Tricin selectively combats KRAS-mutant non-small cell lung cancer by inhibiting the PDGF-BB-induced SRC/MAPK/AP-1/PD-L1 signaling pathway and potentiating the antitumor effect of an anti-PD-1 antibody

Jia-Xin Li^1,2Shi-Yu Tan³Li-Qi Li²Yu-Hong Zheng²Lin Zhao²Hui-Rong Zhu⁴Hailang He³Yan-Yu Zhang⁵Run-Ze Li⁶Tian-Yu Bao²Yizhong Zhang⁷Xiao-Man Yang²Zhang Hao²Huihui Chen²Bo-Wen Wu²Xin Lin²Xiaosheng Lin⁸Yin Cheng Lin²Xinbing Sui⁹Ying XIE⁶Xianmei Zhou³Pei-Yu Yan^2*

• ¹Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
• ²Macau University of Science and Technology, Taipa, Macao, Macao, SAR China
• ³Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, Liaoning Province, China
• ⁴Shanghai University of Traditional Chinese Medicine, Shanghai, Shanghai Municipality, China
• ⁵Henan University of Chinese Medicine, Zhengzhou, Henan Province, China
• ⁶Guangdong Provincial Hospital of Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong Province, China
• ⁷UM Zhuhai Research Institute, Zhuhai, Guangdong Province, China
• ⁸Guangzhou University of Chinese Medicine, Guangzhou, Guangdong Province, China
• ⁹Hangzhou Normal University, Hangzhou, Zhejiang Province, China

Background: KRAS is a commonly mutated gene present in approximately 30% of NSCLC patients. Currently, the identification of effective therapies for KRAS-mutant NSCLC is difficult. Our previous study has revealed that tricin had selective effects on KRASG12C-mutant NSCLC cell lines. Thus, our aim in this project was to explore the mechanism by which tricin inhibited the progression of KRAS-mutant NSCLC much more deeply.Methods: First, we detected the acute toxicity of an intraperitoneal injection of tricin in mice. Next, we integrated network pharmacology, molecular docking with transcriptomics analysis and biological methods to probe the underlying mechanisms of tricin. Furthermore, we explored the pharmaceutical effects of combination therapy with tricin and an anti-PD-1 inhibitor. Finally, we detected and analyzed the data from clinical samples to prepare for the clinical translation of tricin.Results: Intraperitoneal injection of tricin resulted in low acute toxicity. In vitro, tricin inhibited the migration, proliferation and colony formation of KRASG12C-mutant NSCLC cells. Mechanistically, tricin inhibited KRASG12C-mutant NSCLC cell growth primarily by suppressing the PDGF-BB-induced SRC/MAPK/AP-1/PD-L1 signaling pathway. SRC was identified as a potentially crucial target. In vivo, combined treatment markedly suppressed the growth of tumors and had nearly no toxicity to the organs of the mice. In terms of immune regulation, tricin increased the numbers of CD8+ T lymphocytes and levels of the functional cytokines TNFα, IFNγ, and Granzyme B. Tricin also increased the numbers of B lymphocytes and disrupted the PD-1/PD-L1 pathway. These results indicated that tricin could compensate for the deficiency of immunotherapy and enhance the antitumor activity of immunotherapy. Moreover, the detection of clinical samples indicated that the rate of SRC positivity was higher in elderly patients with KRAS mutations at the early stage. A positive correlation between the expression of SRC and PD-L1 was observed in tumors.Conclusions: We believe that tricin is a safe and promising agent for the treatment of patients with KRAS-mutated NSCLC. Our study provides an experimental basis for improving the clinical application of traditional Chinese medicine.