Techniques for Modeling Human Intestinal Cancer in Mice

October 22-26, 2000

Presented by

The Jackson Laboratory

Faculty: Catherine Booth, William F. Dove, Jeffrey I. Gordon, Richard B.
Halberg, Julie Ann O\'Shea, Thaddeus S. Stappenbeck, and Robert H.
Whitehead

Edited by: W. F. Dove, R. B. Halberg, L. Clipson,

and I. L. Riegel

The McArdle Laboratory for Cancer Research

University of Wisconsin-Madison

Send any corrections or additions to dove@oncology.wisc.edu

**11. Background - Cancer Genetics**

**WF Dove and RB Halberg**

**McArdle Laboratory, University of Wisconsin**

Balmain A, Nagase H. Cancer resistance genes in mice: models for the
study of tumour modifiers. Trends Genet 1998 Apr;14(4):139-44

Onyx Pharmaceuticals, Richmond, CA 94806, USA. allan@onyx-pharm.com

Smokers have frequently been heard to defend their habit by recounting
anecdotes about relatives or friends who have smoked heavily for many
years without developing cancer. While individuals who have survived
many years of repeated mutagen exposure are probably very rare, their
existence suggests that some people are intrinsically resistant to the
effects of carcinogens, probably because of their genetic background.
This interpretation is supported by studies on mouse strains that are
highly resistant to the development of tumors induced by treatment with
exogenous carcinogens. In this review we discuss the advantages of the
mouse as a model system for the isolation of cancer-resistance genes
that have potentially important uses in diagnostics, prevention and
tumor therapy.

Publication Types:

Review

Review, tutorial

PMID: 9594661

Nadeau JH, Frankel WN. The roads from phenotypic variation to gene
discovery: mutagenesis versus QTLs. Nat Genet 2000 Aug;25(4):381-4

Department of Genetics, Case Western Reserve University School of
Medicine and Center for Human Genetics, University Hospitals of
Cleveland, Cleveland, USA. jhn4@po.cwru.edu

In model organisms, chemical mutagenesis provides a powerful alternative
to

natural, polygenic variation \[for example, quantitative trait loci
(QTLs)\] for identifying functional pathways and complex disease genes.
Despite recent

progress in QTLs, we expect that mutagenesis is will ultimately prove
more effective because the prospects of gene identification are high and
every gene affecting a trait is potentially a target.

PMID: 10932178

Dietrich WF, Lander ES, Smith JS, Moser AR, Gould KA, Luongo C,
Borenstein N, Dove W. Genetic identification of Mom-1, a major modifier
locus affecting Min-induced intestinal neoplasia in the mouse. Cell 1993
Nov 19;75(4):631-9

Whitehead Institute for Biomedical Research, Massachusetts Institute of

Technology, Cambridge 02142.

Mutations in the human APC gene caused various familial colon cancer
syndromes. The Multiple intestinal neoplasia (Min) mouse provides an
excellent model for familial colon cancer: it carries a mutant mouse Apc
gene and develops many intestinal adenomas. Here, we analyze how this
tumor phenotype is dramatically modified by genetic background. We
report the genetic mapping of a locus that strongly modifies tumor
number in Min/+ animals. This gene, Mom-1 (Modifier of Min-1), maps to
distal chromosome 4 and controls about 50% of genetic variation in tumor
number in two intraspecific backcrosses. The mapping is supported by a
LOD score exceeding 14. Interestingly, Mom-1 lies in a region of synteny
conservation with human chromosome 1p35-36, a region of frequent somatic
loss of heterozygosity in a variety of human tumors, including colon
tumors. These results provide evidence of a major modifier affecting
expression of an inherited cancer syndrome.

PMID: 8242739

Gould KA, Dietrich WF, Borenstein N, Lander ES, Dove WF. Mom1 is a
semi-dominant modifier of intestinal adenoma size and multiplicity in
Min/+ mice. Genetics 1996 Dec;144(4):1769-76

McArdle Laboratory for Cancer Research, University of Wisconsin, Madison
53706, USA.

