To analyze the expression of AQP-5 in colorectal carcinoma, and to explore the relationship between AQP-5 expression and differentiation of the tumor.

48 cases of colorectal carcinoma samples were collected, including 17 cases of colon carcinoma and 31 cases of rectum carcinoma.Expression of AQP-5 was detected by immunohistochemical s-p method.

The positive expression rate of AQP-5 of carcinoma cells in colon carcinoma was 64.7%(11/17). In well-and moderately-differentiated carcinoma groups, the positive expression rate was 33.3%(3/9), however, that in poorly carcinoma was 100.0%(8/8), which showed difference between two groups(P<0.01). The positive expression rate of AQP-5 of carcinoma cells in rectum carcinoma was 70.9%(22/31). In well-and moderately-differentiated carcinoma groups, AQP-5 was expressed in 6 cases, with a positive rate of 46.2%, that in poorly carcinoma was 88.8%(16/18), there was statistically difference(P<0.05); AQP-5 expression was not different in two types of carcinoma(P>0.05).

AQP-5 seems to be a highly effective marker for differentiation in colon and rectum carcinoma, it may be very helpful to make the best choice of treatment and prognosis.