RESUMEN
We identified an NH2-terminally truncated HER-2/neu product of M(r) 95,000 with in vitro kinase activity by Western blotting and immunoprecipitations using domain-specific antibodies. p95 levels correlated with the extracellular domain (ECD) shed from different cells under varied conditions. Both ECD and p95 were at approximately 20-fold lower levels in SKOV3 ovarian carcinoma cells, as compared to BT474 breast carcinoma cells. Both were stimulated by treatment of cells with the phorbol ester tumor promoter phorbol 12-myristate 13-acetate and the lysosomotrophic agent chloroquine. The hydroxamate inhibitor of metalloproteases, TAPI, suppressed both p95 and ECD in a dose-dependent fashion, with maximal inhibition at < or = 10 microM in BT474 cells. Cancer tissues were analyzed by Western blotting and scored for p95HER-2/neu and for p185HER-2/neu expression. Breast and ovarian cancer tissues were both found to express p95HER-2/neu in addition to p185HER-2/neu. Of 161 breast cancer tissues, 22.4% expressed p95, 21.7% overexpressed p185, and 14.3% were p95 positive and overexpressed p185. A higher proportion of node-positive patients (23 of 78) than node-negative patients (9 of 63) expressed p95 in all tumors combined (P = 0.032). In the group that overexpressed p185, those that contained p95 were associated with node-positive patients (15 of 21), whereas those that were p95 negative were associated with node-negative patients (8 of 11; P = 0.017). Neither p95- nor p185-rich patients significantly correlated with tumor size or with hormone receptor status in this study. Our findings show that breast cancers, which express the HER-2/neu oncogene, are heterogeneous with respect to HER-2/neu protein products. p95HER-2/neu appears to distinguish tumors that have metastasized to the lymph nodes from those in node-negative patients.
Asunto(s)
Neoplasias de la Mama/metabolismo , Proteínas de Neoplasias/química , Receptor ErbB-2/química , Células 3T3 , Animales , Neoplasias de la Mama/química , Neoplasias de la Mama/patología , Dipéptidos/farmacología , Proteínas de la Matriz Extracelular/metabolismo , Femenino , Humanos , Ácidos Hidroxámicos/farmacología , Metaloendopeptidasas/antagonistas & inhibidores , Ratones , Peso Molecular , Proteínas de Neoplasias/análisis , Fosforilación , Pronóstico , Proteínas Tirosina Quinasas Receptoras/metabolismo , Receptor ErbB-2/análisis , Células Tumorales CultivadasRESUMEN
Although androgens exert major effects on bone remodeling, the mechanisms by which they exert their effects remain unclear. Recently, it has become apparent that receptors for sex steroids may be present in osteoblastic cells. We have examined several cell lines with osteoblastic phenotypes to determine if specific, high affinity androgen receptors are present. Two cell lines of human origin (Saos-2 and U2-OS) and one of rat origin (UMR-106.01) were studied. Androgen binding sites were present in all cell lines. Binding affinities were high (KD = 1.6 - 2.5 x 10(-10) M), and similar to those in classical androgen target tissues (prostate, kidney). Concentrations were greater in the human cell lines (1277 and 1605 sites/cell) than in the rodent line (74 sites/cell). In the human cell lines androgen binding was also specific and typical of androgen receptors in other tissues. Specific estrogen binding was not present in the UMR-106.01 cells, and no estrogen receptors were detectable in the human cell lines using an enzyme-linked receptor immunoassay. Specific binding for progesterone was also absent in the UMR-106.01 cells, but progesterone receptors were detected immunologically in the Saos-2 (119 sites/cell) and U2-OS (118 sites/cell) lines. These findings indicate the presence of androgen receptors that are of similar character to those in classical androgen target tissues, and suggest that the study of these cell lines may be useful in the study of the regulation of androgen effects in osteoblasts.
Asunto(s)
Osteoblastos/citología , Receptores Androgénicos/análisis , Andrógenos/metabolismo , Animales , Células Cultivadas , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Osteoblastos/química , Osteoblastos/ultraestructura , Unión Proteica , Ratas , Receptores Androgénicos/metabolismo , Receptores de Progesterona/análisisAsunto(s)
Prolactina/fisiología , Próstata/crecimiento & desarrollo , Animales , Núcleo Celular/metabolismo , Masculino , Próstata/ultraestructura , Ratas , Ratas Endogámicas , Receptores Androgénicos/metabolismo , Receptores de Superficie Celular/metabolismo , Receptores de Prolactina , Maduración Sexual , Timidina/metabolismoAsunto(s)
Dietilestilbestrol/farmacología , Hígado/metabolismo , Peroxidasas/metabolismo , Receptores de Progesterona/efectos de los fármacos , Útero/metabolismo , Animales , Castración , Citoplasma/metabolismo , Femenino , Hígado/efectos de los fármacos , Ratas , Factores de Tiempo , Útero/efectos de los fármacosRESUMEN
Specific binding sites for 125iodine-prolactin are present in membrane particles obtained from the rat ventral prostate, human benign prostatic hyperplasia and prostatic adenocarcinoma. In the ventral prostate glands of young rats (1 to 4 months old) specific binding of 125iodine-prolactin is higher than in older animals (greater than 8 months old). Subcellular distribution studies revealed that specific 125iodine-prolactin binding activity is associated primarily with the 15,000 and 100,000 g particulate membrane fractions of the rat ventral prostate and human prostate glands. In rats between 2 and 4 months old significant increases in the prolactin binding activity in the 100,000 g membrane fraction of the ventral prostate are observed to occur without concomitant increases in prolactin binding activity in the 15,000 g fraction. The level of specific 125iodine-prolactin binding activity present in the human prostate gland is lower than that observed in the rat ventral prostate gland. Localization of specific prolactin binding sites in the rat ventral psotate and the human prostate gland suggests that prolactin could influence the function of these tissues directly.