Development of Novel Bis(indolyl)-hydrazide Hydrazone Derivatives as Potent Microtubule-Targeting Cytotoxic Agents against A549 Lung Cancer Cells

摘要

The biological significance of microtubules makes them a validated target of cancer therapy. In this study, we have utilized indole, an important pharmacological scaffold, to synthesize novel bis(indolyl)-hydrazide-hydrazone derivatives (NMK-BH compounds) and recognized NMK-BH3 as the most effective one in inhibiting A549 cell proliferation and assembly of tissue-purified tubulin. Cell viability experiments showed that NMK-BH3 inhibited proliferation of human lung adenocarcinoma (A549) cells, normal human lung fibroblasts (WI38) and peripheral blood mononuclear cells (PBMC) with IC50 values of similar to 2, 48.5, and 62 mu M, respectively. Thus, the relatively high cytotoxicity of NMK-BH3 toward lung carcinoma (A549) cells over normal lung fibroblasts (WI38) and PBMC confers a therapeutic advantage of reduced host toxicity. Flow cytometry, Western blot, and immunofluorescence studies in the A549 cell line revealed that NMK-BH3 induced G2/M arrest, mitochondrial depolarization, and apoptosis by depolymerizing the cellular interphase and spindle microtubules. Consistent with these observations, study in cell free system revealed that NMK-BH3 inhibited the microtubule assembly with an IC50 value of similar to 7.5 mu M. The tubulin ligand interaction study using fluorescence spectroscopy indicated that NMK-BH3 exhibited strong and specific tubulin binding with a dissociation constant of similar to 1.4 mu M at a single site, very close to colchicine site, on beta-tubulin. Collectively, these findings explore the cytotoxic potential of NMK-BH3 by targeting the microtubules and inspire its development as a potential candidate for lung cancer chemotherapy.