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Shinya Oishi

Publications and source records attributed to Shinya Oishi.

30 records · Page 2Linked to original sources
PubMed2004

Metastin and its variant forms suppress migration of pancreatic cancer cells.

Metastin, a post-translationally modified variant of KiSS1, was recently identified as an endogenous peptide agonist for a novel G-protein coupled receptor, hOT7T175 (AXOR12, GPR54). In this study, we analyzed the role of KiSS1 and hOT7T175 in both pancreatic cancer tissues and pancreatic cancer cell lines. Furthermore, we synthesized novel short variant forms of metastin and tested the inhibitory effect of those variants on in vitro cell functions that are relevant to metastasis. Pancreatic cancer tissues showed significantly lower expression of KiSS1 mRNA than normal tissues (p=0.018), while cancer tissues showed significantly higher expression of hOT7T175 mRNA than normal pancreatic tissues (p=0.027). In human pancreatic cancer cell lines, KiSS1 mRNA was highly expressed in 2 out of 6 pancreatic cancer cell lines, while hOT7T175 mRNA was expressed in all cell lines at various degrees. PANC-1 cells showed the highest expression of hOT7T175. Exogenous metastin did not suppress cell proliferation but significantly reduced the in vitro migration of PANC-1 cells (p<0.01). Metastin induced activation of ERK1 in PANC-1 and AsPC-1 cells. Finally, we synthesized 3 novel short variant forms of metastin, FM053a2TFA, FM059a2TFA, and FM052a4TFA. These metastin variants significantly suppressed the migration of PANC-1 cells and activated ERK1. These data suggest that the metastin receptor, hOT7T175, is one of the promising targets for suppression of metastasis, and that small metastin variants could be an anti-metastatic agent to pancreatic cancer.

Cell Line, Tumor↗
PubMed2004

Structure-activity relationship studies on cyclic RGD peptides utilizing novel alkene dipeptide isosteres.

A structure-activity relationship study was performed on cyclic RGD peptides using a combination of multisubstituted alkene dipeptide isosteres. To clarify the effects on bioactivity of a valine N-methyl group in the cyclo(-Arg-Gly-Asp-D-Phe-MeVal-) peptide developed by Kessler's group, novel D-Phe-Val-type isosteres with methyl-substituting groups on the olefin were designed and synthesized. Syntheses of D-Phe-psi[(E)-CH=CMe]-Val-type isosteres were carried out in essentially identical fashion to the previously reported preparation of psi[(E)-CH=CH]-type congeners. Alternatively, D-Phe-psi[(E)-CMe=CX]-Val-type isosteres (X=H or Me) were synthesized via stereoselective alkylation of beta-(1,3-oxazolidin-2-on-5-yl)-alpha,beta-enoates using organocopper reagents. The resulting four isosteres were utilized in either solution- or solid-phase peptide synthesis to afford the cyclic RGD peptidomimetics, cyclo(-Arg-Gly-Asp-D-Phe-psi[(E)-CX=CX]-Val-) (X=H or Me). alpha(V)beta(3) and alpha(IIb)beta(3) integrin antagonistic activities of the peptidomimetics along with Kessler's peptides were comparatively evaluated. In addition, structural calculations of these compounds by simulated annealing/energy minimization using dihedral and distance restraints derived from (1)H-NMR data in DMSO gave insight into the effects of the valine N-methyl group as well as the D-phenylalanine carbonyl oxygen.

Alkenes↗
PubMed2003

Biological activities of homologous loop regions in the laminin alpha chain G domains.

Laminin alpha chains (alpha1-alpha5 chains) have diverse chain-specific biological functions. The LG4 modules of laminin alpha chains consist of a 14-stranded beta-sheet (A-N) sandwich structure. Several biologically active sequences have been identified in the connecting loop regions. Here, we evaluated the biological activities of the loop regions of the E and F strands in the LG4 modules using five homologous peptides from each of the mouse alpha chains (EF-1: DYATLQLQEGRLHFMFDLG, alpha1 chain 2747-2765; EF-2: DFGTVQLRNGFPFFSYDLG, alpha2 chain 2808-2826; EF-3: RDSFVALYLSEGHVIFALG, alpha3 chain 2266-2284; EF-4: DFMTLFLAHGRLVFMFNVG, alpha4 chain 1511-1529; EF-5: SPSLVLFLNHGHFVAQTEGP, alpha5 chain 3304-3323). These homologous peptides showed chain-specific cell attachment and neurite outgrowth activities. Well organized actin stress fibers and focal contacts with vinculin accumulation were observed in fibroblasts attached on EF-1, whereas fibroblasts on EF-2 and EF-4 showed filopodia with ruffling. Fibroblast attachment to EF-2 and EF-4 was mediated by syndecan-2. In contrast, EF-1 promoted alpha2beta1 integrin-mediated fibroblast attachment and inhibited fibroblast attachment to a recombinant laminin alpha1 chain LG4-5. The receptors for EF-3 and EF-5 are unknown. Further, when the active core sequence of EF-1 was cyclized, utilizing two additional cysteine residues at both the N and C termini through a disulfide bridge, the cyclic peptide significantly enhanced integrin-mediated cell attachment. These results indicate that integrin-mediated cell attachment to the EF-1 sequence is conformation-dependent and that the loop structure is important for the activity. The homologous peptides, which promote either integrin- or syndecan-mediated cell attachment, may be useful for understanding the cell type- and chain-specific biological activities of the laminins.

