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

Carcinogenesis is a multistage process that has been characterized both by the activation of cellular oncogenes and by the loss of function of tumor suppressor genes. Colorectal cancer has been associated with the activation of ras oncogenes and with the deletion of multiple chromosomal regions including chromosomes 5q, 17p, and 18q. Such chromosome loss is often suggestive of the deletion or loss of function of tumor suppressor genes. The candidate tumor suppressor genes from these regions are, respectively, MCC and/or APC, p53, and DCC. In order to further our understanding of the molecular and genetic mechanisms involved in tumor progression and, thereby, of normal cell growth, it is important to determine whether defects in one or more of these loci contribute functionally in the progression to malignancy in colorectal cancer and whether correction of any of these defects restores normal growth control in vitro and in vivo. To address this question, we have utilized the technique of microcell-mediated chromosome transfer to introduce normal human chromosomes 5, 17, and 18 individually into recipient colorectal cancer cells. Additionally, chromosome 15 was introduced into SW480 cells as an irrelevant control chromosome. While the introduction of chromosome 17 into the tumorigenic colorectal cell line SW480 yielded no viable clones, cell lines were established after the introduction of chromosomes 15, 5, and 18. Hybrids containing chromosome 18 are morphologically similar to the parental line, whereas those containing chromosome 5 are morphologically distinct from the parental cell line, being small, polygonal, and tightly packed. SW480-chromosome 5 hybrids are strongly suppressed for tumorigenicity, while SW480-chromosome 18 hybrids produce slowly growing tumors in some of the animals injected. Hybrids containing the introduced chromosome 18 but was significantly reduced in several of the tumor reconstitute cell lines. Introduction of chromosome 5 had little to no effect on responsiveness, whereas transfer ot chromosome 18 restored responsiveness to some degree. Our findings indicate that while multiple defects in tumor suppressor genes seem to be required for progression to the malignant state in colorectal cancer, correction of only a single defect can have significant effects in vivo and/or in vitro.
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PMID:Progression of colorectal cancer is associated with multiple tumor suppressor gene defects but inhibition of tumorigenicity is accomplished by correction of any single defect via chromosome transfer. 134 43

To search for specific chromosome 8 aberrations in human prostate cancer, DNA was isolated from 44 human prostate tumor samples. Twenty six tumor samples were obtained from locally progressive tumors by transurethral resection, 12 were from radical prostatectomy specimens, and 6 were from lymph node metastases. Tumor DNAs were screened for allelic losses using 16 highly polymorphic microsatellite loci (14 covering the p arm, 2 on the q arm). In general, the detected deletions were large. In 59% of the tumor DNAs, allelic loss of 3 or more 8p loci was observed. Loss of 8p loci occurred in between 36 and 69% of the informative cases; for the two 8q markers, the percentages of loss were 11 and 25%, respectively, indicating preferential loss of (part of) 8p. In one tumor, two separate 8p deletions were found. The percentage of loss of heterozygosity was considerably higher in transurethral resection (65%) and lymph node metastases (83%) than in radical prostatectomy specimens (33%), suggesting that 8p deletion is a relatively late step in tumor progression. The maximal overlapping deleted region in all tumor DNAs is between the distal locus D8S133 and the proximal locus D8S87, indicating the localization of a candidate tumor suppressor gene within this region.
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PMID:Loss of heterozygosity of chromosome 8 microsatellite loci implicates a candidate tumor suppressor gene between the loci D8S87 and D8S133 in human prostate cancer. 795 46

A new method of differential expression cloning called differential display (DD) has been used to screen for novel tumor suppressor genes involved in breast cancer. The screen is based on positive selection at the mRNA level for genes expressed in normal mammary epithelial cells but decreased or lost in corresponding tumor cells. A candidate tumor suppressor gene recovered by DD is integrin alpha-6 (alpha 6), a component of the heterodimeric integrin receptors alpha 6 beta 1 and alpha 6 beta 4. Loss of alpha 6 expression was confirmed in total RNAs by Northern blot analysis and by immunostaining with alpha 6 antibodies. Consistent with these cell culture findings, previous immunostaining of mammary tissue sections has identified decreased alpha 6 protein expression during breast tumor progression. Southern blot analysis demonstrated that alpha 6 gene is present in tumor cell lines, suggesting that reexpression may be inducible by pharmacological intervention. The likelihood that alpha 6 may have tumor suppressing activity is supported by growing evidence of a central role for integrins in transducing growth control and differentiation signals from growth factors and the extracellular matrix (ECM).
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PMID:Identification by differential display of alpha 6 integrin as a candidate tumor suppressor gene. 834 95

