Transforming growth factor-alpha (TGF-alpha) is not needed for malignant transformation in experimental colitis.
BACKGROUND
Transforming growth factor-alpha (TGF-alpha) is a key mediator of colonic mucosal protection and/or repair mechanisms in orally induced acute dextran sodium sulphate (DSS) colitis. However, it also has been suggested that TGF-alpha may contribute to malignant transformation in the colon. The aim of the studies was to determine whether TGF-alpha is needed for malignant transformation in orally induced chronic DSS colitis using TGF-alpha deficient mice (wa-1) and Balb/c mice, a strain competent in TGF-alpha.


METHODS
Chronic colitis was induced by oral administration of DSS (5%) for 7 days followed by drinking water for 10 days in wa-1 and Balb/c mice (n = 20, per group). In the two subsequent cycles (7 days DSS, 10 days water) 3% DSS-water was utilized due to a high mortality in the wa-1 group. Mucosal injury severity was assessed histologically and graded (three grades). A crypt damage score (CDS) reflecting all three grades of mucosal pathology was calculated. Mucosal dysplasia and cancerous lesions were noted.


RESULTS
Seven per cent of the entire colonic mucosa was completely destroyed in wa-1 animals compared to 3% in Balb/c mice (P < 0.05). The CDS was 10.2 +/- 0.4 and 4.8 +/- 0.3 in wa-1 and Balb/c mice, respectively (P < 0.05). Fifteen incidences of mucosal dysplasia were found in the 10 surviving wa-1 animals and 31 incidences were found in 20 Balb/c animals. In both groups, one fully developed adenomatous cancerous lesion was present.


CONCLUSIONS
The markedly increased severity of mucosal injury in chronic induced DSS colitis in TGF-alpha deficient wa-1 mice compared to Balb/c mice further substantiates that endogenous TGF-alpha is a pivotal mediator of protection and/or healing mechanisms in the colon. The appearance of dysplastic and cancerous lesions in TGF-alpha deficient animals suggests that TGF-alpha per se is not essential for malignant mucosal cell transformation in colitis.
Egger
B
B
Dept. of Visceral and Transplantation Surgery, University of Bern, Switzerland.
Chai
N N
NN
Wang
L
L
French
S W
SW
Büchler
M W
MW
Eysselein
V E
VE
D000818:Animals; D002471:Cell Transformation, Neoplastic / Q000473:pathology*; D002908:Chronic Disease; D003092:Colitis / Q000473:pathology*; D016264:Dextran Sulfate; D004195:Disease Models, Animal; D005260:Female; D007413:Intestinal Mucosa / Q000473:pathology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008815:Mice, Inbred Strains; D011336:Probability; D011863:Radioimmunoassay; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric; D016211:Transforming Growth Factor alpha / Q000032:analysis*
D016211:Transforming Growth Factor alpha; D016264:Dextran Sulfate