Susceptibility to basal cell carcinoma: associations with PTCH polymorphisms

PTCH Mutations in Sporadic and Gorlin-syndrome-related Odontogenic Keratocysts

Odontogenic keratocysts are relatively common lesions that may occur in isolation or in association with nevoid basal cell carcinoma syndrome (or Gorlin syndrome). The PTCH gene has been reported to be associated with Gorlin syndrome. We investigated 10 cases of non-syndromic keratocysts and two other cases associated with Gorlin syndrome, looking for PTCH mutations. Four novel and 1 known PTCH mutations were identified in five individual patients. Of the 5 mutations identified, 2 were germ-line mutations (2619C>A; 1338_1339insGCG) in 2 cysts associated with Gorlin syndrome, and 3 were somatic mutations (3124_3129dupGTGTGC; 1361_1364delGTCT; 3913G>T) in 3 non-syndromic cysts. This report describes PTCH mutations in both non-syndromic and Gorlin-syndrome-related odontogenic keratocysts in Chinese patients, and suggests that defects of PTCH are associated with the pathogenesis of syndromic as well as a subset of non-syndromic keratocysts.

Oral mucosal stigmata in hereditary-cancer syndromes: From germline mutations to distinctive clinical phenotypes and tailored therapies

Numerous familial tumor syndromes are associated with distinctive oral mucosal findings, which may make possible an early diagnosis as an efficacious marker for the risk of developing visceral malignancies. In detail, Familial Adenomatous Polyposis (FAP), Gardner syndrome, Peutz-Jeghers syndrome, Cowden Syndrome, Gorlin Syndrome, Lynch/Muir-Torre Syndrome and Multiple Endocrine Neoplasia show specific lesions of the oral mucosa and other distinct clinical and molecular features. The common genetic background of the above mentioned syndromes involve germline mutations in tumor suppressor genes, such as APC, PTEN, PTCH1, STK11, RET, clearly implied in both ectodermal and mesodermal differentiation, being the oral mucosal and dental stigmata frequently associated in the specific clinical phenotypes. The oral and maxillofacial manifestations of these syndromes may become visible several years before the intestinal lesions, constituting a clinical marker that is predictive for the development of intestinal polyps and/or other visceral malignancies. A multidisciplinary approach is therefore necessary for both clinical diagnosis and management of the gene-carriers probands and their family members who have to be referred for genetic testing or have to be investigated for the presence of visceral cancers.

Relation between sonic hedgehog pathway gene polymorphisms and basal cell carcinoma development in the Polish population

In recent decades, increases have been observed in the incidence of nonmelanoma skin cancers, including basal cell carcinoma (BCC) and squamous cell carcinoma. BCC is the most common neoplasm in Caucasian populations. Sonic hedgehog (Shh) pathway impairment plays a key role in BCC pathogenesis, and there is evidence that Shh pathway genetic variations may predispose to BCC development. We genotyped 22 single-nucleotide polymorphisms (SNPs) in 4 Shh pathway genes: SHH, GLI, SMO, and PTCH. The study group consisted of 142 BCC patients and 142 age-matched, sex-matched healthy subjects (controls). SNPs were assessed using the PCR-RFLP method. The genotype distribution for the polymorphisms in the rs104894049 331 A/T SHH, rs104894040 349 T/C SHH, and rs41303402 385 G/A SMO genes differed significantly between the BCC patients and the controls. The presence of CC genotype in the SHH rs104894040 349 T/C polymorphism was linked to the highest risk of BCC development (OR 87.9, p < 0.001). Other genotypes, such as the TT in SHH rs104894049 331 A/T and the GG in SMO rs41303402 385 G/A also statistically raised the risk of BCC, but these associations were weaker. Other investigated polymorphisms showed no statistical differences between patients and controls. The results obtained testify to the importance of the SHH and SMO gene polymorphisms in skin cancerogenesis. These results mainly underline the potential role of SHH3 rs104894040 349 T/C gene polymorphism in the development of skin basal cell carcinomas in patients of Polish origin.

