AIM:To investigate human epidermal growth factor receptor 2(HER2)-phosphatidylinositol 3-kinase(PI3K)-vAkt murine thymoma viral oncogene homolog signaling pathway.METHODS:We analyzed 231 formalin-fixed,paraffinembedde...AIM:To investigate human epidermal growth factor receptor 2(HER2)-phosphatidylinositol 3-kinase(PI3K)-vAkt murine thymoma viral oncogene homolog signaling pathway.METHODS:We analyzed 231 formalin-fixed,paraffinembedded gastric cancer tissue specimens from Japanese patients who had undergone surgical treatment.The patients' age,sex,tumor location,depth of invasion,pathological type,lymph node metastasis,and pathological stage were determined by a review of the medical records.Expression of HER2 was analyzed by immunohistochemistry(IHC) using the HercepTest TM kit.Standard criteria for HER2 positivity(0,1+,2+,and 3+) were used.Tumors that scored 3+ were considered HER2-positive.Expression of phospho Akt(pAkt) was also analyzed by IHC.Tumors were considered pAkt-positive when the percentage of positive tumor cells was 10% or more.PI3K,catalytic,alpha polypeptide(PIK3CA) mutations in exons 1,9 and 20 were analyzed by pyrosequencing.Epstein-Barr virus(EBV) infection was analyzed by in situ hybridization targeting EBV-encoded small RNA(EBER) with an EBER-RNA probe.Microsatellite instability(MSI) was analyzed by polymerase chain reaction using the mononucleotide markers BAT25 and BAT26.RESULTS:HER2 expression levels of 0,1+,2+ and 3+ were found in 167(72%),32(14%),12(5%) and 20(8.7%) samples,respectively.HER2 overexpression(IHC 3+) significantly correlated with intestinal histological type(15/20 vs 98 /205,P = 0.05).PIK3CA mutations were present in 20 cases(8.7%) and significantly correlated with MSI(10/20 vs 9/211,P < 0.01).The mutation frequency was high(21%) in T4 cancers and very low(6%) in T2 cancers.Mutations in exons 1,9 and 20 were detected in 5(2%),9(4%) and 7(3%) cases,respectively.Two new types of PIK3CA mutation,R88Q and R108H,were found in exon1.All PIK3CA mutations were heterozygous missense singlebase substitutions,the most common being H1047R(6/20,30%) in exon20.Eighteen cancers(8%) were EBV-positive and this positivity significantly correlated with a diffuse histological type(13/18 vs 93/198,P = 0.04).T展开更多
The KRAS oncogene is mutated in approximately 35%-45% of colorectal cancers, and KRAS mutational status testing has been highlighted in recent years. The most frequent mutations in this gene, point substitutions in co...The KRAS oncogene is mutated in approximately 35%-45% of colorectal cancers, and KRAS mutational status testing has been highlighted in recent years. The most frequent mutations in this gene, point substitutions in codons 12 and 13, were validated as negative predictors of response to anti-epidermal growth factor receptor antibodies. Therefore, determining the KRAS mutational status of tumor samples has become an essential tool for managing patients with colorectal cancers. Currently, a variety of detection methods have been established to analyze the mutation status in the key regions of the KRAS gene; however, several challenges remain related to standardized and uniform testing, including the selection of tumor samples, tumor sample processing and optimal testing methods. Moreover, new testing strategies, in combination with the mutation analysis of BRAF , PIK3CA and loss of PTEN proposed by many researchers and pathologists, should be promoted. In addition, we recommend that microsatellite instability, a prognostic factor, be added to the abovementioned concomitant analysis. This review provides an overview of KRAS biology and the recent advances in KRAS mutation testing. This review also addresses other aspects of status testing for determining the appropriate treatment and offers insight into the potential drawbacks of mutational testing.展开更多
Gastric cancer is one of the leading causes of cancerrelated deaths worldwide, although the incidence has gradually decreased in many Western countries. Two main gastric cancer histotypes, intestinal and diffuse, are ...Gastric cancer is one of the leading causes of cancerrelated deaths worldwide, although the incidence has gradually decreased in many Western countries. Two main gastric cancer histotypes, intestinal and diffuse, are recognised. Although most of the described genetic alterations have been observed in both types, different genetic pathways have been hypothesized. Genetic and epigenetic events, including 1q loss of heterozygosity (LOH), microsatellite instability and hypermethylation, have mostly been reported in intestinal-type gastric carcinoma and its precursor lesions, whereas 17p LOH, mutation or loss of E-cadherin are more often implicated in the development of diffuse-type gastric cancer.In this review, we summarize the sometimes contradictory findings regarding those markers which influence the progression of gastric adenocarcinoma.展开更多
