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Query: UMLS:C0178874 (tumor progression)
 40,807 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tumorigenesis and tumor progression can be considered an evolutionary process. In order to deduce information on the mutational and selective pressures during melanoma progression we performed microsatellite analysis at 42 autosomal and two X-linked loci in a microdissected primary melanoma and its nine metastases. Loss of heterozygosity at locus D9S259 was the only genetic change observed in all metastases. The pattern of loss of heterozygosity at loci D9S162 and D9S171 within the region of common loss on chromosome 9p21 which encompasses the tumor suppressor gene p16ink4 enabled the distinction of four genetically different tumor cell populations. Three cell lineages showed homozygous loss of the p16ink4 gene, which evolved independently in each tumor cell population within the primary tumor. Additional allele losses could be demonstrated at markers D14S53 and DXS998. The fourth lineage did not demonstrate loss of heterozygosity at loci D9S162 and D9S171 and contained the wild type p16ink4 gene but was characterized by abundant microsatellite instability. The evolutionary approach towards tumorigenesis and tumor progression used in this study thus confirms the role of p16ink4 inactivation for melanoma progression but not for melanoma initiation; it suggests the existence of additional putative tumor suppressor genes located on 9p as well as on the long arm of chromosome 14 and shows that microsatellite instability may represent an alternative pathway of tumor cell evolution in malignant melanoma.
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PMID:Analysis of tumor cell evolution in a melanoma: evidence of mutational and selective pressure for loss of p16ink4 and for microsatellite instability. 1062 Jan 9

Barrett's esophagus carries a 30- to 100-fold increased risk of adenocarcinoma, which is thought to develop via a metaplasia-dysplasia-carcinoma progression. A common genetic abnormality detected in Barrett's adenocarcinoma is loss of heterozygosity (LOH) at the sites of known or putative tumor suppressor genes, of which there are at least 9 associated with esophageal adenocarcinoma. The aim of this study was to identify at which histological stage of carcinogenesis LOH at these sites occur. Microdissection of multiple paraffin-embedded tissue blocks from 17 esophagogastrectomy specimens of adenocarcinoma arising in Barrett's esophagus yielded areas of metaplasia, low-, intermediate- and high-grade dysplasia, and carcinoma. LOH analysis of microdissected tissues was performed using a double polymerase chain reaction technique with 11 microsatellite primers shown previously to have LOH in at least 30% of esophageal adenocarcinomas. Identical LOH was detected in premalignant and malignant tissues in 4 of 17 patients, and was located at 5q21-q22 (D5S346 primer), 17p11.1-p12 (TCF2 primer), 17p13.1 (TP53 primer), 18q21.1 (detected in colon cancer tumor suppressor gene [DCC] primer), and 18q23-qter (D18S70 primer). These results suggest that LOH at the sites of the DCC, adenomatous polyposis coli (APC), and TP53 tumor suppressor genes occur before the development of adenocarcinoma in Barrett's esophagus, and so merit further study as potential biomarkers of neoplastic progression in patients with Barrett's esophagus undergoing endoscopic and histological surveillance.
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PMID:LOH at the sites of the DCC, APC, and TP53 tumor suppressor genes occurs in Barrett's metaplasia and dysplasia adjacent to adenocarcinoma of the esophagus. 1066 31

