Binding of nuclear caveolin-1 to promoter elements of growth-associated genes in ovarian carcinoma cells.
Caveolin-1 (cav-1), a member of a protein family associated mainly with cell membrane microdomains in many cell types, acts as a tumor suppressor in ovarian carcinoma cells. Biochemical analyses demonstrated that cav-1 was also localized in the nuclei of ovarian carcinoma cells, endogenously (SKOV3) or ectopically (IGtC3) expressing cav-1. By confocal analyses, the same cell lines as well as IGROV1 and SKOV3 cells transiently transfected with green fluorescent protein-cav-1 fusion protein showed nuclear punctate speckled pattern. Subnuclear distribution analysis revealed cav-1 mainly associated with the nuclear matrix, but also slightly with chromatin. Cav-1 was found in nuclear high-molecular weight complexes and by confocal analysis was found to co-localized with the inner nuclear membrane protein emerin. Cyclin D1 and folate receptor promoters were modulated by cav-1 in SKOV3 cells as demonstrated by transient transfection with or silencing of cav-1. Chromatin immunoprecipitation and supershift assays indicated that nuclear cav-1 can bind in vitro and in vivo to promoter sequences of both cyclin D1 and folate receptor genes. These data suggest that in ovarian carcinoma cells cav-1, localized in transcriptionally inactive chromatin, exerts a functional activity mediated, at least in part, by directly binding to sequences of genes involved in proliferation.
Sanna
Elena
E
Unit of Molecular Therapies, Department of Experimental Oncology, Istituto Nazionale Tumori, 20133, Milan, Italy.
Miotti
Silvia
S
Mazzi
Mimma
M
De Santis
Giuseppina
G
Canevari
Silvana
S
Tomassetti
Antonella
A
D001483:Base Sequence; D002277:Carcinoma / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D051242:Caveolin 1 / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D049109:Cell Proliferation; D056741:Cyclin D; D016213:Cyclins / Q000235:genetics / Q000378:metabolism; D005260:Female; D058973:Folate Receptors, GPI-Anchored; D015972:Gene Expression Regulation, Neoplastic; D049452:Green Fluorescent Proteins / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D015530:Nuclear Matrix / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D002352:Carrier Proteins; D051242:Caveolin 1; D056741:Cyclin D; D016213:Cyclins; D058973:Folate Receptors, GPI-Anchored; D011956:Receptors, Cell Surface; D049452:Green Fluorescent Proteins