Determining the Relationship between DNA Double Strand Breaks and Apoptosis: Implications for Cancer Therapy

Earley, Jillian

Student Work

Determining the Relationship between DNA Double Strand Breaks and Apoptosis: Implications for Cancer Therapy

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This project sought to better understand a known effect of chemotherapies, the DNA Double Strand Break, and its effect on cell functioning. Increasing amounts of Double Strand Breaks (DSBs) were induced in Retinal Pigment Epithelial cells using CRISPR and confirmed via yH2AX foci. The cellular response to these DSBs was explored through cell survival and apoptotic intensity. Apoptosis levels were indicated by quantifying nuclear abnormalities and active caspase-3/7 signals. Cells had decreased survival with increasing amounts of DSBs, and higher apoptotic levels in both nuclear morphology and caspase levels. Additionally, we analyzed cells deficient in hereditary breast and ovarian cancer gene, BRCA1, that are defective in DSB repair. Interestingly, BRCA1-deficient cell lines did not exhibit higher levels of cell demise nor apoptosis when compared to control lines. Likely buffering cell death in this context was Non-Homologous End Joining, a mechanism that functions in DSB repair and was found to be elevated in both cell lines following DSB inductions. Given that control and BRCA1-deficient cells respond similarly, loss of Homologous Recombination is not sufficient as a selective cancer therapy strategy following DSBs as induced here. Further exploration is needed to understand the complex cellular responses to DSB repair and the role of BRCA1 in DNA repair and cancer suppression.

This report represents the work of one or more WPI undergraduate students submitted to the faculty as evidence of completion of a degree requirement. WPI routinely publishes these reports on its website without editorial or peer review.

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