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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

On the basis of morphologic and immunophenotypic studies, it is generally accepted that the lymphocyte population in thymomas is not neoplastic. We studied 10 thymomas with restriction endonuclease and Southern blot/DNA hybridization methods in an attempt to provide genotypic evidence in support of this hypothesis. The clinical, gross, and microscopic features of each case were reviewed and found to be entirely consistent with the diagnosis of thymoma. In addition to conventional histologic methods, we also studied each tumor by immunohistologic techniques. The lymphocytes generally had an immunotype characteristic of immature cortical thymocytes, and the epithelial cells were uniformly stained by antikeratin antibodies. DNA probes for the T-cell receptor beta-chain gene and immunoglobulin genes (C kappa, C lambda, and JH) were used in the genotypic studies. No gene rearrangements were detected in any of the thymomas. This study provides additional evidence that clonal proliferations of T or B lymphocytes are not present in thymomas; therefore, these cells are almost certainly not neoplastic. The results also provide a basis for the effective use of restriction endonuclease and Southern blot/DNA hybridization analysis in the differential diagnosis of non-Hodgkin's lymphoma and thymoma.
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PMID:Immunoglobulin and T-cell receptor genes in thymomas: genotypic evidence supporting the nonneoplastic nature of the lymphocytic component. 283 Nov 35

We cloned the DNA from a novel human papillomavirus (HPV) present in a cervical condyloma. When DNA from this isolate was hybridized at high stringency with HPV types 1 through 50 (HPV-1 through HPV-50), it showed weak homology with HPV-6 and -16 and stronger homology with HPV-26. A detailed restriction endonuclease map was prepared which showed marked differences from the maps for other HPVs that have been isolated from the female genital tract. Reassociation kinetic analysis revealed that HPV-26 and this new isolate were less than 10% homologous; hence, the new isolate is a novel strain of HPV. The approximate positions of the open reading frames of the new strain were surmised by hybridization with probes derived from individual open reading frames of HPV-16. In an analysis of 175 genital biopsies from patients with abnormal Papanicolaou smears, sequences hybridizing under highly stringent conditions to probes from this novel HPV type were found in 4.2, 6.1, and 2.4% of biopsies containing normal squamous epithelium, condylomata, and intraepithelial neoplasia, respectively. In addition, sequences homologous to probes from this novel isolate were detected in one of five cervical carcinomas examined.
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PMID:Isolation of a novel human papillomavirus (type 51) from a cervical condyloma. 283 6

Based on the following 3 points: 1) tumor proliferation is energy-dependent, 2) mitochondrial energy-production system is dominant for cell growth, and 3) liver mitochondria (mt) possess their own DNA and RNA synthesizing some of their own proteins including respiratory enzymes such as cytochrome oxidases, a possible relationship between mutations of mt-DNA and clinical status of cell proliferation was examined in 10 HCC patients who underwent liver resection. Mt-DNA at the cancerous and the noncancerous portions of 1g resected liver specimens were separated from the nuclear DNA, and then digested with Hinf I endonuclease. DNA filters were made of the digested mt-DNA fragments on the agarose and polyacrylamide gel. The filters were hybridized with a nick-translated 32P-labeled DNA fragments. In two cases, abnormal mt-DNA were detected. In the first case, the tumor was the massive type and grew rapidly invading the bile duct. One restriction fragment of 3.0 Kb of the cancerous and non cancerous portion became larger by 60 bp. In the second case, regarded as metachronous multicentric HCC, the second largest band of the 3.4 Kb fragment of the cancerous portion showed a wider range but not of the noncancerous portion. The former change may indicate polymorphism but the latter indicates an occurrence of the mutation of mt-DNA. Further studies are required, including examinations on the rest of mitochondrial fragments.
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PMID:[Analysis of human mitochondrial DNA in hepatocellular carcinomas]. 283 32

