Sanyang Xuedai enhances radiosensitivity in human non-small cell lung cancer cells through the activation of TLR2 to increase iNOS/NO production-mediated autophagy.

Abstract

Radiotherapy (RT) is a key treatment for non-small cell lung cancer (NSCLC) patients who are ineligible for surgery. Sanyang Xuedai (SYKT), a traditional Chinese herbal formula, has previously been shown to enhance the effectiveness of RT in advanced NSCLC tumors. This study aimed to investigate the effects of SYKT combined with RT on RT-resistant NSCLC and to elucidate the underlying mechanisms involved. RT-resistant NCI-H460R cells were established by continuous exposure to ionizing radiation (IR). A xenograft model was generated by injecting NCI-H460R cells into the left back of nude mice. Gene and protein expression levels of key factors were assessed using RT‒qPCR, western blotting, immunofluorescence, and immunohistochemistry. Cell proliferation and apoptosis were evaluated through a CCK-8 assay, EdU staining, and flow cytometry. The results show that the combined intervention of SYKT and IR inhibited the proliferation of NCI-H460R cells and suppressed tumor growth in nude mice (one-way ANOVA with Tukey's post-hoc test, P < 0.05). Moreover, SYKT combined with IR increased the proportion of cells in the G2/M phase, reduced the proportion of cells in the G0/G1 phase, and promoted apoptosis (one-way ANOVA with Tukey's post-hoc test, P < 0.05). In addition, the combination therapy also upregulated the expression of the autophagy-related proteins LC3 II/I and Beclin 1 and the cell cycle proteins Cyclin B1 and CDC2, as well as iNOS, while inhibiting p62 expression and promoting NO production (one-way ANOVA with Tukey's post-hoc test, P < 0.05). Mechanistically, SYKT enhances NO synthesis by activating the TLR2/iNOS signaling axis, which in turn induces autophagy and increases the sensitivity of NSCLC to radiotherapy. This study demonstrated that SYKT can increase the radiosensitivity of NSCLC by activating TLR2 to increase iNOS/NO production, thereby mediating autophagy. Clinically, combining SYKT with radiotherapy may provide a promising and well-tolerated strategy to overcome acquired radioresistance and improve the efficacy of radiotherapy in patients with inoperable or radioresistant NSCLC.

Supplementary information: The online version contains supplementary material available at 10.1007/s10616-026-01027-2.