Colorectal cancer(CRC) is the second most common cancer in women and the third most common in men globally. CRC arises from one or a combination of chromosomal instability, Cp G island methylator phenotype, and micros...Colorectal cancer(CRC) is the second most common cancer in women and the third most common in men globally. CRC arises from one or a combination of chromosomal instability, Cp G island methylator phenotype, and microsatellite instability. Genetic instability is usually caused by aneuploidy and loss of heterozygosity. Mutations in the tumor suppressor or cell cycle genes may also lead to cellular transformation. Similarly, epigenetic and/or genetic alterations resulting in impaired cellular pathways, such as DNA repair mechanism, may lead to microsatellite instability and mutator phenotype. Non-coding RNAs, more importantly micro RNAs and long non-coding RNAs have also been implicated at various CRC stages. Understanding the specific mechanisms of tumorigenesis and the underlying genetic and epigenetic traits is critical in comprehending the disease phenotype. This paper reviews these mechanisms along with the roles of various non-coding RNAs in CRCs.展开更多
There is an increasing understanding of the roles that microsatellite instability （MSI） plays in Lynch syndrome （by mutations） and sporadic （by mainly epigenetic changes） gastrointestinal （GI） and other cancer...There is an increasing understanding of the roles that microsatellite instability （MSI） plays in Lynch syndrome （by mutations） and sporadic （by mainly epigenetic changes） gastrointestinal （GI） and other cancers. Defi- cient DNA mismatch repair （MMR） results in the strong mutator phenotype known as MSI, which is the hall- mark of cancers arising within Lynch syndrome. MSI is characterized by length alterations within simple repeated sequences called microsatellites. Lynch syn- drome occurs primarily because of germline mutations in one of the MMR genes, mainly MLH1 or MSH2, less frequently MSH6, and rarely PMS2. MSI is also observed in about 15% of sporadic colorectal, gastric, and en-dometrial cancers and in lower frequencies in a minor- ity of other cancers where it is often associated with the hypermethylation of the IVlLH1 gene. miRNAs are small noncoding RNAs that regulate gene expression at the posttranscriptional level and are critical in many biological processes and cellular pathways. There is accumulating evidence to support the notion that the interrelationship between MSI and miRNA plays a key role in the pathogenesis of GI cancer. As a possible new mechanism underlying MSI, overexpression of m/R-IEE has been shown to downregulate expression of MLH1, IVlSH2, and MSH6. Thus, a subset of MSI-positive （MSI＋） cancers without known MMR defects may result from m/R-1E5 overexpression. Target genes of frameshift mutation for MSI are involved in various cellular func- tions, such as DNA repair, cell signaling, and apoptosis. A novel class of target genes that included not only epi- genetic modifier genes, such as HDAC2, but also miRNA processing machinery genes, including TARBP2 and XPO5, were found to be mutated in MSI＋ GI cancers. Thus, a subset of MSI＋ colorectal cancers （CRCs） has been proposed to exhibit a mutated miRNA machinery phenotype. Genetic, epigenetic, and transcriptomic dif- ferences exist between MSI＋ and MSI- cancers. Mo- lecular signatures of miRNA expressio展开更多
Understanding of the mechanism of colorectal carcinogenesis has been gaining momentum for some years on account of its high incidence and impact on the lives of individuals affected. Different genetic abnormalities ha...Understanding of the mechanism of colorectal carcinogenesis has been gaining momentum for some years on account of its high incidence and impact on the lives of individuals affected. Different genetic abnormalities have been found in colorectal cancers from different sites. For example, proximal colon cancer is usually related to the nucleotide instability pathway, as microsatellite instability （MSI）. However, distal colon cancer is usually associated with specific chromosomal instability （CIN）. The development of cancer at the rectum, though similar to that at the colon, displays its own unique features. These differences might be partially attributed to different embryological development and physiological circumstances. Environmental factors such as diet and alcohol intake also differ in their role in the development of tumors in the three segments, proximal colon, distal colon, and rectum. ＂Proximal shift＂ of colon cancer has been known for some time, and survival rates of colorectal cancer are higher when rectal cancers are excluded, both of which emphasize the three different segments of coloreetal cancer and their different properties. Meanwhile, colonic and rectal cancers are distinctive therapeutic entities. The concept of three entities of coloreetal cancer may be important in designing clinical trails or therapeutic strategies. However, the dispute about the inconsistency of data coneerning the site-specific mechanism of eolorectal carcinoma does exist, and more evidence about molecular events of carcinogenesis and targeted therapy needs to be collected to definitely confirm the conception.展开更多
