Prognostic significance of Bcl-2, Bcl-x(L/S), Bax and Bak expressions in colorectal carcinomas

The immunohistochemical expressions of the apoptosis-related proteins Bcl-2 , Bcl-x(L/S), Bar and Bak were investigated in tumor specimens selected fro m 58 consecutive patients undergoing surgery for advanced colorectal carcin oma. The expression patterns in 50 specimens of adjacent normal colonic muc osa were also examined. In the normal colonic mucosa, Bcl-2-positive epithe lial cells tended to be located at the base of the crypts, while the Bcl-x( L/S)-, Bax- and Bak-positive epithelial cells tended to be located at the l uminal surface. The intracellular expression patterns of Bcl-2 and Bar were diffuse cytoplasmic, whereas those of Bcl-x(L/S) and Bak were granular cyt oplasmic. In the adenocarcinomas, the intracellular expression patterns of all antibodies were diffuse cytoplasmic, and the percentages of Bcl-2-, Bcl -x(L/S)-, Bax- and Bak-positive cases (>20% of cancer cells labeled) were 2 9%, 43%, 45% and 69%, respectively. Bar expression was significantly correl ated with less lymph vessel invasion (p=0.02) and less depth of invasion (p =0.04). In relation to prognosis (5-year-survival), the patients with Bar-p ositive tumors had significantly better prognoses than the patients who had Bar-negative tumors (p<0.05). However, the Bcl-2, Bcl-x(L/S) and Bak expre ssions were not related to any clinicopathological factors. examined. Thus, Bar expression may be an additional prognostic marker in colorectal carcin omas.