title: Ionizing radiations increase the activity of the cell surface glycohydrolases and the plasma membrane ceramide content.
abstract: We detected significant levels of β-glucosidase, β-galactosidase, sialidase Neu3 and sphingomyelinase activities associated with the plasma membrane of fibroblasts from normal and Niemann-Pick subjects and of cells from breast, ovary, colon and neuroblastoma tumors in culture. All of the cells subjected to ionizing radiations showed an increase of the activity of plasma membrane β-glucosidase, β-galactosidase and sialidase Neu3, in addition of the well known increase of activity of plasma membrane sphingomyelinase, under similar conditions. Human breast cancer cell line T47D was studied in detail. In these cells the increase of activity of β-glucosidase and β-galactosidase was parallel to the increase of irradiation dose up to 60 Gy and continued with time, at least up to 72 h from irradiation. β-glucosidase increased up to 17 times and β-galactosidase up to 40 times with respect to control. Sialidase Neu3 and sphingomyelinase increased about 2 times at a dose of 20 Gy but no further significant differences were observed with increase of radiation dose and time. After irradiation, we observed a reduction of cell proliferation, an increase of apoptotic cell death and an increase of plasma membrane ceramide up to 3 times, with respect to control cells. Tritiated GM3 ganglioside has been administered to T47D cells under conditions that prevented the lysosomal catabolism. GM3 became component of the plasma membranes and was transformed into LacCer, GlcCer and ceramide. The quantity of ceramide produced in irradiated cells was about two times that of control cells.
authors.affiliation: Department of Medical Chemistry, Biochemistry and Biotechnology, University of Milan, Milan, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Aureli
authors.forename: Rosaria
authors.initials: R
authors.lastname: Bassi
authors.forename: Alessandro
authors.initials: A
authors.lastname: Prinetti
authors.forename: Elena
authors.initials: E
authors.lastname: Chiricozzi
authors.forename: Brigida
authors.initials: B
authors.lastname: Pappalardi
authors.forename: Vanna
authors.initials: V
authors.lastname: Chigorno
authors.forename: Nadia
authors.initials: N
authors.lastname: Di Muzio
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Loberto
authors.forename: Sandro
authors.initials: S
authors.lastname: Sonnino
mesh_terms: D017209:Apoptosis / Q000528:radiation effects; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000201:enzymology / Q000528:radiation effects*; D049109:Cell Proliferation / Q000528:radiation effects; D002518:Ceramides / Q000378:metabolism*; D005347:Fibroblasts / Q000201:enzymology / Q000378:metabolism / Q000528:radiation effects; D005732:Gangliosides / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000378:metabolism*; D006801:Humans; D011839:Radiation, Ionizing
chemical_list: D002518:Ceramides; D005732:Gangliosides; D006026:Glycoside Hydrolases