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Garth R Anderson

Publications and source records attributed to Garth R Anderson.

16 recordsLinked to original sources
PubMed2007

aCGH local copy number aberrations associated with overall copy number genomic instability in colorectal cancer: coordinate involvement of the regions including BCR and ABL.

In order to identify small regions of the genome whose specific copy number alteration is associated with high genomic instability in the form of overall genome-wide copy number aberrations, we have analyzed array-based comparative genomic hybridization (aCGH) data from 33 sporadic colorectal carcinomas. Copy number changes of a small number of specific regions were significantly correlated with elevated overall amplifications and deletions scattered throughout the entire genome. One significant region at 9q34 includes the c-ABL gene. Another region spanning 22q11-q13 includes the breakpoint cluster region (BCR) of the Philadelphia chromosome. Coordinate 22q11-q13 alterations were observed in 9 of 11 tumors with the 9q34 alteration. Additional regions on 1q and 14q were associated with overall genome-wide copy number changes, while copy number aberrations on chromosome 7p, 7q, and 13q21.1-q31.3 were found associated with this instability only in tumors from patients with a smoking history. Our analysis demonstrates there are a small number of regions of the genome where gain or loss is commonly associated with a tumor's overall level of copy number aberrations. Our finding BCR and ABL located within two of the instability-associated regions, and the involvement of these two regions occurring coordinately, suggests a system akin to the BCR-ABL translocation of CML may be involved in genomic instability in about one-third of human colorectal carcinomas.

Adult↗
PubMed2006

Genomic profiles of colorectal cancers differ based on patient smoking status.

Human sporadic colorectal cancer is the result of a lengthy somatic evolutionary process facilitated by various forms of genomic instability. Such instability arises endogenously from mutations in genes whose role is to preserve genomic integrity, and exogenously from environmental agents that generate genomic damage. We have found that cigarette smoking shifts the genomic profiles and genomic instability patterns of colorectal carcinomas. The genomic profiles of 57 consecutive cancers were examined; 31 cases were current or former smokers and 26 were nonsmokers. Genome-wide allelotypes of 348 markers were examined, along with comparative genomic hybridization (CGH) on ordered BAC microarrays, microsatellite instability, and inter-(simple sequence repeat) polymerase chain reaction instability. Tumors from nonsmokers exhibited losses of heterozygosity, particularly on chromosomes 14 and 18, whereas tumors from smokers exhibited a more diffuse pattern of allelic losses. Tumors from smokers exhibited higher overall rates of loss of heterozygosity, but showed lower rates of background microsatellite instability (MSI-L). On BAC array CGH, higher levels of generalized amplifications and deletions were observed in tumors from smokers, differentially affecting male smokers. In the transforming growth factor-beta signaling pathway, MADH4 mutations were more common in tumors from smokers, whereas transforming growth factor-beta RII mutations were more common among nonsmokers.

Adult↗
PubMed2006

Genomic instability of human aberrant crypt foci measured by inter-(simple sequence repeat) PCR and array-CGH.

Aberrant crypt foci (ACF) are the earliest identifiable neoplastic lesions in the colon. Thirty-two ACFs were examined for genomic instability in forms detectable either by inter-(simple sequence repeat) PCR or by array comparative genomic hybridization [array-CGH]. One-fourth of ACFs revealed moderate instability by inter-(simple sequence repeat) PCR; none showed amplifications or deletions on array-CGH. The absence of genomic events detectible by BAC array-CGH indicates early events in colorectal tumor progression are typically smaller than the approximate 150 kb size of a BAC clone insert.

Aged, 80 and over↗
PubMed2006

Genomic instability in invasive breast carcinoma measured by inter-Simple Sequence Repeat PCR.

We have measured genomic instability in invasive breast carcinomas and assessed the relationship of genomic instability to known tumor prognostic factors. DNAs from tumors and adjacent normal tissue of 18 breast cancer patients were subjected to inter-Simple Sequence Repeat (inter-SSR) PCR for quantitation of tumor genomic instability. Associations between genomic instability level and known breast cancer prognostic factors were evaluated using the Pearson Product Moment Correlation, the Kruskal-Wallis test of independent samples and the Mann-Whitney non-parametric test. Genomic instability was detected by inter-SSR PCR in over 90% of the breast tumors. The mean instability index was 3.08% (0-7.59%), approximately the same mean value observed in studies of colorectal and thyroid carcinomas. Significantly higher levels of instability were associated with tumors exhibiting necrosis. Genomic instability as measured is detected in the majority of breast cancers at levels comparable to other tumor types. Hypoxia, such as that observed in necrotic regions of tumors, has been associated with elevated genomic damage. We hypothesize that the higher levels of genomic instability detected in necrotic tumors is a consequence of hypoxia-associated DNA damage.

