AIM:To investigate aberrant DNA methylation of CpG islands and subsequent low-or high-level DNA microsatellite instability(MSI)which is assumed to drive colon carcinogenesis. METHODS:DNA of healthy individuals,adenoma...AIM:To investigate aberrant DNA methylation of CpG islands and subsequent low-or high-level DNA microsatellite instability(MSI)which is assumed to drive colon carcinogenesis. METHODS:DNA of healthy individuals,adenoma(tu-bular or villous/tubulovillous)patients,and colorectal carcinoma patients who underwent colonoscopy was used for assessing the prevalence of aberrant DNA methylation of human DNA mismatch repair gene mutator L homologue 1(hMLH1),Cyclin-dependent kinase inhibitor 2A(CDKN2A/p16),and O-6-methylguanine DNA methyltransferase(MGMT),as well as their rela- tion to MSI. RESULTS:The frequency of promoter methylation for each locus increased in the sequence healthy tissue/adenoma/carcinoma.MGMT showed the highest frequency in each group.MGMT and CDKN2A/p16 presented a statistically significant increase in promoter methylation between the less and more tumorigenic forms of colorectal adenomas(tubular vs tubullovillous and villous adenomas).All patients with tubulovillous/villous adenomas,as well as all colorectal cancer patients,showed promoter methylation in at least one of the examined loci.These findings suggest a potentially crucial role for methylation in the polyp/adenoma to cancer progres- sion in colorectal carcinogenesis.MSI and methylation seem to be interdependent,as simultaneous hMLH1, CDKN2A/p16,and MGMT promoter methylation was present in 8/9 colorectal cancer patients showing the MSI phenotype. CONCLUSION:Methylation analysis of hMLH1,CD- KN2A/p16,and MGMT revealed specific methylation profiles for tubular adenomas,tubulovillous/villous adenomas,and colorectal cancers,supporting the use of these alterations in assessment of colorectal tumorigenesis.展开更多
BACKGROUND The development of colorectal cancer(CRC) is a complicated multistep process that involves an accumulation of mutations in tumor suppressor genes and oncogenes.In the process of DNA replication, base mismat...BACKGROUND The development of colorectal cancer(CRC) is a complicated multistep process that involves an accumulation of mutations in tumor suppressor genes and oncogenes.In the process of DNA replication, base mismatch often occurs due to various factors leading to abnormal expression of mismatch repair genes(MMR),among which MLH1 and MSH2 are the most important.Recently, numerous studies indicated that MLH1/MSH2 phenotype is associated with CRC.We wanted to elucidate the role of MLH1/MSH2 in the prediction and prognosis of CRC through long-term clinical observation.AIM To evaluate the prognostic and predictive significance of MLH1/MSH2 in patients with stage Ⅱ-Ⅲ CRC using immunohistochemical analysis and GeneScan.METHODS Specimens from 681 patients with CRC(395 stage Ⅱ and 286 stage Ⅲ, 387 males and 294 females) who underwent curative surgical resection from 2013 to 2016 were tested.Immunohistochemistry was used to analyze MMR status and the microsatellite status of 133 patients was determined by GeneScan analysis.RESULTS Five hundred and fifty(80.76%) patients were MLH1/MSH2 positive and 131(19.24%) were negative by immunohistochemistry.MLH1/MSH2-positive tumors were significantly more frequent in the colon than in the rectum, and had poor differentiation and less mucin production(P < 0.05).Patients of different groups did not differ in terms of age, gender, tumor size, tumor stage, lymphocytic infiltration, or circumscribed margin.MLH1/MSH2-negative patients had a more favorable OS than MLH1/MSH2-positive patients(P < 0.001).Univariate and multivariate analyses demonstrated MLH1/MSH2 expression as an independent prognostic and predictive factor for stage Ⅱ/Ⅲ CRC.MLH1/MSH2 expression was a strong prognostic factor in all patients [P < 0.001, hazard ratio(HR) = 4.064,95%CI: 2.241–7.369].Adjuvant chemotherapy had a greater correlation with survival advantage in MLH1/MSH2-negative patients with stage Ⅲ disease(P <0.001, HR = 7.660, 95%CI: 2.974–15.883).However, patients with stage Ⅱ disease or MLH1/MSH2-positive patients with stage Ⅲ disease did not benefit from adjuvant chemotherapy.GeneScan analysis demonstrated that among 133 patients, 105(78.95%) were microsatellite stable, and 28(21.05%) had microsatellite instability(MSI), including 18(13.53%) with high MSI and 10(7.52%) with low MSI.This is consistent with the immunohistochemical results.CONCLUSION MLH1/MSH2 phenotype constitutes a pathologically and clinically distinct subtype of sporadic CRC.MLH1/MSH2 is an independent prognostic and predictive factor for outcome of stage Ⅱ-Ⅲ CRC.展开更多
