First published online 27 June 2007
doi: 10.1242/dev.02875
Development 134, 2719-2725 (2007)
Published by The Company of Biologists 2007
Unique mechanisms of growth regulation and tumor suppression upon Apc inactivation in the pancreas
Alessandra Strom1,
Claire Bonal1,
Ruth Ashery-Padan2,
Naoko Hashimoto6,
M. Luisa Campos4,
Andreas Trumpp5,7,
Tetsuo Noda3,
Yoshiaki Kido6,
Francisco X. Real4,
Fabrizio Thorel1 and
Pedro L. Herrera1,*
1 Department of Genetic Medicine and Development, University of Geneva Faculty
of Medicine, 1 Rue Michel-Servet, CH-1211 Geneva 4, Switzerland.
2 Department of Human Molecular Genetics and Biochemistry, Sackler School of
Medicine, Tel-Aviv University, Israel.
3 Department of Cell Biology, Cancer Institute, Tokyo 135-8550, Japan.
4 Unitat de Recerca en Biologia Cel·lular i Molecular (URBCM), Institut
Municipal d'Investigació Mèdica (IMIM), Universitat Pompeu
Fabra, Dr Aiguader, 88 08003 Barcelona, Spain.
5 Genetics and Stem Cell Laboratory, Swiss Institute for Experimental Cancer
Research (ISREC), Ch. des Boveresses 155, CH-1066 Epalinges,
Switzerland.
6 Division of Diabetes, Digestive and Kidney Disease, Division of Diabetes
Metabolism and Endocrinology, Department of Clinical Molecular Medicine,
Department of Internal Medicine, Kobe University Graduate School of Medicine,
7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan.
7 Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Life
Sciences, CH-1015 Lausanne, Switzerland.
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Fig. 1. Postnatal pancreatomegaly after Apc loss. (A) An
E10.5 double-transgenic R26R;Pdx1-Cre+/- embryo stained
with X-gal (whole mount). ß-galactosidase activity is detected both in
the ventral and dorsal pancreatic buds. (B) Genomic PCR using DNA from
tail biopsies, isolated acini, ducts or islets of 2-month-old control (+/+ and
+/-) and ApcP-/- mice. Apc is efficiently
recombined in all pancreatic cell types in ApcP-/- adults
(300 bp band; unrecombined tissues yield a 1 kb-long PCR fragment). (C)
Freshly dissected pancreas of 2-month-old ApcloxP/loxP
(control) and ApcP-/- mice. (D)
Pancreas:body-weight ratio. The pancreatic mass is increased in
ApcP-/- mice (pancreatic weight: control,
0.39±0.108 g; ApcP-/-, 1.19±0.124 g). In
total, six mice were analyzed per group; ***P<0.001.
(E) Cell proliferation rate. The proliferation index was assayed with
anti-BrdU or anti-Ki67 antibody, as indicated. White bars, controls; black
bars, ApcP-/- mice (n=3 individuals per group;
**P<0.01; *P<0.05). vp/dp,
ventral/dorsal pancreatic primordia; s, stomach; d, duodenum; p, pancreas; sp,
spleen. Scale bar: 0.5 cm in C.
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Fig. 2. ß-catenin accumulates in
ApcP-/- acinar cells.
(A) Anti-pan ß-catenin immunofluorescence at E15.5, birth (P1), 1
month (confocal pictures are shown for this stage) and 12 months of age. In
control mice (left column), ß-catenin staining is found in cell membranes
at all stages analyzed. By contrast, in adult ApcP-/- mice
(right column) staining for ß-catenin is mainly nuclear in acinar cells
from P1 (open arrows) but remains peripheral in most islet and ductal cells,
as in controls. Notice that some islet cells display a cytoplasmic
ß-catenin staining (small arrow) in old ApcP-/- mice.
(B) Western blot of total protein extracts from E15.5 and adult
pancreata (50 µg per lane) using anti-unphosphorylated ß-catenin
antibody and anti-ß-catenin-(phospho Y142) antibody. Unphosphorylated
ß-catenin accumulates only in pancreatic extracts from
ApcP-/- adult mice and is always undetectable in isolated
islets (right). ß-catenin-(phospho Y142) is abundant in adult acini, but
undetectable in developing primordia or in isolated islets (1-month-old),
whether control or ApcP-/-. ß-tubulin and actin
(lower row) show equal loading. d, duct; i, islet. Scale bars: 20 µm.
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Fig. 3. Pancreatomegaly is c-myc dependent. (A) Freshly
dissected pancreata from 2-month-old ApcP-/- and
ApcP-/-;c-mycP-/- mice. Pancreatomegaly does
not appear in the absence of the two c-myc alleles. (B)
Anti-ß-catenin immunofluorescence on 2-month-old
ApcP-/- and
ApcP-/-;c-mycP-/- pancreatic sections. Notice
the nuclear localization of ß-catenin in acinar cells of mice of both
genotypes (open arrows). Islets are depicted with a dashed line. Paraffin
sections were 5 µm thick. Small arrows show cytoplasmic ß-catenin in
islets and ducts (d). (C) Western blot of total protein extracts from
adult pancreas (50 µg per lane) using anti-unphosphorylated ß-catenin
antibody. Unphosphorylated ß-catenin accumulates in the pancreas of
ApcP-/-;c-mycP-/- mice, as in
ApcP-/- animals. ß-tubulin shows equal loading.
(D) ß-cell area in
ApcP-/-;c-mycP-/- mice is similar to that of
controls, whereas it is lower in ApcP-/- animals. A total
of three mice were analyzed per group; *P<0.01. d,
duodenum (A), duct (B); p, pancreas; sp, spleen. Scale bar: 0.5 cm in A; 20
µm in B.
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© The Company of Biologists Ltd 2007
