Infrequent p53 gene mutation but UV gradient-like p53 protein positivity in keloids.

Keloids are characterized by extreme fibroblastic overgrowth of unknown pathogenesis after skin injury. Previous studies, mostly in non-Caucasian populations, suggest that p53 mutations may be involved. To substantiate this, we performed DNA sequence analysis of exons 4-8 of the p53 gene and immunohistochemical staining of p53 protein in archived keloidal tissue samples from 23 Caucasian patients. In contrast to previous reports, we found mutated p53 in keloidal tissue in a minority of cases (2/23; 12%). The G allele frequency and C allele frequency at the p53 polymorphic codon 72 were 0.72 (33/46) and 0.28 (13/46), respectively, in our study, a finding that was similar to the 0.77 (184/240) vs. 0.23 (56/240) (P = 0.4580; chi-squared test) observed in the Hap Map data of a European population but statistically significantly different from the 0.43 (547/1258) vs. 0.57 (711/1258) (P = 0.0002; chi-squared test) observed in the 1000 Genome project [Database of Single Nucleotide Polymorphisms (dbSNP). Bethesda (MD): National Center for Biotechnology Information, National Library of Medicine. dbSNP accession:rs1042522, (dbSNP Build ID: 132). Available from: (http://www.ncbi.nlm.nih.gov/SNP/] a difference most likely due to the different genetic background of the populations enrolled. However, one-third of the keloidal samples showed lesional nuclear p53 staining with a UV penetration gradient-like positivity (P ≤ 0.0084). Staining with an anti-cyclobutane pyrimidine dimer antibody revealed the total absence of short-term photoproducts in the epidermis as well as keloidal tissue. Furthermore, all fibroblasts expressing p53 stained negative for Ki-67, indicating that these cells were in a quiescent stage and p53 upregulation did not contribute to keloidal proliferation. We conclude that p53 plays no major role in the pathogenesis of keloids in the Caucasian population.

Profiles of chemokine receptors in melanocytic lesions: de novo expression of CXCR6 in melanoma.

Selective expression of certain chemokine receptors by melanoma cells and the presence of their ligands in tissues might govern organ site-specific metastasis. Because the expression profile of chemokine receptors in tissues of melanocytic origin is unknown, we performed a comprehensive study on melanocytic tissue samples investigating the expression of 18 chemokine receptors at the mRNA level by real-time polymerase chain reaction, using a semiquantitative approach, and of 3 chemokine receptors (CXCR6, CCR9, and XCR1) at the protein level. We report on the de novo expression of CXCR6 in primary melanomas and melanoma metastases, but absence in melanoma cell lines and congenital nevi. CXCR4 and CCR1 were the only 2 chemokine receptors that were consistently expressed in melanocytes, melanoma cell lines, primary, and metastatic melanoma; CCR1 expression increased significantly over progression. CCR9 and XCR1 transcripts were found in melanocytic lesions, and expression was confirmed by immunohistochemistry. Transcripts for CCR10 were not found in any of the lesions, but in some melanoma cell lines. Expression of CCR7 was observed in primary melanomas and some metastases. CCR5 was exclusively expressed in primary melanomas and some cutaneous metastases. Results revealed a restricted and differential pattern of chemokine receptor expression in melanoma tissue, which varies substantially from the expression profile of melanoma cell lines and warrants functional studies on some receptors.

Increased prevalence of human papillomavirus in hairs plucked from patients with psoriasis treated with psoralen-UV-A.

BACKGROUND: Patients with psoriasis treated with psoralen-UV-A (PUVA) are at increased risk of skin cancer; however, the exact causes of this increased incidence are not well understood. It has been suggested that PUVA may increase expression of the tumorigenic agent human papillomavirus (HPV) in skin by directly stimulating virus replication, immune suppression, or both, thereby leading to skin cancer formation. OBJECTIVE: To determine whether HPV DNA prevalence in the skin is increased after long-term PUVA treatment. DESIGN: Screening for the presence of HPV sequences in DNA isolated from plucked body hairs of patients with psoriasis with a history of PUVA exposure and a history of skin cancer (group A), PUVA exposure and no history of skin cancer (group B), and no PUVA exposure and no history of skin cancer (group C). SETTING: University hospital. PATIENTS AND METHODS: Hair samples were obtained from 81 patients with psoriasis (56 men and 25 women; mean age, 52 years), including 16 in group A (mean number of PUVA exposures, 702), 35 in group B (mean number of PUVA exposures, 282), and 30 in group C. DNA was isolated from the hair samples and analyzed by polymerase chain reaction with the use of 2 nested primer systems specific for epidermodysplasia verruciformis-associated or related and genital or mucosal virus types, respectively. RESULTS: The rate of HPV DNA positivity was significantly higher in groups A (73% [11/15]) and B (69% [24/35]) than in group C (36% [10/28]) (A + B vs C, P =.009; chi(2) test; age adjusted). Conclusion The prevalence of HPV in the skin (hair follicles) is increased in patients with psoriasis who have a history of PUVA exposure.

