Methyl-Thiol-Bridged Oxadiazole and Triazole Heterocycles as Inhibitors of NF-κB in Chronic Myelogenous Leukemia Cells

Nuclear factor kappa beta (NF-κB) is a transcriptional factor that plays a crucial role in regulating cancer cell proliferation. Therefore, the inhibition of NF-κB activity by small molecules may be beneficial in cancer therapy. In this report, methyl-thiol-bridged oxadiazole and triazole heterocycles were synthesized via click chemistry and it was observed that the lead structure, 2-(((1-(3,4-dichlorophenyl)-1H-1,2,3-triazol-4-yl)methyl)thio)-5-(4-methoxybenzyl)-1,3,4-oxadiazole (4c), reduced the viability of MCF-7 cells with an IC(50) value of 7.4 µM. Compound 4c also caused concentration-dependent loss of cell viability in chronic myelogenous leukemia (CML) cells. Furthermore, compound 4c inhibited the activation of NF-κB in human CML cells as observed by nuclear translocation and DNA binding assays. Functionally, compound 4c produced PARP cleavage and also suppressed expression of Bcl-2/xl, MMP-9, COX-2, survivin, as well as VEGF, resulting in apoptosis of CML cells. Moreover, ChIP assay showed that compound 4c decreased the binding of COX-2 to the p65 gene promoter. Detailed in silico analysis also indicated that compound 4c targeted NF-κB in CML cells. In conclusion, a novel structure bearing both triazole and oxadiazole moieties has been identified that can target NF-κB in CML cells and may constitute a potential novel drug candidate.