Poster Presentation 30th Lorne Cancer Conference 2018

Bioengineered human prostate microtissues reveal key role of mast cell-derived tryptase in potentiating CAF-induced malignancy in vitro (#241)

Brooke A Pereira 1 , Natalie L Lister 1 , Mitchell G Lawrence 1 , Elena M De-Juan-Pardo 2 3 , Stuart J Ellem 1 4 , Dietmar W Hutmacher 2 3 , Gail P Risbridger 1 5
  1. Department of Anatomy and Developmental Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
  2. Centre In Regenerative Medicine, Institute of Health & Biomedical Innovation, Queensland University of Technology, Kelvin Grove, QLD, Australia
  3. ARC Centre In Additive Biomanufacturing, Queensland University of Technology, Kelvin Grove, QLD, Australia
  4. Department of Physiology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
  5. Research Division, Peter MacCallum Cancer Centre, Victorian Comprehensive Cancer Centre, Parkville, Victoria, Australia

The tumour microenvironment (TME) plays a fundamental role in prostate carcinogenesis. Classical tumour recombination experiments have shown that cancer-associated stroma directs tumour formation in benign epithelia. Despite this, stromal components are often overlooked in human prostate cancer (PCa) models. Currently, there are no adequate models of human PCa which examine the combined contribution of cancer-associated fibroblasts (CAF), their aberrant extracellular matrix (ECM) and key resident immune population, mast cells (MC). Mast cells significantly expand in the prostatic TME with increasing tumour grade and are also pro-tumourigenic in other tissues. Here we describe a 3D bioengineered TME microtissue in vitro model which interrogates the interaction and contribution of these components in early prostate carcinogenesis.

Melt-electrospun scaffolds were formatted from poly(ε-caprolactone). Patient-derived primary CAFs or non-malignant prostatic fibroblasts (NPFs) were incorporated into the scaffolds, forming a 3D microtissue. Once confluent, tagged benign epithelial cells (BPH-1 or RWPE-1) were co-cultured on the microtissues ± MC (HMC-1 or LAD2), MC-conditioned media (CM) or recombinant tryptase. Subsequently, tumourigenicity was assessed by analysing the 3D morphological transformation of epithelial cells. Additionally, live cell migration assays were performed to further quantify invasive potential.

Our data show that CAF and NPF proliferate and each deposit distinct ECM to form a 3D stromal network within the scaffolds. CAF ECM is desmoplastic and significantly linearised compared to NPF. CAF, but not NPF, induce an invasive morphology in the benign epithelium. MCs cooperate with CAFs, potentiating CAF-induced tumourigenic effects. These effects are mediated by MC secreted factors, specifically tryptase (a serine protease). Our data indicate that MC-derived tryptase likely acts by remodelling the native aberrant ECM deposited by CAFs, conferring tumourigenicity on the benign epithelia.

Overall, this model demonstrates the cascade of interactions between CAFs, ECM and MCs, mediated by tryptase, to drive early epithelial transformation in the human prostate. Our data highlight tryptase as a key mediator of these effects, which may be a novel therapeutic target to slow carcinogenesis.