Improvement of lentiviral vector-mediated gene transduction by genetic engineering of the structural protein Pr55 Gag

The lentiviral vector is a promising tool for human gene therapy because of its ability to transduce genes into many cell types. However, one of the technical problems associated with the lentiviral vector is that lentiviral titers in current production systems are relatively low compared with the other viral vectors. In this study, we provide genetic evidence that the attachment of heterologous myristoylation (myr) signals on the amino-terminus of human immunodeficiency virus type 1 Pr55(Gag) (Gag) can increase the viral yield up to 10-fold, leading to the enhancement of gene transduction in many cell lines. The myr signal Gag constructs behaved similarly to the wild-type Gag in targeting to detergent-resistant membrane compartments, Vps4-dependence for viral budding, and virion morphology. However, the myr signal Gag constructs showed improved oligomerization efficiency as measured by bioluminescence resonance energy transfer in living cells, contributing to increased viral production and efficient activation of the viral protease responsible for virion maturation. The genetically modified Gag represents the next generation lentiviral vector, and should contribute to the success of many lentiviral vector applications.

[New method for preparing proximal anastomotic system]

Heartstring is a useful device. However, the device failure at the time of loading the seal into the delivery device is a troublesome issue. To avoid this problem, we invent a new method using 2 tourniquets made of 5 mm-wide woven Teflon tapes and plastic tubes. Using our method, the loading procedure became easier and more reliable.

New HIV-Drug Inhibits In Vitro Bladder Cancer Migration and Invasion

OBJECTIVE

The CXCR4/CXCL12 axis appears crucial in the metastasis of bladder cancer. Our aim was to evaluate the potency of the CXCR4 antagonist, 4F-benzoyl-TE14011 (4F-bTE), as an anti-metastatic drug in this disease. In this study, we assessed the ability of 4F-bTE to inhibit tumor cell motility, invasion through extracellular matrix (ECM), matrix metalloproteinase (MMP) secretion and cytoskeletal responses to chemokine.

METHODS

To assess the degree to which cells could migrate and invade ECM under various conditions, we used TCCSUP bladder cancer cells in a Boyden chamber system. To monitor actin polymerization, we stained cells on chamber slides with AlexaFluor 594 phalloidin. To measure matrix-metalloproteinase-2 and -9 (MMP) activity, we used gelatin zymography. To assess the effects of the CXCR4 antagonist 4F-bTE on each of the above parameters, we exposed bladder cancer cells either to chemokine CXCL12, alone, or to both CXCL12 and 4F-bTE. We also monitored cells for apoptotic and necrotic changes during drug treatment.

RESULTS

The CXCR4 antagonist 4F-bTE markedly decreased CXCL12-induced bladder cancer cell migration and ECM invasion in Boyden chamber assays. The antagonist also blocked chemokine-induced actin polymerization as well as the induction of MMP-2 and MMP-9 in these cells.

CONCLUSION

The CXCR4 antagonist 4F-bTE has the potential to inhibit expression of the metastatic phenotype and may provide therapeutic value to patients.

A single treatment with microcapsules containing a CXCR4 antagonist suppresses pulmonary metastasis of murine melanoma

Biodegradable poly D,L-lactic acid (PLA, molecular weight: ca. 5000) microcapsules containing a CXCR4 antagonist (4F-benzoyl-TE14011) were prepared (4F-benzoyl-TE14011-PLA), and their anti-metastatic activity was evaluated in mice. A single subcutaneous administration of 4F-benzoyl-TE14011-PLA significantly reduced the number of colonies formed by pulmonary metastasis of B16-BL6 melanoma cells expressing CXCR4. The same dose of 4F-benzoyl-TE14011 in a single or a series of treatments affected little. The substance 4F-benzoyl-TE14011 dose-dependently suppressed B16-BL6 cell growth. In the cells cultured with SDF-1, a more potent suppression was observed. 4F-Benzoyl-TE14011 was rapidly released from 4F-benzoyl-TE14011-PLA for an initial period, both in vitro and in vivo. A steady release was thereafter observed. Therefore, this drug release profile might contribute to prevention of melanoma metastasis at the steps involving the migration and cell growth. These results also show that a sustained drug release formulation could be a useful drug delivery system for CXCR4 antagonists.

[Development of selective antagonists against an HIV second receptor]

The authors have discovered a highly selective CXCR4 antagonist, T22 ([Tyr5,12, Lys7]-polyphemusin II), and its shortened potent analogs, T140 and TC14012, which strongly inhibit the T-cell line-tropic HIV-1 (X4-HIV-1) infection through their specific binding to a chemokine receptor, CXCR4. CXCR4 is a major coreceptor (second receptor) for the entry of X4-HIV-1 into T-cells. These peptides have been found through the structure-activity relationship (SAR) study on tachyplesins and polyphemusins, which function as self-defense peptides of horseshoe crabs with immature immune systems. T140 and TC14012 showed the highest level of anti-HIV activity and antagonism of target cell entry by X4-HIV-1 among all the CXCR4 antagonists that have been reported to date. Additionally, bifunctional anti-HIV agents based on the specific CXCR4 antagonists (T140 analogs)-3'-azido-3'-deoxythymidine (AZT) conjugation have been synthesized and evaluated, since T140 analogs can possibly work as a carrier of AZT targeting T-cells due to their specific affinity for CXCR4 on T-cells. T22 have two disulfide bonds and a Trp residue in the molecule. In connection with this study, novel facile and side-reaction-free methodologies for disulfide bond formation have been established for the increase of the efficiency of SAR studies. Furthermore, the completely stereocontrolled synthetic process for a couple of (E)-alkene dipeptide isosteres starting from L-amino acid has been established in order to facilitate nonpeptidylation studies on peptide-lead candidates. In this review, the authors wish to summarize our recent research on the development of specific antagonists against the HIV second receptor CXCR4, involving studies on the establishment of efficient methodologies for the facile synthesis of peptides and peptide mimetics.

