Identification and characterization of small molecule inhibitors of the calcium-dependent S100B-p53 tumor suppressor interaction.

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TitleIdentification and characterization of small molecule inhibitors of the calcium-dependent S100B-p53 tumor suppressor interaction.
Publication TypeJournal Article
Year of Publication2004
AuthorsMarkowitz, J, Chen, I, Gitti, R, Baldisseri, DM, Pan, Y, Udan, R, Carrier, F, Mackerell, AD, Weber, DJ
JournalJ Med Chem
Volume47
Issue21
Pagination5085-93
Date Published2004 Oct 07
ISSN0022-2623
KeywordsAntineoplastic Agents, Binding Sites, Calcium, Cell Line, Tumor, Databases, Factual, Holoenzymes, Humans, Magnetic Resonance Spectroscopy, Melanoma, Models, Molecular, Molecular Conformation, Nerve Growth Factors, Pentamidine, Protein Binding, S100 Calcium Binding Protein beta Subunit, S100 Proteins, Spectrometry, Fluorescence, Tumor Suppressor Protein p53
Abstract

The binding of S100B to p53 down-regulates wild-type p53 tumor suppressor activity in cancer cells such as malignant melanoma, so a search for small molecules that bind S100B and prevent S100B-p53 complex formation was undertaken. Chemical databases were computationally searched for potential inhibitors of S100B, and 60 compounds were selected for testing on the basis of energy scoring, commercial availability, and chemical similarity clustering. Seven of these compounds bound to S100B as determined by steady state fluorescence spectroscopy (1.0 microM < or = K(D) < or = 120 microM) and five inhibited the growth of primary malignant melanoma cells (C8146A) at comparable concentrations (1.0 microM < or = IC(50) < or = 50 microM). Additionally, saturation transfer difference (STD) NMR experiments confirmed binding and qualitatively identified protons from the small molecule at the small molecule-S100B interface. Heteronuclear single quantum coherence (HSQC) NMR titrations indicate that these compounds interact with the p53 binding site on S100B. An NMR-docked model of one such inhibitor, pentamidine, bound to Ca(2+)-loaded S100B was calculated using intermolecular NOE data between S100B and the drug, and indicates that pentamidine binds into the p53 binding site on S100B defined by helices 3 and 4 and loop 2 (termed the hinge region).

DOI10.1021/jm0497038
Alternate JournalJ. Med. Chem.
PubMed ID15456252
Grant ListCA 095200 / CA / NCI NIH HHS / United States
GM 58888 / GM / NIGMS NIH HHS / United States
S10 RR016812 / RR / NCRR NIH HHS / United States
F30 NS 043916 / NS / NINDS NIH HHS / United States
S10 RR015741 / RR / NCRR NIH HHS / United States
R01 GM058888 / GM / NIGMS NIH HHS / United States