AIM: To explore the association of methylation of the CpG island in the promotor of the p16 tumor suppressor gene with the clinicopathological characteristics of the colorectal cancers. METHODS: Methylation-specific P...AIM: To explore the association of methylation of the CpG island in the promotor of the p16 tumor suppressor gene with the clinicopathological characteristics of the colorectal cancers. METHODS: Methylation-specific PCR (MSP) was used to detect p16 methylation of 62 sporadic colorectal cancer specimens. RESULTS: p16 methylation was detected in 42% of the tumors.Dukes'staging was associated with p16 methylation status.p16 methylation occurred more frequently in Dukes'C and D patients (75.9%) than in Dukes'A and B patients (12.1%). CONCLUSION: p16 methylation plays a role in the carcinogenesis of a subset of colorectal cancer, and it might be linked to poor prognosis.展开更多
Objective: To explore whether methylation of the CpG island in the promoter of the p16 tumor suppressor gene was associated with clinicopathological characteristics of the colorectal cancer patients. Methods: Methylat...Objective: To explore whether methylation of the CpG island in the promoter of the p16 tumor suppressor gene was associated with clinicopathological characteristics of the colorectal cancer patients. Methods: Methylation-specific PCR (MSP) was used to detect p16 methylation of the colorectal cancer patients. Results: In 58 sporadic colorectal cancer, 43.1% of the tumors had detectable p16 methylation. Dukes’ stage was associated with p16 methylation status. Dukes C, D patients (75%) were more likely to contain methylated p16 compared with Dukes A, B patients (13.3%). Conclusion: p16 methylation plays a role in the carcinogenesis of a subset of colorectal cancer. P16 methylation might be considered as a prognostic indicator.展开更多
The tumor selectivity of alkylating agents that produce guanine O6-chloroethyl (laromustine and carmustine) and O6-methyl (temozolomide) lesions depends upon O6-methylguanine-DNA methyltransferase (MGMT) activity bein...The tumor selectivity of alkylating agents that produce guanine O6-chloroethyl (laromustine and carmustine) and O6-methyl (temozolomide) lesions depends upon O6-methylguanine-DNA methyltransferase (MGMT) activity being lower in tumor than in host tissue. Despite the established role of MGMT as a tumor resistance factor, consensus on how to assess MGMT expression in clinical samples is unsettled. The aim of this study is to examine the relationship between the values derived from distinctive MGMT measurements in 13, 12, 6 and 2 pairs of human tumors and matched normal adjacent tissue from the colon, kidney, lung and liver, respectively, and in human cell lines. The MGMT measurements included 1) alkyl-transfer assays using [benzene-3H]O6-benzylguanine as a substrate to assess functional MGMT activity, 2) methylation-specific PCR (MSP) to probe MGMT gene promoter CpG methylations as a measure of gene silencing, and 3) western immunoblots to analyze the MGMT protein. In human cell lines, a strict negative correlation existed between MGMT activity and the extent of promoter methylation. In tissue specimens, by contrast, the correlation between these two variables was low. Moreover, alkyl-transfer assays identified 3 pairs of tumors and normal tissue with tumor-selective reduction in MGMT activity in the absence of promoter methylation. Cell line MGMT migrated as a single band in western analyses, whereas tissue MGMT was heterogeneous around its molecular size and at much higher molecular masses, indicative of multi-layered post-translational modifications. Malignancy is occasionally associated with a mobility shift in MGMT. Contrary to the prevalent expectation that MGMT expression is governed at the level of gene silencing, these data suggest that other mechanisms that can lead to tumorselective reduction in MGMT activity exist in human tissue.展开更多
脂联素(Adiponectin)是至今发现的唯一与肥胖呈负相关的脂肪细胞特异性蛋白,是调控生物体的能量稳态、葡萄糖代谢和脂肪代谢的脂源性细胞因子之一。生物信息学分析发现,adiponectin基因启动子区-1500～-1350bp是CpG位点的富集区域。为...脂联素(Adiponectin)是至今发现的唯一与肥胖呈负相关的脂肪细胞特异性蛋白,是调控生物体的能量稳态、葡萄糖代谢和脂肪代谢的脂源性细胞因子之一。生物信息学分析发现,adiponectin基因启动子区-1500～-1350bp是CpG位点的富集区域。为了进一步研究脂联素基因的表达调控研究,文章从表观遗传学角度出发,通过Real-time PCR与甲基化特异性PCR(Methylation special PCR,MSP)的方法对脂联素基因的表达及其启动子区的甲基化状况进行了分析。结果表明,在adiponectin基因启动子区CG富集的区域(-1500～-1350bp)中,90日龄长白猪大多去甲基化(83%),90日龄蓝塘猪部分去甲基化(33%),成年蓝塘猪全是高度甲基化(100%),成年长白猪部分去甲基化(33%)。甲基化与去甲基化过程主要发生在某些特定CpG位点。脂联素基因在猪肌肉组织中以高度甲基化状态为主,这一结果与该基因在肌肉组织中表达量相吻合。以上结果提示,随个体发育,脂联素基因的甲基化状态随基因表达的波动呈现动态的过程,表现出与基因表达量波动基本一致的波动趋势。展开更多
基金Supported by the grants from Mjnistry of Public Health of China,No.98-1-303The Educational Committee of Shanghai,No.2000B02.
