RNA-Seq analysis of 4N and 2N RPE1 cells following polyploid induction via cytokinesis failure by siRNA knockdown of Anillin [tpo8]

Tetraploidization, or genome doubling, is a prominent event in tumorigenesis, primarily because cell division in polyploid cells is error-prone and produces aneuploid cells. This study investigates changes in gene expression evoked in acute and adapted tetraploid cells and their impact on cell-cycle progression. Acute polyploidy was generated by knockdown of essential regulator of cytokinesis Anillin, which resulted in cytokinesis failure and formation of binucleate cells, or by chemical inhibition of Aurora kinases, causing abnormal mitotic exit with formation of single cells with aberrant nuclear morphology. Transcriptome analysis of these acute tetraploid cells revealed common signatures of activation of the tumor-suppressor protein p53. Suppression of proliferation in these cells was dependent on p53 and its transcriptional target - Cdk inhibitor p21. Rare proliferating tetraploid cells can emerge from acute polyploid populations. Gene expression analysis of single-cell derived, adapted tetraploid clones showed upregulation of several p53 target genes and cyclin D2, the activator of Cdk4/6/2. Overexpression of cyclin D2 in diploid cells strongly potentiated the ability to proliferate with increased DNA content despite the presence of functional p53. These results point out that p53-mediated suppression of proliferation of polyploid cells can be averted by increased levels of oncogenes such as Cyclin D2, elucidating a possible route for tetraploidy-mediated genomic instability in carcinogenesis. Overall design: Three biological replicates of cells treated with siRNA against Anillin or a non-targeting control are FACS sorted into 2N or 4N populations and assessed for gene expression differences via RNA Seq for a total of 12 samples.

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Potapova TA, Seidel CW, Box AC, Rancati G, Li R