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Evaluating In Vitro DNA Damage Using Comet Assay
Published on: October 11, 2017
Decreased DNA Damage and Improved p53 Specificity of RITA Analogs
Yue Zhan1,2, Xiaolei Zhou1, Sylvain Peuget1
1Department of Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.
Abstract:
Reactivation of p53 tumor-suppressor function by small molecules is an attractive strategy to defeat cancer. A potent p53-reactivating molecule RITA, which triggers p53-dependent apoptosis in human tumor cells in vitro and in vivo, exhibits p53-independent cytotoxicity due to modifications by detoxification enzyme Sulfotransferase 1A1 (SULT1A1), producing a reactive carbocation. Several synthetic modifications to RITA's heterocyclic scaffold lead to higher energy barriers for carbocation formation. In this study, we addressed the question whether RITA analogs NSC777196 and NSC782846 can induce p53-dependent apoptosis without SULT1A1-dependent DNA damage. We found that RITA analog NSC782846, but not NSC777196, induced p53-regulated genes, targeted oncogene addiction, and killed cancer cells upon p53 reactivation, but without induction of DNA damage and inhibition RNA pol II. Our results might demonstrate a method for designing more specific and potent RITA analogs to accelerate translation of p53-targeting compounds from laboratory bench to clinic.
Insights
The RITA analog NSC782846 reactivates tumor suppressor p53 to kill cancer cells without causing DNA damage. This discovery offers a path toward developing safer, more effective p53-targeting cancer therapies.
Area of Science:
- Oncology
- Molecular Biology
- Medicinal Chemistry
Background:
- Reactivating the p53 tumor suppressor is a promising cancer treatment strategy.
- The small molecule RITA induces p53-dependent apoptosis but also causes DNA damage via SULT1A1 modification.
- Synthetic modifications aim to create RITA analogs with improved specificity and reduced toxicity.
Purpose of the Study:
- To investigate if RITA analogs NSC777196 and NSC782846 can induce p53-dependent apoptosis without SULT1A1-mediated DNA damage.
- To evaluate the potential of these analogs as targeted cancer therapeutics.
Main Methods:
- Synthesis and chemical modification of RITA analogs.
- Assessing p53-dependent apoptosis induction in cancer cells.
- Measuring DNA damage and RNA polymerase II inhibition.
- Analyzing p53-regulated gene expression.
Main Results:
- NSC782846, but not NSC777196, induced p53-regulated genes and cancer cell death.
- NSC782846 achieved this via p53 reactivation without causing DNA damage or inhibiting RNA polymerase II.
- This suggests a dissociation between p53 reactivation and genotoxicity for NSC782846.
Conclusions:
- NSC782846 demonstrates a potential for p53-dependent cancer cell killing without genotoxicity.
- This study provides a framework for designing next-generation RITA analogs with enhanced specificity.
- Findings may accelerate the clinical translation of p53-targeting cancer drugs.
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