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Biomedical subjects

Robert Stoehr

Publications and source records attributed to Robert Stoehr.

At least 19 recordsLinked to original sources
PubMed2007

Role of the STK15 Phe31Ile polymorphism in renal cell carcinoma.

The search of inherited cancer susceptibility factors is an important subject in cancer epidemiology. Analyses of single nucleotide polymorphisms (SNP) in various genes revealed a correlation between the presence of specific allelic variants and cancer predisposition in diverse malignancies. STK15 is an important protein in control of the integrity of the mitotic spindle apparatus and genomic stability. We analysed the distribution of the functionally important T91A SNP in the STK15 gene in a cohort of renal cell carcinoma (RCC) patients and compared it to the distribution in a control group without malignancies. DNA from formalin-fixed, paraffin-embedded healthy renal tissue (RCC patients) or peripheral blood samples (control group) was isolated according to standard protocols. Allelic variant of STK15 nucleotide 91 was determined using restriction fragment length polymorphism (RFLP) analysis. Overall, 156 RCC patients and 158 patients without any malignancy were analysed. The distribution of the STK15 SNP in RCC patients (T/T, 58.97%; A/T, 36.53%; A/A, 4.49%) did not significantly differ from that of the control group (T/T, 51.27%; A/T, 41.14%; A/A, 7.59%). There was also no correlation between genotype and tumour grade or stage or other histopathological characteristics of the tumours. This first analysis of the STK15 T91A SNP in RCC patients revealed no correlation between a certain allelic variant and an increased risk for RCC.

Aurora Kinase A↗
PubMed2006

Chromosome 9 deletions are more frequent than FGFR3 mutations in flat urothelial hyperplasias of the bladder.

Flat urothelial hyperplasias (FUHs) in patients with papillary bladder tumours frequently show deletions of chromosome 9, suggesting that FUH could be the first neoplastic step in the development of papillary bladder cancer. FGFR3 mutations are frequent in non-invasive papillary tumours with low risk of progression. Our aim was to investigate the frequency of FGFR3 mutations and deletions of chromosomes 9p/q and 8p/q in FUH. Thirty FUH and 9 simultaneous or consecutive tumours were detected by 5-ALA-based photodynamic cystoscopy. DNA was isolated from frozen sections and whole genome amplification was done by I-PEP-PCR, followed by LOH analysis on chromosomes 8p/q and 9p/q. FGFR3 mutations were detected by SNaPshot analysis. LOH analysis on FUH revealed deletions at 9p/q (11/30, 37%) and 8p/q (3/30, 10%). FGFR3 mutations were found in 7/30 FUH (23%). Only 2 FUH showed an FGFR3 mutation without deletions of chromosome 9. In contrast, 6 FUH revealed chromosome 9 deletions but wild type FGFR3 (p = 0.03). These results suggest that chromosome 9 deletions are the earliest genetic alterations in bladder cancer. The detection of FGFR3 mutations in FUH further supports the role of this lesion as precursor of papillary bladder cancer.

Adult↗
PubMed2006

Cell cycle phase distribution analysis in chronic lymphocytic leukaemia: a significant number of cells reside in early G1-phase.

BACKGROUND AND AIMS: Chronic lymphocytic leukaemia (CLL) is a frequent non-Hodgkin lymphoma characterised by a heterogeneous clinical course. Assessment of cell cycle phase kinetics might be important for prediction of clinical behaviour and prognosis. METHODS: Distribution of neoplastic cells in CLL within the cell cycle was evaluated by determining the labelling indices (LI, i.e. percentage of positive cells) of markers specific for late G1-phase (cyclin E), S-phase (cyclin A), and G2/M-phase (cyclin B1), and Mcm2, a novel marker of proliferative potential, in a large cohort of patients (n = 79) using tissue microarray (TMA) technology. Utilising a combination of these markers, an algorithm was developed--subtracting the combined LIs of cyclin E, cyclin A and cyclin B1 from the LI of Mcm2--to determine the percentage of tumour cells residing in early G1-phase, which is probably a critical state for the malignant potential of CLL. RESULTS: 27.11% of cells had acquired proliferative potential as indicated by expression of Mcm2. Only a small number of cells were found to be in late G1-phase (7.16%), S-phase (3.31%) or G2/M-phase (0.98%), while 15.66% of cells were considered to be in early G1-phase. CONCLUSION: Cell cycle phase distribution can easily be assessed by immunohistochemistry in routinely processed paraffin-embedded specimens. A large number of neoplastic cells in CLL have proliferative potential, with a significant sub-population residing in early G1-phase. Estimates of these cells may identify cases likely to exhibit a more aggressive biological behaviour and adverse clinical course.

