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Kraft S, Granter SR. Molecular pathology of skin neoplasms of the head and neck. Arch Pathol Lab Med 2014; 138:759-87. [PMID: 24878016 DOI: 10.5858/arpa.2013-0157-ra] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
CONTEXT Skin neoplasms include the most common malignancies affecting humans. Many show an ultraviolet (UV)-induced pathogenesis and often affect the head and neck region. OBJECTIVE To review literature on cutaneous neoplasms that show a predilection for the head and neck region and that are associated with molecular alterations. DATA SOURCES Literature review. CONCLUSIONS Common nonmelanoma skin cancers, such as basal and squamous cell carcinomas, show a UV-induced pathogenesis. Basal cell carcinomas are characterized by molecular alterations of the Hedgehog pathway, affecting patched and smoothened genes. While squamous cell carcinomas show UV-induced mutations in several genes, driver mutations are only beginning to be identified. In addition, certain adnexal neoplasms also predominantly affect the head and neck region and show interesting, recently discovered molecular abnormalities, or are associated with hereditary conditions whose molecular genetic pathogenesis is well understood. Furthermore, recent advances have led to an increased understanding of the molecular pathogenesis of melanoma. Certain melanoma subtypes, such as lentigo maligna melanoma and desmoplastic melanoma, which are more often seen on the chronically sun-damaged skin of the head and neck, show differences in their molecular signature when compared to the other more common subtypes, such as superficial spreading melanoma, which are more prone to occur at sites with acute intermittent sun damage. In summary, molecular alterations in cutaneous neoplasms of the head and neck are often related to UV exposure. Their molecular footprint often reflects the histologic tumor type, and familiarity with these changes will be increasingly necessary for diagnostic and therapeutic considerations.
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Affiliation(s)
- Stefan Kraft
- From the Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (Dr Kraft); and the Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts (Dr Granter)
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Abstract
INTRODUCTION Actinic keratosis (AK) represents the initial intraepidermal manifestation of abnormal keratinocyte proliferation, with the potential of progression to squamous cell carcinoma (SCC). Few visible AKs lead to the use of lesion-directed treatments, including ablative and/or surgical procedures. Multiple and/or the suspicion of subclinical (non-visible) AKs lead to the use of field-directed therapies, including topical and ablative treatments. Predicting which AK will progress to SCC is difficult, and so all are treated. The goals of treatment are to eliminate visible AKs and to treat subclinical (non-visible) AKs, minimizing their risk of progression to invasive SCC, while pursuing good cosmesis. AREAS COVERED This review discusses the prevention of AKs (such as ultraviolet light avoidance, sunscreen use, protective clothing, and frequent self-examinations, in addition to chemoprevention with retinoids, eflornithine, silymarin, and others). It also covers lesion-directed treatments (e.g., cryotherapy, electrodessication and curettage, and surgery). Field-directed treatments are also mentioned (including laser resurfacing, dermabrasion, chemical peels, topical immunomodulators (imiquimod and diclofenac), topical chemotherapeutic agents (5-fluorouracil and retinoids), and photodynamic therapy). Finally, newer and investigational treatments are discussed (including ingenol mebutate). EXPERT OPINION There is no panacea in the treatment of AKs. The current best approach is the sequential treatment with a lesion-directed and a field-directed therapy. Several combinations seem to work well; they just need to be selected based on the evidence and adjusted to patient needs, preferences and dermatologist expertise.
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Affiliation(s)
- Brian Berman
- Center for Clinical and Cosmetic Research, Skin and Cancer Associates, Aventura, FL 33180, USA.
