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Query: UMLS:C0242379 (lung cancer)
 71,905 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The functional properties of Myc proteins are likely to be modulated by interactions with other nuclear proteins. One such protein called Max has already been characterized (1). Through their homologous helix-loop-helix and leucine zipper structures, Myc and Max proteins form heterodimers that bind to specific DNA sequences more efficiently than Myc or Max alone. We have recently identified delta Max, a naturally occurring truncated version of Max, which is also able to dimerize with Myc in the nucleus, but is cytoplasmic in the absence of Myc. These two forms of Max can act either as enhancers or suppressors of cotransformation by c-myc and ras. Oncogenic activation of myc genes in human cancer involves deregulated myc expression. Oncogenes of the myc family are activated in several types of human tumors as a result of gene amplification or chromosomal translocation. We have recently characterized a gene fusion and a chimeric protein product formed by L-myc and part of a novel gene called rlf in small-cell lung cancer (SCLC) cell lines. Although the chimeric mRNAs were shown to be identical, they result from distinct DNA rearrangements. We have also established a physical linkage between normal rlf and L-myc using pulsed field gel electrophoresis. Thus, the rlf-L-myc gene fusions are due to similar but not identical intrachromosomal rearrangements at 1p32. Similar in vivo rearrangements involving rlf and L-myc have been found in at least one primary SCLC tumor. The presence of independent genetic lesions that cause the formation of identical chimeric rlf-L-myc proteins suggests a role for the fusion protein in the development of these SCLC tumors.
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PMID:myc, max, and a novel rlf-L-myc fusion protein in small-cell lung cancer. 166 90

We examined Southern blot analysis of genomic DNAs from 70 patients with sporadic renal cell carcinoma, using the human L-myc oncogene fragment as a hybridization probe. Our purpose was to study the relationship between the restriction fragment length polymorphism (RFLP) of the L-myc and the frequencies of metastasis. The patients were classified into 3 genotypes according to the polymorphic patterns defined by two alleles (L-L:17, L-S:31, S-S:22). The relative ratios of the 3 genotypes in the renal cancer patients were similar to those seen in healthy Japanese. However, of 20 patients who exhibited distant metastases at diagnosis, only 2 belonged to the L-L type. The incidence of distant metastasis in L-L type patients was significantly lower than that in L-S and S-S patients (p = 0.068, by Fisher's exact probability test). These results basically correspond to the previous findings in the lung cancer patients [Kawashima et al.: Proc. natn. Acad. Sci. USA 85: 2353-2356, 1988]. On the other hand, L-myc RFLP analysis in 50 prostatic cancer patients revealed that the incidence of metastasis at diagnosis did not correlate with L-myc genotypes. L-myc RFLP seems to be less promising in prostatic cancer than in lung or kidney cancer.
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PMID:Restriction fragment length polymorphism of the L-myc gene and susceptibility to metastasis in genitourinary cancers. 168 40

Altered and deregulated cellular oncogenes were found in many human solid tumors. Except for a few types of tumors that consistently exhibited specific altered proto-oncogenes, the majority of tumors are associated with a number of transcriptionally activated cellular oncogenes. In the heterologous group of non-small-cell lung cancer (NSCLC), nothing about a specific pattern of proto-oncogene expression is known. Therefore, we investigated the expression of a panel of cellular oncogenes in NSCLC cell lines. DNA and RNA from 11 established NSCLC cell lines (4 adenocarcinoma cell lines, 3 squamous cell carcinoma cell lines, 3 large-cell carcinoma cell lines and 1 mesothelioma cell line) were isolated and analysed using the Southern, dot blot and Northern hybridization technique. c-myc RNA expression was found in all NSCLC cell line, L-myc expression only in 1 adenocarcinoma cell line, N-myc and c-myb expression in none of the 11 cell lines examined. No c-myc amplification could be detected in the DNAs. v-sis-related mRNA was observed in 5/11 cell lines without association to a specific NSCLC subtype. v-src-related mRNA, found in all tested cells, exhibited increased levels in 1 adenocarcinoma cell line (A-549) compared to the other cell lines. Binding sites for epidermal growth factor (EGF) had been described previously in NSCL, therefore we found erbB homologue transcripts coding for the EGF receptor in all NSCLC cell lines. Also, c-raf1-, N-ras-, Ki-ras-, and H-ras-related RNA expression was observed in all lines. We conclude that L-myc, N-myc, and c-myb expression does occur less frequently in NSCLC than in SCLC. Also amplification does not appear to be an important mechanism by which the c-myc proto-oncogene is activated in NSCLC. A specific pattern of oncogene expression could not be detected in NSCLC cells; each cell line examined showed its own pattern. However, transcriptional activation of a proto-oncogene like erbB, ras, raf, src, and c-myc, which are all involved in the progression pathway of EGF, may be a common feature of NSCLC.
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PMID:Different pattern of expression of cellular oncogenes in human non-small-cell lung cancer cell lines. 169 Feb 10

