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Query: UMLS:C0677930 (primary tumor)
 20,210 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We developed a sensitive technique of detecting circulating tumor cells in carcinoma patients, using CD45 immunomagnetic separation to isolate epithelial cells in blood samples and specific polymerase chain reaction analysis to identify point mutations of the K-ras gene. The method is based on the fact that the peripheral blood mononuclear cells (PBMC) that express CD45 antigen are trapped with anti-CD45 conjugated supramagnetic microbeads while the carcinoma cells that do not express CD45 antigen are not trapped and pass through the magnetic fields. This method concentrated the number of carcinoma cells 3.3 times. After this separation, the modified method of mutant allele specific amplification was applied and this method was able to ten control carcinoma cells in a background of 107 PBMC. A preliminary clinical study demonstrated that six cases of end-stage carcinoma with K-ras mutations in the primary tumor showed the same mutations in the peripheral blood samples, while two cases without K-ras mutation in the primary tumor and 10 healthy volunteers showed no mutation in the peripheral blood samples. The results suggest that this method may be very useful to detect circulating carcinoma cells in the patient whose primary tumor shows K-ras mutations.
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PMID:Detection of ras gene mutations in peripheral blood of carcinoma patients using CD45 immunomagnetic separation and nested mutant allele specific amplification. 959 95

It is widely recognized that various oncogenes and tumor suppressor genes contribute to tumorigenesis and progression of osteosarcomas. However, whether genetic alternations enable us to predict the prognosis of patients with osteosarcomas is unclear. Southern blotting and polymerase chain reaction/single strand conformation polymorphism (PCR-SSCP) analyses were performed to search for MDM2, ras family and p53 gene alterations in 17 patients with high-grade osteosarcomas. Amplification of the MDM2 gene was found in three tumors, two of which were obtained from a regional lymph node metastasis and the other from a locally advanced lesion. Point mutations of the p53 gene were found in exons 4 and 5 in two tumors each. One of the four tumors with p53 mutations was obtained from a lymph node metastasis, one from a recurrent tumor and another from the primary tumor of a patient who developed lung metastases. Coexistence of MDM2 amplification with point mutation of the p53 gene was observed in two tumors. A point mutation of the K-ras oncogene was detected at codon 13 in two tumors. MDM2 amplification and p53 mutation may reflect tumor progression, although no correlation between alteration and response to chemotherapy or patient survival was demonstrated.
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PMID:Clinicopathologic implications of MDM2, p53 and K-ras gene alterations in osteosarcomas: MDM2 amplification and p53 mutations found in progressive tumors. 979 60

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.
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PMID:Comparison of oncogene mutation detection and telomerase activity for the molecular staging of non-small cell lung cancer. 981 1

Activating mutations within the K-ras gene have been found in up to 90% of pancreatic carcinomas. Although multiple Ras effector pathways have been identified, the Raf protein kinases which are upstream regulators of the mitogen-activated protein kinases (MAPK/Erk) are believed to be the primary mitogenic effectors. Constitutive upregulation of this pathway by oncogenic ras is thought to promote cellular transformation. To explore the biological effects of mutated K-ras, we analyzed the Ras signaling pathway in a panel of cell lines derived from human pancreatic carcinomas. We found that despite high levels of Ras-GTP in each cell line expressing mutant K-ras, elevated levels of active Erk1 and Erk2 were not detectable under conditions of exponential growth or serum-starvation. Depending upon the cell line, the block in Erk signaling was observed to occur at either the level of Raf or Erk. Increased levels of active Erk1 and Erk2 were detected in only 2 out of 10 normal tissue-matched primary pancreatic tumors with mutated K-ras. Our results suggest that Erk signaling is not aberrantly upregulated in pancreatic cancers containing oncogenic K-ras mutations. The lack of Erk activation observed in both cell lines and primary tumor tissue suggests that constitutive Erk activation may not be required for tumor maintenance or progression in K-ras transformed pancreatic cells. We hypothesize that other Ras-dependent signaling pathways or an unidentified Raf/Mek-dependent pathway may be important for carcinogenesis in the pancreas. These findings may have important implications for drug treatment strategies which currently target the MAP kinase branch of the Ras signaling pathway.
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PMID:Lack of elevated MAP kinase (Erk) activity in pancreatic carcinomas despite oncogenic K-ras expression. 1040 37

