Novel murine model for colon cancer: non-operative trans-anal rectal injection.
BACKGROUND
This study was conducted to develop a modified murine model of colon cancer that is non-operative. Currently, the most accurate orthotopic murine model of colon cancer requires an invasive procedure involving cecal injection of colon cancer cells and therefore limits the ability to perform immunological studies subsequent to cecal resections.


METHODS
Murine colon cancer (CT26) cells were injected submucosally into the distal, posterior rectum of BALB/c mice. Care was taken not to pass transmurally into the pelvic cavity. Different magnifications (10x versus 100x) were used for injection, and primary tumor growth and metastatic disease were studied.


RESULTS
In the initial study, 3/7 mice injected using 10x magnifications had notable, large tumor originating from the rectal wall, and histology revealed that all excised tumors were poorly differentiated adenocarcinoma. In the second study, 8/10 mice injected using 100x magnifications had notable tumor originating from the rectal well, and 4/8 mice had abnormal lung tissue with pathological evidence of hemorrhagic pulmonary edema. The use of 10x magnification resulted in 43% tumor take. In sharp contrast, 80% tumor take was observed with 100x magnification. The overall success of tumor take was 65% using the trans-anal rectal injection model.


CONCLUSIONS
Our modified orthotopic murine model of colon cancer offers an alternative non-operative murine model for colon cancer and is less invasive than the traditional orthotopic model (i.e., cecal injection). This model may allow for more accurate investigations of inflammation and immune responses to surgical intervention without the influence of previous abdominal surgery.
Donigan
Melissa
M
Cancer Research Institute of M. D. Anderson Cancer Center Orlando, Orlando, Florida 32806, USA.
Norcross
Laurie S
LS
Aversa
John
J
Colon
Jimmie
J
Smith
Joshua
J
Madero-Visbal
Rafael
R
Li
Shuan
S
McCollum
Neal
N
Ferrara
Andrea
A
Gallagher
Joseph T
JT
Baker
Cheryl H
CH
D000230:Adenocarcinoma / Q000556:secondary*; D001003:Anal Canal; D000818:Animals; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000473:pathology*; D004195:Disease Models, Animal; D007267:Injections / Q000379:methods; D008168:Lung / Q000473:pathology; D008175:Lung Neoplasms / Q000556:secondary; D051379:Mice; D008807:Mice, Inbred BALB C; D009368:Neoplasm Transplantation / Q000379:methods*; D012004:Rectal Neoplasms / Q000473:pathology; D012007:Rectum / Q000473:pathology*