DNA mismatch repair guards the integrity of the genome of almost all organisms by correcting DNA biosynthetic errors and by ensuring the fidelity of homologous genetic recombination. MutL is one of the important prote...DNA mismatch repair guards the integrity of the genome of almost all organisms by correcting DNA biosynthetic errors and by ensuring the fidelity of homologous genetic recombination. MutL is one of the important proteins involved in mismatch repair system. It has been suggested to function as a master coordinator or molecular matchmaker because it interacts physically with MutS, the endonuclease MutH, and DNA helicase UvrD. It also binds to DNA and has an ATPase activity. MutL defective bacteria strains have elevated mutation rates and it has been reported recently that MutL defect may have an important impact on bacterial evolution.展开更多
DNA mismatch repair （MMR） is a highly conserved biological pathway that plays a key role in maintaining genomic stability. The specificity of MMR is primarily for base-base mismatches and insertion/deletion mispairs...DNA mismatch repair （MMR） is a highly conserved biological pathway that plays a key role in maintaining genomic stability. The specificity of MMR is primarily for base-base mismatches and insertion/deletion mispairs generated during DNA replication and recombination. MMR also suppresses homeologous recombination and was recently shown to play a role in DNA damage signaling in eukaryotic cells. Escherichia coli MutS and MutL and their eukaryotic homologs, MutSα and MutLα, respectively, are key players in MMR-associated genome maintenance. Many other protein components that participate in various DNA metabolic pathways, such as PCNA and RPA, are also essential for MMR. Defects in MMR are associated with genome-wide instability, predisposition to certain types of cancer including hereditary non-polyposis colorectal cancer, resistance to certain chemotherapeutic agents, and abnormalities in meiosis and sterility in mammalian systems.展开更多
目的:通过观察健脾活血方对胃癌前病变大鼠胃黏膜组织中CD44V6、MLH1及MSH2表达的影响,探讨健脾活血方对其干预的作用机制.方法:除正常组外,其他大鼠采用以N-甲基-N-硝基-N-亚硝基胍(N-methyl-N-nitro N-nitrosoguanidine,MNNG)为主同...目的:通过观察健脾活血方对胃癌前病变大鼠胃黏膜组织中CD44V6、MLH1及MSH2表达的影响,探讨健脾活血方对其干预的作用机制.方法:除正常组外,其他大鼠采用以N-甲基-N-硝基-N-亚硝基胍(N-methyl-N-nitro N-nitrosoguanidine,MNNG)为主同时配合0.3g/L雷尼替丁、400 mL/L乙醇及饥饱失常的多因素造模法建立胃癌前病变动物模型.将造模成功的40只大鼠随机分为模型组(0.9%氯化钠溶液)、胃复春组(0.86 g/kg)、健脾活血方高、中、低剂量组(32、16、8 g/kg),每组8只,每组每天给予等量(10 mL/kg)的不同药物灌胃一次,连续10 wk.实验末处死大鼠,给予相应处理后,快速免疫组织化学检测CD44V6、MLH1及MSH2表达情况.结果:模型组CD44V6表达与正常组相比明显升高(5.12±1.96 vs 0.25±0.46,P<0.01);健脾活血方高、中剂量组CD44V6表达与模型组相比均明显降低(2.25±0.71,3.25±0.31vs 5.12±1.96,P<0.01或P<0.05),低剂量组C D44V6表达与模型组比较差异无统计学意义(P>0.05);健脾活血方高剂量组CD44V6表达与胃复春组相比明显降低(2.25±0.71 vs4.62±1.19,P<0.01),中、低剂量组CD44V6表达与胃复春组比较差异无统计学意义(P>0.05).模型组MLH1、MSH2表达与正常组相比均明显降低(3.75±1.04 vs 8.00±0.926;3.62±1.69 vs 7.25±2.12,P<0.01);健脾活血方高、中、低剂量组MLH1、MSH2表达与模型组相比均明显升高(6.50±0.93,5.25±1.49,5.12±1.25 vs 3.75±1.04;6.62±2.13,6.00±1.51,5.50±1.41 vs 3.62±1.69,P<0.01或P<0.05);健脾活血方高剂量组MLH1表达与胃复春组相比明显升高(6.50±0.93 vs 4.88±1.25,P<0.05),中、低剂量组MLH1及高、中、低剂量组MSH2表达与胃复春组比较差异无统计学意义(P>0.05).结论:健脾活血方可通过降低CD44V6表达,上调MLH1、MSH2表达,减少细胞的非正常侵袭和转移,增强基因的错配修复功能,减少细胞的异常增殖和分化,发挥对大鼠胃癌前病变的治疗作用.展开更多
AIM： To establish and validate the mutation testing for identification and characterization of hereditary non-polyposis colorectal cancer （HNPCC） in suspected Chinese patients. METHODS： Five independent Chinese ki...AIM： To establish and validate the mutation testing for identification and characterization of hereditary non-polyposis colorectal cancer （HNPCC） in suspected Chinese patients. METHODS： Five independent Chinese kindreds with HNPCC fulfilling the classical Amsterdam criteria were collected. Genomic DNA was extracted after informed consent was obtained. The coding region of hMSH2 and hMLH1 genes was detected by polymerase chain reaction （PCR） and denaturing high-performance liquid chromatography （DHPLC）. Mutations identified in the proband by DHPLC were directly sequenced using a 377 DNA sequencer, analyzed with a basic local alignment tool （BLAST）, and tested in the corresponding family members by direct DNA sequencing. RESULTS： Mutations were identified in two Chinese HNPCC kindreds. One was the missense mutation of hMSH2 c.1808A→G resulting in Asp 603 Gly identified in the proband of the fifth HNPCC （HNPCCS） kindred. In the HNP5 kindred, three family members were found to have this mutation and two of them had colorectal cancer. The other mutation of hMLH1 c.1882A→G was identified in the HNP2 kindred＇s proband, which might be the nonsense mutation analyzed by BLAST. CONCLUSION： Pedigree investigation and mutation testing of hMSH2 and hMLH1 are the practical methods to identify high-risk HNPCC patients in China.展开更多
文摘DNA mismatch repair guards the integrity of the genome of almost all organisms by correcting DNA biosynthetic errors and by ensuring the fidelity of homologous genetic recombination. MutL is one of the important proteins involved in mismatch repair system. It has been suggested to function as a master coordinator or molecular matchmaker because it interacts physically with MutS, the endonuclease MutH, and DNA helicase UvrD. It also binds to DNA and has an ATPase activity. MutL defective bacteria strains have elevated mutation rates and it has been reported recently that MutL defect may have an important impact on bacterial evolution.
