Investigation of anti-cancer activity of disulfiram in primary pancreatic ductal adenocarcinoma (PDAC) cells


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Ogechi Nkeonye1,Vinodh Kannappan1,Kate Butcher1,Karim Azar1,Rajagopal Sharada Kilari2,Mark Morris1,Christopher McConville3,Christopher Heeschen4,Weiguang Wang1

1University of Wolverhampton,2University of Birmingham,3Barts Cancer Institute

Abstract

Background

PDAC is the 4th most common malignancy with very dismal prognosis. PDAC contains cancer stem cells (CSCs), which are highly metastatic and resistant to chemotherapies becoming the primary source of PDAC relapse. CSCs are commonly located in hypoxic regions. Our previous studies demonstrated that both hypoxia and NFκB pathway activation were co-detected in cells expressing CSC markers isolated from the core region of tumour spheres. High NFκB activity may play a pivotal role in hypoxia-induced CSC characteristics and chemoresistance. Therefore, targeting hypoxia-induced NFkB and CSCs will improve the therapeutic outcomes. Disulfiram (DS), an antialcoholism medicine, inhibits NFkB pathway, targets CSCs and demonstrates strong anticancer activity in several types of cancer in a copper (Cu) dependent manner. Here, we investigated the cytotoxicity of DS in a panel of primary pancreatic cancer cells and its effect on CSCs.

Method

MTT, CSC marker detection, PDAC cell spheroid culture, hypoxic culture and sphere re-formation.

Results

Six primary PDAC cells were examined. The hypoxia-cultured PDAC cells are highly resistant to gemcitabine (dFdC) and paclitaxel (PTX). All PDAC cells cultured in hypoxia have higher ALDH activity and express higher levels of CD133. DS/Cu demonstrates comparable toxicity in both normoxic and hypoxic cells. DS/Cu also enhances the cytoxicity of dFdC and PTX, and reverses the hypoxia-induced chemoresistance. Isobologram assay indicates strong synergistic effect between dFdC, PTX and DS/Cu. Sphere-reformation assay shows that spheroid culture induces resistance to dFdC and PTX. In contrast, DS/Cu completely blocks the sphere reforming ability in PDAC cells. DS/Cu also inhibits the ALDH activity and the expression of CD133 in hypoxia and sphere cultured PDAC cells.

Conclusion

The preliminary results from this study indicate that DS/Cu is a strong CSC inhibitor in PDAC primary cells. In combination with DS/Cu, the toxicity of the conventional first line anti-PDAC drugs could be synergistically enhanced.