Reduced contact-inhibition and substratum adhesion in epithelial cells expressing GlcNAc-transferase V.
Malignant transformation of fibroblast and epithelial cells is accompanied by increased beta 1-6 N-acetylglucosaminyltransferase V (GlcNAc-TV) activity, a Golgi N-linked oligosaccharide processing enzyme. Herein, we report that expression of GlcNAc-TV in Mv1Lu cells, an immortalized lung epithelial cell line results in loss of contact-inhibition of cell growth, an effect that was blocked by swainsonine, an inhibitor of Golgi processing enzyme alpha-mannosidase II. In serum-deprived and high density monolayer cultures, the GlcNAc-TV transfectants formed foci, maintained microfilaments characteristic of proliferating cells, and also experienced accelerated cell death by apoptosis. Injection of the GlcNAc-TV transfectants into nude mice produced a 50% incidence of benign tumors, and progressively growing tumors in 2:12 mice with a latency of 6 mo, while no growth was observed in mice injected with control cells. In short term adhesion assays, the GlcNAc-TV expressing cells were less adhesive on surfaces coated with fibronectin and collagen type IV, but no changes were observed in levels of cell surface alpha 5 beta 1 or alpha v beta 3 integrins. The larger apparent molecular weights of the LAMP-2 glycoprotein and integrin glycoproteins alpha 5, alpha v and beta 1 in the transfected cells indicates that their oligosaccharide chains are substrates for GlcNAc-TV. The results suggest that beta 1-6GlcNAc branching of N-linked oligosaccharides contributes directly to relaxed growth controls and reduce substratum adhesion in premalignant epithelial cells.
Demetriou
M
M
Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario.
Nabi
I R
IR
Coppolino
M
M
Dedhar
S
S
Dennis
J W
JW
D008841:Actin Cytoskeleton / Q000648:ultrastructure; D000818:Animals; D015703:Antigens, CD; D017209:Apoptosis; D002448:Cell Adhesion; D002460:Cell Line; D002465:Cell Movement; D002470:Cell Survival; D003260:Contact Inhibition; D004847:Epithelial Cells; D051907:Lysosomal Membrane Proteins; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D008907:Mink; D017351:N-Acetylglucosaminyltransferases / Q000378:metabolism*; D009374:Neoplasms, Experimental / Q000209:etiology; D009844:Oligosaccharides / Q000378:metabolism; D017026:Swainsonine / Q000494:pharmacology; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000494:pharmacology
D015703:Antigens, CD; D051907:Lysosomal Membrane Proteins; D008562:Membrane Glycoproteins; D009844:Oligosaccharides; D016212:Transforming Growth Factor beta; D017351:N-Acetylglucosaminyltransferases; C052254:alpha-1,6-mannosylglycoprotein beta 1,6-N-acetylglucosaminyltransferase; D017026:Swainsonine