We isolated and characterized a type B thymotropic retrovirus (DMBA-LV) which is highly related to mouse mammary tumor virus (MMTV) isolates and which induces T-cell thymomas with a high incidence and a very short latent period. Regions of nonhomology between the DMBA-LV genome and the MMTV genome were identified by heteroduplex mapping and nucleotide sequence studies. In the electron microscope heteroduplex mapping studies the EcoRI-generated 5' and 3' fragments of the DMBA-LV genome were compared with the corresponding fragments of the MMTV (C3H and GR) genome isolated from mammary tumors. The results indicated that DMBA-LV contained a region of nonhomologous nucleotide sequences in the 3' half of the U3 region of the long terminal repeat (LTR). Nucleotide sequence studies confirmed these results and showed that in this region 440 nucleotides of the MMTV (C3H) sequences were deleted and substituted with a segment of 122 nucleotides. This substituted segment in the form of a tandem repeat structure contained nucleotide sequences derived exclusively from sequences which flanked the substitution loop. The distal glucocorticoid regulatory element was unaltered, and two additional copies of the distal glucocorticoid regulatory element-binding site were present in the substituted region. The restriction endonuclease map of the reconstructed molecular clone of DMBA-LV was identical to that corresponding to unintegrated linear DMBA-LV DNA present in DMBA-LV-induced tumor cell lines. Since the nucleotide sequences of the LTRs present in four different DMBA-LV proviral copies isolated from a single thymoma were identical, we concluded that they were derived from the same parental virus and that this type B retrovirus containing an alteration in the U3 region of its LTR could induce thymic lymphomas. Thus, DMBA-LV represents the first example of a productively replicating type B retrovirus that contains an LTR modified in the U3 region and that has target cell and disease specificity for T cells.
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PMID:Alterations in the U3 region of the long terminal repeat of an infectious thymotropic type B retrovirus. 283 15

Length variation of a ribosomal DNA "spacer" region in four chromosomally characterized transitional cell carcinoma cultures was analyzed by restriction endonuclease cleavage and Southern blotting. Cell lines with relative karyotypic conservation, such as UM-UC-2 (modal chromosome number 48, four marker chromosomes) demonstrate little change in the genetically regulated pattern of rDNA spacer length polymorphisms (7.6, 6.7 and 6.0 kilobases) which may be found in normal cells. Cell lines with more aberrant karyotypes, such as UM-UC-3 (modal chromosome number 86, 12 marker chromosomes) and UM-UC-4 (modal number 51, ten marker chromosomes) show fewer ribosomal DNA length variants (7.6, 6.7 kilobases for the former, 7.6 kilobases for the latter), consistent with relaxed constraints on the drive for ribosomal gene homogeneity through inter and intrachromosomal exchange. Uncharacterized rDNA length variants of low copy number were observed in cell lines with many marker chromosomes. Analysis of repetitive DNA structure provides an additional criterion for tumor diagnosis and staging, and a characterized series of tumor cell lines may provide a useful system for understanding repetitive DNA evolution.
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PMID:Cell-specific ribosomal DNA spacer variability in human urothelial carcinoma cultures. 287 45

We have examined the epidermal growth factor (EGF) receptor gene for structural alterations in fresh human tumors. DNA samples from 92 patients with solid tumors (lung cancer, 37; breast cancer, 24; head and neck cancer, 17; other tumors, 14) were analyzed and compared with those from 22 leukemia patients and 14 individuals without malignant neoplasms. When DNA samples were digested with HindIII restriction endonuclease, Southern blot analysis demonstrated 3 distinct polymorphic bands (9.8, 11, and 12 kilobases) after hybridization to the HER-A64-1 probe and another 2 distinct polymorphic bands (4.9 and 5.2 kilobases) after hybridization to the HER-A64-3 probe. Pedigree analysis of 43 members of a single family and comparative analysis of tumor and normal DNA samples from the same patients demonstrated that the variations in fragment size observed were due to 2 independent restriction fragment length polymorphisms in the region of the EGF receptor gene. Amplification of the EGF receptor gene was detected in 3 cases of breast cancer, but not in other tumors studied. We conclude that the human EGF receptor gene has multiple restriction fragment length polymorphisms and that in fresh human tumor samples rearrangement and amplification of the gene occur infrequently, if ever, within the region encompassed by the 2 complementary DNA probes used.
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PMID:Multiple restriction fragment length polymorphisms of the human epidermal growth factor receptor gene. 289 88