A population-based study of hedgehog pathway gene variants in relation to the dual risk of basal cell carcinoma plus another cancer

INTRODUCTION

A personal history of basal cell carcinoma (BCC) is associated with increased risk of other malignancies, but the reason is unknown. The hedgehog pathway is critical to the etiology of BCC, and is also believed to contribute to susceptibility to other cancers. This study tested the hypothesis that hedgehog pathway and pathway-related gene variants contribute to the increased risk of subsequent cancers among those with a history of BCC.

METHODS

The study was nested within the ongoing CLUE II cohort study, established in 1989 in Washington County, Maryland, USA. The study consisted of a cancer-free control group (n=2296) compared to three different groups of cancer cases ascertained through 2007, those diagnosed with: (1) Other (non-BCC) cancer only (n=2349); (2) BCC only (n=534); and (3) BCC plus other cancer (n=446). The frequencies of variant alleles were compared among these four groups for 20 single nucleotide polymorphisms (SNPs) in 6 hedgehog pathway genes (SHH, IHH, PTCH2, SMO, GLI1, SUFU), and also 22 SNPs in VDR and 8 SNPs in FAS, which have cross-talk with the hedgehog pathway.

RESULTS

Comparing those with both BCC and other cancer versus those with no cancer, no significant associations were observed for any of the hedgehog pathway SNPs, or for the FAS SNPs. One VDR SNP was nominally significantly associated with the BCC cancer-prone phenotype, rs11574085 [per minor allele odds ratio (OR) 1.38, 95% confidence interval (CI) 1.05-1.82; p-value=0.02].

CONCLUSION

The hedgehog pathway gene SNPs studied, along with the VDR and FAS SNPs studied, are not strongly associated with the BCC cancer-prone phenotype.

Association of a mineralocorticoid receptor gene polymorphism with hypertension in a Spanish population

BACKGROUND

To assess the association of polymorphisms and haplotypes of the mineralocorticoid receptor (MR) (NR3C2) gene to the risk of essential hypertension (HTN) in a Spanish population.

METHODS

This is a population-based study which included 1,502 subjects (748 women) >18 years old. Twenty-four polymorphisms of NR3C2 gene were analyzed by using SNPlex (Genotyping System based on OLA/PCR technology).

RESULTS

Alleles of the single-nucleotide polymorphism (SNP) rs5522 were significantly associated with the risk of HTN, both in the recessive and codominant models adjusted by age, gender, and body mass index (BMI). Genotype GG of the rs5522 showed to be protective against HTN odds ratio (OR) 0.10 (0.02-0.56), P < 0.01. One haplotype, which included the G allele of the rs5522, was also associated with reduced risk of HTN and four haplotypes which included the A allele were associated with increased risk of HTN. When the 24-h urinary sodium excretion and the estimated glomerular filtration rate (eGFR) were added, they did not reduce the significance level. Interaction between genotypes of the rs5522 and quartiles of 24-h sodium excretion has been observed. In subjects with the AA genotype, those with higher urinary sodium excretion had the lowest risk to be hypertensive.

CONCLUSION

A functional polymorphism of the NR3C2 gene was associated with risk of HTN. The data provided in this study seems to give credit to the hypothesis of the participation of MR gene in the development of HTN, although further studies are necessary to better assess its real impact.

Nevoid basal cell carcinoma syndrome (Gorlin syndrome)

Nevoid basal cell carcinoma syndrome (NBCCS), also known as Gorlin syndrome, is a hereditary condition characterized by a wide range of developmental abnormalities and a predisposition to neoplasms.

The estimated prevalence varies from 1/57,000 to 1/256,000, with a male-to-female ratio of 1:1.

