Pancreatic cancer circulating tumour cells express a cell motility gene signature that predicts survival after surgery

Abstract

BackgroundMost cancer deaths are caused by metastases, resulting from circulating tumor cells (CTC) that detach from the primary cancer and survive in distant organs. The aim of the present study was to develop a CTC gene signature and to assess its prognostic relevance after surgery for pancreatic ductal adenocarcinoma (PDAC).MethodsNegative depletion fluorescence activated cell sorting (FACS) was developed and validated with spiking experiments using cancer cell lines in whole human blood samples. This FACS-based method was used to enrich for CTC from the blood of 10 patients who underwent surgery for PDAC. Total RNA was isolated from 4 subgroup samples, i.e. CTC, haematological cells (G), original tumour (T), and non-tumoural pancreatic control tissue (P). After RNA quality control, samples of 6 patients were eligible for further analysis. Whole genome microarray analysis was performed after double linear amplification of RNA. ‘Ingenuity Pathway Analysis’ software and AmiGO were used for functional data analyses. A CTC gene signature was developed and validated with the nCounter system on expression data of 78 primary PDAC using Cox regression analysis for disease-free (DFS) and overall survival (OS).ResultsUsing stringent statistical analysis, we retained 8,152 genes to compare expression profiles of CTC vs. other subgroups, and found 1,059 genes to be differentially expressed. The pathway with the highest expression ratio in CTC was p38 mitogen-activated protein kinase (p38 MAPK) signaling, known to be involved in cancer cell migration. In the p38 MAPK pathway, TGF-β1, cPLA2, and MAX were significantly upregulated. In addition, 9 other genes associated with both p38 MAPK signaling and cell motility were overexpressed in CTC. High co-expression of TGF-β1 and our cell motility panel (≥ 4 out of 9 genes for DFS and ≥ 6 out of 9 genes for OS) in primary PDAC was identified as an independent predictor of DFS (p=0.041, HR (95% CI) = 1.885 (1.025 – 3.559)) and OS (p=0.047, HR (95% CI) = 1.366 (1.004 – 1.861)).ConclusionsPancreatic CTC isolated from blood samples using FACS-based negative depletion, express a cell motility gene signature. Expression of this newly defined cell motility gene signature in the primary tumour can predict survival of patients undergoing surgical resection for pancreatic cancer.Trial RegistrationClinical trials.gov NCT00495924

Downstream of Mutant KRAS, the Transcription Regulator YAP Is Essential for Neoplastic Progression to Pancreatic Ductal Adenocarcinoma

“…Through a metaanalysis of published human PDAC microarray data sets (74–77), we confirmed that overall YAP mRNA abundance was significantly increased in human PDAC when compared to normal pancreatic tissues (fig. S1A).…”

Opportunities and Challenges for Pancreatic Circulating Tumor Cells

“…The researchers then performed whole-genome microarray analysis and identified a gene expression signature for motile CTCs. They found that high expression levels of the combination of the transforming growth factor-β gene and 9 other genes that regulate cell motility increased chances for disease-free survival (hazard ratio, 1.885 compared to patients with cells without this expression pattern) and overall survival (hazard ratio, 1.366 compared to patients with cells without this expression pattern) 106 .…”

Clinical Significance of Circulating Tumor Cells in Pancreatic Cancer

“…In a clinical trial (NCT00495924), Sergeant et al attempted to use gene expression signature of CTCs to predict survival for pancreatic cancer patients who underwent surgical tumor resection. The high co-expression of TGF-β1 and a group of 9 genes function in cell motility were found to be independent markers to predict the PFS and OS [17]. Taken together, many studies have reported promising results to support the use of CTCs as a prognostic marker in PC.…”

“…Sergeant and his colleagues registered the first CTC trial in PC in clinicaltrials.gov (NCT00495924). The aim of this study is to develop a CTC gene signature for assessing its prognostic relevance with surgical operation in PDAC patients [17]. Using FACS-based method, CTCs was enriched from the blood of 10 patients who underwent surgery for PDAC.…”