MG132 Proteasome Yet, in colon cells are in a specialized 3D tissue with cell/cell contacts which strongly influence cell behaviour. Such an effect is not reproduced in our 2D in vitro experiments. Nevertheless, our in vitro model is more appropriate for single tumour cells or small groups of cells that escape the tumour mass to invade the stroma and engage in the process leading to metastasis formation after a long journey through tissues of very different Young moduli. Altogether, our results show that the decrease of the stiffness correlates with an increase in cell lethality in vitro for healthy as well as cancerous cells. Nonetheless, very importantly, we observed that some cancer cells can escape from very soft substrates and can achieve mitosis.

These findings are highly relevant for both normal homeostasis of solid tissues and for pathological settings. Table 1 Apparent elastic modulus of (PLL/HA)24-(PSS/PAH)n with n = 1 and 2. Figure 2 PEM characterization. Figure 3 SW480 cells progression through mitosis with respect to elastic moduli of the substrate. Figure 4 Behavior of asynchronous HCoEpiC cells on E50. 2. Behavior of tumor cells bearing chromosome segregation abnormalities Time-lapse monitoring chromosome segregation showed that SW480 cells seeded on E50 and on E20 displayed lagging chromosomes (Figure 3B, arrows) indicating defects in chromosomal segregation mechanisms. In late telophase, the nuclei reformed and cytokinesis completed (Figure 3B, 3D and Movie S5 and S6). Among the SW480 cells progressing through mitosis 4.

8%, 11% and 13% showed chromosome segregation abnormalities on glass, E50 and E20, respectively. These results showed that despite increasing frequency of abnormalities induced by soft substrates, some SW480 cancer cells are able to progress through mitosis. Which is consistent Brefeldin_A with observation made on rigid substrates that cells having deficient spindle checkpoint mechanisms may proceed through mitosis even in the presence of chromosomes misconnected to the spindle [22]. 3. The ��1-integrin engagement by mitotic tumor cells in response to soft substrates Interactions with the extracellular matrix through integrins have been shown to influence different aspects of mitotic spindle organization [23,24]. In particular, it is well known that mitotic cells become rounded in preparation for cytokinesis and remain attached to the substrate through retraction fibres via integrin engagement [25]. The retraction fibres provide resistive force that propagates within microtubules to orient the mitotic spindle [23-26]. We thus investigated the effects the different substrate stiffness on ��1-integrin in SW480 cells.