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Biomedical subjects

D Sidransky

Publications and source records attributed to D Sidransky.

At least 127 records · Page 7Linked to original sources
PubMed1997

Genetic markers for early detection of lung cancer and outcome measures for response to chemoprevention.

Lung cancer is one of the leading causes of cancer death in the world. The high mortality rate for lung cancer probably results, at least in part, from the absence of standard clinical procedures for diagnosis of the disease at early and more treatable stages compared to breast, prostate, and colon cancers. The delineation of genetic alterations that occur in lung tumorigenesis may aid in both developing molecular markers for early detection and predicting of response to chemoprevention/chemotherapy. Cytogenetic and molecular genetic studies have shown that mutations in protooncogenes and tumor suppressor genes (TSGs) are critical in the multi-step development and progression of lung tumors. Inactivation of TSGs are by far the most common mutational events documented during the development of lung cancer. For example, loss of function of the Rb and/or p53 genes has been detected in both small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). In addition, allelic loss analyses have implicated the existence of other tumor suppressor gene loci on 9p as well as on 3p, 5q, 8p, 9q, 11q, 11q, and 17q. We examined the short arm of chromosomes 3 and 9 for TSG loci by analyzing 23 squamous cell carcinomas of the lung with numerous microsatellite markers. On chromosome 9p, loss of heterozygosity was detected in all of the 23 tumors and homozygous deletions of the p16/CDKN2 locus were detected in 6 of the 23 (26%) tumors. In addition, a novel region of homozygous deletion was detected in 6 of the tumors (26%) at D9S126. The homozygous deletion of D9S126 was confirmed by fluorescent in situ hybridization (FISH) analysis of tumor tissue touch preparations and isolated nuclei using P1 and cosmid probes that contain D9S126. Only one tumor harbored a homozygous deletion at both the p16/CDKN2 locus and the D9S126 locus. The data identify a region of homozygous loss on the short arm of chromosome 9, suggesting the presence of a novel TSG locus approximately 2.5 cM proximal to p16/CDKN2. On chromosome 3p, a similar high percentage of the tumors exhibited loss of heterozygosity. Also, homozygous deletions were detected in several tumors at 3p21.3. Thus, FISH analysis with probes containing the D9S126 or p16 locus could be used as molecular markers to assay sputum samples for premalignant cells exfoliated from the bronchial epithelium. Probes from other chromosome regions such as 3p21 could be used in a similar manner.

Chemoprevention↗
PubMed1997

Impact of chromosome 14q loss on survival in primary head and neck squamous cell carcinoma.

We screened 73 primary head and neck squamous cell carcinoma (HNSCC) specimens for loss of heterozygosity (LOH) on chromosome 14q. Analysis of 20 polymorphic microsatellite markers identified 29 (40%) HNSCCs exhibiting LOH of 14q in at least one locus. Six tumors had probable monosomy of 14q, displaying allelic loss for all informative markers tested, and 23 demonstrated partial losses on 14q. Fine mapping with 1-10 additional markers revealed two poorly defined regions of loss (4-7 cM) at 14q13-21 and 14q31-32.1 in seven tumors. In 53 patients with previously untreated tumors treated with curative intent, LOH of 14q in these tumors correlated with poor survival. Compared to patients with tumors that retain heterozygosity of 14q, those with 14q LOH had a 3-fold increased risk of death in multivariate analysis (hazards ratio, 3.2; 95% confidence interval = 1.2-8.4). These data have confirmed a high frequency of chromosome 14q loss in HNSCC and suggest that LOH of any region on chromosome 14q is an indicator of poor outcome.

Adult↗
PubMed1997

Comparison of oncogene mutation detection and telomerase activity for the molecular staging of non-small cell lung cancer.

Novel oncogene mutation detection techniques have demonstrated that standard histopathological examination may fail to detect clinically significant metastatic cancer cells. Recently, telomerase activity has been detected in most immortal cell lines and human tumors, potentially providing a novel diagnostic marker. We compared standard histopathological examination with the telomeric repeat amplification protocol assay and either a p53 plaque hybridization or a K-ras mutation ligation assay in the lymph nodes of 12 patents with surgically resectable non-small cell lung cancer. Telomerase activity was detected in 10 of 10 (100%) evaluable tumors. Eight of 9 (89%) histopathologically positive lymph nodes were telomerase positive, and 26 of 48 (54%) histopathologically negative lymph nodes were telomerase positive. In comparison, oligonucleotide plaque hybridization detected metastases in all 3 histopathologically positive nodes and in 3 of 27 histopathologically negative nodes. Similarly, the K-ras mutation ligation assay detected metastases in all 6 histopathologically positive lymph nodes examined and in 1 of 21 histopathologically negative lymph nodes. Thus, most of the "positive" nodes by telomerase assay did not harbor occult neoplastic cells that shared the same genetic alteration as the primary tumor. The high rate of false positives associated with the telomeric repeat amplification protocol assay limits its role in staging lymph nodes in patients with non-small cell lung cancer.

