Figure 1

TWIST1 overexpression leads to cisplatin resistance and enhanced tumour cell engraftment.

(a) Western blotting demonstrates differential expression of TWIST1 between Ov8GFP stably transfected cell lines. Blots cropped for clarity; full blots are shown in Supplementary Fig. S5. (b) SRB assay demonstrates that TWIST1 expression leads to increased survival following exposure to cisplatin, particularly at lower doses (5, 10, and 20 μM, p < 0.0001; 40 μM, p = 0.0002). (c) Time lapse microscopy shows that across two logs of cisplatin doses, TWIST1 expression leads to faster growth of cells. TWIST1-expressing cells achieve greater confluence over time than TWIST1 knockdown cells at corresponding drug dose. Average slopes of the lines indicate a faster rate of growth for TWIST1 cells than sh492 cells until confluence is reached. Compare dark blue (slope = 1.15 over 48 hr) vs dark green (0.66 over 48 hr) and light blue (slope = 0.94 over 74 hours) vs light green (0.79 over 74 hr). (d) In vivo tumorigenesis assay shows that TWIST1-expressing cells give rise to widespread disseminated tumours, especially lining the wall of the peritoneal cavity. In contrast, sh492-expressing cells do not colonize the peritoneal wall. Arrows indicate carcinomatosis in mice engrafted with Ov8GFP-TWIST1 cells. All error bars represent standard error of the mean.