M.A.M. van Steensel

Molecular aetiology and pathogenesis of basal cell carcinoma

Recent insights into the cell biology of the epidermis and its appendages are transforming our understanding of the pathogenesis of basal cell carcinoma (BCC). The significant progress that has been made warrants a comprehensive review of the molecular and cellular pathology of BCC. The items addressed include environmental and genetic risk factors, the biology of the putative precursor cell(s), and the contribution of aberrations in processes such as apoptosis, cell proliferation, differentiation and signalling to carcinogenesis. Furthermore, established and novel treatment modalities are discussed with particular attention to future biological approaches.

HID and KID syndromes are associated with the same connexin 26 mutation

Summary Background Keratitis–ichthyosis–deafness (KID) syndrome is a debilitating ectodermal dysplasia that predisposes patients to develop squamous cell carcinomas in addition to leading to profound sensory deafness and erythrokeratoderma. We recently demonstrated that KID can be caused by a specific missense mutation in connexin 26 (GJB2). Another syndrome, called hystrix‐like ichthyosis–deafnesss (HID) syndrome, strongly resembles the KID syndrome. These disorders are distinguished mainly on the basis of electron microscopic findings. We hypothesized that KID and HID syndromes may be genetically related.

Hereditary leiomyomatosis and renal cell cancer in families referred for fumarate hydratase germline mutation analysis

Smit DL, Mensenkamp AR, Badeloe S, Breuning MH, Simon MEH, van Spaendonck KY, Aalfs CM, Post JG, Shanley S, Krapels IPC, Hoefsloot LH, van Moorselaar RJA, Starink TM, Bayley J‐P, Frank J, van Steensel MAM, Menko FH. Hereditary leiomyomatosis and renal cell cancer in families referred for fumarate hydratase germline mutation analysis.

Mutations in the gene encoding the Wnt-signaling component R-spondin 4 (RSPO4) cause autosomal recessive anonychia.

Anonychia is an autosomal recessive disorder characterized by the congenital absence of finger- and toenails. In a large German nonconsanguineous family with four affected and five unaffected siblings with isolated total congenital anonychia, we performed genomewide mapping and showed linkage to 20p13. Analysis of the RSPO4 gene within this interval revealed a frameshift and a nonconservative missense mutation in exon 2 affecting the highly conserved first furin-like cysteine-rich domain. Both mutations were not present among controls and were shown to segregate with the disease phenotype. RSPO4 is a member of the recently described R-spondin family of secreted proteins that play a major role in activating the Wnt/ beta -catenin signaling pathway. Wnt signaling is evolutionarily conserved and plays a pivotal role in embryonic development, growth regulation of multiple tissues, and cancer development. Our findings add to the increasing body of evidence indicating that mesenchymal-epithelial interactions are crucial in nail development and put anonychia on the growing list of congenital malformation syndromes caused by Wnt-signaling-pathway defects. To the best of our knowledge, this is the first gene known to be responsible for an isolated, nonsyndromic nail disorder.

Renal cancer and pneumothorax risk in Birt-Hogg-Dubé syndrome; an analysis of 115 FLCN mutation carriers from 35 BHD families.

Background:Birt–Hogg–Dubé (BHD) syndrome is an autosomal dominant condition caused by germline FLCN mutations, and characterised by fibrofolliculomas, pneumothorax and renal cancer. The renal cancer risk, cancer phenotype and pneumothorax risk of BHD have not yet been fully clarified. The main focus of this study was to assess the risk of renal cancer, the histological subtypes of renal tumours and the pneumothorax risk in BHD.Methods:In this study we present the clinical data of 115 FLCN mutation carriers from 35 BHD families.Results:Among 14 FLCN mutation carriers who developed renal cancer 7 were <50 years at onset and/or had multifocal/bilateral tumours. Five symptomatic patients developed metastatic disease. Two early-stage cases were diagnosed by surveillance. The majority of tumours showed characteristics of both eosinophilic variants of clear cell and chromophobe carcinoma. The estimated penetrance for renal cancer and pneumothorax was 16% (95% minimal confidence interval: 6–26%) and 29% (95% minimal confidence interval: 9–49%) at 70 years of age, respectively. The most frequent diagnosis in families without identified FLCN mutations was familial multiple discoid fibromas.Conclusion:We confirmed a high yield of FLCN mutations in clinically defined BHD families, we found a substantially increased lifetime risk of renal cancer of 16% for FLCN mutation carriers. The tumours were metastatic in 5 out of 14 patients and tumour histology was not specific for BHD. We found a pneumothorax risk of 29%. We discuss the implications of our findings for diagnosis and management of BHD.

A 2‐bp deletion in the GJA1 gene is associated with oculo‐dento‐digital dysplasia with palmoplantar keratoderma

Oculo‐dento‐digital dysplasia (ODDD, OMIM no. 164210) is a pleiotropic disorder characterized mainly by ocular anomalies, varying degrees of finger and toe syndactyly, and enamel defects. It is caused by missense mutations in the gene coding for the gap junction protein connexin 43 or GJA1. Other types of mutations have so far not been reported. Here we describe a Dutch kindred with ODDD showing a new symptom, palmoplantar keratoderma, and associated with a novel 2‐bp deletion mutation of GJA1. The dinucleotide deletion 780_781delTG is located in the cytoplasmic C‐terminal loop and leads to a frameshift. This is predicted to lead to the production of a slightly truncated protein with 46 incorrect amino acids in the C‐terminal cytoplasmic loop (C260fsX307). This novel mutation may explain the presence of skin symptoms.

