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A F Gazdar

Publications and source records attributed to A F Gazdar.

At least 37 records · Page 2Linked to original sources
PubMed2001

5' CpG island methylation of the FHIT gene is correlated with loss of gene expression in lung and breast cancer.

Allele loss and loss of expression of fragile histidine triad (FHIT), a putative tumor suppressor gene located in chromosome region 3p14.2, are frequent in several types of cancers. Tumor-acquired methylation of promoter region CpG islands is one method for silencing tumor suppressor genes. We investigated 5' CpG island methylation of the FHIT gene in 107 primary non-small cell lung cancer (NSCLC) samples and corresponding nonmalignant lung tissues, 39 primary breast carcinomas, as well as in 49 lung and 22 breast cancer cell lines by a methylation-specific PCR assay. In addition, we analyzed brushes from the bronchial epithelium of 35 heavy smokers without cancer. FHIT methylation was detected in 37% of primary NSCLCs, 31% of primary breast cancers, and 65% of lung and 86% of breast cancer cell lines. The frequency of methylation in small cell and NSCLC cell lines were identical. Methylation was found in 9% of the corresponding nonmalignant lung tissues and in 17% of bronchial brushes from heavy cigarette smokers. FHIT methylation was significantly correlated with loss of FHIT mRNA expression by Northern blot analysis in lung cancer cell lines and with loss of Fhit expression in NSCLC and breast tumors by immunostaining. We conclude that methylation of FHIT is a frequent event in NSCLC and breast cancers and is an important mechanism for loss of expression of this gene. Methylation of FHIT commences during lung cancer pathogenesis and may represent a marker for risk assessment.

Acid Anhydride Hydrolases↗
PubMed2001

Genome-wide allelotyping analysis reveals multiple sites of allelic loss in gallbladder carcinoma.

Although gallbladder carcinoma (GBC) is a highly malignant neoplasm, there is very limited information about the molecular changes involved in its pathogenesis. To identify the chromosomal locations of putative tumor suppressor gene loci involved in the pathogenesis of GBC, we conducted a genome-wide allelotyping or loss of heterozygosity (LOH) analysis of GBCS: Microdissected tissue from 24 archival GBCs and their matched control DNAs were analyzed for PCR-based LOH using 169 microsatellite markers spanning all nonacrocentric autosomal arms and the X chromosome. The chromosomal arms with the greatest frequencies of LOH (> or = 60%) were 3p, 6q, 7q, 8p, 9p, 9q, 11q, 12q, 17p, 18q, 19p, 22q, and XQ: The average fractional allele loss index in GBC cases was high (0.43) and frequent breakpoints were detected in gallbladder tumors. Of interest, 21 different regions of frequent LOH (hot spots) defined as > or = 50% for individual GBC samples were detected in this neoplasm, nearly half of them confined to one microsatellite marker. We conclude that in GBC at least 21 chromosomal regions with frequent allele losses are involved, suggesting that several putative tumor suppressor genes are inactivated in its pathogenesis. Overall, these data provide global estimates of the extent of genetic changes leading to GBC and will be useful for the identification of new tumor suppressor genes and for multiple new markers for translational research.

Adenocarcinoma↗
PubMed2001

Expression of the RNA component of human telemorase (hTR) in ThinPrep preparations from bladder washings.

BACKGROUND: The enzyme telomerase is associated with cellular immortality and is expressed in the vast majority of human neoplasms. The expression of the RNA component of human telomerase (hTR) shows excellent concordance with enzyme activity. METHODS: In this study, hTR expression was analyzed in a series of 18 perioperative bladder washings and compared with histologic diagnoses from material obtained in the same setting. The hTR expression analysis used an 35S-based in-situ hybridization assay. ThinPrep preparations fixed in PreservCyt solution (Cytyc Corporation, Boxborough, MA) were hybridized with sense and antisense hTR probes. A 1-4+ grading scheme was used, with appropriate positive and negative controls. RESULTS: Five of six (83%) lesions with benign histology had hTR expression that was 2+ or less in the exfoliated urothelial cells. In contrast, 11 of 12 (93%) lesions with malignant histology had an hTR expression that was focally 3+ or more, with 7 of 12 (58%) lesions having 4+ hTR expression in at least some urothelial clusters. Although increased hTR expression was present in smears with malignant urothelial cells, a similar trend was not seen with muscularis propria invasion or higher grades of TCC on subsequent histology. CONCLUSIONS: The use of in situ hybridization technique bypasses the need for stringent specimen processing and allows identification of the specific cell type that expresses telomerase. Cancer (Cancer Cytopathol)

Carcinoma, Transitional Cell↗
PubMed2001

Searching for microsatellite mutations in coding regions in lung, breast, ovarian and colorectal cancers.

