Protein Disulfide Isomerase Inhibition: A Novel Therapeutic Strategy against Pancreatic Cancer

Patients with pancreatic cancer have a very poor prognosis as the disease remains largely incurable. One-year relative survival rate is 20%, with five-year rate just 7%. Treatment is complex and depends on disease stage upon diagnosis. Most malignancies (80%) are unsuitable for surgery, thus chemotherapy is the primary treatment option. Identifying new treatments for pancreatic cancer remains a major clinical challenge.

The endoplasmic reticulum (ER) enzyme, protein disulfide isomerase (PDI), regulates cellular proteostasis, disruption of which causes ER-stress and apoptosis. Recently PDI was identified as a promising drug target for some cancers, including pancreatic cancer. However, little is known about how PDI inhibition impacts pancreatic cancer metabolism and proliferation.

Oregon Therapeutics and the University of Birmingham have identified a first-in-class compound that potently inhibits PDI activity and exhibits increased efficacy in chemo-resistant, compared to chemo-naive, pancreatic cancer. We propose to use in vitro and clinically-relevant in vivo models to understand how PDI inhibition impacts pancreatic cancer metabolism and proliferation, thus providing a foundation for the clinical development of PDI inhibitors. By combining our extensive pharmaceutical expertise, which covers all stages of drug development, we will:-
1) Delineate the mode-of-action and down-stream ER-stress effects of PDI-inhibition in pancreatic cancer.

2) Identify novel metabolic biomarkers of PDI inhibition in pancreatic cancer by measuring cellular redox homeostasis.

3) Pre-clinically test PDI inhibition using clinically translational murine models of pancreatic cancer.

Hypothesis:
PDI inhibition in pancreatic cancer will induce ER-stress, perturb metabolism, and cause apoptosis.

Experimental Methods and Research Plan:
ER-stress effects of PDI inhibition: The effect of PDI-inhibition on ER-stress in pancreatic cancer cell lines (PANC-1, Capan-2, HPAF-II, SW1990, AsPC-1) will be determined. We will measure downstream effects of PDI-inhibition on ER-stress by determining key protein and mRNA (IRE-phosphorylation, s-XBP-1, ATF4, eIF2, cyclin B1, CHOP, BiP) concentrations, as measured by immuno-blotting and qRT-PCR. PDI inhibition effects on apoptosis and cell-cycle arrest in pancreatic cancer cells will be measured via FACs. To demonstrate how loss of PDI activity effects ER-stress and apoptotic machinery we will use siRNA techniques to silence PDI activity in our cell lines.

PDI inhibition and pancreatic cancer metabolism: Through the Metabolic Tracer Analysis Core run by this projects 2nd supervisor (Dr Tennant), we will investigate how PDI inhibition effects the TCA cycle, NADH/HADPH homeostasis, and redox balance in pancreatic cancer cells. Results will allow for the potential identification of novel biomarkers for PDI inhibition.

Determine effects of PDI inhibition in mouse models of pancreatic cancer: To prepare PDI inhibitors for clinical trials, we will test its efficiacy and toxicitiy in SCID mice bearing human pancreatic cancer xenografts. Dr Foster (primary supervisor) has over 15 years experience in working with these models for pre-clinical drug development.

Applicants should have a strong background in molecular biology, and ideally a background in drug discovery. They should have skills with regard to western blotting, qRT-pCR, and cell culture. They should have a commitment to research in oncology and hold or realistically expect to obtain at least an Upper Second Class Honours Degree in a biomedical science subject.