Biology subjects

Polemi, K. M.

Publications and source records attributed to Polemi, K. M..

7 recordsLinked to original sources

bioRxiv2026

Exposure to p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) Perturbs Cell State and Stem Cell Markers and Induces an Epidermal Phenotype in Human Breast Cells

Breast cancer is the second leading cause of cancer deaths in U.S. women. Endocrine disruptors, such as the DDT metabolite DDE, are environmental factors linked to breast cancer risk. Emerging evidence shows that during carcinogenesis, cells reacquire stem cell traits and exhibit phenotypic plasticity. In these phenotypically plastic states, breast cells transition between phenotypes, for example, from epithelial to mesenchymal (EMT) phenotypes, or from luminal to basal. Discovering how environmental factors alter cell phenotype may be a critical step in preventing and treating breast cancer. We applied a novel high-content imaging method for the evaluation of expression of stemness and cell state markers (ALDH1A3, CD44, CD24, KRT8, and KRT14) and evaluated these markers after introducing environmentally relevant concentrations of DDE (25 nM to 25 M) to non-tumorigenic MCF10A breast epithelial cells grown in 3D anchorage independent conditions. After identifying surprisingly profound cell state alterations, including a loss of KRT8 and KRT14 expression, by 25 M DDE exposure, we used transcriptomic profiling along with pharmaceutical and genetic knockdown approaches to characterize the molecular mechanisms by which DDE exposure modulates breast epithelial cell state. Keratinization and formation of the cornified envelope were biological pathways upregulated with a maximum fold change of 360.47. We identify DLX3 as a transcription factor which is inducible by DDE exposure and is also highly upregulated in human breast cancers, reflecting a novel mechanism by which environmental exposures may promote cellular plasticity and breast carcinogenesis.

pharmacology and toxicology↗

bioRxiv2026

Exploring the Influence of Chemical Exposures in Breast Cancer Disparities: High-Throughput Transcriptomic Analysis in Normal Breast Cells from Diverse Donors

Racial disparities in the incidence of, and mortality from, aggressive breast cancers are a pressing public health issue. Many factors have been investigated in these inequities; however, the role of toxicant exposures is not well characterized. We and others have identified substantial inequities in chemical biomarker concentrations by race. The goal of this study was to test the hypothesis that exposure to these chemicals is linked to biological changes relevant to aggressive breast cancers, such as dysregulation of the Hallmarks of Cancer. We used high throughput transcriptomic profiling of normal primary human breast epithelial cells from diverse donors (n=6) to test effects of 8 chemicals (cadmium, lead, arsenic, copper, PFNA, BPA, BPS, p,p-DDE) with documented exposure disparities by race/ethnicity across 3 concentrations (100nM, 1{micro}M, 10{micro}M). Across chemicals, we identified that pathways related to cell cycle regulation and protein secretion were commonly affected. Through bioinformatic estimation of cell type proportions, we found that metals like lead and cadmium induced cell-type shifts, consistent with the dysregulated cellular plasticity cancer hallmark. Lead and arsenic response genes were enriched for genes associated with poor breast cancer survival in the Cancer Genome Atlas. Integrating concentration-response modeling and chemical biomonitoring data, BPA, p,p-DDE, copper, and lead elicited expression changes at concentrations relevant to the US population. Finally, we identified substantial interindividual heterogeneity in response to organic compounds, but less so in metals. These findings highlight the value of high-throughput transcriptomics as a New Approach Methodology (NAM) in quantifying how common exposures may impact aggressive breast cancer associated biological processes.

pharmacology and toxicology↗

bioRxiv2025

Environmentally Relevant Lead Exposure Alters Cell Morphology and Expression of Neural Hallmarks During SH-SY5Y Neuronal Differentiation

Lead (Pb) continues to be a public health burden, in the US and around the world, and yet the effects of historical and current exposure levels on neurogenesis are not fully understood. Here we examine the effects of a range of environmentally relevant Pb concentrations (0.16M, 1.26M, and 10M Pb) relative to control on neural differentiation in the SH-SY5Y cell model. Pb exposure began on Day 5 and continued throughout differentiation at Day 18. We assessed morphological measures related to neurogenesis at several time points during this process, including the expression of proteins key in neural differentiation ({beta}-tubulin III and GAP43), cell number and size, as well as the development of neurites. The bulk of detectable changes occurred with 10M Pb exposure, most notably that of {beta}-tubulin III and GAP43 expression. Effects with the 0.16M and 1.26M Pb exposure conditions increased as differentiation progressed, with significant reductions in cell and nuclear size as well as the number and length of neural projections by Day 18. Best benchmark concentration (BMC) analysis revealed many of these metrics to be susceptible to levels of Pb at or below historically relevant levels. This work highlights the disruption of neurite formation and protein expression as potential new mechanisms by which environmentally relevant Pb exposure impacts neurogenesis and morphology and perturb cognitive health throughout the life course.

