Biomedical subjects

C Wicking

Publications and source records attributed to C Wicking.

At least 19 recordsLinked to original sources

PubMed1999

Isolation and characterization of human patched 2 (PTCH2), a putative tumour suppressor gene inbasal cell carcinoma and medulloblastoma on chromosome 1p32.

Mutations of the human Patched gene ( PTCH ) have been identified in individuals with the nevoid basal cell carcinoma syndrome (NBCCS) as well as in sporadic basal cell carcinomas and medulloblastomas. We have isolated a homologue of this tumour suppressor gene and localized it to the short arm of chromosome 1 (1p32.1-32.3). Patched 2 ( PTCH2 ) comprises 22 coding exons and spans approximately 15 kb of genomic DNA. The gene encodes a 1203 amino acid putative transmembrane protein which is highly homologous to the PTCH product. We have characterized the genomic structure of PTCH2 and have used single-stranded conformational polymorphism analysis to search for mutations in PTCH2 in NBCCS patients, basal cell carcinomas and in medulloblastomas. To date, we have identified one truncating mutation in a medulloblastoma and a change in a splice donor site in a basal cell carcinoma, suggesting that the gene plays a role in the development of some tumours.

Amino Acid Sequence↗

PubMed1998

CDX2, a human homologue of Drosophila caudal, is mutated in both alleles in a replication error positive colorectal cancer.

The Cdx2 gene is one of three murine homologues of the Drosophila homeobox gene caudal. Mice heterozygous for a null mutation in Cdx2 exhibit a variable phenotype including tail abnormalities, stunted growth and a homeotic shift of vertebrae. Most strikingly, however, 90% of heterozygous mice were reported to develop multiple intestinal adenomatous polyps, most notably in the proximal colon (Chawengsaksophak et al., 1997). These observations led us to propose that mutation of CDX2 may be involved in the genesis of some human colorectal tumours. A survey of DNA from 85 colorectal tumours revealed that one with extensive microsatellite instability (RER+ phenotype) has mutations in both alleles of CDX2. Both mutations occur in coding regions which contain repetitive elements and are consistent with those found in RER + tumours.

Adenocarcinoma↗

PubMed1998

No evidence for the H133Y mutation in SONIC HEDGEHOG in a collection of common tumour types.

The human homologue of the Drosophila segment polarity gene patched is mutated in the cancer predisposition syndrome naevoid basal cell carcinoma syndrome (NBCCS), as well as in several types of tumour associated with the disorder. It was recently reported that a single recurrent mutation in the SONIC HEDGEHOG gene, which encodes the PATCHED ligand, was found in one of 43 basal cell carcinomas (BCCs), one of 14 medulloblastomas and one of six breast carcinomas analysed (Oro et al., 1997). We have searched extensively for this same mutation in a large collection of BCCs, medulloblastomas and carcinomas of the breast, ovary and colorectum and have failed to detect the mutation in any sample analysed.

Adolescent↗

PubMed1998

The effects of splice site mutations in patients with naevoid basal cell carcinoma syndrome.

We have previously identified the human homologue of the Drosophila patched gene and have described, in this gene, mutations that give rise to naevoid basal cell carcinoma syndrome (NBCCS). Here, we have analysed the effects of three splice site mutations within human PATCHED (PTCH) by the reverse transcription/polymerase chain reaction method in cultured patient lymphocyte cell lines. Two alterations, a point mutation in intron 7 and an insertion in intron 10, lead to premature truncation of the PATCHED protein. Another point mutation in intron 17 results in the skipping of exon 18 and the subsequent in-frame deletion of 46 amino acids. Additionally, in all lymphocyte and keratinocyte cell lines examined, exon 10 of PTCH is alternatively spliced leading to an in-frame deletion of 52 amino acids.

Alternative Splicing↗

PubMed1997

De novo mutations of the Patched gene in nevoid basal cell carcinoma syndrome help to define the clinical phenotype.

The demonstration that mutations in the Patched (PTCH) gene cause nevoid basal cell carcinoma syndrome (NBCCS) has led to the identification of the exact molecular lesion in a percentage of individuals with the syndrome. In addition, it has been possible to determine, through molecular analysis of parents and other relatives of these individuals, if the mutation is inherited or has arisen de novo. We have previously reported 28 mutations in individuals with NBCCS, and here we present an additional 4 novel mutations. We have also analyzed relatives of a number of the individuals in whom we have found mutations. In total we have identified 8 individuals who carry a de novo mutation in the PTCH gene. In 5 of these cases, clinical and radiological examination had not unequivocally ruled out a diagnosis in one of the parents. This helps to define the clinical phenotype and suggests that diagnostic criteria in this complex syndrome may require review.

