PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “DNA MICROSATELLITE INSTABILITY”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 919 records · Page 51Linked to original sources
PubMed2003

Alterations in p53 predict response to preoperative high dose chemotherapy in patients with gastric cancer.

AIMS: To evaluate the usefulness of molecular markers in predicting histopathological and clinical response to preoperative high dose chemotherapy (HDCT) and survival of patients with advanced gastric cancer. METHODS: In a phase II trial, 25 patients with metastatic gastric cancer received preoperative tandem HDCT consisting of etoposide, cisplatin, and mitomycin, followed by autologous bone marrow transplantation to achieve surgical resectability. Samples before and after treatment, from normal and tumour tissue, were characterised histopathologically, and both p53 and BAX expression was analysed by immunohistochemistry. Pretreatment formalin fixed, paraffin wax embedded samples from normal and tumour tissue were microdissected, and the extracted DNA was preamplified using improved primer extension preamplification polymerase chain reaction. Detection of microsatellite instability (MSI) or loss of heterozygosity (LOH) was performed using markers for p53, BAX, BAT25, BAT26, D2S123, D17S250, and APC. Exons 5-9 of the p53 gene were sequenced directly on ABI 373. RESULTS: Four parameters were significantly associated with response to chemotherapy and prolonged overall survival: positive p53 immunostaining, positive p53 mutation status before chemotherapy, strong histological regression induced by preoperative HDCT, and surgical treatment. Patients's sex or age, tumour location or stage, lymph node status, Lauren classification, MSI, or LOH did not influence duration of survival significantly in this high risk population. CONCLUSION: Positive p53 immunostaining and p53 mutation status in pretreatment tumour biopsies might be useful molecular predictors of response and prognosis in patients with advanced gastric cancer treated by preoperative HDCT.

Adult↗
PubMed2006

A novel MSH2 germline mutation in homozygous state in two brothers with colorectal cancers diagnosed at the age of 11 and 12 years.

Hereditary non-polyposis colorectal cancer (HNPCC) syndrome is caused by heterozygous germline mutations in DNA mismatch repair genes (MMR), (MSH2, MLH1, MSH6, and PMS2) and it is inherited in an autosomal dominant pattern with high penetrance. Several patients have been reported carrying bi-allelic MMR gene mutations and whose phenotype resembled a syndrome with childhood malignancies including hematological malignancies, brain, and colorectal tumors. This phenotype is similar to the tumor spectrum of MMR knockout mice. Herein we describe two brothers of healthy consanguineous parents from Pakistan, who had developed two and three colorectal cancers at the ages of 11 and 12 years, respectively, and less than 30 polyps. Tumor specimens were microsatellite instable (MSI-H), and expression of MSH2 and MSH6 was lost. Mutation analyses of DNA samples from both patients revealed a novel homozygous c.2006-5T > A mutation in intron 12 of the MSH2 gene. This phenotype of the brothers is unusual as they neither develop hematological malignancies nor brain tumors at an older age of presentation than other patients with homozygous MSH2 mutations. The milder phenotype may be due to the expression of low amounts of MSH2 protein with reduced activity.

Child↗
PubMed2001

Genetic heterogeneity and alterations in chromosome 9 loci in a localized region of a functional pituitary adenoma.

The molecular alterations reported in pituitary adenomas include mutations at the G(s)alpha in somatotrophinomas, and hypermethylation of the p16 tumor suppressor gene. There are, however, no reports of genomic instability or intratumor genetic heterogeneity in pituitary adenomas. We have studied the microsatellite loci on the short arm of chromosome 9 (9p) and the DNA fingerprinting pattern, of adjacent compartments, about 2 mm across, in a functional chromophobe pituitary adenoma secreting growth hormone and prolactin. The microsatellite loci were studied by PCR amplification using locus specific primers, while the DNA fingerprinting pattern was studied by randomly amplified polymorphic DNA (RAPD) analysis. Normal leukocyte DNA was taken as control. Only one compartment (Ta) showed alterations in several of the microsatellite loci and in the RAPD pattern vis a vis corresponding normal DNA and also the other two compartments of the tumor. This provides evidence for the localized nature of genomic instability in this tumor.

Adenoma↗
PubMed2000

Microsatellite instability in gastrointestinal tract tumours.

