Investigation of the Role of PTEN on EZH2 Expression

The PI3K/AKT/mTOR pathway is an intracellular signaling pathway involved with apoptosis, proliferation, and motility in eukaryotic cells. While PI3K propagates its signal by phosphorylating PIP2, PTEN is a tumor suppressor that regulates signal propagation by removing this phosphate group; a faulty PTEN then can cause the PI3K pathway to become overactive and induce cancer. EZH2 is an enzyme that acts as a gene silencer by trimethylating lysine 27 of histone 3, and is also expressed aberrantly in cancer cells. In this experiment, UM-UC-3 human bladder carcinoma cells were treated with an epidermal growth factor or LY249002 to either stimulate or inhibit PI3K expression. Western blots were then performed to investigate how expression of target genes changed in response to PI3K activation. Immunohistochemistry was also performed on PTEN-deficient mouse bladder samples to see how EZH2 expression varies across different cell types. It was found that PI3K upregulates PER1, RORA, and EZH2, and downregulates PPP2Ca. Our results illuminate how PI3K activity influences target gene expression and how they together determine cell behavior. These data will contribute to the ongoing effort to characterize genes affected by cancer, with the hopes of one day developing efficient, patient-specific treatments