Publications by authors named "Michael Dame"

Background: Claudin-1 becomes overexpressed during the transformation of normal colonic mucosa to colorectal cancer (CRC).

Methods: Patient-derived organoids expressed clinically relevant target levels and genetic heterogeneity, and were established from human adenoma and normal colons. Colonoids were implanted orthotopically in the colon of immunocompromised mice.

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Models have been extensively used to investigate disease pathogenesis. Animal models are costly and require extensive logistics for animal care, and samples are not always suitable for different analytical techniques or to answer the research question. In vitro cell culture models are generally focused on recreating a specific characteristic of an organ and are limited to a single cell population that does not display the characteristic tissue architecture of the source organ.

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  • - Colorectal cancer is a significant health issue globally, with flat and subtle lesions often being overlooked in standard colonoscopies, which can lead to late diagnoses.
  • - Researchers created a preclinical model by implanting patient-derived adenoma colonoids into mice and used a fluorescent peptide targeting cMet to enhance the detection of these lesions through advanced imaging techniques.
  • - The study demonstrated that the NIR peptide was effective in labeling premalignant tissues without causing toxicity, providing a valuable method for early detection of colorectal cancer in human-derived models.
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Background: Hirschsprung disease (HSCR) is a congenital colonic aganglionosis. Many HSCR patients develop enterocolitis despite surgical resection. The pathophysiology of this inflammatory process is poorly understood.

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  • Transferrin receptor (TFRC) is crucial for iron uptake in cells, and its expression is unexpectedly high in iron-rich cancer cells, despite the risk of toxicity.
  • The study reveals that loss of the APC gene activates β-catenin, which increases TFRC levels in colorectal cancer, promoting iron accumulation that enhances β-catenin signaling.
  • Disrupting TFRC leads to reduced colonic iron and activates DNA damage responses, which may be targeted for new colorectal cancer treatments using iron chelation and DNA-damaging agents.
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Many esophageal diseases can arise during development or throughout life. Therefore, well-characterized in vitro models and detailed methods are essential for studying human esophageal development, homeostasis and disease. Here, we (1) create an atlas of the cell types observed in the normal adult human esophagus; (2) establish an ancestrally diverse biobank of in vitro esophagus tissue to interrogate homeostasis and injury; and (3) benchmark in vitro models using the adult human esophagus atlas.

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Human colonic organoids derived from biopsy or autopsy tissues are a vital tool to study mucosal homeostasis, model colonic diseases, and develop therapeutics. Rapid and reliable generation of knockout organoid lines from multiple donors enables analysis of specific gene functions. Here, we report protocols to produce colonic organoid knockout lines within 1 to 2 weeks using lentiviral delivery of CRISPR-Cas9, achieving knockout efficiency of 90% or greater.

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Background & Aims: TP53 mutations underlie Barrett's esophagus (BE) progression to dysplasia and cancer. During BE progression, the ubiquitin ligase (E3) RNF128/GRAIL switches expression from isoform 2 (Iso2) to Iso1, stabilizing mutant p53. However, the ubiquitin-conjugating enzyme (E2) that partners with Iso1 to stabilize mutant p53 is unknown.

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Sessile serrated adenomas (SSAs) are premalignant lesions driven by the BRAF mutation to give rise to colorectal cancers (CRCs). They are often missed during white light colonoscopy because of their subtle appearance. Previously, a fluorescently labeled 7mer peptide KCCFPAQ was shown to detect SSAs .

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  • Colorectal cancer (CRC) manipulates local iron handling, with hepcidin being activated in CRC, leading to increased tumor growth and size when ferroportin is deleted.
  • Mice lacking hepcidin in the colon show fewer and smaller tumors, while excessive intracellular iron worsens these parameters, indicating that iron is crucial for CRC progression.
  • The study highlights that CRC prioritizes iron for nucleotide production, and altering iron levels affects mitochondrial function and nucleotide synthesis, presenting potential targets for CRC treatments.
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The establishment of the small intestinal (SI) lineage during human embryogenesis ensures functional integrity of the intestine after birth. The chromatin dynamics that drive SI lineage formation and regional patterning in humans are essentially unknown. To fill this knowledge void, we apply a cutting-edge genomic technology to a state-of-the-art human model of early SI development.

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  • Aquamin, a natural multi-mineral product rich in calcium and magnesium, was studied to see if it could improve the colonic barrier in patients with ulcerative colitis (UC) by utilizing colonoid cultures from their biopsies.
  • The study involved incubating these colonoids with or without Aquamin for two weeks, analyzing changes in barrier proteins and structure using advanced microscopy and proteomic techniques.
  • Results showed some positive effects, including increased expression of differentiation-related proteins and tight junctions, as well as improved structural features, suggesting that Aquamin may enhance barrier function in UC-affected tissue.
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Cell line authentication is critical for preventing the use of mixed or misidentified cell lines in research. Current efforts include short tandem repeat (STR) analysis and PCR-based assays to detect mixed species cultures. Using PCR analysis with mouse-specific primers, we identified contaminating mouse DNA in growth factor conditioned medium (CM) derived from the L-WRN cell line (L-WRN CM), as well as in human organoid cultures maintained in the L-WRN CM.

