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Plasma membrane—mediated nuclear uptake and chromatin binding of insulin in tumor cell lines
Author(s) -
RakowiczSzulczynska Ewa M.,
Otwiaska Danuta,
Koprowski Hilary
Publication year - 1990
Publication title -
molecular carcinogenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.254
H-Index - 97
eISSN - 1098-2744
pISSN - 0899-1987
DOI - 10.1002/mc.2940030308
Subject(s) - biology , chromatin , cycloheximide , insulin , cell nucleus , receptor , nucleus , microbiology and biotechnology , dna , biochemistry , protein biosynthesis , endocrinology
Abstract Analysis of different cellular fractions after incubation of SW 948 and SW 707 colorectal carcinoma cells or WM 266‐4 melanoma cells with 125 I‐insulin revealed the nondegraded hormone in the chromatin of these cells. Nuclear 125 1‐insulin was bound to specific fragments of EcoRI‐, Haelll‐, and Hincll‐digested chromatin. A 45‐kDa chromatin protein species that binds 125 I‐insulin was identified. Actinomycin D and cycloheximide inhibited the insulin‐stimulated expression of chromatin receptors. Uptake of 125 I‐insulin by isolated nuclei occurred only in the presence of plasma membranes. Thus, at least some effects of insulin on target cells can be explained by direct gene regulation instead of “second messenger” action.