Molecular analysis of the human proto-oncogene L-myc revealed a complex pattern of gene expression including alternative splicing and polyadenylation site selection of mRNA, giving rise to at least four mRNAs. These mRNAs in turn can code for several proteins. In this report, we characterize and define the origins of the major L-myc proteins. In vitro translation revealed that (i) two L-myc proteins (p59 and p65) were derived through alternative translational initiation at a non-AUG (CUG) site in intron 1 and at an AUG site in exon 2 of L-myc, and that (ii) extensive post-translational phosphorylation of these proteins yielded three additional proteins (p60, p66, and p68). Transfection experiments in rat embryo cells revealed the in vivo existence of this unusual CUG-initiated protein and demonstrated that it possessed transforming activity. Further, immuno-precipitation using high titered anti-L-myc peptide antisera, of two L-myc expressing small-cell lung cancer cell lines revealed three major L-myc proteins (p60, p66 and p68) all of which were derived from extensive phosphorylation of a p59 protein.
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PMID:A complex pattern of translational initiation and phosphorylation in L-myc proteins. 184 44

Examples of practical approaches to molecular epidemiology of human cancer are described. Biomarkers of carcinogen exposure or inherited host factors for cancer susceptibility are discussed. Major advances have been made in the detection of carcinogenmacromolecular adducts through the use of high performance liquid chromatography, immunoaffinity chromatography, the 32P-postlabeling assay, enzyme immunoassays, gas chromatography/mass spectroscopy and synchronous spectrophotofluorimetry. The polycyclic aromatic hydrocarbon-DNA adducts are the most extensively studied in this field and together with antibodies to these adducts found in human serum, they have become useful indicators of exposure to carcinogens. Assays for various kinds of alkyl-DNA adducts have also been developed and the presence of these adducts have been documented in human tissues. Carcinogen-protein adducts have proven to be useful molecular dosimeters of carcinogen exposure. For example, 4-aminobiphenyl hemoglobin adducts are highly correlated with exposure to tobacco smoke. The study of the molecular aspects of interindividual differences in the metabolism and activation of xenobiotics and other genetic markers [DNA-restriction fragment length polymorphisms (RFLPs), mutations, and functional loss of specific genes in carcinogenesis] is an emerging new field that is discussed in the context of genetic susceptibility to cancer. The cytochrome P450 phenotypes and acetylation phenotype are examples of genetic markers that indicate an individual's potential for metabolism of exogenous substances. Further, inherited genetic polymorphic markers, e.g., DNA-RFLPs at protooncogene loci (HRAS-1 and L-myc) have been examined in a case-control study of lung cancer. Data concerning mutations of protooncogenes (H-, K-, and N-RAS) and tumor suppressor genes (retinoblastoma and p53 genes) in various common cancers are providing evidence of multiple genetic lesions that occur during the multistage process of carcinogenesis.
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PMID:Biochemical and molecular epidemiology of cancer. 191 Jun 3

We studied 83 lung cancer patients and 129 controls for the EcoRI polymorphism of the L-myc gene. No association was found between the L-myc RFLP and increased risk of metastasis, either to lymph nodes or metastasis to other organs. There was no difference in survival time between the three different genotypes. The S-allele of the L-myc RFLP has been correlated to increased metastasis in lung cancer. We found no tendency towards a higher frequency of this allele in the cohort of patients with positive family history compared to the patients with no known first degree relatives with cancer. A higher frequency of the S-allele in the adenocarcinomas compared to other histological groups was found, although this difference was not statistically significant. No difference in the gene frequency of the L-myc RFLP was found between the lung cancer patients and the normal controls. These results are in contrast with a previous report. Possible explanations for the discrepancies are discussed.
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PMID:Studies of the L-myc DNA polymorphism and relation to metastasis in Norwegian lung cancer patients. 197 18

