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Published on: January 31, 2018
Single cell resolution in vivo imaging of DNA damage following PARP inhibition
Katherine S Yang1, Rainer H Kohler1, Matthieu Landon2
1Center for Systems Biology, Massachusetts General Hospital, 185 Cambridge St, CPZN 5206, Boston, MA 02114.
Abstract:
Targeting DNA repair pathways is a powerful strategy to treat cancers. To gauge efficacy in vivo, typical response markers include late stage effects such as tumor shrinkage, progression free survival, or invasive repeat biopsies. These approaches are often difficult to answer critical questions such as how a given drug affects single cell populations as a function of dose and time, distance from microvessels or how drug concentration (pharmacokinetics) correlates with DNA damage (pharmacodynamics). Here, we established a single-cell in vivo pharmacodynamic imaging read-out based on a truncated 53BP1 double-strand break reporter to determine whether or not poly(ADP-ribose) polymerase (PARP) inhibitor treatment leads to accumulation of DNA damage. Using this reporter, we show that not all PARP inhibitor treated tumors incur an increase in DNA damage. The method provides a framework for single cell analysis of cancer therapeutics in vivo.
Insights
A new imaging tool tracks DNA damage in single cancer cells. This reveals that not all tumors treated with poly(ADP-ribose) polymerase (PARP) inhibitors show increased DNA damage, offering insights into cancer drug efficacy.
Area of Science:
- Cancer Research
- Molecular Biology
- Pharmacology
Background:
- Targeting DNA repair pathways is a key cancer treatment strategy.
- Current methods for assessing drug efficacy in vivo, like tumor shrinkage or biopsies, have limitations in providing single-cell resolution or correlating pharmacokinetics with pharmacodynamics.
- Understanding drug effects at the single-cell level is crucial for optimizing cancer therapeutics.
Purpose of the Study:
- To develop a novel single-cell in vivo imaging method to assess DNA damage.
- To determine if poly(ADP-ribose) polymerase (PARP) inhibitor treatment consistently increases DNA damage in tumors.
- To establish a framework for real-time, single-cell analysis of cancer drug responses.
Main Methods:
- Development of a truncated 53BP1 double-strand break reporter system for in vivo imaging.
- Utilizing the reporter to visualize and quantify DNA damage accumulation at the single-cell level.
- Administering poly(ADP-ribose) polymerase (PARP) inhibitors to tumor-bearing models and analyzing DNA damage response.
Main Results:
- The established reporter system successfully enabled single-cell pharmacodynamic imaging in vivo.
- Demonstrated that not all tumors treated with PARP inhibitors exhibited a measurable increase in DNA damage.
- Highlighted variability in DNA damage accumulation within tumors following PARP inhibitor treatment.
Conclusions:
- The developed imaging readout provides a powerful tool for single-cell analysis of cancer therapeutics.
- The findings challenge the assumption of uniform DNA damage induction by PARP inhibitors across all treated tumors.
- This approach facilitates a more nuanced understanding of drug efficacy and guides personalized cancer treatment strategies.