Peptide-lead CXCR4 antagonists with high anti-HIV activity

The highly selective CXCR4 antagonist, T-22 ([Tyr5,12,Lys7]-polyphemusin II), and its shortened potent analogs, T-140 and TC-14012, strongly inhibit T-cell line-tropic HIV-1 (X4-HIV-1) infection through their specific binding to a chemokine receptor, CXCR4. These peptides were found through studies of the structure-activity relationships of tachyplesins and polyphemusins, which function as self-defence peptides of horseshoe crab's immature immune systems. T-140 and TC-14012 possess the highest level of anti-HIV activity and antagonism of target cell entry by X4-HIV-1 among all the CXCR4 antagonists that have been reported to date.

Synthesis and evaluation of bifunctional anti-HIV agents based on specific CXCR4 antagonists-AZT conjugation

We have previously found that T140, a 14-amino acid residue peptide, inhibits infection of target cells by T cell-line-tropic strains of HIV-1 (X4-HIV-1) through its specific binding to a chemokine receptor, CXCR4. Here, we report synthesis and evaluation of bifunctional anti-HIV compounds, which are composed of T140 analogues and a reverse transcriptase inhibitor, 3'-azido-3'-deoxythymidine (AZT). Novel conjugated analogues have been proved to have the ability for controlled release of AZT in neutral aqueous media as well as mouse and feline sera, and high selectivity indexes (SIs, 50% cytotoxic concentration/50% effective concentration) caused by a synergistic effect of two different regenerating agents. Thus, these bifunctional compounds have several potential advantages. T140 analogues can possibly work as a carrier of AZT targeting T cells due to their specific affinity for CXCR4 on T cells. A synergistic effect by two types of regenerating agents may enable drug dosage to be reduced, and thus it may effectively suppress toxic side effects and the appearance of drug-resistant virus.

Development of specific CXCR4 inhibitors possessing high selectivity indexes as well as complete stability in serum based on an anti-HIV peptide T140

We previously reported a truncated polyphemusin peptide analogue, T140, which efficiently inhibits infection of target cells by T-cell line-tropic strains of HIV-1 (X4-HIV-1) through its specific binding to a chemokine receptor, CXCR4. We have found that T140 is not stable in feline serum due to the cleavage of the C-terminal Arg,(14) indispensable for anti-HIV activity. On the other hand, a C-terminally amidated analogue of T140, TZ14004, has been found to be completely stable in incubation in the serum for 2 days. The C-terminal amide is thought to be needed for stability in serum. However, TZ14004 does not have fairly strong anti-HIV activity, but has relatively strong cytotoxicity, probably due to an increase by +1 charge from total +7 charges of T140. In our previous study, the number of total +6 charges seemed to be a suitable balance between activity and cytotoxicity. In this study, we have conducted a double-L-citrulline (Cit)-scanning study on TZ14004 based on the C-terminally amidated form in due consideration of the total net charges in the whole molecule to find novel effective CXCR4 inhibitors, TN14003 ([Cit(6)]-T140 with the C-terminal amide) and TC14012 ([Cit(6), D-Cit(8)]-T140 with the C-terminal amide), which possess high selectivity indexes (SIs) and complete stability in feline serum.

Biological and genetic characterization of a human immunodeficiency virus strain resistant to CXCR4 antagonist T134

The chemokine receptors CXCR4 and CCR5 are considered to be potential targets for the inhibition of HIV-1 replication. We have reported that T134 and T140 inhibited X4 HIV-1 infection specifically because they acted as CXCR4 antagonists. In the present study, we have generated a T134-resistant virus (trHIV-1(NL4-3)) in a cell culture with gradually increasing concentrations of the compound. The EC(50) of T134 against trHIV-1(NL4-3) recovered after 145 passages was 15 times greater than that against wild-type HIV-1(NL4-3). This adapted virus was resistant to other CXCR4 antagonists, T140, AMD3100, and ALX40-4C, and SDF-1; from 10 to 145 times greater than that against wild-type HIV-1(NL4-3). On the other hand, T134, T140, and ALX40-4C were still active against AMD3100-resistant viruses (arHIV-1(018A)). The trHIV-1(NL4-3) contained the following mutations in the V3 loop of gp120: N269K, Q278T, R279K, A284V, F285L, V286Y, I288T, K290E, N293D, M294I, and Q296K; an insertion of T at 290; and Delta274-275 (SI). In addition, many other mutations were recognized in the V1, V2, and V4 domains. Thus, resistance to T134 may be the consequence of amino acid substitutions in the envelope glycoprotein of X4 HIV-1. The trHIV-1(NL4-3) could not utilize CCR5 as an HIV infection coreceptor, although many amino acid substitutions were recognized. The trHIV-1(NL4-3) acquired resistance to vMIP II, which could inhibit both X4 and R5 HIV-1 infection. However, neither the ligands of CCR5, RANTES, and MIP-1alpha, nor a CCR5 low molecular antagonist, TAK-779, were able to influence the infection of trHIV-1(NL4-3). Those results indicated that alternation of coreceptor usage of trHIV-1(NL4-3) was not induced.

