Phosphorylation and biosynthesis of high molecular weight proteins of tumor nuclear matrix.

Our previous studies showed a predominance of high molecular weight protein group in tumor nuclear matrices. Contrary to normal cells, proteins of this group are preferentially phosphorylated. Phosphoproteins of hepatoma nuclear matrix are selectively subjected to rapid proteolysis. By alkali treatment and a monoclonal antibody against phosphotyrosyl residue the presence of two high molecular weight bands of phosphotyrosyl-containing proteins was detected in nuclear matrices of tumor but not of normal liver cells. High molecular weight protein group of tumor nuclear matrices revealed also a rapid turnover and preferential incorporation of labeled amino acids selectively inhibited by chloramphenicol.

[Characteristics of protein metabolism in labyrinthine tissue]. / Osobennosti belkovogo obmena v tkaniakh ushnogo labirinta.

The synthesis of total protein in organic culture of the internal ear was studied in 16-day embryo of CBA mice exposed to altering factors. The experiments showed feasibility of partial recovery for impaired metabolic processes in the labyrinth following phonophoretic introduction of mitochondrial coenzymes and inhibitors of lysosomal activity. Formation of systemic structural trace by modelling of acoustic stress and verification of protein stress agents was tested making it possible to identify an important component in dysadaption mechanism in mature CBA mice labyrinth.

[Inhibition by antibiotics of the incorporation of labelled amino acids into the nuclear matrix proteins of the Zajdela hepatoma]. / Podavlenie nekotorymi antibiotikami vkliucheniia mechenykh amminokislot v belki iadernogo matriksa gepatomy Zaidelia.

The incorporation of radioactivity into nuclear matrix proteins during incubation of Zajdela hepatoma cells with labelled amino acids was strongly inhibited by chloramphenicol and cycloheximide and slightly inhibited by actinomycin D and mitomycin C. The antibiotics studied inhibited the incorporation of the radioactive label preferentially into proteins with Mr 150 000-220 000, approximately 55 000 and less than 26 000. During incubation of ascites tumour cells with antibiotics, predominantly with chloramphenicol, a decrease in the content of some protein components was observed as well. As in the low molecular weight protein fraction, the intense inhibition of the radioactive label and a decrease of its content was observed, a conclusion is drawn that this protein fraction is characterized by a high turnover rate.

[Selective inhibition by chloramphenicol of protein biosynthesis in ascites tumor cells]. / Izbiratel'noe podavlenie khloramfenikolom biosinteza belkov v kletkakh astsitnykh opukholei.

Chloramphenicol in a dose of 50-200 micrograms/ml sharply inhibits the incorporation of 14C-labelled amino acids into proteins of ascites Zajdela hepatoma cells while it has no effect on protein biosynthesis in rat liver cells. In vivo chloramphenicol selectively inhibits this process in ascites tumour cells of rat Zajdela hepatoma and mouse Ehrlich carcinoma and hepatoma 22a, without inhibiting the process in various organs of tumour-bearing animals. The inhibition of labelled amino acid incorporation into nuclear and especially nuclear matrix proteins is more pronounced than into the whole tissue. A certain degree of inhibition was revealed in liver cells as well.

[Inhibition by cycloheximide of the incorporation of radioactive amino acids into nuclear matrix proteins of Zajdela ascites hepatoma]. / Ingibirovanie tsiklogeksimidom vkliucheniia radioaktivnykh aninokislot v belki iadernogo matriksa astsitnoi gepatomy Zaidela.

Proteins of nuclear matrix readily incorporated labelled amino acids after incubation of ascites Zajdela hepatoma cells with 14C-hydrolyzate of chlorella proteins. Cycloheximide at the concentrations, inhibiting the cytoplasmic protein synthesizing system, significantly decreased the labelled amino acid incorporation both into nuclear proteins and into proteins of nuclear matrix but the antibiotic effect was less distinct in the matrix. The incorporation into proteins with molecular mass below 26 KD and above 150 KD was especially distinctly inhibited as shown in experiments on separation of the matrix proteins by means of SDS-polyacrylamide gel electrophoresis. Besides the inhibition of the incorporation of amino acids, a decrease in content was found in studies of the fraction of matrix low molecular proteins. The high rate of metabolism of nuclear matrix low molecular proteins is discussed.