Alterations in the Rb pathway have been described in many different tumors. In order to study this cell cycle regulatory mechanism in murine T cell lymphomas, we have analyzed the RNA and protein expression of the cyclin D1, cdk4 and retinoblastoma genes in primary tumor samples. We have detected overexpression of the cyclin D1 gene and deficient expression of the retinoblastoma gene in 42 and 28% of these tumors, respectively. The immunohistochemical analysis showed that these RT-PCR results are correlated with a significant increase in the number of positive cells for cyclin D1 and a moderate decrease in the expression of Rb protein, respectively. The analysis of cyclin D1, Rb, p15(INK4b) and p16(INK4a) showed that 75% of lymphomas had alterations in these genes and indicates that the Rb pathway is frequently altered in mouse primary T cell lymphomas. Moreover, 31% of lymphomas presented simultaneous alterations in at least two of these genes, suggesting the importance of concurrent alteration of different Rb pathway regulators. In addition, we have characterized these samples for mutational status of the N-ras and K-ras genes. We have only detected mutations in codon 12 of K-ras in six of 49 lymphomas (12%). Interestingly, five of these lymphomas also showed alterations in at least one of the Rb pathway regulators analyzed here. Taken together, these data suggest that deregulation of the Rb pathway regulators and/or oncogenic activation of K-ras may represent a common important clue in progression of murine T cell lymphomas.
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PMID:Cooperative alterations of Rb pathway regulators in mouse primary T cell lymphomas. 1046 10

Adenocarcinoma of the pancreas generally remains an incurable disease by available treatment modalities, demanding the development of a suitable cell-culture/animal model and the discovery and evaluation of novel therapeutic agents. We report the clonal preservation of a human pancreatic cell line (KCI-MOH1) established from a 74-year-old African-American man diagnosed with pancreatic cancer. Initially the human primary tumor was grown as a xenograft in SCID mice and, subsequently, a cell line was established from tumors grown as a xenograft as reported in our earlier publication. The molecular characterization of the primary tumor, the tumors grown as xenograft, and the cell line all revealed similar genotypic properties. By using an automated DNA sequencer, a K-ras mutation (codon 12, GGT to CGT, Gly to Arg) was detected in the pancreatic tumor tissue taken from the patient, whereas no p53 mutation was detected. The same K-ras mutation and unaltered p53 was also found in the xenograft tumor and in the KCI-MOH1 cell line. Chromosome analysis of the cultured cells revealed: 42,XY,add(3)(p11.2),der(7)t(7;12) (p22;q12),-10,-12,add (14)(p11),-18,add (20)(q13),-22/84, idemx2, which is the same chromosome complement found in xenograft tumors. The KCI-MOH1 cell line grows well in tissue culture and forms tumors in the SCID mice when implanted subcutaneously, as well as in orthotopic sites. The KCI-MOH1 cell line-derived SCID mouse xenograft model was used for efficacy evaluation of bryostatin 1, auristatin-PE, spongistatin 1, and gemcitabine alone and in combination. Tumor growth inhibition (T/C expressed as percentage), tumor growth delay (T - C), and log 10 kill for these agents were 38%, 22 days, and 0.53; 15%, 30 days, and 0.80; 24%, 25 days, and 0.66; and 10%, 33 days, and 0.90, respectively. When given in combination, two of seven gemcitabine + auristatin-PE-treated animals were free of tumors for 150 days and were considered cured. Animals treated with a combination of bryostatin 1 and gemcitabine and a combination of spongistatin and gemcitabine produced remissions in only one of seven mice. From these results, we conclude that (a) this is the first study illustrating that clonal characteristics of primary pancreatic tumors remained unchanged when implanted in mice and as a permanent cell line grown in vitro; and (b) there is a synergistic effect between gemcitabine and selected marine products tested in this study, which is more apparent in the gemcitabine and auristatin-PE combination. The results of this preliminary study suggest that these agents should be explored clinically in the treatment of pancreatic cancer.
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PMID:Clonal preservation of human pancreatic cell line derived from primary pancreatic adenocarcinoma. 1054 95

A new method for detecting circulating tumor cells that is based on magnetic-activated cell separation (MACS) and nested mutant allele-specific amplification (nested MASA) was evaluated in patients with colorectal cancer using the p53 and K-ras genes as genetic markers. By negative selection with anti-CD45 monoclonal antibody-conjugated supermagnetic microbeads, the proportion of tumor cells was enriched 9-fold. By the combination of MACS and nested MASA, 10 tumor cells in 10(7) normal peripheral blood mononuclear cells could be detected without false-positives. Using this method, we examined blood taken from the tumor drainage veins of 23 patients with colorectal cancer. Eighty-seven percent (20/23) of primary tumor tissues showed p53 and/or K-ras gene mutations. Forty-five percent (9/20) of patients with p53 and/or K-ras mutations in the primary tumor showed the same mutated genes in the blood samples. There was a significant association between the presence of p53 and K-ras gene mutation in the blood and tumor size, depth of invasion, and venous invasion. Blood gene mutation was detected in 80% (4/5) of samples from patients with synchronous liver metastases. Sixty percent (3/5) of patients with mutant genes in the blood developed asynchronous liver metastases after surgery. The overall survival of patients with p53 and/or K-ras gene mutation-positive findings in blood was significantly shorter than that of patients testing negative on Kaplan-Meier analysis. Our results suggest that the method may be useful for reliable detection of tumor cells circulating in the blood and may help to identify patients at high risk for relapse.
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PMID:Detection of tumor cells in blood using CD45 magnetic cell separation followed by nested mutant allele-specific amplification of p53 and K-ras genes in patients with colorectal cancer. 1095 7

