Preferential binding of anti-cancer drug adriamycin to the Sp1 binding site in c-met promoter region: A spectroscopic and molecular modeling study

The c-met gene encodes a transmembrane glycoprotein receptor with tyrosine kinase activity and overexpression of MET receptor is found in a number of common human malignancies. Regulation of c-met oncogene expression in general can be controlled by several DNA binding anti-cancer drugs. Interaction of adriamycin with a short oligonucleotide (24RY), which is part of the positive regulatory element (−233 to −68) in c-met gene was studied using UV–Vis absorption and fluorescence spectroscopy, UV-thermal melting, and molecular modeling. Strong binding of adriamycin to 24RY (overall binding constant K, 1− 3 × 105 M−1) is thermodynamically favored and is accompanied by the following: a marked increase in the melting temperature of 24RY by +15 °C and ∼60% decrease in absorption at 480 nm, ∼80% quenching of fluorescence at 555 nm along with a blue shift of the λemimax to 522 nm of adriamycin. Present data reveals that adriamycin binds to ∼ 5 bp (GCGGG) of the Sp1 binding site in 24RY and thus competes with Sp1 binding to the promoter site which results in down-regulation of kinase. Therefore, targeting c-met is a promising approach as it is an attractive novel oncogene for cancer therapeutics.