The Antiviral Agent Cidofovir Induces DNA Damage and Mitotic Catastrophe in HPV-Positive and -Negative Head and Neck Squamous Cell Carcinomas In Vitro.

Femke Verhees,Wisse Evert Haakma,Ernst Jan Speel,Robin Jacobs,Mat Rousch,Dion Legemaate,Imke Demers,Bernd Kremer

doi:10.3390/cancers11070919

Abstract

Cidofovir (CDV) is an antiviral agent with antiproliferative properties. The aim of our study was to investigate the efficacy of CDV in HPV-positive and -negative head and neck squamous cell carcinoma (HNSCC) cell lines and whether it is caused by a difference in response to DNA damage. Upon CDV treatment of HNSCC and normal oral keratinocyte cell lines, we carried out MTT analysis (cell viability), flow cytometry (cell cycle analysis), (immuno) fluorescence and western blotting (DNA double strand breaks, DNA damage response, apoptosis and mitotic catastrophe). The growth of the cell lines was inhibited by CDV treatment and resulted in γ-H2AX accumulation and upregulation of DNA repair proteins. CDV did not activate apoptosis but induced S- and G2/M phase arrest. Phospho-Aurora Kinase immunostaining showed a decrease in the amount of mitoses but an increase in aberrant mitoses suggesting mitotic catastrophe. In conclusion, CDV inhibits cell growth in HPV-positive and -negative HNSCC cell lines and was more profound in the HPV-positive cell lines. CDV treated cells show accumulation of DNA DSBs and DNA damage response activation, but apoptosis does not seem to occur. Rather our data indicate the occurrence of mitotic catastrophe.

Highlights

Each year ~600,000 people worldwide are diagnosed with head and neck squamous cell carcinoma (HNSCC), making HNSCC the sixth most common cancer in the world [1]
Rather our data indicate the occurrence of mitotic catastrophe
The occurrence of DNA damage induction in the cell lines was confirmed by irradiation of 93-VU-147T, as there was an increase of γ-H2AX in the irradiated cells compared to the non-irradiated cells after both 4 and 24 h (Figure S1)

Summary

Introduction

Each year ~600,000 people worldwide are diagnosed with head and neck squamous cell carcinoma (HNSCC), making HNSCC the sixth most common cancer in the world [1]. HPV-positive HNSCC is considered to be a distinct clinical and molecular entity in comparison to HPV-negative HNSCC [2]. The mortality rates have hardly decreased over the last decades and the five-year survival rate still ranges between 40–50%, even though improvements in detection and treatment have been achieved [3]. The HPV status of the tumor possesses powerful prognostic value, where HPV-positive patients have a more favorable prognosis [4,5]. There is an urgent need for new agents that can be integrated into or replace current treatment regimens to improve outcome and quality of life of HNSCC patients

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Results

Conclusion