Adult↗
PubMed2006

Elevated microsatellite alterations at selected tetranucleotides (EMAST) and mismatch repair gene expression in prostate cancer.

Elevated microsatellite alterations at selected tetranucleotides (EMAST), a new form of microsatellite instability (MSI) affecting tetranucleotide repeats, was recently described to be frequent in several tumor types (e.g., bladder, lung, ovarian, and skin cancers). EMAST was found as a form of microsatellite alteration distinct from the MSI phenotype in hereditary nonpolyposis colorectal cancer (HNPCC)-related tumors which mostly affects mono- and dinucleotide repeats. To date, no study has investigated the role of EMAST in prostate cancer. We therefore analyzed 81 prostate tumors using 10 markers frequently detecting EMAST in other cancer types and the National Cancer Institute-consensus panel for HNPCC detection plus BAT40. In addition, we investigated p53 gene alterations [loss of heterozygosity (LOH)] and the expression of p53 and the mismatch repair (MMR) genes hMLH1 and hMSH2 on tissue microarrays. EMAST was detected in 4/81 (5%) cases and MSI in 6/79 (7.6%) cases. LOH of p53 was found in 9/45 (20%) informative cases. There was no correlation between MSI status and the histopathological or molecular characteristics of the tumors. Immunohistochemistry revealed p53 positivity in 5/61 (8%) tumors. There was a significant correlation between tumors showing a recurrence within 3 years after treatment and p53 positivity (p=0.029). Reduced hMLH1 expression, but no complete loss, was detected in 9/41 (22%) tumors without any correlations to histopathological or clinical features. Analysis of hMSH2 expression was available from 58/81 (72%) tumors. Staining intensity was as follows: negative in 7/58 (12%), weak staining in 16/58 (27.5%) samples, moderate staining in 19/58 (33%) samples, and strong staining in 16/58 (27.5%) samples. When negative/weak staining and moderate/strong staining were considered as two groups, there was a significant association between hMSH2 expression and tumor recurrence (p=0.039). In conclusion, our data show that MSI and EMAST are infrequent but distinct patterns of MSI in prostate tumors not related to MMR defects, p53 alterations, and histopathological characteristics. p53 positivity and moderate to strong hMSH2 expression of prostate tumors are correlated with early disease recurrence and indicate an unfavorable clinical course of the disease. These two genes could be useful biomarkers for the prediction of patients' outcome and should be analyzed in prospective studies.

Adaptor Proteins, Signal Transducing↗
PubMed2006

High frequency of FGFR3 mutations in adenoid seborrheic keratoses.

FGFR3 germline mutations cause autosomal dominant skeletal disorders including achondroplasia, thanatophoric dysplasia, severe achondroplasia with developmental delay and acanthosis nigricans, and Crouzon syndrome. Somatic mutations of FGFR3 have been identified in bladder cancer, multiple myeloma, and other neoplasms. FGFR3 mutations have also been detected in 40% of seborrheic keratoses (SKs) of the hyperkeratotic and acanthotic subtype, which are very common benign skin tumors. Using a multiplex SNaPshot assay that covers 11 activating FGFR3 mutations, we investigated a series of 27 SKs of the adenoid subtype. Mutations were detected in 23 of 27 (85%) adenoid SKs. R248C mutations were the most frequent mutation type. In two SKs, the A393E mutation was found, which has not been described in acanthotic and hyperkeratotic SKs so far. Three adenoid SKs displayed two simultaneous FGFR3 mutations. Adenoid SKs seem to be characterized by a higher frequency of FGFR3 mutations than hyperkeratotic and acanthotic SKs. The mechanism for the high rate of somatic FGFR3 mutations in these benign skin tumors remains elusive, but UV light exposure may play a potential role, especially in the R248C mutations.

Aged↗
PubMed2006

Elevated microsatellite instability at selected tetranucleotide repeats does not correlate with clinicopathologic features of bladder cancer.

