Molecular dynamics study on conformational differences between dGMP and 8-oxo-dGMP: Effects of metal ions

NUDT expression is predictive of prognosis in patients with clear cell renal cell carcinoma

The nudix hydroxylase (NUDT) family of genes may have notable roles in cancer growth and metastasis. The present study aimed to determine the prognostic ability of NUDT genes in clear cell renal cell carcinoma (ccRCC). Data from 509 patients with ccRCC was obtained from The Cancer Genome Atlas (TCGA) database and 192 patient samples from Fudan University Shanghai Cancer Center (FUSCC) were analyzed in the present study. The expression profile of NUDT gene family members in the TCGA cohort was obtained from the TCGA RNA sequencing database. Pathological characteristics, including age, sex, tumor size, tumor grade, stage, laterality and overall survival were collected. Cox proportional hazards regression model and Kaplan-Meier survival analysis were performed to assess the associations between pathological characteristics and expression levels of NUDT family genes. NUDT family genes that exhibited associations with overall survival (OS) were further validated in the FUSCC cohort. In the TCGA cohort, Cox proportional hazards analysis found that NUDT5 [hazards ratio (HR)=1.676; 95% confidence interval (CI), 1.097-2.559] and NUDT17 (HR=1.375; 95% CI, 1.092-1.732) were predictive of ccRCC prognosis. Further analysis revealed that low NUDT5 (P<0.0001) and NUDT17 (P<0.0001) expression were associated with poorer OS rates in the TCGA cohort. In the FUSCC cohort, low NUDT5 expression was also associated with poor OS rates (P=0.0116), and tumor grade was a factor that influenced the expression level of NUDT5 (P=0.016).

The use of modified and non-natural nucleotides provide unique insights into pro-mutagenic replication catalyzed by polymerase eta

This report evaluates the pro-mutagenic behavior of 8-oxo-guanine (8-oxo-G) by quantifying the ability of high-fidelity and specialized DNA polymerases to incorporate natural and modified nucleotides opposite this lesion. Although high-fidelity DNA polymerases such as pol δ and the bacteriophage T4 DNA polymerase replicating 8-oxo-G in an error-prone manner, they display remarkably low efficiencies for TLS compared to normal DNA synthesis. In contrast, pol η shows a combination of high efficiency and low fidelity when replicating 8-oxo-G. These combined properties are consistent with a pro-mutagenic role for pol η when replicating this DNA lesion. Studies using modified nucleotide analogs show that pol η relies heavily on hydrogen-bonding interactions during translesion DNA synthesis. However, nucleobase modifications such as alkylation to the N2 position of guanine significantly increase error-prone synthesis catalyzed by pol η when replicating 8-oxo-G. Molecular modeling studies demonstrate the existence of a hydrophobic pocket in pol η that participates in the increased utilization of certain hydrophobic nucleotides. A model is proposed for enhanced pro-mutagenic replication catalyzed by pol η that couples efficient incorporation of damaged nucleotides opposite oxidized DNA lesions created by reactive oxygen species. The biological implications of this model toward increasing mutagenic events in lung cancer are discussed.