Project description: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 (TGFβ) 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 TGFβ 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 TGFβ signaling and reduce EGFR protein levels.The study demonstrates a role for hepsin as a regulator of cell proliferation and tumor growth through TGFβ and EGFR pathways, warranting consideration of hepsin as a potential indirect upstream target for therapeutic inhibition of TGFβ and EGFR pathways in cancer.
Project description:Epidermal growth factor receptor (EGFR) signaling is constitutively activated in majority of GBM and is associated with a worse prognosis. Here we show that EGFR is responsible for overexpression of the m6A "reader" YTHDF2 in GBM through the EGFR/Src/ERK signaling pathway. YTHDF2 overexpression clinically correlates with poor glioma patient prognosis. EGFR signaling stabilizes YTHDF2 protein through phosphorylation of YTHDF2 serine 39 and threonine 381 by ERK1/2. YTHDF2 is required for GBM cell proliferation, invasion and tumorigenesis. YTHDF2 facilitates m6A-dependent mRNA decay of LXRA and HIVEP2, both are genes impacting glioma patient survival. YTHDF2 promotes tumorigenesis of GBM cells largely through downregulation of LXRA and HIVEP2. Further, YTHDF2 inhibits LXRA-dependent cholesterol homeostasis in GBM cells. Together, our findings extend the landscape of EGFR downstream circuit, uncover novel function for YTHDF2 in GBM tumorigenesis, and highlight an essential role of RNA m6A methylation in cholesterol homeostasis.
Project description:Epidermal growth factor receptor (EGFR) signaling is constitutively activated in majority of GBM and is associated with a worse prognosis. Here we show that EGFR is responsible for overexpression of the m6A "reader" YTHDF2 in GBM through the EGFR/Src/ERK signaling pathway. YTHDF2 overexpression clinically correlates with poor glioma patient prognosis. EGFR signaling stabilizes YTHDF2 protein through phosphorylation of YTHDF2 serine 39 and threonine 381 by ERK1/2. YTHDF2 is required for GBM cell proliferation, invasion and tumorigenesis. YTHDF2 facilitates m6A-dependent mRNA decay of LXRA and HIVEP2, both are genes impacting glioma patient survival. YTHDF2 promotes tumorigenesis of GBM cells largely through downregulation of LXRA and HIVEP2. Further, YTHDF2 inhibits LXRA-dependent cholesterol homeostasis in GBM cells. Together, our findings extend the landscape of EGFR downstream circuit, uncover novel function for YTHDF2 in GBM tumorigenesis, and highlight an essential role of RNA m6A methylation in cholesterol homeostasis.