Investigation of the effect of disulfiram on the chemoresistance and invasiveness in pancreatic cancer cells

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers worldwide with a mortality to incidence ratio of 94%. It is the 10th most common cancer in the UK with a 5-year survival less than 7%. In contrast to the improved therapeutic outcomes in many other cancers, the prognosis of PDAC remains dismal. One reason for this is because most PDAC patients are asymptomatic and end up being diagnosed after the cancer has advanced to a late stage. Another major obstacle in PDAC management is that PDAC cells are highly resistant to currently available anticancer drugs and the resistant cells metastasize to vital organs leading to a high rate of fatalities. Cancer stem cells (CSCs) are responsible for chemoresistance, relapse and metastasis. It is widely accepted that CSCs are located in the hypoxic niche which is responsible for maintaining stemness and epithelial to mesenchymal transition (EMT). The stemness of cancer cells is a reversible state mediated by the hypoxic tumour microenvironment. Hypoxia initiates stemness in cancer cells by activating genes which inhibit apoptosis, modify glucose metabolism, increase cell proliferation and enhance cell pluripotency. Therefore, development of new drugs to target hypoxia-induced CSCs will be of clinical urgency in PDAC treatment. Due to the time and costs for new drug development, repositioning of old drugs for new ailments is an emerging drug R&D strategy in recent years. Disulfiram (DS) is an anti-alcoholism drug used in clinic for over 60 years. It demonstrates excellent activity against a wide range of cancers such as glioblastoma, non-small cell lung cancer and, head and neck squamous cell carcinoma without toxicity to normal cells. Whereas, its effect on PDAC cells is still largely unknown. In this study, the in vitro effect of hypoxia on the stemness, chemosensitivity and invasiveness of Panc-1, a PDAC cell line, and a panel of patient-derived PDAC primary cultures was investigated. The sphere-cultured PDAC cells contained high hypoxic population which demonstrated CSC/EMT traits and were resistant to the first line anti-PDAC drugs; gemcitabine and paclitaxel. The study manifested that the hypoxia-cultured monolayer PDAC cell line and primary cells also expressed CSC markers, ‘ALDH, CD133, ABCG2’ and EMT markers, ‘Vimentin, Snail1, N-cadherin, Snail2’. The hypoxia-cultured cells were highly resistant to gemcitabine and paclitaxel. Significantly higher migration and invasion activities were detected in the hypoxia-cultured PDAC cells compared to the normoxic cultures. Our previous studies demonstrated that copper is essential for the anticancer activity of DS. In this study, the effect of cyclodextrin encapsulated DS and copper (CycDex DS/Cu) on PDAC cells was examined. In line with previous studies, CycDex DS/Cu showed strong cytotoxicity in sphere- and hypoxia-cultured PDAC cells. It blocked hypoxia-induced CSC/EMT traits and reversed hypoxia-induced chemoresistance to gemcitabine and paclitaxel in PDAC cells. DS is an FDA approved medicine. The study suggests that further studies may translate it into PDAC clinic application in a fast track. Many hypotheses claim that hypoxia activates NFкB which in turn activates a cascade of genes that promote metastasis and chemoresistance in cancer. Our previous results indicate that NFкB plays a key role in chemoresistance and invasiveness in some types of cancer. For these reasons, the effect of NFкB on PDAC cells was investigated, NFкBp65 was genetically overexpressed and knocked out in Panc-1 PDAC cell line. The NFкBp65 overexpressed clones showed significantly higher migration rate but failed to induce chemoresistance. In contrast to our previous findings, the NFкBp65 overexpression and knockout did not influence the expression of CSC/EMT markers. These results suggest that we still need to set up further studies to elucidate the molecular anti-PDAC mechanisms of cyclodextrin encapsulated DS/Cu in PDAC cells.

Citation

Nkeonye, O. (2022) Investigation of the effect of disulfiram on the chemoresistance and invasiveness in pancreatic cancer cells. University of Wolverhampton. http://hdl.handle.net/2436/624947

Publisher

University of Wolverhampton

URI

http://hdl.handle.net/2436/624947

Type

Thesis or dissertation

Language

en

Description

A thesis submitted in partial fulfilment for the degree of Doctor of Philosophy in Molecular Oncology.

Rights

Attribution-NonCommercial-NoDerivatives 4.0 International

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Collections

Theses and Dissertations