The aureolic acid antibiotic mithramycin (MTM) binds selectively to GC-rich DNA sequences and blocks preferentially binding of proteins, like Sp1 transcription factors, to GC-rich elements in gene promoters. Genetic approaches can be applied to alter the MTM biosynthetic pathway in the producing microorganism and obtain new products with improved pharmacological properties. Here, we report on a new analog, MTM SDK, obtained by targeted gene inactivation of the ketoreductase MtmW catalyzing the last step in MTM biosynthesis. SDK exhibited greater activity as transcriptional inhibitor compared to MTM. SDK was a potent inhibitor of Sp1-dependent reporter activity and interfered minimally with reporters of other transcription factors, indicating that it retained a high degree of selectivity toward GC-rich DNA-binding transcription factors. RT-PCR and microarray analysis showed that SDK repressed transcription of multiple genes implicated in critical aspects of cancer development and progression, including cell cycle, apoptosis, migration, invasion and angiogenesis, consistent with the pleiotropic role of Sp1 family transcription factors. SDK inhibited proliferation and was a potent inducer of apoptosis in ovarian cancer cells while it had minimal effects on viability of normal cells. The new MTM derivative SDK could be an effective agent for treatment of cancer and other diseases with abnormal expression or activity of GC-rich DNA-binding transcription factors.
|Number of pages||14|
|Journal||Nucleic Acids Research|
|State||Published - 2006|
Bibliographical noteFunding Information:
We thank Dr D. Kardassis (Institute of Molecular Biology and Biotechnology, Heraklion, Greece), Dr R. Evans (The Salk Institute for Biological Studies, La Jolla, CA) and Dr G. Natoli (Institute for Research in Biomedicine, Bellinzona, Switzerland) for the gift of reporter and expression vectors. We acknowledge the support of the mass spectrometry and NMR core facilities of the University of Kentucky for the physicochemical characterization of SDK. This study was supported by Grant CA091901 from National Institutes of Health (to J.R.) and a grant from the Fondazione Ticinese per la Ricerca sul Cancro (to C.V.C.). The Open Access publication charges for this article were waived by Oxford University Press.
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