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Interaction of gangliosides with the methyltransferase‐I of microsomes from normal and neoplastic human mammary gland
Author(s) -
Losa Gabriele A.,
Graber Riccardo,
Chigorno Vanna,
Sonnino Sandro
Publication year - 1992
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.2910520512
Subject(s) - microsome , phosphatidylethanolamine , phospholipid , phosphatidylcholine , methyltransferase , mammary gland , biochemistry , ganglioside , biology , enzyme , endocrinology , sphingomyelin , medicine , chemistry , membrane , cancer , methylation , breast cancer , gene
The activity of the phospholipid methyltransferase‐1, which catalyzes the rapid transmethylation of phosphatidylethanolamine to phosphatidylcholine, was found to be about 6‐fold enhanced in microsomal membranes of breast cancer with respect to the level found in normal human mammary gland. Exogenous gangliosides GM1 and GM2 added to neoplastic breast microsomes induced progressive inhibition of the methyltransferase activity. In contrast, in microsomal membranes of non‐neoplastic breast tissue treated with these gangliosides, the methyltransferase activity was markedly increased. The addition of cholesterol to these microsomes led to complete inhibition of the GM1 ‐stimulated enzyme activity. The methyltransferase activity was not affected by GM3 alone in either type of tissue. Experiments carried out on non‐neoplastic microsomes revealed that the phospholipid methyltransferase‐1 was affected by that portion of gangliosides which remained stable associated to microsomal membranes. © 1992 Wiley‐Liss, Inc.