Increased expression of sialic acid in cervical biopsies with squamous intraepithelial lesions

Abstract

Background: Altered sialylation has been observed during oncogenic transformation. Sialylated oligosaccharides of glycoproteins and glycolipids have been implicated in tumor progression and metastases. In the cervical cancer high levels of sialic acid have been reported in the patients serum, and an increased of total sialic acid concentration has been reported for the cervical neoplasia and cervical cancer. This study investigates the changes in expression and distribution of α2,3-linked sialic acid and α2,6- linked sialic acid in low and high squamous intraepithelial lesions and in normal tissue.

Methods: Lectin histochemistry was used to examine the expression and distribution of sialic acid in different grades of cervical neoplasia. We applied Maackia amurensis lectin, which interacts with α2,3-linked sialic acid and Sambucus nigra lectin specific for α2,6-linked sialic acid.

Results: The histochemical analysis showed that α2,3-linked sialic acid and α2,6- linked sialic acid increased in intensity and distribution in concordance with the grade of squamous intraepithelial lesion (SIL). These results are in concordance with a previous study that reports increased RNAm levels of three sialyltransferases.

Conclusions: These results show that the change in sialylation occurs before cancer development and may play an important role in cellular transformation. These findings provide the basis for more detailed studies of the possible role of cell surface glycoconjugates bearing sialic acid in the cellular cervix transformation.

Figure 1

α2,3 Sialic acid expression in cervical samples with normal (A), LSIL (B) and HSIL (C) diagnosis. Sialic acid in α2,3 linkage was recognized with biotinylated MAA lectin. Amplification 100×.

Figure 2

α2,6 Sialic acid expression in cervical samples with normal (A), LSIL (B) and HSIL (C) diagnosis. Sialic acid in α2,6 linkage was recognized with biotinylated SNA lectin. Amplification 100×.