The Cancer Stem Cell Inhibitor Napabucasin (BBI608) Shows General Cytotoxicity in Biliary Tract Cancer Cells and Reduces Cancer Stem Cell Characteristics.

Marlena Beyreis,Markus Ritter,Tobias Kiesslich,Martin Gaisberger,Katharina Helm,Christian Mayr,Martin Jakab,Daniel Neureiter

doi:10.3390/cancers11030276

Marlena Beyreis, Markus Ritter + Show 6 more

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https://doi.org/10.3390/cancers11030276

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Journal: Cancers	Publication Date: Feb 26, 2019
Citations: 18	License type: CC BY 4.0

Affiliation: Paracelsus Medical University, Salzburger Landeskliniken

Abstract

Biliary tract cancer is a devastating disease with limited therapeutic options. The involvement of cancer stem cells in biliary tract cancer is likely. Napabucasin is a previously described cancer stem cell inhibitor that is currently being used in clinical trials. However, data regarding napabucasin and biliary tract cancer are not available yet. We tested the general cytotoxic effect of napabucasin on a comprehensive biliary tract cancer in vitro model, using resazurin assay and Annexin V/7-AAD staining. The effect of napabucasin on functional cancer stem cell characteristics was analyzed via soft agar assay, aldehyde-dehydrogenase-1 assay, measurement of surface CD326 expression, and measurement of clonogenic growth. The evaluation of the effect of napabucasin on cancer stem cell protein and gene expression was performed using Western blot and reverse transcription-PCR-based human cancer stem cell array. Napabucasin showed a concentration- and cell line-dependent cytotoxic effect, and increased the apoptotic and necrotic cell fractions. Treatment with napabucasin significantly reduced the formation of tumor spheres and clonogenic growth, as well as CD326 surface expression. Expression of cancer stem cell markers were reduced following napabucasin treatment on the protein and mRNA levels. Our study provides first data regarding napabucasin as a promising substance for the treatment of biliary tract cancer.

Highlights

Biliary tract cancer (BTC) is a rare and fatal disease originating from transformed cells of the bile duct system
We demonstrated that the inhibition of epigenetic regulators stopped BTC cell proliferation and inhibited putative Cancer stem cells (CSCs) subpopulations by reducing functional CSC
We show that napabucasin has a profound cytotoxic effect in BTC cells and significantly reduces functional CSC characteristics, protein, and mRNA expression of CSC-related factors

Summary

Introduction

Biliary tract cancer (BTC) is a rare and fatal disease originating from transformed cells of the bile duct system. Cancer stem cells (CSCs) are defined as a cell population within the heterogeneous tumor mass that possess the abilities to self-renew and to differentiate into different (tumor cell) lineages. They are linked to tumor initiation, progression, resistance, and poor prognosis [3]. Chemotherapeutics may reduce the tumor mass of BTC, the resistance of CSC towards these treatments most probably hinders long-term success and leads to tumor regrowth, making CSCs an attractive therapeutic target in BTC [8]. We demonstrated that the inhibition of epigenetic regulators stopped BTC cell proliferation and inhibited putative CSC subpopulations by reducing functional CSC characteristics, like sphere formation and aldehyde-dehydrogenase 1 (ALDH1)-positivity [9,10]

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