Cell surface marker profiling of human tracheal basal cells reveals distinct subpopulations, identifies MST1/MSP as a mitogenic signal, and identifies new biomarkers for lung squamous cell carcinomas

Abstract

BackgroundThe large airways of the lungs (trachea and bronchi) are lined with a pseudostratified mucociliary epithelium, which is maintained by stem cells/progenitors within the basal cell compartment. Alterations in basal cell behavior can contribute to large airway diseases including squamous cell carcinomas (SQCCs). Basal cells have traditionally been thought of as a uniform population defined by basolateral position, cuboidal cell shape, and expression of pan-basal cell lineage markers like KRT5 and TP63. While some evidence suggests that basal cells are not all functionally equivalent, few heterogeneously expressed markers have been identified to purify and study subpopulations. In addition, few signaling pathways have been identified that regulate their cell behavior. The goals of this work were to investigate tracheal basal cell diversity and to identify new signaling pathways that regulate basal cell behavior.MethodsWe used flow cytometry (FACS) to profile cell surface marker expression at a single cell level in primary human tracheal basal cell cultures that maintain stem cell/progenitor activity. FACS results were validated with tissue staining, in silico comparisons with normal basal cell and lung cancer datasets, and an in vitro proliferation assay.ResultsWe identified 105 surface markers, with 47 markers identifying potential subpopulations. These subpopulations generally fell into more (~ > 13%) or less abundant (~ < 6%) groups. Microarray gene expression profiling supported the heterogeneous expression of these markers in the total population, and immunostaining of large airway tissue suggested that some of these markers are relevant in vivo. 24 markers were enriched in lung SQCCs relative to adenocarcinomas, with four markers having prognostic significance in SQCCs. We also identified 33 signaling receptors, including the MST1R/RON growth factor receptor, whose ligand MST1/MSP was mitogenic for basal cells.ConclusionThis work provides the largest description to date of molecular diversity among human large airway basal cells. Furthermore, these markers can be used to further study basal cell function in repair and disease, and may aid in the classification and study of SQCCs.Electronic supplementary materialThe online version of this article (doi:10.1186/s12931-014-0160-8) contains supplementary material, which is available to authorized users.

Identification of the SOX2 Interactome by BioID Reveals EP300 as a Mediator of SOX2-dependent Squamous Differentiation and Lung Squamous Cell Carcinoma Growth

“…EP300 was also expressed in ex vivo cultures of purified tracheobronchial basal cells that retain stem cell activity (Fig. 4C) (28,116). In primary patient SQCCs harboring SOX2 amplification that were grown as xenografts (PDXs), EP300 was expressed in most tumor cells, along with SOX2 (Fig.…”

Positional Integration of Lung Adenocarcinoma Susceptibility Loci with Primary Human Alveolar Epithelial Cell Epigenomes

“…A recent large-scale study of lung cancer susceptibility loci highlights the differences in genetic susceptibility between histological lung cancer subtypes [93]. Basal cells, which are airway epithelial cells that lie on the basement membrane and are thought to be involved in airway regeneration upon injury, are implicated as progenitors of squamous cell carcinoma [94,95]. Basal cells should be purified and epigenetically profiled in a similar fashion to the work described here.…”

δV1-1 Reduces Pulmonary Ischemia Reperfusion-Induced Lung Injury by Inhibiting Necrosis and Mitochondrial Localization of PKCδ and p53

“…We repeated experiments using human primary airway epithelial cells (38). Like BEAS-2B cells, cells retracted after 6-h CIT and recovered during reperfusion ( Figure S2A), whereas the number of attached cells decreased during reperfusion after 18-h CIT ( Figure S2A).…”