Overproduction of DNA repair gene EXO1 found to create aberrant DNA cutting linked to cancer

A study reported by ScienceDaily on 19 June 2026 describes how EXO1, a gene whose protein product normally functions as a nuclease in DNA repair pathways, can become pathological when expressed at elevated levels. Under normal conditions, EXO1 contributes to the repair of damaged DNA by trimming back broken strand ends; however, researchers found that when cells overproduce the EXO1 protein, it begins to cut DNA at sites it should not, generating damage rather than resolving it.

The finding exposes a potential cancer-associated vulnerability. Because some tumour cells are known to upregulate DNA repair genes as part of broader transcriptional dysregulation, the work raises the possibility that EXO1 overexpression could be a targetable feature of certain cancers — a class of aberrant behaviour sometimes described as 'oncogene addiction to repair factors'. The specific cancer types implicated and the experimental model system used are not detailed in the available ScienceDaily lede; readers should consult the primary publication for full context.

The result sits within a well-established tradition of research showing that genes with protective functions under normal stoichiometric conditions can generate harm when dosage is perturbed. Prior work on other nucleases — including MRE11 and DNA2 — has demonstrated similar dose-dependent switches between repair and damage. The original research institution and journal were not identified from available feed information.