Development of a mouse model for sporadic and metastatic colon tumors and its use in assessing drug treatment.
Most genetically engineered mouse (GEM) models for colon cancer are based on tissuewide or germline gene modification, resulting in tumors predominantly of the small intestine. Several of these models involve modification of the adenomatous polyposis coli (Apc) gene and are excellent models for familial cancer predisposition syndromes. We have developed a stochastic somatic mutation model for sporadic colon cancer that presents with isolated primary tumors in the distal colon and recapitulates the entire adenoma-carcinoma-metastasis axis seen in human colon cancer. Using this model, we have analyzed tumors that are either solely mutant in the Apc gene or in combination with another colon cancer-associated mutant gene, the Kras G12D allele. Because of the restricted location in the distal colon, the natural history of the tumors can be analyzed by serial colonoscopy. As the mammalian target of rapamycin (mTOR) pathway is a critical component of the complex signaling network in colon cancer, we used this model to assess the efficacy of mTOR blockade through rapamycin treatment of mice with established tumors. After treatment, Apc mutant tumors were more than 80% smaller than control tumors. However, tumors that possessed both Apc and Kras mutations did not respond to rapamycin treatment. These studies suggest that mTOR inhibitors should be further explored as potential colorectal cancer therapies in patients whose tumors do not have activating mutations in KRAS.
Hung
Kenneth E
KE
Division of Gastroenterology, Tufts Medical Center, Boston, MA 02111, USA. khung@tuftsmedicalcenter.org
Maricevich
Marco A
MA
Richard
Larissa Georgeon
LG
Chen
Wei Y
WY
Richardson
Michael P
MP
Kunin
Alexandra
A
Bronson
Roderick T
RT
Mahmood
Umar
U
Kucherlapati
Raju
R
D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000627:therapeutic use*; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D004195:Disease Models, Animal; D018450:Disease Progression; D017491:Genes, APC; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation; D009362:Neoplasm Metastasis; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D020123:Sirolimus / Q000627:therapeutic use*; D058570:TOR Serine-Threonine Kinases
D000903:Antibiotics, Antineoplastic; D047908:Intracellular Signaling Peptides and Proteins; C546842:MTOR protein, human; C546843:mTOR protein, mouse; D017346:Protein Serine-Threonine Kinases; D058570:TOR Serine-Threonine Kinases; C495971:Hras protein, mouse; D016283:Proto-Oncogene Proteins p21(ras); D020123:Sirolimus