PROGETTO AIRC IG.2019 ID 23341 PROF. DI CUNTO 4° ANNUALITA' TITOLO PROGETTO" DEVELOPMENT OF CITRON KINASE ES A THERAPEUTIC TARGET FOR BRAIN TUMORS

Background High grade brain tumors (HGBT), in particular medulloblastoma (MB) and glioblastoma multiforme (GBM) are an important unmet medical challenge. MB is the most common pediatric HGBT, currently treated with surgery, irradiation and chemotherapy. Despite recent progress, MB is still associated to relatively high lethality and dramatic neurological and endocrine side effects. On the other hand, GBM represents 12-15% of all brain tumors and is one of the deadliest human cancers, with longest median survival of 14 months, despite maximal treatment. For these reasons, more effective and specific therapies for these tumors are urgently needed. Hypothesis A possible strategy to develop new anti-cancer therapies is to target molecules that, despite not being mutated, are required for tumor growth and progression. During the previous period of funding we have validated Citron kinase (CITK) as a promising target for MB therapy. CITK is not a cancer driver, but its deletion delays MB progression, by inducing DNA damage, cytokinesis failure, senescence and apoptosis. These effects depend on CITK catalytic activity. To move this new target forward in the drug discovery pipeline it will be essential to develop inhibitors of CITK activity, and test their efficacy and specificity. Moreover, it will be fundamental to address whether CITK inactivation/inhibition may increase the effectiveness of current therapies, especially radiotherapy. Aims 1) We plan to address in vivo the effectiveness of combining CITK inactivation with IR or/and chemotherapy in MB models. 2) We will explore whether CITK can be a promising target also for GBM treatment. 3) We will analyze the biological effects of kinase inhibitors known to bind CITK with reasonable affinity and to assess whether their effects depend on CITK. 4) We will conduct a collaborative effort aimed at identifying potent and specific CITK inhibitors. 5) We will study new CITK interactors and possible substrates to increase the mechanistic understanding of CITK functions. Experimental Design In vivo studies will be pursued using conditional CITK deletion models which we have previously developed, to conduct sophisticated analyses and treatments closely simulating the diagnostic and therapeutic path of patients, including MRI and high-energy tomotherapy. The screen for novel inhibitors will be conducted in collaboration with Experimental Therapeutic Program of IFOM and will be supported by the Structural Biology Unit of IEO and by the company AXXAM. In vitro studies will be conducted on different MB and GBM models, including 3D cultures of tumor stem cells. Expected Results We expect that the results of our studies will provide clear indications about the suitability of CITK as a target for combined therapy in MB and GBM and will increase our understanding of CITK functions. Moreover, they should establish whether CITK inactivation is a component of the activity of some approved anti-tumor drugs. Finally, we should be able to provide lead CITK inhibitors for pharmacological development. Impact On Cancer Since CITK is a neglected 'druggable' molecule, the main impact of our studies in pre-clinical models would be to make an even stronger case for pursuing development of CITK-directed drugs and provide a solid basis for their development.