Increase of R5 HIV-1 infection and CCR5 expression in T cells treated with high concentrations of CXCR4 antagonists and SDF-1

The chemokine receptors CXCR4 and CCR5 are considered to be potential targets for the inhibition of HIV-1 replication. We found that the synthetic peptides T134 and T140 (see text for full names) inhibited X4 HIV-1 infection with selectivity and low toxicity because they acted as CXCR4 antagonists. However, high concentrations of T134, T140, and ALX40-4C (see text for full name) increased the expression of CCR5 and R5 HIV-1 infection, as did stromal cell-derived factor 1 (SDF-1). In contrast to CXCR4 antagonists and SDF-1, viral monocyte inflammatory protein (vMIP) II inhibited not only anti-CXCR4 monoclonal antibody (MAb) but also inhibited anti-CCR5 MAb binding to human peripheral blood mononuclear cells, and inhibited both X4 and R5 HIV-1 strains. T134, T140, ALX40-4C, and SDF-1 increased viral transcription in the treated cells. In addition, ALX40-4C and SDF-1 also increased nuclear transcription factor (NF)-kappaB. However, the mechanisms of action of T134 and T140 are different from those of clinically used anti-HIV drugs. Thus, synergistic activities were observed in the concomitant treatment with T134 and reverse transcriptase inhibitors or protease inhibitors. Our findings, presented here, are noteworthy in regard to the potential clinical use of these agents as drugs for the treatment of AIDS.

Conformational study of a highly specific CXCR4 inhibitor, T140, disclosing the close proximity of its intrinsic pharmacophores associated with strong anti-HIV activity

We report the solution structure of T140, a truncated polyphemusin peptide analogue that efficiently inhibits infection of target cells by T-cell line-tropic strains of HIV-1 through its specific binding to a chemokine receptor, CXCR4. Nuclear magnetic resonance analysis and molecular dynamic calculations revealed that T140 has a rigidly structured conformation constituted by an antiparallel beta-sheet and a type II' beta-turn. A protuberance is formed on one side of the beta-sheet by the side-chain functional groups of the three amino acid residues (L-3-(2-naphthyl)alanine, Tyr5 and Arg14), each of which is indispensable for strong anti-HIV activity. These findings provide a rationale to dissect the structural basis for the ability of this compound to block the interaction between CXCR4 and envelope glycoproteins from T-tropic strains of HIV-1.

Pharmacophore identification of a specific CXCR4 inhibitor, T140, leads to development of effective anti-HIV agents with very high selectivity indexes

A polyphemusin peptide analogue, T22 ([Tyr(5,12), Lys7]-polyphemusin II), and its shortened potent analogues, T134 (des-[Cys(8,13), Tyr(9,12)]-[D-Lys10, Pro11, L-citrulline16]-T22 without C-terminal amide) and T140 [[L-3-(2-naphthyl)alanine3]-T134], strongly inhibit the T-cell line-tropic (T-tropic) HIV-1 infection through their specific binding to a chemokine receptor, CXCR4. T22 is an extremely basic peptide possessing five Arg and three Lys residues in the molecule. In our previous study, we found that there is an apparent correlation in the T22-related peptides between the number of total positive charges and anti-HIV activity or cytotoxicity. Here, we have conducted the conventional Ala-scanning study in order to define the anti-HIV activity pharmacophore of T140 (the strongest analogue among our compounds) and identified four indispensable amino acid residues (Arg2, Nal3, Tyr5, and Arg14). Based on this result, a series of L-citrulline (Cit)-substituted analogues of T140 with decreased net positive charges have been synthesized and evaluated in terms of anti-HIV activity and cytotoxicity. As a result, novel effective inhibitors, TC14003 and TC14005, possessing higher selectivity indexes (SIs, 50% cytotoxic concentration/50% effective concentration) than that of T140 have been developed.

Conformationally constrained analogues of diacylglycerol (DAG). 17. Contrast between sn-1 and sn-2 DAG lactones in binding to protein kinase C

In previous work, we have obtained potent protein kinase C (PK-C) ligands with low-namomolar binding affinities by constructing diacylglycerol (DAG) mimetics in which the sn-2 carbonyl of DAG was constrained into a lactone ring. An additional structural element that helped achieve high binding affinity was the presence of branched acyl or alpha-alkylidene chains. In the present study, the effects of similarly branched chains on a different lactone system, where the lactone carbonyl is now equivalent to the sn-1 carbonyl of DAG, are investigated. In this new lactone template, the two chiral centers must have the S-configuration for enzyme recognition. As with the sn-2 DAG lactones, the branched chains were designed to optimize van der Waals contacts with a group of conserved hydrophobic amino acids located on the rim of the C1 domain of PK-C. The acyl and alpha-alkylidene chains were also designed to be lipophilically equivalent (8 carbons each). Eight new compounds (7-14) representing all possible combinations of linear and branched acyl and alpha-alkylidene were synthesized and evaluated. The sn-1 DAG lactones were less effective as PK-C ligands than the sn-2 DAG lactones despite having a similar array of linear or branched acyl and alpha-alkylidene chains

Stereoselective synthesis of CF(2)-substituted phosphothreonine mimetics and their incorporation into peptides using newly developed deprotection procedures