Adult↗
PubMed1996

An allelotype of papillary thyroid cancer.

Although papillary carcinoma accounts for approximately 70% of all thyroid cancers, preliminary studies of allelic loss have thus far not identified any areas of chromosomal deletion. We evaluated 30 papillary thyroid carcinomas for chromosomal loss/allelic imbalance by testing at least 2 microsatellite markers from every autosomal arm. Fifteen of the 30 tumors tested exhibited loss of heterozygosity/allelic imbalance (LOH/AI) at one or more loci. Chromosomal arms with frequent LOH/AI included 4q, 5p, 7p and 11p. An average of 1.1 chromosomal arms displayed LOH/AI in each individual tumor. Therefore, 4q, 5p, 7p and, to a lesser extent, 11p display significant LOH/AI in papillary thyroid cancer, which indicates the presence of putative tumor-suppressor gene loci at these chromosomal arms.

Alleles↗
PubMed1996

Detection of telomerase activity in oral rinses from head and neck squamous cell carcinoma patients.

Telomerase is a ribonucleoprotein that maintains telomere length and whose activity is associated with escape from cellular senescence. Telomerase activity has been found in germline, immortalized, and malignant tumor cells. Using a modified PCR-based assay for telomerase activity, 26 of 35 (80%) primary, fresh, head and neck squamous cell cancer specimens and 3 of 6 head and neck squamous dysplastic lesions possessed telomerase activity. In addition, 14 of 44 (32%) oral rinses from a separate group of head and neck squamous cell cancer patients contained detectable telomerase activity, whereas 1 of 22 (5%) oral rinses from normal control patients exhibited telomerase activity. Telomerase activity in oral rinses was compared with corresponding activity in paired primary tumor samples for 19 cases: 7 of 19 demonstrated activity in both tumor and oral rinse, 2 of 19 lacked activity in both tumor and oral rinse, 10 of 19 tumors demonstrated activity that could not be detected in corresponding oral rinses, and there were no examples of positive oral rinses with corresponding negative tumors. Although currently limited in its sensitivity, analysis of telomerase activity in oral rinses represents a novel method to detect the presence of cancer cells shed in the upper aerodigestive tract.

Carcinoma, Squamous Cell↗
PubMed1996

p53 mutation and locoregional treatment failure in head and neck squamous cell carcinoma.

BACKGROUND: The p53 gene (also known as TP53) may be the most common genetic target involved in the malignant transformation of human cells. Direct sequence analysis has demonstrated that alteration of this gene occurs in approximately 45% of head and neck squamous cell carcinomas. The consequences of p53 mutations in these cancers with respect to tumor behavior and patient survival have not been rigorously determined. PURPOSE: We evaluated the implications of p53 mutations in relation to the control of locoregional disease and overall survival following radiation therapy. METHODS: Data from 110 consecutive patients with invasive disease who were treated with primary radiation therapy (given with curative intent) or with adjuvant radiation therapy (following complete surgical extirpation of gross disease) were included in the analysis. A 1.8-kilobase fragment of the p53 gene encompassing exons 5-9 was amplified from the DNA of stored (frozen) tumor specimens; the amplified DNA was cloned and sequenced by use of standard techniques. Overall survival and locoregional disease-free survival after the completion of radiation therapy were estimated by the Kaplan-Meier method; survival comparisons were made by use of the logrank test or proportional hazards regression models. Reported P values are two-sided. RESULTS: Fortyeight (44%) of the 110 tumors had cells bearing p53 mutations. The risk of locoregional recurrence following either primary or adjuvant radiation therapy was significantly greater (i.e., the time to recurrence was shorter) for patients whose tumors contained mutant p53 genes (univariate model hazard ratio [HR] for p53 mutation versus wild-type = 2.2; 95% confidence interval [CI] = 1.2-4.1; P = .02). The presence of regional lymph node metastases (presence versus absence, HR = 2.0; 95% CI = 1.0-4.2; P = .05) and treatment type (primary radiation therapy versus surgery plus adjuvant radiation therapy, HR = 2.3; 95% CI = 1.2-4.3; P = .01) were also associated with greater risks of locoregional failure. The presence of p53 mutations and lymph node metastases and treatment with primary, as opposed to adjuvant, radiation therapy remained significant risk factors in multivariate regression analysis. No relationship was demonstrated between p53 status and overall survival (mutant versus wild-type, HR = 1.1; 95% CI = 0.6-2.1; P = .66); however, a relationship was shown for tumor stage and overall survival (stages III and IV [more advanced] versus stages I and II [less advanced], HR = 3.3; 95% CI = 1.0-10.8; P = .05). Mutation of the p53 gene was not associated with patient age, sex, tumor stage, primary tumor site, regional lymph node status, degree of tumor cell differentiation, or treatment method. CONCLUSIONS: Mutation of the p53 gene is associated with an increased risk of locoregional failure in patients with invasive head and neck squamous cell carcinoma who are treated with radiation therapy.

