EACR26-0488

Sphingosine-1-phosphate receptor 3 confers tumor metastasis in lung cancer resistant to third-generation EGFR inhibitor

M. Lai¹, J. Chen¹, Y. Qin¹, H. Zhang², J. Ding¹, H. Xie^1,3

¹Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
²Shanghai Lung Cancer Center, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
³Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Zhongshan, China

Introduction:

The third-generation EGFR tyrosine kinase inhibitors (TKIs) have significantly improved the survival of lung cancer patients harboring EGFR mutations. Limertinib (ASK120067), an independently developed third-generation EGFR inhibitor from our team, was launched in China in 2025. As reported for the FDA approved osimertinib (AZD9291), clinical responses to third-generation EGFR TKIs are not durable. Clinical observations indicate that metastatic relapses constitute a major cause of treatment failure in the third-generation EGFR TKI-treated lung cancer patients. Studies on the mechanisms associated with metastatic relapse in lung cancer patients after EGFR TKIs resistance are far from fully understood.

Material and method:

RNA-seq analysis was employed to identify the differentially expressed genes between parental and EGFR TKI-resistant models. The expression of sphingosine-1-phosphate receptor 3 (S1PR3) was confirmed by immunoblotting, RT-PCR and immunohistochemistry. Trans-well assay, chromatin immunoprecipitation assay, promoter luciferase reporter assay and in vivo luciferase imaging assay were employed to explore the mechanisms that mediated metastasis in EGFR TKI-resistant tumors.

Result and discussion:

Using transcriptomics analyses on established ASK120067-resistant and AZD9291-resistant tumor models, we identified an aberrant upregulation of S1PR3 in resistant cells, which conferred enhanced metastatic potential to lung cancer. Genetic and pharmacological inhibition of S1PR3 dramatically reduced the metastasis of resistant cells, while overexpression of S1PR3 potentiated the metastatic abilities of parental cells. Notably, S1PR3 was highly enriched in clinical samples with AZD9291 resistance, and database analysis revealed a significant correlation between elevated S1PR3 expression and poor clinical outcomes. Mechanistic studies revealed that S1PR3 upregulated RAC1-GTP expression, which subsequently activated PAK1 and promoted epithelial-mesenchymal transition (EMT). Moreover, in vivo studies further confirmed that pharmacological inhibition of S1PR3 significantly reduced the metastatic progression of EGFR inhibitor-resistant lung cancer.

Conclusion:

Our findings identify S1PR3 as a critical driver of metastatic progression in third-generation EGFR inhibitor-resistant lung cancer, highlighting targeting S1PR3 as a potential therapeutic strategy that could be employed to prevent tumor progression.

Acknowledgement:

This work was supported by grants from the Special Funds of the National Natural Science Foundation of China (82441046) and the National Natural Science Foundation of China (82273948).