Role of Nrf2 signaling pathway in the radiation tolerance of patients with head and neck squamous cell carcinoma: an in vivo and in vitro study

Abstract

We aimed to investigate the relationship between the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway and the radiation tolerance of patients with head and neck squamous cell carcinoma (HNSCC). From January 2015 to January 2016, 117 patients with HNSCC were enrolled in our study and assigned into the sensitive and tolerance groups based on curative effect. Immunohistochemistry (IHC) was conducted to measure protein expressions of Nrf2, heme oxygenase-1 (HO1), NADPH quinine oxidoreductase 1 (NQO1) and glutathione S-transferase (GST). Human squamous cell carcinoma cell line, HSC-4, was induced by radiation to construct the HSC-4-radiation resistance (RR) cell line. HSC-4 and HSC-4-RR were also assigned into the blank, negative control (NC) and Nrf2 siRNA groups. Cell Counting Kit-8 (CCK-8), quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting were employed to detect cell viability, mRNA expression and protein expression, respectively, of Nrf2, HO1, NQO1 and GST. A total of 40 nude mice were equally assigned into the untreated, Nrf2 siRNA, radiation therapy (RT) and RT + Nrf2 siRNA groups. Compared with the sensitive group, patients in the tolerance group had upregulated Nrf2, HO1, NQO1 and GST expressions. HSC-4-RR cell line had improved cell viability and higher protein and mRNA expressions of Nrf2, HO1, NQO1 and GST compared with HSC-4 cell line. Compared with the HSC-4-NC and HSC-4-blank groups, the HSC-4-Nrf2 siRNA group had downregulated cell viability. Compared with the HSC-4-RR-NC and HSC-4-RR-blank groups, the HSC-4-RR-Nrf2 siRNA group had lower cell viability. However, the HSC-4-RR-Nrf2 siRNA group had elevated cell viability than the HSC-4-Nrf2 siRNA group. Tumor volume and tumor weight in the RT and RT + Nrf2 siRNA groups decreased evidently. The RT + Nrf2 siRNA group exhibited decreased tumor volume and tumor weight in comparison with the RT group. Our data demonstrated that downregulation of HO1, NQO1 and GST via inhibiting Nrf2 signaling pathway reduces the radiation tolerance of patients with HNSCC.

Reprogramming of Energy Metabolism in Response to Radiotherapy in Head and Neck Squamous Cell Carcinoma

“…It has been demonstrated that in HPV-negative HNSCC cells, activation of Nrf2 is also associated with resistance to treatment [66] and conversely, its deactivation induces radiosensitivity. This Nrf2 activation in HNSCC is also associated to the upregulation of HO-1, NQO1 and GST, which are effective antioxidants (Figure 1) [67].…”

Impact and Relevance of the Unfolded Protein Response in HNSCC

“…Similarly, inhibition of NRF2 by siRNA in the radiation resistant HSC-4 cell line led to decreased cell viability compared to their control counterparts. Subcutaneous injection of HSC-4 cells showed that tumor size, volume and weight were significantly reduced upon radiotherapy and more obvious when NRF2 was silenced [84].…”

Tumor genotype dictates radiosensitization afterAtmdeletion in brainstem gliomas

“…Dysregulation of the NRF2 pathway is an established mechanism of radiation resistance of human tumors and mouse models of cancer (28,29). NRF2 acts as a master transcriptional regulator of the cellular response to oxidative stress and alters the response to radiation by reducing intracellular reactive oxygen species (ROS) and DNA damage (28,30).…”