Actins↗
PubMed2003

Direct electrophilic radiofluorination of a cyclic RGD peptide for in vivo alpha(v)beta3 integrin related tumor imaging.

The association of the alpha(v)beta(3) integrin with tumor metastasis and tumor related angiogenesis has been suggested. Therefore, by imaging the alpha(v)beta(3) receptor with PET, information concerning the tumor status could be obtained. Cyclic peptides including the RGD sequence, were radiolabeled by direct electrophilic fluorination with [(18)F]AcOF. In tumor-bearing mice, the labeled peptides accumulated at the tumor with a high tumor to blood ratio. These findings suggest that an assessment of tumor characteristics may be obtained by using these (18)F-labeled peptides.

Acetates↗
PubMed2002

Regio- and stereoselective synthesis of (E)-alkene trans-Xaa-Pro dipeptide mimetics utilizing organocopper-mediated anti-S(N)2' reactions.

Proline dipeptides (Xaa-Pro) exist as an equilibrium mixture of cis- and trans-rotamers, which depends on the energy barriers for imide isomerization. This conformation mixture contributes to both structure and function of proline-containing peptides and proteins. Structural motifs resembling these cis- or trans-conformers have served as useful tools for elucidating contributions of proline residues in the physicochemical and biological profiles of structures which contain them. Among such motifs are alkene dipeptide isosteres which mimic cis- or trans-imide using (Z)- or (E)-alkene, respectively. In this report, the first regio- and stereoselective syntheses of (E)-alkene dipeptide isosteres (20, 31, and 35) corresponding to trans-proline dipeptides are described. Key to the synthesis of these mimetics is the anti-S(N)2' reaction of vinyl aziridines such as 15 or vinyl oxazolidinones such as 28 and 32 with organocopper reagents "RCu" (R = CH(2)SiMe(2)(Oi-Pr)). Reaction of cis-vinylaziridine 15 derived from L-serine with organocopper reagent gave a precursor of the trans-L-Ser-D-Pro type alkene isosteres 20, accompanied by an S(N)2 side product. One limitation with the use of such aziridine-mediated methodology is formation of the corresponding trans-aziridine 22, which leads to L-L type isosteres, that is unstable and obtainable only in low yield. On the other hand, both isomers of oxazolidinone derivatives can be easily obtained from N-Boc-protected amino alcohols. The reaction of trans- 28 or cis-oxazolidinone derivative 32 with organocopper reagents proceeds quantitatively with high regio- and diastereoselectivities in anti-S(N)2' fashion. Subsequent oxidative treatment of the newly introduced isopropoxydimethylsilylmethyl group yields trans-L-Ser-L-Pro 31 or trans-L-Ser-D-Pro type isosteres 35, respectively. Of note, synthesized isostere 31 can also be converted to trans-phosphoSer-Pro 42 and trans-Cys-Pro mimetics 44. The present synthetic methodology affords trans-Xaa-Pro alkene-type dipeptide isosteres in high yield with relatively simple manipulation.

Alkenes↗
PubMed2002

Diastereoselective synthesis of new psi[(E)-CH=CMe]- and psi[(Z)-CH=CMe]-type alkene dipeptide isosteres by organocopper reagents and application to conformationally restricted cyclic RGD peptidomimetics.

