Figure 6

Polyploidy promotes primary tumor growth but opposes tumor recurrence. (A) Tumor volume curves for primary tumors (Her2 on; + dox) in mice injected with diploid or tetraploid tumor cells. (B) Mean growth rate of diploid and tetraploid primary tumor growth. Significance was determined using Welch’s t-test. (C) Minimum tumor volume following tumor regression in diploid and tetraploid tumors. The extent of tumor regression was calculated by dividing the minimum tumor volume following Her2 downregulation by the maximum tumor size. The dotted line represents 95% tumor regression. (D) The fraction of completely or incompletely regressing tumors in each cohort. Incomplete regression was defined as a minimum tumor volume > 5% of the tumor volume at de-induction. Differences in complete regression between cohorts as determined using Fisher’s exact test. Figure created using Adobe Illustrator (Illustrator CC 2021, version 25.0, https://www.adobe.com/products/illustrator.html). (E) Tumor volume curves for individual diploid and recurrent tumors. Mice were injected with cells between day − 150 and -100 and were removed from doxycycline to de-induce Her2 at Day 0. (F) Kaplan–Meier plot showing recurrence-free survival for diploid and tetraploid tumors following Her2 downregulation. Hazards Ratio (HR) and p value were determined using a log-rank test. (G) Median number of days to recurrence for diploid and tetraploid tumors. Significance was determined using Student’s t-test. *p < 0.05. (A–C and E–G) were generated using Graph Pad Prism 9 software (version 9.0.0 (86) for Mac, https://www.graphpad.com/scientific-software/prism/).