Main clinical manifestations include multiple basal cell carcinomas (BCCs), odontogenic keratocysts of the jaws, hyperkeratosis of palms and soles, skeletal abnormalities, intracranial ectopic calcifications, and facial dysmorphism (macrocephaly, cleft lip/palate and severe eye anomalies). Intellectual deficit is present in up to 5% of cases. BCCs (varying clinically from flesh-colored papules to ulcerating plaques and in diameter from 1 to 10 mm) are most commonly located on the face, back and chest. The number of BBCs varies from a few to several thousand. Recurrent jaw cysts occur in 90% of patients. Skeletal abnormalities (affecting the shape of the ribs, vertebral column bones, and the skull) are frequent. Ocular, genitourinary and cardiovascular disorders may occur. About 5–10% of NBCCS patients develop the brain malignancy medulloblastoma, which may be a potential cause of early death.

NBCCS is caused by mutations in the PTCH1 gene and is transmitted as an autosomal dominant trait with complete penetrance and variable expressivity.

Clinical diagnosis relies on specific criteria. Gene mutation analysis confirms the diagnosis. Genetic counseling is mandatory. Antenatal diagnosis is feasible by means of ultrasound scans and analysis of DNA extracted from fetal cells (obtained by amniocentesis or chorionic villus sampling). Main differential diagnoses include Bazex syndrome, trichoepithelioma papulosum multiplex and Torre's syndrome (Muir-Torre's syndrome).

Management requires a multidisciplinary approach. Keratocysts are treated by surgical removal. Surgery for BBCs is indicated when the number of lesions is limited; other treatments include laser ablation, photodynamic therapy and topical chemotherapy. Radiotherapy should be avoided. Vitamin A analogs may play a preventive role against development of new BCCs.

Life expectancy in NBCCS is not significantly altered but morbidity from complications can be substantial. Regular follow-up by a multi-specialist team (dermatologist, neurologist and odontologist) should be offered. Patients with NBCCS should strictly avoid an excessive sun exposure.

A Bayesian measure of the probability of false discovery in genetic epidemiology studies

In light of the vast amounts of genomic data that are now being generated, we propose a new measure, the Bayesian false-discovery probability (BFDP), for assessing the noteworthiness of an observed association. BFDP shares the ease of calculation of the recently proposed false-positive report probability (FPRP) but uses more information, has a noteworthy threshold defined naturally in terms of the costs of false discovery and nondiscovery, and has a sound methodological foundation. In addition, in a multiple-testing situation, it is straightforward to estimate the expected numbers of false discoveries and false nondiscoveries. We provide an in-depth discussion of FPRP, including a comparison with the q value, and examine the empirical behavior of these measures, along with BFDP, via simulation. Finally, we use BFDP to assess the association between 131 single-nucleotide polymorphisms and lung cancer in a case-control study.

UV fingerprints predominate in the PTCH mutation spectra of basal cell carcinomas independent of clinical phenotype

Basal cell carcinoma (BCC) shows a wide interpatient variation in lesion accrual. To determine whether certain tumorigenic fingerprints and potentially predisposing patched (PTCH) tumor suppressor single-nucleotide polymorphisms (SNPs) are distributed differently among sporadic BCC patients, we compared the PTCH mutation spectra in early-onset BCC (first lesion at age < 35 years), regular BCC (first lesion at age > or = 35 years and < 10 lesions), and multiple BCC (> or = 10 lesions). The PTCH gene was mutated in 29 of 60 cases (48%). Most of the PTCH mutations bore the UV fingerprint (i.e., C --> T or tandem CC --> TT transitions at dipyrimidine sites). However, neither the proportion nor the spectra of exonic PTCH mutations differed significantly among the three groups. A large number of SNPs (IVS10+99C/T, IVS11-51G/C, 1665T/C, 1686C/T, IVS15+9G/C, IVS16-80G/C, IVS17+21G/A, and 3944C/T or its combinations) were also detected, but again their incidence did not differ significantly among the groups. Interestingly, expression of the IVS16-80G/C and the IVS17+21G/A genotype did not achieve the Hardy-Weinberg equilibrium in patients with regular and/or early-onset BCC. These data suggest that a (UV-) mutated PTCH gene is important for sporadic BCC formation independent of clinical phenotype and that the IVS16-80G/C and/or IVS17+21G/A SNP site might be important for tumorigenesis in certain BCC patients.