AIM： To disclose geographic differences in genetic changes involved in gallbladder carcinogenesis between two distinct high-incidence areas of Japan and Hungary. METHODS： We examined 42 cases of gallbladder carcinom...AIM： To disclose geographic differences in genetic changes involved in gallbladder carcinogenesis between two distinct high-incidence areas of Japan and Hungary. METHODS： We examined 42 cases of gallbladder carcinoma： 22 Japanese and 20 Hungarian cases, p53 mutations at exons 5 to 8 and K-ras mutations at codon 12 were tested by direct sequencing. Microsatellite instability was determined from fluorescent dye-labeled PCR amplifications of flve-microsatellite markers （BAT-25, BAT-26, D2S123, DSS346, and D17S250）. RESULTS： Mutations of p53 were detected in 11 of 22 Japanese cases and 6 of 18 Hungarian cases （11/22 vs 6/18, P = 0.348）. Transition at CpG sites was found in none of 11 Japanese cases and 2 of 6 Hungarian cases; the difference was marginally significant （0/11 vs 2/6,P = 0.110）. K-ras mutations were detected in only one of the Hungarian cases. Eight of 19 （42.1%） ]apanese cases were MSI-high （presence of novel peaks in more than one of the five loci analyzed）, whereas only 1 of 15 （6.7%） Hungarian cases was MSI-high （P = 0.047）. CONCLUSION： It appears that the p53 mutations and MSI differ in patients with gallbladder carcinoma between two distinct high-incidence areas. Geographic variation might exist in the process of gallbladder carcinogenesis.展开更多
AIM： To determine whether the telomerase activity is related to the Microsatellite instability （MSI） genetic pathway and whether it means a difference in the survival.METHODS： The population consisted of 97 colore...AIM： To determine whether the telomerase activity is related to the Microsatellite instability （MSI） genetic pathway and whether it means a difference in the survival.METHODS： The population consisted of 97 colorectal cancer patients. MSI determination was performed in accordance with the NCI criteria using PCR and Genescan. Telomerase activity was determined by the TRAP-assay, an ELISA procedure based on the amplification of telomeric repeat sequences.RESULTS： 6.2% showed high MSI （MSI-H）, 10.3% showed low MSI （MSI-L） and 83.5% did not show this alteration （MSS）. Positive telomerase activity was detected in 92.8% of the patients. 83.3% of MSI-H tumors showed positive telomerase against 93.8% of MSS tumors. In the overall survival analysis the absence of telomerase activity conferred a better prognosis.CONCLUSION： Previous works have shown that tumors which develop via the MSI pathway present a better prognosis. No link between telomerase activity and MSl status is observed, although sample sizes are small. Patients with telomerase negative tumors had better overall survival than patients with telomerase positive tumors.展开更多
Colorectal cancer （CRC） is caused by a series of genetic or epigenetic changes, and in the last decade there has been an increased awareness that there are multiple forms of colorectal cancer that develop through di...Colorectal cancer （CRC） is caused by a series of genetic or epigenetic changes, and in the last decade there has been an increased awareness that there are multiple forms of colorectal cancer that develop through different pathways. Microsatellite instability is involved in the genesis of about 15% of sporadic colorectal cancers and most of hereditary nonpolyposis cancers. Tumors with a high frequency of microsatellite instability tend to be diploid, to possess a mucinous histology, and to have a surrounding lymphoid reaction. They are more prevalent in the proximal colon and have a fast pass from polyp to cancer. Nevertheless, they are associated with longer survival than stage-matched tumors with microsateUite stability. Resistance of colorectal cancers with a high frequency of microsatellite instability to 5-fluorouracilbased chemotherapy is well established. Silencing the MLH1 gene expression by its promoter methylation stops the formation of MLH1 protein, and prevents the normal activation of the DNA repair gene. This is an important cause for genomic instability and cell proliferation to the point of colorectal cancer formation. Better knowledge of this process will have a huge impact on colorectal cancer management, prevention, treatment and prognosis.展开更多
AIM： To investigate endoscopic and clinicopathologic characteristics of early gastric cancer （EGC） according to microsatellite instability phenotype. METHODS： Data were retrospectively collected from a single tert...AIM： To investigate endoscopic and clinicopathologic characteristics of early gastric cancer （EGC） according to microsatellite instability phenotype. METHODS： Data were retrospectively collected from a single tertiary referral center. Of 981 EGC patients surgically treated between December 2003 and October 2007, 73 consecutive EGC patients with two or more microsatellite instability （MSI） mutation [high MSI （MSI-H）] and 146 consecutive EGC patients with one or no MSI mutation （non-MSI-H） were selected. The endoscopic and clinicopathologic features were compared between the MSI-H and non-MSI-H EGC groups.RESULTS： In terms of endoscopic characteristics, MSI-H EGCs more frequently presented with elevated pattern （OR 4.38, 95% Cl： 2.40-8.01, P 〈 0.001）, moderate- to-severe atrophy in the surrounding mucosa （OR 1.91, 95% CI： 1.05-3.47, P = 0.033）, antral location （OR 3.99, 95% CI： 2.12-7.52, P 〈 0.001） and synchronous le- sions, compared to non-MSI-H EGCs （OR 2.65, 95% CI： 1.16-6.07, P = 0.021）. Other