A dihydroindolizino indole derivative selectively stabilizes G-quadruplex DNA and down-regulates c-MYC expression in human cancer cells

Background: Telomeric and NHE III1 a c-MYC promoter region is abundant in guanine content and readily form G-quadruplex structures. Small molecules that stabilize G-quadruplex DNA were shown to reduce oncoprotein expression, initiate apoptosis and they may function as anticancer molecules. Methods: Electrospray ionization mass spectrometry, spectroscopy, isothermal titration calorimetry, Taq DNA polymerase stop assay, real time PCR and luciferase reporter assay. Cell migration assay to find out the effect of derivatives on normal as well as cancer cell proliferation. Results: Among three different dihydroindolizino indole derivatives, 4-cyanophenyl group attached derivative has shown maximum affinity, selective interaction and higher stability towards G-quadruplex DNA over dsDNA. Further, as a potential G-quadruplex DNA stabilizer, 4-cyanophenyl linked dihydroindolizino indole derivative was found to be more efficient in inhibiting in vitro DNA synthesis, c-MYC expression and cancer cell proliferation among human cancer cells. Conclusion: The present study reveals that dihydroindolizino indole derivative having 4-cyanophenyl group has potential to stabilize G-quadruplex DNA and exhibit anticancer activity. General significance: These studies are useful in the identification and synthesis of lead derivatives that will selectively stabilize G-quadruplex DNA and function as anticancer agents. (C) 2014 Elsevier B.V. All rights reserved.