[Gastric cancer and microsatellite instability].
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Adaptor Proteins, Signal Transducing↗
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Results for “DNA MICROSATELLITE INSTABILITY”
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Microsatellite instability in solitary and sporadic gastric cancer.
UNLABELLED: Recently, the presence of microsatellite instability (MSI) has been reported in gastric cancer and associated with older age of presentation, distal tumor location, early disease staging, and better overall prognosis. Different characteristics in presentation and in tumor behavior may be explained by different genetic alterations during carcinogenesis of gastric cancer. Identification of specific genetic pathways in gastric cancer may have direct impact on prognosis and selection of treatment strategies. PATIENTS AND METHODS: All 24 patients were treated by radical surgery. Fragments of normal and tumor tissues were extracted from the specimen and stored at -80 degrees C before DNA purification and extraction. PCR amplification utilizing microsatellite markers was performed. Tumors presenting PCR products of abnormal sizes were considered positive for microsatellite instability (MSI+). RESULTS: Five patients (21%) had tumors that were MSI+ in at least 1 marker. In the group of patients with Lauren's intestinal-type gastric carcinoma, 3 had tumors that were MSI+ (23%), while in the group of diffuse-type gastric cancer, 2 patients had tumors that were MSI+ (19%). The mean age of presentation and the male:female ratio was similar in both groups. Tumors that were MSI+ were more frequently located in proximal portion of the stomach compared to microsatellite-stable (MSS) tumors (40% vs. 16%). Although there was a trend of patients with MSI+ tumors towards a proximal gastric tumor location, early staging, and negative lymph node metastasis, there was no statistical significance compared to those with MSS tumors (P >.1). Comparison of overall and disease-free survival between gastric tumors that were MSI+ and those that were MSS found no statistically significant differences (P >.1). CONCLUSIONS: Microsatellite instability is a frequent event in gastric carcinogenesis and shows a trend towards distinct clinical and pathological characteristics of gastric cancer.
Adenocarcinoma↗
Isolated loss of PMS2 expression in colorectal cancers: frequency, patient age, and familial aggregation.
PURPOSE: Most colorectal cancers that have high levels of microsatellite instability (MSI-H) show loss of immunohistochemical expression of proteins that participate in the DNA mismatch repair process, most often involving MLH1 and MSH2. Less commonly, a third DNA mismatch repair protein, MSH6, may also be lost as the primary event. Rarely, tumors with MSI-H show normal expression of these three proteins. The genetic deficiency leading to the MSI-H phenotype in such cases is unknown. PMS2 is another member of the DNA mismatch repair complex. Its expression is generally lost in tumors with MLH1 loss of expression. Rarely, there is selective loss of PMS2 expression. We sought to describe the frequency and clinical correlates of selective loss of expression of PMS2 with the MSI-H tumor phenotype. EXPERIMENTAL DESIGN: Two thousand seven hundred nineteen colorectal cancers from both clinic- and research-based ascertainment were studied. Tumor MSI testing and immunohistochemistry for MLH1, MSH2, MSH6, and PMS2 were conducted. Medical records were abstracted for age at diagnosis, gender, colorectal cancer site, and family history. RESULTS: Five hundred thirty-five of the 2,719 tumors were MSI-H. Of these, 93% showed loss of expression of MLH1, MSH2, and/or MSH6. Thirty-eight showed normal expression for these proteins. PMS2 immunohistochemical staining was successful in 32 of 38 of these tumors. Of the 32, 23 showed selective loss of expression of PMS2. This was associated with young age of diagnosis and right-sided location but not with a striking family history of cancer. CONCLUSIONS: Overall, 97% of the MSI-H tumors showed loss of expression for one or more of these four mismatch repair proteins. Selective loss of expression of PMS2 was present in 72% of cases in which colorectal cancers had an MSI-H phenotype but no alteration of expression of MLH1, MSH2, and MSH6. The underlying mechanism involved cannot be determined from this study but could involve point mutations in other DNA mismatch repair genes with retention of immunohistochemical expression, somatic inactivation of PMS2, or germ line mutation of PMS2.
Adaptor Proteins, Signal Transducing↗
Microsatellite analysis in rheumatoid arthritis synovial fibroblasts.