Adult↗
PubMed2005

Molecular prognosticators and genomic instability in papillary thyroid cancer.

OBJECTIVES/HYPOTHESIS: Tumor progression has been attributed to the accumulation of DNA damage concurrent with selection of advantageous mutations; this DNA damage may result from failure to maintain genomic integrity or from susceptibility to carcinogens. Glutathione S-transferases (GSTs), enzymes that metabolize many carcinogens, may play a role in preserving genome integrity. The objectives of this study are to assess the relationship of GST genotypes with prognosis, clinicopathologic parameters, and genomic instability in papillary thyroid cancer. STUDY DESIGN: Prospective analysis. METHODS: GSTM1 and GSTT1 genotypes of 35 matched normal and papillary thyroid cancer specimens were determined by polymerase chain reaction (PCR) using primers specific for the coding sequences of each gene. Genomic instability was measured by intersimple sequence repeat PCR for each tumor/normal pair and compared with the GAMES prognostic scoring system and clinicopathologic parameters including age, extrathyroidal extension, tumor grade, size, stage metastasis, sex, and smoking history. RESULTS: GSTM1 and GSTT1 null genotypes were found in the normal tissues of 46% and 45%, respectively. No gene losses were detected in the tumor specimens. A significant association between the GSTM1 null genotype and increased risk of recurrence and death was observed. Elevated GII correlated with smoking and tumor stage but not with GST genotype. CONCLUSION: The association of GSTM1 null genotype with intermediate and high risk GAMES categories suggests that GSTM1 provides some protection against disease progression. However, this protection does not confer resistance to disease onset. GST genotyping may be a useful adjunct prognosticator with GAMES.

Adolescent↗
PubMed2004

Genomic heterogeneity and instability in colorectal cancer: spectral karyotyping, glutathione transferase-Ml and ras.

Genomic instability in cancer is frequently described as being either chromosomal instability or microsatellite instability, although when events within chromosomes are monitored, extensive intrachromosomal instability is also found. Spectral karyotyping was used to visualize how extensively genomic instability gives rise to intratumor genomic heterogeneity in sporadic colorectal carcinomas. Two factors were then examined which might relate to intrachromosomal instability in colorectal cancers: the presence of the glutathione transferase-Ml gene to detoxify potential carcinogens, and the presence of activated ras which has been associated with chromosomal instability when first expressed. Intrachromosomal genomic instability was previously determined by inter-(simple sequence repeat) PCR (inter-SSR PCR) and by fractional allelic loss rate for 348 markers. GSTM1 status was determined for each of 49 tumors through use of specific PCR, and 28 of the tumors showed the GSTM1 null genotype. A significant association was found between GSTMl-null status and elevated inter-(simple sequence repeat) PCR instability. In contrast, no association was found with fractional allelic loss rate. The first exons of the K-ras and H-ras oncogenes were sequenced in 72 colorectal cancers; 19 of the tumors had a mutation in codon 12 of the K-ras gene (24.5%), but no H-ras mutations were found. A weak correlation (p=0.10) was observed between mutant K-ras and inter-(simple sequence repeat) PCR genomic instability, and no association existed with fractional allelic loss rate.

Colorectal Neoplasms↗
PubMed2004

The role of genomic instability in the pathogenesis of squamous cell carcinoma of the head and neck.