Erysipelas as a sign of subclinical primary lymphoedema: a prospective quantitative scintigraphic study of 40 patients with unilateral erysipelas of the leg

Background  Erysipelas is a common skin infection that is usually caused by β‐haemolytic group A streptococci. After having had erysipelas in an extremity, a significant percentage of patients develops persistent swelling or suffers from recurrent erysipelas. We hypothesize that in cases of erysipelas without a clear precipitating agent, subclinical pre‐existing congenital or acquired disturbances in the function of the lymphatic system are present. The persistent swelling after erysipelas is then most likely caused by lymphoedema.

A missense mutation in the type II hair keratin hHb3 is associated with monilethrix

Monilethrix (MIM #158 000) is an autosomal dominant hair disorder that can cause scarring alopecia in affected individuals.1 Nail changes and keratosis pilaris of the skin of neck and arms have also been described. The hallmark hair abnormality in monilethrix is a beading of the hair shaft caused by periodic narrowing with the nodes separated by about 0.7 mm. The cause of the beading is unknown. The expression of monilethrix is variable.2 In mild cases, dystrophic hairs may be found only on the occiput, but severely affected individuals may suffer complete alopecia. Most cases described so far are associated with mutations in the type II (basic) trichocyte keratin genes hHb1 and hHb6 .2,3,4,5,6,7,8,9,10,11,12,13,14 Both genes have a mutational hotspot in the region coding for the helix termination motif. Most mutations seem to affect the same residues—glutamic acids at positions 413 and 402.3,6,10,15 Mutations affecting the helix initiation motif have also been found.7 From the phenotype, it is apparent that hHb1 and hHb6 are major hair cortex keratins. A third type II trichocyte keratin, hHb3, is expressed in much the same pattern as hHb1.16 From this, it may be expected that mutations of hHb3 may cause monilethrix as well. However, mutations in this gene have so far not been described. We analysed three patients suffering from monilethrix for the presence of mutations in hHb1 , hHb3 , and hHb6 . In one patient, we found a heterozygous missense mutation in hHb3 causing the substitution of a glutamic acid by a lysine at position 407 in the helix termination motif (E407K). This mutation corresponds to the E402K substitution in hHb1 and hHb6, clearly defining this particular residue as a trichocyte keratin …

Absence of the Birt-Hogg-Dubé gene product is associated with increased hypoxia-inducible factor transcriptional activity and a loss of metabolic flexibility

Under conditions of reduced tissue oxygenation, hypoxia-inducible factor (HIF) controls many processes, including angiogenesis and cellular metabolism, and also influences cell proliferation and survival decisions. HIF is centrally involved in tumour growth in inherited diseases that give rise to renal cell carcinoma (RCC), such as Von Hippel–Lindau syndrome and tuberous sclerosis complex. In this study, we examined whether HIF is involved in tumour formation of RCC in Birt–Hogg–Dubé syndrome. For this, we analysed a Birt–Hogg–Dubé patient-derived renal tumour cell line (UOK257) that is devoid of the Birt–Hogg–Dubé protein (BHD) and observed high levels of HIF activity. Knockdown of BHD expression also caused a threefold activation of HIF, which was not as a consequence of more HIF1α or HIF2α protein. Transcription of HIF target genes VEGF, BNIP3 and CCND1 was also increased. We found nuclear localization of HIF1α and increased expression of VEGF, BNIP3 and GLUT1 in a chromophobe carcinoma from a Birt–Hogg–Dubé patient. Our data also reveal that UOK257 cells have high lactate dehydrogenase, pyruvate kinase and 3-hydroxyacyl-CoA dehydrogenase activity. We observed increased expression of pyruvate dehydrogenase kinase 1 (a HIF gene target), which in turn leads to increased phosphorylation and inhibition of pyruvate dehydrogenase. Together with increased protein levels of GLUT1, our data reveal that UOK257 cells favour glycolytic rather than lipid metabolism (a cancer phenomenon termed the ‘Warburg effect’). UOK257 cells also possessed a higher expression level of the L-lactate influx monocarboxylate transporter 1 and consequently utilized L-lactate as a metabolic fuel. As a result of their higher dependency on glycolysis, we were able to selectively inhibit the growth of these UOK257 cells by treatment with 2-deoxyglucose. This work suggests that targeting glycolytic metabolism may be used therapeutically to treat Birt–Hogg–Dubé-associated renal lesions.

Skin changes in oculo-dento-digital dysplasia are correlated with C-terminal truncations of connexin 43†

Oculo‐dento‐digital dysplasia (ODDD, OMIM no.164210) is a pleiotropic disorder caused by mutations in the GJA1 gene that codes for the gap junction protein connexin 43. While the gene is highly expressed in skin, ODDD is usually not associated with skin symptoms. We recently described a family with ODDD and palmoplantar keratoderma. Interestingly, mutation carriers had a novel dinucleotide deletion in the GJA1 gene that resulted in truncation of part of the C‐terminus. We speculated, that truncation of the C‐terminus may be uniquely associated with skin disease in ODDD. Here, we describe a patient with ODDD and palmar hyperkeratosis caused by a novel dinucleotide deletion that truncates most of the connexin 43 C‐terminus. Thus, our findings support the notion that such mutations are associated with the occurrence of skin symptoms in ODDD and provide the first evidence for the existence of a genotype–phenotype correlation.