Highly recurrent TERT promoter mutations in human melanoma

Abstract

Systematic sequencing of human cancer genomes has identified many recurrent mutations in the protein-coding regions of genes but rarely in gene regulatory regions. Here, we describe two independent mutations within the core promoter of telomerase reverse transcriptase (TERT), the gene coding for the catalytic subunit of telomerase, which collectively occur in 50 of 70 (71%) melanomas examined. These mutations generate de novo consensus binding motifs for E-twenty-six (ETS) transcription factors, and in reporter assays, the mutations increased transcriptional activity from the TERT promoter by two- to fourfold. Examination of 150 cancer cell lines derived from diverse tumor types revealed the same mutations in 24 cases (16%), with preliminary evidence of elevated frequency in bladder and hepatocellular cancer cells. Thus, somatic mutations in regulatory regions of the genome may represent an important tumorigenic mechanism.

Fig. 1. Identification of TERT promoter mutations in melanoma and cancer cell lines

(A) Sequence chromatograms of matched tumor and normal DNA representing somatic mutations chr 5: 1,295,228 C>T (C228T) and chr 5: 1,295,250 C>T (C250T) in the TERT promoter locus. (B) Pie chart of C228T and C250T somatic mutation status in 70 surveyed melanoma tumors and short-term cultures. Sum of percentages is greater than 100% due to rounding. (C) Luciferase reporter assays for transcriptional activity from the TERT core promoter (−200 to +73) with either the C228T or C250T mutation compared to wild-type promoter in A375, RPMI-7951, UACC-62, T24 or HepG2 cell lines. The results depicted are the average of at least 3 independent experiments. Values are mean ± s.d. * P < 0.05. (D) Bar plot of 150 cancer cell lines of the Cancer Cell Line Encyclopedia (3) depicting TERT promoter mutation status. Individual bars represent the total number of cell lines of a given tumor type interrogated for C228T and C250T mutations, with mutation status indicated by colors defined in the legend.