Basal Cell Nevus Syndrome↗

PubMed1997

Medulloblastomas of the desmoplastic variant carry mutations of the human homologue of Drosophila patched.

Inactivating mutations in the PTCH gene, a human homologue of the Drosophila segment polarity gene patched, have been identified recently in patients with nevoid basal cell carcinoma syndrome. These patients are predisposed to various neoplasias including basal cell carcinomas and medulloblastomas (MBs). To determine the involvement of PTCH in sporadic MBs, which represent the most frequent malignant brain tumors in children, we screened for PTCH alterations in an unselected panel of 64 biopsy samples from 62 patients and four continuous MB cell lines, all derived from patients with sporadic MBs. Using single-strand conformational polymorphism analysis, we screened exons 2-22 and detected nonconservative PTCH mutations in 3 of 11 samples from sporadic cases of the desmoplastic variant of MB but none in 57 MBs with classical (nondesmoplastic) histology. In two of the tumors with mutations and in two additional desmoplastic cases, loss of heterozygosity was found at 9q22. These findings suggest that PTCH represents a tumor suppressor gene involved in the development of the desmoplastic variant of MB.

Adolescent↗

PubMed1997

Characterisation of human patched germ line mutations in naevoid basal cell carcinoma syndrome.

Mutations in the human patched gene have recently been detected in patients with naevoid basal cell carcinoma syndrome. We have characterised a further 5 novel germ line mutations in patients presenting with multiple odontogenic keratocysts. Four mutations cause premature stop codons and one mutation results in an amino-acid substitution towards the carboxyl terminus of the predicted patched protein. No obvious genotype-phenotype correlations could be interpreted, consistent with previous studies.

Adolescent↗

PubMed1997

Mapping the multiple self-healing squamous epithelioma (MSSE) gene and investigation of xeroderma pigmentosum group A (XPA) and PATCHED (PTCH) as candidate genes.

The MSSE gene predisposes to the development of multiple invasive but self-healing skin tumours (multiple self-healing squamous epitheliomata, MSSE). MSSE (previously named ESS1) was mapped to chromosome 9q by linkage analysis; haplotype analysis in families then suggested a common founder mutation and indicated that the gene lies in the interval D9S1-D9S29 (9q22-q31). Squamous cell carcinomata also develop as one of the complications of xeroderma pigmentosum, and one of the xeroderma pigmentosum genes (XPA) maps within the MSSE interval. We have investigated the hypothesis that a novel dominant mutation in XPA is responsible for MSSE. We screened the entire coding region, 3' untranslated region (UTR) and 5'UTR of XPA for germline mutations in MSSE families by single-stranded conformation polymorphism analysis and by direct DNA sequencing. No mutations were detected but a novel intragenic polymorphism was identified in the 5'UTR of XPA, in both MSSE-affected and unrelated normal individuals. This XPA polymorphism and nine new polymorphic markers that map in the MSSE region were typed in eleven MSSE families; XPA was excluded as the MSSE gene and the most likely location of MSSE was reduced to the interval between D9S197 and (D9S287, D9S1809). The Patched (PTCH) gene, which is mutated in naevoid basal cell carcinoma syndrome (NBCCS or Gorlin syndrome) lies in this interval and all MSSE families have been shown to share a common haplotype at three novel intragenic PTCH polymorphisms. Although no mutation has been detected in MSSE families, PTCH has not been excluded as the MSSE gene.

Basal Cell Nevus Syndrome↗

PubMed1997

Molecular basis of the nevoid basal cell carcinoma syndrome.

Many genes originally identified because of their role in embryonic development are also important in control of cell growth and differentiation postnatally. Mutations in some of these genes have been shown to contribute to carcinogenesis. The nevoid basal cell carcinoma syndrome is an autosomal dominant disorder that predisposes to basal cell carcinomas of the skin as well as widespread developmental defects. The gene for this disorder, NBCCS, maps to chromosome 9q22.3, and loss of heterozygosity at this site in both sporadic and hereditary basal cell carcinomas suggests that it functions as a tumor suppressor. NBCCS was positionally cloned and shown to be the human homologue of the Drosophila gene, patched. Drosophila patched is part of the hedgehog signaling pathway, important in determining embryonic patterning and cell fate in multiple structures of the developing embryo. That mutations in human patched result in dysregulation of several genes known to play a role in both organogenesis and carcinogenesis may explain both the birth defects and the cancer predisposition seen in the nevoid basal cell carcinoma syndrome.