OBJECTIVES: Rheumatoid arthritis (RA) is a chronic disease characterised by irreversible destruction of the affected joints. As aggressive transformed-appearing synovial fibroblasts are commonly found at the site of invasion of the rheumatoid synovium into the adjacent cartilage and bone, the presence of microsatellite instability (MSI) and expression of mismatch repair enzymes as a possible mechanism in the alteration of these cells was examined. METHODS: DNA was extracted from the synovial fibroblasts and blood of 20 patients with long term RA undergoing joint replacement, and the presence of MSI was studied at 10 microsatellite loci. In addition, immunohistochemistry was performed to evaluate the expression of the two major mismatch repair enzymes (hMLH1 and hMSH2) in rheumatoid synovium. RESULTS: MSI could not be detected in any of the fibroblast cell populations derived from the 20 different rheumatoid synovial samples. In addition, strong expression of mismatch repair enzymes could be seen in numerous cells, including fibroblasts, throughout the synovium. CONCLUSIONS: Applying the currently used and established markers for MSI, the data show for the first time that MSI does not appear to have an important role in alteration of rheumatoid synovial fibroblasts into an aggressive phenotype. On the other hand, strong mismatch repair enzyme synthesis in rheumatoid synovium supports the hypothesis of continuing DNA repair, presumably due to long term, inflammation induced DNA damage.
Adaptor Proteins, Signal Transducing↗
Increased risk for abnormalities on perioperative colon screening in patients with microsatellite instability-positive endometrial carcinoma.
Microsatellite instability (MSI) is a feature of certain hereditary and sporadic endometrial and colon cancers. We set out to determine whether molecular stratification of endometrial cancers based on tumor MSI status could help identify patients at increased risk for abnormalities found on perioperative colon screening. From a prospectively accrued series of 413 patients, medical records were reviewed from 94 patients with MSI positive (MSI+) and 94 patients with MSI negative (MSI-) endometrial cancers, matched by year of diagnosis. We reviewed clinicopathologic data and results of perioperative colon screening. Differences were analyzed using Fisher exact test and logistic regression analysis. There were no significant clinicopathologic differences between the two cohorts. Sixty-five percent of patients in each group underwent perioperative colon screening. However, patients with MSI+ cancers had a twofold increase in the frequency of colonic abnormalities (30% versus 14.8%, P = 0.044) over those with MSI- cancers. Furthermore, the only primary colon cancers (N = 2) were found in women with MSI+ endometrial cancers that were unmethylated at the MLH1 promoter. Our data suggest that patients with MSI+ endometrial cancers are at increased risk for abnormalities on perioperative colon screening. Those with MSI+MLH1 unmethylated cancers appear to be at highest risk.
Adaptor Proteins, Signal Transducing↗
Microsatellite instability and transitional cell carcinoma of the upper urinary tract.
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Aged↗
Analysis of microsatellite instability and X-inactivation in ovarian borderline tumors lacking numerical abnormalities by comparative genomic hybridization.
The genetic events underlying development of ovarian borderline tumors (tumors of low malignant potential) are not well understood. In our previous studies of microdissected samples from serous borderline tumors, comparative genomic hybridization (CGH) and/or fluorescence in situ hybridization (FISH) analyses showed that 3 of 13 tumors had detectable numerical abnormalities; the remaining 10 had none. In the present study, we examined microsatellite instability (MSI) and clonality in this same set of tumors. Although absence of chromosomal imbalances has been associated with the presence of MSI in some types of solid tumors, the extent of MSI in borderline tumors, and its role in their pathogenesis, is unclear. In our set of 13 tumors, no MSI was detected despite analysis with microsatellite markers recommended by the National Cancer Institute for assessment of MSI. Quantitative X-inactivation studies were informative at the androgen receptor gene AR in 9 of the 13 tumors and revealed that each of the 9 tumors was clonal. In two patients, bilateral tumors showed identical patterns of skewed X-inactivation. These studies confirm the clonality of borderline tumors and suggest that some borderline tumors may develop through mechanisms other than chromosomal imbalances or microsatellite instability.
Adult↗
Deletion of 1p loci and microsatellite instability in colorectal polyps.