Carcinoma, Squamous Cell↗
PubMed1996

High-density mapping of chromosomal arm 1q in renal collecting duct carcinoma: region of minimal deletion at 1q32.1-32.2.

Collecting duct carcinoma (CDC) of the kidney is a rare malignant neoplasm of distal nephron origin. Previous studies of CDC have shown loss of heterozygosity on chromosomal arm 1q in 57% of the cases studied. To better characterize 1q loss in CDC, we performed high-density mapping of the entire long arm of chromosome 1 in 13 CDC tumor samples. We observed complete deletion of chromosomal arm 1q in 5 samples and partial deletion in 4 additional tumors. Our study further showed that the region of minimal deletion is located at 1q32.1-32.2. Sixty-nine percent (9 of 13) of the tumors showed loss of heterozygosity in this area. These data suggest that a gene or group of genes that contribute to the development of distal nephron tumors may be located within the 1q32.1-32.2 region.

Chromosome Deletion↗
PubMed1996

p16 and p16 beta are potent growth suppressors of head and neck squamous carcinoma cells in vitro.

p16 (CDKN2/MTS1/p16INK4a) is frequently deleted, methylated, or mutated in many malignancies including squamous cell carcinoma of the head and neck (HNSCC). p16 beta is an alternative transcript derived from a newly described exon (exon 1 beta) located more than 15 kb 5' to exon 1 of p16. Moreover, the p16 beta transcript theoretically encodes a protein distinct from p16 derived from a divergent reading frame putatively initiated in exon 1 beta. To test the contribution of both of these transcripts in carcinogenesis, full-length cDNA of p16 and p16 beta were cloned in separate vector constructs and then transfected into HNSCC cell lines characterized for p16 status (p16[+/+], p16[mut/-], and p16[methylated]). Transfection of either p16 or p16 beta resulted in marked growth inhibition in all three HNSCC lines tested, regardless of p16 status. However, p16 beta but not p16 inhibited the growth of HeLa cells, a cell line with inactive pRB due to expression of E7 papillomavirus protein. Moreover, transfection of all three HNSCC lines with either p16 or p16 beta resulted in a marked increase in cells in G0-G1 consistent with a cell cycle arrest in G1. These data are consistent with the hypothesis that p16 and p16 beta are growth-inhibitory genes active in HNSCC and that both act by blocking progression through the G1-S transition of the cell cycle. Furthermore, the suppressive effects of p16 beta on HeLa growth suggest that p16 beta mediates its effect independently from pRB.

Alternative Splicing↗
PubMed1996

High frequency of p16 (CDKN2/MTS-1/INK4A) inactivation in head and neck squamous cell carcinoma.

The tumor suppressor gene p16 (CDKN2/MTS-1/INK4A) can be inactivated by multiple genetic mechanisms. We analyzed 29 invasive primary head and neck squamous cell carcinomas (HNSCC) for p16 inactivation with immunohistochemistry utilizing a new monoclonal antibody (mAb), DCS-50. p16 staining of the primary lesions was correlated with genetic analysis including: (a) detailed microsatellite analysis of markers at the p16 locus to detect homozygous deletion; (b) sequence analysis of p16; and (c) Southern blot analysis to determine the methylation status of the 5' CpG island of p16. Twenty-four of 29 (83%) head and neck squamous cell carcinoma tumors displayed an absence of p16 nuclear staining using immunohistochemistry. Of these 24 tumors, we found that 16 (67%) harbored homozygous deletions, 5 (21%) were methylated, 1 displayed a rearrangement at the p16 locus, and 1 displayed a frameshift mutation in exon 1. These data suggest that: (a) inactivation of the p16 tumor suppressor gene is a frequent event in squamous cell carcinomas of the head and neck; (b) p16 is inactivated by several distinct and exclusive events including homozygous deletion, point mutation, and promoter methylation; and (c) immunohistochemical analysis for expression of the p16 gene product is an accurate and relatively simple method for evaluating p16 gene inactivation.

