Ionizing irradiation induces apoptotic damage of salivary gland acinar cells via NADPH oxidase 1-dependent superoxide generation

https://doi.org/10.1016/j.bbrc.2007.11.039Get rights and content

Abstract

Reactive oxygen species (ROS) have important roles in various physiological processes. Recently, several novel homologues of the phagocytic NADPH oxidase have been discovered and this protein family is now designated as the Nox family. We investigated the involvement of Nox family proteins in ionizing irradiation-induced ROS generation and impairment in immortalized salivary gland acinar cells (NS-SV-AC), which are radiosensitive, and immortalized ductal cells (NS-SV-DC), which are radioresistant. Nox1-mRNA was upregulated by γ-ray irradiation in NS-SV-AC, and the ROS level in NS-SV-AC was increased to approximately threefold of the control level after 10 Gy irradiation. The increase of ROS level in NS-SV-AC was suppressed by Nox1-siRNA-transfection. In parallel with the suppression of ROS generation and Nox1-mRNA expression by Nox1-siRNA, ionizing irradiation-induced apoptosis was strongly decreased in Nox1-siRNA-transfected NS-SV-AC. There were no large differences in total SOD or catalase activities between NS-SV-AC and NS-SV-DC although the post-irradiation ROS level in NS-SV-AC was higher than that in NS-SV-DC. In conclusion, these results indicate that Nox1 plays a crucial role in irradiation-induced ROS generation and ROS-associated impairment of salivary gland cells and that Nox1 gene may be targeted for preservation of the salivary gland function from radiation-induced impairment.

Section snippets

Materials and methods

Cell lines. Immortalized normal salivary gland (NS-SV-AC and NS-SV-DC) cell lines were provided by Dr. M. Azuma (Second Department of Oral and Maxillofacial Surgery, School of Dentistry, Tokushima University) and were maintained in keratinocyte basal medium-2 (KBM-2, Cambrex Bio Science Inc., Walkersville, MD) [12].

MTT assay. The antiproliferative effects of radiation were determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) dye uptake method [13].

Reverse

The sensitivity of NS-SV-AC and NS-SV-DC cells to γ-rays

When NS-SV-AC cells were exposed to a single dose irradiation of 2–10 Gy, their growth was inhibited in a dose-dependent manner and the growth inhibition was approximately 50% of the control level after 10 Gy irradiation. In NS-SV-DC cells, the growth inhibition was approximately 15% after 2–10 Gy irradiation, indicating that NS-SV-DC cells were rather nonsensitive to γ-rays compared with NS-SV-AC cells (Fig. 1A). Apoptosis in the irradiated NS-SV-AC cells was increased in a time-dependent manner

Discussion

Along with studies on ROS generation, increasing studies of the role of Nox family proteins have been reported. However, the involvement of ROS and Nox family proteins in the impairment of the salivary glands has not been sufficiently clarified. There are several causes of salivary gland dysfunction, including aging, medications, radiotherapy for cancers of the head and neck, and serious salivary gland disorders. The iatrogenic (cancer treatment-induced) hypofunction of the salivary glands has

References (26)

  • H. Sumimoto et al.

    Molecular composition and regulation of the Nox family NAD(P)H oxidases

    Biochem. Biophys. Res. Commun.

    (2005)
  • E. Salvolini et al.

    Age-related modifications in human unstimulated whole saliva: a biochemical study

    Aging (Milano)

    (2000)
  • R.M. Nagler et al.

    Salivary gland involvement in rheumatoid arthritis and its relationship to induced oxidative stress

    Rheumatology (Oxford)

    (2003)
  • Cited by (62)

    • Targeting of cellular redox metabolism for mitigation of radiation injury

      2020, Life Sciences
      Citation Excerpt :

      The production of superoxide by NOX1 has also been shown to potentiate apoptosis induction in salivary gland acinar cells. Selective inhibition of NOX1 in the salivary gland acinar cells (NS-SV-AC) showed reduction of apoptosis, which is mediated by ROS derived NOX1 enzyme [64]. Upregulation of NOX2 and NOX4 may be involved in radiation-induced bystander and non-targeted effect, a phenomenon that causes ROS generation in neighboring non-irradiated cells or distant organs [17].

    • In vivo assessment of reactive oxygen species production and oxidative stress effects induced by chronic exposure to gamma radiation in Caenorhabditis elegans

      2020, Free Radical Biology and Medicine
      Citation Excerpt :

      These radicals are continuously produced in the cells of organisms during exposure to ionizing radiation, and increased ROS levels have been measured in a wide range of species, including the green algae Chlamydomonas reinhardtii, the aquatic macrophyte Lemna minor and zebrafish [30,40,81]. Despite a short (nanoseconds) half-life [7], the formation of ionizing radiation-induced radicals has shown to increase persistently in the cells during prolonged exposures [15,74]. This may result in changes of the cellular redox balance, which can lead to the perturbation of essential biochemical processes including metabolism [26].

    • Atorvastatin increases oxidative stress and inhibits cell migration of oral squamous cell carcinoma in vitro

      2019, Oral Oncology
      Citation Excerpt :

      In breast cancer cells, paclitaxel promotes ROS formation through the translocation of Rac1, which positively regulates the activity of NADPH oxidase. Currently, radiotherapy is widely used in several cancer treatments, mainly depending on ROS generation [52–55]. Therefore, the use of atorvastatin in the treatment of oral cancer could be an option to avoid the high recurrence rate after the treatments currently used.In summary, the present study showed that atorvastatin increases the oxidative stress and angiogenesis in oral squamous cell carcinomas.

    View all citing articles on Scopus
    View full text