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Berman B, Amini S, Valins W, Block S. Pharmacotherapy of actinic keratosis. Expert Opin Pharmacother 2009; 10:3015-31. [DOI: 10.1517/14656560903382622] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Ohnuma-Ishikawa K, Morio T, Yamada T, Sugawara Y, Ono M, Nagasawa M, Yasuda A, Morimoto C, Ohnuma K, Dang NH, Hosoi H, Verdin E, Mizutani S. Knockdown of XAB2 Enhances All-Trans Retinoic Acid–Induced Cellular Differentiation in All-Trans Retinoic Acid–Sensitive and –Resistant Cancer Cells. Cancer Res 2007; 67:1019-29. [PMID: 17283134 DOI: 10.1158/0008-5472.can-06-1638] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Xeroderma pigmentosum group A (XPA)-binding protein 2 (XAB2) is composed of 855 amino acids, contains 15 tetratricopeptide repeat motifs, and associates with Cockayne syndrome group A and B proteins and RNA polymerase II, as well as XPA. In vitro and in vivo studies showed that XAB2 is involved in pre-mRNA splicing, transcription, and transcription-coupled DNA repair, leading to preimplantation lethality, and is essential for mouse embryogenesis. Retinoids are effective for the treatment of preneoplastic diseases including xeroderma pigmentosum and other dermatologic diseases such as photoaging. We therefore focused on defining the effect of XAB2 on cellular differentiation in the presence of ATRA treatment. In the present study, we showed that overexpression of XAB2 inhibited ATRA-induced cellular differentiation in human rhabdomyosarcoma cell line, and that knockdown of XAB2 by small interfering RNA (siRNA) increased ATRA-sensitive cellular differentiation in the human promyelocytic leukemia cell line HL60 at both physiologic (10(-9)-10(-8) mol/L) and therapeutic (10(-7) mol/L) concentrations of ATRA. Moreover, we found that XAB2 was associated with retinoic acid receptor alpha (RARalpha) and histone deacetylase 3 in the nuclei. Finally, using siRNA against XAB2, we showed that the ATRA-resistant neuroblastoma cell line IMR-32 underwent cellular differentiation induced by ATRA at a therapeutic concentration (10(-6) mol/L). These results strongly suggest that XAB2 is a component of the RAR corepressor complex with an inhibitory effect on ATRA-induced cellular differentiation and that XAB2 plays a role in ATRA-mediated cellular differentiation as an important aspect of cancer therapy.
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Affiliation(s)
- Kumiko Ohnuma-Ishikawa
- Department of Pediatrics, Graduate Medical School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 11308519, Japan
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Rosón E, García-Doval I, de la Torre C, Feal C, Cruces M. [De Sanctis-Cacchione syndrome]. ACTAS DERMO-SIFILIOGRAFICAS 2006; 96:586-8. [PMID: 16476302 DOI: 10.1016/s0001-7310(05)73140-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
We present a male patient with photosensitivity since the earliest months of his life, and pigmented macules in exposed areas, some showing clinical atypia, which increased in number over time. Molecular biology studies detected an alteration in DNA repair ability, so xeroderma pigmentosum was diagnosed. Shortly after birth, low weight, microcephaly and psychomotor retardation had been observed, but the cause was not established. The patient progressively showed neurological disorders that included perceptive deafness, hyporeflexia and areflexia, as well as choreoathetotic movements. Therefore, we felt that the patient's symptoms fit De Sanctis-Cacchione syndrome.
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Affiliation(s)
- Elena Rosón
- Servicio de Dermatología, Hospital Provincial, Complejo Hospitalario de Pontevedra, Spain.
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6
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Parris GE. The cell clone ecology hypothesis and the cell fusion model of cancer progression and metastasis: History and experimental support. Med Hypotheses 2006; 66:76-83. [PMID: 16169667 DOI: 10.1016/j.mehy.2005.08.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2005] [Accepted: 08/04/2005] [Indexed: 11/17/2022]
Abstract
The two-stage initiation-progression model of cancer is widely accepted. Although mutations explain initiation of neoplasia, the assumption that mutations are responsible for progression of neoplasia to cancer appears to have little experimental support. The "cell clone ecology hypothesis" explains why neoplasia evolve and the "cell fusion model of cancer progression and metastasis" describes how they evolve into clinically significant tumors. A brief history of important concepts and experiments is provided. Clinically significant cancers are effectively new parasite species that live, expand and evolve within the host. It is hypothesized that survival and fate of the parasite clones called "cancer" are governed by the principles of ecology. It is argued that while mutations or aneuploidy (asexual reproduction) can result in transient/self-limiting neoplasia, neither of these asexual modes of forming new karyotypes can maintain the ecologically fit parasites that develop into clinically significant cancer. Mutations and/or unstable genomes (aneuploidy) progressively degrade cell lines and if only these mechanisms were at work, neoplasia would spontaneously become extinct or benign (enfeebled) before reaching clinical significance (an example of "Muller's ratchet"). In the cell fusion model of (clinically significant) cancer progression and metastasis, cell-cell fusion is the essential element allowing normal cells or (transient) neoplasia to evolve into clinically significant cancers. Cell-cell fusion is required for producing and sustaining clinically significant cancer because it provides a sex-like mode of reproduction essential for an ecologically fit parasite organism. Cell-cell fusion provides the opportunity needed for tumors to rejuvenate cell lines containing abnormal genomes and rapidly evolve to acquire dramatically aggressive traits such as metastasis. Indeed, metastasis appears to require cell-cell fusion. Cell-cell fusion also partially overcomes erosion of teleomeres during clone expansion and allows the essential elements of a tumorigenic genome to hide from chemotherapy as recessive traits in cells with normal phenotypes and re-emerge (by cell-cell fusion) as a new cancer after the phenotypically cancerous cells have been eradicated by classical chemotherapy. Eradication of the cancer parasite cannot be routinely achieved by classical toxic chemotherapy alone or even by chemotherapy augmented with techniques needed to overcome anti-apoptotic traits of cancer cells. Direct chemical intervention against cell-cell fusion concurrent with classical toxic chemotherapy holds a promise of preventing re-lapse of the disease. Intervention against cell-cell fusion may also directly suppress metastasis based on the model presented here. The paper also summarizes work on the cell surface glycoprotein CD44 that implicates it as a key element in cell-cell fusion and hence cancer.
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Bernerd F, Asselineau D, Vioux C, Chevallier-Lagente O, Bouadjar B, Sarasin A, Magnaldo T. Clues to epidermal cancer proneness revealed by reconstruction of DNA repair-deficient xeroderma pigmentosum skin in vitro. Proc Natl Acad Sci U S A 2001; 98:7817-22. [PMID: 11438733 PMCID: PMC35425 DOI: 10.1073/pnas.141221998] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Sun exposure has been clearly implicated in premature skin aging and neoplastic development. These features are exacerbated in patients with xeroderma pigmentosum (XP), a hereditary disease, the biochemical hallmark of which is a severe deficiency in the nucleotide excision repair of UV-induced DNA lesions. To develop an organotypic model of DNA repair deficiency, we have cultured several strains of primary XP keratinocytes and XP fibroblasts from skin biopsies of XP patients. XP skin comprising both a full-thickness epidermis and a dermal equivalent was successfully reconstructed in vitro. Satisfactory features of stratification were obtained, but the expression of epidermal differentiation products, such as keratin K10 and loricrin, was delayed and reduced. In addition, the proliferation of XP keratinocytes was more rapid than that of normal keratinocytes. Moreover, increased deposition of cell attachment proteins, alpha-6 and beta-1 integrins, was observed in the basement membrane zone, and beta-1 integrin subunit, the expression of which is normally confined to basal keratinocytes, extended into several suprabasal cell layers. Most strikingly, the in vitro reconstructed XP skin displayed numerous proliferative epidermal invasions within dermal equivalents. Epidermal invasion and higher proliferation rate are reminiscent of early steps of neoplasia. Compared with normal skin, the DNA repair deficiency of in vitro reconstructed XP skin was documented by long-lasting persistence of UVB-induced DNA damage in all epidermal layers, including the basal layer from which carcinoma develops. The availability of in vitro reconstructed XP skin provides opportunities for research in the fields of photoaging, photocarcinogenesis, and tissue therapy.
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Affiliation(s)
- F Bernerd
- L'Oreal, Life Sciences Advanced Research, Centre C. Zviak, 90, Rue du Général Roguet, 92583 Clichy, France
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Isoherranen K, Westermarck J, Kähäri VM, Jansén C, Punnonen K. Differential regulation of the AP-1 family members by UV irradiation in vitro and in vivo. Cell Signal 1998; 10:191-5. [PMID: 9607142 DOI: 10.1016/s0898-6568(97)00100-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We have examined the effect of UVB and solar-simulated irradiation on the expression of the AP-1 family of transcription factors and the cytokine IL-6 both in cell cultures and in human skin in vivo. UVB irradiation potently induced c-jun, junB and c-fos mRNA levels in vitro in HaCaT cells. IL-6 mRNA was induced in response to UVB irradiation 2-3 h later than c-jun, junB and c-fos mRNAs. In human skin in vivo, solar-simulated irradiation induced transiently junB expression. Genistein, a tyrosine kinase inhibitor, augmented the induction of c-jun and junB by UVB irradiation in HaCaT cells. The results of this study provide evidence that in addition to c-jun and c-fos, junB is also an essential component of the human UV-response. This study also suggests that UVB irradiation regulates the AP-1 family by several mechanisms and that the signalling mechanisms of UVB irradiation are considerably different from the ones used by UVC irradiation.
