Macrophage inflammatory protein-1α induces osteoclast formation by activation of the MEK/ERK/c-Fos pathway and inhibition of the p38MAPK/IRF-3/IFN-β pathway

Multiple myeloma (MM) is a bone disease that affects many individuals. It was recently reported that macrophage inflammatory protein (MIP)-1α is constitutively secreted by MM cells. MIP-1α causes bone destruction through the formation of osteoclasts (OCs). However, the molecular mechanism underlying MIP-1α-induced OC formation is not well understood. In the present study, we attempted to clarify the mechanism whereby MIP-1α induces OC formation in a mouse macrophage-like cell line comprising C7 cells. We found that MIP-1α augmented OC formation in a concentration-dependent manner; moreover, it inhibited IFN-β and ISGF3γ mRNA expression, and IFN-β secretion. MIP-1α increased the expressions of phosphorylated ERK1/2 and c-Fos and decreased those of phosphorylated p38MAPK and IRF-3. We found that the MEK1/2 inhibitor U0126 inhibited OC formation by suppressing the MEK/ERK/c-Fos pathway. SB203580 induced OC formation by upregulating c-fos mRNA expression, and SB203580 was found to inhibit IFN-β and IRF-3 mRNA expressions. The results indicate that MIP-1α induces OC formation by activating and inhibiting the MEK/ERK/c-Fos and p38MAPK/IRF-3 pathways, respectively, and suppressing IFN-β expression. These findings may be useful in the development of an OC inhibitor that targets intracellular signaling factors.     

Induction of IFN-γ by a highly branched 1,3-β-d-glucan from Aureobasidium pullulans in mouse-derived splenocytes via dectin-1-independent pathways

We have previously elucidated the precise structure of a unique type of 1,3-β-d-glucan, AP–FBG (Aureobasidium pullulans-fermented β-d-glucan), from the fungus A. pullulans and found that AP–FBG strongly induced the production of various cytokines in DBA/2 mouse-derived splenocytes in vitro. However, the mechanism(s) of action of AP–FBG on in vitro mouse primary cells have not been characterized in detail. Herein, we report that the production of IFN-γ in DBA/2 mouse-derived splenocytes by AP–FBG was not inhibited following treatment with an anti-dectin-1 neutralizing antibody. In addition, AP–FBG not only failed to activate dectin-1-mediated signaling pathways, examined by a reporter gene assay but also failed to bind to dectin-1, a pivotal receptor for 1,3-β-d-glucan. Taken together, AP–FBG induced cell activation via dectin-1-independent pathways.     

Overexpression of ADAM9 enhances growth factor-mediated recycling of E-cadherin in human colon cancer cell line HT29 cells

Growth factor-mediated stimulation of epithelial cells induces the disassembly of E-cadherin-mediated cell-cell adhesion. We found that overexpression of a disintegrin and metalloprotease 9 (ADAM9) enhanced growth factor-mediated induction of endocytosis and dynamic recycling of E-cadherin in HT29 human colon cancer cells. In addition, ubiquitination and degradation of E-cadherin were reduced in these cells. ADAM9 constitutively interacted with E-cadherin, and the two proteins co-localized at the plasma membrane of HT29 cells. Administration of a metalloprotease inhibitor or overexpression of an ADAM9 mutant lacking metalloprotease activity attenuated growth factor-dependent endocytosis and recycling of E-cadherin as well as scattering of HT29 cells. These results suggest that the metalloprotease activity of ADAM9 mediates growth factor-induced endocytosis and dynamic recycling of E-cadherin and prevents E-cadherin degradation.     

Host specificity and population dynamics of a sponge-endosymbiotic bivalve

We assessed the host-use pattern of the sponge-endosymbiotic bivalve Vulsella vulsella and its demographic consequences in an inland sea in Okinawa Island, Japan. Vulsella vulsella utilized only one massive globular sponge species Spongia sp. as a host, and no Spongia sp. without V. vulsella were found. Individual sponges contained 9-248 live bivalves and 0-222 dead bivalves. The densities of live and dead bivalves in individual sponges were approximately constant irrespective of sponge size, indicating that available space is very scarce inside each sponge. The size distribution of bivalves was skewed to small, young individuals less than 30 mm in shell height, although the estimated largest possible size was 106 mm. The bivalve population at each sampling date was composed of three yearly cohorts, and recruitment of juveniles occurred in the summer. The bivalves became sexually mature as males within one year after recruitment and changed sex from male to female as they grew. The size and sex distributions of the bivalve were largely similar among sponges regardless of sponge size, suggesting that the recruitment, growth, longevity, and sex change of the bivalve were strictly regulated, probably by the high water temperature and strong waves generated by typhoons in summer months.     