Measurements of genomic instability, or identification of genes responsible for instability, may potentially be used as molecular markers to predict disease course and response to therapy. Other possible applications include use of genomic instability measurements, or genes, as tools to screen for primary or recurrent disease. Methodologies for detection of genetic mutations in saliva, blood, and sputum have already been described[61,62]. Brennan et al [63] have described a molecular technique for analyzing histopathologically negative margins and lymph nodes for the presence of p53 gene mutation. This study showed that a positive molecular margin significantly predicted disease recurrence. The recognition that HNSCC is a genetically heterogeneous disease represents a major step toward developing an understanding of its underlying genetic basis. To develop an insight into this genetically heterogeneous disease, investigators must not only focus their efforts on specific head and neck disease sites. Laser-capture microdissection represents a powerful tool for isolating very specific cell populations from tumors [64]. Leethanakul et al[65] performed laser-capture microdissection on oral cavity SCC to construct stage-specific cDNA libraries. Sequencing of 96 clones from each of the six libraries constructed suggested the existence of 132 novel genes, which may play a role in the pathogenesis of HNSCC. The current literature suggests that many individuals diagnosed withHNSCC are genetically predisposed to developing malignancy because of some inherent deficiency of their capacity to maintain their genome in the presence of environmental stressors. Head and neck cancers are highly heterogeneous tumors and exhibit a wide variety of forms of genomic instability. Thus, genomic instability may be viewed as a fundamental force driving head and neck tumorigenesis and evolution. Future study of the specific genetic mechanisms that underlie genomic instability in the HNSCCpatient population is needed. It is only through study of this fundamental force that drives the development of these tumors that clinicians may gain the insight required to develop new diagnostic and therapeutic modalities to benefit the HNSCC patient population as a whole.

Carcinoma, Squamous Cell↗
PubMed2003

Anaplastic thyroid cancer evolved from papillary carcinoma: demonstration of anaplastic transformation by means of the inter-simple sequence repeat polymerase chain reaction.

BACKGROUND: In thyroid tumors, the coexistence of well- and poorly differentiated tumor types has led to the hypothesis that poorly differentiated thyroid tumors develop from well-differentiated thyroid tumors. By evaluating the genomic instability of histologically distinct but coexisting tumor foci, this study aimed to develop an improved understanding of thyroid tumorigenesis and tumor evolution. DESIGN: Laser capture microdissection (LCM) was carried out on archival formalin-fixed, paraffin-embedded sections from a tumor containing foci of classic papillary thyroid cancer and anaplastic thyroid cancer. DNA was extracted from each microdissected tumor focus. In addition, cryopreserved bulk normal and neoplastic thyroid tissue underwent DNA extraction. All DNA samples were subsequently evaluated for genomic instability by means of inter-simple sequence repeat polymerase chain reaction. RESULTS: The LCM DNA from each archival paraffin-embedded tumor focus demonstrated unique patterns of banding as compared with the cryopreserved tumor and normal tissue DNA. Thus, intratumoral variability in genomic instability was observed. Comparison of inter-simple sequence repeat polymerase chain reaction patterns of LCM DNA from adjacent foci of papillary and anaplastic tumors showed conserved genome alterations. CONCLUSIONS: At the genome level, thyroid tumors may be highly heterogeneous. The intratumoral histologic heterogeneity observed in thyroid neoplasms reflects genetically heterogeneous underlying tumor cell populations that are demonstrated by the observed differences in their rates and extents of genomic instability. The conserved genomic alterations in the microdissected papillary and anaplastic foci suggest intratumoral evolution, with transformation of a preexisting papillary tumor to anaplastic carcinoma.

Aged↗
PubMed2003

Anaplastic transformation of thyroid cancer: review of clinical, pathologic, and molecular evidence provides new insights into disease biology and future therapy.

BACKGROUND: Anaplastic thyroid cancer ranks among the most lethal of all human malignancies. Its rarity and rapidly fatal course have made it a difficult cancer to both study and treat. Unfortunately, there has been little progress in the management and control of this malignancy. Anaplastic transformation, or the intratumoral evolution of anaplastic carcinoma from pre-existing differentiated thyroid cancer, has become a well-accepted process, despite a limited understanding of its underlying mechanisms. METHODS: It is through review of the literature that an understanding of the aggressive disease biology can be developed. The aim of this review is to evaluate the relevant clinical, pathologic, and molecular studies to develop an insight into the mechanisms that underlie the intratumoral molecular evolution of anaplastic thyroid carcinoma. RESULTS/CONCLUSION: It is based on an understanding of this process that effective treatments for this aggressive malignancy are currently being developed.

Carcinoma↗
PubMed2003

Papillary thyroid cancer: high inter-(simple sequence repeat) genomic instability in a typically indolent cancer.

