-Tyr-397 of FAK, thereby implying a mechanism by competing with wild-type Grb7 for binding to FAK. Consequently, these tyrosine phosphorylation-deficient mutants evidently altered the phospho-Tyr-118 of paxillin and phosphorylation of ERK1/2 but less on phospho-Ser-473 of AKT, implying their involvement in the FAK*Grb7-mediated cellular functions. Additionally, we also illustrated that the formation of FAK*Grb7 complexes and Grb7 phosphorylation by FAK in an integrin-dependent manner were essential for cell migration, proliferation and anchorage-independent growth in A431 epidermal carcinoma cells, indicating the importance of FAK*Grb7 complexes in tumorigenesis. Our data provide a better understanding on the signal transduction event for FAK*Grb7-mediated cellular functions as well as to shed light on a potential therapeutic in cancers.

Inhibition of LPS-induced cyclooxygenase 2 and nitric oxide production by transduced PEP-1-PTEN fusion protein in Raw 264.7 macrophage cells

Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) is a tumor suppressor. Although it is well known to have various physiological roles in cancer, its inhibitory effect on inflammation remains poorly understood. In the present study, a human PTEN gene was fused with PEP-1 peptide in a bacterial expression vector to produce a genetic in-frame PEP-1-PTEN fusion protein. The expressed and purified PEP-1-PTEN fusion protein were transduced efficiently into macrophage Raw 264.7 cells in a time- and dose- dependent manner when added exogenously in culture media. Once inside the cells, the transduced PEP-1-PTEN protein was stable for 24 h. Transduced PEP-1-PTEN fusion protein inhibited the LPS-induced cyclooxygenase 2 (COX-2) and iNOS expression levels in a dose-dependent manner. Furthermore, transduced PEP-1-PTEN fusion protein inhibited the activation of NF-kappaB induced by LPS. These results suggest that the PEP-1-PTEN fusion protein can be used in protein therapy for inflammatory disorders.

Intracellular delivery of proteins into mouse Müller glia cells in vitro and in vivo using Pep-1 transfection reagent

Direct protein transfection is a potentially valuable tool for studying protein function in basic and clinical research. A major challenge is to enable a sufficiently large amount of protein to penetrate the plasma membrane of the transfected cells. Pep-1, a protein transfection reagent, was evaluated for its ability and efficiency in delivering proteins and antibodies into mouse Müller cells in vitro and in vivo. Pep-1 delivered active beta-galactosidase enzyme and antibodies (non-specific IgG and Cy3-conjugated anti-vimentin) into cultured Müller cells with high efficiency. Transfection efficiency increased with increasing concentration of the protein in the complex and with incubation time. Following intravitreal injection of Pep-1/IgG complexes in vivo, retinal histology was preserved and immunostaining showed that the antibodies were distributed widely across the retinal surface, with the most intense staining located near the retino-vitreal border. For complexes using non-specific IgG, double staining with anti-glutamine synthetase identified many IgG-positive cells as Müller glia. IgG immunoreactivity was also detected in the cytoplasm and occasionally in the nuclei of inner retinal neurons. Dark-adapted flash electroretinogram (ERG) recordings from injected eyes were nearly identical to ERG recordings from control eyes, suggesting that injection of Pep-1/IgG complex has minimal effects on retinal function. Therefore, Pep-1 is a useful tool for intracellular delivery of antibodies to study the role of proteins in living cells.