Ovarian cancer is the most lethal of gynaecological diseases with most women diagnosed at an advanced stage when tumour cells have spread into the peritoneum. The tumour-associated stroma promotes cancer progression, yet the precise interactions between cancer cells and their stromal compartments are poorly defined. Cancer-associated proteases like kallikrein-related (KLK) peptidases initiate peritoneal invasion via proteolytic cascades, degradation of extracellular matrix (ECM) proteins and integrin signalling implicated in cell survival and proliferation. We discovered mediators of metastasis by employing a bioengineered 3D approach mimiking the tumour-stroma microenvironment of late stage ovarian cancer.
We established an integrated 3D co-culture model of ovarian cancer and stromal cells using imaging and proliferation analyses. In patients, ovarian cancer cells form multicellular spheroids that accumulate in the tumour fluid and attach to the stromal peritoneal layer. Replicating this interaction, spheroids were grown within biomimetic polyethylene glycol-based hydrogels that comprise ECM features due to incorporation of protease cleavage sites and integrin-binding motifs and layered onto electrospun-fabricated polycaprolactone meshes that allowed attachment of stromal cells representing the peritoneal lining. A whole human genome microarray was conducted to identify genes differentially regulated upon 3D co-culture and KLK expression. Genes were grouped by biological processes using Gene Ontology, and pathways mapped using Ingenuity.
Spheroid growth was enhanced and more genes were differentially expressed upon 3D co-cultures and KLK expression. Regulation of biosynthesis and transcription were altered in cancer cells, while inflammatory and migratory responses changed in stromal cells after 3D co-culture. The prostaglandin-endoperoxide synthase 2 network, including fibroblast growth factor 2, fibroblast growth factor receptor 1 and vascular endothelial growth factor C, was upregulated in cancer cells upon 3D co-culture.
Using this integrated 3D approach, we unraveled pathways that may be crucial in the aetiology of ovarian cancer metastasis and highlight the role of tumour-stromal interactions in disease progression.