Branched Peptides for Therapy

Heparan sulfate proteoglycans (HSPGs) are key regulators of multiple cellular processes and are increasingly recognized for their role in cancer development and progression, due to their ability to control a plethora of different functions, such as organization of the ECM, cell migration and proliferation. In this thesis, we first exploited our anti-heparan sulfate branched peptide NT4 to target HSPGs and interfere with their functions, instead of using heparin as a soluble competitor in human cancer cells. We found that NT4 is more effective than heparin for inhibiting cancer cell adhesion, directional migration, colony formation and even cell growth, suggesting that targeting membrane-associated HSPGs may represent a more effective anti-metastatic strategy than the use of soluble heparin. In parallel, we investigated expression and functional relevance of HSPGs in various models of epithelial to mesenchymal transition (EMT), a well-known process whereby tumor cells become more aggressive and motile, acquiring a mesenchymal phenotype able to disseminate and metastasize. This study revealed a significant HSPGs reprogramming associated with EMT, characterized by their overexpression across mesenchymal models, with a signature shared across species and experimental systems. Furthemore, we demonstrated that NT4 inhibits the migration of MMTV-PyMT mouse organoids. Overall, these findings suggest a strong HSPGs contribution to pro-migratory and invasive signalling in tumoral context, and support their potential as targets for limiting tumor progression. In the final part of the thesis, we employed a phage display strategy to identify novel peptides capable of interfering with sclerostin, with the ultimate goal of developing therapeutic candidates for osteoporosis. Although no peptide with specific binding activity was found, the setup of methodological approaches could be exploited for future studies.