INTRODUCTION: The aim of the present study was to evaluate whether elevated microsatellite instability (MSI) at selected tetranucleotide repeats (EMAST) is associated with clinicopathologic and molecular parameters in urinary bladder cancer (BC). METHODS: A consecutive series of 117 nonselected urothelial BCs was studied. Microsatellite analysis and detection of loss of heterozygosity (LOH) was performed after microdissection by using 12 markers selected for sensitive detection of EMAST. Furthermore, five markers (BAT25, BAT26, D2S123, APC, and D17S250) of the Bethesda consensus panel for detection of colorectal cancer within the hereditary non-polyposis colon cancer syndrome (HNPCC) were analyzed. Expression of TP53 and mismatch repair (MMR) proteins hMSH2, hMLH1, and hMSH6 was investigated by immunohistochemistry. RESULTS: EMAST was detected in 10 of 117 patients (8.5%), whereas MSI in the HNPCC panel was found in one of 114 cases (0.9%). LOH in EMAST markers was seen in six of 114 (5.3%) cases. All tumours showed normal expression of hMSH2 and hMLH1. Overexpression of TP53 was observed in nine of 117 evaluated cases (7.7%). No association of EMAST and TP53 expression could be demonstrated. None of the clinicopathologic or molecular parameters were associated with EMAST. CONCLUSIONS: EMAST is another distinct form of MSI in urothelial BC. However, EMAST seems to be a rare event in non-selected urothelial BC and does not seem to be associated with commonly used clinicopathologic and clinical features in patients with BC.

Humans↗
PubMed2006

Mitogen-activated protein kinase signaling is activated in prostate tumors but not mediated by B-RAF mutations.

OBJECTIVES: A dysregulated mitogen-activated protein kinase (MAPK) pathway plays an important role in various malignancies and is often mediated by mutations in several oncogenes (eg, RAF, RAS). B-RAF mutations, predominantly the specific V600E mutation and additional alterations in exons 11 and 15, were frequently detected in malignant melanomas, papillary thyroid tumors, and colorectal cancers with microsatellite instability (MSI). The present study investigated B-RAF mutations, MSI status, and activation of MAPK signaling in prostate tumors. METHODS: The V600E mutation of the B-RAF gene was analyzed using allele-specific polymerase chain reaction in 79 archival prostatic adenocarcinomas (pT1aG1 to pT3cG3, median Gleason score 6); exons 11 and 15 were sequenced. MSI status was determined using the National Cancer Institute consensus panel for hereditary nonpolyposis colorectal carcinoma (HNPCC) detection. Active MAPK signaling was investigated using immunohistochemistry for p44/ERK1 and p42/ERK2. RESULTS: No B-RAF mutations could be detected. Six of 79 tumors showed MSI positivity. Active MAPK signaling was detected in 51% of the analyzed tumors. No correlation was found between MAPK activity and histopathologic/clinical characteristics. CONCLUSION: The most frequent B-RAF gene alterations are not involved in prostate carcinogenesis. MSI is infrequent in prostate cancer and is not linked to B-RAF mutations. MAPK signaling is frequently activated in prostate tumors and might be suitable for a therapeutic approach.

Aged↗
PubMed2006

Multifocal urothelial cancers with the mutator phenotype are of monoclonal origin and require panurothelial treatment for tumor clearance.

PURPOSE: UC is a disease of the entire urothelium, characterized by multiplicity and multifocality. The clonal relationship among multiple UCs has implications regarding adjuvant chemotherapy. It has been investigated in studies of chromosomal alteration and single gene mutation. However, these genetic changes can occur in unrelated tumors under similar carcinogenic selection pressures. Tumors with high MSI have numerous DNA mutations, of which many provide no selection benefit. While these tumors represent an ideal model for studying UC clonality, their low frequency has prevented their previous investigation. MATERIALS AND METHODS: We investigated 32 upper and lower urinary tract UCs with high MSI and 4 nonUC primary cancers in 9 patients. We used the high frequency and specificity of individual DNA mutations in these tumors (MSI at 17 loci) and the early timing of epigenetic events (methylation of 7 gene promoters) to investigate tumor clonality. RESULTS: Molecular alterations varied among tumors from different primary organs but they appeared related in the UCs of all 9 patients. While 7 patients had a high degree of concordance among UCs, in 2 the UCs shared only a few similar alterations. Genetic and epigenetic abnormalities were frequently found in normal urothelial samples. CONCLUSIONS: Multiple UCs in each patient appeared to arise from a single clone. The molecular order of tumor development varied from the timing of clinical presentation and suggested that residual malignant cells persist in the urinary tract despite apparent curative surgery. These cells lead to subsequent tumor relapse and new methods are required to detect and eradicate them.