Tamoxifen inhibits tumor cell invasion and metastasis in mouse melanoma through suppression of PKC/MEK/ERK and PKC/PI3K/Akt pathways

In melanoma, several signaling pathways are constitutively activated. Among these, the protein kinase C (PKC) signaling pathways are activated through multiple signal transduction molecules and appear to play major roles in melanoma progression. Recently, it has been reported that tamoxifen, an anti-estrogen reagent, inhibits PKC signaling in estrogen-negative and estrogen-independent cancer cell lines. Thus, we investigated whether tamoxifen inhibited tumor cell invasion and metastasis in mouse melanoma cell line B16BL6. Tamoxifen significantly inhibited lung metastasis, cell migration, and invasion at concentrations that did not show anti-proliferative effects on B16BL6 cells. Tamoxifen also inhibited the mRNA expressions and protein activities of matrix metalloproteinases (MMPs). Furthermore, tamoxifen suppressed phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt through the inhibition of PKCα and PKCδ phosphorylation. However, other signal transduction factor, such as p38 mitogen-activated protein kinase (p38MAPK) was unaffected. The results indicate that tamoxifen suppresses the PKC/mitogen-activated protein kinase kinase (MEK)/ERK and PKC/phosphatidylinositol-3 kinase (PI3K)/Akt pathways, thereby inhibiting B16BL6 cell migration, invasion, and metastasis. Moreover, tamoxifen markedly inhibited not only developing but also clinically evident metastasis. These findings suggest that tamoxifen has potential clinical applications for the treatment of tumor cell metastasis.     

Proteomic analysis of autoantibodies in patients with hepatocellular carcinoma

To detect autoantibodies that could be diagnostic markers for hepatocellular carcinoma (HCC), we analyzed serum autoantibodies comprehensively that showed immunoreactivity to proteins in tumor tissue obtained from patients with HCC. Fifteen paired samples of HCC tissue and corresponding nontumorous liver tissue as well as five normal liver tissue samples were used in the study. A combination of proteomics and SEREX (serologic analysis of recombinant cDNA expression libraries) technique was used. Tissue proteins were separated by 2-DE, transferred onto PVDF membranes, and immunoblotted with autologous sera. By comparing each immunoblot pattern, we identified four immunoreactive spots with stronger staining intensity in tumorous tissues than in corresponding nontumorous tissues and in normal liver tissues. Matched proteins on 2-DE gels were identified by LC-MS/MS. These immunoreactive proteins were heat shock 70 kDa protein 1 (HSP70), glyceraldehyde 3-phosphate dehydrogenase, peroxiredoxin, and manganese superoxide dismutase (Mn-SOD). In HCC sera, occurrences of autoantibodies against these proteins were 7/15 (46.7%), 5/15 (33.3%), 5/15 (33.3%), and 6/15 (40.0%), respectively, whereas 2/20 (10.0%), 7/20 (35.0%), 0/20 (0.0%), and 2/20 (10.0%) were in control sera. Immunoblot analysis using commercially available purified proteins was performed to confirm the specificity of autoantibodies. By statistical analysis, autoantibodies against HSP70, peroxiredoxin, and Mn-SOD showed significantly high-frequency immunoreaction in HCC sera. The three antibodies were considered patient-specific antibodies in HCC and may be candidate diagnostic biomarkers for HCC.     

Synthesis and biological evaluation of vitamin K derivatives as angiogenesis inhibitor

Ten vitamin K₃ derivatives were synthesized and screened for anti-angiogenic activity. Results indicated that amine derivatives (1a–d) exerted a stronger inhibition effect on angiogenesis compared to alkyl derivatives (2a–d). In addition to being the most potent inhibitor, 1b also suppressed human umbilical vein endothelial cell tube formation and proliferation. These results suggest that vitamin K₃ amine derivatives with shorter alkyl chains, such as 1b, could be useful for developing anti-angiogenic agents.     

Stereoselective glycosylations using benzoylated glucosyl halides with inexpensive promoters

Reactions of O-benzoylated glucopyranosyl halide (I, Br), isolated or generated in situ from per-benzoylated glucose (8a) and trimethylsilyl halide, with various alcohols were efficiently promoted by zinc halide (Cl, Br) or N-bromosuccinimide with a catalytic ZnI₂ to give the corresponding 1,2-trans-β-glucosides in good to high yields. When the anomeric halogenation of 8a was carried out in the presence of reactive alcohols, 1,2-cis--glucosides were selectively formed.     

Diethyl pyrocarbonate modification abolishes fast electron accepting ability of cytochrome b561 from ascorbate but does not influence electron donation to monodehydroascorbate radical: identification of the modification sites by mass spectrometric analysis

Cytochrome b(561) from bovine adrenal chromaffin vesicles contains two heme B prosthetic groups and transports electron equivalents across the vesicle membranes to convert intravesicular monodehydroascorbate radical to ascorbate. To elucidate the mechanism of the transmembrane electron transfer, effects of the treatment of purified cytochrome b(561) with diethyl pyrocarbonate, a reagent specific for histidyl residues, were examined. We found that when ascorbate was added to the oxidized form of diethyl pyrocarbonate-treated cytochrome b(561), less than half of the heme iron was reduced but with a very slow rate. In contrast, radiolytically generated monodehydroascorbate radical was oxidized rapidly by the reduced form of diethyl pyrocarbonate-modified cytochrome b(561), as observed for untreated cytochrome b(561). These results indicate that the heme center specific for the electron acceptance from ascorbate was perturbed by the modification of amino acid residues nearby. We identified the major modification sites by mass spectrometry as Lys85, His88, and His161, all of which are fully conserved and located on the extravesicular side of cytochrome b(561) in the membranes. We suggest that specific N-carbethoxylation of the histidyl ligands of the heme b at extravesicular side abolishes the electron-accepting ability from ascorbate.