Previous cytogenetic studies have indicated that a subset of large bowel adenomas have distal 1p deletions. We addressed this question by examining 70 sporadic polyps (63 adenomas, 5 hyperplastic polyps, and 2 polyps of undetermined histology) from 55 patients for alterations at eight loci on the short arm of chromosome 1 and found allelic imbalance (AI) or loss of one allele (LOH) in 14 (20%). The locus most frequently changed was MSI, which maps to 1p33-35. Fluorescence in situ hybridisation with centromeric and telomeric probes for chromosome 1, performed for 11 polyps, did not yield an abnormal number of signals, in accordance with the interpretation that the observed AI and LOH were the result of interstitial deletions in 1p. Whereas allelic imbalance at five other loci (mapping to 5q, 8p, 10p, 11p and 17q) was found less frequently, and then mainly in large (> 2 cm) tumours, the 1p alterations were equally distributed among small (< 1 cm) and large polyps. They were preferentially found in left-side tumours. Instability at microsatellite loci--the mutator phenotype--is demonstrated by shifts in the electrophoretic mobility of normal alleles. The mutator phenotype was first associated with hereditary nonpolyposis colorectal cancer but is also occasionally found in sporadic colorectal carcinomas; however, it is still uncertain when in the adenoma-carcinoma sequence in this type of genomic instability arises. We therefore looked for it at 12 dinucleotide repeat loci and found that seven tumours (six adenomas and one hyperplastic polyp) from seven patients had acquired new alleles not seen in the patients' corresponding normal DNA. Our results suggest that inactivation of a putative suppressor gene distally in chromosome arm 1p is an early event in colorectal tumourigenesis. They also show that microsatellite instability can be detected in large bowel polyps, indicating that this phenomenon, too, probably plays a pathogenic role for some colorectal tumours early in the adenoma-carcinoma sequence.
Adenoma↗
A molecular genetic and statistical approach for the diagnosis of dual-site cancers.
BACKGROUND: Concurrent tumors can be synchronous, independently derived, non-metastatic tumors or metastatic tumors. The prognosis and clinical management of patients with these different concurrent tumor types are different. METHODS: DNA from normal and tumor tissues of 62 patients with synchronous endometrial and ovarian, bilateral ovarian, or endometrial and bilateral ovarian tumors was analyzed for loss of heterozygosity and microsatellite instability using eight polymorphic microsatellite markers at loci frequently deleted in ovarian and/or endometrial cancers. A statistical algorithm was designed to assess the clonal relationship between the tumors. RESULTS: The original histopathology reports classified 26 (42%) case patients with single primary tumors and related metastatic lesions and 21 (34%) with independent primary tumors; 15 (24%) were unclassified. Genetic data identified 35 (56%) case patients with single primary tumors and related metastatic lesions, 18 (29%) with independent primary tumors, and nine (15%) that could not be typed. Excluding case patients with histopathology reports for which a clonal relationship was uncertain or was not reported, there was 53% concordance between genetic and histopathology diagnoses. Increasing the stringency of the statistical analysis increased the number of uncertain diagnoses but did not affect the proportion of discordant genetic and histologic diagnoses. CONCLUSIONS: We have developed a rapid and robust combined genetic and statistical method to establish whether multiple tumors from the same patient represent distinct primary tumors or whether they are clonally related and therefore metastatic. For the majority of case patients, histopathology reports and genetic analyses were in agreement and diagnostic confidence was improved. Importantly, in approximately one-fourth of all case patients, genetic and histopathologic analyses suggested alternative diagnoses. The results suggest that genetic analysis has implications for clinical management and can be performed rapidly as a diagnostic test with paraffin-embedded tissues.
Biomarkers, Tumor↗
Allelic imbalance at the DNA mismatch repair loci, hMSH2, hMLH1, hPMS1, hPMS2 and hMSH3, in squamous cell carcinoma of the head and neck.
BACKGROUND: Squamous cell carcinoma of the head and neck (SCCHN) is one of the 10 most frequently occurring cancers in the world. Defective mismatch repair, as exhibited by the phenomenon of microsatellite instability, has been observed in SCCHN although no reports of mismatch repair gene mutations or altered protein expression have been published. In a variety of microsatellite instability (MSI) positive cancers where mutations in the mismatch repair (MMR) genes were not observed, allelic imbalance at the loci of the MMR genes was prevalent. OBJECTIVE: To investigate whether allelic imbalance at the MMR genetic loci contributes to the development of SCCHN. MATERIALS AND METHODS: 35 matched normal/tumour SCCHN pairs were studied using 29 microsatellite markers located within and adjacent to six known DNA mismatch repair genes. In addition, mutational analysis and protein expression of hMSH2 and hMLH1 were investigated. RESULTS AND CONCLUSIONS: We demonstrated that 36 and 17% of the analysed SCCHN specimens exhibited allele imbalance at the hMLH1 and hMSH3 genetic loci, respectively. Allelic instability at these two loci was found to be correlated with the MSI status of the SCCHN tumours. Allelic instability was found to be uncommon at the other MMR gene loci analysed. One mutation was found in hMSH2 and none in hMLH1 in this series of tumours. 23 of 24 (96%) of the examined SCCHN tumours showed reduced expression of either hMSH2 or hMCH1 genes. Allelic instability in the MMR genes, hMLH1 and hMSH3, is proposed to be involved in the aetiology of SCCHN tumours.
