Molecular disruption of NBS1 with targeted gene delivery enhances chemosensitisation in head and neck cancer

Abstract

Background:A fibroblast growth factor 2 (FGF2)-targeted adenoviral system can alter viral tropism and allow for improved transduction and reduced systemic toxicity. This study is to investigate if the FGF2-targeted adenoviral mutant Nijmegen breakage syndrome 1 (FGF2-Ad-NBS1) gene transfer can enhance cisplatin chemosensitisation not only by targeting DNA repair, but also through the induction of antiangiogenesis, whereas at the same time reducing toxicities in treating head and neck squamous cell carcinoma (HNSCC).Methods:The human HNSCC cell line was treated in vitro and in a nude mouse xenograft model. We conducted verification of binding ability of mutant NBS1 and downregulation of MRN complex, evaluation of transduction efficiency and combined antitumour activities. The antiangiogenesis mechanism was also investigated. Finally, we estimated the distribution of adenoviral vector in the liver.Results:The mutant NBS1 protein retains the binding ability and effectively suppresses the expression level of the MRN in infected cells. Transduction efficiency in vitro and cisplatin chemosensitisation were upregulated. The FGF2-Ad-NBS1 also showed detargeting the viral vectors away from the liver. The downregulation of NF-κB expression was supposed to correlate with increased antiangiogenesis.Conclusions:FGF2-targeted adenoviral system enhances the cisplatin chemosensitisation of mutant NBS1 and may avoid viral-associated liver toxicities.

Genetic Variants of NBS1 Predict Clinical Outcome of Platinum-based Chemotherapy in Advanced Non-small Cell Lung Cancer in Chinese

“…Among those, the NBS1 protein is the key regulator of the MRN complex, which recruits MRE11/RAD50 or retains them at the vicinity of DNA damage sites by direct binding to histone H2AX. Mutations in NBS1 significantly downregulate MRN complex expression and markedly disrupt its function, thus enhancing cisplatin-induced DNA damage and cytotoxicity (Tran et al, 2004;Araki et al, 2010). Studies in mice have indicated that heterozygous for NBS1-null mutations develop tumors in lung, liver, mammary gland and prostate (Dumon-Jones et al, 2003;Zhang et al, 2006).…”

Dual Disruption of DNA Repair and Telomere Maintenance for the Treatment of Head and Neck Cancer

“…We have previously demonstrated that HNSCC cell lines treated with a dominant-negative adenoviral construct expressing a truncated (C-terminal only) Nbs1 protein, mutant Nbs1 (Ad-Nbs1), results in downregulation of all three components of the MRN complex (18). As shown in Fig.…”

“…A single i.t. injection of virus (50 ml, 2 Â 10 10 PFU/mL) or equal volume of saline was performed using a Hamilton syringe as previously described (15,18). The PARPi was administered orally as a single dose on the same day after the mice recovered from anesthesia.…”

“…We have previously investigated multiple therapeutic targets focused on DNA repair pathways, including the sensitization of cancer cells to chemotherapy and radiotherapy through the molecular disruption of the Mre11, Rad50, and Nbs1 (MRN) complex (15)(16)(17)(18)(19), as well as through poly (ADP-ribose) polymerase (PARP) inhibition (20). The MRN complex, which plays a critical role in the repair of DNA double-strand breaks (DSB), has been recently implicated in telomere maintenance through interaction with the shelterin complex in both hTERT-positive and ALT cancer cells (21)(22)(23)(24).…”

DNA Repair Endonucleases: Physiological Roles and Potential as Drug Targets

“…122,123 In addition to gene therapy-targeted disruption of the MRN complex, a forward chemical genetic screen of small molecules has also identified the MRN inhibitor "Mirin." 124 Mirin was shown to disrupt the association of MRN with ATM and also the nuclease activity of MRN blocking efficient HR.…”