Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0043346 (xeroderma pigmentosum)
 2,924 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The purpose of the present study was to determine whether skin fibroblasts from individuals, either with an inherited predisposition to cancer or with genetic disorders usually associated with a high risk of cancer, can be oncogenically transformed in vitro by a tumor promoter alone. The effects of chronic and limited applications of 12-O-tetradecanoylphorbol-13-acetate (TPA) on several properties that are associated with transformation were examined using skin fibroblasts from individuals with polyposis coli, a familial cancer syndrome, xeroderma pigmentosum, Fanconi's anemia, and trisomy 21. The results of this study show that TPA treatment induces similar changes on cellular morphology, growth rate, saturation density, epidermal growth factor binding, and cytoskeleton in fibroblasts from both normal and genetically predisposed individuals. None of these cell lines, however, acquired anchorage-independent growth or unlimited growth potential in culture after chronic application of TPA. These observations suggest clearly that skin fibroblasts from individuals with either a genetic predisposition to or a high risk of cancer may not exist in a preneoplastic or "initiated" state susceptible to oncogenic transformation by TPA alone and that the mechanism of genetically determined cancer induction may be different from that of chemical carcinogenesis.
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PMID:Effects of 12-O-tetradecanoylphorbol-13-acetate on fibroblasts from individuals genetically predisposed to cancer. 621 97

A systematic review of the more than 2,000 genetic loci of man cataloged by McKusick indicated that approximately 7% may play a role in modulating the rates of development of various aspects of the senescent phenotype. Assuming an upper limit of about 100,000 loci in man, numerous alleles at approximately 7,000 loci could be contributing to characteristic patterns of aging in individual human beings. Point mutations or chromosomal aberrations involving such loci may result in various progeroid syndromes. These have been classified into two categories: segmental progeroid syndromes, which involve multiple aspects of the senescent phenotype, and unimodal progeroid syndromes, in which predominantly one aspect of the phenotype is involved. Two different examples of segmental progeroid syndromes were discussed: the Werner syndrome (an autosomal recessive) and the Down syndrome (trisomy 21). Examples of unimodal progeroid syndromes included familial hypercholesterolemia (accelerated atherogenesis), xeroderma pigmentosum (acceleration of skin aging, including age-related neoplasms), and certain forms of intestinal polyposis (acceleration of adenocarcinoma of the colon). It is remarkable and encouraging that the biochemical genetic basis of many progeroid syndromes, including all of those mentioned above, may be amenable to investigation with cultured mesenchymal somatic cells from individual subjects. For example, cells from patients with the Werner's syndrome have a striking limitation of their in vitro replicative life-spans and undergo extensive chromosomal rearrangements. These abnormalities are presumably related to an enzyme deficiency which, in principle, could be identified by biochemical studies of cultured cells.
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PMID:Syndromes of accelerated aging. 621 19

The potential of enhanced chromatid damage, observed after X-irradiation of G2 phase, has been used to detect individuals genetically predisposed to cancer, utilising fibroblast/lymphocytes from these patients as well as fibroblasts derived from human tumours. Fibroblasts and/or lymphocyte samples of two autosomal recessive syndromes (xeroderma pigmentosum (XP), Fanconi's anaemia (FA)) and one congenital or acquired disorder, aplastic anaemia (AA), were employed for the G2 radiosensitivity assay. In addition, we have estimated the frequencies of spontaneously occurring chromosomal aberrations as well as G2 radiosensitivity of eight samples of fibroblasts/fibroblast-like cells (two normal, two colorectal carcinoma, two Wilms' tumour, one retinoblastoma and one polyposis coli), and three samples of lymphocytes (two normal and one from a lymphoma patient). The results obtained indicate that there were no differences between fibroblast cells derived from patients or tumours, except FA patients, in the frequency of spontaneously occurring chromosomal aberrations when compared to normal cells. Following X-irradiation we did not observe any significantly increased G2 radiosensitivity in FA and XP cells. Lymphocytes from AA and lymphoma patients, and all tumour cell lines except retinoblastoma, responded with increased frequencies of aberrations following G2 X-irradiation in comparison to cells derived from normal individuals. In our hands, the G2 sensitivity assay could not always discriminate cells from cancer-prone individuals from those of controls.
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PMID:G2 radiosensitivity of cells derived from cancer-prone individuals. 789 7