RepX represents a new informatics approach to probe the UniGene database for potentially polymorphic repeat sequences in the open reading frame (ORF) of genes, 56% of which were found to be actually polymorphic. We now have performed mutational analysis of 17 such sites in genes not found to be polymorphic (<0.03 frequency) in a large panel of human cancer genomic DNAs derived from 31 lung, 21 breast, seven ovarian, 21 (13 microsatellite instability (MSI)+ and eight MSI-) colorectal cancer cell lines. In the lung, breast and ovarian tumor DNAs we found no mutations (<0.03-0.04 rate of tumor associated open reading frame mutations) in these sequences. By contrast, 18 MSI+ colorectal cancers (13 cancer cell lines and five primary tumors) with mismatch repair defects exhibited six mutations in three of the 17 genes (SREBP-2, TAN-1, GR6) (P<0.000003 compared to all other cancers tested). We conclude that coding region microsatellite alterations are rare in lung, breast, ovarian carcinomas and MSI (-) colorectal cancers, but are relatively frequent in MSI (+) colorectal cancers with mismatch repair deficits.

Base Pair Mismatch↗
PubMed2001

Functional evidence for a telomerase repressor gene on human chromosome 10p15.1.

Based on the sites of frequent allelic loss in hepatocellular carcinoma, five normal human chromosomes (2, 4, 5, 10 and 16) were transferred individually into a telomerase-positive human hepatocellular carcinoma cell line, Li7HM, by microcell-mediated chromosome transfer (MMCT). Chromosome 10, but not the others, repressed telomerase activity immediately and stopped cell growth after 50 population doublings (PDs). Loss of the transferred 10p loci resulted in the emergence of revertant cells that continued to proliferate and expressed telomerase activity, suggesting the presence of a telomerase repressor gene on this chromosomal arm. Transfer of a series of defined fragments from chromosome 10p successfully narrowed down the responsible region: a 28.9-cM region on 10p15 (between WI-4752 and D10S249), but not a 26.2-cM region (between D10S1728 and D10S249), caused repression of telomerase activity and progressive telomere shortening. A strong correlation between the expression level of telomerase catalytic subunit gene (hTERT) and telomerase activity was observed. These findings suggest that a novel telomerase repressor gene which controls the expression of hTERT is located on the 2.7-cM region (between WI-4752 and D10S1728) on chromosome 10p15.1.

Carcinoma, Hepatocellular↗
PubMed2001

Aberrant promoter methylation of multiple genes in non-small cell lung cancers.

Aberrant methylation of CpG islands acquired in tumor cells in promoter regions is one method for loss of gene function. We determined the frequency of aberrant promoter methylation (referred to as methylation) of the genes retinoic acid receptor beta-2 (RARbeta), tissue inhibitor of metalloproteinase 3 (TIMP-3), p16INK4a, O6-methylguanine-DNA-methyltransferase (MGMT), death-associated protein kinase (DAPK), E-cadherin (ECAD), p14ARF, and glutathione S-transferase P1 (GSTP1) in 107 resected primary non-small cell lung cancers (NSCLCs) and in 104 corresponding nonmalignant lung tissues by methylation-specific PCR. Methylation in the tumor samples was detected in 40% for RARbeta, 26% for TIMP-3, 25% for p16INK4a, 21% for MGMT, 19% for DAPK, 18% for ECAD, 8% for p14ARF, and 7% for GSTP1, whereas it was not seen in the vast majority of the corresponding nonmalignant tissues. Moreover, p16INK4a methylation was correlated with loss of p16INK4a expression by immunohistochemistry. A total of 82% of the NSCLCs had methylation of at least one of these genes; 37% of the NSCLCs had one gene methylated, 22% of the NSCLCs had two genes methylated, 13% of the NSCLCs had three genes methylated, 8% of the NSCLCs had four genes methylated, and 2% of the NSCLCs had five genes methylated. Methylation of these genes was correlated with some clinicopathological characteristics of the patients. In comparing the methylation patterns of tumors and nonmalignant lung tissues from the same patients, there were many discordancies where the genes methylated in nonmalignant tissues were not methylated in the corresponding tumors. This suggests that the methylation was occurring as a preneoplastic change. We conclude that these findings confirm in a large sample that methylation is a frequent event in NSCLC, can also occur in smoking-damaged nonmalignant lung tissues, and may be the most common mechanism to inactivate cancer-related genes in NSCLC.