The intestinal tumor multiplicity in mice heterozygous for ApcMin is
strongly modulated by genetic background. On the sensitive C57BL/6J (B6)
background, mice develop large numbers of intestinal adenomas. The AKR/J
(AKR) strain carries alleles that correlate with a strong reduction in
tumor multiplicity. To study

the effect of one of these modifiers, Mom1, we have generated a mouse
line in which the AKR allele of Mom1 is carried on the sensitive B6
genetic background. This strain was produced by using a marker-assisted
selection method to eliminate unlinked AKR alleles more rapidly. The
application and efficiency of this method are discussed. We used this
strain to determine that Mom1 affects both tumor multiplicity and tumor
size in a semi-dominant fashion.

PMID: 8978062

Cormier RT, Hong KH, Halberg RB, Hawkins TL, Richardson P, Mulherkar R,
Dove WF, Lander ES. Secretory phospholipase Pla2g2a confers resistance
to intestinal tumorigenesis. Nat Genet 1997 Sep;17(1):88-91. Comment in:
Nat Genet. 1997 Sep;17(1):7-8

McArdle Laboratory for Cancer Research, University of Wisconsin, Madison
53706, USA.

Individuals inheriting the same mutation predisposing to cancer may show
very different outcomes, ranging from early aggressive cancer to
disease-free survival. Experimental mouse models can provide a powerful
tool to identify factors in the environment and genetic background that
account for such modifications. The Min mouse strain, in which the
ApcMin mutation disrupts the mouse homologue of the human familial
polyposis gene, develops intestinal neoplasms whose multiplicity is
strongly affected by genetic background. We previously mapped a strong
modifier locus, Mom1 (modifier of Min-1), to a 4-cM region on mouse
chromosome 4 containing a candidate gene Pla2g2a encoding a secretory
phospholipase. Here, we report that a cosmid transgene

overexpressing Pla2g2a caused a reduction in tumour multiplicity and
size, comparable to that conferred by a single copy of the resistance
allele of Mom1. These results offer strong evidence that this secretory
phospholipase can provide active tumour resistance. The association of
Pla2g2a with Mom1 thus withstands a strong functional test and is likely
to represent the successful identification of a

polymorphic quantitative trait locus in mammals.

PMID: 9288104

Cormier RT, Bilger A, Lillich AJ, Halberg RB, Hong KH, Gould KA,
Borenstein N,

Lander ES, Dove WF. The Mom1AKR intestinal tumor resistance region
consists of Pla2g2a and a locus distal to D4Mit64. Oncogene 2000 Jun
29;19(28):3182-92

McArdle Laboratory for Cancer Research, University of Wisconsin, Madison
53706, USA.

The Mom1 (Modifier of Min-1) region of distal chromosome 4 was
identified during a screen for polymorphic modifiers of intestinal
tumorigenesis in ApcMin/+ mice. Here, we demonstrate that the Mom1AKR
allele consists of two genetic components. These include the secretory
phospholipase Pla2g2a, whose candidacy as a Mom1 resistance modifier has
now been tested with several transgenic lines. A second region, distal
to Pla2g2a, has also been identified using fine structure recombinants.
Pla2g2aAKR transgenic mice demonstrate a modest resistance to
tumorigenesis in the small intestine and a very robust resistance in the
large intestine. Moreover, the tumor resistance in the colon of
Pla2g2aAKR animals is dosage-dependent, a finding that is consistent
with our observation that Pla2g2a is expressed in goblet cells. By
contrast, mice carrying the distal Mom1 modifier demonstrate a modest
tumor resistance that is confined to the small intestine. Thus, the
phenotypes of these two modifier loci are complementary, both in their
quantitative and regional effects. The additive effects and tight
linkage of these modifiers may have been necessary for the initial
identification of the Mom1 region.

PMID: 10918573

Gould KA, Dove WF. Analysis of the Mom1 modifier of intestinal neoplasia
in mice. Exp Lung Res 1998 Jul-Aug;24(4):437-53

McArdle Laboratory for Cancer Research and Laboratory of Genetics,
University of Wisconsin, Madison, USA.

Although the methodology for mapping genes controlling susceptibility to
tumor development in mice is becoming well established, it remains a
formidable challenge to move from linkage to locus. Positional cloning,
now commonly used in the identification of loci affecting a qualitative
phenotype, has yet to be successfully applied to quantitative trait
loci. This study describes the application of candidate gene testing, a
method complementary to positional cloning. The method has been applied
to evaluate candidates for the quantitative trait locus, Mom1, which
modifies the susceptibility of ApcMin/+ mice to spontaneous intestinal
tumor development. The authors also discuss the further testing of one
candidate, the phospholipase gene Pla2g2a, by transgenesis. Finally,
studies on the mode of action of Mom1 are discussed in light of the
evidence that Mom1 encodes this secretory phospholipase.

