Molecular mechanisms of TGFbeta signaling

Our aim is to elucidate molecular mechanisms involved in TGFb signaling in breast cancer.

TGFb has both tumor suppressor (inhibits growth and induces apoptosis) and tumor promoting (stimulates invasiveness and metastasis) effects in cancer.

TGFb binds to type I and type II serine/threonine kinase receptors (TbRI and TbRII, respectively), and induces signaling via SMAD and non-SMAD pathways.We will determine the role of non-SMAD pathways, particularly activation of the tyrosine kinase SRC and cleavage of TbRI, liberating its intracellular domain (ICD), in pro-tumorigenic signaling of TGFb.In order to identify modulators of SMAD signaling, we have performed a whole genome CRISPR-Cas9 screen in the breast cancer cell line MDA-MB-231.

We have also performed a proteomic screen for binders of TbRI.

Based on the results of these screens, we will now investigate the effects of RHO/ROCK, integrin AV/B5, and CHD4 in TGFb signaling, using cell culture-based assays for TbRI, TbRII and SMAD activation, trafficking or stability.

In addition, the effects of their overexpression and knock-down on cell proliferation, survival, migration, invasion and epithelial-mesenchymal transition, will be determined.Identified pro-tumorigenic mechanisms will be further validated using mouse tumor models.Our goal is to make possible the development of clinically useful, selective TGFb antagonists, inhibiting only the pro-tumorigenic signaling pathways and not the tumor suppressive pathways of TGFb.