Adult↗
PubMed2001

Association of SV40 with human tumours.

SV40 was discovered as a contaminant of poliovirus vaccines that were inadvertently administered to millions of people in Europe and the United States between 1955 and 1963. Shortly afterwards, SV40 was proven to be oncogenic in rodents and capable of transforming human and animal cells in vitro. The possibility that SV40 might cause tumours in humans thus became a subject of scientific and public interest and scrutiny. However, largely due to a lack of significant epidemiological evidence, interest in assessing SV40's potential carcinogenic role in humans diminished. Recently, many laboratories have reported the presence of SV40-like DNA in a high proportion of human mesotheliomas, ependymomas and osteosarcoma (the three main types of tumours caused by virus in hamsters), renewing the question whether SV40 might be a human tumour virus. Molecular data from these studies are reviewed to re-evaluate the potential role of SV40 as a human carcinogen.

Animals↗
PubMed2001

High-resolution chromosome 3p allelotyping of breast carcinomas and precursor lesions demonstrates frequent loss of heterozygosity and a discontinuous pattern of allele loss.

We performed high-resolution allelotyping for loss of heterozygosity (LOH) analysis on microdissected samples from 45 primary breast cancers, 47 mammary preneoplastic epithelial foci, and 18 breast cancer cell lines, using a panel of 27 polymorphic chromosome 3p markers. Allele loss in some regions of chromosome 3p was detected in 39 of 45 (87%) primary breast tumors. The 3p21.3 region had the highest frequency of LOH (69%), followed by 3p22-24 (61%), 3p21.2-21.3 (58%), 3p25 (48%), 3p14.2 (45%), 3p14.3 (41%), and 3p12 (35%). Analysis of all of the data revealed at least nine discrete intervals showing frequent allele loss: D3S1511-D3S1284 (U2020/DUTT1 region centered on D3S1274 with a homozygous deletion), D3S1300-D3S1234 [fragile histidine triad (FHIT)/FRA3B region centered on D3S1300 with a homozygous deletion], D3S1076-D3S1573, D3S4624/Luca2.1-D3S4597/P1.5, D3S1478-D3S1029, D3S1029 (with a homozygous deletion), D3S1612-D3S1537, D3S1293-D3S1597, and D3S1597-telomere; it is more than likely that additional localized regions of LOH not examined in this study also exist on chromosome 3p. In multiple cases, there was discontinuous allele loss at several 3p sites in the same tumor. Twenty-one of 47 (45%) preneoplastic lesions demonstrated 3p LOH, including 12 of 13 (92%) ductal carcinoma in situ, 2 of 7 (29%) apocrine metaplasia, and 7 of 25 (28%) usual epithelial hyperplasia. The 3p21.3 region had the highest frequency of LOH in preneoplastic breast epithelium (36%), followed by 3p21.2-21.3 (20%), 3p14.2/FHIT region (11%), 3p25 (10%), and 3p22-24 (5%). In 39 3p loci showing LOH in both the tumor and accompanying preneoplasia, 34 (87%) showed loss of the same parental allele (P = 1.2 x 10(-6), cumulative binomial test). In addition, when 21 preneoplastic samples showing LOH were compared to their accompanying cancers, 67% were clonally related, 20% were potentially clonally related but were divergent, and 13% were clonally unrelated. Overall this demonstrated the high likelihood of clonal relatedness of the preneoplastic foci to the tumors. We conclude that: chromosome 3p allele loss is a common event in breast carcinoma pathogenesis; involves multiple, localized sites that often show discontinuous LOH with intervening markers retaining heterozygosity; and is seen in early preneoplastic stages, which demonstrate clonal relatedness to the invasive cancer.