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Affiliation(s)
- K Isoherranen
- Department of Clinical Chemistry, University of Turku, Finland.
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Abstract
Actinic keratoses are extremely common premalignant keratinocytic neoplastic lesions that develop primarily in fair-complexioned individuals during midlife or beyond. Genetic, occupational and other environmental factors predispose to the development of these lesions. Without treatment, a significant number may progress to fully developed neoplasms, especially squamous cell carcinoma, over a period of 20 to 50 years. The multistep theory of carcinogenesis is helpful in understanding the pathogenesis and progression of this important and highly prevalent lesion.
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Affiliation(s)
- J W Barnaby
- Division of Dermatopathology, University of Texas Southwestern Medical Center, Dallas, USA
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Green MH. Influence of environmental and genetic factors on variation in human response to DNA damaging agents. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 1996; 2:151-155. [PMID: 21781718 DOI: 10.1016/s1382-6689(96)00046-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Exogenous DNA damaging agents must be considered in the context of endogenous reactive species which have the potential to damage DNA. Although a no-effect level for a DNA-damaging compound may not exist, it may be feasible to define a level where reducing exposure to the compound is no longer the most effective way of reducing human risk. Modifying environmental factors which affect human response to damage may be the better strategy. Although a number of rare human syndromes are associated with a reduced ability to repair DNA damage, it is not clear how wide is the range of genetic variation in repair capacity among normal individuals. Studies with DNA repair-deficient human syndromes indicate that processes other than mutation and DNA repair must be involved in the development of cancer, and these processes may represent new sources of variation in human response to genotoxic agents.
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Abstract
Premalignant keratinocytic keratoses are common, especially in pale-complected persons in whom they appear most often as an actinic keratosis. Although the actinic keratosis has a very low malignant potential, arsenic, tar, thermal, scar, reactional, and radiation keratoses may be more clinically aggressive. This article discusses these premalignant keratinocytic neoplasms.
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Affiliation(s)
- R A Schwartz
- Dermatology and Pathology, UMDNJ-New Jersey Medical School, Newark 07103-2714, USA
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Punnonen K, Lehtola K, Autio P, Kiistala U, Ahotupa M. Chronic UVB irradiation induces superoxide dismutase activity in human epidermis in vivo. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 1995; 30:43-8. [PMID: 8558362 DOI: 10.1016/1011-1344(95)07131-k] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In order to study the effects of repeated UVB exposures on the epidermal antioxidant defence system, we obtained epidermis samples from male volunteers who were exposed to chronic UVB irradiation. Chronic UVB irradiation was shown to be accompanied by induction of epidermal superoxide dismutase (SOD) activity in vivo, while the activities of the other antioxidant enzymes were not significantly changed. The repeated exposure of the epidermis to UVB irradiation was not accompanied by accumulation of products of lipid peroxidation reactions. As superoxide dismutase is of major importance in scavenging the reactive oxygen species, the UVB-induced changes in SOD activity might provide the epidermis a way of defending itself against the effects of chronic UVB irradiation.
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Affiliation(s)
- K Punnonen
- Department of Clinical Chemistry, University Central Hospital of Turku, Finland
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Abstract
Non-melanocytic skin cancer has long been regarded as one of the harmful effects of solar ultraviolet (UV) radiation on human health. In this review, we examine epidemiologic evidence linking sun exposure and skin cancer coming from both descriptive studies in populations and analytical studies involving estimates of exposure in individuals. Particular attention is given to the quality of the published data. The epidemiologic evidence that sun exposure causes skin cancer is mainly indirect. Incidence or mortality is inversely related to latitude in populations of mainly European origin (e.g., the United States, Australia), and is higher in people born in Australia (high ambient solar radiation) than in migrants to Australia from the United Kingdom (lower ambient radiation). Skin cancer occurs mainly at sun-exposed body sites and in people who are sensitive to the sun; a reduced capacity to repair UV-induced DNA damage appears to increase the risk. The direct evidence linking sun exposure and skin cancer is weaker with few well-conducted studies of sun exposure in individuals. Mostly, studies of total sun exposure have not found statistically significant positive associations; those that did, had not adjusted for potential confounding by age and gender and thus their interpretation is limited. Studies of occupational sun exposure had relative risks not greater than 2.0; recreational exposure has been little studied. Other measurements, less direct but potentially less prone to measurement error, are sunburn (not evidently associated with skin cancer risk) and indicators of benign cutaneous sun-damage (strongly associated but lacking empirical evidence that sun exposure is their main cause). Many questions remain about the relationship between sun exposure and skin cancer.
