Adenomatous polyposis coli-deficient zebrafish are susceptible to digestive tract neoplasia - PubMed (original) (raw)
Adenomatous polyposis coli-deficient zebrafish are susceptible to digestive tract neoplasia
Anna-Pavlina G Haramis et al. EMBO Rep. 2006 Apr.
Abstract
Truncation of the tumour suppressor adenomatous polyposis coli (APC) constitutively activates the Wnt/beta-catenin signalling pathway. This event constitutes the primary transforming event in sporadic colorectal cancer in humans. Moreover, humans or mice carrying germline truncating mutations in APC develop large numbers of intestinal adenomas. Here, we report that zebrafish that are heterozygous for a truncating APC mutation spontaneously develop intestinal, hepatic and pancreatic neoplasias that are highly proliferative, accumulate beta-catenin and express Wnt target genes. Treatment with the chemical carcinogen 7,12-dimethylbenz[a]anthracene accelerates the induction of these lesions. These observations establish apc-mutant zebrafish as a bona fide model for the study of digestive tract cancer.
Figures
Figure 1
Spontaneous intestinal adenomas in apc/+ fish. (A) Section of wild-type adult fish intestine stained for β-catenin. (B) Section of a large spontaneous polyp from a 15-month-old apc/+ fish stained for β-catenin. Note great disorganization of the intestinal architecture compared with the adjacent normal tissue (N). The inset depicts a high-magnification image of a region of the adenoma in which few cells have accumulated high levels of cytoplasmic and nuclear β-catenin (arrowheads). (C) Section of the intestine from a 20-month-old apc/+ fish stained for β-catenin. A large intestinal adenoma (A) is observed. The inset depicts a high–magnification image of the boxed area of the adenoma. Cells comprising the adenoma express high levels of β-catenin. (D) Immunocytochemistry with proliferating-cell nuclear antigen (PCNA) on adult fish intestine. Proliferation is restricted to the intervillus pockets between the villi (arrowheads). (E) Serial section of the polyp shown in (B) stained for PCNA. Most of the cells in the structure are PCNA+ and ectopic proliferative cells are found in the surface epithelium (arrowheads). (F) Serial section of the adenoma shown in (C) stained for PCNA. Note that almost all the epithelial cells in the neoplasia are proliferating. The inset depicts a higher magnification image of the boxed area of the adenoma in which ectopic proliferation is observed in the surface epithelium (arrowheads). Original magnification: (A,B,D,E) × 200; (C,F) × 20; inset in (B) × 400; inset in (C,F) × 200.
Figure 2
Spontaneous hepatic adenomas in _apc/_+ fish. (A) Section of a wild-type (wt) zebrafish liver stained for β-catenin. Bile ducts (bd), indicated by arrowheads, and vessels (v) are shown. β-catenin decorates the membranes of hepatocytes. (B) Section depicting a large spontaneous hepatic adenoma encompassing almost an entire liver lobe, from a 15-month-old apc/+ fish stained for β-catenin. Most of the cells in the lesion express high levels of β-catenin. The inset depicts a high-magnification image of some adenoma cells that have accumulated cytoplasmic and nuclear β-catenin (arrowheads). (C) Section of liver from a 14-month-old apc/+ fish stained with haematoxylin–eosin. Cells in this diseased liver appear clear and larger than normal hepatocytes, owing to increased glycogen accumulation (arrowhead). (D) Serial section of the wt liver shown in (A) stained for proliferating-cell nuclear antigen (PCNA). There is almost no proliferation in the adult zebrafish liver. (E) Serial section of the hepatic adenoma shown in (B) stained for PCNA. Most of the cells are proliferating. Note that there is a very good correlation between the PCNA+ cells and β-catenin-expressing cells. (F) In another region of the liver depicted in (C), apoptotic features such as fragmented nuclei (red arrowhead) and prominent nucleoli (black arrowhead) are observed in the lesion (demarcated with a striped line). Original magnification: (A,B,D,E) × 200; inset × 400; (C,F) × 400.