The detection of loss of heterozygosity, indicative of the presence of a tumor suppressor gene, has been reported to occur frequently on chromosome 22q in human ovarian cancer. In this study, 110 sporadic ovarian tumors were analyzed using 8 polymorphic loci to define a minimum region of loss. Fifty-eight (53%) tumors showed loss of heterozygosity, and of these 6 exhibited partial loss, enabling the identification of two candidate tumor suppressor gene loci. One region, of less than 0.5 cM, is flanked by D22S284 and CYP2D, and a second region lies distal to D22S276. Analysis of loss of heterozygosity with respect to grade and stage suggests that chromosome 22q loss of heterozygosity is of more relevance in tumor progression rather than initiation.
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PMID:Localization of an ovarian cancer tumor suppressor gene to a 0.5-cM region between D22S284 and CYP2D, on chromosome 22q. 863 Oct 2

A deletion analysis of chromosome 3 was conducted in 72 cases of transitional cell carcinoma of the urinary bladder using seven microsatellites spanning the 3p arm and two additional microsatellites in 3q. Results showed that 19 of 72 (26.4%) cases had deletions in one or more 3p regions. Two regions of frequent deletion were identified: 3p12-14 and 3p21-23. Less frequent deletions at 3p24.2-25 were also observed. Deletions at 3p were weakly correlated with tumor grade, but strongly with pathological stage. Among 70 cases with histological grade available, 4 of 29 (13.8%) grade 1 and 2 tumors, and 15 of 41 (36.6%) grade 3 tumors showed allelic losses in one or more of the 3p regions studied (P = 0.055). Among 69 cases with pathological stage available, none of 27 superficial carcinomas (pTa, pTis, and pT1) showed 3p deletions, whereas 18 of 42 (42.9%) muscle invasive lesions (pT2, pT3, and pT4) displayed allelic losses at 3p (P < 0.001). In addition, 12 cases showed microsatellite instability, but there was no correlation between abnormalities and tumor grade or stage. No correlation was found between deletions at 3p21-23 and microsatellite instability. In conclusion, deletions at three discrete regions of 3p were identified in bladder carcinoma, suggesting the involvement of candidate tumor suppressor genes residing in these regions. Moreover, detection of allelic losses in these regions was associated with higher tumor grade and more advanced stage, suggesting their potential involvement in bladder tumor progression.
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PMID:Chromosome 3 allelic losses and microsatellite alterations in transitional cell carcinoma of the urinary bladder. 868 47

The selective loss of maternal and reduplication of paternal chromosome 11p15.5 alleles in Wilms' tumors (WTs) points to the existence of a paternally imprinted tumor suppressor gene(s) and/or a maternally imprinted dose-dependent growth-promoting gene(s) in this chromosomal region. Two reciprocally imprinted chromosome 11p15.5 genes, H19, a candidate tumor suppressor gene, and IGF2, a candidate dominant oncogene, have been well-characterized in terms of their imprinting and expression status in WTs. Here we review and extend data indicating that a majority of WTs show a bipaternal epigenotype at these loci, with H19 inactive and IGF2 biallelically active. This can arise either through loss of heterozygosity (LOH) or by a non-LOH pathway involving localized biallelic hypermethylation of H19 DNA. Conversion to this bipaternal endpoint has recently been found to affect not only these two genes, but also at least one other imprinted 11p15.5 gene, KIP2. Since 11p15.5 LOH and biallelic H19 hypermethylation can occur both early and late in tumor progression and since early loss is not associated with bilaterality or multifocality of WTs, these types of lesions appear to be permissive rather than rate-limiting in Wilms' tumorigenesis.
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PMID:Genomic imprinting and Wilms' tumor. 882 77

