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)

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

Altered sonic hedgehog (SHH) signaling is crucial in the development of basal cell carcinomas (BCC), the most common human cancer. Mutations in SHH signal transducers, PATCHED and SMOOTHENED, have already been identified, but SHH mutations are extremely rare; only 1 was detected in 74 sporadic BCCs. We present data showing unique SHH mutations in BCCs from repair-deficient, skin cancer-prone xeroderma pigmentosum (XP) patients, which are characterized by high levels of UV-specific mutations in key genes involved in skin carcinogenesis, including PATCHED and SMOOTHENED. Thus, 6 UV-specific SHH mutations were detected in 5 of 33 XP BCCs. These missense SHH alterations are not activating mutations for its postulated proto-oncogene function, as the mutant SHH proteins do not show transforming activity and induce differentiation or stimulate proliferation to the same level as the wild-type protein. Structural modeling studies of the 4 proteins altered at the surface residues, G57S, G64K, D147N, and R155C, show that they do not effect the protein conformation. Interestingly, they are all located on one face of the compact SHH protein suggesting that they may have altered affinity for different partners, which may be important in altering other functions. Additional functional analysis of the SHH mutations found in vivo in XP BCCs will help shed light on the role of SHH in skin carcinogenesis. In conclusion, we report for the first time, significant levels of SHH mutations found only in XP BCCs and none in squamous cell carcinomas, indicating their importance in the specific development of BCCs.
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PMID:Functional analysis of novel sonic hedgehog gene mutations identified in basal cell carcinomas from xeroderma pigmentosum patients. 1515 Jan 12

The development of basal cell carcinoma, the commonest human cancer in fair skinned populations, is clearly associated with constitutive activation of sonic hedgehog signaling. Insight into the genesis of BCC came from the identification of germline mutations of the tumor suppressor gene, PATCHED, a key regulatory component of hedgehog signaling in the nevoid basal cell carcinoma syndrome. Analysis of sporadic basal cell carcinomas and those from repair deficient xeroderma pigmentosum patients has revealed mutational inactivation of PATCHED and gain of function mutations of the proto-oncogenes, SMOOTHENED and SONIC HEDGEHOG associated with solar UV exposure. The molecular mechanisms involved in alterations of the hedgehog signaling pathway that lead to the formation of basal cell carcinomas are being unraveled and has already allowed the investigation of future therapeutic strategies for treating these skin cancers.
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PMID:Sonic hedgehog signaling in basal cell carcinomas. 1597 22