RESUMEN
Radiolabeled proteins are used in a variety of laboratory applications as well as in radioimmunotherapy. This review focuses on methods that utilize genetic engineering to introduce exogenous phosphorylation sites into proteins. Protein kinase substrate sites can be introduced into target proteins to serve as tags for several purposes. Because many protein kinases, each preferring a unique consensus sequence, are well characterized, the essential structure and function of the target protein can be effectively preserved through judicious selection and design of the phosphate incorporation site. After phosphorylation, these proteins are often indistinguishable from the parent molecules in assays of functional or biological activity. This convenient approach permits incorporation of 32P, 33P, 35S, or nonradioactive 31P, and is rapid, efficient, and safe. Most importantly 32P labeling of monoclonal antibodies or other therapeutic protein candidates has several significant advantages over radioiodination or chemical conjugation of heavy metal isotopes.
Asunto(s)
Anticuerpos Monoclonales/química , Citocinas/química , Inmunoconjugados/química , Marcaje Isotópico/métodos , Mutagénesis Sitio-Dirigida , Radioisótopos de Fósforo/química , Secuencia de Aminoácidos , Animales , Anticuerpos Monoclonales/análisis , Anticuerpos Monoclonales/uso terapéutico , Reacciones Antígeno-Anticuerpo , Bovinos , Niño , Secuencia de Consenso , Citocinas/análisis , Citocinas/uso terapéutico , Humanos , Inmunoconjugados/análisis , Inmunoconjugados/uso terapéutico , Proteínas de la Membrana , Modelos Moleculares , Datos de Secuencia Molecular , Neoplasias/radioterapia , Radioisótopos de Fósforo/análisis , Radioisótopos de Fósforo/uso terapéutico , Fosforilación , Mapeo de Interacción de Proteínas/métodos , Proteínas Quinasas/metabolismo , Procesamiento Proteico-Postraduccional , Proteínas/análisis , Proteínas/química , Proteínas/uso terapéutico , Radioinmunoterapia , Receptor de Interferón alfa y beta , Receptores de Interferón/metabolismo , Proteínas Recombinantes de Fusión/análisis , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/aislamiento & purificación , Proteínas Recombinantes de Fusión/uso terapéutico , Especificidad por Sustrato , Radioisótopos de Azufre/análisis , Radioisótopos de Azufre/química , Radioisótopos de Azufre/uso terapéuticoAsunto(s)
Neoplasias/radioterapia , Oligodesoxirribonucleótidos Antisentido/uso terapéutico , Dosis de Radiación , Radioisótopos/uso terapéutico , Radiofármacos/uso terapéutico , Tionucleótidos/uso terapéutico , Animales , Humanos , Ratones , Radioisótopos de Fósforo/uso terapéutico , Radioisótopos de Azufre/uso terapéuticoRESUMEN
Antisense oligomers may be used as a vehicle for carrying a radiation source into a specific location inside a tumor cell. The effects of radioactive-labeled oligodeoxynucleotides (ODNs) may have both direct antisense inhibition and radiation. Thus far, the use of radioactive ODNs has been limited mostly to clinical biokinetic studies. Therapeutic possibilities remain unknown if the basic question of the optimal source of radiation is unanswered. We have shown previously that oligonucleotide therapy can be effective theoretically with the internally labeled ODN phosphorothioates 32P, 33P, and 35S. Here, we expand the selection of radionuclides; we calculated in vivo subcellular tissue distribution for ODN phosphorothioates using the decay characteristics of several beta- and Auger-emitting radionuclides: 32P, 35S, 51Cr, 67Ga, 111In, (1114m)In, 123I, 125I, 131I, and 201Tl. The absorbed nuclear doses of these radiolabeled oligonucleotides were estimated in different cellular dimensions using the subcellular biodistribution data for two oligonucleotides (ISIS 2105 and ISIS 2922). Our results indicate that Auger-emitter isotopes do not give higher absorbed cell nuclear doses than the isotopes suitable for internal labeling of ODN phosphorothioates. However, the biological difference is difficult to estimate. The best isotope for subcellular targeting was 35S, which gives the smallest variation of nuclear dose in the different cell dimensions we studied (nuclear diameter, 6-16 microm; cellular diameter, 12-20 microm). Therefore, we conclude that in oligonucleotide radiotherapy, nuclear targets should be treated with short-range beta-emitters (35S or 33P) that are suitable for the internal labeling of oligonucleotides unless the relative biological effectiveness of Auger-emitters could be remarkably improved. Dual labeling with 32P and 35S may provide therapeutic benefits when treating smaller and larger targets simultaneously. Further in vivo development, especially with 33P and 35S labels for ODNs, is strongly indicated.
