1,721,055 research outputs found
Expression of TRK-T1 oncogene induces differentiation of PC12 cells.
No full textThe TRK-T1 oncogene, isolated from a human thyroid carcinoma, represents a rearranged form of the high affinity nerve growth factor (NGF) receptor encoded by the NTRK1 gene; it is created by an intrachromosomal rearrangement fusing the NTRK1 tyrosine kinase domain to the 5' portion of the TPR gene. We have investigated the effect of the TRK-T1 oncogene in PC12 cells, a model system for studying neuronal differentiation and the mechanism of action of NGF. Here, we report that, in PC12 cells, the TRK-T1 oncogene has a differentiating effect that resembles that of NGF and requires the phosphorylation of the oncoprotein. Our results are consistent with the hypothesis that TRK-T1, as well as the original TRK oncogene, induces PC12 differentiation by mimicking the action of NGF bound to its receptor
TP53 Mutations and Pathologic Complete Response to Neoadjuvant Cisplatin and Fluorouracil Chemotherapy in Resected Oral Cavity Squamous Cell Carcinoma
No full textPurpose To find out if TP53 functional status predicts response to neoadjuvant chemotherapy and thus may be helpful during treatment decision making of oral cavity squamous cell carcinoma (SCC) patients. Patients and Methods We analyzed the predictive value of TP53 mutations and their functional status on the basis of the transactivation activity of p53 mutant proteins in 53 pretreatment biopsies of oral cavity SCC patients receiving primary cisplatin and fluorouracil chemotherapy followed by surgery. Results The surgical specimens showed that 15 patients (28%) achieved a pathologic complete remission (pCR) at both T and N sites, and 38 patients had residual tumor cells. Among the 53 pretreatment biopsies, 24 (45%) displayed TP53 mutations: 22 single-nucleotide substitutions and two deletions. According to functional status that could be determined only for the 22 substitutions, 21 mutations were nonfunctional and one was partially functional. TP53 mutation was found in four (27%) of 15 patients who achieved a pCR and in 20 (53%) of 38 nonresponder patients; the difference was not statistically significant (P = .12). In contrast, two (14%) of 14 cases with pCR carried a nonfunctional TP53 mutation, a frequency significantly less than that found in the nonresponders (19 [51%] of 37; P = .02). TP53 mutation predicted pCR in four (17%) of 24 patients and a nonfunctional mutation in only two (9%) of 22 patients. Conclusion The results indicate that the loss of function (transactivation activities) of p53 mutant proteins may predict a significant low pCR rate and suboptimal response to cisplatin-based neoadjuvant chemotherapy in patients with oral cavity SCC
Detection of microsatellite alterations in the spectrum of melanocytic nevi in patients with or without individual or family history of melanoma
No full textWe studied a group of patients with or without individual or family history of melanoma for the occurrence of genetic alterations at microsatellite DNA sequences, usually referred to as microsatellite instability (MSI), and loss of heterozygosity (LOH). Microsatellite analysis of 3 markers located on chromosome 9p21-22 was performed for 88 melanocytic lesions, including 27 melanomas and 35 dysplastic and 26 common nevi, from 48 patients. Three additional markers, on 11q23, 17q21 and 5q22, were investigated in 16 melanomas. Overall, microsatellite alterations of the type usually considered low-level instability at 9p21-22 were observed in 22% of melanomas and 31% of dysplastic and 23% of common nevi. LOH at the same loci was found in 15% of melanomas and 8% of dysplastic nevi but never in common nevi. Cases with a positive family history of melanoma compared to those with a negative family history showed a higher microsatellite alteration frequency (43% vs. 20%), and the same was observed in melanoma compared to non-melanoma carriers (31% vs. 16%). Our results show that (i) MSI is common in all melanocytic lesions, though with differences in the group of patients which could have clinical relevance if confirmed, whereas LOH is restricted to melanomas and dysplastic nevi; (ii) various melanocytic lesions from the same patient represent clonally distinct tumors; (iii) the phenotype suggestive of DNA repair deficiency is influenced by a family or an individual history of melanoma; (iv) the microsatellite alteration frequency correlates with patient groups ordered according to increasing melanoma risk
Molecular Cloning of PTC, a New Oncogene Found Activated in Human Thyroid Papillary Carcinomas and Their Lymph Node Metastases
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Rapid assessment of replication error phenotype in gastric cancer
No full textForty gastric tumors were investigated for microsatellite instability at the D2S119 and L-myc loci. These tumors and 143 other gastrointestinal cancers were previously analyzed for instability at several different microsatellites. By evaluating previous and present results, repeated sequences were selected that frequently underwent replication errors (RERs). To coamplify these sequences, the following multiplex polymerase chain reactions (PCRs) were performed: 1) D2S119/L-myc/D18S59; 2) D2S119/L-myc/D3S1076; and 3) D2S177/L-myc/BAT-RII. Therefore, the 40 gastric tumors in the present survey were rescreened using multiplex PCRs. Each multiplex allowed detection of nearly all RER+ tumors (80% for multiplex 3 and 87% for multiplexes 1 and 2) that had been previously identified by amplifying 9 different loci with independent reactions. Moreover, for multiplexes 1 and 2, the size differences between normal and RER alleles were sufficient to be detected by electrophoresis on conventional polyacrylamide gels after DNA staining with ethidium bromide. This approach allows a rapid and easy assessment of RER phenotype in gastric tumors
A new oncogene in human thyroid papillary carcinomas and their lymph-nodal metastases
No full textUsing DNA transfection analysis1 on NIH3T3 cells2, activated human oncogenes have been isolated from a variety of fresh solid tumours3. Thyroid neoplasias show a wide range of lesions varying from slowly progressive well-differentiated tumours to anaplastic highly malignant neoplasms4. Therefore they represent an attractive model to investigate the role of oncogene activation in different stages of the neoplastic state. Here we report the detection of transforming activity in DNAs extracted from five thyroid papillary carcinomas and two of their respective lymph-nodal metastases. © 1987 Nature Publishing Group
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