Objective To investigate cyclooxygenase-2 (COX-2) expression and its relationship with mismatch repair (MMR) protein expression and microsatellite instability (MSI) in hereditary nonpolyposis colorectal cancer (HNPCC). Methods A total of 28 cases of colorectal adenoma and 14 cases of colorectal carcinoma were collected between July 2003 and July 2007 from 33 HNPCC families. Sporadic colorectal adenoma (n=32) and carcinoma patients (n=24) served as controls. With samples of tumor tissues and normal colonic mucosa collected from the patients, the protein expressions of COX-2 and MMR (hMLH1, hMSH2, and hMSH6) were examined with immunohistochemical assay. Frequency of MSI in five standard MSI loci BAT25, BAT26, D2S123, D5S346, and D17S250 were analyzed by means of polymerase chain reaction. Results The rate of COX-2 high-expression was 53.6% (15/28) and 42.9% (6/14) in HNPCC adenoma and carcinoma; 62.5% (20/32) and 91.7% (22/24) in sporadic adenoma and carcinoma, respectively. That rate was lower in HNPCC carcinoma than in sporadic carcinoma (P<0.05). MMR-deletion rate and percentage of high-frequency MSI (MSI-H) in HNPCC carcinoma were higher than those in sporadic colorectal carcinoma [both 71.4% (10/14) vs. 12.5% (3/24), both P<0.01]. Among the 10 MMR-deficient HNPCC carcinoma patients, COX-2 low-expression was observed in 8 cases (80.0%), while COX-2 high-expression was observed in all of the 4 MMR-positive HNPCC carcinoma cases (P<0.05). In comparison to MMR positive HNPCC carcinoma, HNPCC adenoma, and sporadic carcinoma, COX-2 expression was significantly lower in corresponding MMR-deficient cases (all P<0.05). The rates of COX-2 low-expression in HNPCC adenoma, HNPCC carcinoma, and sporadic carcinoma with MSI-H were significantly higher than those in the cases with microsatellite stability (all P<0.05). Conclusion COX-2 is expressed at a low level in HNPCC carcinoma, different from the high COX-2 expression in sporadic carcinoma.
Peng Jin Jian-qiu Sheng Ying-hui Zhang Ai-qin Li Zi-tao Wu Shi-rong Li
Objective To explore the clinicopathological features of non-familial colorectal cancer with high-frequency microsatellite instability (MSI-H). Methods One hundred and fifty patients with colorectal cancer who had no family history were enrolled in this study from June 2006 to June 2008. Five standard microsatellite loci including BAT25, BAT26, D2S123, D5S346, and D17S250 were amplified with immunofluorescent polymerase chain reaction. The patient information including age, sex, and tumor location was recorded. Pathological features including differentiation, mucinous differentiation, histological heterogeneity, and Crohn's-like reaction were observed under light microscope. The presence of tumor-infiltrating lymphocytes (TLs, CD4+ and CD8+) was detected by means of immunohistochemistry. A regression equation was obtained by stepwise logistic regression analysis to evaluate the relationship between MSI-H phenotype in colorectal cancer ands pathological features. Results MSI-H phenotype occurred in 13.33% of the 150 patients with non-familial colorectal cancer. Poor differentiation, histological heterogeneity, Crohn's-like reaction, and presence of TLs were found to be independent factors to identify MSI-H non-familial colorectal cancer. Logistic regression equation showed an overall sensitivity of 70.0%, specificity of 99.2%, and accuracy of 95.3% in identifying MSI-H non-familial colorectal cancer. Conclusion MSI-H non-familial colorectal cancer manifests specific pathological features, which may be relied upon for effective identification of that disease.
Peng Jin Xiao-ming Meng Jian-qiu Sheng Zi-tao Wu Lei Fu He-juan An Ying Han Shi-rong Li
