title: The DNA damage-binding protein XPC is a frequent target for inactivation in squamous cell carcinomas.
abstract: XPC, the main damage-recognition protein responsible for nucleotide excision repair of UVB damage to DNA, is lost or mutated in xeroderma pigmentosum group C (XP-C), a rare inherited disease characterized by high incidence and early onset of non-melanoma and melanoma skin cancers. The high incidence of skin cancers in XP-C patients suggests that loss of expression of XPC protein might also provide a selective advantage for initiation and progression of similar cancers in non XP-C patients in the general population. To test whether XPC is selectively lost in squamous cell carcinomas from non XP-C patients, we examined XPC expression by immunohistochemistry on a tissue microarray with 244 tissue cores, including in situ and invasive squamous-cell carcinomas (SCCs), keratoacanthoma (KA), and normal skin samples from both immunocompetent and immunosuppressed patients. We found that XPC expression was lost in 49% of invasive squamous cell carcinomas from immunocompetent patients and 59% from immunosuppressed patients. Loss of expression was correlated with deletions of chromosomal 3p and mutations in the XPC gene. The XPC gene is consequently inactivated or lost in almost half of squamous cell carcinomas from non XP-C patients. Loss or mutation of XPC may be an early event during skin carcinogenesis that provides a selective advantage for initiation and progression of squamous cell carcinomas in non XP-C patients.
authors.affiliation: Department of Dermatology, University of California, San Francisco, CA 94143-0808, USA.
authors.forename: Sebastien
authors.initials: S
authors.lastname: de Feraudy
authors.forename: Katie
authors.initials: K
authors.lastname: Ridd
authors.forename: Lauren M
authors.initials: LM
authors.lastname: Richards
authors.forename: Pui-Yan
authors.initials: PY
authors.lastname: Kwok
authors.forename: Ingrid
authors.initials: I
authors.lastname: Revet
authors.forename: Dennis
authors.initials: D
authors.lastname: Oh
authors.forename: Luzviminda
authors.initials: L
authors.lastname: Feeney
authors.forename: James E
authors.initials: JE
authors.lastname: Cleaver
mesh_terms: D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000473:pathology; D002460:Cell Line; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000235:genetics*; D020868:Gene Silencing; D006801:Humans; D046228:Microarray Analysis; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D014983:Xeroderma Pigmentosum / Q000235:genetics / Q000473:pathology
chemical_list: D004268:DNA-Binding Proteins; D016159:Tumor Suppressor Protein p53; C086984:XPC protein, human