CD9 identifies pancreatic cancer stem cells and modulates glutamine metabolism to fuel tumour growth.

Victoria M.-Y Wang,Emma L Nye,Theodore Evan,Jorge Almagro,Rute M M Ferreira,Eleanor Herbert,David J Barry,May Zaw Thin,Ambrosius P Snijders,Joana Carvalho,Axel Behrens,Nathalie Legrave,James I Macrae,David Frith

doi:10.1038/s41556-019-0407-1

Abstract

Pancreatic ductal adenocarcinoma (PDAC) shows great cellular heterogeneity, with pronounced epithelial and mesenchymal cancer cell populations. However, the cellular hierarchy underlying PDAC cell diversity is unknown. Here we identify the tetraspanin CD9 as a marker of PDAC tumour-initiating cells. CD9high cells had increased organoid formation capability, and generated tumour grafts in vivo at limiting dilutions. Tumours initiated from CD9high cells recapitulated the cellular heterogeneity of primary PDAC, whereas CD9low cells only produced duct-like epithelial progeny. CD9 knockdown decreased the growth of PDAC organoids, and heterozygous CD9 deletion in Pdx1-Cre; LSL-KRasG12D; p53F/F mice prolonged overall survival. Mechanistically, CD9 promoted the plasma membrane localisation of the glutamine transporter ASCT2, enhancing glutamine uptake in PDAC cells. Thus, our study identifies a PDAC subpopulation capable of initiating PDAC and giving rise to PDAC heterogeneity, suggesting that the cellular diversity of PDAC is generated by PDAC stem cell differentiation.

Highlights

We identify and characterise a tumour-initiating cells (TICs) population in Pancreatic ductal adenocarcinoma (PDAC) marked by high cell surface levels of the tetraspanin CD9
By prospective isolation of CD9expressing PDAC cells, we demonstrate that CD9 identifies TICs that re-initiate tumour formation and recapitulate the cellular heterogeneity of primary PDAC
To enrich for TIC function in vivo, we analysed very early stages of tumourigenesis, where cells of high tumourigenic potential presumably constitute a larger fraction of the tumour

Summary

Introduction

CD133 surface expression was detected in transformed and non-responsive cells (Extended Data Fig. 1c), excluding it as a specific TIC marker. Unlike CD44, high CD9 expression remained restricted to a subpopulation of KFCkY tumour cells at later stages of PDAC (Extended Data Fig. 1h-j). CD9 surface expression remained restricted to a subpopulation of cells in KPCY tumour organoids (Extended Data Fig. 1l).

Results

Conclusion