Hepsin promotes breast tumor growth signaling via the TGFb-EGFR axis

Hepsin, a type II transmembrane serine protease, is commonly overexpressed in prostate and breast cancer. The hepsin protein is stabilized by the Ras-MAPK pathway, and downstream, this protease regulates the degradation of extracellular matrix components and activates growth factor pathways, such as hepatocyte growth factor and transforming growth factor beta (TGFß) pathway. However, how exactly active hepsin promotes cell proliferation machinery to sustain tumor growth is not fully understood. Here, we show that genetic deletion of Hpn in a WAP-Myc model of aggressive MYC-driven breast cancer inhibits tumor growth in the primary syngrafted sites and the growth of disseminated tumors in the lungs. The suppression of tumor growth upon loss of hepsin was accompanied by downregulation of TGFß and EGFR signaling together with a reduction in EGFR protein levels. We further demonstrate in 3D cultures of patient-derived breast cancer explants that neutralizing antibodies and small-molecule inhibitors of hepsin can be used to mitigate the hepsin-induced TGFß signaling and reduce EGFR protein levels.The study demonstrates a role for hepsin as a regulator of cell proliferation and tumor growth through TGFß and EGFR pathways, warranting consideration of hepsin as a potential indirect upstream target for therapeutic inhibition of TGFß and EGFR pathways in cancer. Overall design: 3' RNA-Seq (Drop-seq-like)