Brain metastases (BM) in
non-small-cell lung cancer (NSCLC) patients present an increasing clinical challenge. Identifying
biomarkers which specifically identify patients at high risk of BM may improve their early diagnosis, which is crucial for surgical and radiotherapeutic treatment outcome. Alpha-2,6-sialyltransferase (α-2,6-ST) and the primary product of its activity, alpha-2,6-galactose-linked
sialic acids (α-2,6-GalSA) have been found responsible for the adhesion of
tumor cells to the brain vessels' endothelium and enabling their transmigration through the blood-brain barrier in brain metastatic
tumors. The aim of the study was to investigate by histochemical method the presence and possible role of α-2,6-GalSA in the formation of brain
metastasis in NSCLC. In the screening phase 76 metastatic
brain tumors were stained for α-2,6-GalSA and the second phase involved an identical staining of 20 primary
tumors of patients who had their primary
tumors treated with surgery or definite
radiochemotherapy yet who later developed BM. The results were compared to a control group of 22 patients treated with surgery for NSCLC and who survived 5 years without the recurrence of disease. Alpha-2,6-GalSA presence was found to be down-regulated in poorly differentiated
tumor types, whereas majority of differentiated
tumors overexpressed it. This was statistically significant for both BM and the primary
tumors. The expression of α-2,6-GalSA remained stable in primary and metastatic
tumor pairs, however, no statistically significant differences were observed between study and control groups. Within the study group, a higher α-2,6-GalSA expression was associated with better overall survival, but not all statistical models found this result significant. Further studies are recommended to validate these findings.