Tempol Protects Against Radiation Injury in the Submandibular Gland Through the β-Catenin Signaling Pathway.

BACKGROUND

Radiation damage severely impacts salivary gland function and cell survival, especially in head and neck radiotherapy. Tempol (TPL), a free radical scavenger, has shown protective effects against radiation damage. This research aimed to investigate the protective effects of TPL on radiation-induced damage in Hs917.T cells and the submandibular gland (SMG) of C57BL/6 mice, along with the mechanisms involved.

METHODS

Human parotid fibroblasts (Hs917.T) were pre-treated with TPL and exposed to ionizing radiation (IR). Protective effects were evaluated using MTT, clonogenic survival assays, flow cytometry, and intracellular reactive oxygen species levels. In vivo, C57BL/6 mice were pre-treated with TPL (275 mg/kg) and exposed to 15 gray (Gy). Effects were assessed by survival rates, body weight changes, histological analysis, and TUNEL staining. Changes in apoptosis-related markers and β-catenin signaling pathway were analyzed, and the role of TPL was verified using the β-catenin inhibitor XAV939.

RESULTS

TPL pre-treatment increased cell survival, reduced apoptosis, alleviated cell cycle arrest, and decreased intracellular superoxide and hydrogen peroxide levels in Hs917. T cells. In C57BL/6 mice, pre-treatment with TPL improved survival, mitigated weight loss, reduced SMG damage, and decreased apoptosis. TPL inhibited IR-induced apoptosis by increasing Bcl-2 expression and decreasing Bax and caspase-9 levels. TPL exerted anti-apoptotic and protective effects by upregulating the expression of β-catenin, promoting its nuclear translocation, and inhibiting its phosphorylation. These protective effects of TPL were reversed by XAV939.

CONCLUSIONS

TPL exerted protective effects against IR-induced damage in Hs917.T cells and the SMG of C57BL/6 mice through activating the β-catenin signaling pathway, inhibiting cell apoptosis, and alleviating oxidative stress.