A Study On The Comparative Analysis Of The Mutation Of P53and K-ras Gene Of Colorectal Cancers

ObjectiveThe aim of this study is not only to investigate the incidence of P53and K-ras gene mutation in normal mucosa tissue, colorectal adenomas,primary colorectal cancers and multiple primary colorectal carcinomas, butto identify that is there any relationship between the incidence of P53andK-ras gene mutation and the Clinicopathologic features of colorectaladenomas and primary colorectal cancers.Methods1．25normalsamples,38samples ofcolorectaladenoma,78samples ofprimary colorectal cancer and19samples of multiple primary colorectalcarcinomas (7synchronous colorectal carcinomas and12metachronouscolorectal carcinomas) were involved in the study. Firstly clinicopathologicfeatures of different patients in diverse groups were collected and analyzed.2．DNAwas obtained fromparaffin sectionand operational samples ofdifferent patients, then exon5-8of P53gene and codon12-13of K-ras gene were extended by real-time PCR. The PCR productions were automaticallysequenced for gene mutation analysis, then compare the results with eachother.3．Multi-factor correlation analysis was carried out between theclinicopathologic features and the mutation of P53and K-ras gene of thecolorectal adenomas and primary colorectal cancers.Results1．The P53gene mutation is0%(0/25)，44.8%（17/38），43.6%（34/78）and42.1%（8/19）respectively in normal mucosa tissue, colorectaladenomas,primary colorectal cancers and multiple primary colorectal carcinomas,while the proportionof K-ras gene mutation is0%（0/25），18.4%（7/38），39.7%（31/78），47.4%（9/19）respectively.2．In our investigation there were obvious statistical differences as tothe proportion of mutation of the P53and K-ras gene between normalmucosa tissue and other three groups (P＜0.05）, while statisticaldifferencesas to the proportion of mutation of K-ras gene found between colorectaladenomas group and primary colorectal cancers group, multiple primarycolorectal carcinomas group(P＜0.05）. There was significant statisticaldeference between P53and K-ras gene mutation in colorectal adenomas(P＜0.05）.3．There were no statisticaldifferences as to the proportionof mutation of the P53and K-ras gene between the stageⅠ,Ⅱand well-differentiatedones of primary colorectal cancers and the stage Ⅲ Ⅳ andpoorly-differentiated ones.4．There was no relationship between the age, gender, family historyand tumor locations of the patients and the mutation of the P53and K-rasgene of the colorectal adenomas and primary colorectal cancers, moreover,there was no association between the stage and grade of differentiation ofcancer and the mutation of the P53and K-ras gene of the primary colorectalcancers.Conclusion1．The results of this study suggested that P53and K-ras gene hadmutated in the procedure of colorectal tumorigenesis.2．The results of this research also indicated that the mutation of P53gene occurs earlier than K-ras mutation during tumorigenesis.3．The age, gender, family history and tumor locations are not theindependent risk factors of the mutation of the P53and K-ras gene of thecolorectal adenomas and primary colorectal cancers, moreover, the stageand grade of differentiation of cancer was not the independent risky factorsof the mutation of the P53and K-ras gene of the primary colorectal cancers.