We developed a model of human urinary bladder cancer progression from in situ precursor lesions to invasive carcinoma using whole organ histologic and genetic mapping. The model represents a high-density and detailed analysis regarding allelic losses on chromosomes 4, 8, 9, 11, and 17 as revealed by testing of 234 samples obtained from five cystectomy specimens. The samples corresponded to microscopically identified intraurothelial precursor conditions ranging from dysplasia to carcinoma in situ and invasive cancer. The initial analysis of paired normal and tumor DNA samples disclosed allelic losses in 72 of 225 tested hypervariable DNA markers. Subsequent use of these markers on all mucosal samples revealed that 47 had alterations with a statistically significant relation to urothelial neoplasia. The allelic losses clustered in 33 distinct chromosomal regions, indicating the location of putative tumor suppressor genes involved in the development and progression of urinary bladder cancer. Some of the markers with statistically significant allelic losses mapped to the regions containing well-characterized tumor suppressor genes but many were located in previously unknown loci. The majority of statistically significant allelic losses (70%) occurred early in low-grade intraurothelial dysplasia, and some of them involved adjacent areas of morphologically normal mucosa preceding the development of microscopically recognizable precursor lesions. The remaining 30% of markers developed allelic losses in the later phases of urothelial neoplasia, implicating their involvement in progression to invasive disease. Markers exhibiting allelic losses in early phases of urothelial neoplasia could be used for detection of occult preclinical or even premicroscopic phases of urinary bladder cancer, whereas markers that showed allelic losses in the later phases of the process could serve as indicators of progression to invasive disease. The approach used in this study facilitates genome-wide modeling of cancer progression and provides important chromosomal landmarks for more specific studies of multistep urinary bladder carcinogenesis.
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PMID:Genetic modeling of human urinary bladder carcinogenesis. 1071 70

Allelic losses on the long arm of human chromosome 6 are frequently observed in cancers of the ovary, prostate, and breast. To identify the locations of putative tumor suppressor genes on 6q, we examined 192 primary breast cancers for patterns of allelic loss at 16 polymorphic microsatellite loci distributed along this chromosome arm. Allelic losses at one or more loci were observed in 105 (55%) of the tumors examined. Detailed deletion mapping with appropriate yeast artificial chromosome (YAC) contigs identified two distinct commonly deleted regions; one was confined to a 1-cM interval at 6q21 flanked by D6S1040 and D6S262 and the other to a 1-cM interval at 6q25.3 flanked by D6S305 and D6S411. Allelic losses at 6q21 were more frequent in invasive solid tubular and scirrhous carcinomas than in tumors of less aggressive histologic types (P = 0.0006). Allelic loss at 6q25.3 was associated with loss of progesterone receptor (P = 0.0256). Our results suggest the presence of two tumor suppressor genes for breast cancer on 6q that are likely to be associated with tumor progression and / or loss of hormonal dependency.
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PMID:Mapping of target regions of allelic loss in primary breast cancers to 1-cM intervals on genomic contigs at 6q21 and 6q25.3. 1076 Jun 88

Genetic alterations of the long arm of chromosome 11 have been implicated in melanoma pathogenesis, and we recently identified two distinct regions of common allelic loss in chromosomal band 11q23. To establish the point in time of melanoma tumorigenesis at which these two putative tumor suppressor loci become relevant, we investigated allelic loss [loss of heterozygosity (LOH)] in both chromosomal regions in tumors of progressing patients. We analyzed 102 tumor samples from 23 patients for whom at least two (10 patients) or three (13 patients) tumor samples from different clinical progression steps (such as primary tumor and/or in-transit metastasis and/or regional lymph node metastasis and/or distant metastasis) were available. We detected no 11q23 LOH at any stage in 3 of 23 patients and detected LOH at all stages tested in 8 of 23 patients. In 8 of the remaining 12 (67%) patients with 11q23 LOH at some stage during tumor progression, we found this to occur first at regional lymph node metastasis. Two of these patients retained constitutional heterozygosity in several in-transit metastases that developed up to 7 months after lymph node metastases that already had loss. We therefore conclude that 11q23 LOH is associated with regional lymph node metastasis in melanoma. Finally, we detected an allele shift restricted to a histomorphologically distinct part of a primary melanoma and found that the same parental chromosome was affected by allelic loss in a subsequently occurring lymph node metastasis. These findings support our conclusion and give additional evidence for the hypothesis of molecular heterogeneity of early tumor cell populations in melanoma.
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PMID:11q23 allelic loss is associated with regional lymph node metastasis in melanoma. 1095 7