Asunto(s)
Terapia Genética , Oligonucleótidos Antisentido/uso terapéutico , Radioisótopos/uso terapéutico , Radioisótopos de Cromo/uso terapéutico , Radioisótopos de Galio/uso terapéutico , Radioisótopos de Indio/uso terapéutico , Radioisótopos de Yodo/uso terapéutico , Marcaje Isotópico , Modelos Estadísticos , Radioisótopos de Fósforo/uso terapéutico , Dosis de Radiación , Radioisótopos de Azufre/uso terapéutico , Radioisótopos de Talio/uso terapéuticoRESUMEN
Radiolabelled antisense oligodeoxynucleotides have been used for in vivo biokinetic studies in AIDS and cancer patients. The therapeutic possibilities are still unknown and the major question in therapeutic use of radio-oligonucleotide is the optimal source of radiation. We studied the pharmacokinetics and in vivo tissue distribution for oligodeoxynucleotide phosphorothioates by using the data from three different radionuclides: sulphur-35 (t1/2 = 87.4 days, maximum beta-energy = 167 keV), phosphorus-33 (t1/2 = 24.4 days, maximum beta-energy = 250 keV) and phosphorus-32 (t1/2 = 14.3 days, maximum beta-energy = 2270 keV). The absorbed doses of 32P-, 33P- and 35S-labelled oligonucleotides were estimated using the published biodistribution data for several oligonucleotides in two animal models for both tumour xenografts and AIDS. The local energy absorption of 33P turned out to be higher than that of 32P if the mass was smaller than approximately 300 micrograms, and the local absorption of 35S was higher than that of 32P when the mass was <80 micrograms. In a mouse tumour xenograft model an i.v. injected activity seemed to achieve sufficient radiation doses in the tumour: in a 1 g tumour 4.9 Gy for 32P, 5.1 Gy for 33P and 5.5 Gy for 35S were calculated when the kidney dose was kept as 5 Gy. In the same model in smaller tumours the doses were for a 1 mg tumour 0.73 Gy (32P), 5.1 Gy (33P) and 5.5 Gy (35S), and for a 1 microgram tumour 0.08 Gy (32P), 3.1 Gy (33P) and 3.9 Gy (35S). Thus, 33P and 35S have more beneficial radiotherapeutic characteristics than 32P. Relative advantage factors (33P and 35S versus 32P) for kidney and liver doses using these nuclides varied from 0.997 to 1.001 for a 1 g tumour and there was no difference in the radiation dose to normal organs. Therefore, we conclude that in oligonucleotide radiotherapy tumours >1 g should be treated with 32P, whereas smaller tumours should be treated with 33P or 35S. There is no significant difference between 33P and 35S, and either radionuclide could be selected according to labelling properties.
Asunto(s)
Antimetabolitos Antineoplásicos/uso terapéutico , Neoplasias Experimentales/radioterapia , Oligonucleótidos Antisentido/uso terapéutico , Radioisótopos de Fósforo/uso terapéutico , Radioisótopos de Azufre/uso terapéutico , Tionucleótidos/uso terapéutico , Animales , Antimetabolitos Antineoplásicos/farmacocinética , Riñón/metabolismo , Riñón/efectos de la radiación , Hígado/metabolismo , Hígado/efectos de la radiación , Ratones , Neoplasias Experimentales/metabolismo , Oligonucleótidos Antisentido/farmacocinética , Radioisótopos de Fósforo/administración & dosificación , Radioisótopos de Fósforo/farmacocinética , Dosificación Radioterapéutica , Ratas , Radioisótopos de Azufre/administración & dosificación , Radioisótopos de Azufre/farmacocinética , Tionucleótidos/farmacocinética , Distribución TisularRESUMEN
Thiouracil (TU) selectively binds to the pigment melanin during melanogenesis and is rapidly cleared from normal tissues. This compound shows little affinity for pre-formed melanin. BALB/c mice, carrying the subcutaneously transplanted Harding-Passey melanoma, were given i.p. injections of 35S-labeled thiouracil in a range of doses and administration schedules. Injected doses ranged from 1.3 to 10 mCi per mouse with resultant tumor dose rates of 10 to 30 cGy/hr, respectively. At the lower dose rates, growth delay of approximately 1 to 2 weeks was observed in all tumors. At the highest doses used, complete tumor regression (no regrowth) was observed in some cases, with extended growth delays of approximately 6 weeks in the rest. These results illustrate the possible utility of radiolabeled thiouracil as a systemically administered brachytherapy agent for melanoma.
Asunto(s)
Braquiterapia/métodos , Melanoma Experimental/radioterapia , Radioisótopos de Azufre/uso terapéutico , Tiouracilo/farmacocinética , Animales , Melanoma Experimental/metabolismo , Ratones , Ratones Endogámicos BALB CRESUMEN
Described are two methods of evaluation of the uptake of 35S by chondrosarcomas, i.e. autoradiography and external monitoring of the Bremsstrahlung. A higher concentration of sulfur in the tumor area of three patients was demonstrated after the injection of aliquots of both diagnostic and therapeutic activities. Apart from the simple handling and the quickly obtained results, the external monitoring of the Bremsstrahlung permits quantitative evaluation of the degree of uptake and a simple control over the progress of therapy.
Asunto(s)
Condrosarcoma/radioterapia , Radioisótopos de Azufre/uso terapéutico , Autorradiografía , Neoplasias Óseas/radioterapia , Fenómenos Electromagnéticos , Articulación de la Cadera , Humanos , Artropatías/radioterapia , Monitoreo de Radiación/métodos , Radiactividad , Sacro , Neoplasias de los Tejidos Blandos/radioterapia , Neoplasias de la Columna Vertebral/radioterapiaRESUMEN
Measurements were made of the 35S content of tissues obtained from biopsies and autopsies made during and up to 6 months after treatment of chondrosarcoma or chordoma with carrier-free Na235SO4. Usually 70--90% of an intravenous dose was excreted in the urine during the first 3 days. The major component of the blood concentration had a biologic half-time of 0.4--0.7 days. The initial uptakes in chondrosarcoma, chordoma, and red bone marrow were high and nearly equal, but the rates of loss differed greatly. Uptake in epiphyseal cartilage was comparable to that in chondrosarcoma; uptake in other types of cartilage was lower, but subsequent loss was very slow. For an administered dose of 1 mCi per kilogram of body weight, the integrated radiation doses were 2.4 rads for blood, 33 rads for red bone marrow, 155 rads for chondrosarcoma, 49 rads for chordoma, and 135 rads for normal cartilage. Doses to muscle, skin, and fibrous tissue were 7--15 rads.