title: Molecular aspects of the interaction of Hoechst-33258 with GC-rich promoter region of c-met.
abstract: The c-Met signaling pathway is one of the main regulators of cell proliferation, differentiation, apoptosis, and other cellular processes. As aberrant expression of c-Met has been implicated in tumor growth, invasion, and metastasis, c-Met is recognized as a promising target for cancer therapeutics. In continuation of our search for small molecules with anticancer properties, we investigated the binding of bis-benzimidazole derivative Hoechst-33258 to the promoter region 24RY, -142 to -119 (5'-GGGGCAGAGGCGGGAGGAAACGCG-3', 24R and its complement 5'-CGCGTTTCCTCCCGCCTCTGCCCC-3', 24Y), upstream to the transcriptional start site of the c-met gene. Strong complexation of duplex 24RY-Hoechst is revealed by a high binding constant K, 3.25 x 10(5) M(-1), with significant changes of Delta DeltaG (-10 kcal/mol), Delta DeltaH (-83 kcal/mol), Delta DeltaS (-241 cal/[mol K]), and melting temperature (DeltaT(m) = +8 degrees C). This is accompanied by bathochromic shift of 10 nm, 50% hypochromism at 340 nm, isobestic points at 302 and 369 nm in absorption spectra, and induced emission band at 465 nm in the fluorescence spectra of Hoechst. Molecular modeling data demonstrated that Hoechst binds to consecutive GGs in the minor groove of 24RY containing residues 12-17. Therefore, Hoechst-33258 can be a potential anticancer agent against malignancies associated with c-Met upregulation.
authors.affiliation: Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Garima
authors.initials: G
authors.lastname: Singhal
authors.forename: Moganty R
authors.initials: MR
authors.lastname: Rajeswari
mesh_terms: D006690:Bisbenzimidazole / Q000737:chemistry* / Q000378:metabolism*; D002942:Circular Dichroism; D020862:GC Rich Sequence; D006801:Humans; D008958:Models, Molecular; D011401:Promoter Regions, Genetic; D019859:Proto-Oncogene Proteins c-met / Q000737:chemistry* / Q000378:metabolism*; D013816:Thermodynamics
chemical_list: D019859:Proto-Oncogene Proteins c-met; D006690:Bisbenzimidazole