Synergistic Effects of Melatonin on Radiosensitization in Carbon-ion Radiotherapy

Area of Science:

• Oncology
• Radiation Biology
• Molecular Medicine

Background:

• Melatonin's synergy with photon irradiation is known, but its role in carbon-ion radiotherapy is unclear.
• Understanding melatonin's impact on carbon-ion radiotherapy is crucial for optimizing cancer treatment.

Purpose of the Study:

• To investigate the mechanisms and clinical benefits of combining melatonin with carbon-ion radiotherapy.
• To elucidate how melatonin affects cell-cycle modulation and DNA repair in the context of carbon-ion treatment.

Main Methods:

• Utilized melanoma (B16F10) and osteosarcoma (LM8) cell lines.
• Assessed cell-cycle, DNA repair, and gene expression (RNA sequencing) after melatonin and irradiation.
• Validated findings on LM8 cells.

Main Results:

• Melatonin pre-treatment reduced cancer cell survival after photon and carbon-ion radiation.
• Melatonin inhibited G2/M arrest and DNA double-strand break repair gene expression.
• Observed favorable gene expression changes related to survival and metastasis; LM8 cells showed increased radiosensitivity.

Conclusions:

• Exogenous melatonin enhances carbon-ion radiotherapy's cytotoxicity in vitro.
• Melatonin suppresses DNA double-strand break repair pathways, increasing tumor cell radiosensitivity.