Modulation of the aspartic acid scaffold to identify a new septin-4 covalent binder with anti-metastatic activity in a mouse model of melanoma

Tumour metastases are still the leading cause of cancer-related death, being often responsible for the failure of current therapies.[1] In our previous work, we have developed a compound, AA6, that proved able to counteract the metastatic spread in a mouse model of breast cancer.[2] To identify the essential structural elements and the cellular target involved in the activity of our lead compound, a new series of AA6-derivatives was designed and synthesised. New compounds were tested for the inhibitory activity on tumour cell invasion, migration and adhesion in B16-F10 melanoma cells. From the in vitro results, compound CM365 was selected as the most promising derivative, showing good efficacy and most likely able to interact with the target through covalent binding. To pinpoint the cellular target, a proteomic analysis was carried out and this allowed to select septin-4 as the most likely protein involved. Septins are GTP-binding proteins, able to assemble into large filaments on the plasma membrane, modifying its rigidity in migrating cells and promoting tumour metastasis.[3] To study and compare the binding modes of the two derivatives, AA6 and CM365, with the molecular target, computational analyses were performed. Finally, the anti-metastatic properties of CM365 were evaluated in vivo in a murine model of metastatic melanoma. This compound proved capable of reducing metastases dissemination at different times of administration and of enhancing the antitumour effect of a known anticancer drug, paclitaxel, when administered in combination. The discovery of septin-4 as a new molecular target for the prevention of metastatic spread may encourage the future development of more specific inhibitors. References: [1] A. Chatterjee, E. J. Roger et all, Semin. Cancer Biol., 2018, 51, 149–159. [2] S. Atlante, A. Visentin, Cell Death Dis., 2018, 9, 756 [3] C. Poüs, L. Klipfel, Front. Cell Dev. Biol., 2016, 4, 126.