amanitins and Carcinoma-256--Walker

The muscle wasting which occurs in animals bearing a transplantable tumour is accompanied by a decrease in the level of protein synthesis and a loss in RNA. This paper examines the behaviour of RNA polymerases I and II (EC 2.7.7.6) in nuclei isolated from skeletal muscle of rats bearing a Walker 256 carcinoma. Marked decreases were observed in template-engaged RNA polymerase I and II activities and in free RNA polymerase I activity. Free RNA polymerase II activity was unaltered. When assays were carried out at high (NH4)2SO4 concentration or in the presence of heparin the diminished RNA polymerase I activity was still apparent, but heparin and high ionic strength overcame the inhibition of RNA polymerase II. Loss of RNA polymerase I activity was associated with a decrease in the number of template-engaged enzyme molecules and in the polynucleotide elongation rate. The number of template-engaged RNA polymerase II molecules was unaltered by tumour growth, but the polynucleotide elongation rate was significantly reduced. No evidence was obtained for any alteration in ribonuclease activity in nuclei or whole muscles of tumour-bearing rats. These results demonstrate an effect of the tumor on transcription in skeletal muscle of its host.

Topics: Amanitins; Animals; Carcinoma 256, Walker; Cell Nucleus; Dactinomycin; Female; Muscles; Rats; Rats, Inbred Strains; Reference Values; Ribonucleases; RNA Polymerase I; RNA Polymerase II; Transcription, Genetic

This study demonstrates a novel feature of PMA, its ability to suppress chemokinetic polarization and locomotion of tumor cells. Walker carcinosarcoma cells exhibit two distinct types of polarization and locomotion, i.e. spontaneous polarization characterized by ruffles at the front and stimulated polarization and locomotion in response to the microtubule-disassembling agents colchicine, vinblastine and nocodazole, which are characterized by blebbing at the front. The tumor promotor phorbol myristate acetate (PMA), but not phorbol, was found to suppress both types of polarization and random locomotion at concentrations between 10(-8) and 10(-6)M. The effect of 10(-6)M PMA was virtually complete within 5 min. Inhibition of locomotion was due to both a reduction in the speed of migrating cells and the proportion of migrating cells. Changes in shape and chemokinesis of Walker carcinosarcoma cells were associated with alterations in the relative amount and the topographical distribution of F-actin as determined by NBD-phallacidin binding. Suppression by PMA was associated with loss of the polar topographical distribution of F-actin visualized by NBD-phallacidin binding. In the presence of PMA, the relative amount of F-actin was higher than in unstimulated controls and lower in cells exposed to microtubule-disassembling agents.

Topics: Actin Cytoskeleton; Actins; Amanitins; Animals; Carcinoma 256, Walker; Cell Adhesion; Cell Movement; Colchicine; Cytoskeleton; Microtubules; Peptides, Cyclic; Phorbols; Rats; Tetradecanoylphorbol Acetate; Vinblastine

Topics: Amanitins; Animals; Carcinoma 256, Walker; Carcinoma, Hepatocellular; DNA; DNA-Directed RNA Polymerases; Kidney; Kinetics; Liver Neoplasms; Magnesium; Manganese; Multiple Myeloma; Neoplasms, Experimental; Organ Specificity; Rats; Sarcoma, Yoshida; Spleen