Project description:ABSTRACT: Obesity is responsible for decreased overall survival for breast cancer patients. Here, we describe the generation, characterization and application of a novel murine mammary tumor initiating cell model (M-Wnt) that recapitulates the claudin-low subtype of human breast cancer and permits the study of TIC’s in wild-type, immunocompetent mice. M-Wnt cells readily form mammospheres in suspension culture, express markers consistent with epithelial-to-mesenchymal transition (EMT), and generate claudin-low mammary tumors when as few as 50 cells are orthotopically injected. Using the M-Wnt cell lines in tandem with a more basal-like epithelial breast cancer cell line, E-Wnt, we found that diet induced obesity significantly downregulates epithelial markers, such as E-cadherin, and upregulates mesenchymal markers including fibronectin, N-cadherin, SNAIL, Oct-4, and TGF-b. This reveals a previously unidentified link between energy balance and EMT. The ability of calorie restriction (CR) to reverse EMT, upregulate epithelial markers and downregulate mesenchymal markers indicates the plasticity of the TICs, as well as the potential importance of lifestyle modifications as cancer prevention strategies. 28 array samples
Project description:<p>Sample collection can significantly affect measurements of relative lipid concentrations in cell line panels, hiding intrinsic biological properties of interest between cell lines. Most quality control steps in lipidomic data analysis focus on controlling technical variation. Correcting for the total amount of biological material remains an additional challenge for cell line panels. Here, we investigated how we can normalize lipidomic data acquired from multiple cell lines to correct for differences in sample biomass.</p><p>We studied how commonly used data normalization and transformation steps during analysis influenced the resulting lipid data distributions. We compared normalization by biological properties such as cell count or total protein concentration, to statistical and data-based approaches, such as median, mean or probabilistic quotient-based normalization and used intraclass correlation to estimate how similarity between replicates changed after normalization.</p><p>Normalizing lipidomic data by cell count improved similarity between replicates, but only for a study with cell lines with similar morphological phenotypes. For cell line panels with multiple morphologies collected over a longer time, neither cell count nor protein concentration was sufficient to increase the similarity of lipid abundances between replicates of the same cell line. Data-based normalizations increased these similarities, but also created artifacts in the data caused by a bias towards the large and variable lipid class of triglycerides. This artifact was reduced by normalizing for the abundance of only structural lipids. We conclude that there is a delicate balance between improving the similarity between replicates and avoiding artifacts in lipidomic data and emphasize the importance of an appropriate normalization strategy in studying biological phenomena using lipidomics.</p><p><br></p><p>__________________________________________</p><p><br></p><p>Rewiring of lipid metabolism is a hallmark of cancer, supporting tumor growth, survival, and therapy resistance. However, lipid metabolic heterogeneity in breast cancer remains poorly understood. In this study, we systematically profiled the lipidome of 52 breast cancer cell lines using liquid chromatography-mass spectrometry to uncover lipidomic signatures associated with tumor subtype, proliferation, and epithelial-to-mesenchymal (EMT) state. A total of 806 lipid species were identified and quantified across 21 lipid classes. The main lipidomic heterogeneity was associated with the EMT state, with lower sphingolipid, phosphatidylinositol and phosphatidylethanolamine levels and higher cholesterol ester levels in aggressive mesenchymal-like cell lines compared to epithelial-like cell lines. In addition, cell lines with higher proliferation rates had lower levels of sphingomyelins and polyunsaturated fatty acid (PUFA) side chains in phospholipids. Next, changes in the lipidome over time were analyzed for three fast-proliferating mesenchymal-like cell lines MDA-MB-231, Hs578T, and HCC38. Triglycerides decreased over time, leading to a reduction in lipid droplet levels, and especially PUFA-containing triglycerides and -phospholipids decreased during proliferation. These findings underscore the role of EMT in metabolic plasticity and highlight proliferation-associated lipid dependencies that may be exploited for therapeutic intervention. In conclusion, our study reveals that EMT-driven metabolic reprogramming is a key factor in lipid heterogeneity in breast cancer, providing new insights into tumor lipid metabolism and potential metabolic vulnerabilities.</p>
Project description:PURPOSE: To provide a detailed gene expression profile of the normal postnatal mouse cornea. METHODS: Serial analysis of gene expression (SAGE) was performed on postnatal day (PN)9 and adult mouse (6 week) total corneas. The expression of selected genes was analyzed by in situ hybridization. RESULTS: A total of 64,272 PN9 and 62,206 adult tags were sequenced. Mouse corneal transcriptomes are composed of at least 19,544 and 18,509 unique mRNAs, respectively. One third of the unique tags were expressed at both stages, whereas a third was identified exclusively in PN9 or adult corneas. Three hundred thirty-four PN9 and 339 adult tags were enriched more than fivefold over other published nonocular libraries. Abundant transcripts were associated with metabolic functions, redox activities, and barrier integrity. Three members of the Ly-6/uPAR family whose functions are unknown in the cornea constitute more than 1% of the total mRNA. Aquaporin 5, epithelial membrane protein and glutathione-S-transferase (GST) omega-1, and GST alpha-4 mRNAs were preferentially expressed in distinct corneal epithelial layers, providing new markers for stratification. More than 200 tags were differentially expressed, of which 25 mediate transcription. CONCLUSIONS: In addition to providing a detailed profile of expressed genes in the PN9 and mature mouse cornea, the present SAGE data demonstrate dynamic changes in gene expression after eye opening and provide new probes for exploring corneal epithelial cell stratification, development, and function and for exploring the intricate relationship between programmed and environmentally induced gene expression in the cornea. Keywords: other
Project description:Introgressed variants from other species can be an important source of genetic variation because they may arise rapidly, can include multiple mutations on a single haplotype, and have often been pretested by selection in the species of origin. Although introgressed alleles are generally deleterious, several studies have reported introgression as the source of adaptive alleles-including the rodenticide-resistant variant of Vkorc1 that introgressed from Mus spretus into European populations of Mus musculus domesticus. Here, we conducted bidirectional genome scans to characterize introgressed regions into one wild population of M. spretus from Spain and three wild populations of M. m. domesticus from France, Germany, and Iran. Despite the fact that these species show considerable intrinsic postzygotic reproductive isolation, introgression was observed in all individuals, including in the M. musculus reference genome (GRCm38). Mus spretus individuals had a greater proportion of introgression compared with M. m. domesticus, and within M. m. domesticus, the proportion of introgression decreased with geographic distance from the area of sympatry. Introgression was observed on all autosomes for both species, but not on the X-chromosome in M. m. domesticus, consistent with known X-linked hybrid sterility and inviability genes that have been mapped to the M. spretus X-chromosome. Tract lengths were generally short with a few outliers of up to 2.7 Mb. Interestingly, the longest introgressed tracts were in olfactory receptor regions, and introgressed tracts were significantly enriched for olfactory receptor genes in both species, suggesting that introgression may be a source of functional novelty even between species with high barriers to gene flow.
Project description:We have generated and employed reversible and irreversible EMT models of murine breast cancer cells to identify the key players establishing cell state transitions during a reversible and an irreversible EMT. We demonstrate that the Mbd3/NuRD complex, involving histone deacetylases (HDACs) and Tet2 hydroxylase, acts as an epigenetic block in epithelial-mesenchymal plasticity. These epigenetic modifiers keep breast cancer cells in a stable mesenchymal state, and their pharmacological inhibition or genetic ablation leads to a mesenchymal-epithelial transition (MET) and represses primary tumor growth and metastasis formation of highly aggressive, mesenchymal breast cancer cells.