Fig. 3

Apolipoprotein B mRNA-editing enzyme catalytic polypeptide–like (APOBEC) mutation signatures are sharply enhanced in a squamous cell carcinoma (SCC) arising in a clinical context of nasal septal injury. Column graph shows percentage of mutations matching each of three stereotyped patterns (“signatures”) [3, 4] of nucleotide mutation and context. Catalogue of Somatic Mutations in Cancer (COSMIC) signatures 2 and 13 (36%) are associated with APOBEC mutagenesis and are detected on average at levels <5% in spontaneous, ultraviolet (UV)-derived cutaneous SCCs. COSMIC signature 4 is associated with UV light exposure and mutagenesis. COSMIC signature 5 represents a less specific mutagenesis pattern found in many cancer types (clock-like) and associated with normal aging, as well as chronic tissue injury [3]. p values show results of a one-way analysis of variance assessing whether the prevalence of a mutation signature is significantly different in the patient’s tumor (red) compared to a cohort of 38 UV-induced SCCs (blue) and 279 The Cancer Genome Atlas (TCGA) head-and-neck SCCs (green). This analysis demonstrated a significant overrepresentation of the APOBEC signature (p = 0.000) and underrepresentation of the tobacco signature (p = 0.001) in our patient’s tumor, compared to the reference data set. Mutational signature assignation from exome sequencing data was performed using the deconstructSigs method [5]