An Msh2 conditional knockout mouse for studying intestinal cancer and testing anticancer agents.
OBJECTIVE
Mutations in the DNA mismatch repair (MMR) gene MSH2 cause Lynch syndromes I and II and sporadic colorectal cancers. Msh2(null) mice predominantly develop lymphoma and do not accurately recapitulate the colorectal cancer phenotype.


METHODS
We generated and examined mice with a conditional Msh2 disruption (Msh2(LoxP)), permitting tissue-specific gene inactivation. ECMsh2(LoxP/LoxP) mice carried an EIIa-Cre transgene, and VCMsh2(LoxP/LoxP) mice carried a Villin-Cre transgene. We combined the VCMsh2(LoxP) allele with either Msh2(Delta7null) (VCMsh2(LoxP/null)) or Msh2(G674D) mutations (VCMsh2(LoxP/G674D)) to create allelic phase mutants. These mice were given cisplatin or 5-fluorouracil/leucovorin and oxaliplatin (FOLFOX), and their tumors were measured by magnetic resonance imaging.


RESULTS
Embryonic fibroblasts from ECMsh2(LoxP/LoxP) mice do not express MSH2 and are MMR deficient. Reverse transcription, polymerase chain reaction, and immunohistochemistry from VCMsh2(LoxP/LoxP) mice demonstrated specific loss of Msh2 messenger RNA and protein from epithelial cells of the intestinal tract. Microsatellite instability was observed in all VCMsh2 strains and limited to the intestinal mucosa. Resulting adenomas and adenocarcinomas had somatic truncation mutations to the adenomatous polyposis coli (Apc) gene. VCMsh2(LoxP/LoxP) mice did not develop lymphoma. Comparison of allelic phase tumors revealed significant differences in multiplicity and size. When treated with cisplatin or FOLFOX, tumor size was reduced in VCMsh2(LoxP/G674D) but not VCMsh2(LoxP/null) tumors. The apoptotic response to FOLFOX was partially sustained in the intestinal mucosa of VCMsh2(LoxP/G674D) animals.


CONCLUSIONS
Msh2(LoxP/LoxP) mice in combination with appropriate Cre recombinase transgenes have excellent potential for preclinical modeling of Lynch syndrome, MMR-deficient tumors of other tissue types, and use in drug development.
Kucherlapati
Melanie H
MH
Department of Medicine/Division of Genetics, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA. mkucherlapati@partners.org
Lee
Kyeryoung
K
Nguyen
Andrew A
AA
Clark
Alan B
AB
Hou
Harry
H
Rosulek
Andrew
A
Li
Hua
H
Yang
Kan
K
Fan
Kunhua
K
Lipkin
Martin
M
Bronson
Roderick T
RT
Jelicks
Linda
L
Kunkel
Thomas A
TA
Kucherlapati
Raju
R
Edelmann
Winfried
W
D000230:Adenocarcinoma / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D000236:Adenoma / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology*; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D004195:Disease Models, Animal; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D005472:Fluorouracil / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D017491:Genes, APC; D005838:Genotype; D007150:Immunohistochemistry; D019426:Integrases / Q000235:genetics; D007414:Intestinal Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002955:Leucovorin / Q000494:pharmacology; D008279:Magnetic Resonance Imaging; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008840:Microfilament Proteins / Q000235:genetics; D053842:Microsatellite Instability; D051718:MutS Homolog 2 Protein / Q000172:deficiency* / Q000235:genetics; D009154:Mutation; D009944:Organoplatinum Compounds / Q000494:pharmacology; D010641:Phenotype; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D047368:Tumor Burden / Q000187:drug effects
D000970:Antineoplastic Agents; D008840:Microfilament Proteins; D009944:Organoplatinum Compounds; C026615:villin; C045073:Cre recombinase; D019426:Integrases; C497173:Msh2 protein, mouse; D051718:MutS Homolog 2 Protein; D002945:Cisplatin; D002955:Leucovorin; D005472:Fluorouracil