Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Skin cancer is unique among human cancers in its etiology, accessibility and the volume of detailed knowledge now assembled concerning its molecular mechanisms of origin. The major carcinogenic agent for most skin cancers is well established as solar ultraviolet light. This is absorbed in DNA with the formation of UV-specific dipyrimidine photoproducts. These can be repaired by nucleotide excision repair or replicated by low fidelity class Y polymerases. Insufficient repair followed by errors in replication produce characteristic mutations in dipyrimidine sequences that may represent initiation events in carcinogenesis. Chronic exposure to UVB results in disruption of the epithelial structure and expansion of pre-malignant clones which undergo further genomic changes leading to full malignancy. Genetic diseases in DNA repair, xeroderma pigmentosum, Cockayne syndrome and trichothiodystrophy, show varied elevated symptoms of sun sensitivity involving skin cancers and other symptoms including neurological degeneration and developmental delays. In humans, only xeroderma pigmentosum shows high levels of cancer, but mouse strains, with any of the genes corresponding to these diseases knocked-out, show elevated skin carcinogenesis. The three major skin cancers exhibit characteristic molecular changes defined by certain genes and associated pathways. Squamous cell carcinoma involves mutations in the p53 gene; basal cell carcinoma involves mutations in the PATCHED gene, and melanoma in the p16 gene. The subsequent development of malignant tumors involves many additional genomic changes that have yet to be fully cataloged.
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PMID:UV damage, DNA repair and skin carcinogenesis. 1189 51

The MICA gene encodes for major histocompatibility complex class I chain-related proteins (MIC), which belong to a recently identified new family of nonclassical major histocompatibility complex molecules. The general structure of the MICA molecule resembles that of major histocompatibility complex class I molecules. MIC molecules are considered to be stress-induced antigens that are recognized by cytotoxic T cells and natural killer cells, which play an important role in the surveillance of transformed infected and damaged cells. Associations of major histocompatibility complex class I molecules with skin cancer have been described before. To evaluate the possible association of MICA gene polymorphism with the risk for nonmelanoma skin cancer we evaluated 153 cases with squamous cell carcinoma, 261 cases with basal cell carcinoma, 111 controls with malignant melanoma, and 247 controls without a history of skin cancer. Five distinct MICA alleles A4, A5, A6, A9, and A5.1 were studied. As the MICA 5.1 variant gene contains a four-nucleotide insertion that causes a stop codon in the trans membrane region, the resulting truncated MICA molecule does not reside on the cellular membrane. In the case of individuals who are homozygous for MICA 5.1 this results in cells that are naked for the MICA molecule. We therefore specifically addressed the possible association between MICA 5.1 homozygosity and skin cancer, as these individuals are expected to be at the highest risk for skin cancer if the MICA gene plays a role in skin carcinogenesis. Viral proteins may serve as antigens for recognition of skin cancer by the immune system. Human papillomavirus is the most likely candidate virus to be involved in the carcinogenesis of cutaneous squamous cell carcinoma. Hence, we also assessed the association between MICA polymorphism and squamous cell carcinoma in human-papillomavirus-positive and human-papillomavirus-negative individuals as identified by the presence of human papillomavirus DNA in hairs plucked from their eyebrows. Our analyses did not reveal any significant differences regarding the MICA allele frequencies between cases and controls. Also homozygotes and heterozygotes for the MICA 5.1 variant gene were not at an increased risk for skin cancer compared to individuals without this variant gene and infection with human papillomavirus did not materially influence these findings. The same group of cases and controls was large enough to show an association between melanocortin 1 receptor gene polymorphism and skin cancer and to reasonably exclude an association between p53 codon 72 polymorphism and skin cancer. Therefore, we conclude that an association between MICA gene polymorphism and nonmelanoma skin cancer is not likely.
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PMID:MICA gene polymorphism is not associated with an increased risk for skin cancer. 1191 17

The expression of bcl-2, bax and p53 protein was studied in the basal cell carcinoma with 32 patients by immunohistochemical method. The results showed that bcl-2 protein was positive in 26 patients (81.2%), bax protein was positive in 9 patients(28.1%), and p53 protein was positive in 13 patients (40.6%); there is a negative correlation between the expression of bcl-2 and bax protein(P < 0.05). These findings suggest that apoptosis is suppressed which might cause the production of basal cell carcinoma.
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PMID:[Expression of bcl-2, bax and p53 protein in the basal cell carcinoma]. 1193 85

Basal cell carcinoma (BCC) of the skin is the most common type of cancer in humans. Like squamous cell carcinomas, they are also believed to be ultraviolet (UV)-induced, but several data suggest that some differences might exist in the mechanisms of their UV induction. The originating cells may arise from interfollicular basal cells, hair follicles or sebaceous glands, thus from a deeper zone than the SCC ones, which probably means exposure to different doses or wavelengths of UV. The p53 gene and the patched gene (PTCH) are major targets of UV for BCC induction. Mutations in p53 are present in about 56% of human BCC, even small early lesions. The "UV signature" is observed in 65% of them. Mutations in the PTCH play also a major role in BCC development, being responsible for hereditary BCCs in Gorlin's syndrome, sporadic BCC, and BCCs isolated from xeroderma pigmentosum, although with a lower incidence of "UV signature". Smoothened-activating mutations and PTCH2 mutations are also involved in BCC formation. Transgenic mice overexpressing Smoothened or Sonic hedgehog in the skin spontaneously produce skin lesions resembling human BCCs, but contrary to findings in the hairless albino mouse and with SCC, no data on experimental UV induction of BCCs are available.
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PMID:Carcinogenesis of basal cell carcinomas: genetics and molecular mechanisms. 1196 27

