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Transgenic expression of bacterial nitroreductase (NTR) enzymes sensitizes eukaryotic cells to prodrugs such as metronidazole (MTZ), enabling selective cell-ablation paradigms that have expanded studies of cell function and regeneration in vertebrates. However, first-generation NTRs required confoundingly toxic prodrug treatments to achieve effective cell ablation, and some cell types have proven resistant. Here we used rational engineering and cross-species screening to develop an NTR variant, NTR 2.0, which exhibits ~100-fold improvement in MTZ-mediated cell-specific ablation efficacy, eliminating the need for near-toxic prodrug treatment regimens. NTR 2.0 therefore enables sustained cell-loss paradigms and ablation of previously resistant cell types. These properties permit enhanced interrogations of cell function, extended challenges to the regenerative capacities of discrete stem cell niches, and novel modeling of chronic degenerative diseases. Accordingly, we have created a series of bipartite transgenic reporter/effector resources to facilitate dissemination of NTR 2.0 to the research community.

We lack tools to risk-stratify triple-negative breast cancer (TNBC). Our goal was to develop molecular tools to predict disease recurrence. Methylation array analysis was performed on 110 samples treated by locoregional therapy obtained from institutional cohorts. Discovered marker sets were then tested by Kaplan−Meier analyses in a prospectively collected TNBC cohort of 49 samples from the no-chemotherapy arms of IBCSG trials VIII and IX, and by logistic regression in a chemotherapy-treated cohort of 121 TNBCs from combined IBCSG trials and institutional repositories. High methylation was associated with shorter recurrence-free interval in the no-chemotherapy arm of the IBCSG studies, as well as in the chemotherapy-treated patients within the combined institutional and IBCSG chemotherapy cohorts (100 marker panel, p = 0.002; 30 marker panel, p = 0.05). Chromosome 19 sites were enriched among these loci. In conclusion, our hypermethylation signatures identify increased recurrence risk independent of whether patients receive chemotherapy.

Purpose:An unmet need in low-resource countries is an automated breast cancer detection assay to prioritize women who should undergo core breast biopsy and pathologic review. Therefore, we sought to identify and validate a panel of methylated DNA markers to discriminate between cancer and benign breast lesions using cells obtained by fine-needle aspiration (FNA).Experimental Design: Two case–control studies were conducted comparing cancer and benign breast tissue identified from clinical repositories in the United States, China, and South Africa for marker selection/training (N = 226) and testing (N = 246). Twenty-five methylated markers were assayed by Quantitative Multiplex-Methylation-Specific PCR (QM-MSP) to select and test a cancer-specific panel. Next, a pilot study was conducted on archival FNAs (49 benign, 24 invasive) from women with mammographically suspicious lesions using a newly developed, 5-hour, quantitative, automated cartridge system. We calculated sensitivity, specificity, and area under the receiver-operating characteristic curve (AUC) compared with histopathology for the marker panel.Results:In the discovery cohort, 10 of 25 markers were selected that were highly methylated in breast cancer compared with benign tissues by QM-MSP. In the independent test cohort, this panel yielded an AUC of 0.937 (95% CI = 0.900–0.970). In the FNA pilot, we achieved an AUC of 0.960 (95% CI = 0.883–1.0) using the automated cartridge system.Conclusions:We developed and piloted a fast and accurate methylation marker–based automated cartridge system to detect breast cancer in FNA samples. This quick ancillary test has the potential to prioritize cancer over benign tissues for expedited pathologic evaluation in poorly resourced countries.

Heterologously-expressed bacterial nitroreductase (NTR) enzymes sensitize eukaryotic cells to prodrugs such as metronidazole (MTZ), enabling selective cell ablation paradigms that have expanded studies of cell function and regeneration in vertebrate systems. However, first-generation NTRs require confoundingly toxic prodrug treatments (e.g. 10 mM MTZ) and some cell types have proven resistant. We used rational engineering and cross-species screening to develop a NTR variant, NTR 2.0, which exhibits ~100-fold improvement in MTZ-mediated cell-specific ablation efficacy. Toxicity tests in zebrafish showed no deleterious effects of prolonged MTZ treatments of ≤1 mM. NTR 2.0 therefore enables sustained cell loss paradigms and ablation of previously resistant cell types. These properties permit enhanced interrogations of cell function, extended challenges to the regenerative capacities of discrete stem cell niches, and enable modeling of chronic degenerative diseases. Accordingly, we have created a series of bipartite transgenic resources to facilitate dissemination of NTR 2.0 to the research community.

OBJECTIVES: Advanced ovarian clear cell carcinoma (OCCC) is associated with a survival disadvantage relative to ovarian serous carcinoma following platinum/taxane-based chemotherapy and optimal cytoreduction. Prostaglandin E2 (PGE2) contributes to disease progression through modulation of several G-protein coupled receptors (EP1-4) [Fig.1a]. The addition of upstream COX inhibition to platinum/taxane-based chemotherapy in the first-line phase II setting in ovarian cancer has been disappointing,a possibly due to compensatory upregulation of COX isoenzymes and negation of protective effects of EP1. Selective antagonism of EP4 may therefore pose a more rational strategy than global COX inhibition. Paclitaxel administration has been shown to upregulate components of the COX pathway.b Class III β-tubulin is a marker for paclitaxel resistance and is widely overexpressed in OCCC. The purpose of this study is to demonstrate that EP4 inhibition may overcome paclitaxel resistance in OCCC that overexpress class III β-tubulin. METHODS: Expression of EP4 receptor and class III β-tubulin was quantified using immunohistochemistry and Western blot in solid tissues and cell lines. Standard metabolic growth and migration assays were employed to test the effects of drug treatment (paclitaxel and EP4 inhibitors RQ-15986/AH-23848) with and without EP4 silencing using siRNA. RESULTS: OCCC overexpress class III β-tubulin/EP4 relative to normal ovary [Fig. 1b/c]. EP4 staining intensity was 2+ in 100% OCCC using an ovarian cancer tissue microarray (62 cores, 13% OCCC); this rate was only 26-56% among other histologies. EP4 inhibition reduces growth of paclitaxel-resistant cells [Fig. 1d]. Likewise, treatment with EP inhibitors [Fig.1 e-top] and silencing of EP4 resulted in reduced migration [Fig.1 e-bottom]. CONCLUSIONS: Selective antagonism of PGE2 through EP4 receptor inhibition may represent a powerful targeted therapy for paclitaxel-resistant OCCC. Further study including simultaneous treatment (EP4 inhibitor+paclitaxel) and larger samples sizes is required. REFERENCES: a Reyners et al. A randomized phase II study investigating the addition of the specific COX-2 inhibitor celecoxib to docetaxel plus carboplatin as first-line chemotherapy for stage IC to IV epithelial ovarian cancer, fallopian tube or primary peritoneal carcinomas: the DoCaCel study. Ann Oncol 2012; 23:2986-902. b Moos et al. Effects of taxol/taxotere on gene expression in macrophages: induction of the PGH synthetase-2 isoenzyme. J Immunol 1999;162:476-73. Citation Format: Dana M. Roque, Danielle Meir-Levi, Gautam G. Rao, Paul Staats, Amy Fulton, Jocelyn Reader. EP4 receptor antagonism in paclitaxel-resistant ovarian clear cell carcinomas that overexpress class III β-tubulin [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1179. doi:10.1158/1538-7445.AM2017-1179