OBJECTIVES: The object of this study is to measure genomic instability in papillary thyroid cancer and correlate these measurements with known clinical prognosticators such as patient age, tumor size, histologic subtype, and three commonly used thyroid risk assessment indices. A secondary objective of this study was to use the measurements of genomic instability to estimate the number of mutational events present in the papillary thyroid cancer genome. METHODS: Inter-simple sequence repeat polymerase chain reaction (ISSR-PCR) is a rapid and reproducible technique for quantitation of genomic instability, or the degree of genome alteration, in solid tumors. This includes quantitation of amplifications, deletions, translocations, and insertions. Twenty-eight papillary carcinomas were evaluated by ISSR-PCR. RESULTS: Evaluation of 28 papillary carcinomas by ISSR-PCR demonstrated a wide range of genomic instability. Of the panel of clinicopathologic factors examined, only patient age was significantly associated with genomic instability. The mean genomic instability index value was greatest in the youngest age group, which was significantly different from the median value measured in the oldest age group (3.7, 2.5, respectively, p =.05). The mean value in the intermediate age group fell between the younger and older groups (3.1). By use of ISSR-PCR, we have calculated 15,000 individual genomic events as having occurred in each papillary tumor cell. CONCLUSIONS: Despite its generally indolent biologic behavior, papillary thyroid cancer exhibits a high degree of genomic instability comparable to that seen in colorectal cancer. These results suggest that elevated genomic instability, as measured by ISSR-PCR, may not be sufficient to enable thyroid tumor progression to less indolent disease and that this process is severely constrained by some additional essential factor such as the differentiated state of the tissue or the need to bring into play an additional form of genomic destabilization.

Adolescent↗
PubMed2003

Squamous cell carcinoma of the head and neck in nonsmokers and nondrinkers: an analysis of clinicopathologic characteristics and treatment outcomes.

BACKGROUND: The objective of this study was to describe the clinicopathologic manifestations of disease and outcomes of treatment among individuals without a history of smoking tobacco or consuming alcohol who develop head and neck cancer. METHODS: Of 1648 invasive head and neck cancer cases treated between 1970 and 2001 at Roswell Park Cancer Institute, 40 patients were identified as never having smoked tobacco or consumed alcohol during their lifetime. These cases were reviewed to gather data on multiple clinicopathologic variables. RESULTS: Mean age at presentation of nonsmoker/nondrinker head and neck cancer patients was 60 years (range, 27 to 90 years), and 78% (n = 31) of the patients were women. The distributions of tumor sites were 75.0% oral cavity (n = 30), 20.0% oropharynx (n = 8), and 5.0% larynx (n = 2). Sixteen patients (40%) experienced a recurrence of disease during the follow-up period, and 10 patients (25.0%) developed a second primary tumor a median of 6 years after their initial diagnosis. CONCLUSIONS: The nonsmoker/nondrinker head and neck cancer patient tends to be elderly and female, have oral cavity primary tumors, and be predisposed to second primary tumor development.

Adult↗
PubMed2002

Genomic instability measurement in the diagnosis of thyroid neoplasms.

BACKGROUND: Clinically palpable thyroid nodules are present in approximately 10% of the population, although only 5% to 7% of these nodules harbor malignancy. Fine-needle aspiration has become one of the central tools in the diagnostic armamentarium of the surgeon/endocrinologist. There is, however, up to a 30% indeterminate diagnostic rate associated with this technique, resulting in unnecessary surgical interventions for patients harboring benign disease. A second issue of clinical importance is the unreliability of predicting outcomes based either on histologic findings alone or in combination with clinical staging. To address these diagnostic and clinical shortcomings, we have used measurement of genomic instability as a diagnostic and prognostic indicator for thyroid neoplasms. METHODS: Genomic instability of thyroid tissue samples was determined by inter-(simple sequence repeat) PCR, microsatellite instability analysis, and fluorescence in situ hybridization (FISH) on thyroid neoplasms from 22 patients. RESULTS: Inter-(simple sequence repeat) PCR detected genomic instability with an index range 0% to 1.9% (mean, 0.56%) in patients with benign disease, whereas in patients with malignant histologic findings the values ranged from 0% to 6.6% (mean, 2.9%). This difference between benign and malignant values was statistically significant (p =.004). There was no demonstrable microsatellite instability or loss of heterozygosity for six markers examined in this group. Losses of chromosomes 17 and X in benign disease and gains of chromosomes 7, 12, 17, and X in Hurthle cell carcinoma were observed, although not at a significant rate. CONCLUSIONS: Genomic instability as measured by inter-(simple sequence repeat) PCR was significantly higher for malignant diseases compared with benign thyroid tissues, but no such association was seen with aneuploidy or microsatellite instability.

Adolescent↗
PubMedDate not supplied

Tissue eosinophilic infiltration: a useful marker for assessing stromal invasion, survival and locoregional recurrence in head and neck squamous neoplasia.