neuroscience↗

bioRxiv2024

Environmentally Relevant Lead Exposure Impacts Gene Expression in SH-SY5Y Cells Throughout Neuronal Differentiation

Lead (Pb) causes learning and memory impairments, but the molecular effects of continuous, environmentally relevant levels of exposure on key neurodevelopmental processes are not fully characterized. Here we examine the effects of a range of environmentally relevant Pb concentrations (0.16M, 1.26M, and 10M Pb) relative to control on neural differentiation in the SH-SY5Y cell model. Pb exposure began on differentiation day 5 and was continuous for remaining days, after which we assessed the transcriptome via RNA sequencing at several time points. The bulk of detected changes in gene expression occurred with the 10M Pb condition. Interestingly, changes associated with the lower two exposures were differentiation stage-specific, with aberrant expression of several genes (e.g., COL3A1, HMOX1, and CCL2) observed during differentiation on days 9, 12, and 15 in both the 0.16M and 1.26M Pb conditions, and which disappeared by the time differentiation concluded on day 18. We observed six co-expression clusters of genes during differentiation, and 10uM Pb significantly perturbed two clusters, one involved in cell cycling and DNA repair and the other in protein synthesis. Benchmark concentration analysis identified many genes affected by levels of Pb at or below the current US standard (3.5g/dL) and these genes were enriched for pathways including stress responses, DNA repair, misfolded protein response, mitosis, and neurotransmitter production. This work highlights potential new mechanisms by which environmentally relevant concentrations of Pb impact gene expression throughout neural differentiation and result in long-lasting implications for neural health and cognition.

pharmacology and toxicology↗

bioRxiv2024

Applying Cell Painting in Non-Tumorigenic Breast Cells to Understand Impacts of Common Chemical Exposures

There are a substantial number of chemicals to which individuals in the general population are exposed which have putative, but still poorly understood, links to breast cancer. Cell Painting is a high-content imaging-based in vitro assay that allows for rapid and unbiased measurements of the concentration-dependent effects of chemical exposures on cellular morphology. We optimized the Cell Painting assay and measured the effect of exposure to 16 human exposure relevant chemicals, along with 21 small molecules with known mechanisms of action, for 48 hours in non- tumorigenic mammary epithelial cells, the MCF10A cell line. Through unbiased imaging analyses using CellProfiler, we quantified 3042 morphological features across approximately 1.2 millio n cells. We used benchmark concentration modeling to quantify significance and dose-dependent directionality to identify morphological features conserved across chemicals and find features that differentiate the effects of toxicants from one another. Benchmark concentrations were compared to chemical exposure biomarker concentration measurements from the National Health and Nutrition Examination Survey to assess which chemicals induce morphological alterations at human-relevant concentrations. Morphometric fingerprint analysis revealed similar phenotypes between small molecules and prioritized NHANES-toxicants guiding further investigation. A comparison of feature fingerprints via hypergeometric analysis revealed significant feature overlaps between chemicals when stratified by compartment and stain. One such example was the similarities between a metabolite of the organochlorine pesticide DDT (p,p-DDE) and an activator of canonical Wnt signaling CHIR99201. As CHIR99201 is a known Wnt pathway activator and its role in -catenin translocation is well studied, we studied the translocation of -catenin following p-p DDE exposure in an orthogonal high-content imaging assay. Consistent with activation of Wnt signaling, low dose p,p-DDE (25nM) significantly enhances the nuclear translocation of -catenin. Overall, these findings highlight the ability of Cell Painting to enhance mode-of-action studies for toxicants which are common exposures in our environment but have previously been incompletely characterized with respect to breast cancer risk.

pharmacology and toxicology↗

bioRxiv2022

High Throughput Transcriptomics to Understand Chemical Drivers of Racial Disparities in Breast Cancer

