The NEIL1 G83D germline DNA glycosylase variant induces genomic instability and cellular transformation

Abstract

Base excision repair (BER) is a key genome maintenance pathway. The NEIL1 DNA glycosylase recognizes oxidized bases, and likely removes damage in advance of the replication fork. The rs5745906 SNP of the NEIL1 gene is a rare human germline variant that encodes the NEIL1 G83D protein, which is devoid of DNA glycosylase activity. Here we show that expression of G83D NEIL1 in MCF10A immortalized but non-transformed mammary epithelial cells leads to replication fork stress. Upon treatment with hydrogen peroxide, we observe increased levels of stalled replication forks in cells expressing G83D NEIL1 versus cells expressing the wild-type (WT) protein. Double-strand breaks (DSBs) arise in G83D-expressing cells during the S and G2/M phases of the cell cycle. Interestingly, these breaks result in genomic instability in the form of high levels of chromosomal aberrations and micronuclei. Cells expressing G83D also grow in an anchorage independent manner, suggesting that the genomic instability results in a carcinogenic phenotype. Our results are consistent with the idea that an inability to remove oxidative damage in an efficient manner at the replication fork leads to genomic instability and mutagenesis. We suggest that individuals who harbor the G83D NEIL1 variant face an increased risk for human cancer.

<p>Berzosertib (VE-822) inhibits gastric cancer cell proliferation via base excision repair system</p>

“…The higher expression of the NEIL1 mRNA level is significantly associated with worse OS in all GC cancer patients. The NEIL1 DNA glycosylase can recognize oxidized bases and remove damage before the formation of the replication fork 40. Nevertheless, Shinmura suggested that among breast invasive carcinoma, a decline of NEIL1 expression predicted a poor survival outcome, but gastric cancer was not included 41…”

Characterization of rare NEIL1 variants found in East Asian populations

“…1) were glycosylase inactive (13), and suggested that catalytically or otherwise compromised NEIL1 variants could add to overall DNA adduct burdens sustained by hepatocytes. Relevant to this conclusion, recent data demonstrated that expression of the G83D variant of NEIL1 resulted in an oncogenic phenotype in MCF10A immortal human breast epithelial cells (14). Expression of this variant, in the presence of WT NEIL1, induced replication stress, genomic instability, and cellular transformation through a mechanism postulated to involve the masking of DNA adducts at replication forks that are substrates for NEIL1.…”

Nei Endonuclease VIII-Like1 (NEIL1) Inhibits Apoptosis of Human Colorectal Cancer Cells

“…The NEIL1 gene polymorphism is closely related to tumorigenesis [3]. The G83D mutation of the NEIL1 gene can induce genomic instability and cell transformation [4]. The inactivating mutation of NEIL1 disrupts the DNA repairing system, and the accumulation of bases damaged by oxidative stress would lead to the development of gastric cancer [5].…”