significant clinicopatholog- ic characteristics of MSI-H EGC included predominance of female sex （OR 2.77, 95% CI： 1.53-4.99, P 〈 0.001）, older age （〉 70 years） （OR 3.30, 95% CI： 1.57-6.92, P = 0.002）, better histologic differentiation （OR 2.35, 95% Cl： 1.27-4.34, P = 0.007）, intestinal type by Lau- ren classification （OR 2.34, 95% CI： 1.15-4.76, P = 0.019）, absence of a signet ring cell component （OR 2.44, 95% CI： 1.02-5.86, P = 0.046）, presence of mu- cinous component （OR 5.06, 95% Cl： 1.27-20.17, P = 0.022）, moderate-to-severe lymphoid stromal reaction （OR 3.95, 95% CI： 1.59-9.80, P = 0.003）, and co-exist- ing underlying adenoma （OR 2.66, 95% CI： 1.43-4.95, P = 0.002）. CONCLUSION： MSI-H EGC is associated with unique endoscopic and clinicopathologic characteristics includ- ing frequent presentation in protruded type, co-exist- ing underlying adenoma, and synchronous lesions.展开更多
AIM:To examine the methylation status of the promoter region of the checkpoint with forkhead-associated and ring fi nger(CHFR) and microsatellite mutator status in 59 primary gastric cancers.METHODS:We investigated th...AIM:To examine the methylation status of the promoter region of the checkpoint with forkhead-associated and ring fi nger(CHFR) and microsatellite mutator status in 59 primary gastric cancers.METHODS:We investigated the promoter methylation of CHFR in 59 cases of gastric cancer using methylation-specifi c PCR.Five microsatellite loci were analyzed using high-intensity microsatellite analysis reported previously, and p53 gene mutations were investigated by direct sequencing.RESULTS:Twenty cases(33.9%) showed promoter methylation and no relation was observed with the clinicopathological factors.We found that the promoter methylation of CHFR was frequently accompanied with microsatellite instability(MIN).Seven of 20(35.0%) cases showed MIN in hypermethylation of the CHFR tumor, while three of 39(7.7%) cases showed MIN in the non-methylated CHFR tumor(P < 0.01).However, we failed to fi nd any relationship between CHFR methylation and p53 mutation status.CONCLUSION:The coordinated loss of both the mitotic check point function and mismatch repair system suggests the potential to overcome the cell cycle check point, which may lead to an accumulation of mutations.However, the p53 mutation was not related to hypermethylation of the CHFR promoter and MIN, which indicates that an abnormality in p53 occurs as an independent process from the mismatch repair deficiency in carcinogenesis.展开更多
Objective:Germline mutations in mismatch repair(MMR)genes cause Lynch syndrome(LS).LS is an inherited disease,and an important consequence of MMR deficiency is microsatellite instability(MSI)phenotype.MSI phenotype in...Objective:Germline mutations in mismatch repair(MMR)genes cause Lynch syndrome(LS).LS is an inherited disease,and an important consequence of MMR deficiency is microsatellite instability(MSI)phenotype.MSI phenotype influences the efficacy of5 fluorouracil(5-FU)chemotherapy.Reproducible,cost effective,and easy to perform laboratory tests are required to include MSI detection in routine laboratory practice.Evaluation of CAT25 as monomorphic short tandem repeat sequence enables CAT25 to be an efficient screening tool among hereditary nonpolyposis colorectal cancer(HNPCC)patients compared with other methods used currently.Methods:Based on Amsterdam II criteria,31 patients in 31 families were shortlisted from a total number of 1,659 colorectal cancer patients.MSI status was examined in these patients using CAT25 and a commercially available Promega MSI five-markerbased detection system as well as immunohistochemical(IHC)staining of four important MMR proteins.Patients were scored as high microsatellite instable(MSI-H),low(MSI-L),or stable(MSS).MSI status determined by CAT25 single mononucleotide marker was compared with that of five mononucleotide markers,Promega commercial kit,and IHC method.Results:MMR protein deficiency was observed on 7/31 probands using IHC methodology and 6/31 categorized as MSI-H using commercial kit or CAT25 single marker.The sensitivity and specificity of the CAT25 single marker were the same as those detected by five-marker Promega commercial kit in our patients.Conclusions:Based on our results,the performance of the CAT25 single mononucleotide marker for MSI status determination in our HNPCC patients is the same as that of the five-marker-based commercial kit.展开更多
AIM: To study the characteristics of mismatch repair gene mutation of Chinese hereditary non-polyposis colorectal cancer (HNPCC) and hMLH1 gene promoter methylation, and to improve the screening strategy and explore t...AIM: To study the characteristics of mismatch repair gene mutation of Chinese hereditary non-polyposis colorectal cancer (HNPCC) and hMLH1 gene promoter methylation, and to improve the screening strategy and explore the pertinent test methods. METHODS: A systematic analysis of 30 probands from HNPCC families in the north of China was performed by immunohistochemistry, microsatellite instability (MSI), gene mutation and methylation detection. RESULTS: High frequency microsatellite instability occurred in 25 probands (83.3%) of HNPCC family. Loss of hMLH1 and hMSH2 protein expression accounted for 88% of all microsatellite instability. Pathogenic muta-tion occurred in 14 samples and 3 novel mutational sites were discovered. Deletion of exons 1-6, 1-7 and 8 of hMSH2 was detected in 3 samples and no large fragment deletion was found in hMLH1. Of the 30 probands, hMLH1 gene promoter methylation occurred in 3 probands. The rate of gene micromutation detection combined with large fragment deletion detection was 46.7%-56.7%. The rate of the two methods in combination with methylation detection was 63.3%. CONCLUSION: Scientific and rational detection strategy can improve the detection rate of HNPCC. Based on traditional molecular genetics and combined with epigenetics, multiple detection methods can accurately diagnose HNPCC.展开更多