UNLABELLED: The assessment of stromal invasion in aerodigestive neoplastic squamous proliferation often poses diagnostic and therapeutic challenges. Eosinophilic infiltration is thought to be an adjunctive histologic criterion in determining tumor aggressiveness and invasion. We investigated whether an eosinophilic infiltration in head and neck squamous cell carcinoma measured in biopsies would aid in predicting tumor invasion, response to treatment, locoregional recurrence, and survival. METHODS: Eighty-seven patients with in situ and invasive squamous cell carcinoma of the head and neck region were evaluated and treated according to their staging. The number of eosinophils per high-power field (eosinophil/HPF), and per 10 high-power fields (eosinophil/10 HPF) at the tumor interface and in tumor tissue, was counted and classified as focally or diffusely present. Each sample was assigned an eosinophilic index of 1-4 based on the number of eosinophils/HPF or 10 HPF. Of 87 patients, 20 patients were followed up after appropriate treatment for locoregional recurrence, distant metastasis, and disease-free survival. RESULTS: Eosinophilic counts were elevated focally and/or diffusely more frequently in invasive squamous cell carcinoma than in noninvasive tumors. The increased eosinophilic counts, specifically > 10/HPF and > 20/10 HPF, were both significantly associated with stromal invasion. Greater than 10 eosinophils/HPF and/or > 20 eosinophils/10 HPF had the highest predictive power for invasion, with sensitivity, specificity, and positive predictive values of 66%, 94%, 96% and 61%, 100%, and 100%, respectively. Eosinophilic counts greater than 20 eosinophils/10 HPF and eosinophilic indices > 2 were virtually diagnostic for tumor invasion. Patients' biopsies with eosinophilic indices < 2 had a better survival (P = 0.0156). Using Cox regression analysis, we found that most patients' biopsies that had eosinophilic indices > 2 recurred locally or regionally. CONCLUSIONS: The elevated eosinophilic counts in biopsies and eosinophilic indices in specimens of squamous cell carcinoma of the aerodigestive tract are a histopathologic marker associated with tumor invasion and a clinical predictor for aggressive tumor biology. Similarly, the presence of eosinophils meeting these thresholds in an excisional specimen should indicate the need for additional therapeutic measures and close surveillance to detect earlier locoregional recurrence and possible distant metastasis.

Adult↗
PubMedDate not supplied

Aberrant crypt foci.

Colon cancer evolves through epithelial cell deregulation and inappropriate proliferation. These histopathological characteristics are exemplified in the biochemical, immunohistochemical, genetic and epigenetic elements detected within colonic mucosa. Early detection is paramount for the prevention of colon cancer deaths. Aberrant crypt foci (ACF) are thought to be the earliest identifiable neoplastic lesions in the colon carcinogenetic model. The progression of ACF to polyp and, subsequently, to cancer parallels the accumulation of several biochemical alterations and mutations whereby a small fraction of ACF evolve to colon cancer. Recent data indicate that, not uncommonly, some ACF bypass the polyp stage in their carcinogenesis thus reinforcing the importance of their early detection and our understanding of their pathogenesis. Since ACF were first detected in carcinogen-treated mice, research efforts have focused on these microscopically visible lesions both in animal and human models. ACF show variable histological features, characterized by Kudo (20) and, therefore, can be grouped into differing categories by in vivo examination with high-magnification-chromoscopic-colonoscopy (HMCC). As expected, ACF are more frequently detected in distal animal and human colons coinciding with the geographic distribution of colorectal cancer (CRC). Various proteomic (Prot) markers may be altered within ACF suggesting possible prospective pathological changes. These markers include Calreticulin, Transgelin, Serotransferrin, Triphosphate isomerase and Carbonic anhydrase II. Other markers of importance include carcinoembryonic antigen (CEA), B-catenin, placental cadherin (P-cadherin), epithelial cadherin (E-cadherin), inducible nitric oxide synthase (iNOS), cyclooxygenase (COX-2) and P16INK4a. Genetic mutations of K-ras, B-Raf APC and p53 have been demonstrated in ACF as well as the epigenetic alterations of CpG island methylation. Genomic instabilities (GI), illustrated by a higher GI Index (GII), microsatellite instability (MSI), loss of heterozygosity (LOH) and defects in mismatch repair (MMR) systems, are also expressed. These transformations may lead to the identification of the earliest pathological features initiating colon tumorigenesis. In this review, the advances in ACF research as precursors of CRCs are highlighted.

Animals↗