Inhibition of Glycosidases in Breast Cancer Cell Lines: Observations from 2D and 3D Cell Culture Systems

Breast cancer presents a significant challenge in oncology due to its diverse nature and varying treatment responses among subtypes, particularly in triple-negative breast cancer (TNBC). A growing body of research highlights the role of glycosidases in the aberrant glycosylation associated with breast cancer progression.

This study assessed iminosugar glycosidase inhibitors for their effect on breast cancer behaviour in vitro. TNBC cells (MDA-MB-231 and BT-549), oestrogen receptor-positive (MCF7) and HER2-positive cells (SKBR3) were assessed both in 2D and in 3D cell cultures.

As expected, alterations in glycosylation were observed using lectin fluorescence microscopy following treatment of the cancer cells with the inhibitor compounds 1-Deoxynojirimycin (DNJ), 255, 42, and 44, iminosugars provided in collaboration with the Phytoquest company. After glycosidase inhibitor treatment, a significant decrease in the cancer cell metabolic activity was assessed by Alamar Blue Assay. This was accompanied by a reduction in the cell count and reduced cell migration across both 2D and 3D cell culture. An additive effect was observed when doxorubicin was combined with the inhibitors in 2D. Additionally, this study assessed CIN in BC in vitro models using the CBMN assay. Higher rates of CIN were observed in 2D cultures compared to 3D. Given the known impact of glycosidase inhibition on oxidative stress and DNA damage, and on glycoproteins involved in cell cycle regulation, an effect of glycosidase inhibition on genomic instability could be expected. However, in this study, while treatment of the cells with glycosidase inhibitors was shown to influence cell viability and apoptosis, the effect on CIN was not statistically significant, warranting further investigation into the relationship between cytotoxicity and genomic stability. The observed differences between 2D and 3D cultures highlight the importance of incorporating extracellular matrix and biophysical cues when studying breast cancer behaviour. The observed additive effects of glycosidase inhibition alongside doxorubicin suggest this approach may enhance breast cancer responsiveness to chemotherapeutic drugs. This thesis contributes to understanding the potential role of glycosidase inhibitor compounds in modulating breast cancer behaviour. It sets the stage for future research concerned with improving breast cancer outcomes.