Abstract LB-180: A human breast cancer 3D spheroid platform for microscopy based high throughput screening

Abstract

Abstract Breast cancer (BC) tumors originate in epithelial cells and rank second as a cause of cancer-related death in women (in 2020, ~270,000 women will be diagnosed, and 42,000 women will die from this disease in the USA). While important progress has been made on new treatments there is an urgent need to discover new therapeutics. We aim to discover therapeutics that elicits differentiation of BC tumor cells towards a phenotype that ceases proliferation and/or becomes more sensitive to therapeutic drugs. Also, since current high-throughput breast cancer drug discovery screens use conventional 2D cell cultures that do not fully represent the complex microenvironments of tumors in patients and often fail to predict clinical efficacy we are using 3D spheroids to better represent patient tumors. To identify potential therapeutic agents, we will quantify effects of test compounds on epigenetic markers (histone methylation/acetylation) within the nuclei of the tumor cells utilizing the Microscopic Imaging of Epigenetic Landscape (MIEL) assay developed by Alexey Terskikh's laboratory at SBP. The changes in epigenetics occur more rapidly than phenotypic changes resulting from differentiation which enables more rapid screening to identify potential therapeutic agents. Here we show that treating 2D cell cultures of the breast cancer cell line MCF7 with Tamoxifen, DPPE or E2 elicit changes in the epigenetic landscape. These epigenetic changes concur with increase in lipid droplet formation (a feature that is linked to milk-producing breast epithelium), and demonstrates that MIEL can be used as a readout of differentiation status. We are developing protocols to image breast cancer 3D spheroids on Vala Sciences' IC200 Structured Illumination Microscopy (IC200-SIM™ workstation). The SIM™ uses a multi-million array of micro-mirrors to achieve confocal resolution with rapid image acquisition, suitable for high throughput screening of spheroids cultured in the 96- or 384-well format. We envision that when developed, the MIEL-Breast Cancer Differentiation (MIEL-BCD) assay will be used to screen large chemical libraries (e.g., libraries with 100,000 different chemical entities) to identify compounds that promote differentiation of breast cancer cells to non-tumorigenic cells. Citation Format: Christine Gjerdrum Rines, Kara Gordon, Ranor Basa, Alyson Smith, Robert Oshima, Chen Farhy, Alexey Terskikh, Patrick McDonough, Jeffrey Price. A human breast cancer 3D spheroid platform for microscopy based high throughput screening [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-180.