Biological Implications of Surface Immunoglobulins Expressed by Cancer Cells

RP215 was one of monoclonal antibodies generated against the extract of OC-3VGH ovarian cancer cells. It was shown to react with a carbohydrate-associated cancer antigen designated as CA215, consisting mainly of immunoglobulin (Ig) heavy chains (expressed by cancer cells) as well as several other immunoglobulins superfamily proteins (IgSF). RP-215-specific epitope in CA215 was elucidated by comprehensive glycoanalysis and was shown to be associated with O-linked Sialyl-T glycans located in the variable regions of heavy chain immunoglobulins. RP215 and its humanized forms were shown to induce apoptosis upon incubation with culturing cancer cells of many tissue origins. Relevant functional roles of CA215 were evaluated through the use of affinity-purified CA215 and cancerous Ig’s to capture those specific interacting human serum proteins in circulation. Through analysis by LC-MS/MS methods, greater than 80% of the identified serum proteins were commonly recognized by both CA215 or cancerous IgG as the capturing ligands.