P59.07 Molecular Profiling of Human Non-Small Cell Lung Cancer by Single-Cell RNA-Seq

Abstract

Lung cancer is one of the malignant tumors with the highest morbidity and mortality worldwide. As the lung is a complex organ composed of more than 40 different types of cells, which contribute to the heterogeneity of lung cancers at tumor initiation, it is important to separate different cell types to profile their characteristics. In this study, we aim to comprehensively analyze the molecular heterogeneity of non-small-cell lung cancer (NSCLC). We performed single-cell RNA-seq analyses on 7,364 individual cells from tumor tissues and matched normal tissues from 19 primary lung cancer patients and 1 pulmonary chondroid hamartoma patient. We identified a significant proportion of cancer cells simultaneously expressing classical marker genes for two or three histologic subtypes of NSCLC—adenocarcinoma (ADC), squamous cell carcinoma (SCC), and large cell neuroendocrine carcinoma (LCNEC) in the same individual cell; this was verified by coimmunostaining and RNA in situ hybridization. These data suggest that mixed-lineage tumor cells are highly plastic with mixed features of different types of NSCLC. Both copy number variation (CNV) patterns and mitochondrial mutations clearly showed that the mixed-lineage and single-lineage tumor cells from the same patient had common tumor ancestors rather than different origins. Moreover, we revealed that patients with high mixed-lineage features of different cancer subtypes had worse survival than patients with low mixed-lineage features, indicating that mixed-lineage tumor features were associated with poorer prognosis. Based on the pseudotime trajectory of gene expression dynamics from normal epithelial cells to cancer cells, a cancer-specific gene set has been identified, which includes AKR1B1 and RAMP1. Knockdown experiments verified that both AKR1B1 and RAMP1 were necessary for tumor growth, suggesting that they can serve as candidate targets for tumor therapy. Our work provides novel insights into the heterogeneity of NSCLC and offers clues for the more refined classification, diagnosis and treatment of each subtype.