Design, synthesis and biological evaluation of novel small molecules inhibitors of c-Src, Hck and TAK1 Protein Kinases for treatment of cancer disease

The interest in protein kinase had been improved in recent years since the entry into the market of the first protein Kinase inhibitor. In this thesis have been designed, and synthesized new small molecules able to inhibit separately three different kinases, c-Src, Hck and TAK1, widely implicated in cancer disease. Protein kinases catalyse the transfer of phosphate groups from nucleoside triphosphates, usually adenosine triphosphate (ATP), to specific serine, threonine, or tyrosine residues in substrate proteins as a way of regulating their activities1,2. Deregulation of their activities can lead to severe diseases such as cancer3, which makes them desirable targets for drug design and therapeutic intervention4. In this context, Pyrazolo[3,4-d]Pyrimidines represent a promising class of compounds capable of inhibiting the first oncogenic tyrosine kinase discovered: c-Src. This class of compounds showed good inhibition properties toward c-Src in a cell-free assay, as well as antiproliferative activity toward different cell lines, blocking c-Src phosphorylation, and inducing apoptosis5,6 due to its isosterism with adenine scaffold of ATP, the natural phosphorylating agent that bind PTKs. In the first part of this thesis, had been designed a rational study to improve binding affinity to c-Src, without forget the importance of ADME properties, one of the most reason for drug discovery failure. Starting from X-ray crystal structure7 and Monte Carlo/Free Energy Perturbation on our hit compound, it was possible to design and synthesize compound 13e, characterized by a significant improvement of inhibitory activity against c-Src (IC50 7nM). Furthermore, new aminothiazole and aryl-amido derivatives were designed and synthesized, showing an interesting inhibitory profile too. A similar study had been applied to Hematopoietic Cell Kinase, suggesting the synthesis of new small molecule inhibitors. Instead, for the development of TAK1 inhibitors was applied a different strategy; an irreversible inhibition study was designed, leading to synthesize molecules able to form covalent bond with Cys174 of that kinase. Once identified the hit compound, different electrophiles had been inserted in order to trap cysteine of interest.