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Background: The Androgen Receptor (AR) nuclear transcription factor is a therapeutic target for prostate cancer (PCa). Unfortunately, patients can develop resistance to AR-targeted therapies and progress to lethal disease, underscoring the importance of understanding the molecular mechanisms that underlie treatment resistance. Inflammation is implicated in PCa initiation and progression and we have previously reported that the inflammatory cytokine, . CC-BY-NC-ND 4.

In an effort to confirm previously reported linkages to psoriasis, we analyzed 942 affected sibling pairs (ASPs) from 710 pedigrees for 53 polymorphic microsatellites spanning 14 psoriasis candidate regions at an intermarker spacing of approximately 5 cM. Maximum LOD score (MLS) analysis of ASPs yielded allele sharing of 60% for markers within the major histocompatibility complex (MHC) (P=2 x 10(-14)), which yielded a gene-specific lambda(s) of 1.6. Across the remainder of the genome, the strongest evidence of allele sharing was obtained on chromosomes 16q (D16S3032; MLS=1.3; P=.007) and 10q22-q23 (D10S2327; MLS=1.1; P=.012). None of the remaining loci exceeded MLS=0.9, the value expected to occur by chance once in this study. In agreement with previous studies, strong linkage disequilibrium was also observed between psoriasis and the MHC (pedigree disequilibrium test P=3.9 x 10(-8) for D6S1014). Two psoriasis-associated MHC haplotypes were identified with the haplotype-based transmission/disequilibrium test. Analysis of only those families carrying either of these haplotypes significantly increased the chromosome 16q LOD score from 1.3 to 2.4 (P=.045). These results underscore the importance of the MHC in psoriasis and provide a rationale for more-detailed examination of candidate regions on chromosomes 16q and 10q.

Estrogen receptor α (ERα)low/− tumors are associated with breast cancer (BCa) endocrine resistance, where ERα low tumors show a poor prognosis and a molecular profile similar to triple negative BCa tumors. Interleukin‐1 (IL‐1) downregulates ERα accumulation in BCa cell lines, yet the cells can remain viable. In kind, IL‐1 and ERα show inverse accumulation in BCa patient tumors and IL‐1 is implicated in BCa progression. IL‐1 represses the androgen receptor hormone receptor in prostate cancer cells concomitant with the upregulation of the prosurvival, autophagy‐related protein, Sequestome‐1 (p62/SQSTM1; hereinafter, p62); and given their similar etiology, we hypothesized that IL‐1 also upregulates p62 in BCa cells concomitant with hormone receptor repression. To test our hypothesis, BCa cell lines were exposed to conditioned medium from IL‐1‐secreting bone marrow stromal cells (BMSCs), IL‐1, or IL‐1 receptor antagonist. Cells were analyzed for the accumulation of ERα, progesterone receptor (PR), p62, or the autophagosome membrane protein, microtubule‐associated protein 1 light chain 3 (LC3), and for p62‐LC3 interaction. We found that IL‐1 is sufficient to mediate BMSC‐induced ERα and PR repression, p62 and autophagy upregulation, and p62‐LC3 interaction in ERα+/PR+ BCa cell lines. However, IL‐1 does not significantly elevate the high basal p62 accumulation or high basal autophagy in the ERα−/PR− BCa cell lines. Thus, our observations imply that IL‐1 confers a prosurvival ERα−/PR− molecular phenotype in ERα+/PR+ BCa cells that may be dependent on p62 function and autophagy and may underlie endocrine resistance.

BACKGROUND: Diverse toxicants and mixtures that affect hormone responsive cells [endocrine disrupting chemicals (EDCs)] are highly pervasive in the environment and are directly linked to human disease. They often target the nuclear receptor family of transcription factors modulating their levels and activity. Many high-throughput assays have been developed to query such toxicants; however, single-cell analysis of EDC effects on endogenous receptors has been missing, in part due to the lack of quality control metrics to reproducibly measure cell-to-cell variability in responses. OBJECTIVE: We began by developing single-cell imaging and informatic workflows to query whether the single cell distribution of the estrogen receptor-a (ER), used as a model system, can be used to measure effects of EDCs in a sensitive and reproducible manner. METHODS: We used high-throughput microscopy, coupled with image analytics to measure changes in single cell ER nuclear levels on treatment with ∼ 100 toxicants, over a large number of biological and technical replicates. RESULTS:We developed a two-tiered quality control pipeline for single cell analysis and tested it against a large set of biological replicates, and toxicants from the EPA and Agency for Toxic Substances and Disease Registry lists. We also identified a subset of potentially novel EDCs that were active only on the endogenous ER level and activity as measured by single molecule RNA fluorescence in situ hybridization (RNA FISH). DISCUSSION: We demonstrated that the distribution of ER levels per cell, and the changes upon chemical challenges were remarkably stable features; and importantly, these features could be used for quality control and identification of endocrine disruptor toxicants with high sensitivity. When coupled with orthogonal assays, ER single cell distribution is a valuable resource for high-throughput screening of environmental toxicants.

