摘要:

AbstractAvian progesterone receptor exists as two forms, A and B, with molecular weights of 79,000 and 110,000 daltons, respectively. The origin and significance of these two forms is an area of active investigation and debate. Monoclonal antibodies produced against these two forms were used to examine receptor stability in cytosol and changes in the receptor forms induced by hormone binding.The lability of hormone binding at elevated temperatures is well documented. Analysis by Western blotting showed the receptor was stable in freshly prepared oviduct cytosol for 2 hr at 37°C, while hormone binding was lost within 30 min. However, loss of receptor through degradation was seen when cytosol was prepared from frozen tissue or when homogenization was excessive.Progesterone was injected into diethylstilbestrol‐stimulated chicks to examine, in vivo, effects of hormone treatment on receptor forms in the cytosol and nuclear fractions. Progesterone treatment caused a time‐ and dose‐dependent conversion of the A receptor to a form (A′) with a slower electrophoretic mobility. The cytosolic progesterone receptor was divided equally between the B and A forms, while the nuclear receptor was predominantly A′. The amount of nuclear receptor was consistently less than cytosolic receptor. Receptor phosphorylation was analyzed by incubating tissue minces with [32P]orthophosphate with or without progesterone followed by immune isolation of receptor forms. Progesterone treatment caused a time‐dependent increase in cytosol receptor phosphorylation which was evident after 5 min of treatment. This phosphorylation was observed with both the A and B receptor forms. The results indicate that receptor phosphorylation is a very early event during progest

ISSN:0730-2312    

DOI:10.1002/jcb.240360202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractMessenger RNA expression of a human endogenous provirus, ERV3, has been characterized in 170 specimens of normal and malignant human tissues and cells. In contrast to the high expression in first‐trimester and full‐term placental chorionic villi, most other human tissues expressed ERV3 mRNAs at a level of 2–30% of placenta. However, ERV3 mRNAs were not detected in choriocarcinoma tumor cell lines. These studies suggest that the ERV3 provirus may have been preempted for a biological function and disruption of its mRNA expression results in choriocarc

ISSN:0730-2312    

DOI:10.1002/jcb.240360203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThis study describes a differential frequency of spontaneous fusion between metastatic and nonmetastatic subpopulations derived from a single mouse mammary tumor. Subpopulations 66, 66cl4 (a variant of 66 which is resistant to both thioguanine and ouabain), 410.4, and 44FTO (a thioguanine‐resistant, ouabain‐resistant derivative of 410.4) spontaneously metastasize from subcutaneous and mammary fatpad sites. Subpopulations 168, 168FARO (a diaminopurine‐resistant, ouabain‐resistant derivative of 168), 67, 68H, and 410 do not. The ability of these subpopulation lines to fuse spontaneously in vitro was determined after coculturing a drug‐resistant line with a wild‐type line in nonselective media. After 16–20 h of coculture, cells were plated in the appropriate media to select for fusion products—either HAT (hypoxanthine, aminopterin, thymidine) plus ouabain or AA (alanosine, adenine) plus ouabain—to determine the number of colony‐forming cells (fusion products) present per 104cells plated. When both subpopulations of the pair in the fusion mixture were metastatic, a significantly greater number of fusion products was recovered than if one or both of the subpopulations in the fusion mixture was nonmetastatic, with one exception: line 410 readily fused with both 66cl4 and 44FTO. Subline 410 was highly metastatic when originally isolated but lost its metastatic competence after a brief tim

ISSN:0730-2312    

DOI:10.1002/jcb.240360204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractHigh‐molecular‐weight genomic DNA isolated from a human cutaneous squamous cell carcinoma (AS) was assayed for its ability to induce tumorigenic transformation of NIH 3T3 cells. Subcutaneous injection of NIH 3T3 cells cotransfected with DNAs from AS tumor and pSV2‐neoplasmid not only induced tumors at the site of injection, but also metastasized spontaneously to the lungs in 100% of nude mice injected. DNA isolated from a representative primary tumor and a metastasis was again used in a second round of transfection. Injection of secondary transfectants into nude mice again resulted in induction of both subcutaneous tumors and spontaneous long metastases. Southern blot hybridization withras‐specific probes revealed that DNA from both primary tumors and metastases induced by AS tumor DNA contained highly amplified Ha‐rasoncogene. Furthermore, DNAs from secondary tumors and metastases induced by DNA from a primary tumor and a metastasis also contained similar highly amplified Ha‐rasoncogene. These results suggest that the amplified Ha‐rasoncogene may be responsible for induction of both tumorigenic and metastatic phenotypes in NIH 3T3 cells transfected with DNA

ISSN:0730-2312    

DOI:10.1002/jcb.240360205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractCytogenetic patterns from primary short‐term culture of breast cancer, renal carcinoma, and tumors of the central nervous system are presented to illustrate the range of karyotypic diversity of human solid tumors as well as their biologic differences in culture systems that support their growth. These studies have illustrated several major issues. (1) Results vary with the tissue of origin: primary cultures from breast are almost uniformly diploid, while renal tumors are near‐diploid, mosaic, and show clonal aberrations; and CNS tumors are heterogeneous: some diploid, some near‐diploid and some highly aneuploid. (2) Results after short‐term culture are selective, representing subpopulations from the heterogeneous cells that are detected on direct analysis of fresh tumors by cytogenetics or flow cytometry (FCM). It is not yet clear whether prognosis depends on the dominant population of the primary tumor or alternatively should be influenced by detection of small aneuploid subpopulations. (3) Evidence from all three tumor types supports the interpretation that cytogenetically normal diploid cells constitute part of some tumor populations, and may be better adapted to routine growth in culture than aneuploid subpopulations from the same primary tumors. These cells may also compose a major portion of the viable population of tumors in vivo and, therefore, could represent a useful model for studies of tumorigenesis and therapeutic r