Figure 3
Upregulation of T-cell factor target genes in the adenomas of apc/+ fish. (A) Section of the intestine of a 20-month-old apc/+ fish containing a large intestinal adenoma (A) stained for cmyc. Cells in the adenoma express high levels of cmyc as compared with the normal intestinal tissue (N). The inset depicts a high-magnification image of a region of the adenoma in which most of the epithelial cells in crypt-like structures express high levels of cmyc (purple staining). (B) Serial section of the same intestinal adenoma stained for axin2. The inset depicts a high-magnification image of the boxed area of the adenoma. Epithelial cells in some crypt-like structures express high levels of axin2 (arrowheads). (C) Serial section of the intestinal adenoma stained for intestinal fatty acid-binding protein (ifabp). Note that in contrast to the normal intestinal tissue (N) that is positive for ifabp, the adenoma (demarcated by arrows) is negative for ifabp. (D) Diffuse hepatic neoplasia from a 14-month-old apc/+ fish stained for cmyc. Note that scattered cells in the adenoma are positive for cmyc, whereas those surrounding normal tissue (N) are negative. (E) Serial section of the same hepatic adenoma stained for axin2. Scattered cells in the neoplasia are positive for axin2. (F) Serial section of the same lesion stained for proliferating-cell nuclear antigen. Note scattered proliferative cells (brown staining). Original magnification: (A–C) × 20; (D,E) × 100; (F) × 200; insets in (A,B) × 200.
Figure 4
Intestinal and hepatic adenomas in 7,12-dimethylbenz[a]anthracene-treated apc/+ fish. (A) Section of the intestine of a 6-month-old 7,12-dimethylbenz[a]anthracene (DMBA)-treated apc/+ fish stained with β-catenin. A region with high levels of β-catenin compared with the adjacent normal tissue (N) is observed. The inset depicts a high-magnification image of the boxed area of the adenoma in which cells have accumulated high levels of cytoplasmic and nuclear β-catenin (arrowheads). (B) Serial section of the adenoma shown in (A) stained for proliferating-cell nuclear antigen (PCNA). Note that most of the cells in the structure are proliferating. The inset depicts a higher magnification image of the boxed area of the adenoma. Ectopic PCNA+ cells are found in the surface epithelium (arrowheads). (C) Section of liver and small intestine of a 6-month-old DMBA-treated apc/+ fish stained for β-catenin. A confined liver lesion demarcated by a striped line with high levels of β-catenin is depicted. The inset shows a high-magnification image of hepatocytes that have accumulated nuclear and cytoplasmic β-catenin. (D) Serial section of the lesion shown in (C) stained for PCNA. Cells in the lesion (demarcated by a striped line) are proliferating. The inset depicts a higher magnification image of PCNA+ cells. Original magnification: (A–D) × 100; insets × 200.
Figure 5
Pancreatic acinar cell adenomas in 7,12-dimethylbenz[a]anthracene-treated apc/+ fish. (A) Section depicting the pancreas of a wild-type zebrafish stained for β-catenin. Note weak diffuse staining in pancreatic acinar cells. d, duct; v, blood vessel. (B) Serial section of the same pancreas stained with proliferating-cell nuclear antigen (PCNA). There is almost no proliferation in the adult pancreas. (C) Section of a pancreatic neoplasia from a 7,12-dimethylbenz[a]anthracene-treated 14-month-old apc/+ fish stained for β-catenin. High levels of cytoplasmic and occasionally nuclear β-catenin are observed in the acinar cells. Note that secretory zymogenic granules seem to be diminished in the acinar cells. A small area of adjacent normal pancreas (N) is presented for comparison. f, fat cells. (D) Serial section of the same lesion stained for PCNA. Most of the cells are proliferating. Original magnification: (A–D) × 200.
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