Alberto E. Turco

Association of functional gene variants in the regulatory regions of COX‐2 gene (PTGS2) with nonmelanoma skin cancer after organ transplantation

Summary Background  Overexpression of cyclooxygenase‐2 (COX‐2), resulting in excessive prostaglandin production, has been observed in human epidermal keratinocytes after ultraviolet B injury, in squamous cell skin carcinoma (SCC), in actinic keratoses, and in the early stages of carcinogenesis in a wide variety of tissues. The dysregulation of COX‐2 expression can in part be due to functional changes affecting regulatory elements in the promoter or 3′ untranslated region (UTR) of the gene. Two common polymorphisms (–765G→C, and –1195A→G) in the promoter region of the COX‐2 gene (now PTGS2), and one common polymorphism in the 3′ UTR (8473T→C) have been described, and reported as associated with various malignancies.

Glutathione S-transferase and CYP1A1 gene polymorphisms and non-melanoma skin cancer risk in Italian transplanted patients.

Abstract:  Solid organ transplant recipients are at higher risk of non‐melanoma skin cancer (NMSC), especially basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Genetic alterations in the production of detoxifying enzymes such as glutathione S‐transferase (GST) and CYP1A1 may enhance this risk. We investigated the frequency of GST genotypes (GSTM1, GSTM3, GSTT1 and GSTP1) and CYP1A1 in 239 transplant recipients: 107 cases with NMSC and 132 controls free from NMSC matched for type of transplanted organ, duration of transplantation, sex and age. Allele GSTP1*A was associated with a higher risk of NMSC [odds ratio (OR) 1.7 (1.1–2.5); P = 0.017]. Homozygosity for allele GSTP1 Val105 was lower in cases [OR 0.3 (0.1–0.8); P = 0.012], especially in patients with SCC [OR 0.1 (0.0–0.7); P = 0.012]. A higher risk of BCC was found in patients with GSTM1 null/null [null/null versus A + B, OR 3.1 (1.4–6.8); P = 0.003]. Analysis of allelism and interaction between allelic variants showed significant association between combined GSTM1 and CYP1A1 Val462 genotypes, where individuals homozygous for the risk allele GSTM1 null and carrying also the allele CYP1A1 Val462, show a higher risk of developing NMSC [OR 4.5 (1.1–21.4); P = 0.03], especially SCC [OR 6.5 (1.4–34.4); P = 0.01]. GSTP1 polymorphisms are associated with both BCC and SCC risk. GSTM1 polymorphisms seem to be involved in BCC risk, while GSTM1 null/null genotype combined with CYP1A1 allele Val462 are associated with a higher risk for SCC, indicating that allelism and/or interactions between allelic variants at other loci may also influence the risk of NMSC, particularly SCC.

Linkage analysis for the diagnosis of autosomal dominant polycystic kidney disease, and for the determination of genetic heterogeneity in Italian families

Sixty‐eight individuals from six Italian families in which autosomal dominant polycystic kidney disease (ADPKD) is segregating, were typed in DNA polymorphisms linked to the PKD1 locus on chromosome 16. A total of ten probes were used: 3′ HVR, HMJ1, EKMDA, GGG1, 26–6, VK5B, 218EP6, 24.1, CR1090, and 41.1. Zmax was 4.502 at theta = 0.082 between ADPKD and 3′ HVR, and 4.382, 1.947, and 1.576 between ADPKD and GGG1, 26.6, and 218EP6, respectively, at theta = 0.0. No clear evidence of genetic heterogeneity was found. Multipoint analyses were consistent with linkage to PKD1. Twenty‐nine diagnoses and 16 exclusions made by ultrasonography were confirmed by genotype determinations; in two clinically uncertain cases, DNA analysis predicted one individual as being affected and the other unaffected.

PTCH1 gene haplotype association with basal cell carcinoma after transplantation

Background  Basal cell carcinoma (BCC) is 10 times more frequent in organ transplant recipients (OTRs) than in the general population. Factors in OTRs conferring increased susceptibility to BCC include ultraviolet radiation exposure, immunosuppression, viral infections such as human papillomavirus, phototype and genetic predisposition. The PTCH1 gene is a negative regulator of the hedgehog pathway, that provides mitogenic signals to basal cells in skin. PTCH1 gene mutations cause naevoid BCC syndrome, and contribute to the development of sporadic BCC and other types of cancers. Associations have been reported between PTCH1 polymorphisms and BCC susceptibility in nontransplanted individuals.

A novel missense mutation in exon 3 of the COL4A5 gene associated with late-onset Alport syndrome

We have identified a novel missense transition (362G→A) in exon 3 of the COL4A5 gene in a male patient with late‐onset Alport syndrome. We used non‐isotopic single strand conformation polymorphism, heteroduplex analysis, and automated DNA sequencing. The mutation changes a conserved glycine at codon 54 for an aspartic acid (Gly54Asp), which abolishes a BstNI site. Using restriction analysis, we identified the heterozygous carrier status in the two daughters of the proband. Our findings are in keeping with the hypothesis that slower progressive forms of Alport syndrome are more often associated with missense mutations rather than large deletions or frameshifts. This is the first mutation described in the N‐terminus triple helical 7S domain of the COL4A5 gene in an Alport syndrome patient.

