SUMMARY
During this last decade the development of pro-senescence therapies has become an attractive strategy as cellular senescence acts as a barrier against tumour progression. In this context, CDK4/6 inhibitors induce senescence and have showed efficacy in reducing tumour growth in breast cancer patients. However, even though cancer cells are arrested after CDK4/6 inhibitor treatment, genes regulating senescence in this context are still unknown limiting their anti-tumour activity. Here, using a functional genome wide CRISPR/Cas9 genetic screen we found several genes that synergistically participate in the proliferation arrest induced by the CDK4/6 inhibitor, Palbociclib. We find that downregulation of the coagulation factor IX (F9) using sgRNA and shRNA prevents the cell cycle arrest and senescent-like phenotype induced in MCF7 breast tumour cells upon Palbociclib treatment. These results were confirmed using another breast cancer cell line and with an alternative CDK4/6 inhibitor, Abemaciclib, and further tested in a panel of 22 cancer cells. While F9 knockout reduces senescence, treatment with a recombinant F9 protein was sufficient to induce a cell cycle arrest and senescence-like state in MCF7 tumour cells. Besides, endogenous F9 is upregulated in different human primary cells cultures undergoing senescence. Importantly, bioinformatics analysis of cancer datasets suggest a role for F9 in human tumours. Altogether, these data collectively propose key genes involved in CDK4/6 inhibitors response that will be useful to design new therapeutic strategies in personalized medicine in order to increase their efficiency, stratify patients and avoid drug resistance.
Competing Interest Statement
The authors have declared no competing interest.