文摘DNA mismatch repair （MMR） is a highly conserved biological pathway that plays a key role in maintaining genomic stability. The specificity of MMR is primarily for base-base mismatches and insertion/deletion mispairs generated during DNA replication and recombination. MMR also suppresses homeologous recombination and was recently shown to play a role in DNA damage signaling in eukaryotic cells. Escherichia coli MutS and MutL and their eukaryotic homologs, MutSα and MutLα, respectively, are key players in MMR-associated genome maintenance. Many other protein components that participate in various DNA metabolic pathways, such as PCNA and RPA, are also essential for MMR. Defects in MMR are associated with genome-wide instability, predisposition to certain types of cancer including hereditary non-polyposis colorectal cancer, resistance to certain chemotherapeutic agents, and abnormalities in meiosis and sterility in mammalian systems.
文摘目的:通过观察健脾活血方对胃癌前病变大鼠胃黏膜组织中CD44V6、MLH1及MSH2表达的影响,探讨健脾活血方对其干预的作用机制.方法:除正常组外,其他大鼠采用以N-甲基-N-硝基-N-亚硝基胍(N-methyl-N-nitro N-nitrosoguanidine,MNNG)为主同时配合0.3g/L雷尼替丁、400 mL/L乙醇及饥饱失常的多因素造模法建立胃癌前病变动物模型.将造模成功的40只大鼠随机分为模型组(0.9%氯化钠溶液)、胃复春组(0.86 g/kg)、健脾活血方高、中、低剂量组(32、16、8 g/kg),每组8只,每组每天给予等量(10 mL/kg)的不同药物灌胃一次,连续10 wk.实验末处死大鼠,给予相应处理后,快速免疫组织化学检测CD44V6、MLH1及MSH2表达情况.结果:模型组CD44V6表达与正常组相比明显升高(5.12±1.96 vs 0.25±0.46,P<0.01);健脾活血方高、中剂量组CD44V6表达与模型组相比均明显降低(2.25±0.71,3.25±0.31vs 5.12±1.96,P<0.01或P<0.05),低剂量组C D44V6表达与模型组比较差异无统计学意义(P>0.05);健脾活血方高剂量组CD44V6表达与胃复春组相比明显降低(2.25±0.71 vs4.62±1.19,P<0.01),中、低剂量组CD44V6表达与胃复春组比较差异无统计学意义(P>0.05).模型组MLH1、MSH2表达与正常组相比均明显降低(3.75±1.04 vs 8.00±0.926;3.62±1.69 vs 7.25±2.12,P<0.01);健脾活血方高、中、低剂量组MLH1、MSH2表达与模型组相比均明显升高(6.50±0.93,5.25±1.49,5.12±1.25 vs 3.75±1.04;6.62±2.13,6.00±1.51,5.50±1.41 vs 3.62±1.69,P<0.01或P<0.05);健脾活血方高剂量组MLH1表达与胃复春组相比明显升高(6.50±0.93 vs 4.88±1.25,P<0.05),中、低剂量组MLH1及高、中、低剂量组MSH2表达与胃复春组比较差异无统计学意义(P>0.05).结论:健脾活血方可通过降低CD44V6表达,上调MLH1、MSH2表达,减少细胞的非正常侵袭和转移,增强基因的错配修复功能,减少细胞的异常增殖和分化,发挥对大鼠胃癌前病变的治疗作用.
基金The Special Funds of China Education Ministry for Returnees, No. 2003-14
文摘AIM： To establish and validate the mutation testing for identification and characterization of hereditary non-polyposis colorectal cancer （HNPCC） in suspected Chinese patients. METHODS： Five independent Chinese kindreds with HNPCC fulfilling the classical Amsterdam criteria were collected. Genomic DNA was extracted after informed consent was obtained. The coding region of hMSH2 and hMLH1 genes was detected by polymerase chain reaction （PCR） and denaturing high-performance liquid chromatography （DHPLC）. Mutations identified in the proband by DHPLC were directly sequenced using a 377 DNA sequencer, analyzed with a basic local alignment tool （BLAST）, and tested in the corresponding family members by direct DNA sequencing. RESULTS： Mutations were identified in two Chinese HNPCC kindreds. One was the missense mutation of hMSH2 c.1808A→G resulting in Asp 603 Gly identified in the proband of the fifth HNPCC （HNPCCS） kindred. In the HNP5 kindred, three family members were found to have this mutation and two of them had colorectal cancer. The other mutation of hMLH1 c.1882A→G was identified in the HNP2 kindred＇s proband, which might be the nonsense mutation analyzed by BLAST. CONCLUSION： Pedigree investigation and mutation testing of hMSH2 and hMLH1 are the practical methods to identify high-risk HNPCC patients in China.