基金Supported by Grants-in-Aid for Scientific Research from the Ministry of Education,Culture,Sports,Science and Technology of Japan,to Yamamoto H and Shinomura Y
文摘AIM:To investigate human epidermal growth factor receptor 2(HER2)-phosphatidylinositol 3-kinase(PI3K)-vAkt murine thymoma viral oncogene homolog signaling pathway.METHODS:We analyzed 231 formalin-fixed,paraffinembedded gastric cancer tissue specimens from Japanese patients who had undergone surgical treatment.The patients' age,sex,tumor location,depth of invasion,pathological type,lymph node metastasis,and pathological stage were determined by a review of the medical records.Expression of HER2 was analyzed by immunohistochemistry(IHC) using the HercepTest TM kit.Standard criteria for HER2 positivity(0,1+,2+,and 3+) were used.Tumors that scored 3+ were considered HER2-positive.Expression of phospho Akt(pAkt) was also analyzed by IHC.Tumors were considered pAkt-positive when the percentage of positive tumor cells was 10% or more.PI3K,catalytic,alpha polypeptide(PIK3CA) mutations in exons 1,9 and 20 were analyzed by pyrosequencing.Epstein-Barr virus(EBV) infection was analyzed by in situ hybridization targeting EBV-encoded small RNA(EBER) with an EBER-RNA probe.Microsatellite instability(MSI) was analyzed by polymerase chain reaction using the mononucleotide markers BAT25 and BAT26.RESULTS:HER2 expression levels of 0,1+,2+ and 3+ were found in 167(72%),32(14%),12(5%) and 20(8.7%) samples,respectively.HER2 overexpression(IHC 3+) significantly correlated with intestinal histological type(15/20 vs 98 /205,P = 0.05).PIK3CA mutations were present in 20 cases(8.7%) and significantly correlated with MSI(10/20 vs 9/211,P < 0.01).The mutation frequency was high(21%) in T4 cancers and very low(6%) in T2 cancers.Mutations in exons 1,9 and 20 were detected in 5(2%),9(4%) and 7(3%) cases,respectively.Two new types of PIK3CA mutation,R88Q and R108H,were found in exon1.All PIK3CA mutations were heterozygous missense singlebase substitutions,the most common being H1047R(6/20,30%) in exon20.Eighteen cancers(8%) were EBV-positive and this positivity significantly correlated with a diffuse histological type(13/18 vs 93/198,P = 0.04).T
基金Supported by Science and Technology Commission of Shanghai Municipality, No. 10DJ1400501
文摘The KRAS oncogene is mutated in approximately 35%-45% of colorectal cancers, and KRAS mutational status testing has been highlighted in recent years. The most frequent mutations in this gene, point substitutions in codons 12 and 13, were validated as negative predictors of response to anti-epidermal growth factor receptor antibodies. Therefore, determining the KRAS mutational status of tumor samples has become an essential tool for managing patients with colorectal cancers. Currently, a variety of detection methods have been established to analyze the mutation status in the key regions of the KRAS gene; however, several challenges remain related to standardized and uniform testing, including the selection of tumor samples, tumor sample processing and optimal testing methods. Moreover, new testing strategies, in combination with the mutation analysis of BRAF , PIK3CA and loss of PTEN proposed by many researchers and pathologists, should be promoted. In addition, we recommend that microsatellite instability, a prognostic factor, be added to the abovementioned concomitant analysis. This review provides an overview of KRAS biology and the recent advances in KRAS mutation testing. This review also addresses other aspects of status testing for determining the appropriate treatment and offers insight into the potential drawbacks of mutational testing.
文摘Gastric cancer is one of the leading causes of cancerrelated deaths worldwide, although the incidence has gradually decreased in many Western countries. Two main gastric cancer histotypes, intestinal and diffuse, are recognised. Although most of the described genetic alterations have been observed in both types, different genetic pathways have been hypothesized. Genetic and epigenetic events, including 1q loss of heterozygosity (LOH), microsatellite instability and hypermethylation, have mostly been reported in intestinal-type gastric carcinoma and its precursor lesions, whereas 17p LOH, mutation or loss of E-cadherin are more often implicated in the development of diffuse-type gastric cancer.In this review, we summarize the sometimes contradictory findings regarding those markers which influence the progression of gastric adenocarcinoma.
