Abstract

3D Multicellular Tumor Spheroids to Study Intra-Tumor Heterogeneity and Cell Communication In Colorectal Cancer

Wenjin Xiao, Postdoctoral Fellow, UMRS1138, Centre de Recherche des Cordeliers, Université Paris Cité

The major underlying cause for colorectal cancer (CRC) high mortality rate relies on its drug resistance, to which intra-tumor heterogeneity (ITH) contributes extensively. However, the impact of ITH on CRC evolution and drug resistance remains underexplored. Multicellular tumour spheroids (MCTSs) have been highlighted as pertinent in vitro cancer models, since they are able to more accurately mimic both the 3D structure of malignant tissue and the cancer microenvironment compared to the traditional 2D format. Here, we describe a 3D spheroid model that could mimick the ITH of CRC to study the effect of heterogeneous inter-cellular communication. These MCTSs were composed of CRC cell lines with distinct molecular subtypes, which were capable to grow into a physiological relevance size in a 4-day culture. We observed the specific spatial distribution of each cell population within the spheroids, in line with the observations in tumours. Interestingly, co-cultures did not alter the cell growth in the MCTSs, but significantly sustained the cellular survival in response to a front-line chemotherapeutic drug, 5-Fluorouracil (5-FU). This phenomenon can be supported by the cell secretome, which showed not only remarkable protective effect against 5-FU treatments, but also sustained cell migration and invasion capacity, suggesting that direct cell-cell interaction is not key in this cell communication. Overall, our MCTS model shows a possibility to mimic ITH and to study the therapy-induced cell interplay in vitro, which could potentially stimulate patient CRC progression and in this manner reduce chemotherapy efficacy.