Blotting, Southern↗
PubMed1996

Multiple head and neck tumors: evidence for a common clonal origin.

Patients with head and neck cancers have a high (2-3%/year) incidence of second primary lesions. Clinically, these new lesions are identified either simultaneously with the primary lesion (synchronous) or after a period of time (metachronous). This observation has been attributed to the concept of "field carcinogenesis," which is based on the hypothesis that prolonged exposure to carcinogens leads to the independent transformation of multiple epithelial cells at several sites. An alternative theory is based on the premise that any transforming event is rare; following initial transformation, the progeny of the transformed clone spread through the mucosa and give rise to geographically distinct but genetically related tumors. We analyzed the pattern of X-chromosome inactivation in multiple primary tumors from eight female patients with head and neck cancer. In addition, we used microsatellite analysis to examine the pattern of allelic loss on chromosomes 9p and 3p, identified as early events in the progression of head and neck malignancies. In four of four cases, multiple tumors demonstrated the same pattern of X-chromosome inactivation. In the remaining four cases, X-chromosome deletions prevented interpretation (n = 3), or the androgen receptor locus was noninformative (n = 1). In three of nine patients, multiple tumors displayed the same pattern of loss of heterozygosity, two with identical breakpoints on chromosome 9p. In one patient, there was an identical microsatellite alteration at a 3p locus, definitive evidence that these tumors arose from the same clone. Our findings suggest that in at least a proportion of patients with head and neck cancers, multiple primary tumors arise from a single clone.

Chromosomes, Human, Pair 3↗
PubMed1996

Genetic progression model for head and neck cancer: implications for field cancerization.

A genetic progression model of head and neck squamous cell carcinoma has not yet been elucidated, and the genetic basis for "field cancerization" of the aerodigestive tract has also remained obscure. Eighty-seven lesions of the head and neck, including preinvasive lesions and benign lesions associated with carcinogen exposure, were tested using microsatellite analysis for allelic loss at 10 major chromosomal loci which have been defined previously. The spectrum of chromosomal loss progressively increased at each histopathological step from benign hyperplasia to dysplasia to carcinoma in situ to invasive cancer. Adjacent areas of tissue with different histopathological appearance shared common genetic changes, but the more histopathologically advanced areas exhibited additional genetic alterations. Abnormal mucosal cells surrounding preinvasive and microinvasive lesions shared common genetic alterations with those lesions and thus appear to arise from a single progenitor clone. Based on these findings, the local clinical phenomenon of field cancerization seems to involve the expansion and migration of clonally related preneoplastic cells.

Carcinoma, Squamous Cell↗
PubMed1996

DPC4 gene in various tumor types.

We recently identified a novel tumor-suppressor gene, DPC4, at chromosome 18q21.1 and found that both alleles of DPC4 were inactivated in nearly one-half of the pancreatic carcinomas. Here, we analyzed 338 tumors, originating from 12 distinct anatomic sites, for alterations in the DPC4 gene. Sixty-four specimens were selected for the presence of the allelic loss of 18q and were further analyzed for DPC4 sequence alterations. An alteration of the DPC4 gene sequence was identified in one of eight breast carcinomas and one of eight ovarian carcinomas. These results indicate that whereas DPC4 inactivation is prevalent in pancreatic carcinoma (48%), it is distinctly uncommon (< 10%) in the other tumor types examined. The tissue restriction of alterations in DPC4, as in many other tumor-suppressor genes, emphasizes the complexity of rate-limiting checkpoints in human tumorigenesis.

Chromosomes, Human, Pair 18↗
PubMed1996

Two tracks but one race? Cancer genetics.

The tumor suppressor gene encoding the cyclin-dependent kinase inhibitor p16 has, remarkably, been found to encode a second protein, p19, with a distinct sequence translated from an alternative reading frame; like p16, p19 can block the cell cycle in G1 phase.

Animals↗
PubMed1996

Distal nephron renal tumors: microsatellite allelotype.