Mutations of p53 and PTCH gene, two candidate tumor suppressor genes for basal cell carcinoma (BCC), were screened in 15 cases of sporadic BCCs that developed in sun-exposed skin region in a Korean population. p53 and PTCH mutations were detected at a frequency of 33 and 40%, respectively, and the mutations were predominantly UV-signature transition, C-->T transitions at dipyrimidine sites and CC-->TT tandem mutations. In both genes, the most common mutations were missense mutations resulting in amino acid substitution, which is different than the results from Caucasian BCCs where mutations are frequently predicted to make truncated or absent proteins. All mutations, except for one, occurred on the nontranscribed strand where is little efficient removal of UV-induced pyrimidine dimers relative to the transcribed strand. Loss of heterozygocity (LOH) of 9q22 for PTCH loci was found in eight of 15 informative cases of BCCs (53%), but none of the cases were informative for LOH of 17p13 for p53 loci. Not only do our data indicate the key role played by p53 and PTCH in the development of BCCs, these findings also suggest that UVB may significantly contribute to BCC tumorigenesis. Moreover, molecular epidemiology composed of incidence of p53 and PTCH mutations, difference in the type of mutation and repair bias of UV-induced DNA lesions might affect the distinct features of BCCs between different racial population.
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PMID:Mutations of the p53 and PTCH gene in basal cell carcinomas: UV mutation signature and strand bias. 1200 15

Immunocytochemical studies of the expression of PCNA, Ki67 and p53 protein have been done by different groups on sporadic keratocysts (OKCs) and OKCs associated with the naevoid basal cell carcinoma syndrome (NBCCS). These 'markers' have in common that they are all expressed in actively proliferating cells, particularly in neoplasms. The findings were compared with their expression in dentigerous and radicular cysts. While there was some variability in the reported results, probably because of technical inconsistencies and the use of different antibodies, a definite trend emerged. In general PCNA, Ki67 and p53 positivity occurred more frequently and more intensely in the OKCs, and in the syndrome-related more than the solitary, compared with the other cyst types. In the OKCs the positivity was expressed mostly in the suprabasal layers of epithelium whereas in the other cysts types it was mainly in the basal layer that positivity was observed. Other studies showed that the gene for the NBCCS (PTCH), a tumour suppressor gene, mapped to chromosome 9q22.3. PTCH gene mutation has been shown to be an important step in the pathogenesis of the OKC and was thought to have a role in the development of the sporadic as well as the syndrome-related OKCs. The 'two-hits' hypothesis was invoked in support of the view that syndrome-related basal cell carcinomas (BCCs) and OKCs probably arise from precursor cells that contain an inherited 'first hit'. Only a single mutation was then required in the somatic cell to cause homozygous inactivation and neoplastic progression. Sporadic OKCs might arise from susceptible cells in which two somatic mutations or 'hits' have occurred, one of which manifests as allelic loss. The loss of tumour suppressor genes supports the view that the OKC is a benign neoplasm.
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PMID:The aggressive nature of the odontogenic keratocyst: is it a benign cystic neoplasm? Part 2. Proliferation and genetic studies. 1207 94

Basal cell carcinoma (BCC) is a subtype of nonmelanoma skin cancer (NMSC), a potentially fatal disease linked to overexposure to the sun during childhood. BCC has been associated with UV-induced mutations of the PTC and p53 tumor suppressor genes, and to polymorphisms in the melanocortin-1 receptor and XPD genes. Mortality rates due to BCC are low, but its increasing incidence and prolonged morbidity means the disease is costly to treat. Early recognition and effective treatment are therefore important, to reduce the incidence of BCC and lighten the economic burden of its management. This paper reviews current treatments for BCC, including excision and curettage, electrodessication, surgery, cryosurgery, radiotherapy, and treatment with 5-fluorouracil and intralesional/perilesional cytokines. It also deals with two new treatment modalities, photodynamic therapy and imiquimod 5% cream, an immune response modifier that effectively resolves BCC lesions.
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PMID:New treatment modalities for basal cell carcinoma. 1207 22

