Poster Presentation 35th Lorne Cancer Conference 2023

Targeting the urokinase plasminogen activator (uPA) inhibits cell-surface plasmin turnover and metastasis in pancreatic ductal adenocarcinoma: A preclinical drug target validation study (#213)

Ashna A Kumar 1 2 , Benjamin Buckley 1 2 , S M Zahid Hosen 3 4 , Zhihong Xu 3 4 , Minoti Apte 3 4 , Marie Ranson 1 2
  1. School of Chemistry and Molecular Bioscience , University of Wollongong, Wollongong, NSW, Australia
  2. Illawarra Health and Medical Research Institute , Wollongong, NSW, Australia
  3. Ingham Institute for Applied Medical Research, Sydney, NSW, Australia
  4. Pancreatic Research Group, University of New South Wales , Sydney , NSW, Australia

Metastasis accounts for 90% of all cancer-related deaths. The metastatic cascade in multiple cancer types is facilitated by the urokinase plasminogen activator (uPA), a cell-surface mediator of extracellular matrix degradation and tumour cell invasiveness, via the activation of plasminogen into the serine protease plasmin. Pancreatic ductal adenocarcinoma (PDAC) has among the worst prognosis of all solid malignancies and is characterised by high metastatic burden at diagnosis. High uPA expression in locally advanced PDAC patient tumours is significantly associated with poorer survival. We previously developed novel, non-cytotoxic 5- and 6-substituted amiloride analogues that potently inhibit human uPA activity and were effective in inhibiting metastasis in an orthotopic xenograft model of PDAC. Here, we validate the cell-surface expression of uPA and its receptor (uPAR) in human and murine PDAC cell-lines AsPC-1 and KPCs, respectively, via flow cytometry, and their efficiency in generating cell-surface plasmin. In addition, we validate the inhibition of cell-surface plasminogen activation by small-molecule uPA-selective inhibitor BB2-30F in whole-cell assays of plasmin activity. We also apply matrix assisted laser desorption/ionisation mass spectrometry imaging (MALDI-MSI) to assess and visualise BB2-30F uptake and spatial distribution in ex-vivo murine tumour sections from the aforementioned orthotopic xenograft model of PDAC. Our data confirms high endogenous uPA and uPAR expression in AsPC-1 and KPC cells, whereby elevated uPA levels enhance plasminogen activation. Furthermore, cell-surface plasmin activity was significantly diminished by BB2-30F treatment in a dose-dependent manner. In preliminary MALDI-MSI work, a signal consistent with the m/z of protonated BB2-30F (m/z 386.2045) was observed in treated tissue, relative to the control tissue. Furthermore, the drug signal intensity was heterogenous in histological compartments of tumour tissue sections, which could correlate to regions of drug target (uPA) rich areas of tissue. Future work will encompass parallel examination of histology, such as H&E staining and immunohistochemistry, in adjacent tumour sections to correlate the localisation of uPA, a key biomarker of cancer biology, with tissue drug disposition. In summary, our results validate the efficacy of uPA targeting approaches as a therapeutic opportunity to limit metastatic potential in PDAC.