Abstract 1436: Beta-caryophyllene regulates lipid biosynthesis in breast cancer cells
Authors: Mboge Mam Y. , Bullock Adam P. , O'Dennell Riley , Matthias John V. , Davila Julie A. , Frost Christopher J. , Frost Susan C. 
Published: August 2018

The search for therapeutic anti-cancer drugs has spanned both synthetic and natural products approaches, and notable success has been achieved from unique chemistries produced by plants. Early studies in E.coli showed that cyclic hydrocarbons, including terpenes, interact directly with biological membranes. Accumulation of hydrocarbons results in membrane swelling and increased membrane fluidity, both signs of cell stress. At biological temperatures, membrane fluidity is controlled by the saturation state of the acyl chains of fatty acids (primarily in phospholipids) and cholesterol content. Changes in either of these parameters leads to membrane remodeling which can affect membrane function. Terpenes are, themselves, precursors to complex sterols across all kingdoms of life. Beta-caryophylene (BCP), a bicyclic sesquiterpene, induces cell death across a variety of cancer cell types, although the mechanism(s) by which this occurs is not completely known. Our data show that BCP induces membrane permeability in breast cancer lines representing both ER-positive and triple negative phenotypes (TNBC), as measured by lactate dehydrogenase release from cells. We sought to understand this phenomenon by looking at changes in the transcriptome of treated cells compared to controls. We chose to examine cells exposed to hypoxia, rationalizing that this condition, in vivo, creates an aggressive phenotype, is associated with TNBC and drug-resistant (recurrent) breast cancers, and is an independent prognosticator for poor patient outcome. We isolated high quality RNA (RIN&gt;9) at the University of Florida. The Genomics Core at the University of Louisville prepared libraries and performed the sequencing run (Illumina NextSeq 500). This generated over 144 million 75bp reads that aligned to the human genome (96.3% alignment rate), or approximately 24 million reads per sample. As a first approach in data analysis, we selected differential expression based on the FDR adjusted p-values (q-values) &lt;0.05 (as determined by CuffDiff), and analyzed this gene set for pathway involvement using the reactome data base. Reactome also assesses FDR values for pathway analysis, and we selected pathway FDR &lt;0.05 providing the highest level of specificity. This search modality revealed an orchestrated up-regulation of lipid metabolism, including that of cholesterol biosynthesis. This is consistent with BCP-induced membrane remodeling. We have validated these results, not by PCR, but through protein expression and metabolic assays. Because these events occur at concentrations that are sub-cytotoxic, this potentially reveals a new mechanism underlying the development of drug resistance.

Citation Format: Mam Y. Mboge, Adam P. Bullock, Riley O'Dennell, John V. Matthias, Julie A. Davila, Christopher J. Frost, Susan C. Frost. Beta-caryophyllene regulates lipid biosynthesis in breast cancer cells [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 1436.