There are three nearly ubiquitous genomic "imbalances" in prostate cancer cells: 1) loss of sequences from the short arm of chromosomes 8, 2) loss of sequences from the long arm of chromosome 13q, and 3) gain of sequences on the long arm of chromosome 8, particularly in advanced disease. Candidate tumor suppressor genes and oncogenes affected by this trio of consistent changes include the c-myc gene on chromosome 8q24, the RB gene at 13q14, and potentially multiple novel genes on the short arm of chromosome 8, with a gene located more proximally potentially involved in tumor initiation and a gene or genes located more distally involved in tumor progression. Loss of regions of chromosomes 2q, 5q, 6q, 7p and 7q, 9p, 10p and 10q, 16q, 17p and 17q, and 18q, and gain of regions of 1q, 2p, 3p and 3q, 7p and 7q, 11p, 17q, and Xq have also been detected in the range of 25-50% of tumors studied. Analysis of candidate tumor suppressor genes in these regions is still in its early stages. Similarly, potential oncogenes on a series of chromosomal arms which undergo frequent amplification remain essentially uncharacterized. The basic outline of the chromosomal aberrations in prostate cancer has been well established; the details of the story remain to be filled in. This paper reviews the advantages and disadvantages of various techniques for detection of genomic loss and gain in prostate cancer cells, and reviews published reports of loss and gain in prostate cancer, focusing primarily on reports using microsatellite analysis, Southern analysis, and comparative genomic hybridization. Fluorescence in situ hybridization (FISH) based analyses of selected regions are also reviewed.
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PMID:Review of allelic loss and gain in prostate cancer. 891 74

The deleted in colorectal cancer (DCC) gene, a candidate tumor suppressor gene on chromosome 18q21, encodes a neural cell adhesion molecule family protein that is most highly expressed in the nervous system. To address the hypothesis that DCC may play a role in glioma development and/or progression, we examined DCC expression by immunohistochemistry in 57 resected human astrocytic tumors. Overall, low-grade astrocytomas were predominantly DCC positive (15 of 16, or 94%), whereas high-grade tumors significantly less often expressed the DCC protein (27 of 41, or 66%; P = 0.03). We were able to directly assess the relationship between DCC expression and tumor progression in 15 patients who initially presented with a low-grade astrocytoma and subsequently recurred with a glioblastoma. Within this panel of paired lesions from the same patient, 14 of 15 (93%) low-grade tumors expressed the DCC protein, whereas only 7 of 15 (47%) corresponding glioblastomas were DCC positive. We also observed that secondary glioblastomas resulting from malignant progression of low-grade astrocytomas were more often DCC negative (8 of 15, or 53%) compared with primary or de novo glioblastomas (6 of 26, or 23%; P = 0.05). These findings implicate DCC inactivation in glioma progression and also demonstrate that DCC expression is preferentially, but not exclusively, lost in the genetic pathway to secondary glioblastoma multiforme.
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PMID:Loss of DCC expression and glioma progression. 901 60

Expression genetics is a conceptually different approach to the identification of cancer-related genes than the search for mutations at the genome level. While mutations lie at the heart of cancer, at least in its early stages, what is recognized here are phenotypic changes usually many steps removed from the initiating mutation. Classically cancer geneticists have concentrated on genomic changes and have ignored the productive potential of examining downstream events based on screening for differential gene expression between tumor cells and well matched normal counterparts. Genes involved in cancer affect the normal functions of many cellular processes: not only proliferation but cell-cell and cell-matrix interactions, DNA repair, invasion and motility, angiogenesis, senescence, apoptosis, and others. Yet very few cancer-related genes affecting these processes have been identified in human cancers by classical methods to find mutated genes despite enormous efforts. I report here our success in readily isolating more than 100 candidate tumor suppressor genes from human tissue, estimated to represent roughly 20% of the total genes recoverable by this approach. Half of the genes are unknown and the other half include representatives of most known cancer processes. Because their expression is lost during cancer progression, they may be useful tumor markers for diagnosis and prognosis. Because these genes are not mutated, they provide opportunities for pharmacological intervention by inducing their reexpression.
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PMID:Expression genetics in cancer: shifting the focus from DNA to RNA. 902 63

A cytogenetically visible interstitial deletion of chromosome band 10q23 was found in a 6-year-old boy with mental retardation, dysmorphic features, and juvenile polyposis coli. In order to map this patient's deletion physically, we performed fluorescence in situ hybridization by using yeast artificial chromosomes (YACs) in the vicinity of the deletion. Five YACs that span an 11-15 cM region within the deletion were identified. This patient's deletion contains the putative locus for Cowden syndrome and a recently discovered candidate tumor suppressor gene (MMAC1 or PTEN) that has been implicated in the progression of a variety of human malignancies. Furthermore, the deletion is near and possibly overlaps a locus associated with juvenile polyposis. The findings in this patient with a constitutional 10q23 deletion raise the issue of whether there are separate genes in this region that are involved in Cowden syndrome, Bannayan-Riley-Ruvalcaba syndrome, juvenile polyposis, and tumor progression, or whether all of these entities could be due to a single gene.
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PMID:Deletion 10q23.2-q23.33 in a patient with gastrointestinal juvenile polyposis and other features of a Cowden-like syndrome. 949 22


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