The ultraviolet fingerprint dominates the mutational spectrum of the p53 and Ha-ras genes in psoralen + ultraviolet A keratoses from psoriasis patients.

Psoriasis patients exposed to high cumulative doses of psoralen + ultraviolet A frequently exhibit so-called "psoralen + ultraviolet A keratoses" (i.e., hyperkeratotic lesions with varying degrees of histologic atypia). The exact causes and molecular mechanisms of psoralen + ultraviolet A keratoses however, are not clear. We therefore performed DNA mutational analysis of the tumor suppressor gene p53 (exons in psoralen + ultraviolet A keratoses from 10 long-term psoralen + ultraviolet A-treated psoriasis patients. We detected 39 p53 mutations in 16 of 28 psoralen + ultraviolet A keratoses (57%) and 18 Ha-ras mutations in 11 of 25 psoralen + ultraviolet A keratoses (44%). Of the 39 p53 mutations and 18 Ha-ras mutations, 22 (56%) and 13 (72%), respectively, were of the ultraviolet fingerprint type (C-->T or CC-->TT transitions at dipyrimidine sites); 13 (33%) and two (11%), respectively, occurred at potential psoralen-binding sites (5'-TpA, 5'-TpG, or 5'-TpT DNA sequences) and were potentially psoralen + ultraviolet A induced; two (5%) and three (17%), respectively, were of ambiguous origin (ultraviolet and/or psoralen + ultraviolet A); and two (5%) and none (0%), respectively, were of the "other" type, respectively. We conclude that (1) the frequent mutation of p53 and Ha-ras may play a key part in the formation of at least some psoralen + ultraviolet A keratoses; (2) environmental and/or therapeutic ultraviolet exposure may be a major cause of psoralen + ultraviolet A keratosis as most Ha-ras and p53 mutations are induced by ultraviolet light; and (3) psoralen + ultraviolet A itself plays a smaller, though direct, role in causing these mutations.

High frequency of ultraviolet mutations at the INK4a-ARF locus in squamous cell carcinomas from psoralen-plus-ultraviolet-A-treated psoriasis patients.

Squamous cell carcinomas in psoralen-plus-ultraviolet A (PUVA) treated patients frequently exhibit p53 tumor suppressor genes and Ha-ras protooncogenes that are mutated at dipyrimidine sites and carry the ultraviolet fingerprint (i.e., C-to-T or CC-to-TT transitions). To further broaden the knowledge of genetic mutations in PUVA-associated skin cancer, we used DNA sequencing analysis to study the mutational spectrum of the INK4a-ARF locus in 26 squamous cell carcinomas from 11 long-term PUVA-treated psoriasis patients and classified the mutations by origin (ultraviolet, ultraviolet and/or PUVA, or other). Nineteen INK4a-ARF missense/nonsense mutations were found in exons 1alpha, 1beta, and 2 in 11 of 26 squamous cell carcinomas (42%) from seven of 11 patients (64%). Eleven mutations (58%) were of the ultraviolet type; three (16%) were of the ultraviolet and/or PUVA type (i.e., C-to-T transitions at dipyrimidine sites opposite a 5'TpG sequence, a potential psoralen binding site); and five (26%) were of other type. Interestingly, 10 of 11 patients (91%) showed intron polymorphism C500G at the 3' untranslated region of exon 3. These data indicate that (i) INK4a-ARF mutations frequently occur in PUVA-associated squamous cell carcinomas; (ii) ultraviolet B radiation is the major cause of these mutations; and (iii) PUVA itself may play no direct role in development of most INK4a-ARF mutations.