散发性大肠癌组织及粪便P53蛋白、K-ras及APC基因的检测

Detection of P53 protein, K-ras and APC gene mutation in sporadic colorectal cancer tissue and exfoliative epithelial cells in stool

AIM To investigate the mutation of P 53, K-ras and APC gene in human stools and its significance in diagnosis of colorectal cancer. METHODS Tumor tissue and colorectal exfoliative cells in stools were collected from 27 patients and then, using S-P method, P 53 protein was detected. The mutation of K- ras code 12, 13 and APC gene at exon 15 MCR in 22 specimens of tumor mucosa, 9 specimens of normal mucosa and 10 samples of stool were determined by polymerase chain reaction amplification and restriction enzyme analysis (PCR-RFLP) and polymerase chain reaction and its single strand conformation polymorphism (PCR-SSCP) respectively. RESULTS In ten (37%) of 27 cases of colorectal cancer, P 53 was positive in the exfoliative cells. The agreement rate of P 53 expression in tumor and exfoliative cells was 85% (23/27). In sixteen (73%) of 22 samples of tumor tissue and 5 (50%) of 10 samples of stool (511%), the mutations of K-ras code 12 were positive. The agreement rate of K-ras code 12 mutations in tumor and stool was 90% (9/10). No K-ras code 13 mutations were observed in stool and tumor mucosa. The mutations were detected in nine (41%) of 22 specimens of tumor mucosa and 4 (40%) of 10 samples of stool. The agreement rate in tumor and stool was 90% (9/10). Detection of P 53, K-ras and APC gene mutation at same time, the sensitivity for colorectal cancer in tissues vs stool was 100% vs 90%. CONCLUSION The mutation of P 53, K-ras code 12 and APC frequently occurs on colorectal carcinoma, detection of P 53, K-ras and APC gene mutation could raise the positive rate for colorectal cancer. Investigation of gene mutation in the stool reflects the real situation of that in the tissue, its detection may be a useful noninvasive molecular approach for screening and diagnosis of colorectal carcinoma.