Translational suppression of syndecan-1 expression in Ha-ras transformed mouse mammary epithelial cells.
A cell surface proteoglycan, syndecan-1, has been shown to participate in the maintenance of the epithelial cell morphology. A point mutated activated c-Ha-ras gene under the control of the glucocorticoid inducible MMTV-LTR promoter was transfected into the mouse mammary epithelial cell line, NOG-8. The NOG-8 ras cells were used to study changes in syndecan-1 expression during epithelial transformation. NOG-8 ras cells, when induced to express Ha-ras, transformed and formed foci in monolayer cultures and colonies in suspension cultures. Expression of syndecan-1 at the cell surface was markedly reduced in cells showing the transformed phenotype. The accumulation of newly synthesized core protein of syndecan-1 was suppressed in these cells, whereas mRNA levels remained unchanged. This novel finding indicates that syndecan-1 expression is translationally suppressed in the Ha-ras-transformed epithelial cells. Hence, syndecan-1 loss during epithelial transformation could take place without altering syndecan gene transcription and, on the other hand, could be one of the critical events involved in malignant transformation.
Kirjavainen
J
J
Department of Medical Biochemistry, University of Turku, Finland.
Leppä
S
S
Hynes
N E
NE
Jalkanen
M
M
D000818:Animals; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D004847:Epithelial Cells; D005455:Fluorescent Antibody Technique; D011905:Genes, ras; D008321:Mammary Glands, Animal / Q000166:cytology / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000096:biosynthesis* / Q000235:genetics; D051379:Mice; D010641:Phenotype; D017354:Point Mutation; D014176:Protein Biosynthesis; D011509:Proteoglycans / Q000096:biosynthesis* / Q000235:genetics; D053668:Syndecan-1; D053667:Syndecans
D008562:Membrane Glycoproteins; D011509:Proteoglycans; C508242:Sdc1 protein, mouse; D053668:Syndecan-1; D053667:Syndecans