Somatic mosaicism containing double mutations in PTCH1 revealed by generation of induced pluripotent stem cells from nevoid basal cell carcinoma syndrome.

BACKGROUND: Nevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant disorder characterised by developmental defects and tumorigenesis, such as medulloblastomas and basal cell carcinomas, caused by mutations of the patched-1 (PTCH1) gene. In this article, we seek to demonstrate a mosaicism containing double mutations in PTCH1 in an individual with NBCCS. METHODS AND RESULTS: A de novo germline mutation of PTCH1 (c.272delG) was detected in a 31-year-old woman with NBCCS. Gene analysis of two out of four induced pluripotent stem cell (iPSC) clones established from the patient unexpectedly revealed an additional mutation, c.274delT. Deep sequencing confirmed a low-prevalence somatic mutation (5.5%-15.6% depending on the tissue) identical to the one found in iPSC clones. CONCLUSIONS: This is the first case of mosaicism unequivocally demonstrated in NBCCS. Furthermore, the mosaicism is unique in that the patient carries one normal and two mutant alleles. Because these mutations are located in close proximity, reversion error is likely to be involved in this event rather than a spontaneous mutation. In addition, this study indicates that gene analysis of iPSC clones can contribute to the detection of mosaicism containing a minor population carrying a second mutation.

Nevoid basal cell carcinoma syndrome caused by splicing mutations in the PTCH1 gene.

Nevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant disorder characterized by developmental defects and tumorigenesis such as medulloblastomas and basal cell carcinomas, caused by mutations of the patched-1 (PTCH1) gene. To date, we have detected 73 mutations in PTCH1 and ten of them (14 %) were suspected splicing mutations. Eight out of the ten mutations were localized near the splice donor site. Five mutations were localized within the invariant GT-AG splice site, whereas the other five mutations occurred outside the invariant GT-AG site including the last exonic nucleotide. When the transcripts were examined, all mutations resulted in aberrant splicing, including exon skipping or the activation of cryptic splice sites. This is the first extensive report of NBCCS focusing on splice site mutations, and it highlights the importance of analyzing transcripts especially for mutations lying outside the GT-AG splicing consensus site. In addition, the splice site score calculated by Splice-Site Analyzer Tool provided by Tel Aviv University helped predict aberrant splice patterns in most of the cases.

Selective haploinsufficiency of longer isoforms of PTCH1 protein can cause nevoid basal cell carcinoma syndrome.

Nevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant disorder characterized by developmental defects and tumorigenesis. The gene responsible for NBCCS is PTCH1. The PTCH1 gene has five alternatively used first exons resulting in the translation of three isoforms of the PTCH1 protein; that is, PTCHL, PTCHM and PTCHS. However, the biological significance of each isoform is unclear. Here we show an individual with NBCCS carrying a nonsense mutation in PTCH1 exon2, c.387G>A (p.W129X). As the mutation lay upstream of the ATG codon used for PTCHS translation, the mutant allele still expressed RNA isoforms that encode PTCHS. These results clearly demonstrate that a selective haploinsufficiency of longer isoforms of the PTCH1 protein, PTCHL and PTCHM, but not PTCHS is sufficient to cause NBCCS. Although mice selectively deficient in PTCHS isoforms are currently unavailable, this study sheds light on the complex in vivo roles of PTCH1 isoforms.

Nevoid basal cell carcinoma syndrome with cleft lip and palate associated with the novel PTCH gene mutations.

Nevoid basal cell carcinoma syndrome (NBCCS) is a rare autosomal dominant disorder characterized by developmental abnormalities and a predisposition to cancers. Two unrelated patients, 21- and 16-year-old males, with cleft lip and palate and multiple jaw cysts, were diagnosed according to clinical criteria. To confirm a diagnosis of NBCCS, we undertook a molecular genetic analysis of the PTCH gene. Their PTCH genes were analyzed by direct sequencing of the PCR product from their DNA, and previously unreported mutations were identified. A heterozygous duplication at the nucleotide position between 3325 and 3328 of the PTCH gene (c.3325_3328dupGGCG) was detected in the 21-year-old patient. It caused a frameshift mutation, resulting in a premature termination of the PTCH protein. A point mutation (G to C) in intron 7 of the PTCH gene (c.1067+1G>C) was detected in the 16-year-old patient. This caused an aberrant splicing of PTCH. It is interesting to note that the non-canonical cryptic splice-donor site was activated, which did not conform to the GT-AG rule.

Changes in serum IgG oligosaccharide chains with prostate cancer progression.

BACKGROUND: Changes of serum IgG oligosaccharide chain structure have been found in B cell lineage tumors and autoimmune diseases. Currently, the cancer-associated carbohydrate epitopes CA72-4 and CA15-3 are used as serum tumor markers. In the present study, we analyzed the structure of serum IgG oligosaccharide chains in prostate cancer (PCa) patients using the simple new method of fluorophore-associated carbohydrate electrophoresis (FACE). We also evaluated the relationship between changes of serum IgG oligosaccharide chain structure and serum concentration of prostate-specific antigen (PSA). MATERIALS AND METHODS: The structure of serum IgG oligosaccharide chains from 12 PCa patients (6 localized cancer, 6 metastatic cancer) and 10 healthy controls was evaluated by FACE. PSA levels in serum were determined by enzyme immunoassay. RESULTS: Fr 1 (monogalactosyl oligosaccharide) and Fr 2 (digalactosyl oligosaccharide) decreased significantly (p<0.05), while Fr 4 (agalactosyl IgG oligosaccharide) increased with PCa tumorprogression. The Fr 4/Fr 1+2 ratio in metastatic PCa patients was significantly higher than in healthy controls (p<0.05), and there was a significant correlation (r=0.84, p<0.05) between serum PSA levels and the Fr 4/Fr 1+2 ratio in all patients with PCa. CONCLUSION: The changes of serum IgG oligosaccharide chain structure with PCa progression are based on the abnormality of glycosylation in PCa metastasis. Therefore, the analysis of serum IgG oligosaccharide chain structure by FACE may be an auxiliary indicator of PSA for monitoring PCa progression.

Analysis of the oligosaccharide chain of human serum immunoglobulin g in patients with localized or metastatic cancer.

A quantitative imbalance between matrix metalloproteinases produced by cancer cells and tissue inhibitors of metalloproteinases produced by fibroblasts and other types of cells has been demonstrated to be a causative factor in invasion and metastasis of cancer cells. On the other hand, it is reported that sugar chains of adhesion molecules such as integrins and CD44 also influence the metastasis of cancer cells. Here, alterations of serum IgG oligosaccharide chain structure were investigated during tumor progression using the new method of fluorophore-assisted carbohydrate electrophoresis (FACE). The structure of serum IgG oligosaccharide chains from 22 cancer patients (11 localized cancer, 11 metastatic cancer) and 10 healthy controls was evaluated by FACE. It was clearly demonstrated that serum IgG oligosaccharide chains without galactose (agalactosyl IgG oligosaccharide) significantly increased with tumor progression of lung and gastric cancers. It is concluded that a marked increase of agalactosyl IgG oligosaccharide in these cancer patients is associated with carcinogenesis and metastasis. Therefore, the analysis of serum IgG oligosaccharide chain structure by FACE may be useful for evaluating diagnosis and prognosis in patients with these carcinomas.