Abstract 2212: Cellular and molecular changes associated with lung squamous premalignant lesion severity identified by single-cell RNA-seq
Authors: Shea Conor , Kalinke Lukas , De Jong Kitty , Gowers Kate , Ding Diane , Zhang Sherry , Liu Gang , Cunningham Jack , Dey-Guha Ipsita , Hennon Mark , Yendumuri Sai , Stevenson Christopher , Dubinett Steven , Spira Avrum , Lenburg Marc , Janes Samuel , Reid Mary , Beane Jennifer , Mazzilli Sarah , Campbell Joshua D. 
Published: July 2021

Abstract
Background: Sampling the bronchial airway during bronchoscopies in screening populations at high risk for lung cancer has increased detection of squamous bronchial pre-malignant lesions (PML). The majority of these lesions will regress or remain stable without any clinical intervention. However, a subset of lesions will progress to invasive malignancy. In this work, we investigate the gene expression changes in epithelial cell states and immune cell proportion shifts associated with premalignant histologic stage using single-cell RNA sequencing to begin to identify molecular features associated with PML regression or progression.
Methods: Cells (n=3,325) were isolated from 11 endobronchial biopsies from 9 patients, where biopsy histology range from normal, dysplasia, carcinoma in situ (CIS) and squamous cell carcinoma. Immune cells (CD45+) and epithelial cells (CD45− EPCAM+) were sorted into separate 96-well plates using fluorescence activated cell sorting (FACS) and sequenced using CEL-Seq2 single cell RNA seq protocol.
Results: After filtering low quality cells, we profiled 2,998 cells (1,052 CD45+ and 1,946 CD45−) with an average of 1,190 genes per cell. Within the epithelial cells, we focused on basal cells as they are the airway progenitor cells. We observed distinct differences in expression of KRT5+ (basal) cells between different histologic grades, where KRT5+ cells present in a hyperplasic lesion expressed multiple secretory cell markers suggesting they were transitioning to a secretory cell phenotype and KRT5+ cells from a CIS lesion from a current smoker expressed higher levels of smoking inducible genes, such as GSTM1 and CYP1A1. Lastly, KRT5+ cells from a lung squamous carcinoma tumor expressed higher levels of many genes related to cell cycle progression. Among the immune populations, low-grade PMLs with non-dysplastic histology were enriched for CD8+ T cells, whereas higher-grade PMLs and an invasive tumor were enriched for myeloid cells.
Conclusions: To date, we have begun to identify histology-associated cellular and molecular profiles in bronchial premalignancy and early-stage carcinoma. Future resampling of these patients and expansion of cases will allow us to discover biomarkers associated with lesion progression and molecular targets for lung cancer interception.
Citation Format: Conor Shea, Lukas Kalinke, Kitty De Jong, Kate Gowers, Diane Ding, Sherry Zhang, Gang Liu, Jack Cunningham, Ipsita Dey-Guha, Mark Hennon, Sai Yendumuri, Christopher Stevenson, Steven Dubinett, Avrum Spira, Marc Lenburg, Samuel Janes, Mary Reid, Jennifer Beane, Sarah Mazzilli, Joshua D. Campbell. Cellular and molecular changes associated with lung squamous premalignant lesion severity identified by single-cell RNA-seq [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2212.