Animals↗

PubMed1997

Pulsed-field gel electrophoresis and FISH mapping of chromosome 9q22: placement of a novel zinc finger gene within the NBCCS and ESS1 region.

Chromosome 9q22 is a gene-rich region to which several human disease loci have been mapped. Pulsed field gel electrophoresis (PFGE) and FISH were used to determine the order of and distance between 12 chromosome 9q22 markers flanked by D9S196 and D9S180. D9S780 and XPA were within 190 kb of each other and hybridized to the same 460-kb NotI fragment as D9S180. ZNF169, a novel kruppel-type gene, and D9S280 shared several PFGE fragments indicating that they are not more than 300 kb apart. Interphase FISH showed that COL15A1 lies distal to the region bounded by D9S180 and D9S196 and that ZNF169 is adjacent to D9S196. Based on the restriction fragment lengths in this region and estimates from FISH, the distance from D9S180 to D9S196 is not less than 2 Mb.

Basal Cell Nevus Syndrome↗

PubMed1997

Most germ-line mutations in the nevoid basal cell carcinoma syndrome lead to a premature termination of the PATCHED protein, and no genotype-phenotype correlations are evident.

The human homologue of the Drosophila segment polarity gene patched is implicated in the development of nevoid basal cell carcinoma syndrome (NBCCS) and in the genesis of sporadic basal cell carcinomas. In order to examine the phenotypic variability in NBCCS and to highlight functionally important domains of the PTCH protein, we have now screened 71 unrelated NBCCS individuals for mutations in the PTCH exons. We identified 28 mutations that are distributed throughout the entire gene, and most (86%) cause protein truncation. As part of this analysis, we demonstrate that failure of one NBCCS family to show clear linkage to chromosome 9q22.3-31 is most likely due to germinal mosaicism. We have identified three families bearing identical mutations with variable phenotypes, suggesting phenotypic variability in NBCCS is a complex genetic event. No phenotype genotype correlation between the position of truncation mutations and major clinical features was evident. Two missense mutations have been identified, and their location within transmembrane domains supports the notion that PTCH may have a transport function. The preponderance of truncation mutants in the germ line of NBCCS patients suggests that the developmental defects associated with the disorder are most likely due to haploinsufficiency.

Basal Cell Nevus Syndrome↗

PubMed1996

Mutations of the human homolog of Drosophila patched in the nevoid basal cell carcinoma syndrome.

The nevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant disorder characterized by multiple basal cell carcinomas (BCCs), pits of the palms and soles, jaw keratocysts, a variety of other tumors, and developmental abnormalities. NBCCS maps to chromosome 9q22.3. Familial and sporadic BCCs display loss of heterozygosity in this region, consistent with the gene being a tumor suppressor. A human sequence (PTC) with strong homology to the Drosophila segment polarity gene, patched, was isolated from a YAC and cosmid contig of the NBCCS region. Mutation analysis revealed alterations of PTC in NBCCS patients and in related tumors. We propose that a reduction in expression of the patched gene can lead to the developmental abnormalities observed in the syndrome and that complete loss of patched function contributes to transformation of certain cell types.

Alleles↗

PubMed1996

A mammalian patched homolog is expressed in target tissues of sonic hedgehog and maps to a region associated with developmental abnormalities.

Drosophila patched is a segment polarity gene required for the correct patterning of larval segments and imaginal discs during fly development and has a close functional relationship with hedgehog. We have isolated a complete human PATCHED cDNA sequence, which encodes a putative protein of 1296 amino acids, and displays 39% identity and 60% similarity to the Drosophila PATCHED protein. Hydropathy analysis suggests that human PATCHED is an integral membrane protein with a pattern of hydrophobic and hydrophilic stretches nearly identical to that of Drosophila patched. In the developing mouse embryo, patched is initially detected within the ventral neural tube and later in the somites and limb buds. Expression in the limb buds is restricted to the posterior ectoderm surrounding the zone of polarizing activity. The results show that patched is expressed in target tissues of sonic hedgehog, a murine homolog of Drosophila hedgehog suggesting that patched/hedgehog interactions have been conserved during evolution. Human PATCHED maps to human chromosome 9q22.3, the candidate region for the nevoid basal cell carcinoma syndrome. Patched expression is compatible with the congenital defects observed in the nevoid basal cell carcinoma syndrome.

