Dr. Krukenberg's background is in chemistry and biochemistry, and she completed her Ph.D. in Chemistry and Chemical Biology at the University of San Francisco, California. Under the supervision of Dr. David Agard, she worked on the structural and functional characterization of the molecular chaperone Hsp90. As a postdoctoral fellow at Harvard Medical School, she is training in cell biology under the guidance of Dr. Timothy Mitchison. Dr. Krukenberg's ultimate goal is to lead an academic research group focused on understanding the function and regulation of proteins in signaling pathways and their impacts on cancer. The NIH Pathway to Independence Award would provide necessary training in cell-based assays including microscopy, genomics, proteomics, and bioinformatics as well as in cancer pharmacology and the application of basic science to translational research. In pursuit of her goals, Dr. Krukenberg is investigating poly(ADP-ribose) polymerases (PARPs) and their relevance to cancer. PARPs catalyze the addition of poly(ADP-ribose) onto acceptor proteins involved in a variety of processes including the DNA damage response, inflammation, and transcription. PARPs also regulate the stability of a handful of proteins with diverse biological functions. Multiple PARP inhibitors are currently in clinical trials, either in combination with DN damaging agents or as single agents in cancers deficient in DNA damage repair (BRCA1/2 deficient cancers). Recent studies suggest that PARP inhibitors may have utility in treating some cancers independent of DNA damage. Understanding the broader roles of PARPs and pADPr may provide new therapeutic targets and expand the clinical uses of PARP inhibitors. Using an assay, which Dr. Krukenberg developed, for quantitating pADPr levels, she found that pADPr levels vary widely between breast cancer cells. Preliminary data suggests that this results from PARP1 hyperactivation in some cells.
The aims of this proposal are to 1) investigate the mechanism and functional consequences of PARP1 hyperactivation, including its role in drug sensitivity and to 2) explore the role of pADPr modification in regulating protein stability. Cancer signaling pathways regulated by pADPr will be elucidated, and the relationship between pADPr levels and chemotherapeutic responsiveness will be investigated. During the mentored phase (K99), mechanistic studies of PARP1 regulation and initial identification of pADPr modified targets in different cell lines will be completed. A survey of proteins whose stability is influenced by pADPr modification and an exploration of the relationship between pADPr levels and drug sensitivity will also be completed. If the data suggest pADPr levels have potential as a biomarker this exciting direction will be further developed in the independent phase with the initiation of additional clinical collaborations. Also during the independent phase, the biological consequences of pADPr modification on selected pathways will be investigated. Significant progress in understanding the biological function of pADPr and its role in cancer is anticipated. As a co-mentor, Dr. Judith Steen will provide mass spectrometry and proteomics expertise and instrumentation. As a contributor, Dr. Cyril Benes will provide cell lines for analysis along with data on their drug sensitivity and genotype. Dr. Benes will also provide critical expertise in cancer pharmacology. The proposed experiments will further define the biological roles and regulation of PARPs. This study will also determine the potential of pADPr levels in predicting drug sensitivity and identify possible new strategies for the use of PARP inhibitors in the clinic.

Public Health Relevance

Poly (ADP-ribose) polymerases (PARPs) play roles in many essential cellular processes including DNA damage repair and stress response. PARP inhibitors have shown clinical promise as single agents in treating a subset of cancers, particularly breast cancer, and in combination with other chemotherapeutics. The results of this study will provide insights into the roles of PARPs in cancer, paving the way for new combination therapies that may increase the efficacy of PARP inhibitors and increase the number of cancer types where PARP inhibitors are effective. The written critiques and criteria scores of individual reviewers are provided in essentially unedited form in the Critique section below. Please note that these critiques and criteria scores were prepared prior to the meeting and may not have been revised subsequent to any discussions at the review meeting. The Resume and Summary of Discussion section above summarizes the final opinions of the committee.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Career Transition Award (K99)
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Study Section
Subcommittee G - Education (NCI)
Program Officer
Schmidt, Michael K
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Harvard University
Schools of Medicine
United States
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Krukenberg, Kristin A; Kim, Sujeong; Tan, Edwin S et al. (2015) Extracellular poly(ADP-ribose) is a pro-inflammatory signal for macrophages. Chem Biol 22:446-452
Krukenberg, Kristin A; Jiang, Ruomu; Steen, Judith A et al. (2014) Basal activity of a PARP1-NuA4 complex varies dramatically across cancer cell lines. Cell Rep 8:1808-1818