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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Alitretinoin, Animals, Antineoplastic Agents, Apoptosis, Carcinoma, Pancreatic Ductal, Cell Line, Tumor, Cell Movement, Cell Proliferation, Cellular Senescence, Disease Models, Animal, Disease Progression, Dose-Response Relationship, Drug, Gene Expression Regulation, Neoplastic, Humans, Isotretinoin, Mice, Mice, Mutant Strains, Pancreatic Neoplasms, Pancreatic Stellate Cells, Paracrine Communication, Proto-Oncogene Proteins, RNA Interference, Signal Transduction, Time Factors, Transcription, Genetic, Tretinoin, Wnt Proteins, beta Catenin.
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Does retinoic acid-induced pancreatic stellate cell quiescence reduce paracrine Wnt-β-catenin signaling to slow tumor progression? Context: Patients with pancreatic ductal adenocarcinoma are deficient in vitamin A, resulting in activation of pancreatic stellate cells (PSCs). We investigated whether restoration of retinol to PSCs restores their quiescence and affects adjacent cancer cells. PSCs and cancer cell lines (AsPc1 and Capan1) were exposed to doses and isoforms of retinoic acid (RA) in 2-dimensional and 3-dimensional culture conditions (physiomimetic organotypic culture). The effects of all-trans retinoic acid (ATRA) were studied in LSL-KrasG12D/+;LSL-Trp53R172H/+;Pdx-1-Cre mice, a model of human pancreatic ductal adenocarcinoma. After incubation with ATRA, PSCs were quiescent and had altered expression of genes that regulate proliferation, morphology, and motility; genes that encode cytoskeletal proteins and cytokines; and genes that control other functions, irrespective of culture conditions or dosage. In the organotypic model, and in mice, ATRA induced quiescence of PSCs and thereby reduced cancer cell proliferation and translocation of β-catenin to the nucleus, increased cancer cell apoptosis, and altered tumor morphology. ATRA reduced the motility of PSCs, so these cells created a "wall" at the junction between the tumor and the matrix that prevented cancer cell invasion. Restoring secreted frizzled-related protein 4 (sFRP4) secretion to quiescent PSCs reduced Wnt-β-catenin signaling in cancer cells and their invasive ability. Human primary and metastatic pancreatic tumor tissues stained strongly for cancer cell nuclear β-catenin but had low levels of sFRP4 (in cancer cells and PSCs).
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RA induces quiescence and reduces motility of PSCs, leading to reduced proliferation and increased apoptosis of surrounding pancreatic cancer cells. RA isoforms might be developed as therapeutic reagents for pancreatic cancer. Final Decision: yes