Expression of sulfatide and sulfated lactosylceramide among histological types of human ovarian carcinomas

Abstract

Among negatively charged lipids, sulfoglycolipids are known to be expressed by specific cell populations and to be involved in their functions, including in adhesion with functional proteins, modification of ion channels and induction of cellular differentiation. Accordingly, we determined their amounts in several histologically defined types of ovarian carcinoma tissues. Sulfoglycolipids were determined by TLC-immunostaining with monoclonal anti-sulfatide antibodies and the gene expression of their synthetic enzymes was by RT-PCR. All types of ovarian carcinomas were revealed to exhibit potential to synthesize sulfoglycolipids, either sulfatide (I(3)SO3-GalCer) or sulfated lactosylceramides (II(3)SO3-LacCer), which were expressed at the following frequencies, 6 out of 6 mucinous cystadenocarcinomas, 4 out of 7 serous cystadenocarcinomas, 2 out of 3 endometrioid carcinomas, and 2 out of 3 clear cell adenocarcinomas. All mucinous cystadenocarcinoma tissues preferentially contained sulfatide in amounts of 0.61-1.13 μg per mg dry weight, the molecular species being similar with those of GalCer. Whereas the other carcinomas contained either sulfatide or sulfated LacCer, the latter being detected in 4 out of 6 specimens with sulfoglycolipids. The expression of sulfatide and sulfated LacCer was found to be positively correlated with the amounts of GalCer and LacCer as substrates for sulfotransferase and expression of the genes for GalCer sulfotransferase and ceramide galactosyltransferase. Sulfoglycolipids in ovarian carcinoma tissues were revealed to be expressed in morphologically defined type-characteristic manners, in contrast to the ubiquitous distribution of GM3.