Association of promoter polymorphism −765G>C in the PTGS2 gene with malignant melanoma in Italian patients and its correlation to gene expression in dermal fibroblasts

Prostaglandins, especially prostaglandin E synthetase (PGE2), influence carcinogenesis by promoting cell proliferation, inhibiting apoptosis, stimulating angiogenesis and mediating immune suppression. Cyclooxygenase‐2, coded by the PTGS2 gene, is the key enzyme in the production of prostaglandins. In melanoma, Cox‐2 is over expressed in primary malignant melanoma (MM) and in their corresponding metastases. Polymorphisms in the promoter region of PTGS2 gene can modulate gene expression and could modify individual susceptibility to MM. Two hundred and forty melanoma patients and 342 controls were genotyped for polymorphisms −765G>C (rs20417) and −1195A>G (rs689466). Allele −765C frequency was significantly higher in melanoma patients. No allele frequency differences for −1195A>G polymorphism were observed. Haplotype analysis revealed that the haplotypes carrying the minor alleles were associated to a higher risk of melanoma (P = 0.02). Expression analysis showed that allele −765C is associated to a higher gene expression and could represent a risk allele by affecting the functionality of the promoter.

Analysis of the 3′UTR of the prostaglandin synthetase-2 (PTGS-2 / COX-2) gene in non-melanoma skin cancer after organ transplantation

Abstract:  To define the potential involvement of polymorphisms in the 3′untranslated region (3′UTR) of the prostaglandin synthetase‐2 (PTGS‐2) gene to non‐melanoma skin cancer (NMSC) predisposition after transplantation, we screened for genetic variant, relevant parts of this region. It contains binding sites for trans‐acting factors, an alternative polyadenylation site and putative target sequences for miRNAs. Variant +8473T>C did not appear to play a functional role in the regulation of gene expression in human keratinocyte‐transfected cells. In addition to the well‐known +8473T>C, we identified four polymorphisms: +8293G>C, +10259T>G, +10267G>A and +10335G>A. No allele frequency differences were observed between cases and controls neither for +8473T>C nor for any of the identified polymorphisms, suggesting that polymorphisms in the 3′UTR of the PTGS2 gene are rare and unlikely to represent risk factor for NMSC after transplantation.

Corrigendum to: Glutathione S‐transferase and CYP1A1 gene polymorphisms and non‐melanoma skin cancer risk in Italian transplanted patients

Solid organ transplant recipients are at higher risk of non-melanoma skin cancer (NMSC), especially basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Genetic alterations in the production of detoxifying enzymes such as glutathione S-transferase (GST) and CYP1A1 may enhance this risk. We investigated the frequency of GST genotypes (GSTM1, GSTM3, GSTT1 and GSTP1) and CYP1A1 in 239 transplant recipients: 107 cases with NMSC and 132 controls free from NMSC matched for type of transplanted organ, duration of transplantation, sex and age. Allele GSTP1*A was associated with a higher risk of NMSC [odds ratio (OR) 1.7 (1.1-2.5); P = 0.017]. Homozygosity for allele GSTP1 Val(105) was lower in cases [OR 0.3 (0.1-0.8); P = 0.012], especially in patients with SCC [OR 0.1 (0.0-0.7); P = 0.012]. A higher risk of BCC was found in patients with GSTM1 null/null [null/null versus A + B, OR 3.1 (1.4-6.8); P = 0.003]. Analysis of allelism and interaction between allelic variants showed significant association between combined GSTM1 and CYP1A1 Val(462) genotypes, where individuals homozygous for the risk allele GSTM1 null and carrying also the allele CYP1A1 Val(462), show a higher risk of developing NMSC [OR 4.5 (1.1-21.4); P = 0.03], especially SCC [OR 6.5 (1.4-34.4); P = 0.01]. GSTP1 polymorphisms are associated with both BCC and SCC risk. GSTM1 polymorphisms seem to be involved in BCC risk, while GSTM1 null/null genotype combined with CYP1A1 allele Val(462) are associated with a higher risk for SCC, indicating that allelism and/or interactions between allelic variants at other loci may also influence the risk of NMSC, particularly SCC.RXRs and RARs but also for other nuclear receptors, i.e. the peroxisome proliferator-activated receptor (DR1), thyroid hormone receptor (mainly DR4) and the vitamin D receptor (mainly DR3). Conclusions In this work, we have shown that (i) ATRol and ATRal are capable of modulating gene expression in the cell line; (ii) this modulation is not because of vitamin A metabolism in the cells; (iii) ATRol and ATRal may interact with nuclear receptors.