Stereoselective syntheses of all four stereoisomers of CF(2)-substituted nonhydrolyzable phosphothreonine derivatives (33, 39, and their enantiomers) and their incorporation into peptides are described herein. Key to the synthesis of these amino acids was construction of secondary phosphate-mimicking difluoromethylphosphonate units along with generation of two stereocenters. The former was achieved using a Cu(I)-mediated cross-coupling reaction of BrZnCF(2)P(O)(OEt)(2) (8) and beta-iodo-alpha,beta-unsaturated ester 12, with stereochemistry of both alpha- and beta-stereocenters being established using bornane-10,2-sultam as a chiral auxiliary. Diastereoselective hydrogenation of a chiral alpha,beta-unsaturated acylsultam (for the beta-center) (e.g., 16a) and subsequent stereoselective bromination (for the alpha-center of the threo derivative) or amination (for the alpha-center of erythro (allo) derivative) were utilized. Transesterification of the bromide to the benzyl ester followed by azide displacement of the halogen, then reduction of the resulting azide, followed by Boc-protection and finally removal of the benzyl group, afforded protected both L- and D-phosphothreonine mimetics (39 and its enantiomer). On the other hand, protected both L- and D-allo-phosphothreonine mimetics (33 and its enantiomer) were synthesized via transesterification of the above-mentioned amination product, followed by hydrogenolytic removal of the benzyl group. Key to utilization of these amino acid analogues in peptide synthesis was removal of ethyl protection from the difluoromethylphosphonate moiety. A two-step deprotection methodology, consisting of a combination of a first-step reagent [0.3 M BSTFA-TBAI in CH(2)Cl(2), BF(3).Et(2)O] followed by a second-step reagent [1 M TMSOTf-thioanisole in TFA, m-cresol, EDT] was developed for use in solid-phase protocols. A 12-residue Cdc (cell division cycle) 2-peptide 41, possessing two nonhydrolyzable phosphoamino acid mimetics (F(2)Pmab 6 and F(2)Pmp 4), was subjected to this deprotection procedure and was obtained in 25% yield based on the protected resin. The present synthetic method affords nonhydrolyzable phosphoamino acid mimetics-containing peptides in high yield without accompanying side reactions.

Efficient induction of peptide-specific cytotoxic T lymphocytes by LPS-activated spleen cells

Lipopolysaccharides of gram-negative bacteria are potent activators of B cells, dendritic cells and monocytes/macrophages. We have investigated the use of LPS-activated spleen cells as antigen-presenting cells to induce CD8+ cytotoxic T lymphocytes in vivo that are reactive to MHC class I binding peptides. Compared with resting spleen cells, CTL induction was more efficient and less variable for different peptides with LPS-activated spleen cells. Cytotoxic responses were specific for the immunized peptides and contained high affinity CD8+ T cells. The removal of dendritic cells and monocytes/macrophages by Sephadex G10 column did not show profound effects on CTL induction, indicating that B-cell blasts were largely responsible. This easily accessible method should facilitate the screening of MHC class I binding peptides to determine whether or not the host's T-cell repertoire contains reactive T cells.

A new practical strategy for the synthesis of long-chain phosphopeptide

A new practical strategy has been developed for the synthesis of long-chain phosphopeptide. Both the 2-chlorobenzyloxycarbonyl (CIZ) group for Lys and methyl (Me) for phosphoamino acids remained intact, while other commonly used side-chain protecting groups were cleaved quantitatively, during the reaction using a highly acidic trifluoromethanesulfonic acid (TFMSA)-based reagent system (High TFMSA: TFMSA-TFA-m-cresol=1:9:1, v/v). Selective deprotection of the CIZ and Me group-containing protected phosphopeptide resin with the High TFMSA gave a partially protected phosphopeptide fragment suitable for thioester-mediated fragment condensation. A deprotection protocol of the 9-fluorenylmethyloxycarbonyl (Fmoc) group, which evades significant side reaction toward the protected phosphoamino acid, was also developed. These two new findings enabled us to synthesize long-chain phosphopeptide via thioester-mediated fragment condensation.

An automated prediction of MHC class I-binding peptides based on positional scanning with peptide libraries

Specificities of three mouse major histocompatibility complex (MHC) class I molecules, Kb, Db, and Ld, were analyzed by positional scanning using combinatorial peptide libraries. The result of the analysis was used to create a scoring program to predict MHC-binding peptides in proteins. The capacity of the scoring was then challenged with a number of peptides by comparing the prediction with the experimental binding. The score and the experimental binding exhibited a linear correlation but with substantial deviations of data points. Statistically, for approximately 80% of randomly chosen peptides, MHC-binding capacity could be predicted within one log concentration of peptides for a half-maximal binding. Known cytotoxic T-lymphocyte epitope peptides could be predicted, with a few exceptions. In addition, frequent findings of MHC-binding peptides with incomplete or no anchor amino acid(s) suggested a substantial bias introduced by natural antigen processing in peptide selection by MHC class I molecules.

Treatment of renovascular hypertension using stent implantation in an elderly patient with NIDDM

A 70-year-old man with NIDDM was diagnosed as having renovascular hypertension (RVH), based on a stenosis of the ostial portion of the left renal artery with markedly elevated plasma renin activity (PRA) in both the left renal vein and the peripheral blood, and positive captopril tests. After percutaneous transluminal renal angioplasty (PTRA), his blood pressure (BP) and PRA normalized. However, since restenosis occurred three months later, stent therapy was applied, and consequently BP and PRA normalized immediately after this procedure. During the one-year follow-up, side effects have not been noted. We propose that stent therapy may be feasible for ostial renal artery stenosis in elderly diabetic patients.

