Cutaneous melanoma occurs in both familial and sporadic forms. We investigated a melanoma-prone family through linkage analysis and high-throughput sequencing and identified a disease-segregating germline mutation in the promoter of the telomerase reverse transcriptase (TERT) gene, which encodes the catalytic subunit of telomerase. The mutation creates a new binding motif for Ets transcription factors and ternary complex factors (TCFs) near the transcription start and, in reporter gene assays, caused up to twofold increase in transcription. We then screened the TERT promoter in sporadic melanoma and observed recurrent ultraviolet signature somatic mutations in 125 of 168 (74%) of human cell lines derived from metastatic melanomas, 45 of 53 corresponding metastatic tumor tissues (85%), and 25 of 77 (33%) primary melanomas. The majority of those mutations occurred at two positions in the TERT promoter and also generated binding motifs for Ets/TCF transcription factors.
The molecular biology of metastatic potential in melanoma has been studied many times previously and changes in the expression of many genes have been linked to metastatic behaviour. What is lacking is a systematic characterization of the regulatory relationships between genes whose expression is related to metastatic potential. Such a characterization would produce a molecular taxonomy for melanoma which could feasibly be used to identify epigenetic mechanisms behind changes in metastatic behaviour. To achieve this we carried out three separate DNA microarray analyses on a total of 86 cultures of melanoma. Significantly, multiple testing correction revealed that previous reports describing correlations of gene expression with activating mutations in BRAF or NRAS were incorrect and that no gene expression patterns correlate with the mutation status of these MAPK pathway components. Instead, we identified three different sample cohorts (A, B and C) and found that these cohorts represent melanoma groups of differing metastatic potential. Cohorts A and B were susceptible to transforming growth factor-beta (TGFbeta)-mediated inhibition of proliferation and had low motility. Cohort C was resistant to TGFbeta and demonstrated high motility. Meta-analysis of the data against previous studies linking gene expression and phenotype confirmed that cohorts A and C represent transcription signatures of weakly and strongly metastatic melanomas, respectively. Gene expression co-regulation suggested that signalling via TGFbeta-type and Wnt/beta-catenin pathways underwent considerable change between cohorts. These results suggest a model for the transition from weakly to strongly metastatic melanomas in which TGFbeta-type signalling upregulates genes expressing vasculogenic/extracellular matrix remodelling factors and Wnt signal inhibitors, coinciding with a downregulation of genes downstream of Wnt signalling.
To identify risk variants for glioma, we conducted a meta-analysis of two genome-wide association studies by genotyping 550K tagging SNPs in a total of 1,878 cases and 3,670 controls, with validation in three additional independent series totaling 2,545 cases and 2,953 controls. We identified five risk loci for glioma at 5p15.33 (rs2736100, TERT; P = 1.50 × 10−17), 8q24.21 (rs4295627, CCDC26; P = 2.34 × 10−18), 9p21.3 (rs4977756, CDKN2A-CDKN2B; P = 7.24 × 10−15), 20q13.33 (rs6010620, RTEL1; P = 2.52 × 10−12) and 11q23.3 (rs498872, PHLDB1; P = 1.07 × 10−8). These data show that common low-penetrance susceptibility alleles contribute to the risk of developing glioma and provide insight into disease causation of this primary brain tumor.
The common sequence variants that have recently been associated with cancer risk are particular to a single, or at most two, cancer types. Following up on our genome-wide scan of basal cell carcinoma1, we identified rs401681(C) on chromosome 5p15.33 satisfying our threshold for genome-wide significance (OR=1.25, P=3.7×10−12). We tested rs401681 for association with sixteen additional cancer types in over 30,000 cancer cases and 45,000 controls and found association with lung cancer (OR=1.15, P=7.2×10−8) and urinary bladder, prostate and cervix cancer (ORs 1.07–1.31, all P<4×10−4). However, rs401681(C) appears to confer protection against cutaneous melanoma (OR=0.88, P=8.0×10−4). Interestingly, most of these cancer types have a strong environmental component to their risk. Investigation of the region led us to rs2736098(A), that showed stronger association with some cancer types. However, neither variant could fully account for the association of the other. Rs2736098 corresponds to A305A in the telomerase reverse transcriptase (TERT) protein while rs401681 is in an intron of the CLPTM1L gene.
We conducted a multi-stage, genome-wide association study (GWAS) of bladder cancer with a primary scan of 589,299 single nucleotide polymorphisms (SNPs) in 3,532 cases and 5,120 controls of European descent (5 studies) followed by a replication strategy, which included 8,381 cases and 48,275 controls (16 studies). In a combined analysis, we identified three new regions associated with bladder cancer on chromosomes 22q13.1, 19q12 and 2q37.1; rs1014971, (P=8×10−12) maps to a non-genic region of chromosome 22q13.1; rs8102137 (P=2×10−11) on 19q12 maps to CCNE1; and rs11892031 (P=1×10−7) maps to the UGT1A cluster on 2q37.1. We confirmed four previous GWAS associations on chromosomes 3q28, 4p16.3, 8q24.21 and 8q24.3, validated previous candidate associations for the GSTM1 deletion (P=4×10−11) and a tag SNP for NAT2 acetylation status (P=4×10−11), as well as demonstrated smoking interactions with both regions. Our findings on common variants associated with bladder cancer risk should provide new insights into mechanisms of carcinogenesis.
