Sibylla Kohl , Florentine S.B. Subtil , Vanessa Climenti , Houmam Anees , Ann C. Parplys , Rita Engenhart-Cabillic , Sebastian Adeberg , Ekkehard Dikomey , Ulrike Theiß
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引用次数: 0
Abstract
Objectives
Human papilloma virus (HPV)-positive head and neck squamous cell carcinoma (HNSCC) cells are highly radiosensitive resulting from an elevated number of DNA double-strand breaks (DSB) remaining after irradiation. Partially this effect is due to a defective homologous recombination (HR). HPV-positive cells also show pronounced instability of chromosome 3, which codes for the kinase ataxia-telangiectasia and Rad3-related (ATR) protein, a central player of HR. If there is a contribution of ATR to the radiosensitivity of HPV-positive cells remains unclear, and this in-vitro study tested a functional involvement of ATR expression.
Methods
The study was performed with six HPV-negative and six HPV-positive HNSCC cell lines. Gene copy number and gene expression were determined via qRT-PCR, protein expression by Western Blot. Response of cells towards irradiation in dependence of ATR expression was tested after siRNA Knock-down (ATRKD). Clonogenic survival after photon irradiation was evaluated by colony formation assay and DSBs were visualized by γH2AX/53BP1 co-staining.
Results
ATR gene copy number and expression were not altered. Protein level was almost two-fold lower in HPV-positive compared to HPV-negative cells, but fully functional as observed by active phosphorylation in response towards irradiation. ATRKD resulted in a further increase in both, radiosensitivity as well as number of residual DSBs, but only for HPV-positive cells.
Conclusion
Since the effect of ATRKD was compensated in HPV-negative but not in HPV-positive cells, these data revealed that the two-fold lower level of ATR in HPV-positive cells does not account for their enhanced inherent radiosensitivity, but acts additive to irradiation.
期刊介绍:
Translational Oncology publishes the results of novel research investigations which bridge the laboratory and clinical settings including risk assessment, cellular and molecular characterization, prevention, detection, diagnosis and treatment of human cancers with the overall goal of improving the clinical care of oncology patients. Translational Oncology will publish laboratory studies of novel therapeutic interventions as well as clinical trials which evaluate new treatment paradigms for cancer. Peer reviewed manuscript types include Original Reports, Reviews and Editorials.