Aberrant sialylation and fucosylation of intracellular proteins in cervical tissue are critical markers of cervical carcinogenesis

Numerous studies have suggested that increased sialylation and fucosylation levels are signs of cancer progression. The majority of studies have focused on cell surface and bloodstream glycosylation changes associated with cancer progression, while little attention has been paid to changes in the glycosylation of cytosolic proteins. We compared the mannosylation, sialylation and fucosylation levels of cytosolic proteins obtained from human cervical tissues without neoplastic lesions vs. with cancer, using lectin blot and enzyme-linked lectin assay (ELLA) systems. There were no quantitative differences in mannosylation levels between the cytosolic proteins of normal and cancer tissues. However, we found markedly reduced sialylation (P<0.001) and fucosylation (P<0.01) in the proteins of cancer tissues. The ELLA system for detecting sialylation had extremely high sensitivity (91-100%) and specificity (82-100%) in distinguishing normal and cancer tissues. Thus, the changes in the glycosylation of cytosolic proteins during carcinogenesis of the cervix are quite different from previous observations concerning glycoconjugates in the bloodstream or on the cell surface. We suggest that changes in the glycosylation of intracellular proteins may be useful markers of the development of cervical cancer.