DYRK2 activates heat shock factor 1 promoting resistance to proteotoxic stress in triplenegative breast cancer

To survive aneuploidy-induced proteotoxic stress, cancer cells activate the proteotoxic-stress response pathway, which is controlled by heat shock factor 1 (HSF1). This pathway supports cancer initiation, cancer progression and chemoresistance and thus is an attractive target. As developing HSF1 inhibitors is challenging, the identification and targeting of upstream regulators of HSF1 presents a tractable alternative strategy. Here we demonstrate that in triple negative breast cancer (TNBC) cells, the dual-specificity tyrosine-regulated kinase 2 (DYRK2) phosphorylates HSF1, promoting its nuclear stability and transcriptional activity. Thus, DYRK2 depletion reduces HSF1 activity and sensitises TNBC cells to proteotoxic stress. Importantly, in tumours from TNBC patients, DYRK2 levels positively correlate with active HSF1 and associates with poor prognosis, suggesting that DYRK2 could be promoting TNBC. In agreement with this, DYRK2 depletion reduces tumour growth in a TNBC xenograft model. These findings identify DYRK2 as both, a key modulator of the HSF1 transcriptional program, and a potential therapeutic target.