The effects on human health from stratospheric ozone depletion and its interactions with climate change

Ozone depletion leads to an increase in the ultraviolet-B (UV-B) component (280-315 nm) of solar ultraviolet radiation (UVR) reaching the surface of the Earth with important consequences for human health. Solar UVR has many harmful and some beneficial effects on individuals and, in this review, information mainly published since the previous report in 2003 (F. R. de Gruijl, J. Longstreth, M. Norval, A. P. Cullen, H. Slaper, M. L. Kripke, Y. Takizawa and J. C. van der Leun, Photochem. Photobiol. Sci., 2003, 2, pp. 16-28) is discussed. The eye is exposed directly to sunlight and this can result in acute or long-term damage. Studying how UV-B interacts with the surface and internal structures of the eye has led to a further understanding of the location and pathogenesis of a number of ocular diseases, including pterygium and cataract. The skin is also exposed directly to solar UVR, and the development of skin cancer is the main adverse health outcome of excessive UVR exposure. Skin cancer is the most common form of malignancy amongst fair-skinned people, and its incidence has increased markedly in recent decades. Projections consistently indicate a further doubling in the next ten years. It is recognised that genetic factors in addition to those controlling pigment variation can modulate the response of an individual to UVR. Several of the genetic factors affecting susceptibility to the development of squamous cell carcinoma, basal cell carcinoma and melanoma have been identified. Exposure to solar UVR down-regulates immune responses, in the skin and systemically, by a combination of mechanisms including the generation of particularly potent subsets of T regulatory cells. Such immunosuppression is known to be a crucial factor in the generation of skin cancers. Apart from a detrimental effect on infections caused by some members of the herpesvirus and papillomavirus families, the impact of UV-induced immunosuppression on other microbial diseases and vaccination efficacy is not clear. One important beneficial effect of solar UV-B is its contribution to the cutaneous synthesis of vitamin D, recognised to be a crucial hormone for bone health and for other aspects of general health. There is accumulating evidence that UVR exposure, either directly or via stimulation of vitamin D production, has protective effects on the development of some autoimmune diseases, including multiple sclerosis and type 1 diabetes. Adequate vitamin D may also be protective for the development of several internal cancers and infections. Difficulties associated with balancing the positive effects of vitamin D with the negative effects of too much exposure to solar UV-B are considered. Various strategies that can be adopted by the individual to protect against excessive exposure of the eye or the skin to sunlight are suggested. Finally, possible interactions between ozone depletion and climate warming are outlined briefly, as well as how these might influence human behaviour with regard to sun exposure.

PTCH mutations and deletions in patients with typical nevoid basal cell carcinoma syndrome and in patients with a suspected genetic predisposition to basal cell carcinoma: a French study

The patched (PTCH) mutation rate in nevoid basal cell carcinoma syndrome (NBCCS) reported in various studies ranges from 40 to 80%. However, few studies have investigated the role of PTCH in clinical conditions suggesting an inherited predisposition to basal cell carcinoma (BCC), although it has been suggested that PTCH polymorphisms could predispose to multiple BCC (MBCC). In this study, we therefore performed an exhaustive analysis of PTCH (mutations detection and deletion analysis) in 17 patients with the full complement of criteria for NBCCS (14 sporadic and three familial cases), and in 48 patients suspected of having a genetic predisposition to BCC (MBCC and/or age at diagnosis ⩽40 years and/or familial BCC). Eleven new germline alterations of the PTCH gene were characterised in 12 out of 17 patients harbouring the full complement of criteria for the syndrome (70%). These were frameshift mutations in five patients, nonsense mutations in five patients, a small inframe deletion in one patient, and a large germline deletion in another patient. Only one missense mutation (G774R) was found, and this was in a patient affected with MBCC, but without any other NBCCS criterion. We therefore suggest that patients harbouring the full complement of NBCCS criteria should as a priority be screened for PTCH mutations by sequencing, followed by a deletion analysis if no mutation is detected. In other clinical situations that suggest genetic predisposition to BCC, germline mutations of PTCH are not common.

