Single Cell RNA Sequencing Unravel Intratumoral Heterogeneity Of Lung Adenocarcinoma Featured As Mixed Ground-Glass Opacity

Background:Accompanied by the popularity of LDCT(low-dose computed tomography),GGO(ground glass opacity)has been increasingly detected.GGOs with indolent behavior are usually diagnosed as early IAC(invasive adenocarcinoma)or pre-invasive lesions.The high incidence of GGO is raising up both economic and psychological burdens of citizens.Among the lung adenocarcinoma featured by GGO,m GGO(mixed ground glass opacity)behave as coexistence of solid part and GG part.The malignancy rate of m GGO is higher than p GGO(pure ground glass opacity).However,the transcriptomics and TME(tumor microenvironment)of intra-tumor heterogeneity remain poorly understood.This study depicted the differences between solid part and GG part using single-cell sequence and attempted to unravel the dynamic changes of TME and transcriptomic features during the development of early lung adenocarcinoma.Method:We dissected nodules from three patients with similar tumor size and a clear margin between solid part and GG part,using macro-dissection based on localization of CT images and area identity by naked eye during the operation.The solid part and GG part is then going through single-cell sequence,together with Immunohistochemistry and immunofluorescence assay,to explore the mechanism of m GGO development.Outcome:19,391 single-cell profiles were taken into analysis.Cell atlas reveals that cancer cells and macrophages were the dominant cell types in the solid(S)and ground-glass(GG)components of m GGO,respectively.We found that cancer cells simultaneously expressed markers of the alveolar type I cells(AT1)and alveolar type II cells(ATII).Cancer cells in the solid components expressed higher tumor-associated markers and harbored higher immunogenicity comparing to GG components.Meanwhile,they downregulated the expression of surfactant proteins(SFTPA1,SFTPA2,SFTPC,SFTPD)comparing to cancer cells in the GG components.In most cases,cancer cells in the solid components are likely to originate from the GG components or from the so called lepidic growth cancer cells.However,the solid components could also contain stem-like cancer cells that gave rise to novel subclones.Inflammatory macrophages featured as high expression level of SPP1 were enriched in the solid components.They upregulated factors such as CCL3,CCL4 and CXCL8 to display its role in inflammatory cell chemoattraction.The GG component macrophages showed stronger antimicrobial function in comparison with macrophages in the S components.Moreover,they expressed higher level of the core proteins consist of stress granules such as G3BP2.Cell-cell interactions is rewiring between the different components of m GGO,indicating that the distinct tumor microenvironment might be critical in the diverse growing behaviors across the different components.Conclusion:We demonstrated distinct cell atlas,single-cell transcriptome features and cell-cell interaction networks across the S and GG components of m GGO.Our findings provided a deeper knowledge of diverse behaviors across the different components in lung adenocarcinoma featured as m GGO.