Distinct fibroblast subpopulations associated with bone, brain or intrapulmonary metastasis in advanced non‐small‐cell lung cancer

Abstract Background Bone or brain metastases may develop in 20–40% of individuals with late‐stage non‐small‐cell lung cancer (NSCLC), resulting in a median overall survival of only 4–6 months. However, the primary lung cancer tissue's distinctions between bone, brain and intrapulmonary metastases of NSCLC at the single‐cell level have not been underexplored. Methods We conducted a comprehensive analysis of 14 tissue biopsy samples obtained from treatment‐naïve advanced NSCLC patients with bone ( n = 4), brain ( n = 6) or intrapulmonary ( n = 4) metastasis using single‐cell sequencing originating from the lungs. Following quality control and the removal of doublets, a total of 80 084 cells were successfully captured. Results The most significant inter‐group differences were observed in the fraction and function of fibroblasts. We identified three distinct cancer‐associated fibroblast (CAF) subpopulations: myofibroblastic CAF (myCAF), inflammatory CAF (iCAF) and antigen‐presenting CAF (apCAF). Notably, apCAF was prevalent in NSCLC with bone metastasis, while iCAF dominated in NSCLC with brain metastasis. Intercellular signalling network analysis revealed that apCAF may play a role in bone metastasis by activating signalling pathways associated with cancer stemness, such as SPP1‐CD44 and SPP1‐PTGER4. Conversely, iCAF was found to promote brain metastasis by activating invasion and metastasis‐related molecules, such as MET hepatocyte growth factor. Furthermore, the interaction between CAFs and tumour cells influenced T‐cell exhaustion and signalling pathways within the tumour microenvironment. Conclusions This study unveils the direct interplay between tumour cells and CAFs in NSCLC with bone or brain metastasis and identifies potential therapeutic targets for inhibiting metastasis by disrupting these critical cell–cell interactions.