ISSN:0730-2312    

DOI:10.1002/jcb.240360206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe successful penetration of endothelial basement membranes is an important process in the formation of hematogenous tumor metastases. Heparan sulfate (HS) proteoglycan is a major constituent of endothelial basement membranes, and we have found that HS‐degradative activities of metastatic B16 melanoma sublines correlate with their lung‐colonizing potentials. The melanoma HS‐degrading enzyme is a unique endo‐β‐D‐glucuronidase (heparanase) that cleaves HS at specific intrachain sites and is detectable in a variety of cultured human malignant melanomas. The treatment of B16 melanoma cells with heparanase inhibitors that have few other biological activities, such as N‐acetylated N‐desulfated heparin, results in significant reductions in the numbers of experimental lung metastases in syngeneic mice, indicating that heparanase plays an important role in melanoma metastasis. HS‐degrading endoglycosidases are not tumor‐specific and have been found in several normal tissues and cells. There are at least three types of endo‐β‐D‐glucuronidases based on their substrate specificities. Melanoma heparanase, an Mr∼96,000 enzyme with specificity for β‐D‐glucuronosyl‐N‐acetylglucosaminyl linkages in HS, is different from platelet and mastocytoma endoglucuronidases. Elevated levels of heparanase have been detected in sera from metastatic tumor‐bearing animals and malignant melanoma patients, and a correlation exists between serum heparanase activity and extent of metastases. The results suggest that heparanase is potentia

ISSN:0730-2312    

DOI:10.1002/jcb.240360207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractBinding, endocytosis, and degradation of asialo‐orosomucoid (ASOR) mediated by the galactosyl (Gal) receptor were examined in isolated rat hepatocytes in complete media supplemented with an osmolite. The specific binding of125I‐ASOR to cells at 4°C was unaffected by up to 0.4 M sucrose or NaCl. Unlike sucrose or NaCl, mannitol stimulated125I‐ASOR binding at low concentrations but inhibited binding at higher concentrations. Continuous internalization at 37°C, which requires receptor recycling, was completely blocked at 0.2 M sucrose or 0.15 M NaCl, corresponding in each case to a total osmolality of about 550 mmol/ kg. This effect was reversed and endocytic function was restored by washing the cells, indicating that cell viability was unaffected. The rate of degradation of internalized125I‐ASOR was also inhibited by increasing sucrose concentrations. This inhibition is due to a block in the delivery of ligand to lysosomes and not an effect on degradation per se. In the presence of 0.2 M sucrose, the rate and extent of endocytosis of surface‐bound125I‐ASOR were, respectively, 33.0 ± 8.1% and 69.4 ± 10.5% (n = 8) of the control without sucrose. Under these conditions, the dissociation of internalized receptor‐ASOR complexes was completely inhibited. When sucrose was added, the effect on the endocytosis of surface‐bound125I‐ASOR was virtually immediate. Previous studies showed that about 40% of the surface‐bound125I‐ASOR which is internalized can return to the cell surface still bound to receptor (Weigel and Oka: J Biol Chem 259:1150, 1984). If 0.2 M sucrose was added after endocytosis occurred,125I‐ASOR still returned to the cell surface, although the rate and extent of return were inhibited by more than 50%. Interestingly, hyperosmolarity is the only treatment we have found which can reversibly inhibit, although only partially, the endocytosi

ISSN:0730-2312    

DOI:10.1002/jcb.240360208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractMelanoma growth stimulatory activity (MGSA) is an acid and heat stable, autostimulatory growth factor which was first isolated from culture medium conditioned by the Hs294T human melanoma cell line. In this report, we describe the purification of MGSA from acid ethanol extracts of Hs294T tumors grown in nude mice using a series of Bio‐Gel P30, reverse phase‐high performance liquid chromatography and heparin‐sepharose steps. This modified procedure provides a 10‐fold improved yield of MGSA over previously published procedures. Purified MGSA‐stimulated melanoma cell growth in both3H‐thymidine and cell number assays over a concentration range of 0.06 to 6 ng/ml. The MGSA bioactivity was primarily associated with fractions which exhibited molecular weights of 16 and 13–14 Kd based upon sodium dodecyl sulfate‐polyacrylamide gel electrophoresis. Purified platelet‐derived growth factor (PDGF), insulin‐like growth factor (IGF‐1), transforming growth factor‐beta (TGFβ), and epidermal growth factor (EGF) in combination with TGFβdid not stimulate3H‐thymidine incorporation in Hs294T cells under the conditions used for MGSA bioassay. Monoclonal antibody to MGSA was used to screen melanoma and benign nevus cultures as well as fixed sectioned tissue for MGSA. The majority of the melanoma cultures were MGSA positive, while most nevus cultures were MGSA negative. However, when fixed sectioned tissue was screened for MGSA immunoreactivity, melanoma tissue was MGSA positive and three‐fourths of the benign nevi were MGSA positive. In addition, epidermal keratinocytes and several tissues exhibiting proliferative disorders contained immunoreactive MGSA. These data suggest that MGSA may be a normal regulator of growth and that the microenvironment of the cell may regulate both production

ISSN:0730-2312    

DOI:10.1002/jcb.240360209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0730-2312    

DOI:10.1002/jcb.240360201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY