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1.

001-es BibID:BIBFORM033900
035-os BibID:PMID:8251954 WOS:A1993MB41500002
Első szerző:Halmos Gábor (gyógyszerész, receptorfarmakológus, experimentális onkológus)
Cím:Use of radioreceptor assay and cell superfusion system for in vitro screening of analogs of growth hormone-releasing hormone / Gabor Halmos, Zoltan Rekasi, Balazs Szoke, Andrew V. Schally
Dátum:1993
Megjegyzések:In the search for more active agonists and antagonists of human growth hormone-releasing hormone (hGH-RH), various analogs are being synthesized. In order to follow the binding affinity of these analogs, we have developed a sensitive in vitro radioreceptor assay for GH-RH based on binding of labeled [His1,Nle27]hGH-RH(1-32)NH2 to rat anterior pituitary membrane homogenates by adapting and modifying earlier methods. Scatchard analysis of saturation binding data demonstrated the presence of a single class of specific binding sites for GH-RH in membranes of rat anterior pituitaries with a Bmax of 33.3 +/- 5.2 fmol/mg protein and an apparent Kd of 0.19 +/- 0.02 nM. In displacement analyses, we compared the binding affinity of [His1,Nle27]hGH-RH(1-32)NH2 with its iodinated derivative. No significant differences were detected in IC50 concentrations ranging from 0.97 to 3.4 nM between labeled and nonlabeled hGH-RH analogs. These findings demonstrate the validity of the radioreceptor assay. To evaluate the biological activities of hGH-RH derivatives, we applied a sensitive, dispersed rat pituitary cell superfusion system. This dynamic in vitro system eliminates the drawbacks of the static pituitary cell culture. No differences were observed in biological activities of the iodinated and noniodinated hGH-RH analogs. GH-releasing activity obtained from the superfusion assay correlated well with GH-RH receptor binding affinity for all nonlabeled and labeled hGH-RH analogs examined. These two methods are fast, simple, and relatively inexpensive, and provide quantitative data on receptor affinities, biological activities, and hence structure-affinity and structure-activity relationships. Joint use of these two in vitro systems appears to be suitable for screening newly synthesized GH-RH analogs.
Tárgyszavak:Orvostudományok Gyógyszerészeti tudományok idegen nyelvű folyóiratközlemény külföldi lapban
külföldön készült közlemény
Megjelenés:Receptor. - 3 : 2 (1993), p. 87-97. -
További szerzők:Rékási Zoltán Szőke Balázs Schally, Andrew Victor
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2.

001-es BibID:BIBFORM033894
035-os BibID:PMID:7923093 WOS:A1994PK64700016
Első szerző:Halmos Gábor (gyógyszerész, receptorfarmakológus, experimentális onkológus)
Cím:Characterization of bombesin/gastrin-releasing peptide receptors in membranes of MKN45 human gastric cancer / Gabor Halmos, Jacek Pinski, Balazs Szoke, Andrew V. Schally
Dátum:1994
ISSN:0304-3835
Megjegyzések:Binding of the radiolabeled bombesin analog [125I-Tyr4]bombesin to crude cell membranes of MKN45 human gastric cancer grown in nude mice was investigated in vitro. Scatchard analyses of multipoint binding data, performed by complete displacement method demonstrated the presence of two classes of [Tyr4]bombesin binding sites. The high-affinity binding sites had a mean dissociation constant (Kd1) of 2.75 nM with a mean maximal binding capacity (Bmax1) of 492 fmol/mg membrane protein, while the low-affinity binding sites showed a mean dissociation constant (Kd2) of 0.41 microM with a mean maximal binding capacity (Bmax2) of 41.4 pmol/mg membrane protein. Binding of [125(1)-Tyr4]bombesin was specific, reversible and linearly related to the protein concentration of tumor membrane. In displacement studies, the binding of radiolabeled [Tyr4]bombesin was inhibited in a dose-dependent manner by gastrin releasing peptide (GRP)(14-27) and two synthetic antagonists of bombesin/GRP, RC-3095 and RC-3950-II. Both antagonists exhibited high affinity in nearly the same concentration range as GRP(14-27). The presence of receptors for bombesin/GRP on human gastric cancer membranes suggests that bombesin-like peptides may play a role in growth of gastric cancer.
Tárgyszavak:Orvostudományok Gyógyszerészeti tudományok idegen nyelvű folyóiratközlemény külföldi lapban
külföldön készült közlemény
Megjelenés:Cancer Letters. - 85 : 1 (1994), p. 111-118. -
További szerzők:Pinski, Jacek Szőke Balázs Schally, Andrew Victor
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3.

