Flash Talk & Poster Presentation 31st Lorne Cancer Conference 2019

Proteomic profiling of human prostate cancer-associated fibroblasts (CAF) reveals LOXL2-dependent regulation of the tumor microenvironment (#109)

Natalie Lister 1 2 , Mimi Nguyen 2 3 , Brooke Pereira 1 4 , Mitchell Lawrence 1 , Jianmin Wu 5 , Joanna Skhinas 4 , Stewart Ellem 1 6 , Thomas Cox 4 7 , Gail Risbridger 1 2 8 , Renea Taylor 1 , Roger Daly 2 3
  1. Anatomy and Developmental Biology, Monash University, Clayton, VIC, Australia
  2. Cancer Program, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
  3. Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
  4. Cancer Division, The Garvan Institute of Medical Research and The Kinghorn Cancer Centre, Sydney, NSW, Australia
  5. Center for Cancer Bioinformatics , Peking University Cancer Hospital and Institute,, Beijing, China
  6. School of Health and Wellbeing, University of Southern Queensland, Ipswich, Queensland, Australia
  7. Faculty of Medicine, St Vincent’s Clinical School, UNSW Sydney, Sydney , NSW, Australia
  8. Sir Peter MacCallum , Department of Oncology, The University of Melbourne , Parkville, Melbourne, Australia

Introduction: In prostate cancer (PC), cancer-associated fibroblasts (CAF) exhibit contrasting biological properties to non-malignant prostate fibroblasts (NPF) and promote tumorigenesis. Resolving intercellular signaling pathways between CAF and prostate tumor epithelium may offer novel therapeutic targets.

Methods: The proteome and phosphoproteome of four pairs of patient-matched CAF and NPF were characterized to identify discriminating proteomic signatures. Samples were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) with a hyper-reaction monitoring data-independent acquisition (HRM-DIA) workflow.

Results: Proteins that exhibited a significant increase in CAF versus NPF were enriched for the functional categories ‘cell adhesion’ and the ‘extracellular matrix’. STRING analysis of the CAF proteome revealed a prominent interaction hub associated with collagen synthesis, modification, and signaling. It contained multiple collagens, including the fibrillar types COL1A1/2 and COL5A1; the receptor tyrosine kinase discoidin domain-containing receptor 2 (DDR2), a receptor for fibrillar collagens; and lysyl oxidase-like 2 (LOXL2), which promotes collagen crosslinking. Increased expression of DDR2, LOXL2 and pFAK y925 were validated by western blot in the majority of prostate CAF. Clinical interrogation of the TCGA prostate cancer RNAseq dataset (n=492) revealed worsening disease free survival in patients with high level LOXL2 expression. Pharmacological inhibition of CAF-derived LOXL2 with the next generation inhibitor, PXS-S2A, perturbed extracellular matrix (ECM) organization and impaired prostate tumor cell motility.

Conclusion: CAF-derived LOXL2 is an important mediator of intercellular communication within the prostate tumor microenvironment and a potential therapeutic target. Next generation selective inhibitors of LOXL2 show promise for therapeutic treatment of solid tumours.