Genetic Identification of Sulforaphane's Mechanism of Action in Yeast Cell Death

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DESCRIPTION (provided by applicant): Sulforaphane (SFN) is an isothiocyanate found in abundance in broccoli and broccoli sprouts that has proven to be an effective chemoprotective agent both in cell culture and in carcinogen-induced and genetic animal cancer models. Recently, several research groups have shown that SFN is able to induce two forms of programmed cell death (PCD) in mammalian cells known as apoptosis (PCD I) and autophagy (PCD II). Paradoxically, one laboratory has determined that mammalian cells can induce autophagy to protect themselves against SFN-induced apoptosis. However, how SFN induces autophagy remains unclear. To fill this knowledge gap, we are working to understand the mechanism of action of SFN in the induction of programmed cell death, especially of autophagy, using the budding yeast, Saccharomyces cerevisiae, as a model eukaryotic system. The proposed work is innovative, because it is the first time that sulforaphane's mechanism of action has been investigated in a genetically tractable model system. We would like to characterize a series of sulforaphane-resistant yeast mutants that we have isolated in our laboratory. These mutants should help us to identify the genetic pathway(s) involved in mediating SFN's mechanism of action in budding yeast cell death, genetic pathways that may also be involved in SFN's induction of cell death, especially of autophagy, in mammalian cells. We expect that our research program to have a positive impact because the identified genetic pathway(s) should provide new targets for pharmacological interventions that could enhance SFN's chemoprotective and chemotherapeutic effects as a clinical drug. The proposed research could also lead to the identification of mechanism-based biomarkers potentially useful in future clinical trials. Finally, in addition to expanding our knowledge base in cancer chemoprevention more generally and in sulforaphane's mechanism of action more specifically, funding the research described in this AREA R15 grant proposal will also allow my laboratory and our department here at Providence College to continue to train and to prepare talented undergraduate students for successful careers in the biomedical sciences. ) PUBLIC HEALTH RELEVANCE: Sulforaphane is a chemical ingredient found in abundance in broccoli and broccoli sprouts that has proven to be an effective anti-cancer drug both in cell culture and in animal models of cancer. It is not clear how this drug kills cancer cells though it is thought to be involved in triggering the process of cell suicide or programmed cell death. We would like to use yeast cells to discover how sulforaphane works. By identifying yeast mutants that are resistant to the drug, we hope to identify the genes involved in a cell's response to sulforaphane. We expect this research not only to help us better understand the process of cell suicide but also to enhance the drug's efficacy in clinical trials to treat cancer patients.