The increasing availability of large‐scale whole cancer genome sequencing data sets has enabled research efforts to focus on cancer driver mutations within the noncoding genome.
cis
‐Regulatory elements are sites responsible for the control of gene expression. Mutations at such loci may modify transcription factor binding sites, disrupt enhancer–promoter interactions or affect epigenetic marks.
cis
‐Regulatory driver mutations have been found in some cancer types to‐date, with initial discoveries of point mutations in the
TERT
promoter, small insertions creating an enhancer regulating
TAL1
and genomic rearrangements leading to simultaneous enhancer dysregulation of
EVI1
and
GATA2
. However, recent discoveries have also revealed mechanisms responsible for the accumulation of recurrent, and even functional, somatic single‐nucleotide mutations in regulatory regions, wholly apart from selective pressure. Close scrutiny of candidate
cis
‐regulatory mutations is necessary in order to effectively identify mutations that have undergone positive selection and to accurately distinguish driver from passenger mutations.
Key Concepts
Improvements in DNA sequencing technology, and the commencement of large‐scale cancer genome sequencing projects, have made discoveries in the noncoding genome possible.
cis
‐Regulatory elements, such as promoters and enhancers, are responsible for the control of gene expression.
Transcription factors bind to
cis
‐regulatory elements, influencing the rate of transcription of DNA to mRNA.
Mutations in
cis
‐regulatory elements can drive cancer development by altering transcription factor binding sites, enhancer–promoter interactions or the epigenetic landscape of the cell.
Alterations to
cis
‐regulatory elements can lead to gene dysregulation, potentially impacting the expression of oncogenes or tumour suppressor genes.
Recurrent somatic driver mutations affecting
cis
‐regulatory elements have already been identified in cancer genomes, including point mutations, insertions and deletions (indels) and structural rearrangements.
cis
‐Regulatory elements may appear recurrently mutated in cancer due to selective pressures or due to other mechanisms driving the formation of mutation hot spots.
Transcription factor binding can inhibit access to nucleotide excision repair (NER) enzymes, leading to increased mutation rates at transcription factor binding sites in some cancers.
DNA modifications and nucleotide composition can both influence the propensity for certain sites to become mutated.
Close scrutiny of candidate
cis
‐regulatory mutations is necessary in order to effectively identify sites under selective pressure and to accurately distinguish driver from passenger mutations.