Although a number of studies have documented microsatellite instability (MSI) in gastrointestinal tumours, the clinical significance is uncertain. In this study the MSI status and clinicopathological features were examined in gastric and colorectal tumours. Eighty-four gastrointestinal tumours were examined for MSI. Normal and tumour DNA isolated from the same patients were analysed at five different microsatellite loci. Clinical features of these patients were also collated and compared with MSI status. High level MSI (MSI-H) (as defined by instability in 2 or more microsatellites) was detected in 6 out of 47 (13%) colon tumours and 6 of 37 (16%) gastric tumours. The frequency of MSI-H between these groups was not statistically significant (P = 0.36). There was no significant correlation with patient age or gender, UICC stage, or degree of differentiation of the tumour. This was true both when analysed as a group, as well as when divided into colon and gastric sites. Our results confirm that a proportion of sporadic tumours from the colon and stomach exhibit an MSI-H phenotype. However, there was no significant relationship between the presence of MSI and any of the clinicopathological characteristics studied.

Colonic Neoplasms↗
PubMedDate not supplied

Analysis of MSH3 in endometrial cancers with defective DNA mismatch repair.

OBJECTIVE: To clarify the origin of defective mismatch repair (MMR) in sporadic endometrial cancers with microsatellite instability (MSI), a thorough mutation analysis was performed on the human mismatch repair gene MSH3. METHODS: Twenty-eight MSI-positive endometrial cancers were investigated for mutations in the human mismatch repair gene MSH3 using single-strand conformation variant (SSCV) analysis of all 24 exons. All variants were sequenced. Loss of heterozygosity was investigated at all MSH3 polymorphisms discovered. A subset of tumors were investigated for methylation of the 5' promoter region of MSH3 using Southern blot hybridization. RESULTS: An identical single-base deletion (delta A) predicted to result in a truncated proteins was discovered in six tumors (21.4%). This deletion occurs in a string of eight consecutive adenosine residues (A8). Because simple repeat sequences are unstable in cells with defective MMR, the observed mutation may be an effect, rather than a cause, of MSI. Evidence of inactivation of the second MSH3 allele in tumors with the delta A mutation would strongly support a causal role for these MSH3 mutations. However, there was no evidence of a second mutation, loss of sequences, or methylation of the promoter region in any of the tumors with the delta A mutation. CONCLUSION: Although the delta A mutation is a frequent event in sporadic MSI-positive endometrial cancers, it may not be causally associated with defective DNA MMR.

Blotting, Southern↗
PubMed2001

Decreased androgen-responsive growth of human prostate cancer is associated with increased genetic alterations.

Genetic mechanisms involved in prostate tumor progression from the androgen-responsive to androgen-unresponsive stage are not well understood because of the tremendous heterogeneity in the tumor as well as the lack of suitable models. Using 165 repeat microsatellite DNA markers distributed equally over all of the chromosomes, we determined an association between genetic alterations and androgen-unresponsive growth in three stages of LNCaP cell model (C33: early, androgen-responsive; C51: mid, decreased androgen-responsive; and C81: late, androgen-unresponsive and increased tumorigenicity). Furthermore, the genetic alterations were confirmed in laser microdissected normal and cancerous tissues from 15 clinical samples of human prostatic adenocarcinomas using selected markers. A stem-line karyotype analysis exhibited an identical chromosomal pattern in both C33 and C81 stage cells except for the structural rearrangements of chromosome 3 and a gain of one copy of the Y chromosome in the androgen-unresponsive C81 stage cells. Nine microsatellite DNA markers on seven different chromosomes (1, 4, 5, 11, 17, 18, and 19) showed microsatellite instability (MSI) in both C51 and C81 stage cells. Additionally, 23 markers on 15 different chromosomes revealed MSI in C81 cells. Chromosomal regions demonstrating allelic loss (AL) include 1q, 3p, 5p, 8q, 9q, and 13q in C51 and C81 cells. In clinical human specimens, MSI was observed on chromosomes 1 (20%), 5 (23%), 17 (40%), and 19 (36%), whereas ALs were found 40% on chromosomal region 1q, 20% on 3p, 26% on 5p and 8q, and 33% on 13q. In conclusion, the LNCaP cell model showed the increasing number of genetic changes including MSI and AL. These increased genetic alterations may be associated with the development of the androgen-unresponsive phenotype.

Androgens↗
PubMed1996

Detection of microsatellite instability in cancers by arbitrarily primed-PCR fingerprinting using a fluorescently labeled primer (FAP-PCR).

