Abstract 985: Development and validation of cell-based TFEB translocation assay in a high-content and high-throughput screening format

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Abstract Transcription factor EB (TFEB) is a master regulator of lysosomal gene expression and mitochondrial biogenesis. Autophagy is known to act as a double edged sword in cancer. Autophagy acts as a tumor suppressor during the tumorigenesis process but it also helps to sustain the survival of already transformed cancer cells. Lysosomes sit at the end of the autophagy pathway, which is critical to meet the needs of autophagy. Therefore, small molecules that inhibit TFEB-mediated lysosomal biogenesis and autophagic degradation may be helpful for inhibiting cancer cell growth and limiting cancer progression. On the other hand, small molecules that enhance TFEB-mediated lysosomal degradation may be used to prevent tumorigenesis. In order to identify compounds that modulate TFEB translocation, an image-based TFEB translocation assay was developed in a 1536-well plate format with a GFP-TFEB stable AML12 cell line, which is an immortalized mouse hepatocyte cell line. Torin 1, a known TFEB translocation inducer, was used as positive control in the study. Torin 1 increased TFEB nuclear translocation in a concentration dependent manner with an EC50 of 150nM. To optimize the assay condition, various cell densities per well and time courses were tested. To validate this assay, a group of 384 known anticancer compounds were screened at 11 concentrations ranging from 0.8 nM to 46 μM. From this screening, we identified 25 compounds that enhanced TFEB nuclear translocation with EC50s ranging from 2 nM to 12 μM. Several known and novel TFEB inducers were among these compounds. These results demonstrate that this high-content and high-throughput assay can be used to screen large numbers of chemicals and provide a robust in vitro system to identify TFEB agonists and antagonists, which may be used to either prevent (agonists) or treat (antagonist) cancer. Citation Format: Li Zhang, Ruili Huang, Wen Xing Ding, Menghang Xia. Development and validation of cell-based TFEB translocation assay in a high-content and high-throughput screening format [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 985.