CCL2 promotes EGFR-TKIs resistance in non-small cell lung cancer via the AKT-EMT pathway

Abstract

Acquired resistance to EGFR tyrosine kinase inhibitors (EGFR-TKIs) represents a primary cause of treatment failure in non-small cell lung cancer (NSCLC) patients. Chemokine (C-C motif) ligand 2 (CCL2) is recently found to play a pivotal role in determining anti-cancer treatment response. However, the role and mechanism of CCL2 in the development of EGFR-TKIs resistance have not been fully elucidated. In the present study, we focus on the function of CCL2 in the development of acquired resistance to EGFR-TKIs in NSCLC cells. Our results show that CCL2 is aberrantly upregulated in EGFR-TKIs-resistant NSCLC cells and that CCL2 overexpression significantly diminishes sensitivity to EGFR-TKIs. Conversely, CCL2 suppression by CCL2 synthesis inhibitor, bindarit, or CCL2 knockdown can reverse this resistance. CCL2 upregulation can also lead to enhanced migration and increased expressions of epithelial-mesenchymal transition (EMT) markers in EGFR-TKI-resistant NSCLC cells, which could also be rescued by CCL2 knockdown or inhibition. Furthermore, our findings suggest that CCL2-dependent EGFR-TKIs resistance involves the AKT-EMT signaling pathway; inhibition of this pathway effectively attenuates CCL2-induced cell migration and EMT marker expression. In summary, CCL2 promotes the development of acquired EGFR-TKIs resistance and EMT while activating AKT signaling in NSCLC. These insights suggest a promising avenue for the development of CCL2-targeted therapies that prevent EGFR-TKIs resistance in NSCLC.

1. Introduction

Lung cancer remains a primary cause of cancer-related mortality worldwide, and non-small cell lung cancer (NSCLC) has the highest incidence [1,2]. Molecular targeted therapies, particularly epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), such as gefitinib, afatinib, and osimertinib, are currently standard treatments for patients with specific genetic aberrations in NSCLC [3,4]. While these therapies may initially yield favorable outcomes, their long-term efficacy is less consistent due to the inevitable development of drug resistance [5–7]. Such acquired resistance can emerge through a wide variety of EGFR-dependent (e.g., EGFR amplification) or EGFR-independent pathway mechanisms, such as MET amplification, small cell lung cancer (SCLC) transformation, and notably activation of epithelial-mesenchymal transition (EMT) [8–11].

Among these mechanisms, EMT is a complex biological process in which epithelial cells acquire mesenchymal features that lead to enhanced invasive and migratory abilities and significantly contribute to tumorigenesis, tumor metastasis, and resistance to anti-cancer therapies [12–16]. Recent evidence underscores the role of EMT in fostering resistance to a spectrum of treatments across various cancers, suggesting its potential as a target for therapeutic intervention [17,18]. In NSCLC, EMT has been implicated as a contributing factor to other targeted agents, including KRAS G12C inhibitors and ALK inhibitors [19,20]. However, the precise mechanisms by which EMT-dependent acquisition of EGFR-TKIs resistance occurs remain underexplored. Therefore, the identification of effective treatment strategies to target EMT-associated EGFR-TKIs resistance is a critical and unmet need to improve the clinical outcome of patients with NSCLC harboring EGFR-activating mutations.