GalNAcα1‐3Gal, a new prognostic marker for cervical cancer

Abstract

Cancer cells undergo significant changes in carbohydrate expression, and these alterations can be useful as biomarkers and therapeutic targets. In this study, we investigated the expression of carbohydrate antigens containing a terminal GalNAca1-3Gal or GalNAca1-6Gal on human cervix and cervical carcinoma. Monoclonal antibodies to each of these carbohydrates were generated by immunizing rabbits with the corresponding antigen conjugated to KLH followed by hybridoma production. Antibodies were screened and evaluated using a combination of carbohydrate microarray profiling, ELISA, dot blot and immunohistochemical staining to verify specificity. Antibody 132-3 was found to selectively recognize GalNAca1-3Gal with little cross-reactivity to other structurally similar antigens such as GalNAca1-6Gal, blood group A, Forssman antigen and the Tn antigen on both solution assays and human tissue. Although GalNAca1-6Gal expression was not detected, GalNAca1-3Gal expression was found on 55% of squamous cell carcinomas. Expression in normal tissue was observed but was restricted to the suprabasal epithelial layer. Importantly, we found expression of the antigen on cervical cancer had a statistically significant correlation with the 5-year survival rate of the patients (48 vs. 85% for antigen negative vs. positive, p 5 0.017). Expression of GalNAca1-3Gal did not correlate with other clinical factors including tumor stage, size and lymph node metastasis, indicating the antigen is a new, independent biomarker for the prognosis of cervical cancer.

Recognition of the Thomsen-Friedenreich Pancarcinoma Carbohydrate Antigen by a Lamprey Variable Lymphocyte Receptor

“…These saccharides decorate mucin-type glycoproteins in ϳ90% of human cancers but are absent from nearly all normal tissues (1,2). A number of carbohydrate binding lectins and antibodies have been developed to detect expression of T-nouvelle antigen, TF␣, and other cancer-specific glycans for diagnostic and prognostic applications (2)(3)(4). However, most of these reagents display either broad specificity or low affinity for their target glycans and, therefore, have limited clinical utility (5,6).…”

“…These changes can affect interactions between tumor cell surface glycans and glycan binding receptors, which may determine the metastatic potential of the cancer cell. The best-studied tumor-associated carbohydrates are truncated glycans, such as T-nouvelle antigen (GalNAc␣) and ThomsenFriedenreich antigen (TF␣ 4 ; Gal␤1-3GalNAc␣), which are linked to serine or threonine as O-glycans (1). These saccharides decorate mucin-type glycoproteins in ϳ90% of human cancers but are absent from nearly all normal tissues (1,2).…”

Glycan Microarrays for Decoding the Glycome

“…To prevent these sorts of problems from stalling further carbohydrate-biomarker discovery, the same group has since developed exquisitely specific antibodies utilizing glycan array technology to rapidly screen hybridomas. One of these, an anti GalNAcαGal antibody, has since been used as a tool to predict the survival rate of cervical cancer patients (149). …”

Designing repeat proteins for biosensors and medical imaging

“…Detection of these events, such as phosphorylation and glycosylation, is thus biomedically important. Several carbohydrate-binding lectins and mammalian antibodies have been investigated for specific binding to glycosylated proteins; however, these binders generally suffer from low affinity and broad specificity, thus limiting their clinical utility [39][40][41][42]. Variable lymphocyte receptors (VLRs), which are LRRs involved in the adaptive immunity of jawless vertebrates, have been successfully engineered for recognition of several glycosylated proteins [12,43,44].…”