RNA Polymerase II subunits overexpressions induce genome instability and deregulate transcription

Independently of the pathways or circuits deregulated in cancer cells, these present altered transcription patterns, often also direct consequence of deregulation of transcription factors. In this sense, also the RNA Polymerase complexes responsible for transcription can be affected in cancers. We find that upregulations of RNA Polymerase II subunits, especially the largest ones, correlates with poor cancer patients outcome across a range of tumor types, presenting increased genome instability. Overexpressing the subunits RPB1, RPB3 and RPB4 in cells we find that these induce DNA damage. However, the mechanisms behind this increased genome instability are specific for each subunit, linked to the unique transcription alterations generated by the subunit overexpression. Importantly, we find significant overlap between the genes with more DNA damage in our cell line models and those more affected in cancers with subunit upregulation, indicating that upregulations could be responsible for some of the phenotypes present in these patients.