In order to assess the suitability of cryopreserved neoplastic tissues for xenografting into nude (nu/nu) mice, we compared the take rate in 28 samples of pancreatic ductal carcinoma. Eleven fresh samples were implanted in nu/nu mice, and 17 were frozen in cryopreserving solution and implanted at a later time. All samples were examined for the presence of neoplastic tissue in cryostat sections. A total of 15 tumors grew in the animals; five from the freshly implanted samples and ten from those cryopreserved. Ten xenografted tumors were characterized for alterations in p53, K-ras, and p16 genes, which were found in six, eight, and nine cases, respectively. Our results demonstrate that the take rate for xenografting is comparable between cryopreserved and fresh tissue samples. The procedure allows for the exchange of tumor material between institutions and permits the establishment of centralized facilities for the storage of an array of different primary tumor samples suitable for the production of in vivo models of cancers.
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PMID:Successful xenografting of cryopreserved primary pancreatic cancers. 1125 17

Colorectal carcinogenesis is widely accepted as one of the best-characterized examples of stepwise progression. The existing colorectal carcinogenesis model assumes genetic homogeneity of individual tumors for the main known genetic alterations: K-ras and p53 genes point mutations and loss of heterozygosity (LOH) of chromosome 5q and 18q. The object of the present study was to demonstrate the existence of an intratumor genetic heterogeneity in advanced sporadic colorectal carcinoma for these genetic alterations. Using improved tissue microdissection and DNA extraction, for each tumor, amplifiable DNA was obtained from 15 to 20 areas, of which 1 to 2 concerned lymph node metastases (LNM). This study revealed that 10 of 15 (67%) analyzed tumors were heterogeneous for at least 1 genetic alteration, with between 2 and 6 genotypically different clones detected per tumor. No correlation was observed between the genotype of these subclones and histological differentiation or invasive propensity. Intratumor heterogeneity was more frequently observed for LOH than for point mutations, 67% and 58% for LOH at APC and DCC locus, and 20% for mutation of either the K-ras or p53 gene. In 5 of the 9 (56%) heterogeneous cases with available LNM, the genotype observed in the LNM was different from that of the main clone in the primary tumor, and moreover, 2 of the LNM displayed a genotype undetected in the primary tumor. In conclusion, intratumor genetic heterogeneity was demonstrated in advanced sporadic colorectal carcinoma and was represented as topographically distinct genotypic subclones. Taking into account such a significant genetic heterogeneity of colorectal tumors, the use of genetic markers for prognosis management should be reconsidered.
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PMID:Intratumor genetic heterogeneity in advanced human colorectal adenocarcinoma. 1143 98

The clonal development of colorectal carcinoma resulting from specific mutations in certain oncogenes and/or tumor suppressor genes is a well-accepted model. It is increasingly recognized that a majority of colorectal cancers are polyclonal on the basis of molecular analysis that demonstrates cells with different mutations within a given oncogene or tumor suppressor gene in the same tumor. This polyclonal pattern may occur as a result of either clonal convergence or divergence during the many steps of oncogenesis. Further complicating this picture is the fact that metastatic lesions may arise from only one of the clonal populations within a tumor and thereby present only a partial molecular make-up of the whole tumor. There are few data available that define clonal selection or specificity of circulating tumor cells in patients undergoing curative resection of colorectal carcinoma. The purpose of this paper is to describe the clonal distribution of circulating tumor cells in four patients with multiple K-ras mutations present in the primary lesion. Patients were selected who were known to have polyclonal primary colorectal cancers resected for cure. All patients had multiple mutations present in exon one, codon 12 and/or 13, of the K-ras gene. Blood samples were drawn immediately before surgery and at 2-week to 6-month intervals postoperatively. Epithelial cells were isolated from peripheral blood mononuclear cells using Dynal Immunobeads coated with antiepithelial antibodies. DNA was extracted from these cells and analyzed for all K-ras mutations present in codons 12 and 13 of the patient's primary tumor using allele-specific polymerase chain reaction followed by Microwell Array Diagonal Gel Electrophoresis. Circulating tumor cells were identified in all four patients. However, in each case of positive circulating cells the only mutation identified was an aspartic acid mutation at codon 13. Once positive the circulating tumor cells persisted in subsequent multiple blood samples. These results provide further strength for the theory of polyclonal progression in primary colorectal cancers, although there may be specific mutational patterns that confer the ability to metastasize. The significance of this persistence of the glycine-to-aspartic acid mutation at codon 13 remains to be defined given that none of these patients has clinical evidence of recurrent cancer at the time of this report.
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PMID:K-ras mutational analysis of polyclonal colorectal cancers identifies uniclonal circulating tumor cells. 1151 May 88


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