Apoptosis is a form of programmed cell death (PCD) that is essential in the removal of injured or dying cells, as well as harmful cells from the body (i.e.: cancer cells). This process can be induced following exposure to chemotherapeutic drugs and involves specific hallmarks such as a collapse of the mitochondrial membrane potential as well as the activation of cysteinyl proteases called caspases that lead to the orderly dismantling of the cell. Previous findings have shown that apoptosis is reversible in cultured cells if the inducer is washed away from the culture medium, wherein cells can be rescued via a process called anastasis. In this study, we investigated the kinetics of anastasis in Jurkat cells (a model human leukemic T cell line) following apoptosis induction with the chemotherapeutic drug camptothecin. Camptothecin is a potent apoptosis inducing drug which blocks DNA replication by inhibiting topoisomerase I. Caspase activity, mitochondrial membrane potential (MMP), cell metabolic rate (MR) and viability were quantified with specific fluorescent substrates using flow cytometry. Our results indicate that untreated Jurkat cells expressed low caspase activity levels and high MMP, MR and viability, whereas apoptotic Jurkat cells treated with camptothecin for 16 hours expressed high caspase activity levels but decreased MMP, MR and cell viability. Upon removal of camptothecin from the culture medium, Jurkat cells gradually increased MMP, MR and viability over a 72 hour period. Collectively, our data strongly suggests that Jurkat cells can undergo anastasis (apoptosis reversibility) and gradually regain metabolic activity and function.
Acknowledgements: I appreciate my funding from the Student Research Grant. Also, thank you to my thesis advisor, Professor Robert Lauzon, for the time and guidance during the research.