Endoderm Jagged induces liver and pancreas duct lineage in zebrafish.

Liver duct paucity is characteristic of children born with Alagille Syndrome (ALGS), a disease associated with JAGGED1 mutations. Here, we report that zebrafish embryos with compound homozygous mutations in two Notch ligand genes, jagged1b (jag1b) and jagged2b (jag2b) exhibit a complete loss of canonical Notch activity and duct cells within the liver and exocrine pancreas, whereas hepatocyte and acinar pancreas development is not affected. Further, animal chimera studies demonstrate that wild-type endoderm cells within the liver and pancreas can rescue Notch activity and duct lineage specification in adjacent cells lacking jag1b and jag2b expression. We conclude that these two Notch ligands are directly and solely responsible for all duct lineage specification in these organs in zebrafish. Our study uncovers genes required for lineage specification of the intrahepatopancreatic duct cells, challenges the role of duct cells as progenitors, and suggests a genetic mechanism for ALGS ductal paucity.The hepatopancreatic duct cells connect liver hepatocytes and pancreatic acinar cells to the intestine, but the mechanism for their lineage specification is unclear. Here, the authors reveal that Notch ligands Jagged1b and Jagged2b induce duct cell lineage in the liver and pancreas of the zebrafish.

Expansion of prominin-1-expressing cells in association with fibrosis of biliary atresia.

UNLABELLED: Biliary atresia (BA), the most common cause of end-stage liver disease and the leading indication for pediatric liver transplantation, is associated with intrahepatic ductular reactions within regions of rapidly expanding periportal biliary fibrosis. Whereas the extent of such biliary fibrosis is a negative predictor of long-term transplant-free survival, the cellular phenotypes involved in the fibrosis are not well established. Using a rhesus rotavirus-induced mouse model of BA, we demonstrate significant expansion of a cell population expressing the putative stem/progenitor cell marker, PROMININ-1 (PROM1), adjacent to ductular reactions within regions of periportal fibrosis. PROM1positive (pos) cells express Collagen-1α1. Subsets of PROM1pos cells coexpress progenitor cell marker CD49f, epithelial marker E-CADHERIN, biliary marker CYTOKERATIN-19, and mesenchymal markers VIMENTIN and alpha-SMOOTH MUSCLE ACTIN (αSMA). Expansion of the PROM1pos cell population is associated with activation of Fibroblast Growth Factor (FGF) and Transforming Growth Factor-beta (TGFß) signaling. In vitro cotreatment of PROM1-expressing Mat1a-/- hepatic progenitor cells with recombinant human FGF10 and TGFß1 promotes morphologic transformation toward a myofibroblastic cell phenotype with increased expression of myofibroblastic genes Collagen-1α1, Fibronectin, and α-Sma. Infants with BA demonstrate similar expansion of periportal PROM1pos cells with activated Mothers Against Decapentaplegic Homolog 3 (SMAD3) signaling in association with increased hepatic expression of FGF10, FGFR1, and FGFR2 as well as mesenchymal genes SLUG and SNAIL. Infants with perinatal subtype of BA have higher tissue levels of PROM1 expression than those with embryonic subtype. CONCLUSION: Expansion of collagen-producing PROM1pos cells within regions of periportal fibrosis is associated with activated FGF and TGFß pathways in both experimental and human BA. PROM1pos cells may therefore play an important role in the biliary fibrosis of BA.

Risk of subsequent primary thyroid cancer after another malignancy: latency trends in a population-based study.

PURPOSE: To evaluate the risk of a subsequent primary thyroid cancer (SPTC) in patients with common invasive cancers, with attention to latency trends and histology associations. METHODS: Patients with one of 10 common invasive cancers were followed from 1975 to 2008 in 9 registries participating in the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database. Standardized incidence ratios (SIRs) for SPTC were determined by the multiple primary-SIR program in SEER*Stat. RESULTS: A total of 2502 SPTCs were observed. Greatly elevated SIRs for SPTC were noted for 9 of 10 evaluated cancers in the 12 months after initial diagnosis. The SIRs remained elevated 12-59 months after diagnosis for all cancers except leukemia, uterine, and bladder cancers. Increased risks persisted 60-119 months beyond diagnosis for renal (SIR 2.56) and breast cancer (SIR 1.16); and 120+ months for renal cancer (SIR 2.46). Increased SPTC risk after renal and female breast cancers was mostly seen in nonirradiated patients. The principal histology association was between papillary thyroid cancer and renal cell carcinomas. CONCLUSIONS: Many common cancers are associated with increased risk of SPTC beyond 12 months of initial diagnosis. Although this can be explained partly by continued surveillance bias, radiation effects, and known rare familial associations for some tumors, these factors alone are unlikely to explain the persistent, significant two-way association with renal and breast cancers. Additional research is needed to further define the biological and environmental mechanisms underlying these associations.