Molecular nature and possible presence of a membranous glycan-phosphatidylinositol anchor of CA125 antigen.
The molecular nature and possible presence of a glycan-phosphatidylinositol anchor (GPI-anchor) in CA125 molecules was investigated. Serial lectin affinity chromatography and N- or O-glycanase treatment to reduce antigenicity showed that CA125 contained certain N- and O-glycosylated sugar chains in the molecule, like a glycoprotein. CA125 released from ovarian cancer tissues increased time-dependently following phosphatidylinositol-specific phospholipase C (PI-PLC) treatment, concomitant with the release of tissue-unspecific alkaline phosphatase. Western blotting of CA125 treated by PI-PLC showed a single band of 90 kD instead of the 162- and 76-kD bands of the native antigen. Further, ovarian cancer tissues subjected to PI-PLC treatment lost the immunohistochemical localization of CA125 with OC125 antibody. Consequently, it is strongly suggested that CA125 is a glycoprotein that has both N- and O-linked sugar chains and a membranous GPI-anchoring moiety, and further, that its 90-kD form is the antigen without the GPI-anchor.
Nagata
A
A
Immunology Laboratory, Yamasa Shoyu Co., Ltd., Chiba, Japan.
Hirota
N
N
Sakai
T
T
Fujimoto
M
M
Komoda
T
T
D000230:Adenocarcinoma / Q000276:immunology*; D000469:Alkaline Phosphatase / Q000378:metabolism; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000737:chemistry / Q000378:metabolism*; D015153:Blotting, Western; D002846:Chromatography, Affinity; D005260:Female; D006026:Glycoside Hydrolases; D017261:Glycosylphosphatidylinositols; D006801:Humans; D007150:Immunohistochemistry; D015592:Immunoradiometric Assay; D015394:Molecular Structure; D010051:Ovarian Neoplasms / Q000276:immunology*; D010716:Phosphatidylinositols / Q000737:chemistry / Q000378:metabolism*; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism*; D010738:Type C Phospholipases / Q000378:metabolism
D015295:Antigens, Tumor-Associated, Carbohydrate; D017261:Glycosylphosphatidylinositols; D010716:Phosphatidylinositols; D011134:Polysaccharides; D000469:Alkaline Phosphatase; D010738:Type C Phospholipases; D006026:Glycoside Hydrolases