Abstract

Aims Lipid-associated macrophages are a specific subpopulation of macrophages that play a crucial role in cancer progression and treatment resistance. However, the functional impact of lipid-associated macrophages in lung adenocarcinoma (LUAD) remains poorly understood. This study aims to investigate the role and underlying mechanisms of lipid-associated macrophages in LUAD liver metastasis and resistance to osimertinib, a third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI). Methods Single-cell RNA sequencing (scRNA-seq) was performed on human lung tumor tissues from patients with primary LUAD and those with LUAD liver metastasis, which identified a novel subpopulation of stabilin-1 (STAB1) + lipid-associated macrophages. The influence of STAB1 + lipid-associated macrophages on LUAD liver metastasis and osimertinib resistance was evaluated in vitro and in vivo . An in vitro co-culture system was established to investigate the interaction between LUAD cells and lipid-associated macrophages, and the mechanisms were analyzed by RNA-seq, Luminex multi-factor detection, Co-IP, in vivo , and rescue experiments. Results The subpopulation of STAB1 + lipid-associated macrophages was more abundant in liver metastatic LUAD tumors than in primary tumors. This lipid-associated macrophage subpopulation exhibited a stronger ability of lipid uptake from tumors and lipid droplet accumulation. We found that C-X-C motif ligand 12 (CXCL12) chemokine secreted by liver metastatic LUAD cells was responsible for recruiting circulating monocytes and subsequently inducing their differentiation into STAB1 + lipid-associated macrophages. STAB1 overexpression impaired the phagocytic ability of macrophage towards dying tumor cells by upregulating the signal regulatory protein α (SIRPα)-CD47 “don’t eat me” signal. In tumor xenograft models, inhibition of STAB1 + lipid-associated macrophages effectively suppressed LUAD osimertinib resistance and liver