Adult↗
PubMed2006

Mosaicism of activating FGFR3 mutations in human skin causes epidermal nevi.

Epidermal nevi are common congenital skin lesions with an incidence of 1 in 1,000 people; however, their genetic basis remains elusive. Germline mutations of the FGF receptor 3 (FGFR3) cause autosomal dominant skeletal disorders such as achondroplasia and thanatophoric dysplasia, which can be associated with acanthosis nigricans of the skin. Acanthosis nigricans and common epidermal nevi of the nonorganoid, nonepidermolytic type share some clinical and histological features. We used a SNaPshot multiplex assay to screen 39 epidermal nevi of this type of 33 patients for 11 activating FGFR3 point mutations. In addition, exon 19 of FGFR3 was directly sequenced. We identified activating FGFR3 mutations, almost exclusively at codon 248 (R248C), in 11 of 33 (33%) patients with nonorganoid, nonepidermolytic epidermal nevi. In 4 of these cases, samples from adjacent histologically normal skin could be analyzed, and FGFR3 mutations were found to be absent. Our results suggest that a large proportion of epidermal nevi are caused by a mosaicism of activating FGFR3 mutations in the human epidermis, secondary to a postzygotic mutation in early embryonic development. The R248C mutation appears to be a hot spot for FGFR3 mutations in epidermal nevi.

Adolescent↗
PubMed2005

Expression of minichromosome maintenance protein 2 as a marker for proliferation and prognosis in diffuse large B-cell lymphoma: a tissue microarray and clinico-pathological analysis.

BACKGROUND: Minichromosome maintenance (MCM) proteins are essential for the initiation of DNA replication and have been found to be relevant markers for prognosis in a variety of tumours. The aim of this study was to assess the proliferative activity of diffuse large B-cell lymphoma (DLBCL) in tissue microarray (TMA) using one of the minichromosome maintenance proteins (Mcm2) and to explore its potential value to predict prognosis. METHODS: Immunohistochemistry for Mcm2 was performed on TMAs constructed from 302 cases of DLBCL. A monoclonal mouse antibody was used after heat induced antigen retrieval. Mcm2 expression was scored quantitatively. Positivity for Mcm2 was defined as presence of nuclear expression of Mcm2 in greater than or equal to 40 % of tumour cells. A statistical analysis was carried out of the association of Mcm2 and the clinico-pathological characteristics. RESULTS: Mcm2 expression was clearly evident in the nuclei of proliferating non-neoplastic cells and tumour cells. Positivity for Mcm2 was found in 46% (98/211) of analysable cases. A significant correlation existed between Mcm2 expression and presence of bulky disease (p = 0.003). Poor disease specific survival was observed in patients with DLBCL positive for Mcm2 expression in the univariate analysis (p = 0.0424). CONCLUSION: Mcm2 expression can be used to assess tumour proliferation and may be useful as an additional prognostic marker to refine the prediction of outcome in DLBCL.

Biomarkers, Tumor↗
PubMed2005

Improved clonality analysis of multifocal bladder tumors by combination of histopathologic organ mapping, loss of heterozygosity, fluorescence in situ hybridization, and p53 analyses.

The clonality status of multifocal bladder tumors is still controversially discussed with experimental evidence for both monoclonality and field cancerization. Methodologically, loss of heterozygosity (LOH) and genomic sequencing analyses are widely used in clonality analysis of malignant tumors. In the present study, we used LOH analysis and genomic sequencing in combination with fluorescence in situ hybridization (FISH) and extensive histopathologic whole-organ mapping to determine the clonal relationship of multifocal bladder cancer disease. Tissue sections (1 cm(2)) covering the entire urothelial lining were systematically dissected from 2 cystectomy specimens (cystectomy 1, no urothelial lesions, bladder infiltration by a leiomyosarcoma of the vaginal wall; cystectomy 2, multifocal pT3G3 tumors). The location of each sample was documented (bladder mapping). Urothelial cells were microdissected for LOH (chromosomes 9, 17p) and FISH analysis (CDKI2 (9p21), FACC (9q22), p53 (17p13.1), and centromeric probes for corresponding chromosome). Exons 5 to 9 of the p53 gene were sequenced in all tumor samples. No chromosomal alterations were detected in the cystectomy specimen without urothelial malignancies. The tumor-bearing bladder showed an increasing frequency of deletions with increasing malignancy of the investigated lesions. LOH analysis detected deletions only on chromosomes 9p and 17p. In contrast, FISH analysis revealed deletions of all investigated genes at chromosomes 9p, 9q, and 17p in all samples analyzed (preneoplastic and neoplastic tissue). An identical p53 mutation in codon 281 was found in all 7 analyzable tumor samples. Combination of molecular data with histopathologic bladder mapping suggested a monoclonal development of the multifocal lesions mostly via intraurothelial migration. Our data strengthen the results from recently published studies that patients with advanced urothelial carcinoma seem to have a monoclonal panurothelial disease in most cases. FISH showed a much higher sensitivity for detection of chromosomal losses than classical LOH analysis, especially in preneoplastic and small lesions. Combining 3 molecular approaches together with histopathologic organ mapping presents a valuable tool to determine the clonality status of multifocal bladder tumors.

