A SOMATOSTATIN ANALOG INDUCES TRANSLOCATION OF KU-86 AUTOANTIGEN FROMTHE CYTOSOL TO THE NUCLEUS IN COLON-TUMOR CELLS

Flow cytometric and electron microscopic immunocytochemical studies ha ve been performed in HT-29 human colon tumour cells in vitro, to deter mine and localise p86 Ku protein, which is a regulatory subunit of DNA -dependent kinase and a specific binding site for somatostatin. We hav e demonstrated that HT-29 cells contain p86 Ku and that the distributi on between the cytoplasm and the nucleus is even. After administration of the somatostatin analogues Sandostatin and TT-232 to MT-29 cells, the p86 Ku content of the cytoplasmic compartment decreased in the fir st 4 h. An increase in the content of this protein in the nuclear comp artment was observed at hour 1 followed by a decrease at hour 4 after treatment. Quantitative differences between the two analogues have bee n observed in this respect. The practical significance of these findin gs is discussed. (C) 1998 Elsevier Science Inc.