# Rongbei Maimendong Decoction Promotes Radiosensitivity of Non‐Small Cell Lung Cancer Cells by Inhibiting SOD1 Expression

## TL;DR

This study shows that Rongbei Maimendong Decoction improves the effectiveness of radiation therapy for non-small cell lung cancer by inhibiting SOD1, a protein involved in DNA repair.

## Contribution

The study identifies β-thymidine in RBMD as a novel compound that enhances radiosensitivity by inhibiting SOD1 expression in NSCLC cells.

## Key findings

- RBMD inhibited tumor growth in mice in a dose-dependent manner when combined with radiotherapy.
- β-thymidine reduced SOD1 levels, suppressed NSCLC cell proliferation and migration, and increased apoptosis.
- β-thymidine attenuated SOD1's protective effect against DNA damage, enhancing radiosensitivity in NSCLC cells.

## Abstract

Some natural remedies in traditional Chinese medicine (TCM) inhibit tumor progression and increase sensitivity in the treatment of patients who have received radiation therapy. However, the specific synergistic effect of the active ingredients in the traditional Chinese therapeutic Rongbei Maimendong decoction (RBMD) on sensitivity to radiation therapy for non‐cell lung cancer (NSCLC) is still unclear. RBMD inhibited transplanted tumor cell growth in mice, showing a dose‐dependent effect in tumor growth inhibition following radiotherapy. Our study utilized bioinformatics analysis and liquid chromatography with tandem mass spectrometry to identify the presence of β‐thymidine (β‐thy) in Phellodendron bark, the primary component of RBMD. This compound modulated mRNA and protein levels of SOD1 by interacting with SOD1, inhibiting the malignant characteristics (proliferation, apoptosis, migration, and invasion) of NSCLC cells. Furthermore, apoptosis assays demonstrated that β‐thy attenuated tumor growth in mice following radiotherapy. Single‐cell gel electrophoresis assays demonstrated the ability of SOD1 to mitigate DNA damage in irradiated (IR) NSCLC cells, suppressing apoptosis, and that β‐thy attenuated this SOD1 protective effect, mitigating NSCLC cells resistance to radiation. We propose that the consumption of RBMD, which is rich in β‐thy, may enhance NSCLC radiosensitivity by hindering DNA repair mechanisms and facilitating apoptosis through DNA damage augmentation.