Abstract 4510: Real-time imaging of tumor cells after exposure to NDC-1308 identifies the temporal order of cellular events leading to cancer cell death
Authors: Yarger James G. , Bittner Michael , Smith Edward , Nye Steven 
Published: June 2012

Recent evidence suggests that the growth of cancer cells is influenced by the estrogen receptor (ER) activity. We previously reported the discovery of Endece's family of small molecule ER-β agonists that will be used to treat human diseases, like cancer. Our lead candidate, NDC-1308, is cytotoxic to a broad range of human tumor cell lines (EC50 5-20 µM) and inhibits human tumor growth in mouse xenograft models. NDC-1308 binds with similar affinity to both ER-α and ER-β (70-100 nM), but activates ER-β nearly 5-fold more than ER-α. This finding is consistent with recent studies reported in the literature that show ER-β activation correlates with cell growth inhibition and ultimately cell death. Microarray analysis of three human tumor cell lines (A549-lung, SKOV-3-ovary, and Panc-1-pancreatic) treated with NDC-1308 (10-50 µM) for 24 hours caused significant effects on the regulation of genes associated with growth arrest and cell death pathways. For growth arrest, this includes the up-regulation of genes impacting the S and G2/M cell cycle checkpoints such as GADD45A (10-fold), the down-regulation of 21 key genes critical for chromosome replication (3-8 fold), and the up-regulation of nucleases such as GzmK (16-fold) and AEN (2-fold). For cell death, the up-regulation of genes within pro-apoptotic pathways includes BBC3 (4-fold) and GDF15 (12-fold), while the death receptor pathway gene TNFRSF10B (DR5) is up-regulated 5-fold. Since NDC-1308 treatment can lead to cancer cell death by simultaneously impacting cell cycle checkpoints, DNA damage and the apoptotic pathways, it holds great promise as an anticancer therapeutic. However, these studies have not identified the primary trigger event leading to NDC-1308 mediated cancer cell death. We therefore utilized real-time, live cell imaging with green fluorescent protein (GFP) reporters to better understand the initial mechanism of tumor cell death upon exposure to the drug. The tumor cells’ (A549 and Panc-1) response to NDC-1308 was compared to known DNA damaging agents, like ethyl methanesulfonate and hydrogen peroxide, which allowed for identification of well-characterized components of the pathways noted above. Utilizing a variety of different reporters provided information about the level of RNAs and intracellular localization of proteins known to be active in the proliferation and survival cellular pathways. As the measurements are non-destructive, a dense temporal profile of cellular elements that control the cells’ response to NDC-1308 and the other DNA damaging agents was produced. This profile will be presented along with our understanding of how NDC-1308 binding to estrogen receptors impacts cancer cell proliferation. Future studies will lead to the development of potential biomarkers for use in Phase 1 human clinical trials with NDC-1308.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4510. doi:10.1158/1538-7445.AM2011-4510