Susann M. Brady-Kalnay, PhD
Professor, Molecular Biology and Microbiologysmb4@case.edu 216.368.0330 (o) 216.368.3055 (f)
Member, Cancer Imaging Program
Receptor Protein Tyrosine Phosphatases, cell-cell adhesion and signal transduction: We are studying the role of receptor protein tyrosine phosphatases (RPTPs) in signals transduced upon cell-cell contact. Some RPTPs such as PTPµ have cell adhesion molecule-like extracellular segments and are involved in adhesion-dependent signaling. PTPµ mediates adhesion by binding homophilically, i.e., PTPµ on the surface of one cell binds to PTPµ on an apposing cell. Interestingly, we found that PTPµ associates with another family of cell adhesion molecules called cadherins. Cadherins are adhesion molecules that play a role in cytoskeletal organization and cell junction formation. We are investigating the role of RPTPs and tyrosine phosphorylation in assembly and signal transduction at sites of cell-cell adhesion.
RPTPs and cancer: We are investigating the role of RPTPs in cell growth and malignancy in cancer. Protein tyrosine kinases can cause uncontrolled cell growth by disrupting the balance of cellular phosphotyrosine levels suggesting that PTPs may play an important role in negative growth regulation or could function as tumor suppressors. In this regard, we have recently found that certain cancer cells have lost PTPµ expression. Therefore, we are determining whether restoration of PTPµ expression in cancer cells results in changes in adhesion, growth, tumorigenicity or metastasis.