A highly recurrent RPS27 5'UTR mutation in melanoma

Abstract

The incidence of melanoma continues to rise globally and is increasing at a rate greater than any other cancer. To systematically search for new genes involved in melanomagenesis, we collated exome sequencing data from independent melanoma cohort datasets, including those in the public domain. We identified recurrent mutations that may drive melanoma growth, survival or metastasis, and which may hold promise for the design of novel therapies to treat melanoma. These included a frequent recurrent (i.e. hotspot) mutation in the 5' untranslated region of RPS27 in ~10% of samples. We show that the mutation expands the 5'TOP element, a motif known to regulate the expression of most of the ribosomal protein family, to which RPS27 belongs, and thus might sensitize the mutated transcript to growth-mediated regulation. This finding highlights not only the important role of non-protein coding genetic aberrations in cancer development but also their potential as novel therapeutic targets.

Figure 1. The RPS27 recurrent mutation alters the transcription starting site (TSS) of the RPS27 gene

A. Description of the genomic sequence flanking the recurrent mutation of the RPS27 gene. The 5'TOP element sequence is underlined. To determine the effect of the C > T recurrent mutation on the TSS of the RPS27 gene, RACE analysis was performed using the RNA linker described in B. cDNA was prepared from the ligated mRNA and amplified using a Forward primer located in the linker and a RPS27 specific Reverse primer. The amplified products were cloned in pGEM-T easy vector. Colonies were picked and sequenced. A representative chromatography and the genomic sequence of the 5' terminus of the transcripts is described in C. The 5'TOP element is underlined, the TSS is designated with arrows and the C > T substitution is highlighted with red. WT: wild-type; mut: mutant.