001-es BibID:BIBFORM033893
035-os BibID:PMID:8045917
Első szerző:Qin, Yunfeng
Cím:Bombesin antagonists inhibit in vitro and in vivo growth of human gastric cancer and binding of bombesin to its receptors / Yunfeng Qin, Gabor Halmos, Ren-Zhi Cai, Balazs Szoke, Tibor Ertl, Andrew V. Schally
Dátum:1994
ISSN:0171-5216
Megjegyzések:We investigated the effect of bombesin/gastrin-releasing peptide (GRP) antagonist RC-3095 and other analogs on the growth of Hs746T human gastric cancer cells implanted in nude mice or cultured in vitro and on the binding of bombesin to its receptors. Nude mice bearing xenografts of the Hs746T cell line received s.c. injections of RC-3095 (10 micrograms twice daily) or the vehicle (control) for 21 days. Administration of antagonist RC-3095 inhibited the growth of Hs746T tumors. Treatment with RC-3095 produced a significant decrease in tumor volume, prolonged the tumor volume doubling time from 3.6 days to 5.1 days, and decreased the tumor growth rate by 76.9%. The tumor growth delay time in mice treated with RC-3095 was 2.8 days. Treatment with RC-3095 also decreased the final tumor weight by 88.3% and reduced DNA and protein contents in tumors by 91.5% and 89.5%, respectively, as compared to controls. The presence of specific receptors for bombesin/GRP was investigated on the crude membranes of implanted tumors of Hs746T cells. Saturation binding assays showed that the binding of [125I-Tyr4]bombesin to the membranes was saturable and reversible. Scatchard analysis indicated the presence of a single class of binding sites with a high affinity (Kd = 0.24 +/- 0.07 nM) and a low binding capacity (Bmax = 57.0 +/- 0.9 fmol/mg protein). In displacement studies, the binding of [125I-Tyr4]bombesin was inhibited in a dose-dependent manner by unlabelled bombesin(1-14), [Tyr4]-bombesin and GRP (14-27), but not by structurally unrelated peptides. Synthetic bombesin/GRP antagonists RC-3095, RC-3110, and RC-3950-II were all able to inhibit effectively the binding of [125I-Tyr4]bombesin to the membranes of Hs746T cells. RC-3950-II showed a higher binding affinity for bombesin receptors than RC-3095 or RC-3110. Addition of the non-hydrolyzable guanine-nucleotide analog GTP [S] to the binding buffer caused a significant reduction in the amount of [125I-Tyr4]bombesin bound to the cells, indicating that the bombesin receptor is coupled to a G-protein. In cell cultures, bombesin significantly stimulated the growth of Hs746T cells in vitro as shown by an increase in the uptake of [3H]thymidine. Bombesin antagonist RC-3095 could effectively inhibit the bombesin-stimulated growth of Hs746T cells in cultures. These observations suggest that bombesin/GRP may act as growth factors through specific receptors present on the membranes of Hs746T cells. Bombesin/GRP antagonists appear to nullify the effects of bombesin/GRP and may be useful for the treatment of gastric cancers.
Tárgyszavak:Orvostudományok Gyógyszerészeti tudományok idegen nyelvű folyóiratközlemény külföldi lapban
külföldön készült közlemény
Megjelenés:Journal of Cancer Research And Clinical Oncology. - 120 : 9 (1994), p. 519-528. -
További szerzők:Halmos Gábor (1962-) (gyógyszerész, receptorfarmakológus, experimentális onkológus) Cai, Ren-Zhi Szőke Balázs Ertl Tibor Schally, Andrew Victor
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4.

