ABSTRACT
Targeting protein kinases (PKs) has been a promising strategy in treating cancer, as PKs are key regulators of cell survival and proliferation. Here in this study, we studied the ability of pyrimido[4',5':4,5]thieno(2,3-b)quinolines (PTQ) to inhibit different PKs by performing computational docking and in vitro screening. Docking studies revealed that 4-butylaminopyrimido[4',5':4,5]thieno(2,3-b)quinoline (BPTQ) has a higher order of interaction with the kinase receptors than other PTQ derivatives. In vitro screening confirms that BPTQ inhibits VEGFR1 and CHK2, with the IC50 values of 0.54 and 1.70 µmol/L, respectively. Further, cytotoxicity of BPTQ was measured by trypan blue assay. Treatment with BPTQ decreased the proliferation of HL-60 cells with an IC50 value of 12 µmol/L and induces apoptosis, as explicated by the fall in the mitochondrial membrane potential, annexin V labeling and increased expression of caspase-3. Taken together, these data suggest that BPTQ possess ability to inhibit PKs and to induce cell death in human promyelocytic leukemia cells.
ABSTRACT
PURPOSE: DNA intercalators are one of the interesting groups in cancer chemotherapy. The development of novel anticancer small molecule has gained remarkable interest over the last decade. In this study, we synthesized and investigated the ability of a tetracyclic-condensed quinoline compound, 4-butylaminopyrimido[4',5':4,5]thieno(2,3-b)quinoline (BPTQ), to interact with double-stranded DNA and inhibit cancer cell proliferation. METHODS: Circular dichroism, topological studies, molecular docking, absorbance, and fluorescence spectral titrations were employed to study the interaction of BPTQ with DNA. Cytotoxicity was studied by performing 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assay. Further, cell cycle analysis by flow cytometry, annexin V staining, mitochondrial membrane potential assay, DNA fragmentation, and western blot analysis were used to elucidate the mechanism of action of BPTQ at the cellular level. RESULTS: Spectral, topological, and docking studies confirmed that BPTQ is a typical intercalator of DNA. BPTQ induces dose-dependent inhibitory effect on the proliferation of cancer cells by arresting cells at S and G2/M phase. Further, BPTQ activates the mitochondria-mediated apoptosis pathway, as explicated by a decrease in mitochondrial membrane potential, increase in the Bax:Bcl-2 ratio, and activation of caspases. CONCLUSION: These results confirmed that BPTQ is a DNA intercalative anticancer molecule, which could aid in the development of future cancer therapeutic agents.