Carcinoid tumors are rare neuroendocrine tumors occurring in the lung or in the digestive tract where they are further subclassified as foregut, midgut, or hindgut carcinoids. To gain a better understanding of the genetic basis of the different types of carcinoid tumors, we have characterized numerical imbalances in a series of midgut carcinoids, and compared the results to previous findings in carcinoids from the lung. Numerical imbalances were revealed in 16 of the 18 tumors, and the most commonly detected aberrations were losses of 18q22-qter (67%), 11q22-q23 (33%), and 16q21-qter (22%), and gain of 4p14-qter (22%). The total number of alterations found in the metastases was significantly higher than in the primary tumors, indicating the accumulation of acquired genetic changes in the tumor progression. Losses of 18q and 11q were present both in primary tumors and metastases, whereas loss of 16q and gain of 4 were only detected in metastases. Furthermore, the pattern of comparative genomic hybridization alterations varied depending on the total number of detected alterations. Taken together, the findings would suggest a progression of numerical imbalances, in which loss of 18q and 11q represent early events, and loss of 16q and gain of 4p are late events in the tumor progression of midgut carcinoids. When compared to previously published comparative genomic hybridization abnormalities in lung carcinoids, loss of 11q was found to occur in both tumor types, whereas loss of 18q and 16q and gain of 4 were not revealed in lung carcinoids. The results indicate that inactivation of a putative tumor suppressor gene in 18q22-qter represents a frequent and early event that is specific for the development of midgut carcinoids.
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PMID:Comparative genomic hybridization identifies loss of 18q22-qter as an early and specific event in tumorigenesis of midgut carcinoids. 1133 78

We previously applied arbitrarily primed polymerase chain reaction DNA fingerprinting to identify molecular genetic alterations in primary breast carcinomas. One of the most frequently observed fingerprint alterations was a reduction in the intensity of the MCG1-B2 band in 32% of tumors, indicating recurrent loss of X-chromosome segments. This article reports a mapping analysis of those chromosomal deletions. The subchromosomal origin of MCG1-B2 was determined to be the Xq25 chromosomal region. Loss of heterozygosity (LOH) analysis was carried out on 72 infiltrating ductal carcinomas with a panel of seven microsatellite markers spanning Xq25. The smallest common region of the X-chromosome deletions was mapped to between markers DXS8059 and DXS8009, with the highest LOH frequency of 52.4% at the DXS8098 locus. The LOH at DXS8098 was associated with larger tumor size (> 3 cm) (P = 0.048, Fisher exact test), higher histologic grade (P = 0.036, Fisher exact test), and axillary lymph node metastasis (P = 0.020, Fisher exact test). These results suggest that the Xq25 region harbors a putative tumor suppressor gene whose inactivation in breast cancer is associated with tumor progression and metastasis. LOH at this region, therefore, potentially could be used as a prognostic marker for disease development. One of the two X chromosomes is transcriptionally silent in women. The loss of the Xq25 region detected in this study occurred preferentially on the inactive X chromosome. This suggests that the putative tumor suppressor gene may escape X inactivation.
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PMID:Frequent loss Xq25 on the inactive X chromosome in primary breast carcinomas is associated with tumor grade and axillary lymph node metastasis. 1180 83