Diastereoselective synthesis of new psi[(E)-CH=CMe]- and psi[(Z)-CH=CMe]-type alkene dipeptide isosteres corresponding to dipeptides having one N-methylamino acid, and application to bioactive peptides, are described. In a key reaction introducing the chiral alpha-alkyl group of the isosteres, organocopper-mediated alkylation of syn-beta-methylated gamma-mesyloxy-alpha,beta-enoate 26a afforded E- and Z-isomers of anti-S(N)2' products in a solvent-dependent manner. The resulting two isosteres, D-Phe-psi[(E)-CH=CMe]-L-Val 27a and D-Phe-psi[(Z)-CH=CMe]-L-Val 28b, which corresponded to trans- and cis-conformers of D-Phe-L-MeVal, respectively, were utilized in a structure-activity relationship study on cyclic RGD peptides 1 and 2, in company with a psi[(E)-CH=CH]-type alkene dipeptide isostere, D-Phe-psi[(E)-CH=CH]-L-Val. The cyclic isostere-containing pseudopeptides 3, 4, and 40 were synthesized and biological activity against integrin alpha(V)beta(3) and alpha(IIb)beta(3) receptors were also evaluated.

Alkenes↗
PubMed2002

Diastereoselective synthesis of psi[(E)-CH=CMe]- and psi[(Z)-CH=CMe]-type dipeptide isosteres by organocopper-mediated anti-S(N)2' reaction.

[reaction: see text] Acyclic psi[(E)-CH=CMe]- and psi[(Z)-CH=CMe]-type dipeptide isosteres were efficiently synthesized. In a key reaction, alpha-alkylation of gamma-mesyloxy-beta-methyl-alpha,beta-unsaturated esters with organocyanocuprates in diethyl ether or tetrahydrofuran preferentially afforded the psi[(E)-CH=CMe]- or psi[(Z)-CH=CMe]-isomer, respectively, via anti-S(N)2' mechanism.

Alkylation↗
PubMed2002

Diastereoselective synthesis of psi[(E)-CMe=CH]- and psi[(E)-CMe=CMe]- type dipeptide isosteres based on organocopper-mediated anti-S(N)2' reaction.

[reaction: see text] A straightforward synthetic route for the synthesis of diastereomerically pure psi[(E)-CMe=CH]- and psi[(E)-CMe=CMe]-type dipeptide isosteres was developed on the basis of regio- and stereoselective anti-S(N)2' alkylation of 3-(N-Boc-5-methyl-4-substituted-oxazolidin-2-on-5-yl)acrylates with organocopper reagents.

Alkylation↗
PubMed2002

Synthesis and evaluation of pseudopeptide analogues of a specific CXCR4 inhibitor, T140: the insertion of an (E)-alkene dipeptide isostere into the betaII'-turn moiety.

A 14-residue peptide, T140, strongly inhibits the T-cell line-tropic HIV-1 (X4-HIV-1) infection, since this peptide functions as a specific antagonist against a chemokine receptor, CXCR4. T140 takes an antiparallel beta-sheet structure with a type II' beta-turn. In the present paper, we have designed and synthesized several T140 analogues, in which an (E)-alkene dipeptide isostere was inserted into the type II' beta-turn moiety, as a bridging study to develop nonpeptidic CXCR4 inhibitors. It has been proven that the turn region of T140 can be replaced by the above surrogate with the maintenance of strong anti-HIV activity.

Anti-HIV Agents↗
PubMed2002

Synthesis of allenes from allylic alcohol derivatives bearing a bromine atom using a palladium(0)/diethylzinc system.

A general and efficient synthesis of allenes using a palladium(0)/diethylzinc system is described. Treatment of mesylates or trichloroacetates of (E)- or (Z)-2-bromoalk-2-en-1-ols with diethylzinc in the presence of a catalytic amount of palladium(0) affords allenes bearing an aminoalkyl, alkyl, or aryl substituent(s) in good to high yields. No transfer of chirality from the stereogenic center carrying the mesyloxy group to the allene was observed.

Journal Article↗
PubMed2002

Certification of the critical importance of L-3-(2-naphthyl)alanine at position 3 of a specific CXCR4 inhibitor, T140, leads to an exploratory performance of its downsizing study.

We have previously found that a 14-amino acid residue-peptide, T140, inhibits infection of target cells by T cell line-tropic HIV-1 (X4-HIV-1) through its specific binding to a chemokine receptor, CXCR4. Here, the importance of an L-3-(2-naphthyl)alanine (Nal) residue at position 3 in T140 for high anti-HIV activity and inhibitory activity against Ca(2+) mobilization induced by stromal cell-derived factor (SDF)-1alpha-stimulation through CXCR4 has initially been shown by the synthesis and biological evaluation of several analogues, where Nal(3) is substituted by diverse aromatic amino acids. Next, the order of the N-terminal 3 residues (Arg(1)-Arg(2)-Nal(3)) has been proved to be important from the structure--activity relationship (SAR) study shuffling these residues. Based on these results, we have found 10-residue peptides possessing modest anti-HIV activity by systematic antiviral evaluation of a series of synthetic, shortened analogues of T140.

Alanine↗