Inhibitory mechanism of the CXCR4 antagonist T22 against human immunodeficiency virus type 1 infection

We recently reported that a cationic peptide, T22 ([Tyr(5,12), Lys(7)]-polyphemusin II), specifically inhibits human immunodeficiency virus type 1 (HIV-1) infection mediated by CXCR4 (T. Murakami et al., J. Exp. Med. 186:1389-1393, 1997). Here we demonstrate that T22 effectively inhibits replication of T-tropic HIV-1, including primary isolates, but not of non-T-tropic strains. By using a panel of chimeric viruses between T- and M-tropic HIV-1 strains, viral determinants for T22 susceptibility were mapped to the V3 loop region of gp120. T22 bound to CXCR4 and interfered with stromal-cell-derived factor-1alpha-CXCR4 interactions in a competitive manner. Blocking of anti-CXCR4 monoclonal antibodies by T22 suggested that the peptide interacts with the N terminus and two of the extracellular loops of CXCR4. Furthermore, the inhibition of cell-cell fusion in cells expressing CXCR4/CXCR2 chimeric receptors suggested that determinants for sensitivity of CXCR4 to T22 include the three extracellular loops of the coreceptor.

Marked increase in anti-HIV activity, as well as inhibitory activity against HIV entry mediated by CXCR4, linked to enhancement of the binding ability of tachyplesin analogs to CXCR4

T22 ([Tyr5,12, Lys7]-polyphemusin II) is a strong anti-HIV compound. Six analogs of T22 and two natural forms were synthesized. Of them, all downsized peptides (14 residues; TW70, T131, T134, and T140) showed a higher selectivity index than did other, 17- or 18-residue peptides. In particular, T134 and T140 showed both lower cytotoxicity and higher antiviral activity than did T22 against HIV infection of MT-4 cells, an HTLV-I-bearing T cell line. To clarify the inhibitory mode of T22 and its analogs, we used a single-round replication assay (luciferase assay), in which different envelope-bearing pseudotypes were used to infect CXCR4- or CCR5-bearing U87 cells via CD4. All of the analogs inhibited T cell line-tropic strain HXB-2 (X4) and dual-tropic strain 89.6 (R5X4) HIV infections mediated by CXCR4, but had no effect on macrophage-tropic strain ADA (R5) or 89.6 HIV infections mediated by CCR5. The inhibition by T134 (IC50 of 2.70 nM) and T140 (IC50 of 0.432 nM) was also stronger than that by T22 (IC50 of 5.05 nM). The binding of anti-CXCR4 monoclonal antibody 12G5 to lymphoma-derived T cell line Sup-T1 was more efficiently blocked by T134 and T140 than by T22. Taken together, T22 and its analogs T134 and T140 exerted their inhibition by specific binding to CXCR4. The marked increase in the anti-HIV activity of T134 and T140 was ascribed to an enhancement in their ability to bind to CXCR4.

T134, a small-molecule CXCR4 inhibitor, has no cross-drug resistance with AMD3100, a CXCR4 antagonist with a different structure

T22, an analog of polyphemusin II (18 amino acid residues), was found to block T-tropic human immunodeficiency virus type 1 (HIV-1) entry into target cells as a CXCR4 inhibitor. We synthesized T134, a small analog (14 amino acid residues) of T22 with reduced positive charges. T134 exhibited highly potent activity and significantly less cytotoxicity in comparison to that of T22. T134 prevents the anti-CXCR4 monoclonal antibody from binding to peripheral blood mononuclear cells but has no effect on the binding of anti-CCR5 monoclonal antibodies. Since T134 inhibits the binding of stromal cell-derived factor-1 (SDF-1) to MT-4 cells, it seems that T134 prevents HIV-1 entry by binding to CXCR4. The bicyclam AMD3100 has also been shown to block HIV-1 entry via CXCR4 but not via CCR5. Both T134 and AMD3100 are CXCR4 antagonists and low-molecular-weight compounds but have different structures. Our results indicate that T134 is active against wild-type T-tropic HIV-1 strains and against AMD3100-resistant strains.

A low-molecular-weight inhibitor against the chemokine receptor CXCR4: a strong anti-HIV peptide T140

T22 ([Tyr5,12, Lys7]-polyphemusin II) is an 18-residue peptide amide, which has strong anti-HIV activity. T22 inhibits the T cell line-tropic (T-tropic) HIV-1 infection through its specific binding to a chemokine receptor CXCR4, which serves as a coreceptor for the entry of T-tropic HIV-1 strains. Herein, we report our finding of novel 14-residue CXCR4 inhibitors, T134 and T140, on the basis of the T22 structure. In the assays we examined, T140 showed the highest inhibitory activity against HIV-1 entry and the strongest inhibitory effect on the binding of an anti-CXCR4 monoclonal antibody (12G5) to CXCR4 among all the CXCR4 inhibitors that have been reported up to now.

