Datasets supporting the published article: DAXX-inducing phytoestrogens inhibit ER+ tumor initiating cells and delay tumor development

Recurrence of estrogen receptor (ER)-positive breast tumors despite definitive, curative-intent adjuvant therapy is thought to be due to enrichment of tumor initiating cells (TIC) during endocrine therapy (ET). Recently, it was identified that by antagonizing the ER, ET promotes the rapid degradation of the death-associated factor 6 (DAXX) protein, which is necessary and sufficient to potently inhibit TICs. Thus, the challenge is to identify an agent that increases DAXX protein levels to inhibit TICs and prevents proliferation of the tumor. Phytoestrogens (naringenin, resveratrol, genistein, apigenin, and quercetin), which are partial estrogens, were screened for DAXX protein expression, anti-TIC and anti-proliferative efficacy <i>in vitro</i> and<i> in vivo</i>. Specific DAXX-inducing phytoestrogens were also tested to assess selectivity towards ERα and/or ERβ.<br><b>Data access:</b> The raw and processed datasets supporting figures 1-9, generated during the current study, are publicly available in the figshare repository as part of this data record (<b>https://doi.org/10.6084/m9.figshare.12601724</b>). Additional datasets supporting supplementary figures 1-4, will be made available on reasonable request from the corresponding author Dr. Clodia Osipo, email address: <b>[e-mail]</b>. Uncropped Western blots are available as part of the supplementary figures.<br><b>Study approval</b>: All animal studies were approved by Loyola University Chicago’s Institutional Animal Care and Use Committee (IACUC). <br><b>Study aims and methodology</b>: In this study, the authors hypothesized that phytoestrogens may be sufficient to increase DAXX protein levels in an ERα/β-dependent manner without inducing total breast tumor cell proliferation. They tested the effects of a variety of phytoestrogens (naringenin, genistein, apigenin, resveratrol, and quercetin) on total cell proliferation of ER+ MCF-7 (wild-type p53) and T47D (mutant p53) cells, DAXX protein expression, and TIC survival <i>in vitro</i> and <i>in vivo</i>. They also tested if phytoestrogens may be more selective towards ERα or ERβ by using selective agonists or antagonists <i>in vitro.</i><br>Cell lines used: ER+ MCF-7 (wild-type p53) and T47D (mutant p53) cells.Patient-derived xenografts (PDXs) used: The PDX BCM-5097 was purchased from The Baylor College of Medicine. This primary breast tumor was originally derived from a female Caucasian patient with metastatic disease following pre-surgical docetaxel treatment. It is positive for both the ER and progesterone receptor (PR) and negative for overexpression of human epidermal growth receptor 2 (HER2).<br>The following techniques are described in more detail in the published article: RNA interference, Cycloheximide DAXX protein decay, Western blot analysis, Real time polymerase chain reaction (PCR), total cell proliferation, mammosphere forming assay, <i>ex vivo</i> analysis of TIC-survival, tumor initiating potential<i> in vivo</i>.<br><b>Data supporting the figures and supplementary figures in the published article:</b> All the datasets supporting figures 1-9 and supplementary figures 1-4, generated during the current study are listed in the data file <b>Peiffer et al.xlsx</b>. Datasets supporting figures 1-9 are in Excel (.xlsx), GraphPad (.pzf and .pzfx) and power point (.pptx) file format, and are part of this figshare data record.<br><b>Software needed to access data</b>: Files in. pzf can be opened by GraphPad Prism 4 or later. Files in .pzfx file format can be opened only by GraphPad Prism 5 or later.<br>