Hedgehog signaling and Bmi-1 regulate self-renewal of normal and malignant human mammary stem cells

The epithelial components of the mammary gland are thought to arise from stem cells with a capacity for self-renewal and multilineage differentiation. Furthermore, these cells and/or their immediate progeny may be targets for transformation. We have used both in vitro cultivation and a xenograft mouse model to examine the role of hedgehog signaling and Bmi-1 in regulating self-renewal of normal and malignant human mammary stem cells. We show that hedgehog signaling components PTCH1, Gli1, and Gli2 are highly expressed in normal human mammary stem/progenitor cells cultured as mammospheres and that these genes are down-regulated when cells are induced to differentiate. Activation of hedgehog signaling increases mammosphere-initiating cell number and mammosphere size, whereas inhibition of the pathway results in a reduction of these effects. These effects are mediated by the polycomb gene Bmi-1. Overexpression of Gli2 in mammosphere-initiating cells results in the production of ductal hyperplasia, and modulation of Bmi-1 expression in mammosphere-initiating cells alters mammary development in a humanized nonobese diabetic-severe combined immunodeficient mouse model. Furthermore, we show that the hedgehog signaling pathway is activated in human breast "cancer stem cells" characterized as CD44+CD24-/lowLin-. These studies support a cancer stem cell model in which the hedgehog pathway and Bmi-1 play important roles in regulating self-renewal of normal and tumorigenic human mammary stem cells.

Hedgehog signaling and Bmi-1 regulate self-renewal of normal and malignant human mammary stem cells

The epithelial components of the mammary gland are thought to arise from stem cells with a capacity for self-renewal and multilineage differentiation. Furthermore, these cells and/or their immediate progeny may be targets for transformation. We have used both in vitro cultivation and a xenograft mouse model to examine the role of hedgehog signaling and Bmi-1 in regulating self-renewal of normal and malignant human mammary stem cells. We show that hedgehog signaling components PTCH1, Gli1, and Gli2 are highly expressed in normal human mammary stem/progenitor cells cultured as mammospheres and that these genes are down-regulated when cells are induced to differentiate. Activation of hedgehog signaling increases mammosphere-initiating cell number and mammosphere size, whereas inhibition of the pathway results in a reduction of these effects. These effects are mediated by the polycomb gene Bmi-1. Overexpression of Gli2 in mammosphere-initiating cells results in the production of ductal hyperplasia, and modulation of Bmi-1 expression in mammosphere-initiating cells alters mammary development in a humanized nonobese diabetic-severe combined immunodeficient mouse model. Furthermore, we show that the hedgehog signaling pathway is activated in human breast "cancer stem cells" characterized as CD44+CD24-/lowLin-. These studies support a cancer stem cell model in which the hedgehog pathway and Bmi-1 play important roles in regulating self-renewal of normal and tumorigenic human mammary stem cells.

Case-control study in basal cell carcinoma of the skin: single nucleotide polymorphisms in three interleukin promoters pre-analysed in pooled DNA

BACKGROUND

Basal cell carcinoma (BCC) is one of the most common neoplasms in the world. Development of BCC is associated with environmental factors (especially sun exposure) as well as heritable factors.

OBJECTIVES

To analyse three single nucleotide polymorphisms (SNPs) in the promoter regions of interleukin (IL) genes in genomic DNA from 527 cases of BCC and 530 matched controls and to examine if DNA pooling is a useful method on which to base decisions regarding further SNP analysis.

METHODS

The SNPs analysed were IL6-597, IL10-1082 and IL1B-511. The SNPs were first analysed from pooled DNA and afterwards from individual samples. The DNA pools resulted from a division of the samples into cases and controls, female and male, and three age groups. In these pools the allele frequencies were estimated by two methods, real-time polymerase chain reaction with allele-specific primers, and quantitative sequencing.