The microsatellite mutator phenotype (MMP), detected as a change in the number of repeating units in hundreds of thousands of microsatellite sequences in the tumor cell genome, underlies the carcinogenesis of a variety of tumors including sporadic and hereditary nonpolyposis colon cancers. This enhanced microsatellite instability was discovered using arbitrarily primed polymerase chain reaction (AP-PCR) fingerprinting of DNA from colon cancers. In this study, we found an arbitrary primer that can amplify multiple DNA fragments containing repeated sequences, including the poly A tracts found in the Alu repeats of the human genome. The combined use of primer labeling with fluorescence and an automated DNA sequencing analysis of AP-PCR products (FAP-PCR) detected alterations in fingerprint bands in all DNA samples previously determined to belong to the MMP. Fluorescent AP-PCR fingerprinting using this single arbitrary primer provides a convenient and efficient method for detecting tumor specific fingerprint alterations that are usually undetectable by conventional fingerprinting.

Blotting, Southern↗
PubMed2002

Frequent and multiple mutations at minisatellite loci in sporadic human colorectal and gastric cancers--possible mechanistic differences from microsatellite instability in cancer cells.

Minisatellites (MNs), composed of 5 to 100 nucleotide repeat units, range from 0.5 to 30 kb in length, and have been reported to be mutated in various human malignancies. In this study, frequencies of MN mutations in sporadic human colorectal (34 cases) and gastric cancers (24 cases) at various clinicopathological stages were assessed by multilocus DNA fingerprint analysis with three MN probes, Pc-1, 33.6 and 33.15. MN mutations were observed in both colorectal and gastric cancers, but at a significantly higher frequency in the former (56%) than in the latter (25%). Multiplicities of MN mutations were 1.50 +/- 1.81 and 0.46 +/- 1.10 in colorectal and gastric cancers, respectively, and the difference was also significant. Neither the presence nor multiplicity of MN mutations in either colorectal or gastric cancer cases had any correlation with the pathological stage, histological grading or the presence of microsatellite instability (MSI). Although the biological relevance of MN mutations still remains to be clarified, a subset of colorectal and gastric cancers could feature a new type of genomic instability, distinct from MSI.

Adult↗
PubMed1997

Mini- and microsatellites.

While the faithful transmission of genetic information requires a fidelity and stability of DNA that is involved in translation into proteins, it has become evident that a large part of noncoding DNA is organized in repeated sequences, which often exhibit a pronounced instability and dynamics. This applies both to longer repeated sequences, minisatellites (about 10-100 base pairs), and microsatellites (mostly 2-4 base pairs). Although these satellite DNAs are abundantly distributed in all kinds of organisms, no clear function has been discerned for them. However, extension of trinucleotide microsatellite sequences has been associated with several severe human disorders, such as Fragile X syndrome and Huntington's disease. Rare alleles of a minisatellite sequence have been reported to be associated with the ras oncogene leading to an increased risk for several human cancers. A dynamic behavior of repeated DNA sequences also applies to telomeres, constituting the ends of the chromosomes. Repeated DNA sequences protect the chromosome ends from losing coding sequences at cell divisions. The telomeres are maintained by the enzyme telomerase. Somatic cells, however, lose telomerase function and gradually die. Cancer cells have activated telomerase and therefore they acquire immortality.

DNA Fingerprinting↗
PubMed1999

Heterogeneity studies identify a subset of sporadic colorectal cancers without evidence for chromosomal or microsatellite instability.

Two apparently independent mechanisms of instability are recognized in colorectal cancer, microsatellite instability and chromosomal instability. Evidence from colorectal cancer cell lines indicates the presence of either, or both, types of instability in the vast majority. Here, we sought to determine the prevalence of such instability in primary sporadic colorectal cancers. Microsatellite instability was established by demonstration of ovel clonal, nongerm-line alleles in at least two of four tested loci. Chromosomal abnormalities were identified by comparative genomic hybridization (CGH) and flow cytometric analysis of nuclear DNA content. Tumours harbouring chromosomal instability were distinguished from those with stable but aneuploid karyotypes by comparing chromosomal defects at multiple sites throughout each cancer. This analysis allowed assessment of both the number of chromosomal abnormalities and their heterogeneity throughout the tumour. The results confirm that microsatellite instability is consistently associated with multiple, repeated changes in microsatellites throughout the growth of the affected colorectal carcinomas. There were also several carcinomas in which major structural or numerical abnormalities in chromosomes had clearly continued to arise during tumour growth. However, a substantial subset of tumours showed neither microsatellite instability nor multiple, major chromosomal abnormalities. We suggest that the development of a proportion of colorectal cancers proceeds via a different pathway of carcinogenesis not associated with either of the currently recognized forms of genomic instability.