Induction of cross-reactivity in an endogenous viral peptide non-reactive to FBL-3 tumor-specific helper T-cell clones

We previously reported a helper T-cell (Th) epitope (peptide i) which corresponded to the sequence ranging from positions 462 to 479 from the N-terminus of the Friend-murine leukemia virus (F-MuLV) envelope protein (env462-479). Homologous sequences exist in both Moloney-murine leukemia (M-MuLV env452-469) and endogenous AKV (AKV env453-470) viruses, which differ from F-MuLV env462-479 in 5 and 7 amino acids, respectively. However, peptide i-specific Th clones did not respond to either of the corresponding exogenous or endogenous peptides. One amino acid substitution in M-MuLV env452-469 (Asn to Tyr at position 465: N465Y) and three amino acids in AKV env453-470 (H460S, A466Y and Y468H) endowed both peptides with the reactivity to one of the Th clones, F5-5, almost to the same degree as peptide i. However, the other Th clones responded differently to each of the modified endogenous peptides substituted by one to three amino acids. The cells responsive to the cross-reactive peptides occupied only a minor portion, if any, of the bulk cultured lymph node cells from peptide i-immune mice, and in particular, no significant response to the modified endogenous peptides was observed in repeated experiments. The exchange of at least 3 residues was necessary for the endogenous peptide to acquire sufficient cross-reactivity to two of the three Th clones. However, it was noticeable that a single substitution of alanine by tyrosine at the dominant T-cell receptor (TCR) contact position of the peptide i(e) generated a weak but significant cross-reactivity to one of the three Th clones in this study. Thus, peptides of endogenous retroviral origin that would be modified by mutational events might become 'non-self' and prime Th cells leading to auto-antibody production and resulting in autoimmune disease.

Pharmacophore identification of a chemokine receptor (CXCR4) antagonist, T22 ([Tyr(5,12),Lys7]-polyphemusin II), which specifically blocks T cell-line-tropic HIV-1 infection

We have previously found that T22 ([Tyr(5,12), Lys7]-polyphemusin II) has strong anti-human immunodeficiency virus (HIV) activity, and that T22 inhibits T cell-line-tropic HIV-1 infection mediated by CXCR4/fusin. T22 is an 18-residue peptide amide, which takes an antiparallel beta-sheet structure that is maintained by two disulfide bridges. Structure-activity relationship (SAR) studies on T22 have disclosed the contributions of each region of T22 to activity or cytotoxicity, and have provided the following useful information to develop new CXCR4 antagonists: The number of Arg residues in the N-terminal and C-terminal regions of T22 is closely related to anti-HIV activity. Addition of a variety of functional groups at the N-terminal end results in increases in activity. Disulfide rings, especially the major disulfide loop, are indispensable for anti-HIV activity and maintenance of the beta-sheet structure. Trp3 can be replaced by other aromatic residues (Tyr, Phe and L-2-naphthylalanine). Between two repeats of Tyr-Arg-Lys, which are a characteristic structure in T22, Tyr-Arg-Lys in the N-terminal portion is more closely associated with anti-HIV activity and maintenance of the beta-sheet structure. A positive charge in the side chain at the (i + 1) position of the beta-turn region is necessary for strong activity. Through these studies, we have found several compounds having higher selectivity indexes (50% cytotoxic concentration/50% effective concentration) than that of T22.

Single photon emission CT images in a case of intraventricular neurocytoma

Although Tc-99m HMPAO uptakes in various brain tumors have been reported, SPECT images of neurocytoma have not been described. The authors report a patient with intraventricular neurocytoma (IN) who demonstrated significant uptake of Tc-99m HMPAO and Tl-201 Cl before brain biopsy. Residual tumor after biopsy showed significant uptake of I-123 IMP on early SPECT images, but this uptake was decreased on delayed images. The three radionuclides seem to have different uptake mechanisms.

Overlapping epitopes of friend murine leukemia virus gag-encoded leader sequence recognized by single cytotoxic T-lymphocyte clones

The leader signal sequence of the non-structural gag-encoded glycoprotein precursor, Pr75gag, of Friend murine leukemia virus (F-MuLV) contains overlapping epitopes, SIVLCCLCL (p71-79) and CCLCLTVFL (p75 83) that activate Friend virus (FV)-induced tumor (FBL-3)-specific cytotoxic T-lymphocytes (CTL) (Kondo et al., J. Virol., 69, 1995, 6735-6741; Chen et al., J. Virol., 70, 1996, 7773-7782). It was investigated whether these two peptides are recognized by a single CTL clone or by individual clones with different specificities. The results show that both hydrophobic and cysteine-containing peptides are bound to H-2Db class I major histocompatibility complex (MHC) molecules and cross-recognized by a single CTL clone as well as bulk-cultured CTL from the spleens of mice immunized with FBL-3. The peptide p71-79 was effective for sensitizing target cells to lysis by CTL in the concentration of common antigenic peptides. Moreover, peptide p75-83 was 1000-fold more potent than the peptide p71-79. Specific cytotoxicity assays with variant peptides with alanine- and serine-substitutions suggested a highly complex function of the disulfide bond-forming peptides potentially sensitive to small sequence differences. The dominance of CTL responses to the transmembrane region is discussed in light of the high affinity of a novel hydrophobic peptide to compete with other peptides for binding to MHC molecules.

Downsizing of an HIV-cell fusion inhibitor, T22 ([Tyr5,12, Lys7]-polyphemusin II), with the maintenance of anti-HIV activity and solution structure

T22 ([Tyr5,12,Lys7]-polyphemusin II) has been shown to have strong anti-human immunodeficiency virus (HIV) activity comparable to that of 3'-azido-2',3'-dideoxythymidine (AZT). T22, an 18-residue peptide amide, takes an antiparallel beta-sheet structure that is maintained by two disulfide bridges. Herein we synthesized several shortened analogs of T22 in order to search for a more suitable lead compound. A 14-residue analog having one disulfide bridge, TW70 (des-[Cys8,13, Tyr9,12]-[D-Lys10, Pro11]-T22), was found to have highly potent activity comparable to that of T22, and to take an antiparallel beta-sheet structure similar to that of T22. This indicates that the molecular size of T22 can be reduced without loss of activity or significant change in the secondary structure, and that TW70 may represent a novel lead compound. Furthermore, modifying the N-terminal alpha-amino group of TW70 with a fluoresceinthiocarbamoyl group, and the epsilon-amino group of D-Lys8 at the turn portion with a 5-aminopentanoyl group remarkably increased the selectivity index (50% cytotoxic concentration/50% effective concentration).