Chromosomes, Human, Pair 17↗
PubMed2005

Gene expression profiling of progressive papillary noninvasive carcinomas of the urinary bladder.

PURPOSE: The aim of the present study was to define gene expression profiles of noninvasive and invasive bladder cancer, to identify potential therapeutic or screening targets in bladder cancer, and to define genetic changes relevant for tumor progression of recurrent papillary bladder cancer (pTa). EXPERIMENTAL DESIGN: Overall, 67 bladder neoplasms (46 pTa, 3 pTis, 10 pT1, and 8 pT2) and eight normal bladder specimens were investigated by a combination of laser microdissection and gene expression profiling. Eight of 16 patients with recurrent noninvasive papillary bladder tumors developed carcinoma in situ (pTis) or invasive bladder cancer (> or = pT1G2) in the course of time. RNA expression results of the putative progression marker cathepsin E (CTSE) were confirmed by immunohistochemistry using high-throughput tissue microarray analysis (n = 776). Univariate analysis of factors regarding overall survival, progression-free survival, and recurrence-free survival in patients with urothelial bladder cancer was done. RESULTS: Hierarchical cluster analyses revealed no differences between pTaG1 and pTaG2 tumors. However, distinct groups of invasive cancers with different gene expression profiles in papillary and solid tumors were found. Progression-associated gene profiles could be defined (e.g., FABP4 and CTSE) and were already present in the preceding noninvasive papillary tumors. CTSE expression (P = 0.003) and a high Ki-67 labeling index of at least 5% (P = 0.01) were the only factors that correlated significantly with progression-free survival of pTa tumors in our gene expression approach. CONCLUSIONS: Gene expression profiling revealed novel genes with potential clinical utility to select patients that are more likely to develop aggressive disease.

Aged↗
PubMed2005

Deletions of chromosomes 9 and 8p in histologically normal urothelium of patients with bladder cancer.

OBJECTIVES: Multifocality and frequent recurrence of urothelial carcinoma of the urinary bladder indicate a disease of the entire "urothelial field", but little is known about chromosomal alterations in histologically normal urothelium. Histopathologically normal urothelium from patients with and without concurrent urothelial carcinoma was analyzed for loss of heterozygosity (LOH) on chromosomes 8p, 9 and 17p, regions that are known to play an important role in urothelial carcinogenesis. MATERIALS AND METHODS: Histologically inconspicuous urothelial mucosa samples (n = 160) from cystectomy specimens of patients with urothelial carcinoma (n = 15, max. diagnosis: CIS, pT1-4; all tumors grade 3) were studied. Control samples (n = 50) were obtained from patients with benign prostatic hyperplasia (n = 30) and from cystectomies performed for invasive non-urothelial carcinoma (n = 20). Tissue samples were laser-microdissected and DNA was isolated using standard protocols. LOH analyses were performed using 16 polymorphic markers on chromosomes 8p, 9p/q and 17p. RESULTS: All investigated samples were informative for at least one microsatellite marker on each chromosome/chromosomal arm. Deletions were found on chromosome 9 and/or 8p in 15/160 (9.4%) of normal urothelial samples from urothelial cancer patients. These alterations were only found in 5/15 patients with urothelial carcinoma. There were no deletions on chromosome 17p. The marker D9S1113 on chromosome 9q33-34 was most frequently affected (11/15 samples, 73%). No chromosomal deletions were found in any of the 50 urothelial control samples. CONCLUSION: Specific genetic alterations frequently associated with bladder cancer are detectable in histologically normal urothelium of patients with bladder cancer, supporting the field effect hypothesis in urothelial carcinogenesis. However, intramucosal spread of tumor cells that escape light microscopic detection remains a possibility, since normal urothelium and concurrent carcinomas showed matching deletions. Chromosomal deletions in normal bladder mucosa are not a common finding and argue against a frequent genomic alteration of the entire urothelial field in bladder carcinogenesis.

