## 4 Discussion  
Breast cancer is a heterogeneous disease consisting of different subtypes with varying prognosis [34]. Breast cancer treatment resistance is common and increases mortality [35].Tumour cells produce increased levels of SA [7]. It has been reported that overexpression of SA in metastatic cancer controls the tumour cell growth and differentiation by interfering with neural cell adhesion molecule signalling \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Mean Volume [um\({}^{3}\)]** & \(p\) **value** & **Mean Area [um\({}^{2}\)]** & \(p\) **Value** & **Mean Thickness** [um] & \(p\) **Value** \\ \hline MCF-7 Control & 2600 (\(\pm\)15) & **0.027** & 685 (\(\pm\)15) & 0.306 & 3.8 (\(\pm\)18) & **0.024** \\ \hline MCF-7 SA-MIPs & 3190 (\(\pm\)11) & 628 (\(\pm\)8) & 628 (\(\pm\)8) & 4.8 (\(\pm\)10) & & 4.8 (\(\pm\)10) \\ \hline MDAMB231 Control & 2825 (\(\pm\)4) & **0.005** & 574 (\(\pm\)21) & 0.247 & 5.1 (\(\pm\)46) & 0.797 \\ \hline MDAMB231 SA-MIPs & 3471 (\(\pm\)15) & 666 (\(\pm\)11) & & 5.0 (\(\pm\)14) & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Morphology parameters detected with DHC for MCF-7 cells and MDAMB231 cells after 72 h of SA-MIPs treatment. The results represent mean value of five positions in the wells for each condition. Statistical significance was determined with \(p\) values \(\leq\) 0.05. Figure 4: Cell viability assay with MCF-7 cells and MDAMB231 cells treated with 0.04 mg/mL of SA-MIPs or left as a control for three time points, 24, 48 and 72 h. The absorbance was measured at 490 nm. The results represent the mean value of five replicate wells for each condition and repeated at least twice with similar results. Statistical significance was determined with \(p\) values \(\leq\) 0.05 \({}^{\star}\), \(\leq\)0.01 \({}^{\star\star}\), \(\leq\)0.001 \({}^{\star\star}\). at cell-cell contacts [36]. The MCF-7 cell line expresses high SA levels, mainly with \(\alpha\)-2,3 linkage, and was detected to a higher extent with SA-MIPs and MALI using flow cytometry, while MDAMB231 expresses high SA (\(\alpha\)-2,3) levels as detected with MALI and SNA. In this study, we investigated the cell motility using DHC for the two breast cancer cell lines MCF-7 and MDAMB231. Here, we show that MDAMB231 cells have higher motility compared to MCF-7 cells. These observations are in agreement with the existing evidence that show that MDAMB231 cells are more motile and invasive than the MCF-7 cells, which are generally less invasive and have poor migration capabilities [37]. The MCF-7 cell line represents a non-motile epithelial cell line with the ability to retain the ideal features of the mammary epithelium with low-risk of metastasis [37; 38]. The MDAMB231 cell line is a highly motile, aggressive, invasive and poorly differentiated triple-negative breast cancer cell line. The MDAMB231 cell line mediates proteolytic degradation in the extracellular matrix and contributes to invasiveness and metastasis formation by varying morphological characteristics [39; 40]. The two cell lines showed different morphologies and different motility patterns. The cell volume significantly increased after SA-MIPs treatment for both cell lines, suggesting ingestion or binding of SA-MIPs. These results agree well with a recent study in which we showed that the increase in cell size of macrophages was a response to SA-MIPs treatment [41]. [PERSON] et al. have shown that the very thin outer part of the cells are not detected by DH microscopy, and therefore the cell volume measurements can be misleading [42]. The outer parts of the cells used in the present study can be detected using the HoloMonitor as the cells are thicker and do not spread as much as the cells used by [PERSON] et al. The findings of this study showed that SA-MIPs affected the cell viability of the cell lines at different stages during the experiment. Here, a decrease in cell viability for the MCF-7 cell line treated with SA-MIPs after 24 h, 48 h and 72 h, correlated inversely with increased cell motility.