Despite the availability of potent HER-targeted agents, de novo and acquired resistance is common and continues to pose a major challenge, especially in the advanced setting. Amassing evidence point to the importance of HER2 mutations, including the most common HER2 L755S mutation, in mediating anti-HER2 resistance. The HER2 L755S mutation, in particular, is observed to be enriched in metastatic lesions compared to primary breast tumors. The need for effective therapy to treat tumors harboring HER2 mutations prevails. We have previously reported that acquired resistance to lapatinib (L)-containing treatments, mediated by HER2 L755S, could be overcome by the recently FDA-approved irreversible pan-HER tyrosine kinase inhibitor (TKI) neratinib (N). While N has shown great promise in patients with HER2-mutant metastatic breast cancer, its efficacy is somewhat limited. More recently, tucatinib, a HER2-selective TKI, has been shown to be effective in HER2-positive (+) brain metastases. Its potency in the context of HER2 mutations, however, has not yet been fully studied. In this study, we used the HER2+ BT474-L resistant (LR) cells, harboring endogenous HER2 L755S mutation, and parental (P) cells to first determine whether tucatinib may be effective in overcoming resistance mediated by HER2 mutations. Our results showed that while N effectively inhibited the growth of LR cells, although at a dose higher than that needed to inhibit the growth of naïve P cells, tucatinib failed to inhibit the growth of LR cells. Our results suggest that HER2 L755S mutation may confer cross-resistance to tucatinib. To further study mechanisms of resistance to 2nd generation anti-HER2 agents, we recently developed cell models with acquired resistance to N, through long-term exposure of the BT474-P and LR cells to increasing doses of N. These cells were profiled by reverse phase protein array (RPPA) and western blot analysis, which revealed restoration of HER2 phosphorylation in the NR derivatives, despite being cultured in the continuous presence of N. Interestingly, RNA-seq analysis revealed the presence of HER2 L755S mutation in all the NR derivatives, but not in the P cells, suggesting that the reactivated HER2 signaling observed in NR cells could be attributed to the emergence/acquisition of HER2 L755S mutation. Furthermore, while the P cells were highly sensitive to tucatinib, L, and the monoclonal antibody trastuzumab (T), the NR derivatives were totally resistant to these agents, suggesting that N resistance may also confer cross-resistance to tucatinib, L, and T. Additional molecular characterization to examine differential gene expression and mutational profile of the resistant derivatives, as well as testing of novel anti-HER2 regimens and drug combinations targeting downstream mediators to overcome resistance, both in vitro and in vivo, is ongoing. Citation Format: Jamunarani Veeraraghavan, Ragini Mistry, Sarmistha Nanda, Vidyalakshmi Sethunath, Martin Shea, Tamika Mitchell, Meenakshi Anurag, Michael A. Mancini, Fabio Stossi, C. Kent Osborne, Mothaffar F. Rimawi, Rachel Schiff. HER2 L755S mutation is associated with acquired resistance to lapatinib and neratinib, and confers cross-resistance to tucatinib in HER2-positive breast cancer models [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 1911.

Gene transcription is an essential process in cell biology, and allows cells interpret and respond to internal and external cues. Traditional bulk population methods (Northern blot, PCR, and RNAseq) that measure mRNA levels lack the ability to provide information on cell-to-cell variation in responses. Precise single cell and allelic visualization and quantification is possible via single molecule RNA fluorescence in situ hybridization (smFISH). RNA-FISH is performed by hybridizing target RNAs with labeled oligonucleotide probes. These can be imaged in medium/ high throughput modalities, and, through image analysis pipelines, provide quantitative data on both mature and nascent RNAs, all at the single cell level. The fixation, permeabilization, hybridization and imaging steps have been optimized in our lab over many years using the model system described herein, which results in successful and robust single cell analysis of smFISH labeling. The main goal with sample preparation and processing is to produce high quality images characterized by a high signal-to-noise ratio to reduce false positives and provide data that are more accurate. Here we offer our protocol describing the pipeline from sample preparation to data analysis in conjunction with suggestions and optimization steps to tailor to specific samples.

Cell-to-cell variation of protein expression in genetically homogeneous populations is a common biological trait often neglected during analysis of high-throughput (HT) screens and is rarely used as a metric to characterize chemicals. We have captured single-cell distributions of androgen receptor (AR) nuclear levels after perturbations as a means to evaluate assay reproducibility and characterize a small subset of chemicals. AR, a member of the nuclear receptor family of transcription factors, is the central regulator of male reproduction and is involved in many pathophysiological processes. AR protein levels and nuclear localization often increase following ligand binding, with dihydrotestosterone (DHT) being the natural agonist. HT AR immunofluorescence imaging was used in multiple cell lines to define single-cell nuclear values extracted from thousands of cells per condition treated with DHT or DMSO (control). Analysis of numerous biological replicates led to a quality control metric that takes into account the distribution of single-cell data, and how it changes upon treatments. Dose–response experiments across several cell lines showed a large range of sensitivity to DHT, prompting us to treat selected cell lines with 45 Environmental Protection Agency (EPA)-provided chemicals that include many endocrine-disrupting chemicals (EDCs); data from six of the compounds were then integrated with orthogonal assays. Our comprehensive results indicate that quantitative single-cell distribution analysis of AR protein levels is a valid method to detect the potential androgenic and antiandrogenic actions of environmentally relevant chemicals in a sensitive and reproducible manner.