Aquino, J. D. | Search bioRxiv

bioRxiv2026

WRN deficiency generates oncogenic rearrangements at TA-rich tandem repeats

Werner syndrome, a premature-aging disorder caused by inherited loss of the WRN helicase, predisposes to a narrow set of cancers, including melanoma and sarcoma, through mechanisms that have been unclear. WRN resolves the secondary structures that TA-dinucleotide repeats form, a role established for the expanded repeats of mismatch-repair-deficient cancers. We show that WRN loss also destabilizes native, unexpanded TA-rich tandem repeats, which become fragile sites where chromosomes break and rearrange. In melanoma these rearrangements recurrently produce an identical 15.7Mb-long deletion that transcriptionally activates TERT, the earliest driver of these tumors, and separately disrupt tumor suppressors such as CDKN2A/B and NF1. The same class of rearrangement occurs in WRN-deficient cancers of other types. WRN deficiency is thus a source of instability at TA-rich tandem repeats that generates oncogenic rearrangements.

cancer biology↗

bioRxiv2023

The genetic evolution of acral melanoma

Acral melanoma is an aggressive type of melanoma with unknown origins, arising on the sole, palm, or nail apparatus. It is the most common type of melanoma in individuals with dark skin and is notoriously challenging to treat. Our study examined exome sequencing data from 139 tissue samples, spanning different progression stages, collected from 37 patients. We found that 78.4% of the melanomas displayed one or more clustered copy number transitions with focal amplifications, recurring predominantly on chromosomes 5, 11, 12, and 22. These genomic "hailstorms" were typically shared across all progression stages within individual patients. Genetic alterations known to activate TERT also arose early. By contrast, mutations in the MAP- kinase pathway appeared later during progression, often leading to different tumor areas harboring non-overlapping driver mutations. We conclude that the evolutionary trajectories of acral melanomas substantially diverge from those of melanomas on sun-exposed skin, where MAP-kinase pathway activation initiates the neoplastic cascade followed by immortalization later. The punctuated formation of hailstorms, paired with early TERT activation, suggests a unique mutational mechanism underlying the origins of acral melanoma. Our findings highlight an essential role for telomerase, likely in re-stabilizing tumor genomes after hailstorms have initiated the tumors. The marked genetic heterogeneity, in particular of MAP-kinase pathway drivers, may partly explain the limited success of targeted and other therapies in treating this melanoma subtype.

cancer biology↗