Adult↗
PubMed2001

Molecular analysis of synchronous and metachronous tumors of the lung: impact on management and prognosis.

Patients with pulmonary neoplasms have an increased risk for developing a second tumor of the lung, either at the same time or different times. It is important to determine if the second tumor represents an independent primary tumor (ie, a synchronous or a metachronous tumor, depending on whether it is present at the same time or a later time) or recurrence/metastasis, because it will significantly change the management and prognosis. Because the two tumors from the same patient are often morphologically similar, histologic examination alone may not be sufficient to distinguish between the two possibilities. We have attempted to approach this problem by microdissecting malignant cells and comparing patterns of loss of heterozygosity of multiple genes and chromosomal loci between paired tumors. We found that primary tumors of the lung and their metastasis share nearly identical patterns of loss of heterozygosity. In contrast, most synchronous and metachronous tumors as defined by the current arbitrary criteria appeared to be genetically different; therefore, they likely represented independent primary tumors. Rare synchronous tumors had similar genetic profiles, raising the possibility of recurrence/metastasis. Our data suggest that molecular analysis can help fingerprint tumors and has the potential to significantly impact management and prognosis of patients.

Adenocarcinoma↗
PubMed2001

Deletions of chromosome 4 occur early during the pathogenesis of colorectal carcinoma.

Allelic losses at one or both arms of chromosome 4 are frequent in several tumor types, but information about colorectal carcinoma is limited. We have previously defined 4 nonoverlapping regions of frequent deletions in several tumor types. In an effort to more precisely locate the putative tumor suppressor gene(s) on chromosome 4 involved in the multistage pathogenesis of colorectal carcinomas, we performed loss of heterozygosity (LOH) studies using 19 polymorphic microsatellite markers. After precise microdissection of archival surgical cases, we determined LOH in DNA obtained from 23 colorectal adenocarcinomas, 20 colorectal adenomas, and from corresponding histologically normal-appearing colonic epithelial samples adjacent to the tumors and at the resection margins. We observed localized deletions of chromosome 4 at multiple regions in both carcinomas and adenomas. We identified deletions at 4 previously identified regions: R1 at 4q33-34 (18%-33%), R2 at 4q25-26 (45%-65%), R3 at 4p15.1-15.3 (35%-47%), and R4 at 4p16.3 (40%-49%). Six of fifteen (40%) cases examined with deletions of chromosome 4 in either adenocarcinomas or adenomas had loss of the same parental alleles in adjacent histologically normal epithelium but not in epithelial samples from the surgical resection margins. The deletions, which commenced on the short arm of chromosome 4 (regions R3 and/or R4), were more extensive in adenocarcinomas, intermediate in length in adenomas, and least extensive in histologically normal epithelium. Our results suggest that there may be multiple putative tumor suppressor genes located on both arms of chromosome 4 whose inactivation are important early events in the pathogenesis of colorectal carcinoma.

Adenocarcinoma↗
PubMed2001

Primary mammary small-cell carcinoma: a molecular analysis of 2 cases.

Primary small-cell carcinoma of the breast is an exceedingly rare variant of breast carcinoma whose genetic profile has not been previously investigated. We report the molecular features of 2 cases of small-cell carcinoma of the breast: 1 with an adjacent intraductal carcinoma, and 1 with prior pleomorphic lobular carcinoma in situ. Laser capture microdissection followed by loss of heterozygosity (LOH) analysis revealed identical molecular alterations at multiple chromosomal regions, including BRCA-1, BRCA-2, p53, and retinoblastoma gene loci, in 1 case of small-cell carcinoma and its adjacent intraductal component. Additionally, LOH in 1 or both small-cell carcinomas was detected at 3p, 4q31.2-qter, 8p21-24, 11q13 (MEN-1 locus), 11q23.3, 11q24.1-25, 16q24.1 (H-cadherin locus), and 17q25. The results of our molecular analysis suggest that genetic changes in mammary small-cell carcinoma resembled those seen in both invasive ductal carcinomas and pulmonary small-cell carcinoma. Second, mammary small-cell carcinoma is clonally related to ductal carcinoma in situ and might represent an example of divergent differentiation occurring in a multipotential neoplastic stem cell.

Adult↗
PubMed2001

Microdissection and the study of cancer pathways.

