Association of hOGG1-Cys variants with occurrence of p53 and EGFR deletion mutations in non-small cell lung cancer

Abstract

Background: The human 8-oxoguanine DNA glycosylase 1 (hOGG1) gene encodes a DNA glycosylase that removes 8-hydroxy-2-deoxyguanine (8-OH-dG) DNA damage to protect against gene mutations. The association of hOGG1 Ser326Cys polymorphism with lung cancer risk has predicted that hOGG1-Cys variants are less effective at removing 8-OH-dG damage from DNA; therefore, these variants might show an increased occurrence of tumor suppressor gene and oncogene mutations. However, no evidence has yet supported this hypothesis.

Methods: Direct sequencing was performed to examine the mutations of p53 and EGFR genes in lung tumors from patients with non-small cell lung cancer (NSCLC). Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to examine hOGG1 Ser326Cys polymorphism in this study population.

Results: A total of 99 p53-mutated and 99 EGFR-mutated patients with NSCLC were selected to explore the possible associations of these mutations with hOGG1 Ser326Cys polymorphism. The p53-mutated and EGFR-mutated patients were divided into nondeletion and deletion subgroups. P53 deletion mutations were more commonly observed in male than in female patients (P = 0.030). However, EGFR exon 19 deletion mutations were more prevalent in female and adenocarcinoma patients than in male and squamous cell carcinoma patients (P = 0.028 for genders, P = 0.017 for tumor histology). Interestingly, p53 and EGFR exon 19 deletion mutations were more frequent in patients with hOGG1 Ser/Cys + Cys/Cys hOGG1-Cys variants than with the hOGG1 Ser/Ser genotype (P = 0.010 for p53, P = 0.032 for EGFR).

Conclusions: We suggest that the association of hOGG1 Ser326Cys polymorphism with lung cancer risk could be partially explained by increases in p53 and EGFR deletion mutations.

Key points: SIGNIFICANT FINDINGS OF THE STUDY: NSCLC patients with hOGG1-Cys variants may have a higher risk of p53 and EGFR deletion mutations than with hOGG1 Ser/Ser genotype.

What this study adds: NSCLC patients with hOGG1-Cys variants might be helpful to predict patients having higher risk of EGFR exon 19 deletion mutations and these patients who were treated with gefitinib or erlotinib could be a higher risk to occur EGFR T790M mutation.

Keywords: Deletion mutation; hOGG1 Ser326Cys polymorphism; non-small cell lung cancer (NSCLC).