Adaptor Proteins, Signal Transducing↗
Accumulated frameshift mutations at coding nucleotide repeats during the progression of gastric carcinoma with microsatellite instability.
Microsatellite instability (MSI) and frameshift mutations in genes containing nucleotide repeats have been reported in a subset of gastric carcinomas, but the mutational profiles in precancerous lesions have not been characterized. To characterize the genetic events during gastric carcinogenesis, we analyzed DNA from 56 gastric adenomas and 167 gastric carcinomas for MSI using five microsatellite markers and for frameshift mutations at coding nucleotide repeats of the type II transforming growth factor beta receptor, BAX, hMSH3, hMSH6, IGF II receptor, and E2F-4 genes. On the basis of the number of markers displaying instability per tumor, the tumors were divided into three groups: those with two or more of the five markers showing instability (high MSI [MSI-H]), those with one of the five markers showing instability (low MSI [MSI-L]), and those with no instability. MSI-H was found in 8 adenomas (14%) and 19 carcinomas (11%), and MSI-L was found in 8 adenomas (14%) and 9 carcinomas (5%). These groups were tested for correlations with several clinicopathologic parameters. MSI-H gastric adenomas were related to the high histologic grade of composing dysplastic glands (p = 0.004), and MSI-H gastric carcinomas were associated with exophytic tumor growth (p = 0.005). We found 48 frameshift mutations at coding nucleotide repeats of the six genes, and all mutations except one were found in MSI-H gastric tumors. Only one of the 17 MSI-L tumors showed frameshift mutations at coding nucleotide repeats of the transforming growth factor beta receptor II gene. Compared with MSI-H gastric carcinomas, MSI-H adenomas had no mutations in the hMSH6 and the IGF II receptor genes, less frequent mutations in the transforming growth factor beta receptor II (38% versus 63%), BAX (13% versus 37%), and hMSH3 (13% versus 37%) genes, and more frequent mutations in the E2F-4 (50% versus 37%) gene. Our findings suggest that MSI and E2F-4 mutations are early genetic events and that mutations of the other five genes are accumulated during the progression of gastric carcinomas with MSI.
Adenoma↗
Genetic instability in lung cancer: concurrent analysis of chromosomal, mini- and microsatellite instability and loss of heterozygosity.
To investigate what kind of genetic instability plays important roles in lung carcinogenesis, we analyzed micro- and minisatellite instability, loss of heterozygosity (LOH) and chromosome instability in 55 cases of lung cancer, including, 10 squamous cell, 5 large cell, and 3 small cell carcinomas, and 37 adenocarcinomas. Analysis of minisatellite instability, the mechanism of which is different from microsatellite instability, has not been reported previously. Minisatellite instability was detected in only one case (1/55, 1.8%), and the frequency of microsatellite instability was low, being found only in three cases (3/55, 5.5%). In contrast, LOH, for at least in one locus, was observed in 27 cases (49.1%). In adenocarcinomas, the frequency of LOH was higher in poorly differentiated compared to more differentiated carcinomas. For chromosome instability, a similar correlation between differentiation grade and instability was observed in adenocarcinomas. And instability was more common in large cell and small cell carcinomas than in adenocarcinomas. Our analysis showed that chromosome instability and LOH, rather than mini- and microsatellite instability, play significant roles in the development of lung cancer.
Adenocarcinoma↗
Genotypic and phenotypic progression in endometrial tumorigenesis: determining when defects in DNA mismatch repair and KRAS2 occur.
