Background: Tumor histology reflects disease aggressiveness and clinical outcomes in cancer patients. Lung adenocarcinomas (LUADs) are classified based on predominant histologic patterns, including high-grade micropapillary and solid subtypes which portend unfavorable clinical features and prognosis. However, the cellular and molecular characteristics underlying these histologic subtypes remain largely unknown.

Methods: We used scRNA-seq to profile 117,266 cells from 18 treatment-naïve LUADs with heterogeneous histologic patterns and also performed spatial transcriptomic analysis (10x Visium) for representative cases. By integrating single-cell transcriptomics with spatial information, we aimed to characterize the cellular identity and spatial organization driving LUAD heterogeneity.

Results: We demonstrated that histologic subtypes can be distinguished by subtype-specific cancer cell subpopulations and immunosuppressive phenotypes in the tumor microenvironment (TME). Our data reveal how intercellular interactions among cancer cells, macrophages, and CD8+ T cells in the prognostically unfavorable solid subtype are associated with cancer cell plasticity and promote an immunosuppressive TME. Additionally, we identify HMGA1 as a potential clinically relevant biomarker and therapeutic target for the solid subtype LUAD.

Conclusions: These findings deepen our understanding of the histologic heterogeneity of LUAD and may facilitate the development of subtype-specific biomarkers and targeted therapeutic strategies.

Keywords: Histologic subtypes; Lung adenocarcinoma; Spatial tanscriptomics; scRNA-seq.