The telomerase reverse transcriptase (TERT) promoter, an important element of telomerase expression, has emerged as a target of cancer-specific mutations. Originally described in melanoma, the mutations in TERT promoter have been shown to be common in certain other tumor types that include glioblastoma, hepatocellular carcinoma, and bladder cancer. To fully define the occurrence and effect of the TERT promoter mutations, we investigated tumors from a well-characterized series of 327 patients with urothelial cell carcinoma of bladder. The somatic mutations, mainly at positions −124 and −146 bp from ATG start site that create binding motifs for E-twenty six/ternary complex factors (Ets/TCF), affected 65.4% of the tumors, with even distribution across different stages and grades. Our data showed that a common polymorphism rs2853669, within a preexisting Ets2 binding site in the TERT promoter, acts as a modifier of the effect of the mutations on survival and tumor recurrence. The patients with the mutations showed poor survival in the absence [hazard ratio (HR) 2.19, 95% confidence interval (CI) 1.02-4.70] but not in the presence (HR 0.42, 95% CI 0.18-1.01) of the variant allele of the polymorphism. The mutations in the absence of the variant allele were highly associated with the disease recurrence in patients with Tis, Ta, and T1 tumors (HR 1.85, 95% CI 1.11-3.08). The TERT promoter mutations are the most common somatic lesions in bladder cancer with clinical implications. The association of the mutations with patient survival and disease recurrence, subject to modification by a common polymorphism, can be a unique putative marker with individualized prognostic potential.TERT mutations | cancer genetics | transcription factors | noncoding mutations | reporter assays T he human telomerase reverse transcriptase (TERT) gene encodes the catalytic reverse transcriptase subunit of telomerase that maintains telomere length (1). Increased telomerase activity is perceived to be one of the hallmarks of human cancers, and the transcriptional regulation of the TERT gene is the major cause of its cancer-specific activation (2, 3). The TERT promoter has been shown to be the most important element of telomerase expression because it harbors binding sites for numerous cellular transcriptional activators and repressors that directly or indirectly regulate the gene expression (4). In addition, the high GC content around the transcription start site of the TERT promoter confers epigenetic regulation through methylation and chromatin remodeling (5, 6).We previously described a high-penetrant disease segregating single-nucleotide germ-line mutation in the TERT promoter in a large melanoma family (7). The A > C (T > G) mutation at position −57 bp (from the ATG start site; Chr 5:1295161 hg19 coordinate) resulted in creation of a new binding motif GGAA/T for E-twenty six (Ets) transcription factors and a general binding CCGGAA/T motif for ternary complex factors (TCF) (8). Simultaneous screening of the TERT promoter for somatic mutations...
Fair color increases risk of cutaneous melanoma (CM) and basal cell carcinoma (BCC). Recent genome-wide association studies have identified variants affecting hair, eye and skin pigmentation in Europeans. Here, we assess the effect of these variants on risk of CM and BCC in European populations comprising 2,121 individuals with CM, 2,163 individuals with BCC and over 40,000 controls. A haplotype near ASIP, known to affect a similar spectrum of pigmentation traits as MC1R variants, conferred significant risk of CM (odds ratio (OR) = 1.45, P = 1.2 x 10(-9)) and BCC (OR = 1.33, P = 1.2 x 10(-6)). The variant in TYR encoding the R402Q amino acid substitution, previously shown to affect eye color and tanning response, conferred risk of CM (OR = 1.21, P = 2.8 x 10(-7)) and BCC (OR = 1.14, P = 6.1 x 10(-4)). An eye color variant in TYRP1 was associated with risk of CM (OR = 1.15, P = 4.6 x 10(-4)). The association of all three variants is robust with respect to adjustment for the effect of pigmentation.
We conducted a genome wide SNP association study on 1,803 Urinary Bladder Cancer (UBC) cases and 34,336 controls from Iceland and the Netherlands and follow up studies in seven additional case control groups (2,165 cases and 3,800 controls). The strongest association was observed with allele T of rs9642880 on chromosome 8q24, 30kb upstream of the c-Myc gene (allele specific OR=1.22; P=9.34×10−12). Approximately 20% of individuals of European ancestry are homozygous for rs9642880 (T) and their estimated risk of developing UBC is 1.49 times that of non-carriers with population attributable risk (PAR) of 17%. No association was observed between UBC and the four 8q24 variants previously associated with prostate, colorectal and breast cancers, nor did rs9642880 associate with any of these three cancers. A weaker signal, but nonetheless of genome wide significance, was captured by rs710521 (A) located near the TP63 gene on chromosome 3q28 (allele specific OR=1.19; P=1. 15× 10−7).
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