Aged↗
PubMed2003

A microdissection and molecular genotyping assay to confirm the identity of tissue floaters in paraffin-embedded tissue blocks.

CONTEXT: A recurring problem in surgical pathology practice is specimen mix-up and floater contamination. While many cases can be resolved histologically, a significant number remain unclear and may have serious clinical and medicolegal implications. OBJECTIVES: To design a microdissection and genotyping assay to identify contaminating floater tissues in paraffin-embedded tissues that is optimized for small samples, and to use the assay to resolve a series of clinical cases with floater tissues. MATERIALS AND METHODS: Twenty-one cases of possible tissue floater contamination in paraffin-embedded tissue blocks were included. Using 4 unstained, 4-microm-thick histologic sections, multiple sites were microdissected under direct visualization either by hand or by laser capture microdissection. Nonneoplastic and neoplastic tissues were sampled. Polymerase chain reaction was performed for a panel of 10 polymorphic microsatellite markers at 1p34, 3p26, 5q21, 9p21, 10q23, and 17p13. Allele size and content were analyzed semiquantitatively by fluorescent capillary electrophoresis, and the genotypes for the tissues in the paraffin-embedded tissue blocks were compared for identity. RESULTS: Tissue identification was successful in all cases, despite small tissue sample size and fixation effects. Comparative analysis of neoplastic tissue floaters and the presumptive source tumor was performed when possible to control for possible allelic loss or microsatellite instability. CONCLUSIONS: Microdissection and genotyping are effective and reliable means to objectively resolve problems of possible floater contamination. Even minute tissue samples provide sufficient DNA template for polymerase chain reaction microsatellite analysis. Because of the potential clinical implications of floaters, we recommend that all suspected floaters that would change a diagnosis from benign to malignant be subjected to genotyping assay to confirm the identity of the floater tissue.

Biopsy↗
PubMedDate not supplied

Carcinogenesis in the remnant stomach following distal gastrectomy with billroth II reconstruction is associated with high-level microsatellite instability.

Although the gastric remnant has been reported to be at high risk for carcinogenesis, the process of carcinogenesis of gastric remnant cancer (GRC) remains unclear. In this study, genetic alterations in GRC were examined in order to investigate the carcinogenic pathways of GRC. Twenty-one patients with GRC were investigated and were compared to 36 patients with sporadic gastric cancer (GC) as a control group. Microsatellite instability (MSI) was examined using 8 primer marker sets. Immunohistochemical staining for hMLH1 and hMSH2 as the DNA mismatch repair system was performed. The high-level MSI (MSI-H) frequency (43%; 9/21) of GRC was significantly higher (p=0.001) than that of the sporadic GC (6%; 2/36). The MSI-H incidence (67%: 8/12) of GRC after gastrojejunostomy (Billroth II anastomosis) was significantly (p=0.015) higher than that (11%: 1/9) after gastroduodenostomy (Billroth I anastomosis). The MSI-H in GRC was significantly (p<0.0001) associated with lack of expression of both hMLH1 and hMSH2. The inactivation of hMLH1 or hMSH2 was significantly frequent (p=0.035) in GRC after gastrojejunostomy (58%: 7/12), compared with that in gastroduodenostomy (11%: 1/9). GRC was more closely associated with the MSI pathway than sporadic GC. Carcinogenesis in the remnant stomach following distal gastrectomy with gastrojejunostomy was found to be associated with the MSI pathway due to inactivation of the DNA mismatch repair system.

Adaptor Proteins, Signal Transducing↗
PubMed1998

The effects of static magnetic fields and X-rays on instability of microsatellite repetitive sequences.

To determine the genetic effect of static magnetic fields (SMF), which are not supposed to produce any significant DNA damage, we took advantage of DNA mismatch repair (MMR) deficient cells, in which all the errors produced during DNA replication are left uncorrected. We first established a simple and less labor-intensive method to analyze genetic changes in microsatellite repetitive sequences in the MMR-deficient cells. After exposure to a strong SMF (6.34T) for 24 h, both MMR deficient HCT116 cells and proficient HeLa S3 cells did not exhibit any significant effect on microsatellite changes. Moreover, when HCT116 cells were synchronized at the G1/S boundary by aphidicolin and exposed to SMF during the whole S-phase, no increase in microsatellite changes was either observed. In contrast, irradiation by a low dose X-ray (2Gy) significantly increased microsatellite changes in HCT116 cells. This suggested that exposure to strong SMF may not induce any significant level of genetic changes in microsatellite sequences.