Abstract: The study of genetic alterations in tumors and their precursor lesions is often hampered by the presence of a heterogeneous background of non-neoplastic elements such as stromal cells, inflammatory cells, and angiogenic elements. Microdissection involves the extraction of specific populations of cells under direct visualization. In this article, we will discuss the currently available techniques of microdissection, and briefly review how this material is being utilized in the study of cancer pathways. Microdissected tissue is amenable for the study of cancer genomics, expression analysis and most recently, cancer proteomics. The purity of reagents obtained from microdissected material has resulted in the successful identification of tumor suppressor genes as well as novel transcripts and proteins that are altered in neoplastic cells. Improved techniques of tissue fixation and microdissection, supplemented with ancillary technology such as pre-amplification, have permitted the use of increasingly smaller quantities of material for the study of cancer pathways. Importantly, it is now possible to analyze many of the genetic changes that precede cancer, thereby identifying populations "at risk" for developing malignancies in the future.

Cell Separation↗
PubMed2001

Early detection of lung cancer: clinical perspectives of recent advances in biology and radiology.

Lung cancer is the most common cause of cancer death in developed countries. The prognosis is poor, with less than 15% of patients surviving 5 years after diagnosis. The poor prognosis is attributable to lack of efficient diagnostic methods for early detection and lack of successful treatment for metastatic disease. Most patients (>75%) present with stage III or IV disease and are rarely curable with current therapies. Within the last decade, rapid advances in molecular biology, pathology, bronchology, and radiology have provided a rational basis for improving outcome. These advancements have led to a better documentation of morphological changes in the bronchial epithelium before development of clinical evident invasive carcinomas. This has changed our concept of lung carcinogenesis and emphasized the multistep carcinogenesis approach on several levels. Combined with the technical developments in bronchoscopic techniques, e.g., laser-induced fluorescence endoscope (LIFE) bronchoscopy, we now have improved methods to localize preinvasive and early-invasive bronchial lesions. With the LIFE bronchoscope, a new morphological entity (angiogenic squamous dysplasia) has been recognized, which might be an important biomarker and target for antiangiogenic chemopreventive agents. To reduce the mortality of lung cancer, these new technologies have been taken into the clinic in different scientific settings. The use of low-dose spiral computed tomography in the screening of a high-risk population has demonstrated the possibility of diagnosing small peripheral tumors that are not seen on conventional X-ray. A shift in the therapeutic paradigm from targeting advanced clinically manifest lung cancer toward asymptomatic preinvasive and early-invasive cancer is occurring. The present article reviews the recent advances in the diagnosis of preinvasive and early-invasive cancer to identify biomarkers for early detection of lung cancer and for chemoprevention studies.

Aged↗
PubMed2001

Aberrant methylation during cervical carcinogenesis.

We studied the pattern of aberrant methylation during the multistage pathogenesis of cervical cancers. We analyzed a total of 73 patient samples and 10 cervical cancer cell lines. In addition, tissue samples [peripheral blood lymphocytes (n = 10) and buccal epithelial cells (n = 12)] were obtained from 22 healthy volunteers. On the basis of the results of preliminary analysis, the cervical samples were grouped into three categories: (a) nondysplasia/low-grade cervical intraepithelial neoplasia (CIN; n = 37); (b) high-grade CIN (n = 17); and (c) invasive cancer (n = 19). The methylation status of six genes was determined (p16, RARbeta, FHIT, GSTP1, MGMT, and hMLH1). Our main findings are as follows: (a) methylation was completely absent in control tissues; (b) the frequencies of methylation for all of the genes except hMLH1 were >20% in cervical cancers; (c) aberrant methylation commenced early during multistage pathogenesis and methylation of at least one gene was noted in 30% of the nondysplasia/low-grade CIN group; (d) an increasing trend for methylation was seen with increasing pathological change; (e) methylation of RARbeta and GSTP1 were early events, p16 and MGMT methylation were intermediate events, and FHIT methylation was a late, tumor-associated event; and (f) methylation occurred independently of other risk factors including papillomavirus infection, smoking history, or hormone use. Although our findings need to be extended to a larger series, they suggest that the pattern of aberrant methylation in women with or without dysplasia may help identify subgroups at increased risk for histological progression or cancer development.