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Affiliation(s)
- A Kricker
- International Agency for Research on Cancer, Lyon, France
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15
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Mariani E, Facchini A, Honorati MC, Lalli E, Berardesca E, Ghetti P, Marinoni S, Nuzzo F, Astaldi Ricotti GC, Stefanini M. Immune defects in families and patients with xeroderma pigmentosum and trichothiodystrophy. Clin Exp Immunol 1992; 88:376-82. [PMID: 1535035 PMCID: PMC1554504 DOI: 10.1111/j.1365-2249.1992.tb06457.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Xeroderma pigmentosum (XP) is a rare autosomal recessive disease characterized by photosensitivity, a high incidence of cancer in sun-exposed portions of the skin and a reduced capacity to repair the u.v.-induced DNA damage. One of the XP mutations (XP-D) has also been identified in patients affected by trichothiodystrophy (TTD), a rare autosomal recessive disease characterized by brittle hair, mental and physical retardation, peculiar face and ichthyosis. However, in these patients there is no evidence of increased skin tumour incidence. Since an impairment of cell-mediated immunity has been proposed as a co-factor in the cancer proneness of XP patients, we investigated the involvement of immune defect(s) in five XP patients, five TTD patients, their parents, and 24 TTD relatives. We evaluated the phenotype of circulating lymphocytes, natural killer (NK) cell lytic activity, target cell binding of NK cells at single cell level and the effect of interferons (IFN) alpha and beta on NK cell activity. The relative proportion of CD3+ and CD4+ circulating lymphocytes was reduced in XP but not in TTD patients. NK cell lytic activity was decreased in XP patients and their mothers, but their fathers showed normal lytic activity. NK activity varied among TTD families: four out of five patients and their relatives presented low NK cell activity, and one family was normal. In TTD family members, NK activity increased after incubation with IFN-alpha or IFN-beta, but never reached normal values. In contrast, in XP patients and their mothers, the defect was almost completely corrected after in vitro incubation with IFN-alpha or IFN-beta. Our study indicates impaired NK lytic activity in the majority of TTD and XP patients and that this defect is present also in members of their families. In addition, XP patients present a low number of circulating T cells. These multiple abnormalities, together with DNA repair defects, could be related to the increased cancer risk in XP patients.
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MESH Headings
- Abnormalities, Multiple/genetics
- Abnormalities, Multiple/immunology
- Adolescent
- Adult
- Antigens, CD/analysis
- Antigens, Differentiation, T-Lymphocyte/analysis
- CD3 Complex
- CD4 Antigens/analysis
- CD8 Antigens/analysis
- Child
- Child, Preschool
- Cytotoxicity, Immunologic/drug effects
- Facial Expression
- Female
- HLA-DR Antigens/analysis
- Hair/abnormalities
- Humans
- Immunity, Cellular
- Immunophenotyping
- Interferon alpha-2
- Interferon-alpha/pharmacology
- Interferon-beta/pharmacology
- Killer Cells, Natural/immunology
- Lymphocytes/immunology
- Male
- Receptors, Antigen, T-Cell/analysis
- Recombinant Proteins
- Xeroderma Pigmentosum/immunology
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Affiliation(s)
- E Mariani
- Laboratorio di Immunologia e Genetica, Istituto di Ricerca Codivilla Putti, I.O.R., Bologna, Italy
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Stefanini M, Giliani S, Nardo T, Marinoni S, Nazzaro V, Rizzo R, Trevisan G. DNA repair investigations in nine Italian patients affected by trichothiodystrophy. Mutat Res 1992; 273:119-25. [PMID: 1372095 DOI: 10.1016/0921-8777(92)90073-c] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Trichothiodystrophy (TTD) is a rare autosomal recessive disorder characterized by brittle hair, mental and growth retardation, peculiar face, ichthyosis, and in 20% of the reported cases photosensitivity. Cellular photosensitivity due to the same genetic defect present in xeroderma pigmentosum group D (XP-D) has been described in several patients. Nine patients with clinical symptoms diagnostic for TTD have been identified in Italy to date. We report the results of DNA repair investigations performed in cultured fibroblasts from these patients and 8 TTD parents. Survival, DNA repair synthesis and RNA synthesis following UV irradiation were all normal in the 8 TTD heterozygous cell strains. Among the 9 TTD-affected individuals, normal cellular UV sensitivity was observed in the 2 patients without signs of clinical photosensitivity. In contrast, the other 7 TTD cell strains showed a notable reduction in UV-induced DNA repair synthesis (UDS) levels, ranging between 40% and 5-15% of normal values. Complementation analysis indicated that in the repair-deficient TTD cell strains the genetic defect is the same as that present in XP-D cells. The biochemical heterogeneity of the XP-D defect in TTD patients characterized by different degrees of defective UDS results in different patterns of response to the killing effect of UV light in non-proliferating cells.
