title: Novel murine model for colon cancer: non-operative trans-anal rectal injection.
abstract: 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.
authors.affiliation: Cancer Research Institute of M. D. Anderson Cancer Center Orlando, Orlando, Florida 32806, USA.
authors.forename: Melissa
authors.initials: M
authors.lastname: Donigan
authors.forename: Laurie S
authors.initials: LS
authors.lastname: Norcross
authors.forename: John
authors.initials: J
authors.lastname: Aversa
authors.forename: Jimmie
authors.initials: J
authors.lastname: Colon
authors.forename: Joshua
authors.initials: J
authors.lastname: Smith
authors.forename: Rafael
authors.initials: R
authors.lastname: Madero-Visbal
authors.forename: Shuan
authors.initials: S
authors.lastname: Li
authors.forename: Neal
authors.initials: N
authors.lastname: McCollum
authors.forename: Andrea
authors.initials: A
authors.lastname: Ferrara
authors.forename: Joseph T
authors.initials: JT
authors.lastname: Gallagher
authors.forename: Cheryl H
authors.initials: CH
authors.lastname: Baker
mesh_terms: 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*