CITK catalytic activity inhibition through Lestaurtinb leads to DNA damage, cytokinesis failure and cell death in brain tumors

Medulloblastoma (MB) and gliomas are the most frequent high-grade brain tumors (HGBT) in children and adulthood, respectively. The general treatment for these tumors consists in surgery, followed by radiotherapy and chemotherapy. Despite the improvement in patient survival, these therapies are only partially effective, and many patients still die, making these diseases an unmet medical challenge. Citron kinase (CITK), product of the primary microcephaly gene MCPH17, is required in neural progenitor cells for cytokinesis, mitotic spindle positioning and chromosomal stability. In vivo studies in xenograft models and in SHH MB arising in transgenic mice have shown that CITK deletion inhibits tumor progression. On this basis, we are working on the development of CITK inhibitors as a possible strategy for HGBT treatment. Stemming from published binding data between kinase inhibitors and the kinome, we discovered Lestaurtinib as CITK inhibitor. We therefore tested the biological effects of this inhibitor on different MB and GBM patient derived cell lines and in vivo injecting the drug in MBs arising in SmoA1 transgenic mice. In parallel, we developed a screening aimed at obtaining CITK specific inhibitors. Similar to CITK knockdown, treatment of MB cells with 100 nM Lestaurtinib reduces phospho-INCENP levels at the midbody and leads to cytokinesis failure. Moreover, Lestaurtinib impairs cell proliferation, leads to accumulation of DNA double strand breaks and cell death in MB and GBM cells. Finally Lestaurtinib treatment reduces tumor growth and increases mice survival. Moreover, our screening campaign produced several interesting hits that we are functionally validating. Our data indicate that Lestaurtinib produces in MB cells and in GBM cells phenotypes that recapitulate CITK knockdown effects. Reduced cell proliferation and increased mice survival indicate that Lestaurtinib and more specific CITK inhibitors are promising candidates for HGBT treatment, deserving deeper investigation.