MYC recruits tumor-associated macrophage to sustain metastatic malignancy of lung adenocarcinoma micropapillary subtype through epigenetic reprogramming

Current comprehension of micropapillary lung adenocarcinoma (MP-LUAD) remains circumscribed to the realms of biological behaviors and genomic landscapes. Previous studies from our institute have shown that there exist subtle and unactionable genomic alterations between MP and non-MP early-stage lung adenocarcinoma (LUAD). Therefore, deciphering the unknown non-genomic regulatory network of MP-pattern malignancy may offer opportunities to uncover more tractable therapeutic targets for MP-LUAD patients.Bulk RNA-seq after microdissection showed aberrant activation of the MYC pathway in MP. The CDX mouse model showed that MYC overexpression induced a MP-pattern malignancy in tumor tissues, but in vitro experiments lacked consistency. Through screening via single-cell RNA-se, retrospective cohort and TCGA dataset, we found aberrant accumulation of tumor-associated macrophages (TAMs) around MP tissues. in vitro co-culture and in vivo dependency experiments demonstrated that MYC overexpression in tumor cells exhibited a MP-pattern malignancy in collaboration with TAMs. Follow-up experiments revealed that, MYC interacts with the pioneer transcription factor FOSL2 induced by TGFβ secreted from TAMs, transcriptionally regulating the expression of MP-pattern genes.Our study uncovered copy number amplification-induced activation of MYC in MP-LUAD, which by recruiting TAMs, cooperatively transcriptionally regulates MP pattern genes and promotes a metastatic malignancy. Bulk RNA-seq was performed on microdissected RNA samples from 3 lung adenocarcinoma tissues containing micropapillary and acinar components. RNA-seq was also performed on A549 cell line samples subjected to the following manipulations: 1) transfection with pcDNA3 control plasmid, 2) transfection with MYC overexpression plasmid, 3) transfection with pcDNA3 control plasmid and co-culture with M2-like macrophages for 72 hours, 4) transfection with MYC overexpression plasmid and co-culture with M2-like macrophages for 72 hours. Anti-H3K27ac CUT&Tag-seq was performed on microdissected samples from 1 lung adenocarcinoma tissues containing micropapillary and acinar components. A549 cell line samples were subjected to the following manipulations: 1) transfection with pcDNA3 control plasmid, 2) transfection with MYC overexpression plasmid, 3) transfection with pcDNA3 control plasmid and co-culture with M2-like macrophages for 72 hours, 4) transfection with MYC overexpression plasmid and co-culture with M2-like macrophages for 72 hours. Anti-cMyc ChIP-seq was performed on microdissected DNA samples from 1 lung adenocarcinoma tissue containing a micropapillary component as well as on DNA samples from A549 cell line transfected with MYC overexpression plasmid and co-cultured with M2-like macrophages for 72 hours.