基金Supported by A 2-year grant of the Greek Ministry of Health and Welfare,No.111K/56
文摘AIM:To investigate aberrant DNA methylation of CpG islands and subsequent low-or high-level DNA microsatellite instability(MSI)which is assumed to drive colon carcinogenesis. METHODS:DNA of healthy individuals,adenoma(tu-bular or villous/tubulovillous)patients,and colorectal carcinoma patients who underwent colonoscopy was used for assessing the prevalence of aberrant DNA methylation of human DNA mismatch repair gene mutator L homologue 1(hMLH1),Cyclin-dependent kinase inhibitor 2A(CDKN2A/p16),and O-6-methylguanine DNA methyltransferase(MGMT),as well as their rela- tion to MSI. RESULTS:The frequency of promoter methylation for each locus increased in the sequence healthy tissue/adenoma/carcinoma.MGMT showed the highest frequency in each group.MGMT and CDKN2A/p16 presented a statistically significant increase in promoter methylation between the less and more tumorigenic forms of colorectal adenomas(tubular vs tubullovillous and villous adenomas).All patients with tubulovillous/villous adenomas,as well as all colorectal cancer patients,showed promoter methylation in at least one of the examined loci.These findings suggest a potentially crucial role for methylation in the polyp/adenoma to cancer progres- sion in colorectal carcinogenesis.MSI and methylation seem to be interdependent,as simultaneous hMLH1, CDKN2A/p16,and MGMT promoter methylation was present in 8/9 colorectal cancer patients showing the MSI phenotype. CONCLUSION:Methylation analysis of hMLH1,CD- KN2A/p16,and MGMT revealed specific methylation profiles for tubular adenomas,tubulovillous/villous adenomas,and colorectal cancers,supporting the use of these alterations in assessment of colorectal tumorigenesis.
基金Supported by Medical Science and Technology Development Foundation,Nanjing Department of Health,No.YKK14140(to ShuiMing Wang)and No.ZKX15040(to Bin Jiang)Project of Administration of Traditional Chinese Medicine of Jiangsu Province of China,No.LZ11101(to Zhi-Ming Fang)
文摘BACKGROUND The development of colorectal cancer(CRC) is a complicated multistep process that involves an accumulation of mutations in tumor suppressor genes and oncogenes.In the process of DNA replication, base mismatch often occurs due to various factors leading to abnormal expression of mismatch repair genes(MMR),among which MLH1 and MSH2 are the most important.Recently, numerous studies indicated that MLH1/MSH2 phenotype is associated with CRC.We wanted to elucidate the role of MLH1/MSH2 in the prediction and prognosis of CRC through long-term clinical observation.AIM To evaluate the prognostic and predictive significance of MLH1/MSH2 in patients with stage Ⅱ-Ⅲ CRC using immunohistochemical analysis and GeneScan.METHODS Specimens from 681 patients with CRC(395 stage Ⅱ and 286 stage Ⅲ, 387 males and 294 females) who underwent curative surgical resection from 2013 to 2016 were tested.Immunohistochemistry was used to analyze MMR status and the microsatellite status of 133 patients was determined by GeneScan analysis.RESULTS Five hundred and fifty(80.76%) patients were MLH1/MSH2 positive and 131(19.24%) were negative by immunohistochemistry.MLH1/MSH2-positive tumors were significantly more frequent in the colon than in the rectum, and had poor differentiation and less mucin production(P < 0.05).Patients of different groups did not differ in terms of age, gender, tumor size, tumor stage, lymphocytic infiltration, or circumscribed margin.MLH1/MSH2-negative patients had a more favorable OS than MLH1/MSH2-positive patients(P < 0.001).Univariate and multivariate analyses demonstrated MLH1/MSH2 expression as an independent prognostic and predictive factor for stage Ⅱ/Ⅲ CRC.MLH1/MSH2 expression was a strong prognostic factor in all patients [P < 0.001, hazard ratio(HR) = 4.064,95%CI: 2.241–7.369].Adjuvant chemotherapy had a greater correlation with survival advantage in MLH1/MSH2-negative patients with stage Ⅲ disease(P <0.001, HR = 7.660, 95%CI: 2.974–15.883).However, patients with stage Ⅱ disease or MLH1/MSH2-positive patients with stage Ⅲ disease did not benefit from adjuvant chemotherapy.GeneScan analysis demonstrated that among 133 patients, 105(78.95%) were microsatellite stable, and 28(21.05%) had microsatellite instability(MSI), including 18(13.53%) with high MSI and 10(7.52%) with low MSI.This is consistent with the immunohistochemical results.CONCLUSION MLH1/MSH2 phenotype constitutes a pathologically and clinically distinct subtype of sporadic CRC.MLH1/MSH2 is an independent prognostic and predictive factor for outcome of stage Ⅱ-Ⅲ CRC.
