Abstract 3547: Properties of lipid rafts in two epigenetically distinct subtypes of the oncogenic cell-line SW13

Abstract

Abstract The epithelial SW13 cancer cell line has two naturally occurring well-defined cell subtypes. The SW13(Vim-) has a phenotype that resembles typical epithelial tumors, displaying increased growth and proliferation with a low level of invasiveness. The SW13(Vim+) subtype has a mesenchymal-like phenotype, commonly associated with more invasive and metastatic states of epithelial cancers. SW13(Vim-) can be converted to a pseudo SW13(Vim+) phenotype when treated with histone deacetylase inhibitors (HDACi). This model is used to study the epigenetic phenotypic differences between tumor-like cancer cells and cells that display a more metastatic phenotype. Gene chip data obtained from the SW13 treated and untreated cells displays differential expression in many genes, specifically genes for cellular membrane proteins and genes involved in cholesterol, sphingolipid, and GPI-anchored protein metabolism; all of which are essential components of lipid rafts. Additionally, recent improved outcomes noted in patients using statin drugs further implicates that cholesterol plays a role in cancer progression, although the mechanism for this improvement is not well understood. This suggests lipid rafts are a candidate for a physical structure that manifests the differential effect of cholesterol perturbations in cancer phenotypes. We hypothesize that lipid raft protein composition is distinctly different between the two SW13 cell subtypes, and that the differences in the composition of lipid rafts may play a role in the unique oncogenic phenotypes of the two subtypes. Utilizing low-temperature detergent-resistant lipid raft isolation techniques, western blotting, and mass spectrometry we investigate protein composition differences between the two SW13 cell subtypes. Cholesterol assays are applied to assess the distribution and total cholesterol content of each SW13 subtype, this also provides translational confirmation of the gene chip data obtained from the subtypes. Cholesterol depletion techniques utilizing cyclodextrin for acute disruption and simvastatin for chronic disruption are being implemented to perturb lipid rafts and observe their role in the oncogenic phenotypes of the SW13 cell subtypes. Specifically, metastatic qualities are measured after lipid raft and cholesterol perturbations. Initial findings support differential cholesterol representation in the two SW13 cell subtypes. Potential findings may explain a mechanism in which cholesterol perturbations are capable of decreasing metastasis and improving the outcome of patients with epithelial cancers. Citation Format: Luis Espejo, Kathryn J. Leyva, Elizabeth E. Hull. Properties of lipid rafts in two epigenetically distinct subtypes of the oncogenic cell-line SW13 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3547.