文摘AIM: To explore the association of methylation of the CpG island in the promotor of the p16 tumor suppressor gene with the clinicopathological characteristics of the colorectal cancers. METHODS: Methylation-specific PCR (MSP) was used to detect p16 methylation of 62 sporadic colorectal cancer specimens. RESULTS: p16 methylation was detected in 42% of the tumors.Dukes'staging was associated with p16 methylation status.p16 methylation occurred more frequently in Dukes'C and D patients (75.9%) than in Dukes'A and B patients (12.1%). CONCLUSION: p16 methylation plays a role in the carcinogenesis of a subset of colorectal cancer, and it might be linked to poor prognosis.
基金This work was supported by a grant from Ministry of Public Health of China (No. 98-1-303) and The Education Committee of Shanghai(No. l 2000B02).
文摘Objective: To explore whether methylation of the CpG island in the promoter of the p16 tumor suppressor gene was associated with clinicopathological characteristics of the colorectal cancer patients. Methods: Methylation-specific PCR (MSP) was used to detect p16 methylation of the colorectal cancer patients. Results: In 58 sporadic colorectal cancer, 43.1% of the tumors had detectable p16 methylation. Dukes’ stage was associated with p16 methylation status. Dukes C, D patients (75%) were more likely to contain methylated p16 compared with Dukes A, B patients (13.3%). Conclusion: p16 methylation plays a role in the carcinogenesis of a subset of colorectal cancer. P16 methylation might be considered as a prognostic indicator.
文摘The tumor selectivity of alkylating agents that produce guanine O6-chloroethyl (laromustine and carmustine) and O6-methyl (temozolomide) lesions depends upon O6-methylguanine-DNA methyltransferase (MGMT) activity being lower in tumor than in host tissue. Despite the established role of MGMT as a tumor resistance factor, consensus on how to assess MGMT expression in clinical samples is unsettled. The aim of this study is to examine the relationship between the values derived from distinctive MGMT measurements in 13, 12, 6 and 2 pairs of human tumors and matched normal adjacent tissue from the colon, kidney, lung and liver, respectively, and in human cell lines. The MGMT measurements included 1) alkyl-transfer assays using [benzene-3H]O6-benzylguanine as a substrate to assess functional MGMT activity, 2) methylation-specific PCR (MSP) to probe MGMT gene promoter CpG methylations as a measure of gene silencing, and 3) western immunoblots to analyze the MGMT protein. In human cell lines, a strict negative correlation existed between MGMT activity and the extent of promoter methylation. In tissue specimens, by contrast, the correlation between these two variables was low. Moreover, alkyl-transfer assays identified 3 pairs of tumors and normal tissue with tumor-selective reduction in MGMT activity in the absence of promoter methylation. Cell line MGMT migrated as a single band in western analyses, whereas tissue MGMT was heterogeneous around its molecular size and at much higher molecular masses, indicative of multi-layered post-translational modifications. Malignancy is occasionally associated with a mobility shift in MGMT. Contrary to the prevalent expectation that MGMT expression is governed at the level of gene silencing, these data suggest that other mechanisms that can lead to tumorselective reduction in MGMT activity exist in human tissue.
文摘脂联素(Adiponectin)是至今发现的唯一与肥胖呈负相关的脂肪细胞特异性蛋白,是调控生物体的能量稳态、葡萄糖代谢和脂肪代谢的脂源性细胞因子之一。生物信息学分析发现,adiponectin基因启动子区-1500～-1350bp是CpG位点的富集区域。为了进一步研究脂联素基因的表达调控研究,文章从表观遗传学角度出发,通过Real-time PCR与甲基化特异性PCR(Methylation special PCR,MSP)的方法对脂联素基因的表达及其启动子区的甲基化状况进行了分析。结果表明,在adiponectin基因启动子区CG富集的区域(-1500～-1350bp)中,90日龄长白猪大多去甲基化(83%),90日龄蓝塘猪部分去甲基化(33%),成年蓝塘猪全是高度甲基化(100%),成年长白猪部分去甲基化(33%)。甲基化与去甲基化过程主要发生在某些特定CpG位点。脂联素基因在猪肌肉组织中以高度甲基化状态为主,这一结果与该基因在肌肉组织中表达量相吻合。以上结果提示,随个体发育,脂联素基因的甲基化状态随基因表达的波动呈现动态的过程,表现出与基因表达量波动基本一致的波动趋势。
