RESUMEN
In a human medullary thyroid carcinoma (TT) cell line, expression of the calcitonin (CT)/CT gene-related peptide (CGRP-I) gene (CALC-I or alpha) at the level of mRNA and of encoded peptides is higher than that of the closely related CGRP-II gene (CALC-II or beta). In response to 1 mM dibutyryl cAMP ((Bu)2cAMP), mature CGRP-II mRNA and intact cellular CGRP-II were raised 65- and 10-fold, respectively, at 72 h. Also at 72 h, 1 mM sodium butyrate enhanced CGRP-II mRNA only 9-fold and cellular CGRP-II 2-fold; stimulation of CGRP-I and CT mRNA and of cellular CGRP-I and CT by both (Bu)2cAMP and sodium butyrate was similarly low. During the same incubation time period secreted CGRP-II was raised 44-fold in response to (Bu)2cAMP, and CGRP-I and CT 8- and 42-fold, respectively. In conclusion, gene products of CALC-I (CGRP-I and CT) are present in higher amounts in TT cells than those of CALC-II (CGRP II). Yet (Bu)2cAMP predominantly stimulates the expression of CALC-II.
Asunto(s)
Bucladesina/farmacología , Péptido Relacionado con Gen de Calcitonina/biosíntesis , Calcitonina/biosíntesis , Carcinoma/metabolismo , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Proteínas de Neoplasias/biosíntesis , Neoplasias de la Tiroides/metabolismo , Butiratos/farmacología , Ácido Butírico , Calcitonina/genética , Péptido Relacionado con Gen de Calcitonina/genética , Carcinoma/patología , Dactinomicina/farmacología , Humanos , Proteínas de Neoplasias/genética , Proteínas Proto-Oncogénicas c-myc/biosíntesis , Proteínas Proto-Oncogénicas c-myc/genética , ARN Mensajero/biosíntesis , ARN Neoplásico/biosíntesis , Estimulación Química , Neoplasias de la Tiroides/patología , Células Tumorales Cultivadas/efectos de los fármacosRESUMEN
We examined whether the macrophages in the liver, Kupffer cells, could be activated to a tumoricidal state in a similar way as has been described for other macrophage types. Kupffer cells were isolated by centrifugal elutriation of pronase-treated rat livers. Incubation with highly purified recombinant rat gamma-interferon in combination with small amounts of lipopolysaccharide or muramyldipeptide resulted in highly cytotoxic macrophages, as measured against P815 tumor cells in an 18 h 51Cr-release assay. Incubation of Kupffer cells with the stimulators entrapped within liposomes, caused phagocytosis of the liposomes and subsequent activation to tumor cytotoxicity, provided that both rat gamma-interferon and subthreshold doses of either lipopolysaccharide or muramyldipeptide were encapsulated. The minimum amount of liposomal rat gamma-interferon that induced optimal activation was 0.5 U/ml, while 6 ng/ml of liposomal lipopolysaccharide or muramyldipeptide was required. Cytotoxicity of Kupffer cells activated in this way, persisted for at least 48 h. Since liposomes in circulation are readily cleared by the liver macrophages, these findings may have therapeutic implications.
Asunto(s)
Acetilmuramil-Alanil-Isoglutamina , Interferón gamma/uso terapéutico , Macrófagos del Hígado/efectos de los fármacos , Lipopolisacáridos , Liposomas/administración & dosificación , Hígado/citología , Proteínas Recombinantes/uso terapéutico , Animales , Citotoxicidad Inmunológica/efectos de los fármacos , Femenino , Interferón gamma/administración & dosificación , Macrófagos del Hígado/inmunología , Ratones , Ratones Endogámicos C57BL , Metástasis de la Neoplasia , RatasRESUMEN
The preparation of 99mTc(Sn)HMDP was investigated as a function of pH, Sn(II) and ligand concentration. HMDP could be labeled efficiently from pH 2-9. The Sn(II) and the ligand concentrations had a beneficial influence. The composition of the radiopharmaceutical under various experimental conditions was studied by means of gel chromatography on Biogel P-4. Six different complexes were found. A preparation consisted of maximally three major complexes. The presence of a particular complex was mainly determined by pH and ligand concentration. The Sn(II) concentration had little influence.