An in vivo active 1,2,5-oxadiazole Pt(II) complex: A promising anticancer agent endowed with STAT3 inhibitory properties.

New Pt(II) complexes (Pt-1-3) bearing 1,2,5-oxadiazole ligands (1-3) were synthesized, characterized and evaluated for their ability to disrupt STAT3 dimerization. Ligand 3·HCl showed cytotoxic effects on HCT-116 cells (IC50 = 95.2 µM) and a selective ability to interact with STAT3 (IC50 = 8.2 µM) versus STAT1 (IC50 > 30 µM). Its corresponding platinum complex Pt-3 exhibited an increased cytotoxicity (IC50 = 18.4 µM) and a stronger interaction with STAT3 (IC50 = 1.4 µM), leading to inhibition of its signaling pathway. Pt-3 was also evaluated in cell-based assays for its action on p53 expression and on STAT3 phosphorylation. In syngeneic murine Lewis lung carcinoma (LLC) implanted in C57BL/6 mice, Pt-3 showed a higher antitumor activity with fewer side effects than cisplatin.

Crystal structure of 3-(3-oxo-2,3,4,4a,5,6-hexa-hydro-benzo[h]cinnolin-2-yl)propionic acid.

The asymmetric unit of the title compound, C15H16N2O3, contains two independent mol-ecules, which present a different conformation of the carb-oxy-lic acid side chain [C-C-C-OH torsion angles = 65.3 (7) and -170.1 (5)°]. In both mol-ecules, the di-hydro-pyridazinone ring adopts a geometry inter-mediate between a twisted-boat and a half-chair conformation, while the central six-membered ring is almost in a half-boat conformation. In the crystal, mol-ecules are linked by O-H⋯Ok (k = ketone) hydrogen bonds, generating [01-1] chains. Aromatic π-π stacking contacts between the benzene and the di-hydro-pyridazinone rings [centroid-centroid distance [3.879 (9) Å] are also observed.

The influence of the substitution pattern on the molecular conformation of ureido-1,2,5-oxadiazoles, related to STAT3 inhibitors: chemical behavior and structural investigation.

Signal transducer and activator of transcription 3 (STAT3) is a protein constitutively activated by aberrant upstream tyrosine kinase activities in a broad spectrum of human solid and blood tumors. Therefore, the availability of drugs affecting STAT3 may have important therapeutic potential for the treatment of cancer. Pursuing our efforts in exploring the influence of the substitution pattern of the ureido 1,2,5-oxadiazole moiety on the molecular conformation, new compounds substituted at positions 3 and 4 on the furazane ring were synthesized. The inhibition properties vs. STAT3 of the novel compounds were evaluated in a dual-luciferase assay, using HCT-116 cells, and the results evidenced a moderate activity only for the compounds endowed with a planar arrangement. Crystallographic studies of the new derivatives were performed in order to evidence the peculiar chemical behavior and to evaluate how structural modulations affected the biological properties.

Signal transducer and activator of transcription 3 (STAT3): a promising target for anticancer therapy.

Signal transducer and activator of transcription 3 (STAT3) is an oncogenic protein whose inhibition is sought for the prevention and treatment of cancer. In this review, the validated therapeutic strategy to block aberrant activity of STAT3 in many tumor cell lines is evaluated by presenting the most promising inhibitors to date. The compounds are discussed in classes based on their different mechanisms of action, which are critically explained. In addition, their future clinical development as anticancer agents is considered. Furthermore, the efforts devoted to the comprehension of the structure-activity relationships and to the identification of the biological effects are brought to attention. The synthetic and technological approaches recently developed to overcome the difficulties in the obtainment of clinically suitable drugs are also presented.