Amino Acid Sequence↗

PubMed1996

+P5 (D1S3309E), a novel target binding site for the Wilms' tumour suppressor 1 (WT1) gene, maps to human chromosome 1q21-->22.

The Wilms' tumor suppressor 1 gene (WT1) encodes a zinc finger transcription factor critical for normal urogenital development. We have previously isolated a DNA fragment, +P5 (D1S3309E), to which all WT1 protein isoforms bind. Using PCR of a human x rodent somatic cell hybrid mapping panel, together with two-color fluorescence in situ hybridisation of +P5-containing cosmids and previously localised human chromosome 1q cosmids, we have mapped the +P5 fragment to chromosome 1q21-->q22.

Animals↗

PubMed1995

Fine deletion mapping on the long arm of chromosome 9 in sporadic and familial basal cell carcinomas.

Basal cell carcinomas (BCCs) are the most common sporadic cancers worldwide. They are also a cardinal manifestation of a familial cancer predisposition syndrome, naevoid BCC syndrome (NBCCS). The gene responsible for NBCCS is likely to be a tumour suppressor gene and has been genetically mapped to a 2cM region between microsatellite markers, D9S196 and D9S180 at 9q22.3-q31. 101 BCCs (63 sporadic and 38 familial) were examined for loss of heterozygosity (LOH) in the candidate region of the NBCCS gene. Deletions were found in 46% and all LOH is consistent with genetic mapping of the NBCC locus. These findings strongly support the hypothesis that inactivation of the putative tumour suppressor, the NBCCS gene, is important in the formation of sporadic BCCs. One sporadic tumour indicates that the smallest region of overlap of these deletions is within the interval between D9S287 and D9S180. If this is confirmed in additional tumours, it would further narrow down the NBCCS region and exclude one candidate gene, that for the C complementation group of Fanconi anaemia, which maps proximally to D9S287. However, it would not exclude another candidate, the gene for the A complementation group of xeroderma pigmentosum (XPAC). Evidence of imprinting was also sought but preliminary data indicate that it is unlikely to occur at the NBCCS locus.

Adult↗

PubMed1995

The human growth-arrest-specific gene GAS1 maps outside the candidate region of the gene for nevoid basal cell carcinoma syndrome.

The human growth-arrest specific gene GAS1 maps to chromosome bands 9q21.3-->q22, the region known to contain the tumour suppressor gene responsible for nevoid basal cell carcinoma syndrome (NBCCS). Because of its putative action as a tumour suppressor gene, the GAS1 gene was analysed as a candidate for the NBCCS gene. Using two-colour fluorescence in situ hybridization, the GAS1 gene maps outside the interval which, by genetic analysis, has been shown to contain the NBCCS gene.

Animals↗

PubMed1994

Nevoid basal cell carcinoma syndrome: review of 118 affected individuals.

One hundred eighteen cases of nevoid basal cell carcinoma syndrome (NBCCS, Gorlin's syndrome or basal cell nevus syndrome) are presented in this study. In aiming to ascertain all the affected families in Australia, we have examined the largest series to date. Relative frequencies of associated complications are presented and compared with those of the recent English survey by Evans et al. [J Med Genet 30:460-464, 1993]. The frequencies of most manifestations are similar. However, one major difference is that the multiple basal cell carcinomas are manifest from an earlier age in the Australian population, which probably reflects greater exposure to ultraviolet radiation. Of the 64 families ascertained, 37 represented simplex cases, and, accordingly, the apparent new mutation rate is surprisingly high (14-81%) given the lack of impact of NBCCS on reproductive capabilities. There is some evidence to suggest that this may be attributable to anticipation.

Abnormalities, Multiple↗

PubMed1994

Fine genetic mapping of the gene for nevoid basal cell carcinoma syndrome.

Nevoid basal cell carcinoma syndrome (NBCCS, or Gorlin syndrome) is a cancer predisposition syndrome characterized by multiple basal cell carcinomas and diverse developmental defects. The gene responsible for NBCCS, which is most likely to be a tumor suppressor gene, has previously been mapped to 9q22.3-q31 in a 12-cM interval between the microsatellite marker loci D9S12.1 and D9S109. Combined multipoint and haplotype analyses of additional polymorphisms in this region in our collection of Australasian pedigrees have further refined the localization of the gene to between the markers D9S196 and D9S180, an interval reported to be approximately 2 cM.

Adult↗