Zebrafish reporter lines reveal in vivo signaling pathway activities involved in pancreatic cancer

Disease Models & Mechanisms. 2014;7(7):883-894 DOI 10.1242/dmm.014969

 

Journal Homepage

Journal Title: Disease Models & Mechanisms

ISSN: 1754-8403 (Print); 1754-8411 (Online)

Publisher: The Company of Biologists

LCC Subject Category: Medicine: Pathology

Country of publisher: United Kingdom

Language of fulltext: English

Full-text formats available: PDF

 

AUTHORS

Marco Schiavone
Elena Rampazzo
Alessandro Casari
Giusy Battilana
Luca Persano
Enrico Moro
Shu Liu
Steve D. Leach
Natascia Tiso
Francesco Argenton

EDITORIAL INFORMATION

Blind peer review

Editorial Board

Instructions for authors

Time From Submission to Publication: 21 weeks

 

Abstract | Full Text

Pancreatic adenocarcinoma, one of the worst malignancies of the exocrine pancreas, is a solid tumor with increasing incidence and mortality in industrialized countries. This condition is usually driven by oncogenic KRAS point mutations and evolves into a highly aggressive metastatic carcinoma due to secondary gene mutations and unbalanced expression of genes involved in the specific signaling pathways. To examine in vivo the effects of KRASG12D during pancreatic cancer progression and time correlation with cancer signaling pathway activities, we have generated a zebrafish model of pancreatic adenocarcinoma in which eGFP-KRASG12D expression was specifically driven to the pancreatic tissue by using the GAL4/UAS conditional expression system. Outcrossing the inducible oncogenic KRASG12D line with transgenic zebrafish reporters, harboring specific signaling responsive elements of transcriptional effectors, we were able to follow TGFβ, Notch, Bmp and Shh activities during tumor development. Zebrafish transgenic lines expressing eGFP-KRASG12D showed normal exocrine pancreas development until 3 weeks post fertilization (wpf). From 4 to 24 wpf we observed several degrees of acinar lesions, characterized by an increase in mesenchymal cells and mixed acinar/ductal features, followed by progressive bowel and liver infiltrations and, finally, highly aggressive carcinoma. Moreover, live imaging analysis of the exocrine pancreatic tissue revealed an increasing number of KRAS-positive cells and progressive activation of TGFβ and Notch pathways. Increase in TGFβ, following KRASG12D activation, was confirmed in a concomitant model of medulloblastoma (MDB). Notch and Shh signaling activities during tumor onset were different between MDB and pancreatic adenocarcinoma, indicating a tissue-specific regulation of cell signaling pathways. Moreover, our results show that a living model of pancreatic adenocarcinoma joined with cell signaling reporters is a suitable tool for describing in vivo the signaling cascades and molecular mechanisms involved in tumor development and a potential platform to screen for novel oncostatic drugs.