RESULTS

No significant association was found when the allele frequencies in cases and controls were compared. However, by analysis of the individual genotypes we found SNP IL6-597 G/A to be significantly associated with BCC risk (P =0.007). Hereby the heterozygous genotype 'GA' had a protective effect (odds ratio 0.64, 95% confidence interval 0.49-0.84). No significant association was found for IL10-1082 and IL1B-511.

CONCLUSIONS

The association of SNP IL6-597 with BCC could be found only by individual genotyping, but would have been missed if only data from the pooling analysis had been known.

Polymorphism in the nuclear excision repair gene ERCC2/XPD: association between an exon 6-exon 10 haplotype and susceptibility to cutaneous basal cell carcinoma

Cutaneous basal cell carcinoma (BCC) risk is mediated by interactions between ultraviolet radiation (UVR) and host factors, including DNA repair efficiency. We investigated the association between BCC risk and SNPs in exon 6 (c.466C > A, dbSNP238406:g.C > A; designated C/A156), exon 10 (c.932G > A, dbSNP1799793:g.G > A; designated G/A312), and exon 23 (c.2251A > C, dbSNP13181:g.A > C; designated A/C751) of the nucleotide excision repair gene, XPD (ERCC2; excision repair cross-complementing repair deficiency, complementation 2 [xeroderma pigmentosum D]). XPD genotype frequencies were not significantly different in 509 cases and 379 controls, although AA156 (odds ratio [OR]=0.61, 95% confidence interval [CI]=0.37-1.01, P=0.052) and AA312 (OR=0.65, 95% CI=0.40-1.05, P=0.08) were linked with reduced risk. A156-A312 and A156-A312-A751 haplotype frequencies however, were significantly lower in cases than controls (OR=0.12, 95% CI=0.05-0.31, P < 0.001; OR=0.10, 95% CI=0.03-0.33, P < 0.001). We confirmed the robustness of these findings by showing significant associations of the haplotypes with risk in two randomly selected equal sized groups of cases and controls and, using the false positive report probability (FPRP) approach (FPRP values < 0.001 and < 0.004, respectively). A156-A312 was similarly associated with reduced risk in subgroups, including cases with no family history of skin cancer, with only BCC on the head/neck, and those with a high rate of increase in BCC numbers. The association was not dependent on gender, age, or extent of UVR exposure. A156-A312 was found in 6.3% of controls and the corresponding risk haplotype, C156-G312 (OR=1.65, 95% CI=1.21-2.26, P=0.002) in 35.4% of controls. We interpret these data as showing that XPD SNP mediate susceptibility to BCC.

MC1R and PTCH Gene Polymorphism in French Patients with Basal Cell Carcinomas

In this study, we assessed the role of melanocortin 1 receptor (MC1R) variants and of two patched (PTCH) polymorphisms (c.3944C>T (P1315L), insertion 18 bp IVS1-83) as risk factors for basal cell carcinoma (BCC) in the French population. The population investigated comprised 126 BCC patients who were enrolled on the basis of specific criteria (multiple and/or familial BCC and/or onset before the age of 40 years and/or association with another tumor)--and 151 controls matched for ethnicity, age, and sex. MC1R variants appeared as a moderate risk factor for BCC (odds ratio (OR) for one and two variants, 2.17 [1.28-3.68] and 7.72 [3.42-17.38], respectively), independently of pigmentation characteristics (OR = 2.53 [1.34-4.8]). Interestingly, in addition to the predictable red hair color (RHC) alleles, two non-RHC alleles (V60L and V92M) were also closely associated with BCC risk (OR 3.21 [1.91-5.38] and 2.87 [1.5-5.48], respectively), which differs from the situation in the Celtic population. In addition, the PTCH c.3944C/C genotype was also associated with BCC risk (OR 1.94 [1.2-3.1]), especially in the subgroup of patients with multiple tumors (OR 2.16 [1.3-3.6]). Thus, our data show that MC1R and PTCH variants are associated with BCC risk in the French population. We further suggest that assessing MC1R and PTCH status could be useful, combined with the assessment of clinical risk factors, in identifying high-risk patients to be targeted for prevention or more rigorous surveillance.