Cell Line↗
PubMed2006

Microsatellite instability analysis in hereditary non-polyposis colon cancer using the Bethesda consensus panel of microsatellite markers in the absence of proband normal tissue.

BACKGROUND: Hereditary non-polyposis colon cancer (HNPCC) is an autosomal dominant syndrome predisposing to the early development of various cancers including those of colon, rectum, endometrium, ovarium, small bowel, stomach and urinary tract. HNPCC is caused by germline mutations in the DNA mismatch repair genes, mostly hMSH2 or hMLH1. In this study, we report the analysis for genetic counseling of three first-degree relatives (the mother and two sisters) of a male who died of colorectal adenocarcinoma at the age of 23. The family fulfilled strict Amsterdam-I criteria (AC-I) with the presence of extracolonic tumors in the extended pedigree. We overcame the difficulty of having a proband post-mortem non-tumor tissue sample for MSI testing by studying the alleles carried by his progenitors. METHODS: Tumor MSI testing is described as initial screening in both primary and metastasis tumor tissue blocks, using the reference panel of 5 microsatellite markers standardized by the National Cancer Institute (NCI) for the screening of HNPCC (BAT-25, BAT-26, D2S123, D5S346 and D17S250). Subsequent mutation analysis of the hMLH1 and hMSH2 genes was performed. RESULTS: Three of five microsatellite markers (BAT-25, BAT-26 and D5S346) presented different alleles in the proband's tumor as compared to those inherited from his parents. The tumor was classified as high frequency microsatellite instability (MSI-H). We identified in the HNPCC family a novel germline missense (c.1864C>A) mutation in exon 12 of hMSH2 gene, leading to a proline 622 to threonine (p.Pro622Thr) amino acid substitution. CONCLUSION: This approach allowed us to establish the tumor MSI status using the NCI recommended panel in the absence of proband's non-tumor tissue and before sequencing the obligate carrier. According to the Human Gene Mutation Database (HGMD) and the International Society for Gastrointestinal Hereditary Tumors (InSiGHT) Database this is the first report of this mutation.

Adult↗
PubMed2000

Associations between cigarette smoking, lifestyle factors, and microsatellite instability in colon tumors.

BACKGROUND: Microsatellite instability (MSI) has been reported to occur in approximately 10%-15% of colon tumors. MSI is characterized by the presence of mutations in tandemly repeated DNA sequences known as microsatellites. Some individuals with unstable tumors have inherited mutations in mismatch repair genes, but MSI is also observed in sporadic colon cancer. It is unknown whether lifestyle factors associated with colon cancer, such as physical activity, body size, cigarette smoking, or use of aspirin and/or nonsteroidal anti-inflammatory drugs, contribute to MSI in sporadic tumors. METHODS: Data from a population-based, case-control study of colon cancer were used. Case subjects were between 30 and 79 years of age at the time of diagnosis and included both men and women. Questionnaire data were used to obtain information on lifestyle factors. Tumor MSI was determined with the use of a panel of 10 tetranucleotide repeats and two mononucleotide repeats. A total of 1510 case subjects had valid questionnaire data and tumor DNA from which we were able to obtain MSI status. Questionnaire data were compared with lifestyle factors reported by 2410 population-based control subjects. All statistical tests were two-sided. RESULTS: MSI-positive (MSI(+)) tumors were most common in older people and women and in the proximal colon. Patients with MSI(+) tumors were more likely to smoke 20 or more cigarettes a day than case subjects with MSI-negative (MSI(-)) tumors (odds ratio for being a smoker = 1.6 [95% confidence interval = 1.0-2.5] for men and 2.2 [95% confidence interval = 1.4-3.5] for women). The association between MSI(+) tumors and cigarette smoking was strongest among case subjects who started to smoke at a young age, smoked for 35 or more years, and were either current smokers or had stopped fewer than 15 years before diagnosis. A statistically significant linear trend of increased risk of MSI(+) tumors was observed with increasing amount smoked (P<.01). CONCLUSIONS: This study suggests that smoking cigarettes statistically significantly contributes to MSI in colon tumors. We estimate that approximately 21% of MSI in colon tumors may be attributable to cigarette smoking.

Adult↗