The L-myc DNA-restriction fragment length polymorphism, revealed by EcoRI, has been studied in both a lung cancer case-control framework and a cohort of 40 non-diseased unrelated individuals. No association was found between the L-myc allelic frequencies and disease status, tumor stage or lung cancer histology. A strong association was, however, observed between the L-myc allelic frequencies and ethnic origin (black or white) of the subjects. Among American whites the allelic distribution at the L-myc proto-oncogene locus was almost identical to that previously reported for Japanese subjects. Among the American black population there was a significantly higher frequency of the presence of the polymorphic EcoRI restriction site in the second intron of the L-myc proto-oncogene. These data emphasize the importance of conducting epidemiologic studies that control for ethnic factors and indicate that L-myc EcoRI allelotypes do not appear to be predictive of lung cancer risk or disease status in American blacks and whites.
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PMID:Restriction fragment length polymorphism analysis of the L-myc gene locus in a case-control study of lung cancer. 197 65

The development of human lung cancer may require multiple genetic deletions affecting a number of chromosomes, e.g., 1, 3, 11, 13, and 17. These genetic aberrations may induce the activation of proto-oncogenes (c-jun, ras, c-raf1) and the loss of tumor suppressor genes (p53). Some of the activated proto-oncogenes and tumor suppressor genes are more selectively expressed or absent in small-cell lung cancer (L-myc, c-myb, c-scr, Rb gene) or non-small-cell lung cancer (c-erbB-2, c-sis, c-fes). These genes may thus be of importance for selection of differentiation pathway. The c-myc oncogene is frequently amplified in small-cell lung cancer cell lines in a much higher frequency than in vivo. This indicates that c-myc seems to be related to tumor progression and a relatively late event in the lung cancer development. The uncontrolled production of multiple growth factors has been identified in human lung cancer cell lines. These factors can promote and inhibit the proliferation via paracrine and autocrine loops via specific receptors. The products from some of the activated proto-oncogenes (c-sis, c-erbB-2) are sequences homologous to a certain growth factor (PDGF) and a receptor (EGF) identified in lung cancer. The production and action of these growth factors may be of major importance for further activation of proto-oncogenes via intracellular signal transduction and specific oncogenic activation leading to further tumor progression.
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PMID:Gene amplification in human lung cancer. The myc family genes and other proto-oncogenes and growth factor genes. 217 59

The interactions of cytogenetic and molecular genetic changes in the pathogenesis and progression of lung cancer are complex. To the practicing pathologist, certain of these changes may prove useful as diagnostic or prognostic markers and may help in selecting patients for particular types of therapy. Changes such as 3p14-23 deletions, c-myc amplification, and L-myc RFLPs have already been reported to predict aggressive behavior in lung cancer. Future studies will clarify the application of these changes to the clinical care and treatment of patients with carcinoma of the lung.
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PMID:The cytogenetics and molecular genetics of lung cancer. Implications for pathologists. 220 63

The expression of myc-related genes (c-myc, N-myc, and L-myc) in small cell lung cancer (SCLC) was studied by RNA-RNA tissue in situ hybridization. The tissues investigated included cytospins of ten cell lines derived from patients with SCLC, four corresponding nude mouse xenografts from cell lines, and metastatic tumor tissue obtained by surgical biopsy and at autopsy. The probes were prepared as 35S labeled complementary RNA. The expression of each gene was demonstrated specifically by autoradiography in the cytoplasm of the neoplastic cell samples. The average levels of oncogene expression in each specimen corroborated previous data obtained by Northern blot assays. In addition, heterogeneity in gene expression from cell to cell in each sample was noted. This study represents the first attempt to demonstrate oncogene expression in lung cancer cell lines and tissues in situ, and confirms that the expression of these myc related genes can be seen in the primary tumor. The technique of RNA-RNA tissue in situ hybridization has great potential in answering fundamental questions of tumor cell heterogeneity and progression in SCLC. It should be useful in both prospective and retrospective studies.
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PMID:A study of myc-related gene expression in small cell lung cancer by in situ hybridization. 245 19


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