Acid Anhydride Hydrolases↗
PubMed2001

Nucleotide substitution in the ectodomain of trail receptor DR4 is associated with lung cancer and head and neck cancer.

Allelic loss of chromosome 8p21-22 occurs frequently in cancer, including lung and head and neck squamous cell cancer. The tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptors, including proapoptotic DR4 and KILLER/DR5, are located on 8p21-22. TRAIL receptors are candidate tumor suppressor genes, because their inactivation would be expected to result in deficient apoptotic signaling. To investigate the involvement of DR4 in human cancer, we have determined the genomic structure of DR4 and screened 31 lung cancer cell lines [14 small cell lung cancer and 17 non-small cell lung cancer (NSCLC)], many with deletions at 8p21-22, and 21 primary NSCLC samples for mutations in DR4. We found two missense alterations in the ectodomain of DR4. One, at nucleotide 626, changes a cytosine to a guanine (C626G) and results in a substitution of an arginine for threonine. The other, at nucleotide 422, changes a guanine to adenine (G422A) and results in a substitution of a histidine for arginine. Using genomic DNA sequencing and RFLP analysis, we show that these two alterations cosegregated in 96% of all of the samples (n = 243) evaluated (tumor and normal). The frequency of being homozygous for both altered alleles was 35% in the lung cancer cell lines but only 13% in age- and race-matched controls, which was a significant increase (chi(2) = 5.2, P = 0.023). The frequency of homozygosity for both alleles was also significantly increased in the primary NSCLC samples (chi(2) = 9.2, P = 0.002) as compared with the age- and race-matched controls. To determine whether the altered alleles are specific for lung cancer, we evaluated 19 head and neck squamous cell cancer and 25 gastric adenocarcinoma samples. Forty-seven % of the former and 44% of the latter were homozygous for both the C626G and G422A alterations, and this was significantly elevated relative to age- and race-matched controls (chi(2) = 8.6, P = 0.003 and chi(2) = 8.2, P = 0.004). These alterations result in amino acid changes in or near the ligand-binding domain of DR4 and, based on the crystal structure of DR5 and its homology with DR4, have the potential to affect TRAIL binding to DR4. Our results suggest that the altered DR4 alleles may be associated with, and should be investigated additionally as potential markers for, predisposition to common malignancies.

Adenine↗
PubMed2001

Aberrant methylation of the adenomatous polyposis coli (APC) gene promoter 1A in breast and lung carcinomas.

The adenomatous polyposis coli (APC) gene is a tumor suppressor gene associated with both familial and sporadic cancer. Despite high rates of allelic loss in lung and breast cancers, point mutations of the APC gene are infrequent in these cancer types. Aberrant methylation of the APC promoter 1A occurs in some colorectal and gastric malignancies, and we investigated whether the same mechanism occurs in lung and breast cancers. The methylation status of the APC gene promoter 1A was analyzed in 77 breast, 50 small cell (SCLC), and 106 non-small cell (NSCLC) lung cancer tumors and cell lines and in 68 nonmalignant tissues by methylation-specific PCR. Expression of the APC promoter 1A transcript was examined in a subset of cell lines by reverse transcription-PCR, and loss of heterozygosity at the gene locus was analyzed by the use of 12 microsatellite and polymorphic markers. Statistical tests were two-sided. Promoter 1A was methylated in 34 of 77 breast cancer tumors and cell lines (44%), in 56 of 106 NSCLC tumors and cell lines (53%), in 13 of 50 SCLC cell lines (26%), and in 3 of 68 nonmalignant samples (4%). Most cell lines tested contained the unmethylated or methylated form exclusively. In 27 cell lines tested, there was complete concordance between promoter methylation and silencing of its transcript. Demethylation with 5-aza-2'-deoxycytidine treatment restored transcript 1A expression in all eight methylated cell lines tested. Loss of heterozygosity at the APC locus was observed in 85% of SCLCs, 83% of NSCLCs, and 63% of breast cancer cell lines. The frequency of methylation in breast cancers increased with tumor stage and size. In summary, aberrant methylation of the 1A promoter of the APC gene and loss of its specific transcript is frequently present in breast and NSCLC cancers and cell lines and, to a lesser extent, in SCLC cell lines. Our findings may be of biological and clinical importance.

Adenomatous Polyposis Coli Protein↗