Intratumoral Heterogeneity and Immune Modulation in Lung Adenocarcinoma in Female Smokers and Never Smokers

Abstract

Lung cancer remains the leading cause of cancer-related death worldwide, despite declining smoking prevalence in industrialized countries. Although lung cancer is highly associated with smoking status, a significant proportion of lung cancer cases develop in patients who have never smoked, with an observable bias toward female never smokers. A better understanding of lung cancer heterogeneity and immune system involvement during tumor evolution and progression in never smokers is therefore highly needed. Here, we used single-nucleus transcriptomics of surgical lung adenocarcinoma (LUAD) and normal lung tissue samples from patients with or without a history of smoking. Immune cells as well as fibroblasts and endothelial cells responded to tobacco smoke exposure by inducing a highly inflammatory state in normal lung tissue. In LUAD, characterization of differentially expressed transcriptional programs in macrophages and cancer-associated fibroblasts provided insight into how the niche favors tumor progression. Within tumors, eight subpopulations of neoplastic cells were identified in female smokers and never smokers. Pseudotemporal ordering inferred a trajectory toward two differentiated tumor cell states implicated in cancer progression and invasiveness. A proliferating cell population sustaining tumor growth exhibited differential immune modulating signatures in both patient groups. Collectively, these results resolve cellular heterogeneity and immune interactions in LUAD, with a special emphasis on female never smokers.