文摘Colorectal cancer(CRC) is the second most common cancer in women and the third most common in men globally. CRC arises from one or a combination of chromosomal instability, Cp G island methylator phenotype, and microsatellite instability. Genetic instability is usually caused by aneuploidy and loss of heterozygosity. Mutations in the tumor suppressor or cell cycle genes may also lead to cellular transformation. Similarly, epigenetic and/or genetic alterations resulting in impaired cellular pathways, such as DNA repair mechanism, may lead to microsatellite instability and mutator phenotype. Non-coding RNAs, more importantly micro RNAs and long non-coding RNAs have also been implicated at various CRC stages. Understanding the specific mechanisms of tumorigenesis and the underlying genetic and epigenetic traits is critical in comprehending the disease phenotype. This paper reviews these mechanisms along with the roles of various non-coding RNAs in CRCs.
基金Supported by Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan
文摘There is an increasing understanding of the roles that microsatellite instability （MSI） plays in Lynch syndrome （by mutations） and sporadic （by mainly epigenetic changes） gastrointestinal （GI） and other cancers. Defi- cient DNA mismatch repair （MMR） results in the strong mutator phenotype known as MSI, which is the hall- mark of cancers arising within Lynch syndrome. MSI is characterized by length alterations within simple repeated sequences called microsatellites. Lynch syn- drome occurs primarily because of germline mutations in one of the MMR genes, mainly MLH1 or MSH2, less frequently MSH6, and rarely PMS2. MSI is also observed in about 15% of sporadic colorectal, gastric, and en-dometrial cancers and in lower frequencies in a minor- ity of other cancers where it is often associated with the hypermethylation of the IVlLH1 gene. miRNAs are small noncoding RNAs that regulate gene expression at the posttranscriptional level and are critical in many biological processes and cellular pathways. There is accumulating evidence to support the notion that the interrelationship between MSI and miRNA plays a key role in the pathogenesis of GI cancer. As a possible new mechanism underlying MSI, overexpression of m/R-IEE has been shown to downregulate expression of MLH1, IVlSH2, and MSH6. Thus, a subset of MSI-positive （MSI＋） cancers without known MMR defects may result from m/R-1E5 overexpression. Target genes of frameshift mutation for MSI are involved in various cellular func- tions, such as DNA repair, cell signaling, and apoptosis. A novel class of target genes that included not only epi- genetic modifier genes, such as HDAC2, but also miRNA processing machinery genes, including TARBP2 and XPO5, were found to be mutated in MSI＋ GI cancers. Thus, a subset of MSI＋ colorectal cancers （CRCs） has been proposed to exhibit a mutated miRNA machinery phenotype. Genetic, epigenetic, and transcriptomic dif- ferences exist between MSI＋ and MSI- cancers. Mo- lecular signatures of miRNA expressio
基金supported by the Program of Science and Technology in the National "Eleventh 5-year Plan" of China (No. 2006BAI0214)the Foundation of Science and Technology of Hangzhou City, China (No. 20061123B02)
文摘Understanding of the mechanism of colorectal carcinogenesis has been gaining momentum for some years on account of its high incidence and impact on the lives of individuals affected. Different genetic abnormalities have been found in colorectal cancers from different sites. For example, proximal colon cancer is usually related to the nucleotide instability pathway, as microsatellite instability （MSI）. However, distal colon cancer is usually associated with specific chromosomal instability （CIN）. The development of cancer at the rectum, though similar to that at the colon, displays its own unique features. These differences might be partially attributed to different embryological development and physiological circumstances. Environmental factors such as diet and alcohol intake also differ in their role in the development of tumors in the three segments, proximal colon, distal colon, and rectum. ＂Proximal shift＂ of colon cancer has been known for some time, and survival rates of colorectal cancer are higher when rectal cancers are excluded, both of which emphasize the three different segments of coloreetal cancer and their different properties. Meanwhile, colonic and rectal cancers are distinctive therapeutic entities. The concept of three entities of coloreetal cancer may be important in designing clinical trails or therapeutic strategies. However, the dispute about the inconsistency of data coneerning the site-specific mechanism of eolorectal carcinoma does exist, and more evidence about molecular events of carcinogenesis and targeted therapy needs to be collected to definitely confirm the conception.
