This study was aimed at obtaining insight into the diversity of
sialic acids in
cancer- and non-
cancer-related CA125
antigen, tumour marker of serous
ovarian cancer. Starting from available data suggesting the possible relevance of
sialic acids for discriminating CA125
antigens of different origin, we have employed a new experimental approach based on the use of human
sialic acid-binding Ig-like
lectins,
Siglecs, as tools for the investigation of sialylation.
Siglec-2, belonging to the group of evolutionarily conserved
Siglecs, and
Siglec-3, -6, -7, -9 and -10, which are CD33-like
Siglecs, were probed in solid-phase binding assays with
cancer-related CA125
antigens from pleural fluid of patients with ovarian
carcinoma (pfCA125), the OVCAR-3 ovarian
carcinoma cell line (clCA125) and a non-
cancer-related CA125
antigen, i.e. pregnancy-associated pCA125
antigen. All
Siglecs used showed detectable binding to pCA125
antigen.
Siglec-3, Siglec-7 and
Siglec-2 exhibited moderately stronger binding to pCA125
antigen than the others. In contrast to this,
Siglec-2 and
Siglec-3 preferentially recognized pfCA125 with greater total binding than for pCA125, whereas Siglec-9 and Siglec-10 were highly selective for clCA125.
Siglecs promise to be powerful tools for discriminating CA125 of different origin and could propagate further research on other molecular markers of biomedical and diagnostic importance.