We set out to determine the relative timing of loss of DNA mismatch repair and KRAS2 mutation in endometrial tumorigenesis. We studied endometrial carcinoma (CA) and synchronous atypical endometrial hyperplasia (AEH), the premalignant precursor of endometrial cancer. Carcinoma and hyperplasia were investigated for loss of mismatch repair as evidenced by microsatellite instability (MSI) and for KRAS2 mutations. Endometrial cancers previously shown to be MSI-positive were evaluated for KRAS2 codon 12 and 13 mutations. DNA was isolated from foci of AEH concomitant with, but physically remote from, the cancers by use of tissues prepared by laser capture microdissection (LCM). The AEH DNAs were then assessed for MSI and KRAS2 mutations. Of 210 endometrial CAs investigated, 51 (26%) were MSI-positive, and among those, 21 (41%) arose concomitantly with AEH. Of 41 foci of AEH (mean, two foci per patient) investigated, 34 (83%) were MSI-positive. KRAS2 mutations were seen in 5/51 (10%) MSI-positive carcinomas. From the five patients informative for both KRAS2 mutation and MSI, 10 foci of AEH were available for investigation. All 10 AEH specimens (100%) were MSI-positive, and six (60%) had the KRAS2 mutation present in the coexisting CA. The observation that some MSI-positive AEH specimens lack the KRAS2 mutation seen in the coexisting CA supports a model in which loss of DNA mismatch repair precedes KRAS2 mutation. However, in addition to the absence of KRAS2 mutations in AEH, we discovered mutations in LCM hyperplasia and carcinoma specimens that were not present in the portion of the cancers originally investigated. These discordant genotypes suggest genetic heterogeneity in endometrial hyperplasia and concomitant cancer.
Base Pair Mismatch↗
Marked differences in the frequency of microsatellite instability in gastric cancer from different countries.
OBJECTIVE: Previous studies have reported variable rates of microsatellite instability (MSI) in gastric cancer. We investigated the frequency of MSI in invasive gastric carcinoma of patients from three geographic regions. METHODS: Genomic DNA from gastric cancer and nontumor tissue from 22 Korean, 20 Colombian, and 26 U.S. patients was amplified with five microsatellite markers. RESULTS: MSI was more frequently seen in gastric cancer from Korea, affecting 50% of patients, in contrast with gastric cancers from the U.S. (7%) and Colombia (15%) (p = 0.003 and p = 0.03, respectively). MSI at one locus was significantly more frequent in gastric cancer from individuals >65 yr (p = 0.01). MSI was similarly associated with both diffuse and intestinal types of gastric cancer. CONCLUSIONS: MSI affects the two major histological types of gastric cancer, and was more frequent in gastric cancer from Korea than in the other countries, suggesting that the relative importance of different pathways of gastric carcinogenesis may vary in diverse regions of the world.
Aged↗
TP53 mutation and microsatellite instability status for the prediction of survival in adjuvant-treated colon cancer patients.
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Antimetabolites, Antineoplastic↗
Microsatellite instability: marker of a mutator phenotype in cancer.
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Biomarkers↗
Correspondence re: C.R. Boland et al., A National Cancer Institute workshop on microsatellite instability for cancer detection and familial predisposition: development of international criteria for the determination of microsatellite instability in colorectal cancer. Cancer Res., 58: 5248-5257, 1998.
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Chromosome Aberrations↗
[The role of the immunohistochemistry for hMLH1 and hMSH2 with detection of microsatellite instability to identify the kindreds with hereditary nonpolyposis colorectal cancer].
OBJECTIVE: To investigate the specificity and sensitivity of the immunohistochemistry for hMLH1 and hMSH2 with detection of microsatellite instability (MSI) to identify the kindreds with hereditary nonpolyposis colorectal cancer and to analyse its value in clinical practice. METHOD: Specimens of 16 cases with HNPCC and 16 cases with sporadic colorectal cancer were detected by immunostaining with hMLH1 and hMSH2 and MSI was also detected. RESULTS: The specificity and sensitivity of the immunohistochemistry for hMLH1 and hMSH2 were 91.7% and 87.5% respectively. The specificity and sensitivity of MSI were 100% and 75.0%. By combining two methods, the specificity and sensitivity were 91.7% and 93.8% respectively. CONCLUSIONS: By combination of the immunohistochemistry for hMLH1 and hMSH2 and detection of MSI to identify the kindreds with HNPCC, the specificity and sensitivity are improved which is better than to use either of them alone. And it is very easy and cheap that it can be used in clinics.
Adaptor Proteins, Signal Transducing↗