文摘AIM： To disclose geographic differences in genetic changes involved in gallbladder carcinogenesis between two distinct high-incidence areas of Japan and Hungary. METHODS： We examined 42 cases of gallbladder carcinoma： 22 Japanese and 20 Hungarian cases, p53 mutations at exons 5 to 8 and K-ras mutations at codon 12 were tested by direct sequencing. Microsatellite instability was determined from fluorescent dye-labeled PCR amplifications of flve-microsatellite markers （BAT-25, BAT-26, D2S123, DSS346, and D17S250）. RESULTS： Mutations of p53 were detected in 11 of 22 Japanese cases and 6 of 18 Hungarian cases （11/22 vs 6/18, P = 0.348）. Transition at CpG sites was found in none of 11 Japanese cases and 2 of 6 Hungarian cases; the difference was marginally significant （0/11 vs 2/6,P = 0.110）. K-ras mutations were detected in only one of the Hungarian cases. Eight of 19 （42.1%） ]apanese cases were MSI-high （presence of novel peaks in more than one of the five loci analyzed）, whereas only 1 of 15 （6.7%） Hungarian cases was MSI-high （P = 0.047）. CONCLUSION： It appears that the p53 mutations and MSI differ in patients with gallbladder carcinoma between two distinct high-incidence areas. Geographic variation might exist in the process of gallbladder carcinogenesis.
基金grants from the Comunidad Autonoma de Madrid, Madrid, Spain, No. 08.1/0012/1999from the Fondo de Investigaciones Sanitarias, Spain, PI030514
文摘AIM： To determine whether the telomerase activity is related to the Microsatellite instability （MSI） genetic pathway and whether it means a difference in the survival.METHODS： The population consisted of 97 colorectal cancer patients. MSI determination was performed in accordance with the NCI criteria using PCR and Genescan. Telomerase activity was determined by the TRAP-assay, an ELISA procedure based on the amplification of telomeric repeat sequences.RESULTS： 6.2% showed high MSI （MSI-H）, 10.3% showed low MSI （MSI-L） and 83.5% did not show this alteration （MSS）. Positive telomerase activity was detected in 92.8% of the patients. 83.3% of MSI-H tumors showed positive telomerase against 93.8% of MSS tumors. In the overall survival analysis the absence of telomerase activity conferred a better prognosis.CONCLUSION： Previous works have shown that tumors which develop via the MSI pathway present a better prognosis. No link between telomerase activity and MSl status is observed, although sample sizes are small. Patients with telomerase negative tumors had better overall survival than patients with telomerase positive tumors.
文摘Colorectal cancer （CRC） is caused by a series of genetic or epigenetic changes, and in the last decade there has been an increased awareness that there are multiple forms of colorectal cancer that develop through different pathways. Microsatellite instability is involved in the genesis of about 15% of sporadic colorectal cancers and most of hereditary nonpolyposis cancers. Tumors with a high frequency of microsatellite instability tend to be diploid, to possess a mucinous histology, and to have a surrounding lymphoid reaction. They are more prevalent in the proximal colon and have a fast pass from polyp to cancer. Nevertheless, they are associated with longer survival than stage-matched tumors with microsateUite stability. Resistance of colorectal cancers with a high frequency of microsatellite instability to 5-fluorouracilbased chemotherapy is well established. Silencing the MLH1 gene expression by its promoter methylation stops the formation of MLH1 protein, and prevents the normal activation of the DNA repair gene. This is an important cause for genomic instability and cell proliferation to the point of colorectal cancer formation. Better knowledge of this process will have a huge impact on colorectal cancer management, prevention, treatment and prognosis.
文摘AIM： To investigate endoscopic and clinicopathologic characteristics of early gastric cancer （EGC） according to microsatellite instability phenotype. METHODS： Data were retrospectively collected from a single tertiary referral center. Of 981 EGC patients surgically treated between December 2003 and October 2007, 73 consecutive EGC patients with two or more microsatellite instability （MSI） mutation [high MSI （MSI-H）] and 146 consecutive EGC patients with one or no MSI mutation （non-MSI-H） were selected. The endoscopic and clinicopathologic features were compared between the MSI-H and non-MSI-H EGC groups.RESULTS： In terms of endoscopic characteristics, MSI-H EGCs more frequently presented with elevated pattern （OR 4.38, 95% Cl： 2.40-8.01, P 〈 0.001）, moderate- to-severe atrophy in the surrounding mucosa （OR 1.91, 95% CI： 1.05-3.47, P = 0.033）, antral location （OR 3.99, 95% CI： 2.12-7.52, P 〈 0.001） and synchronous le- sions, compared to non-MSI-H EGCs （OR 2.65, 95% CI： 1.16-6.07, P = 0.021）. Other significant clinicopatholog- ic characteristics of MSI-H EGC included predominance of female sex （OR 2.77, 95% CI： 1.53-4.99, P 〈 0.001）, older age （〉 70 years） （OR 3.30, 95% CI： 1.57-6.92, P = 0.002）, better histologic differentiation （OR 2.35, 95% Cl： 1.27-4.34, P = 0.007）, intestinal type by Lau- ren classification （OR 2.34, 95% CI： 1.15-4.76, P = 0.019）, absence of a signet ring cell component （OR 2.44, 95% CI： 1.02-5.86, P = 0.046）, presence of mu- cinous component （OR 5.06, 95% Cl： 1.27-20.17, P = 0.022）, moderate-to-severe lymphoid stromal reaction （OR 3.95, 95% CI： 1.59-9.80, P = 0.003）, and co-exist- ing underlying adenoma （OR 2.66, 95% CI： 1.43-4.95, P = 0.002）. CONCLUSION： MSI-H EGC is associated with unique endoscopic and clinicopathologic characteristics includ- ing frequent presentation in protruded type, co-exist- ing underlying adenoma, and synchronous lesions.
