Influence of freeze-drying on the recovery of the tumour invasion markers uPA and PAI-1 from prostate cancer resections

Abstract

Background: Urokinase plasminogen activator (uPA) and its inhibitor (PAI-1) have been shown to be of merit as biomarkers for a variety of cancers. Prostate tissue resections from patients with prostate cancer (PCa) and benign prostatic hyperplasia were analysed to determine the influence of freeze-drying on the recovery of uPA and PAI-1 and their predictive performance. Methods: Prostate tissue was frozen in liquid nitrogen and homogenised into a fine powder in a precooled stainless steel punch homogeniser. One aliquot of the powder was extracted directly, and a second aliquot was freeze-dried overnight and then extracted. The extracts were analysed by FEMTELLE assay to determine the concentrations of uPA and PAI-1. uPA/PAI-1 ratios were calculated for each sample, and the mean ratios for the frozen and the lyophilised tissue were compared. Results: The concentrations of uPA measured for the frozen and lyophilised samples are strongly correlated (R ¼ 0.90 AE 0.05). The same applies to the PAI-1 measured (R ¼ 0.89 AE 0.03). The uPA/PAI-1 ratios for the lyophilised and frozen samples were strongly correlated. The uPA/PAI-1 ratios for frozen and lyophilised samples were found to be essentially the same with values of 0.0344 AE 0.0066 and 0.0340 AE 0.0068, respectively (P ¼ 0.9633). Conclusion: The recovery of uPA and PAI-1 from a deep frozen prostate tissue homogenate followed by freeze-drying proceeds with a loss of 10 and 11%, respectively, with no influence on the uPA/PAI-1 ratio. Lyophilisation is a safe procedure for the preservation of frozen prostate tissue samples as it permits recovery of the markers without compromising their use for diagnostic purposes.

Circulating uPA as a potential prognostic biomarker for resectable esophageal squamous cell carcinoma

“…uPA, a serine protease with multiple function, acts as risk assessment and a possible treatment target in many cancers, [10,17,18] such as breast cancer, [9,19,20] pancreatic cancer, [21,22] prostate cancer, [23,24] and ovarian cancer. [25–27] In particular, uPA can accelerate tumor metastasis and promote tumor angiogenesis by degrading extracellular matrix (ECM) and basement membranes, such as vimentin and fibronectin, involving in epithelial-mesenchymal transition (EMT).…”