Enhanced expression of the human SIS/PDGF-2 gene has been reported in a number of human cell lines, sarcomas, and glioblastomas. We have analyzed the SIS/PDGF-2 gene for structural alterations in fresh human tumors. DNA samples from 79 patients with solid tumors (63 mesenchymal tumors, 12 lung carcinomas, 4 breast carcinomas) were examined and compared with DNA samples from 50 leukemia patients and 14 unrelated individuals without malignant neoplasms. When DNA samples were digested with a HindIII restriction endonuclease, Southern blot analysis demonstrated two distinct bands (21kb and 18kb) after hybridization to the SIS/PDGF-2 gene probe. A pedigree analysis of a 43-member family indicated that these allelic variants segregated in a Mendelian fashion. There was, however, tumor specific allele loss in 18% of the mesenchymal tumors analyzed, which may indicate a common etiology for this tumor type.
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PMID:Reduction to homozygosity at the SIS/PDGF-2 locus in human mesenchymal tumors. 290 34

Feline and human genetic sequences, homologous to the v-sis gene of simian sarcoma virus, have been isolated from cosmid gene libraries and characterized by restriction endonuclease analysis. Comparison of the two loci revealed their related structural organization. In both loci, similar unique genetic sequences were found upstream of the v-sis homologous region and these hybridized to a 4.2 kbp c-sis transcript in human lung tumor cells. These data establish and map as yet unidentified coding sequences at the 5' part of the c-sis proto-oncogene of both species.
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PMID:Comparative analysis of the human and feline c-sis proto-oncogenes. Identification of 5' human c-sis coding sequences that are not homologous to the transforming gene of simian sarcoma virus. 298 25

Rat thymic lymphomas induced by Moloney murine leukemia virus carry DNA rearrangements due to provirus integration in at least five independent cellular DNA domains (Mlvi-1, Mlvi-2, Mlvi-3, RMoInt-1, and c-myc). We had previously shown that rearrangements in more than one of these domains could occur in the same tumor. In this report we extend these findings by showing that, with one exception, tumors containing provirus insertions in Mlvi-1 always contained provirus insertions in a second locus, Mlvi-2. To determine whether both events occurred in the same population of tumor cells, we examined the clonal nature of these tumors by taking advantage of allelic polymorphisms that occur naturally in both Mlvi-1 and Mlvi-2. Tumors with provirus insertions in both Mlvi-1 and Mlvi-2 arising in rats heterozygous at one of these loci were identified. DNA from these tumors was analyzed by restriction endonuclease digestion and hybridization to DNA probes derived from both Mlvi-1 and Mlvi-2. Thus, we determined the clonal nature of three thymomas and showed that in these tumors both insertion events occurred in the same population of tumor cells. The concomitant appearance of provirus insertions in Mlvi-1 and Mlvi-2 suggests a synergism of these two events that may be important in tumor induction and progression.
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PMID:Concerted DNA rearrangements in Moloney murine leukemia virus-induced thymomas: a potential synergistic relationship in oncogenesis. 299 54

Envelope gp70s were isolated from the thymotropic recombinant viruses related to Moloney murine leukemia virus (RM-M-MuLVs) which were generated by the inoculation of two strains of ecotropic M-MuLV (strain 1869 and temperature-sensitive mutant-1) into BALB/c or CFW/D mice. Chymotrypsin oligopeptide maps of parental ecotropic MuLV, RM-M-MuLV, and inducible xenotropic MuLV showed each of the above virus types had a distinctly characteristic peptide map. The majority of RM-M-MuLV gp70 molecules examined showed a high degree of peptide homology. Data from restriction endonuclease mapping demonstrated that the newly acquired sequences in each of the RM-M-MuLVs were very related and encompassed both the polymerase and the envelope genes. The source of the sequences acquired by the RM-M-MuLV was from endogenous nonecotropic and nonxenotropic proviruses. This suggested that the family of endogenous proviruses which combined with the parental ecotropic virus was either specifically selected or was much more available than other endogenous proviruses. Although slight variations of envelope-specific sequences and peptides existed among various RM-M-MuLV isolates; within a single thymoma, individual clones of tumor cells yielded RM-M-MuLV gp70s which were identical to each other. These findings are discussed within the context of the leukemogenic potential of RM-MuLVs.
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PMID:Thymotropic envelope gene recombinants of Moloney leukemia virus have highly conserved envelope structures. 299 79


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