Publication Types:

Review

Review, tutorial

PMID: 9659576

Gould KA, Dove WF. Action of Min and Mom1 on neoplasia in ectopic
intestinal grafts. Cell Growth Differ 1996 Oct;7(10):1361-8

McArdle Laboratory for Cancer Research and Laboratory of Genetics,
University of Wisconsin, Madison, 53706, USA.

Mice heterozygous for Min, a mutant allele of Apc, develop adenomas
throughout the intestinal tract. Tumor multiplicity in Min mice is
influenced by genetic modifier loci. Previously, we mapped one of these
modifier loci, Mom1, to distal mouse chromosome 4. Mom1 is a
semidominant modifier of both tumor size and multiplicity in Min mice.
Recent evidence suggests that Mom1 may encode a secretory phospholipase,
Pla2g2a. Pla2g2a is expressed in a variety of cell types and seems to be
involved in inflammatory responses and bacterial defense mechanisms.
Here, we determine whether Min and Mom1 act in a tissue-autonomous
fashion using ectopic intestinal isografts. Within the small intestinal
grafts, both Min and Mom1 act in a tissue-autonomous manner. There is no
evidence that either Min or Mom1 has a systemic effect on tumor
development. However, within the colonic grafts, the Min phenotype does
not appear to be autonomous; the development of colonic tumors in Min
mice seems dependent on factors beyond the Min genotype of the colonic
epithelium. Micro-environmental factors, such as digestive secretions,
dietary components, or intestinal flora, may be critical factors
contributing to the development of Min-induced colonic tumors. However,
these factors are not required for the action of Min or Mom1 within the
small intestine.

PMID: 8891340

Gould KA, Dove WF. Localized gene action controlling intestinal
neoplasia in mice. Proc Natl Acad Sci U S A 1997 May 27;94(11):5848-53

McArdle Laboratory for Cancer Research and Laboratory of Genetics,
University of Wisconsin, Madison, WI 53706, USA.

Mice heterozygous for the ApcMin (Min) mutation develop adenomas
throughout the intestinal tract. Apc is believed to be involved in cell
migration, adhesion, and polarity. Adenoma multiplicity and growth rate
are modulated by an unlinked modifier locus, Mom1. The secretory
phospholipase Pla2g2a is a candidate for Mom1. Here, we investigate the
range of action of Apc and Mom1. Analysis of chimeric Min mice indicates
that the actions of both Apc and Mom1 are localized within the cell
lineage that gives rise to intestinal tumors.

PMID: 9159163

Cormier RT, Dove WF. Dnmt1N/+ reduces the net growth rate and
multiplicity of intestinal adenomas in C57BL/6-multiple intestinal
neoplasia (Min)/+ mice independently of p53 but demonstrates strong
synergy with the modifier of Min 1(AKR) resistance allele. Cancer Res
2000 Jul 15;60(14):3965-70

McArdle Laboratory for Cancer Research, University of Wisconsin, Madison
53706, USA.

Altered patterns of the 5-cytosine methylation of genomic DNA are
associated with the development of a wide range of human cancers. We
have studied the mechanisms and genetic pathways by which a targeted
heterozygous deficiency in the murine 5-cytosine DNA methyltransferase
gene (Dnmt1(N/+)) diminishes intestinal tumorigenesis in
C57BL/6-multiple intestinal neoplasia (Min)/+ mice. We found that
Dnmt1(N/+) retards the net growth rate of intestinal adenomas and
reduces tumor multiplicity by approximately 50%. This tumor resistance
affects the entire intestinal tract and is independent of the status of
modifier of Min 1 and p53, two loci that have been found to confer
strong resistance to Min-induced neoplasia Interestingly, Dnmt/(N/+) and
modifier of Min 1 resistance interact synergistically, together
virtually eliminating tumor incidence. This finding may provide an
insight into potential combinatorial therapeutic approaches for treating
human colon cancer.

PMID: 10919675