Suppression of pancreatic cancer liver metastasis by secretion-deficient ITIH5

Alexander E Shearin,Sharon J Manley,Rosalyn Zimmerman,Carolyn J Vivian,Ken Sasaki,Aishwarya Parasuram,Maura O’Neil,Danny R Welch,Tomoo Iwakuma,Eric D Young,Michael A Hollingsworth,Evan Kauffman,Paul M Grandgenett,Thomas C Beadnell

doi:10.1038/s41416-020-01093-z

Abstract

BackgroundPreviously, we identified ITIH5 as a suppressor of pancreatic ductal adenocarcinoma (PDAC) metastasis in experimental models. Expression of ITIH5 correlated with decreased cell motility, invasion and metastasis without significant inhibition of primary tumour growth. Here, we tested whether secretion of ITIH5 is required to suppress liver metastasis and sought to understand the role of ITIH5 in human PDAC.MethodsWe expressed mutant ITIH5 with deletion of the N-terminal secretion sequence (ITIH5Δs) in highly metastatic human PDAC cell lines. We used a human tissue microarray (TMA) to compare ITIH5 levels in uninvolved pancreas, primary and metastatic PDAC.ResultsSecretion-deficient ITIH5Δs was sufficient to suppress liver metastasis. Similar to secreted ITIH5, expression of ITIH5Δs was associated with rounded cell morphology, reduced cell motility and reduction of liver metastasis. Expression of ITIH5 is low in both human primary PDAC and matched metastases.ConclusionsMetastasis suppression by ITIH5 may be mediated by an intracellular mechanism. In human PDAC, loss of ITIH5 may be an early event and ITIH5-low PDAC cells in primary tumours may be selected for liver metastasis. Further defining the ITIH5-mediated pathway in PDAC could establish future therapeutic exploitation of this biology and reduce morbidity and mortality associated with PDAC metastasis.

Highlights

We identified ITIH5 as a suppressor of pancreatic ductal adenocarcinoma (PDAC) metastasis in experimental models
In the ITIH5 and ITIH5Δs groups, we detected the C-terminal fragment at ~75 kDa, and an N-terminal fragment (~45 kDa) due to 17 AA added after the ORF and a FLAG tag before the STOP codon in the expression construct (Fig. 1b)
In contrast to our original hypothesis that secretion of ITIH5 is required for suppression of liver metastasis, we show that secretion of ITIH5 may not be necessary for suppression of liver metastasis in PDAC

Summary

Introduction

We identified ITIH5 as a suppressor of pancreatic ductal adenocarcinoma (PDAC) metastasis in experimental models. Expression of ITIH5 correlated with decreased cell motility, invasion and metastasis without significant inhibition of primary tumour growth. We tested whether secretion of ITIH5 is required to suppress liver metastasis and sought to understand the role of ITIH5 in human PDAC. METHODS: We expressed mutant ITIH5 with deletion of the N-terminal secretion sequence (ITIH5Δs) in highly metastatic human PDAC cell lines. RESULTS: Secretion-deficient ITIH5Δs was sufficient to suppress liver metastasis. Similar to secreted ITIH5, expression of ITIH5Δs was associated with rounded cell morphology, reduced cell motility and reduction of liver metastasis. In human PDAC, loss of ITIH5 may be an early event and ITIH5-low PDAC cells in primary tumours may be selected for liver metastasis.

Methods

Results

Conclusion