Defective mismatch repair has recently been implicated as the major contributor towards the mutator phenotype observed in tumour cell lines derived from patients diagnosed with hereditary non-polyposis colon cancer (HNPCC). Cell lines from other cancer-prone syndromes, such as xeroderma pigmentosum, have been found to be defective in nucleotide excision repair of damaged bases. Some genetic complementation groups are defective specifically in transcription-coupled excision repair, although this type of repair defect has not been associated with cancer proneness. Mechanisms contributing to the high incidence of activating point mutations in oncogenes (such as H-ras codon 12) are not understood. It is possible that novel mechanisms of misrepair or misreplication occur at these sites in addition to the above DNA repair mechanisms. In this study, we have compared the rate of strand-directed mismatch repair of four mispairs (G:A, A:C, T:C and G:T) at the H-ras codon 12, middle G:C position. Our results indicate that, although this location is not a 'hot spot' for bacterial mismatch repair, it is a 'hot spot' for decreased repair of specific mismatched bases within NIH 3T3 cells. NIH 3T3, unlike Escherichia coli, have an extremely low repair rate of the G:A mispair (35%), as well as the A:C mispair (58%) at this location. NIH 3T3 also have a moderately low repair rate of the T:C mispair (80%) at the codon 12 location. Conversely, NIH 3T3 repair of G:T (100%) is comparable to E. coli repair (94%) of this mismatch. These results demonstrate that a mismatch containing an incorrect adenine on either strand at the H-ras codon 12 middle base pair location is most likely to undergo a mutational event in NIH 3T3 cells. Conversely, a mismatch containing an incorrect thymine in the transcribed strand is least likely to undergo a mutational event.
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PMID:Site- and strand-specific mismatch repair of human H-ras genomic DNA in a mammalian cell line. 923 Feb 73

Mechanisms of carcinogenesis through abnormalities of DNA repair genes are overviewed. Inactivation of DNA mismatch repair(MMR) gene(s) observed in tumors of hereditary non-polyposis colorectal cancer induces frameshift mutator mutation in MMR genes themselves, growth inhibitory genes and apoptosis inhibitory genes providing favorable genetic background for a malignant clone to be expanded. Deficiency of nucleotide excision repair that is usually employed for the removal of pyrimidine dimer formed by ultraviolet-irradiation in xeroderma pigmentosum (XP) causes hypersensitivity of the skin to sunlight as well as increased risk of skin cancer. Strand specificity and absence of hot spots for p53 tumor suppressor gene mutations was reported in ultraviolet induced skin cancers of XP model mice.
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PMID:[Carcinogenesis through abnormalities of DNA repair genes]. 1087 47

Cellular and humoral defence mechanisms are essential for the survival of individuals and species. Thus, DNA repair prevents mutations and cytotoxicity from DNA damage, thereby reducing the risks of inappropriate cell death, developmental defects, premature ageing and cancer. Similarly, antigen-dependent acquired immune responses prevent infections and also have a role in cancer prevention. DNA repair is highly complex and functions in an intricate network that also involves transcription, replication, cell cycle regulation, and the immune system. DNA damage is repaired by at least four major mechanisms, each requiring many different proteins. In addition there are "subpathways", and back-up mechanisms both within and between pathways. Various defects in DNA repair result in different forms of cancer, e.g. the rare syndrome Xeroderma pigmentosum and the more common diseases early-onset breast cancer and hereditary non-polyposis colon cancer. Surprisingly, recent research has revealed molecular interactions between the ancient DNA repair mechanisms and the much younger acquired immune system. Thus, the classical base excision enzyme uracil-DNA glycosylase encoded by the UNG gene is also involved in somatic hypermutation and class switch recombination, e.g. from IgM antibodies to IgG, yielding secreted high affinity antibodies. Mutations in both alleles of UNG result in a hyper-IgM syndrome with life-threatening infections. Furthermore, it has recently become clear that not only DNA, but also RNA and proteins are repaired. Thus, certain aberrant methylations in RNA are repaired by oxidative demethylation in one step restoring the normal base, and at least in a bacterial model system this increases survival several-fold after exposure to methylating agents. Proteins are repaired both at the peptide amino acid level and at the structural level. RNA and protein repair are likely to be important to prevent the formation of cytotoxic protein aggregates of the types known to cause neurodegenerative diseases e.g. Alzheimer's, Parkinson's and Huntington's diseases, and other diseases as well. In conclusion, recent research has demonstrated an unexpected complexity of cellular defence mechanisms that function in intricate networks, rather than as independent mechanisms. The new knowledge opens for interventions that are based on a deeper understanding of the mechanisms of defence.
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PMID:Novel aspects of macromolecular repair and relationship to human disease. 1498 56