Effective lowly cytotoxic analogs of an HIV-cell fusion inhibitor, T22 ([Tyr5,12, Lys7]-polyphemusin II)

A tachyplesin peptide analog, T22 ([Tyr5,12, Lys7]-polyphemusin II), and its shortened congener, TW70 (des-[Cys8,13, Tyr9,12]-[D-Lys10, Pro11]-T22) have strong anti-human immunodeficiency virus (HIV) activity, comparable to that of 3'-azido-2', 3'-dideoxythymidine (AZT). T22 and TW70 are extremely basic peptides, containing 5 Arg residues and 3 Lys residues. The number of positive charges might be related in part to high collateral cytotoxicities of T22 and TW70. Here we have synthesized several analogs, in which the number of positive charges has been reduced through amino acid substitutions using Glu or L-citrulline. As a result, several effective compounds have been found which possess higher selectivity indexes (SIs, 50% cytotoxic concentration/50% effective concentration) than those of T22 and TW70. Higher SIs were attributed mainly to a decrease in cytotoxicity.

A small molecule CXCR4 inhibitor that blocks T cell line-tropic HIV-1 infection

Several members of the chemokine receptor family have been shown to function in association with CD4 to permit human immunodeficiency virus type 1 (HIV-1) entry and infection. The CXC chemokine receptor CXCR4/fusin is a receptor for pre-B cell growth stimulating factor (PBSF)/stromal cell-derived factor 1 (SDF-1) and serves as a coreceptor for the entry of T cell line-tropic HIV-1 strains. Thus, the development of CXCR4 antagonists or agonists may be useful in the treatment of HIV-1 infection. T22 ([Tyr5,12,Lys7]-polyphemusin II) is a synthesized peptide that consists of 18 amino acid residues and an analogue of polyphemusin II isolated from the hemocyte debris of American horseshoe crabs (Limulus polyphemus). T22 was found to specifically inhibit the ability of T cell line-tropic HIV-1 to induce cell fusion and infect the cell lines transfected with CXCR4 and CD4 or peripheral blood mononuclear cells. In addition, T22 inhibited Ca2+ mobilization induced by pre-B cell growth stimulating factor (PBSF)/SDF-1 stimulation through CXCR4. Thus, T22 is a small molecule CXCR4 inhibitor that blocks T cell line-tropic HIV-1 entry into target cells.

[Radiation therapy for advanced gastric cancer]

Thirteen patients with advanced gastric cancer treated by palliative radiotherapy were retrospectively analyzed. The radiation sites were abdominal cavities in 8 cases, superficial masses in 5 and lung metastasis in one. The purposes were to diminish mass size in 5 cases, to relieve pain in 3 and to reduce stenosis in 6. The total doses were more than 40 Gy in 10 patients. In 2 cases, the intracavitary irradiation was performed using 192Ir. In one case, radiation had to be stopped at the dose of 22.5 Gy because of poor general condition. Partial response was obtained in 6 of 12 cases (RP, 50%). The sites of responders were superficial lesions in 4 and hepatic hilar mass in 2, which were given intracavitary as well as external radiation. Pain relief was achieved in all patients suffering from it. One of 3 cases with esophageal stenosis showed marked improvement in swallowing. Two patients showed a decrease in the levels of tumor markers. Five patients had side effects of more than grade 2. Two of them were grade 3, one thrombocytopenia and one diarrhea. The median survival time of all cases was 9 months, and 5 patients could shift to home care. These results suggest that palliative radiotherapy could be one of the most useful locoregional therapies for advanced gastric cancer, in the aspect of improvement of patient's QOL.

[Efficiency of segmental SMANCS/Lip-TAE for hepatocellular carcinoma--comparative studies in the efficacy of segmental SMANCS/Lip-TAI]

We compared the segmental SMANCS/Lip-TAI and the segmental SMANCS/Lip-TAE and studied the effectiveness of both treatments and the influence and/or the side effects on liver function. In resected cases, we studied histopathologic examination. The response rate of the group treated by TAI was 28.6%, and that of the group treated by TAE was 76.5%. In the group treated by TAE, the therapeutic effects were good in nodular type HCC, using small doses of SMANCS. In both groups, the incidence and degree of side effects showed no significant difference. Hepatic insufficiency occurred in a few cases of the group treated by TAI. In resected cases, viable areas remained below the tumor capsule. In conclusion, segmental SMANCS/Lip-TAE seemed to be an effective treatment without any serious complications.

An anti-HIV peptide, T22, forms a highly active complex with Zn(II)

T22 ([Tyr5,12, Lys7]-polyphemusin II) has been shown to have strong anti-human immunodeficiency virus (HIV) activity, comparable to that of 3'-azide-2', 3'-dideoxythymidine (AZT). T22 takes an antiparallel beta-sheet structure maintained by two disulfide bridges and contains two antiparallel repeats of Cys-Tyr-Arg-Lys-Cys. As reported herein, fully reduced T22 was found by HPLC and ion spray mass spectrometric analyses to form a complex in a molar ratio of 1:1 with Zn(II) ion at neutral pH in aqueous solution. Complexation of Zn(II) ion to this peptide appears to result in tetracoordinate bonding to sulfur atoms of four Cys residues. We also found that the anti-HIV activity of the T22-Zn(II) complex was fourfold stronger than that of T22.

