Fusobacterium nucleatum Caused DNA Damage and Promoted Cell Proliferation by the Ku70/p53 Pathway in Oral Cancer Cells.

Fengxue Geng,Yaping Pan,Ze Lu,Shuwei Zhang,Yunjia Zhang

doi:10.1089/dna.2019.5064

Abstract

Bacterial infection influences genomic stability and integrity by causing DNA damage, which increases the possibility of tumor initiation and development. We aimed to investigate whether Fusobacterium nucleatum, one of the periodontal pathogens, promoted oral squamous cell carcinoma (OSCC) by causing DNA double-strand break (DSB). Tca8113 tongue squamous cell carcinoma cells were infected with F. nucleatum. The expression of γH2AX was detected by western blots and immunofluorescence. The proliferation and cell cycle alterations were tested by CCK8 and flow cytometry, respectively. The expression levels of Ku70, p53, and p27 were evaluated by quantitative real-time polymerase chain reaction and western blots. A plasmid was used for the overexpression of Ku70 to verify the possible relationship between Ku70 and p53. We confirmed the presence of DSBs in the response to F. nucleatum by detecting the expression of γH2AX. The cell proliferation ability was increased with an accelerated cell cycle while the expression of p27 was decreased. Meanwhile, the expression of Ku70 and wild p53 was downregulated. When Ku70 was overexpressed, the expression of wild p53 in response to F. nucleatum infection was upregulated and cell proliferation was accordingly inhibited. We concluded that F. nucleatum infection promoted the proliferation ability of Tca8113 by causing DNA damage via the Ku70/p53 pathway.

Highlights

Oral squamous cell carcinoma (OSCC) is the most common type of head and neck malignancy with a high prevalence and a poor survival rate
We found that the resulting increased proliferation ability and accelerated cell cycle of OSCC cells in response to DNA damage was dependent on the Ku70/p53 pathway
After the cells were infected with F. nucleatum at an MOI of 500, western blotting was used to detect the expression of gH2AX

Summary

Introduction

Oral squamous cell carcinoma (OSCC) is the most common type of head and neck malignancy with a high prevalence and a poor survival rate. It is widely accepted that inflammatory microenvironment is regarded as an important risk factor of all stages of tumor. One of the important inflammatory factors, are being increasingly accepted as a risk factor for various types of cancer including OSCC (Moergel et al, 2013). Based on a recent report, the oral microbiome in OSCC lesions shifts significantly compared to healthy epithelium. Fusobacterium species are regarded as one of the major components of the oral microbiome in OSCC (Perera et al, 2018). The role of Fusobacterium nucleatum in OSCC is being gradually recognized (Binder Gallimidi et al, 2015; Chang et al, 2018; Hsiao et al, 2018)

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