Tumors of varying malignant potential arise from the complex epithelial lining of the nephron. Although the molecular characteristics of renal clear cell carcinomas, which arise from the proximal tubule, have been studied, little is known about tumors that develop from other parts of the renal tubular system. To elucidate common molecular lesions that may contribute to the development or progression of nonproximal tubule renal tumors, we performed a detailed microsatellite allelotype of lesions thought to arise from the renal collecting duct. Eighteen collecting duct carcinomas (CDCs) and 13 renal oncocytomas were studied using highly informative microsatellite markers on all autosomal arms. Loss of heterozygosity (LOH) was identified on multiple chromosomal arms in CDCs and renal oncocytomas. Microsatellite analysis revealed LOH of 1q in 57% of informative CDCs. LOH was also observed on arms 6p (45%), 8p (40%), and 21q (40%). In renal oncocytomas, LOH of 1q occurred in approximately 30% of tumors, but 1p LOH was observed in 57% of informative cases analyzed. High levels of LOH were also observed on arms 8p, 14q, 19q, and 21q in the oncocytomas studied. Loss of chromosomal arm 3p was infrequent in both tumor types. Our results suggest that the molecular events that contribute to the development of distal nephron tumors are distinct from those associated with the etiology of proximal tubule renal cancers.

Adenoma, Oxyphilic↗
PubMed1996

Genetic divergence in the clonal evolution of breast cancer.

The progression of ductal carcinoma in situ (DCIS) to infiltrating and metastatic cancer of the breast is thought to be a consequence of clonal expansions of neoplastic cells with progressively more genetic alterations. To study this progression, we first dissected multiple foci from each of 23 breast tumors with DCIS only and 20 cases with synchronous DCIS and infiltrating cancer. We than tested microsatellite markers by PCR for allelic losses in the individual foci for loci on chromosomes 6q, 9p, 11q, 13q, 16q, 17q, and 17p. The patterns of allelic losses identified in the in situ cancers were generally conserved in the synchronous infiltrating tumors, supporting the paradigm that the infiltrating tumors are clonally derived from the in situ lesions. However, in 8 (40%) of the 20 cases with synchronous in situ and invasive cancer, heterogeneous patterns of allelic loss at one or more chromosomal loci were observed in adjacent DCIS foci. Moreover, some of the allelic losses recognized in in situ portions of the tumors were not conserved in the clonal progression to the synchronous invasive tumor. Such allelic loss heterogeneity was noted in only 1 of the 20 infiltrating tumors and only 3 of the 23 cases of DCIS without invasion that were studied in a similar manner. This heterogeneity indicated genetic divergence during the clonal evolution of breast cancer, particularly at the time when in situ cancers progress to invasive cancers.

Breast Neoplasms↗
PubMed1996

Allelotype of salivary gland tumors.

To elucidate the genetic alterations that occur in salivary gland tumors, we screened every autosomal arm (and the X-chromosome) of 29 primary human salivary gland neoplasms (11 pleomorphic adenomas, 10 adenoid cystic carcinomas, 5 mucopidermoid carcinomas, and 3 carcinomas ex-mixed tumors) for allelic loss using 86 microsatellite markers. A minimum of two microsatellite markers were used per chromosomal arm to achieve informativity of at least 60% (excluding X). The pleomorphic adenomas demonstrated few areas of allelic loss; the most prominent chromosomal arm involved was 12q, lost in more than 35% of informative cases. The most significant allelic losses in adenoid cystic carcinoma were 1p, 2p, 6q, 17p, and 20p (>20% of informative cases) and 19q (40% of informative cases). Mucoepidermoid carcinoma showed 50% or greater loss at 2q, 5p, 12p, and 16q. Although losses at 9p, 3p, and 17p are common in squamous cell carcinoma of the head and neck, only the carcinoma ex-mixed tumors demonstrated loss at these loci, consistent with progression to a more aggressive phenotype. Salivary gland tumors display allelic loss patterns different from many other tumor types, suggesting distinct genetic pathways in the progression of these tumors.

Alleles↗
PubMed1996

Molecular detection of primary bladder cancer by microsatellite analysis.

Microsatellite DNA markers have been widely used as a tool for the detection of loss of heterozygosity and genomic instability in primary tumors. In a blinded study, urine samples from 25 patients with suspicious bladder lesions that had been identified cystoscopically were analyzed by this molecular method and by conventional cytology. Microsatellite changes matching those in the tumor were detected in the urine sediment of 19 of the 20 patients (95 percent) who were diagnosed with bladder cancer, whereas urine cytology detected cancer cells in 9 of 18 (50 percent) of the samples. These results suggest that microsatellite analysis, which in principle can be performed at about one-third the cost of cytology, may be a useful addition to current screening methods for detecting bladder cancer.

Adult↗