The research program deals with the synthesis, structural analysis, biological evaluation and a thorough investigation of the mechanism of action of novel compounds as potential antitumor agents able to inhibit STAT3 (Signal Trasducer and Activator of Transciption 3) and NF-kB (Nuclear Factor-KappaB), both factors being significantly involved in tumor progression and metastasis. STATs are a family of latent, cytoplasmic transcription factors that are activated in response to extracellular signals such as cytokines, growth factors and hormones. STATs directly transmit signals from plasma membrane to the nucleus and regulate cell growth and survival by modulating the expression of specific target genes. STAT3 was found to be constitutively activated by aberrant upstream tyrosine kinase activity in a broad spectrum of cancer cell lines and human tumors, and is considered a promising target for cancer therapy. In addition, several studies confirmed that STAT3 inhibitors have minimal effects on normal cells, thus providing the potential for selective tumor cell elimination. NF-kB signalling is essential for estrogen receptor-negative (ER-) breast cancer tumorigenesis, progression and metastasis. Furthermore, the role of NF-kB in expressing pro-inflammatory cytokines and enzymes contribute to the strong correlation between inflammation and breast cancer. The research project follows two complementary approaches: 1) Lead optimization 2) Synthesis of new derivatives 1) Recently we identified an oxadiazole derivative (MD77) as a potential lead, able to inhibit STAT3 in a dose dependent manner (Dual-luciferase assay in HCT-116 cells) and to bind STAT3 SH2 domain (AlphaScreen-based assay). The compound displayed a significant growth inhibitory activity on a panel of 58 human cellular lines derived from 9 different types of tumor cells. Aim of the project is to obtain SAR data to optimize the pharmacophore what would allow the synthesis of antitumor agents provided with high selectivity and low toxicity. In parallel, on the bases of the encouraging results displayed both in vitro and in vivo by platinum complexes as direct and selective STAT3 inhibitors, the introduction of a methylamino group at position 4 of MD77 will be considered in order to coordinate platinum. In addition, different heterocycles appropriately substituted will be considered as ligands for platinum complexes. The project will be developed in the following directions: a) iterative modifications of the lead according to the classical principles of bioisostery, vinilogy, homology, stereochemistry. Computational (modeling and docking) and X-ray studies. c) Studies on the drug-protein adduct. 2) The designed compounds will be catechine derivatives, dithiolthiones, and diallyltrisulfid, possibly bound to molecules acting on different targets, to have a multiple mechanism of action. Dithiolthiones both of natural (D3T) and synthetic (oltipraz, anetolotrithione) origin, organosulfur compounds extracted from garlic as well as many natural polyphenoles are provided with chemoprotective activity and could play an important role in the prevention and/or treatment of cancer. In particular, dithiolthiones are reported to inhibit NF-kB while diallyltrisulfid is active against STAT3. Indeed, some of the new dithiolethione derivatives (ACS2, ACS15), that we have recently synthesized, significantly inhibited in vitro and in vivo cell proliferation (NSCLC xenograft in nude mice), enhancing E-cadherin and the tumor suppressor PP2A and exhibited antiangiogenic properties. Moreover, these compounds inhibited the activity and expression of several carcinogen activating enzymes as well as induced the expression of several carcinogen detoxification enzymes of the glutathione cycle. The biological evaluation and the investigation of the mechanism of action of all the synthesized compounds will be performed together with other research groups.