Upregulation of p53 protein induces either growth arrest or apoptosis in response to cellular injury This is signaled from a highly conserved p53 domain between codons 64 and 92, where a functional polymorphism results in either a proline (p53-72P) or an arginine (p53-72R) at codon 72. Preliminary studies suggest that p53-72R may be a risk factor for cervical cancer and, consistent with this, preferential mutation and retention of the p53-72R allele has also been demonstrated in other cancers of squamous cell origin. Here we examine the relationship between allelic forms of p53 and nonmelanoma skin cancer, by determining the correlation with susceptibility to sunburn, which is a known risk factor, and then by p53 sequence analysis of a large series of tumors. We found a significant positive association between p53-72R and susceptibility to sunburn, as assessed by skin phototype and minimal erythemal dose following solar-simulated radiation (p = 0.0001 for trend). We also found a significant association between p53-72R homozygosity and nonmelanoma skin cancer in renal transplant recipients (basal cell carcinoma, p < 0.01; squamous cell carcinoma, p < 0.05) but not in immunocompetent patients compared with skin type matched controls. p53 sequence data revealed mutations in 30 of 70 (42.9%) nonmelanoma skin cancers, 28 (93%) of which were in the p53-72R allele. Loss of heterozygosity occurred more frequently in p53-72RP than in p53-72RR tumors (p = 0.0001) with preferential loss of p53-72P in heterozygotes (p = 0.016), irrespective of the mutant status of the concomitant allele. Together these data infer functional differences between polymorphic forms of p53 that are likely to be relevant to skin carcinogenesis.
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PMID:Relationship between p53 codon 72 polymorphism and susceptibility to sunburn and skin cancer. 1514 Feb 41

Xeroderma pigmentosum is an inheritable autosomal recessive DNA repair deficient syndrome characterized by a high predisposition to skin cancers. An elevated proportion of tumors from xeroderma pigmentosum patients harbor ultraviolet-induced mutations (CC:GG > TT:AA tandem transitions) of the p53 and/or the INK4a-ARF genes. Here, we report the clinical and molecular features of a 12 y old xeroderma pigmentosum patient who, in addition to severe cutaneous clinical symptoms, also had three unusual tumors, a mediastinal lymphoblastic lymphoma, an atypical fibroxanthoma, and an epithelioid hemangioma. Single strand conformation polymorphism and sequencing analysis of the p53 and INK4a-ARF genes were carried out in DNA from normal skin and different tumors (four actinic keratosis, two microinvasive squamous cell carcinomas, one basal cell carcinoma, and one atypical fibroxanthoma) from the patient. After characterization of the xeroderma pigmentosum C complementation group, we found unexpectedly that this patient also carried a germline mutation of the INK4a-ARF locus affecting the p16INK4A reading frame. Three different somatic mutations that all harbor the signature of ultraviolet light (two of p16INK4A and one of p53) were also detected in the basal cell carcinoma. We hypothesize that the germline mutation of p16INK4A, in association with the nucleotide excision repair defect, could explain the patient's unusual phenotype. Furthermore, this study confirms that concomitant somatic mutations of INK4a-ARF and p53 occur in some xeroderma pigmentosum associated tumors, and seem to accumulate during tumor progression rather than the initiation step.
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PMID:Germline and somatic mutations of the INK4a-ARF gene in a xeroderma pigmentosum group C patient. 1248 39

The ideal classification of basal cell carcinoma (BCC) should be able to identify subtypes which correlate with clinical behaviour and treatment requirements. Unfortunately, however, such a classification has yet to be defined. In the interim, the currently most favoured classification is one based predominantly on histological growth pattern. This classification contributes to the useful concept of low- and high-risk histological subtypes of BCC. The latter are characterized by an increased probability of subclinical extension and/or incomplete excision and/or aggressive local invasive behaviour and/or local recurrence. The Royal College of Pathologists has published a minimum dataset for the histopathological reporting of BCC and this has been written to be compatible with the British Association of Dermatologists' management guidelines. Growth patterns to be reported include nodular, superficial, infiltrative/morphoeic and micronodular types, together with differentiation when of severely atypical or malignant squamous type (basosquamous carcinoma). Deep and peripheral excision margins will be reported to be either involved or clear. The latter will include a comment of a clearance of less than 1 mm for close margins and a measured distance in whole millimetres for other excisions. Clinical assessment and histology remain the 'gold standard' for evaluating BCC and cancers in general. However, in the postgenomic era emphasis is changing from the gathering and archiving of genomic data to its analysis and use in guiding clinical practice. In this context, a current goal is to define cancer phenotype in terms of molecular abnormalities and use this as a new gold standard. One way to assess whether this goal is being achieved for BCC is to determine whether our knowledge of its molecular pathology has any relevance to the minimum dataset for histological reporting. Knowledge of BCC molecular pathology has been fuelled by the recent discovery that deregulation of the Hedgehog (Hh) signalling pathway, a key player in embryonic patterning, appears to be fundamental to tumour growth. But despite accrual of a large amount of data concerning Hh pathway molecular alterations in neoplasia, little is known about the functional consequences of these changes in BCC, how they lead to tumour development, or how they relate to non-Hh pathway alterations such as TP53 mutation. Recent work suggests that the cellular localization of beta-catenin gives a degree of credence to the growth pattern classification of BCC. Furthermore, it is possible that beta-catenin may have a pathogenetic role in the invasive behaviour of BCC. This review draws on current evidence to discuss these issues and assess whether they are relevant to the minimum dataset.
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PMID:Basal cell carcinoma: a dermatopathological and molecular biological update. 1258 68


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