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Affiliation(s)
- M Stefanini
- Istituto di Genetica Biochimica ed Evoluzionistica C.N.R., Pavia, Italy
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17
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Lambert WC, Lambert MW. Co-recessive inheritance: A model for DNA repair and other surveillance genes in higher eukaryotes. ACTA ACUST UNITED AC 1992; 273:179-92. [PMID: 1372101 DOI: 10.1016/0921-8777(92)90079-i] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The co-recessive inheritance hypothesis proposes that certain recessively inherited diseases require homozygosity and/or hemizygosity for defective alleles at more than one locus simultaneously for the trait to be expressed. Although this hypothesis was originally proposed in the context of defective alleles for genes coding for DNA-repair functions, it need not be limited to this context, and genetic selection pressure may favor this model for genes involved in surveillance of any type. The co-recessive inheritance hypothesis also predicts extremely high carrier frequencies, likely affecting much of the general population, for defective alleles associated with these rare recessive diseases. The model predicts much lower rates of consanguinity between the parents of affected individuals than autosomal recessive inheritance, allowing it to be tested epidemiologically, and recent data suggest that the hypothesis may be valid for some cases of ataxia telangiectasia and xeroderma pigmentosum. The model provides possible explanations for a number of otherwise puzzling findings in several diseases associated with defective DNA repair.
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Affiliation(s)
- W C Lambert
- Department of Laboratory Medicine and Pathology, UMD-New Jersey Medical School, Newark 07103
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Abstract
'Ageing is a multistep, multifaceted, time-dependent phenomenon characterized by the decreased ability of a system to respond to exogenous and endogenous stress from either physical, chemical or biologic agents'. Cutaneous ageing provides a visible model of the interaction between endogenous (intrinsic) factors and exogenous (extrinsic) factors. In skin, the principal extrinsic-factor is ultraviolet light (UV) which is responsible for the constellation of changes termed photoageing. In recent years, much interest has been directed towards defining the ageing processes in skin and excellent comprehensive reviews have been compiled. This review aims to highlight several areas of developing knowledge, and focuses on the potential importance of environmental changes as they influence skin ageing and carcinogenesis. Repeated reference to the effects of UV on the skin are inevitable in any review of skin ageing and this is scarcely surprising as the skin contains many cells as well as subcellular and extracellular chromophores which are capable of absorbing energy within the UV spectrum. Cellular chromophores include among others keratinocytes, melanocytes, Langerhans cells, dermal fibroblasts and mast cells. Subcellular chromophores include keratin, melanin, collagen, elastin and a number of proteins, lipids and steroids (such as vitamin D). Urocanic acid, a photoisomerization product of the amino-acid histidine, may provide some limited photoprotection and some believe it to be important in UV induced immunosuppression. Understanding events at the molecular and biochemical level has unfortunately not been paralleled by clinical advances and the common, troublesome skin-problems of old age such as cancer, xerosis and pruritus remain a major cause of morbidity and yet are poorly explained.
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Affiliation(s)
- K L Dalziel
- Department of Dermatology, University Hospital, Queen's Medical Centre, Nottingham, UK
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