Cell and nuclear size are associated with chromosomal instability and tumorigenicity in cancer cells that undergo whole genome doubling

Whole genome doubling (WGD) is a frequent event in cancer evolution associated with chromosomal instability, metastasis, and poor prognosis. While the genomic consequences of WGD are well documented, the effects of non-genetic alterations that accompany WGD, such as changes to cell and nuclear size, on tetraploid (4N) cancer cell physiology are less understood. Here, we show that cell and nuclear volume do not always scale with DNA content after WGD in cancer cells, resulting in 4N cells that differ in size. We find that small size is associated with enhanced cell fitness, mitotic fidelity, and tumorigenicity in 4N cancer cells and with poor patient survival in WGD-positive human cancers. Overall, these results suggest that cell and nuclear size contribute to the tumorigenic potential of 4N cancer cells and could be an important prognostic marker in human tumors that undergo WGD. Overall design: Single cell tetraploid clones that differ in cell and nuclear size, but not ploidy, were generated from near-diploid breast and colorectal cancer cell lines. Tetraploidy was induced in DLD1 by exposing cells to 1.5ug/mL dihydrocytochalasin for 20 hr. In HCT116 and CAL51, cytokinesis failure was induced by adding 75 µM blebbistatin to the culture medium for 20 hr. Drugs were washed out four times in media. The cells were allowed to recover for 48 hr before performing single cell cloning via limiting dilution in 96-well plates. Transcriptional profiling was performed on the small and large tetraploid clones to identify differences in gene expression.