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Leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5) has been identified as a marker of stem cells across multiple tissues. Lgr5-expressing cells are also regulators of tissue homeostasis and wound repair, and drivers of carcinogenic progression. The majority of information about Lgr5-expressing cells derives from genetically engineered mouse models.

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  • Human colonoids in low-calcium conditions (0.25 mM) can differentiate and express tight junction proteins, but don't express desmosomal proteins; adding calcium increases desmosomal protein expression and desmosome formation.
  • In transwell cultures, researchers assessed the impact of calcium on barrier integrity by measuring trans-epithelial electrical resistance (TEER), finding higher TEER values in low-calcium settings that improved with calcium.
  • The study concludes that while low calcium supports a permeability barrier, higher calcium levels enhance tissue cohesion and overall barrier function, highlighting the role of calcium intake in colonic health.
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Background & Aims: The enteroendocrine cell (EEC) lineage is important for intestinal homeostasis. It was recently shown that EEC progenitors contribute to intestinal epithelial growth and renewal, but the underlying mechanisms remain poorly understood. MicroRNAs are under-explored along the entire EEC lineage trajectory, and comparatively little is known about their contributions to intestinal homeostasis.

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  • Human astroviruses (HAstV) are viruses that mainly affect kids and older people, causing stomach problems.
  • Scientists found a new way to grow these viruses in human intestinal cells, which helps study how they infect people.
  • The research showed that a specific type of HAstV can infect different cell types and change how these cells respond to virus infections, which could help make treatments better.
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The presence of butyrogenic bacteria after the onset of acute GVHD associates with subsequent steroid-refractory GVHD or chronic GVHD. Butyrate inhibits human colonic stem cells from forming an intact epithelial monolayer.

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  • Chronic low-grade inflammation in fat tissue is linked to a higher risk of breast cancer, potentially due to changes in fat cell signals (adipokines) and inflammation-triggering immune cells (macrophages).
  • In a study, rats were fed either a Western diet or a fish oil diet, revealing that the fish oil diet led to a healthier balance of fatty acids and a shift towards anti-inflammatory fat signals.
  • The conditioned media from fish oil-fed rats showed a significantly lower ability to promote stem cell self-renewal compared to that from rats on a Western diet, suggesting that dietary changes could impact how fat tissues interact with breast stem cells.
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  • The study aimed to evaluate the effects of calcium and a multi-mineral product called Aquamin on the growth and differentiation of colonoid cultures from normal human colon tissue.
  • Researchers maintained colonoid cultures in low-calcium and higher calcium conditions, analyzing growth, morphology, and protein expression after two weeks.
  • Results showed that normal colonoids naturally differentiated even without calcium supplementation, while both calcium alone and Aquamin enhanced proteins related to tissue integrity, but had minimal additional effects on cell growth and differentiation.
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Models have been extensively used to investigate disease pathogenesis. Animal models are costly, require extensive logistics for animal care, and samples are not always suitable for different analytical techniques or to answer the research question. In vitro cell culture models are generally focused on recreating a specific characteristic of an organ, and are limited to a single cell population that does not display the characteristic tissue architecture of the source organ.

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Article Synopsis
  • In this study, researchers compared the effects of Aquamin versus calcium on human colon adenomas grown in lab cultures, finding that both improved cell differentiation compared to control.
  • Aquamin at a lower calcium concentration also promoted differentiation but was less effective, while specific proteins related to cell growth and differentiation were influenced more favorably by Aquamin than by calcium alone.
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  • Intestinal stem cells, marked by LGR5, are crucial for maintaining the intestine, but human studies are limited due to difficulty in isolating these cells.
  • Researchers created a repository of organoids from various colon tissues, analyzing them for genetic variants linked to colorectal cancer and employing techniques like immunohistochemistry.
  • The study revealed connections between LGR5 expression and tumor stage, along with correlations to specific genes related to colorectal cancer, contributing to methods and markers for researching human stem cells in health and disease.
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  • The study investigates the relationship between dietary iron intake and colorectal cancer (CRC), highlighting that iron's role in CRC development is not fully understood.
  • Researchers found that a protein called divalent metal transporter 1 (DMT1) is highly expressed in CRC, with its expression driven by stress-related factors.
  • The findings suggest that high iron levels activate a signaling network that promotes tumor growth, indicating that managing iron intake may have implications for CRC prevention and treatment.
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