BackgroundThe impact of chemical exposures on breast cancer progression is poorly characterized and may influence the development of more severe and aggressive subtypes. ObjectivesThere is a suite of toxicants, including metals, pesticides, and personal care product compounds, which are commonly detected at high levels in US Center for Disease Controls National Health and Nutrition Examination Survey (NHANES) chemical biomarker screens. To characterize the impact of these toxicants on breast cancer pathways, we performed high throughput dose-response transcriptomic analysis of toxicant exposed breast cells. MethodsWe treated non-tumorigenic mammary epithelial cells, MCF10A, with 21 chemicals at four doses (25nM, 250nM, 2.5{micro}M, 25{micro}M) for 48 hours. We conducted RNA-sequencing for these 408 samples, adapting the PlexWell plate-based RNA-sequencing method to analyze changes in gene expression resulting from these exposures. For each chemical, we calculated gene and biological pathway specific benchmark doses using BMDExpress2, identifying differentially expressed genes and generating the best fit benchmark dose models for each gene. We employed enrichment testing to test whether each chemicals upregulated or downregulated genes were over-represented in a biological process or pathway. We contextualized benchmark doses relative to human population biomarker concentrations in NHANES. ResultsOverall, significant changes in gene expression varied across doses of each chemical and benchmark dose modeling revealed dose-responsive alterations of thousands of different genes. Comparison of benchmark data to NHANES chemical biomarker concentrations indicated an overlap between actual exposure levels and levels sufficient to cause a gene expression response. Enrichment and cell deconvolution analyses showed benchmark dose responses correlated with changes in cancer and breast cancer related pathways, including induction of basal-like characteristics for some chemicals, including p,p-DDE, lead, copper, and methyl paraben. DiscussionThese analyses revealed that these 21 chemicals induce significant changes in pathways involved in breast cancer initiation and progression at human exposure relevant doses.

cancer biology↗

bioRxiv2019

Pesticide exposure and adverse health effects associated with farm work in Northern Thailand

Article SummaryO_ST_ABSObjectivesC_ST_ABSTo assess pesticide exposure and understand the resultant health effects of agricultural workers in Northern Thailand. DesignCross-sectional study. SettingThe entirety of this study was completed in Chiang Rai, Thailand, at Mae Fah Luang University, Chiang Rai Prachanukroh hospital, the village leaders home, and the community center. Participants97 men between the ages of 22-76 years of age; 70 were conventional farmwokers and 27 did not report any prior farm or pesticide spraying. Primary Outcome MeasuresWe quantified exposure to pesticides including chlorpyrifos, methomyl, and metalaxyl, by air sampling and liquid chromatography/mass spectrometry. We estimated differences in self-reported health outcomes, complete blood counts, cholinesterase activity, and serum/urine calcium and creatinine concentrations at baseline between farmworkers and comparison workers, and after pesticide spraying in farmworkers only. Secondary Outcome MeasuresWe quantified ResultsNone of the farmworkers wore standardized PPE for the concentrated chemicals they were working with. Methomyl, ethyl chlorpyrifos, and metalaxyl were detected air samples in varying amounts. When it came to reporting confidence in the ability to handle personal problems, only 43% of farmworkers reported feeling confident; which reflects higher stress levels in comparison to 78% of comparison workers (p = 0.028). Farmworkers also had significantly lower monocyte counts (p=0.01), serum calcium (p=0.01), red blood count (p=0.01), white blood cell count (p=0.04), and butyrylcholinesterase activity (p<0.0001), relative to comparison workers. After adjusting for BMI, age, and smoking, methomyl air concentrations were associated with a decrease in farmworker acetylcholinesterase activity (beta= -0.327, p =0.016). ConclusionsFarmworkers blood analytes, acetylcholinesterase, and self-reported symptoms differed from comparison workers. Improving PPE use presents a likely route for preventive intervention in this population. Strengths and Limitations: O_LIThe US Occupational Safety and Health Administration (OSHA) generally recommends testing for baseline cholinesterase levels after not working with organophosphates for at least 30 days(1). However, this was not capable for our study, and baseline cholinesterase measurements may not actually represent a true baseline measurement due to their overlapping work schedules C_LIO_LIThis pilot study did not take multiple baseline measurements, and the one baseline that was taken was likely taken before the OSHA recommended guideline of 30 days since pesticide use. C_LIO_LIOur study also focused on workplace sampling at a time when the specific farm of interest was expected to be spraying chlorpyrifos, therefore the study results show an over-representation of chlorpyrifos. C_LIO_LIThis is the first study of its type that took a mixed-methods approach using survey, biomarker, and workplace observation data to analyze farmworker pesticide health effects in comparison to other workers in Northern Thailand. C_LIO_LIThis pilot study is one of the larger studies on farmworker chemical exposures in Thailand. These data can inform the methods for future global occupational health research on farmworkers. C_LIO_LIThis study is very generalizable to farmworkers in LMIC and Thailand. C_LI

pharmacology and toxicology↗