DNA is the molecular target for an array of antitumor and antimicrobial drugs, and the design and development of new drugs that target specific DNA secondary structures or sequences continues to be a challenge. Guanine-rich DNA sequences can form four-stranded secondary structures called G-quadruplexes, which represent alternative DNA structures that can potentially be targeted by small molecules. Thus, the stabilization of G-quadruplex structures in the promoter region of oncogenes is an emerging field in the design of anticancer drugs.

Particular emphasis has been focused on the c-myc oncogene, which plays a nontrivial role in many cellular events and the overexpression of the c-myc oncogene associated with a wide range of human cancers. Transcriptional control of c-myc has emerged as an attractive target for anticancer therapeutic strategies. By using a computer-aided, structure-based approach, C.-M. Che et al., University of Hong Kong, P.R. China, designed Pt^II complexes containing extended planar π-conjugated tridentate ligands with linked amine side-chains that effectively stabilize the c-myc G-quadruplex and down-regulate c-myc transcription. The complexes exhibit strong emission in the presence of G-quadruplex DNA but not duplex DNA, and thus have potential uses as luminescent probes.

• Structure-Based Design of Platinum(II) Complexes as c-myc Oncogene Down-Regulators and Luminescent Probes for G-Quadruplex DNA
  P.Wang, C-H. Leung, D.-L. Ma, S.-C. Yan, C.-M. Che,
  Chem. Eur. J. 2010, 16 (23).
  DOI: 10.1002/chem.201000167