Aged↗
PubMed2005

RNA expression profiling of normal and tumor cells following photodynamic therapy with 5-aminolevulinic acid-induced protoporphyrin IX in vitro.

Photodynamic therapy using 5-aminolevulinic acid-induced protoporphyrin IX synthesis as a photosensitizing reagent is an encouraging modality for cancer treatment. Understanding the mechanism of tumor phototoxicity is important to provide a basis for combinatory therapy regimens. A normal cell line (UROtsa, urothelial) and two tumor cell lines (RT4, urothelial; HT29, colonic) were treated with cell line-specific LD50 doses of light after exposure to 5-aminolevulinic acid (100 microg/mL), and harvested for RNA extraction 0, 10, and 30 minutes after irradiation. The RNA was hybridized to the metg001A Affymetrix GeneChip containing 2,800 genes, focusing on cancer-related and growth regulatory targets. Comparing the gene expression profiles between the different samples, 40 genes (e.g., SOD2, LUC7A, CASP8, and DUSP1) were identified as significantly altered in comparison with the control samples, and grouped according to their gene ontology. We selected caspase-8 (CASP8) and dual specificity phosphatase 1 (DUSP1) for further validation of the array findings, and compared their expression with the expression of the immediate early gene FOS by quantitative reverse transcription-PCR. RNA expression of CASP8 stayed unchanged whereas DUSP1 RNA was up-regulated in normal and tumor cells starting 30 minutes after irradiation. In contrast, FOS RNA was found continuously up-regulated over time in all three cell lines. Induction of DUSP1 protein expression was clearly shown after 1 hour using Western blot analysis. Interestingly, no changes of caspase-8 protein expression but activation of catalytic activity was detected only in UROtsa cells starting 1 hour after photodynamic therapy, whereas no changes were seen in both tumor cell lines. According to caspase-8, the active caspase 3 fragment was found only in the normal urothelial cell line (UROtsa) 1 hour after photodynamic therapy. Combined data analysis suggests that photodynamic therapy in vitro (LD50) leads to apoptosis in UROtsa and to necrosis in the tumor cell lines, respectively. RNA expression profiling of normal and tumor cell lines following photodynamic therapy with 5-aminolevulinic acid gave insight into the major molecular mechanisms induced by photodynamic therapy.

Aminolevulinic Acid↗
PubMed2005

Microdissection for detecting genetic aberrations in early and advanced human urinary bladder cancer.

Laser microdissection is an essential method for the investigation of the multistep carcinogenic process in the urinary bladder. Reliable detection of tumor-specific alterations which can be compromised by the presence of normal cells, requires microdissection of pure tumor cell populations (>80%) to detect loss of heterozygosity (LOH) by either fluorescence in situ hybridization (FISH) or sequence analysis. Multiple molecular methods need to be performed in the course of studying often-small lesions. This chapter describes in detail the use of laser microdissection, whole-genome amplification by improved primer extension preamplification (I-PEP)-polymerase chain reaction, and subsequent LOH, FISH, and sequencing analysis in the investigation of urothelial tumors and their precursor lesions. The combination of the described methods allows a wide spectrum of molecular investigations of tumor cells and helps to understand the fundamental alterations involved in urothelial carcinogenesis.

Chromosome Aberrations↗
PubMed2005

Laser microdissection for microsatellite analysis in colon and breast cancer.

Microsatellite analysis is a frequently used method for detection of chromosomal deletions by loss of heterozygosity studies and for detection of microsatellite instability. For reliable microsatellite analyses, a tumor cell content of at least 80% is required. Therefore, laser microdissection is an important prerequisite for those studies, allowing the contamination-free isolation of morphologically defined pure tumor cell populations. The combination of exact microdissection and subsequent whole-genome amplification by improved primer extension preamplification polymerase chain reaction (I-PEP-PCR) facilitates the analysis of multiple microsatellite loci in small tumor samples. This is especially important for the investigation of malignant tumors with low tumor cellularity. This chapter describes in detail the use of whole genome amplification by I-PEP PCR and microsatellite analysis in laser microdissected specimens of colon and breast cancer.

Breast Neoplasms↗