Although targeted therapy and immunotherapy have provided new options for nasopharyngeal carcinoma, radioresistance and distant metastasis are still the main causes of treatment failure. Our recent study has indicated potential antitumor effects of the Semen podocarpi extract (SPE). This study aimed to explore the radiosensitizing effect on radioresistant nasopharyngeal carcinoma (CNE-2R) cells.
Chemical components in SPE were identified by UPLC-MS/MS. CCK-8 and cell cloning experiments were applied to evaluate the effects of SPE on the proliferation of CNE-2R cells, and a single-hit multitarget model was used to calculate the radiobiological parameters. Cell apoptosis and cell cycle were analyzed by flow cytometry, and the levels of genes and proteins of the Raf/MEK/ERK pathway were determined by RT-PCR and Western blotting.
A total of 37 compounds from SPE were identified, and SPE with or without irradiation inhibited the proliferation of CNE- 2R cells. SPE also promoted apoptosis, arrested cells in the G₂/M phase, and presented radiosensitizing effects. Compared with irradiation alone, the effects of SPE+irradiation on apoptosis and cell cycle distribution were not significantly different. In addition, SPE had no significant effect on MEK gene expression. SPE significantly increased the gene expression of C-Raf and significantly reduced the protein expression of C-Raf, as well as the gene and protein expression of ERK1 and ERK2. The protein levels of C-Raf, ERK1, and ERK2 were also significantly lower in cells treated with SPE+irradiation than in cells treated with irradiation alone.
SPE could inhibit cell proliferation and promote apoptosis via cell cycle arrest and Raf/MEK/ERK pathway regulation.

The work entitled “Semen podocarpi extract enhances radiosensitivity in nasopharyngeal carcinoma cells via Raf/MEK/ERK signaling pathway” was published on Asian Pacific Journal of Tropical Biomedicine (published on Jan. 17, 2025).
DOI: 10.4103/apjtb.apjtb_556_24