Effects of the Ras-GEF inhibitor, BAY-293, on mitotic rate, cyclin levels and promoter activity in Tetrahymena species

Cancer is a complex disease characterized by uncontrolled growth resulting from genetic and epigenetic mutations. Receptor tyrosine kinases are a class of growth factor receptors whose signaling pathways are often dysregulated in cancer. The Ras GTPase plays a key transduction step in conveying the growth signal to the downstream kinases in the growth pathway, ultimately resulting in the phosphorylation of enzymes and transcription factors which help move the cell into S phase. In mammals, cyclin D1, a key cyclin responsible for the G1/S transition, is among the genes which are expressed in response to Ras signaling. Until recently, Ras was considered “undruggable”; however, several new drugs targeting Ras activity are in various stages of clinical testing. BAY-293 is a preclinical cancer drug that disrupts the communication of Ras with its activating guanine exchange factor (GEF), a protein commonly known as Sos. Tetrahymena thermophila are free-living protozoans that express homologs of Ras. Our previous studies have shown that BAY-293 reduces mitotic rate in Tetrahymena thermophila. Since we are currently unable to obtain the strain of T. thermophila on which we have worked in the past, we purchased Tetrahymena (unknown species) from Ward’s Biological and sequenced their mRNA in order to determine their species, which we believe to be T. pyriformis. Our current study aims to determine the effects of BAY-293 on mitosis levels in this Tetrahymena species, as well as to investigate the effects of BAY-293 on cyclin production and promoter activity as determined by H3K27ac levels.