The proportions of mutation of BRCA1 and BRCA2 detected in familial breast cancer vary in different regions. Most breast cancer families in Sweden cannot be explained by mutations in the known major susceptibility genes. Our previous studies have found a high frequency of LOH in the Tp53 region in familial breast cancer suggesting a putative tumor suppressor gene in this region, and the Tp53 gene was excluded as predisposing gene in these families by mutation screening. In order to identify other candidate tumor suppressor genes responsible for familial breast cancer, we performed LOH analysis in 98 paired tumor and blood samples from 91 breast cancer families using 11 microsatellite markers on chromosome 17p. Two loci with high frequency of LOH were found. One spanned the Tp53 gene, the other was distal to Tp53. Linkage studies were performed on 17p with 11 microsatellite markers in 102 breast cancer families with no detectable mutations in the BRCA1 and BRCA2 gene. The linkage analysis did not further support any of the regions suggested by the LOH study. However, since the Tp53 gene is already known to predispose to breast cancer as well as being involved in tumor progression, it is possible that also this region, close but distal to Tp53 contains a gene involved in familial and/or sporadic breast cancer development similar to Tp53.
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PMID:A region close to Tp53 shows LOH in familial breast cancer. 1189 37

The 18q chromosome arm is frequently lost in advanced head and neck squamous cell carcinoma. Twenty-four microsatellite markers located on chromosome 18q were genotyped in 145 primary tumors and 10 cell lines in order to identify putative tumor suppressor genes implicated in tumor progression. Two different minimal common regions of loss (MCRL) were identified at 18q22 and 18q23 respectively. To refine and delineate boundaries of an homozygous deletion found in one cell line, 44 extra markers located at 18q22 were analysed and the homozygous deletion was precisely defined within a critical region of 4.9 Mb. Four known genes (CDH7, CDH19, DNAM-1, FLJ23594) located in this critical region and two EST clusters (Hs.96900, Hs.98628) were selected for further investigations. For these six genes, genomic structures were established, somatic mutations were screened in 20 HNSCC and 10 cell lines and transcription levels were determined in eight cell lines. No somatic mutations were found in any of the candidate genes analysed (57 coding exons). However, differential transcription levels were observed for CDH19 and Hs.96900 in head and neck cancer cell lines supporting their putative involvement through down regulation mechanisms in head and neck cancer progression.
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PMID:Delineation and candidate gene mutation screening of the 18q22 minimal region of deletion in head and neck squamous cell carcinoma. 1211 82

Mutational activation of KIT or PDGFRA is considered an early step in pathogenesis of gastrointestinal stromal tumors (GISTs); however, other nonrandom genetic changes have also been identified. At least three common regions of deletions on chromosome 22q, which may harbor putative tumor suppressor genes, have been defined. However, mapping of these regions has been inconsistent. It has also been speculated that GI autonomous nerve tumors (GANTs), GISTs with ultrastructural features suggestive of autonomic nerve differentiation, are characterized by a specific deletion involving 22q13 cytogenetic region. This study was undertaken to evaluate loss of heterozygosity (LOH) on chromosome 22q in 50 GISTs, including 10 GANTs. Four tumors were incidental minimal lesions <or=10 mm in diameter. LOH was evaluated using 20 PCR-based microsatellite markers and capillary gel electrophoresis. In all, 15 (30%) cases showed LOH of more than 75% of informative markers, suggesting loss of chromosome 22q. A total of 24 GISTs (50%) revealed LOH of one to seven informative markers clustered in different loci suggesting simultaneous involvement of different regions. The highest frequency of LOH was seen at D22S922 and D22S425, mapped to 22q13.33 and 22q11.22, respectively. However, LOH at other regions including IL2RB and NF2 locus was also found. No NF2 mutations were identified in four analyzed tumors. LOH on chromosome 22q was more frequent among intestinal than among gastric GISTs; however, there was no difference between LOH pattern seen in tumors defined by different histologic, ultrastructural (GANT) and molecular features (KIT and PDGFRA mutations). Although minimal GISTs revealed LOH on chromosome 22q, there was a higher LOH frequency in malignant than in benign tumors. An isolated LOH at D22S425 was equally found in both benign and malignant tumors. These observations may suggest that LOHs on chromosome 22q in GISTs play a role in early stages of tumor formation as well as in late tumor progression.
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PMID:Loss of heterozygosity on chromosome 22q in gastrointestinal stromal tumors (GISTs): a study on 50 cases. 1558 Feb 84


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