Abstract 4280: Differential influence of naïve & tumour-conditioned mesenchymal stem cells on the growth of human epithelial cells in in vitro monolayer co-cultures & 3D hollow fibre systems

Abstract

Abstract Background: Tumour cell behaviour is altered by the non-neoplastic portion of the stroma composed of fibroblasts, mesenchymal stem cells (MSC), pericytes, endothelial and inflammatory cells actively intertwined with the tumour parenchyma. Epithelial to mesenchymal transition (EMT) is a key phenotypic change involved in carcinoma progression, resulting in profound phenotypic changes to malignant cells e.g. loss of cell-cell adhesion, loss of cell polarity and acquisition of migratory and invasive properties. Human MSC can give rise to endothelial-like or pericyte-like cells, and are also capable of differentiating into carcinoma associated fibroblasts (CAFs) when exposed to soluble factors produced by tumour cells, which support the malignant epithelial cells resulting in overall enhanced tumour growth and survival in vitro and in vivo. EMT is common within primary tumours and may be further promoted by associated CAFs. Objectives: The objectives of our current research are to recapitulate the human tumour micro-environment within the hollow fibre model (HF) and apply a real-time bio-imaging component to enable the non-invasive analysis of biological parameters associated with tumour progression. Results: Using tumour cells stably expressing a bioluminescent reporter gene, we have investigated tumour growth in the presence and absence of naive (MSC) and tumour-conditioned (tcMSC) human mesenchymal stem cells both within in vitro cell cultures and the HF model. Real-time imaging of bioluminescent tumour cells demonstrated that these cells can actively proliferate within the HFs; and the presence of MSC or tcMSC significantly enhances tumour growth compared with tumour cells alone. Immuno-staining analysis revealed that a stromal network is established around the periphery of the fibre and that with prolonged culture, MSCs acquire a ‘myofibroblastic’ phenotype (elevated expression of αSMA and FSP1) resulting in growth promoting effects similar to CAFs. Here, we also demonstrate downregulation of E-Cadherin – a hallmark of EMT- and upregulation of genes of the EMT trascriptome, in both direct and indirect co-cultures.Conclusions: Here we provide experimental evidence that naive MSC or tcMSC may provide a tumour cell-protective setting and alter tumour behaviour both in vitro and in the hollow fibre model. Real-time PCR data obtained from direct and indirect co-cultures also provide an insight in the co-evolution of the carcinoma and surrounding stroma with the overall microenvironment. Finally, this recapitulation of the human tumour micro-environment provides a relevant model by which to identify and characterise novel anti-cancer compounds. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4280. doi:10.1158/1538-7445.AM2011-4280