001-es BibID:BIBFORM033833
035-os BibID:PMID:8879679 WOS:A1996VG04500002
Első szerző:Szepesházi Károly
Cím:Effect of a cytotoxic analog of LH-RH (T-98) on the growth of estrogen-dependent MXT mouse mammary cancers: correlations between growth characteristics and EGF receptor content of tumors / Karoly Szepeshazi, Andrew V. Schally, Gabor Halmos, Balazs Szoke, Kate Groot, Attila Nagy
Dátum:1996
ISSN:0167-6806
Megjegyzések:Female BDF mice bearing estrogen-dependent MXT mouse mammary cancers were treated for 4 weeks with a cytotoxic analog of luteinizing hormone-releasing hormone (LH-RH). T-98 (agonist [D-Lys6]LH-RH linked to glutaryl-2(hydroxymethyl)anthraquinone). The effects of T-98 were compared to those of equimolar amounts of the cytotoxic moiety 2-(hydroxymethyl)anthraquinone hemiglutarate (G-HMAQ) and carrier LH-RH agonist [D-Lys6]LH-RH. Both T-98 and [D-Lys6]LH-RH significantly inhibited the growth of MXT cancers, but G-HMAQ had only a minor non-significant effect. Cytotoxic analog T-98 and the carrier [D-Lys6]LH-RH had similar inhibitory hormonal activities on the pituitary-gonadal axis, but T-98 caused a larger reduction in tumor volume and decreased proliferation characteristics such as mitotic activity and AgNOR numbers in tumor cells to a greater extent than the carrier. Tumor inhibition by T-98, [D-Lys6]LH-RH, and ovariectomy was connected with a significant decrease in binding capacity of EGF receptors in tumor cell membranes. The concentration of EGF receptors remained high in tumors that continued to enlarge in spite of treatment and in all control untreated tumors, even those of small size. Thus, the changes in EGF receptors are likely to be the result of the therapy. Treatment with T-98 caused a greater reduction in the binding capacity of EGF receptors in tumors than [D-Lys6]LH-RH. This could explain the higher inhibitory effect of the cytotoxic analog on tumor growth. Since radiolabeled T-98 was shown to accumulate in MXT cancers 3 hours after a subcutaneous injection, this indicates that specific targeting might play a role in the antitumor effect exerted by this cytotoxic analog.
Tárgyszavak:Orvostudományok Gyógyszerészeti tudományok idegen nyelvű folyóiratközlemény külföldi lapban
külföldön készült közlemény
Megjelenés:Breast Cancer Research And Treatment. - 40 : 2 (1996), p. 129-139. -
További szerzők:Schally, Andrew Victor Halmos Gábor (1962-) (gyógyszerész, receptorfarmakológus, experimentális onkológus) Szőke Balázs Groot, Kate Nagy Attila
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5.

001-es BibID:BIBFORM033898
035-os BibID:(PMID)8008640
Első szerző:Szőke Balázs
Cím:LH-RH analogue carrying a cytotoxic radical is internalized by rat pituitary cells in vitro / Balázs Szőke, Judit Horváth, Gábor Halmos, Zoltán Rékási, Kate Groot, Attila Nagy, Andrew V. Schally
Dátum:1994
ISSN:0196-9781
Megjegyzések:The binding and internalization of a cytotoxic analogue of luteinizing hormone-releasing hormone (LH-RH), T-98 (agonist [D-Lys6]LH-RH linked to glutaryl-2-(hydroxymethyl)anthraquinone), by rat anterior pituitary cells was investigated. Analogue T-98 was bound to pituitary membrane binding sites for LH-RH with a high affinity (Kd = 1.2 nM) and was 17 times more potent in releasing luteinizing hormone (LH) from superfused rat pituitary cells than LH-RH. The labeling of this cytotoxic LH-RH analogue was carried out both with radioactive (125I) and nonradioactive iodine. Monoiodination of the Tyr5 residue of T-98 did not significantly affect its binding affinity but greatly decreased its LH-releasing activity to about 3% of the original value. Di-iodination in the same position lowered binding affinity twenty-threefold and further diminished LH-releasing potency. [125I]T-98 was found to bind very strongly to polystyrene, which precluded the use of regular tissue culture plasticware in our experiments. In pituitary cells cultured in glass vials, binding and internalization of [125I]T-98 were observed, which were time and temperature dependent, and which could be inhibited by excess unlabeled analogue. No enzymatic degradation of labeled T-98 was detected in the culture medium during the incubation. Our results indicate that T-98 is internalized by pituitary gonadotropes through receptor-mediated endocytosis. Because this new class of compounds was designed as anticancer drugs, our findings also suggest that this cytotoxic LH-RH agonist may also be internalized by LH-RH receptors present in breast, prostate, ovarian, and other tumors.
Tárgyszavak:Orvostudományok Gyógyszerészeti tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
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Megjelenés:Peptides. - 15 : 2 (1994), p. 359-366. -
További szerzők:Horváth Judit E. (New Orleans) Halmos Gábor (1962-) (gyógyszerész, receptorfarmakológus, experimentális onkológus) Rékási Zoltán Groot, Kate Nagy Attila Schally, Andrew Victor
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Intézményi repozitóriumban (DEA) tárolt változat
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