Targeting of β1 integrins impairs DNA repair for radiosensitization of head and neck cancer cells

Oncogene. 2016 Mar 17;35(11):1353-62. doi: 10.1038/onc.2015.212. Epub 2015 Jun 15.

Abstract

β1 Integrin-mediated cell-extracellular matrix interactions allow cancer cell survival and confer therapy resistance. It was shown that inhibition of β1 integrins sensitizes cells to radiotherapy. Here, we examined the impact of β1 integrin targeting on the repair of radiation-induced DNA double-strand breaks (DSBs). β1 Integrin inhibition was accomplished using the monoclonal antibody AIIB2 and experiments were performed in three-dimensional cell cultures and tumor xenografts of human head and neck squamous cell carcinoma (HNSCC) cell lines. AIIB2, X-ray irradiation, small interfering RNA-mediated knockdown and Olaparib treatment were performed and residual DSB number, protein and gene expression, non-homologous end joining (NHEJ) activity as well as clonogenic survival were determined. β1 Integrin targeting impaired repair of radiogenic DSB (γH2AX/53BP1, pDNA-PKcs T2609 foci) in vitro and in vivo and reduced the protein expression of Ku70, Rad50 and Nbs1. Further, we identified Ku70, Ku80 and DNA-PKcs but not poly(ADP-ribose) polymerase (PARP)-1 to reside in the β1 integrin pathway. Intriguingly, combined inhibition of β1 integrin and PARP using Olaparib was significantly more effective than either treatment alone in non-irradiated and irradiated HNSCC cells. Here, we support β1 integrins as potential cancer targets and highlight a regulatory role for β1 integrins in the repair of radiogenic DNA damage via classical NHEJ. Further, the data suggest combined targeting of β1 integrin and PARP as promising approach for radiosensitization of HNSCC.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acid Anhydride Hydrolases
  • Animals
  • Antibodies, Monoclonal / immunology
  • Antigens, Nuclear / biosynthesis
  • Antineoplastic Agents / pharmacology
  • Carcinoma, Squamous Cell / genetics*
  • Carcinoma, Squamous Cell / radiotherapy
  • Cell Cycle Proteins / biosynthesis
  • Cell Line, Tumor
  • DNA Breaks, Double-Stranded / radiation effects*
  • DNA End-Joining Repair / drug effects
  • DNA End-Joining Repair / genetics*
  • DNA End-Joining Repair / radiation effects
  • DNA Repair Enzymes / biosynthesis
  • DNA-Binding Proteins / biosynthesis
  • Extracellular Matrix / metabolism
  • Female
  • Head and Neck Neoplasms / genetics*
  • Head and Neck Neoplasms / radiotherapy
  • Humans
  • Integrin beta1 / genetics*
  • Integrin beta1 / immunology
  • Ku Autoantigen
  • Male
  • Mice
  • Mice, Nude
  • Nuclear Proteins / biosynthesis
  • Phthalazines / pharmacology
  • Piperazines / pharmacology
  • Poly(ADP-ribose) Polymerases / metabolism
  • RNA Interference
  • RNA, Small Interfering / genetics
  • Radiation-Sensitizing Agents / metabolism*
  • Squamous Cell Carcinoma of Head and Neck

Substances

  • Antibodies, Monoclonal
  • Antigens, Nuclear
  • Antineoplastic Agents
  • Cell Cycle Proteins
  • DNA-Binding Proteins
  • Integrin beta1
  • NBN protein, human
  • Nuclear Proteins
  • Phthalazines
  • Piperazines
  • RNA, Small Interfering
  • Radiation-Sensitizing Agents
  • Poly(ADP-ribose) Polymerases
  • Acid Anhydride Hydrolases
  • Rad50 protein, human
  • Xrcc6 protein, human
  • Xrcc6 protein, mouse
  • Ku Autoantigen
  • DNA Repair Enzymes
  • olaparib