Analysis of the interaction of an anti-HIV peptide, T22 ([Tyr5, 12, Lys7]-polyphemusin II), with gp120 and CD4 by surface plasmon resonance

We have previously found that T22 ([Tyr5, 12, Lys7]-polyphemusin II) exhibits strong anti-human immunodeficiency virus (HIV) activity comparable to that of 3'-azido-2', 3'-dideoxythymidine (AZT). The inhibition mechanism of T22 on HIV-replication has not been elucidated precisely yet, and hence the target molecules of T22 have not been identified. However, our recent research suggested that T22 exerts its effect by blocking virus-cell fusion at an early stage of HIV infection and that T22 might interact with an HIV envelope protein and/or a T-cell surface protein, both of which are critical for HIV infection. In this paper we demonstrated that T22 binds specifically to both gp120 (an envelope protein of HIV) and CD4 (a T-cell surface protein) and that both bindings can be inhibited by an anti-T22 antibody, using biosensor technology (BIAcoreTM) based on the principles of surface plasmon resonance. Linearization by the BIAcoreTM system (BIAlogue software) and nonlinear least squares analysis by curve fitting with exponential equations showed that both interactions have close dissociation constants (approximately 10(-7) M). The present study suggests that T22 inhibits the virus-cell fusion process through binding to both gp120 and CD4.

Interaction of an anti-HIV peptide, T22, with gp120 and CD4

T22 ([Tyr5,12, Lys7]-polyphemusin II) has been shown to have strong anti-human immunodeficiency virus (HIV) activity. The precise mechanism of action of T22 on HIV-replication has not been elucidated yet, nor have the targets of T22 been identified. However, our previous research suggested that T22 exerts its effect by blocking virus-cell fusion and that T22 might interact with an HIV envelope protein and/or a T-cell surface protein. Herein we use a novel biosensor based on the principles of surface plasmon resonance (BIAcore) to demonstrate that T22 binds specifically to both gp120 (an envelope protein of HIV) and CD4 (a T-cell surface protein) and that both bindings can be inhibited by an anti-T22 antibody. The data obtained suggest that T22 inhibits virus-cell fusion through the double binding to the above two proteins.

A single retroviral gag precursor signal peptide recognized by FBL-3 tumor-specific cytotoxic T lymphocytes

Several dominant T-cell receptors of cytotoxic T-lymphocyte (CTL) clones specific for FBL-3 tumor antigen were clonally amplified in mixed lymphocyte tumor cell cultures derived from an individual immune mouse. Every CTL clone analyzed had a common specificity for a single epitope in the precursor to cell membrane-associated nonstructural gag-encoded protein, Pr75gag, which can be minimally identified by nine amino acid residues, SIVLCCLCL. This epitope is located within the hydrophobic signal sequence motif that mediates translocation of the protein into the endoplasmic reticulum. These novel observations suggest that expression of Pr75gag in FBL-3 tumor cells led to the amplification of CTLs which recognize the signal sequence of the nonstructural gag-encoded glycoprotein precursor.

The synthetic [Tyr5,12,Lys7]-polyphemusin II peptide (T22) binds to the CD4 cell surface molecule

The [Tyr5,12,Lys7]-polyphemusin II peptide (T22) inhibits HIV-1 replication in lymphocytes. The mechanism of T22 inhibition of HIV-1 replication may involve T22 competition with HIV-1 for attachment sites on the plasma membrane of targeted cells. Here we find that the T22 peptide binds to the CD4 molecule in affinity columns. We also find that antiserum to CD4 inhibits cell attachment to T22. Further CD4+ transfected cells attach to T22 while their parental cells which do not express CD4 do not attach to T22. These data demonstrate that T22 binds to the CD4 molecule and supports the hypothesis that T22 inhibits HIV-1 replication by binding to the cell surface CD4 molecule and inhibiting uptake of the virus.

Synthesis of protegrin-related peptides and their antibacterial and anti-human immunodeficiency virus activity

All disulfide analogs (types I, II and III) of protegrin (PG)-1, an 18-residue antimicrobial peptide having two intramolecular disulfide bonds, were synthesized using regioselective disulfide bond formation. Random air-oxidation of the fully reduced PG-1 formed the type III PG-1. In addition, a type III analog containing an amidated carboxy-terminal residue was also prepared. Each analog showed significant and different antibacterial and anti-human immunodeficiency virus (HIV) activity. Deletion of two disulfide bridges caused a significant decrease in activity.

Disulfide bond-forming reaction using a dimethyl sulfoxide/aqueous HCl system and its application to regioselective two disulfide bond formation

Disulfide bond formation in S-acetamidomethyl (Acm) cysteine-containing peptides by successive treatments with silver trifluoromethanesulfonate (AgOTf) and dimethyl sulfoxide (DMSO)/aqueous HCl is described. An S-Acm cysteine was found to be quantitatively converted into cysteine by deprotection of the Acm group with AgOTf followed by DMSO/aqueous HCl treatment. Under these reaction conditions, no significant side reactions were observed with oxidation-sensitive amino acids such as Met, Tyr and Trp. Oxytocin and a Trp-containing peptide, urotensin II, were prepared by this method. Furthermore, regioselective two disulfide bond formation was found to be feasible by the combination of air oxidation and the AgOTf-DMSO/HCl system. This strategy has been successfully applied to the syntheses of tachyplesin I and endothelin I, which have two disulfide bonds and a Trp residue in the molecule.