Targeting RNA polymerase I with an oral small molecule CX-5461 inhibits ribosomal RNA synthesis and solid tumor growth

Denis Drygin, Amy Lin, Josh Bliesath, Caroline B Ho, Sean E O'Brien, Chris Proffitt, Mayuko Omori, Mustapha Haddach, Michael K Schwaebe, Adam Siddiqui-Jain, Nicole Streiner, Jaclyn E Quin, Elaine Sanij, Megan J Bywater, Ross Hannan, David Ryckman, Kenna Anderes, William G Rice

Research output: Contribution to journalArticleResearchpeer-review

416 Citations (Scopus)


Deregulated ribosomal RNA synthesis is associated with uncontrolled cancer cell proliferation. RNA polymerase (Pol) I, the multiprotein complex that synthesizes rRNA, is activated widely in cancer. Thus, selective inhibitors of Pol I may offer a general therapeutic strategy to block cancer cell proliferation. Coupling medicinal chemistry efforts to tandem cell- and molecular-based screening led to the design of CX-5461, a potent small-molecule inhibitor of rRNA synthesis in cancer cells. CX-5461 selectively inhibits Pol I-driven transcription relative to Pol II-driven transcription, DNA replication, and protein translation. Molecular studies demonstrate that CX-5461 inhibits the initiation stage of rRNA synthesis and induces both senescence and autophagy, but not apoptosis, through a p53-independent process in solid tumor cell lines. CX-5461 is orally bioavailable and demonstrates in vivo antitumor activity against human solid tumors in murine xenograft models. Our findings position CX-5461 for investigational clinical trials as a potent, selective, and orally administered agent for cancer treatment.
Original languageEnglish
Pages (from-to)1418 - 1430
Number of pages13
JournalCancer Research
Issue number4
Publication statusPublished - 2011

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