Characterization of Stem-like Circulating Tumor Cells in Pancreatic Cancer.

Lei Zhu,Johann-Christoph Jann,Barbara Hissa,Christoph Reissfelder,Sebastian Schölch,Cui Yang,Balázs Győrffy

doi:10.3390/diagnostics10050305

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is the fourth most frequent cause of death from cancer. Circulating tumor cells (CTCs) with stem-like characteristics lead to distant metastases and thus contribute to the dismal prognosis of PDAC. Our purpose is to investigate the role of stemness in CTCs derived from a genetically engineered mouse model of PDAC and to further explore the potential molecular mechanisms. The publically available RNA sequencing dataset GSE51372 was analyzed, and CTCs with (CTC-S) or without (CTC-N) stem-like features were discriminated based on a principal component analysis (PCA). Differentially expressed genes, weighted gene co-expression network analysis (WGCNA), and further functional enrichment analyses were performed. The prognostic role of the candidate gene (CTNNB1) was assessed in a clinical PDAC patient cohort. Overexpression of the pluripotency marker Klf4 (Krüppel-like factor 4) in CTC-S cells positively correlates with Ctnnb1 (β-Catenin) expression, and their interaction presumably happens via protein–protein binding in the nucleus. As a result, the adherens junction pathway is significantly enriched in CTC-S. Furthermore, the overexpression of Ctnnb1 is a negative prognostic factor for progression-free survival (PFS) and relapse-free survival (RFS) in human PDAC cohort. Overexpression of Ctnnb1 may thus promote the metastatic capabilities of CTCs with stem-like properties via adherens junctions in murine PDAC.

Highlights

With 57,000 new cases and 46,000 deaths annually, pancreatic ductal adenocarcinoma (PDAC) is the 9th most frequent malignant disease in males and 8th most prevalent in females and the 4th most frequent cause of death in both genders [1]
According to the principal component analysis (PCA) loading plot (Figure 2A), the cluster located in the first quadrant exhibited stemness markers and was defined as circulating tumor cells (CTCs)-S (CTCs with stem-like features) (Figure 2B)
We performed an integrated bioinformatic analysis of single-cell RNA sequencing data of pancreatic CTCs derived from the genetically induced mouse models (GEMMs)

Summary

Introduction

With 57,000 new cases and 46,000 deaths annually, pancreatic ductal adenocarcinoma (PDAC) is the 9th most frequent malignant disease in males and 8th most prevalent in females and the 4th most frequent cause of death in both genders [1]. CTCs are shed from the primary tumor, survive in circulation, and colonize distant organs where they establish clinically overt metastases [9,16]. In order to achieve the invasive phenotype required to leave the primary tumor bulk and enter circulation, CTCs from epithelial tumors undergo a process called epithelial–mesenchymal transition (EMT). During this process, the cells acquire mesenchymal properties (e.g., migratory capability) while downregulating epithelial traits [20,21]. As both EMT and MET dynamically fluctuate, CTCs in circulation exhibit a high degree of plasticity and represent a heterogeneous population consisting of epithelial, mesenchymal, and intermediary cells [20,22]

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