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.

Signal Transducer and Activator of Transcription 3 (STAT3) is a latent cytoplasmic protein overexpressed in various cancer cell lines. STAT3 participates in oncogenesis by stimulating cell proliferation and preventing apoptosis and it has been proven as a suitable target for anticancer therapy. In order to identify direct STAT3 inhibitors, we performed a binding assay on several previously synthesized 1,2,5-oxadiazole derivatives. Among them, compound MD77, N-[4-(4-chlorophenyl)-1,2,5-oxadiazol-3-yl]-4-(trifluoromethyl)benzamide, showed a good ability to bind the STAT3-SH2 domain in a dose-dependent manner (IC 50 ¼ 17.7 mM). Computational studies were carried out to investigate its binding mode. Moreover, compound MD77 showed a significant antiproliferative activity versus several tumor cell lines. On these bases, compound MD77 was selected as a lead for the future development of direct STAT3 inhibitors.

No abstract

STAT3 (Signal Transducer and Activator of Transcription 3) is a transcription factor constitutively activated by aberrant upstream tyrosine kinase activities in a broad spectrum of human solid and blood tumors, thus suggesting that its inhibition could represent an interesting molecular target for cancer therapy. With the aim to disclose novel scaffolds for compounds active on STAT3 the potential of the 1,2,5-oxadiazole ring was explored and several new compounds substituted at positions 3 and 4 of the heterocycle were synthesized. When tested in a dual-luciferase assay, using HCT-116 cells, some compounds showed a significant inhibition value towards STAT3. So, to give support to the biological results, modeling and crystallographic studies of representative terms of the new series were performed.

No abstract