文摘AIM:To examine the methylation status of the promoter region of the checkpoint with forkhead-associated and ring fi nger(CHFR) and microsatellite mutator status in 59 primary gastric cancers.METHODS:We investigated the promoter methylation of CHFR in 59 cases of gastric cancer using methylation-specifi c PCR.Five microsatellite loci were analyzed using high-intensity microsatellite analysis reported previously, and p53 gene mutations were investigated by direct sequencing.RESULTS:Twenty cases(33.9%) showed promoter methylation and no relation was observed with the clinicopathological factors.We found that the promoter methylation of CHFR was frequently accompanied with microsatellite instability(MIN).Seven of 20(35.0%) cases showed MIN in hypermethylation of the CHFR tumor, while three of 39(7.7%) cases showed MIN in the non-methylated CHFR tumor(P < 0.01).However, we failed to fi nd any relationship between CHFR methylation and p53 mutation status.CONCLUSION:The coordinated loss of both the mitotic check point function and mismatch repair system suggests the potential to overcome the cell cycle check point, which may lead to an accumulation of mutations.However, the p53 mutation was not related to hypermethylation of the CHFR promoter and MIN, which indicates that an abnormality in p53 occurs as an independent process from the mismatch repair deficiency in carcinogenesis.
文摘Objective:Germline mutations in mismatch repair(MMR)genes cause Lynch syndrome(LS).LS is an inherited disease,and an important consequence of MMR deficiency is microsatellite instability(MSI)phenotype.MSI phenotype influences the efficacy of5 fluorouracil(5-FU)chemotherapy.Reproducible,cost effective,and easy to perform laboratory tests are required to include MSI detection in routine laboratory practice.Evaluation of CAT25 as monomorphic short tandem repeat sequence enables CAT25 to be an efficient screening tool among hereditary nonpolyposis colorectal cancer(HNPCC)patients compared with other methods used currently.Methods:Based on Amsterdam II criteria,31 patients in 31 families were shortlisted from a total number of 1,659 colorectal cancer patients.MSI status was examined in these patients using CAT25 and a commercially available Promega MSI five-markerbased detection system as well as immunohistochemical(IHC)staining of four important MMR proteins.Patients were scored as high microsatellite instable(MSI-H),low(MSI-L),or stable(MSS).MSI status determined by CAT25 single mononucleotide marker was compared with that of five mononucleotide markers,Promega commercial kit,and IHC method.Results:MMR protein deficiency was observed on 7/31 probands using IHC methodology and 6/31 categorized as MSI-H using commercial kit or CAT25 single marker.The sensitivity and specificity of the CAT25 single marker were the same as those detected by five-marker Promega commercial kit in our patients.Conclusions:Based on our results,the performance of the CAT25 single mononucleotide marker for MSI status determination in our HNPCC patients is the same as that of the five-marker-based commercial kit.
基金Supported by Beijing Natural Science Foundation, No. 7062064
文摘AIM: To study the characteristics of mismatch repair gene mutation of Chinese hereditary non-polyposis colorectal cancer (HNPCC) and hMLH1 gene promoter methylation, and to improve the screening strategy and explore the pertinent test methods. METHODS: A systematic analysis of 30 probands from HNPCC families in the north of China was performed by immunohistochemistry, microsatellite instability (MSI), gene mutation and methylation detection. RESULTS: High frequency microsatellite instability occurred in 25 probands (83.3%) of HNPCC family. Loss of hMLH1 and hMSH2 protein expression accounted for 88% of all microsatellite instability. Pathogenic muta-tion occurred in 14 samples and 3 novel mutational sites were discovered. Deletion of exons 1-6, 1-7 and 8 of hMSH2 was detected in 3 samples and no large fragment deletion was found in hMLH1. Of the 30 probands, hMLH1 gene promoter methylation occurred in 3 probands. The rate of gene micromutation detection combined with large fragment deletion detection was 46.7%-56.7%. The rate of the two methods in combination with methylation detection was 63.3%. CONCLUSION: Scientific and rational detection strategy can improve the detection rate of HNPCC. Based on traditional molecular genetics and combined with epigenetics, multiple detection methods can accurately diagnose HNPCC.
