The SCN9A channel and plasma membrane depolarization promote cellular senescence through Rb pathway

Oncogenic signals can induce premature senescence (OIS) in normal human cells causing a proliferation arrest and the elimination of these defective cells by immune cells. In order to identify new regulators of OIS, we performed a loss-of-function genetic screen and identified that the loss of SCN9A sodium channel allowed cells to escape from OIS. Here we studied the transcriptome profiles of an OIS model based on human mammary epithelial cells stably expressing hTert to be immortalized and MEK:ER, a 4-hydroxytamoxifen (4-OHT) inducible oncogene MEK:ER (HEC-TM cells), to induce the oncogenic signal. We used an shRNA in order to knockdown SCN9A expression during OIS, and KCL treatment to study the impact of membrane depolarization on senescence induction. We showed that SCN9A and plama membrane depolarization mediated the repression of mitotic genes through a calcium/Rb/E2F pathway to promote senescence. Taken together, our work delineates a new pathway, which involves the NFkB transcription factor, SCN9A expression, plasma membrane depolarization. For each condition three independent biological replicates were analysed. Untreated HEC-TM cells condition have been used as control and the data have been normalized on this control.