B.A. Dartmouth College 1984;
Ph.D. University of California, Berkeley 1989;
NIH Postdoctoral Fellow, ETH-Zurich, Switzerland
Drug Development Targeting Transcription Drivers in Cancer
Dysregulation of gene expression is a hallmark of all cancers. It is critical for self-renewal and chemo-resistance of cancer cells which contributes to the inability to completely eradicate cancer cells, thereby leading to relapse. The specific gene expression program that confers these properties derives from the aberrant activity of specific transcription factors which are drivers of disease. Clearly, the most direct and effective approach to alter this gene expression program is to directly target the activity of the transcription factors driving the disease. There are numerous examples of such transcription factor drivers in cancer such as fusion proteins of RUNX1 and CBFβ in leukemia, fusion proteins of ERG in prostate cancer and Ewing’s sarcoma, ETV-1 in melanoma, other members of the Ets family of transcription factors in a variety of different cancers, etc. Transcription factors have traditionally been viewed as “undruggable” due to the need to target more challenging protein-protein or protein nucleic acid interactions through which these proteins act. There are still relatively few examples of such agents for cancer treatment, with the MDM2-p53 inhibitors being one example of such an agent that has progressed to the clinic. We are exploring several unique approaches to target this important class of proteins for drug development.
a. Illendula A, Pulikkan JA, Zong H, Grembecka J, Xue L, Sen S, Zhou Y, Boulton A, Kuntimaddi A, Gao Y, Rajewski RA, Guzman ML, Castilla LH, Bushweller JH. Chemical biology. A small-molecule inhibitor of the aberrant transcription factor CBFβ-SMMHC delays leukemia in mice. Science. 2015 Feb 13;347(6223):779-84. PubMed PMID: 25678665; PubMed Central PMCID: PMC4423805.
b. Illendula A, Gilmour J, Grembecka J, Tirumala VSS, Boulton A, Kuntimaddi A, Schmidt C, , Wang L, John A. Pulikkan, Hongliang Zong, Mahmut Parlak, Cem Kuscu, Anna Pickin, Yunpeng Zhou, Yan Gao Y, Mishra L, Adli M, Castilla LH, Rajewski RA, Janes KA, Guzman ML, Bonifer C, and Bushweller JH. Small Molecule Inhibitor of CBFb-RUNX Binding for RUNX Transcription Factor Driven Cancers. EBioMedicine. 2016 8: 117-131. Pubmed PMID: ; PubMed Central PMCID: .
c. Pulikkan JA, Hegde M, Belaghzal H, Illendula A, Yu J, Ahmed H, O’Hagan K, Ou J, Muller-Tidow C, Wolfe SA, Zhu LJ, Dekker J, Bushweller JH, Castilla LH. CBFβ-SMMHC inhibition leads to alteration of chromatin dynamics at MYC distal enhancers and abrogation of inv(16) leukemia. Cell. June 28, 2018 174(1):172-186. PubMed PMID: 29958106. [PMC Journal – in process]
Structure/Function Studies of Transcription Factor Drivers in Cancer
Our lab is fundamentally interested in understanding, from a structural and biophysical perspective, the functioning of proteins involved in regulating transcription, particularly those involved in the dysregulation associated with the development of cancer. Structural and functional characterization of the native forms of these proteins and their relevant complexes via NMR spectroscopy, X-ray crystallography, and a variety of other techniques provides a baseline of understanding. Subsequent characterization of the oncoprotein forms then provides a detailed understanding of the molecular mechanism of oncogenesis associated with altered forms of these proteins. Such knowledge leads to novel avenues for the design of therapeutic agents to treat the cancers associated with these particular oncoproteins. A long-term focus has been structural studies of a novel transcription factor referred to as the core-binding factor (CBF). This heterodimeric protein is essential for hematopoietic development. Gene translocations associated with the genes coding for the two subunits of CBF produce novel fusion proteins which have been implicated as playing a role in more than 30% of acute leukemias. We have carried out extensive structural and functional studies of the oncoprotein forms of the two subunits of CBF that are associated with leukemia. We have extended these studies to the MLL protein, a key epigenetic regulator that is the target of chromosomal translocations in leukemia which are particularly poor prognosis.
a. Cierpicki T, Risner LE, Grembecka J, Lukasik SM, Popovic R, Omonkowska M, Shultis DD, Zeleznik-Le NJ, Bushweller JH. Structure of the MLL CXXC domain-DNA complex and its functional role in MLL-AF9 leukemia. Nat Struct Mol Biol. 2010 Jan;17(1):62-8. PubMed PMID: 20010842; PubMed Central PMCID: PMC2908503.
b. Kuntimaddi A, Achille NJ, Thorpe J, Lokken AA, Singh R, Hemenway CS, Adli M, Zeleznik-Le NJ, Bushweller JH. Degree of recruitment of DOT1L to MLL-AF9 defines level of H3K79 Di- and tri-methylation on target genes and transformation potential. Cell Rep. 2015 May 5;11(5):808-20. PubMed PMID: 25921540; PubMed Central PMCID: PMC4426023.
Structural Studies of Membrane Proteins
A third focus for the lab is the application of solution NMR methods to the structure determination of membrane proteins. The vast majority of drug targets are membrane-embedded proteins. This class of proteins has presented significant challenges for structure determination by any method. We determined the structure of the 4 TM enzyme DsbB by solution NMR which established a paradigm for tackling this class of proteins by NMR. We recently completed the structure determination and mechanistic studies of the 6 TM membrane transporter CcdA.
a. Zhou Y, Cierpicki T, Jimenez RH, Lukasik SM, Ellena JF, Cafiso DS, Kadokura H, Beckwith J, Bushweller JH. NMR solution structure of the integral membrane enzyme DsbB: functional insights into DsbB-catalyzed disulfide bond formation. Mol Cell. 2008 Sep 26;31(6):896-908. PubMed PMID: 18922471; PubMed Central PMCID: PMC2622435.
b. Zhou Y and Bushweller JH. Solution Structure and Elevator Mechanism of the Membrane Electron Transporter CcdA. Nat Struct Mol Biol. 2018 25(2):163-169. Pubmed PMID: ; PubMed Central PMCID: .
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