Abstract 1245: Standardized 3D spheroid systems facilitate drug screening and biomarker identification with high relevance for cancer drug discovery
Authors: Duez Julien , Fixe Isabelle , Foucher Alexandra , Mennesson Eric , Normand Nadia 
Published: August 2019

Abstract
Whilst patient-derived cancer organoid culture is not yet compatible with high throughput studies, cell-line-derived multicellular spheroids represent an attractive solution, as they offer the possibility to recapitulate the structural and molecular complexity of cancer cell lesions with higher physiological relevance compared to 2D culture systems, thereby generating more predictable results and reducing the expenses attributed to current preclinical attrition rates. As an illustration of the technological services developed by our team, we focused on colorectal cancer, which is one of the most commonly occurring cancer in humans. When stage I and II tumors are curable, metastatic stages of the disease still represent a clinical challenge. Along the last decades, the use of cytotoxic drugs in association with targeted therapies improved the overall survival of patients with metastatic colorectal cancer. However, a large subset of patients continues to be unresponsive, likely due to the high heterogeneity of colorectal cancer lesions. Sustained efforts are then needed to identify and target relevant biomarkers of crucial interest for the development of treatment strategies. CDK8 is a non-mitotic Cyclin-Dependent-Kinase which functions as an oncoprotein in colorectal cancers. Most published drug discovery projects report attractive binding affinity, selectivity and permeability for CDK8 inhibitors amenable to mouse studies. However these compounds generally display weak antiproliferative or cytostatic activity in conventional cell based assays. The signaletic map involving CDK8 in colorectal cancer has mostly been investigated using RNAi mediated suppression studies and kinase dead mutants. Thus, there is an important need to pursue the exploration of the oncogenic role of CDK8 using complementary pharmacological approaches implemented in the most relevant physio-cellular context. Indeed, CDK8 inhibitors in development are mostly evaluated using colorectal cancer cells in standard culture conditions. In this study we aimed to profile the impact of pro-inflammatory conditions on colorectal cancer response to pharmacological CDK8 inhibition, using HT29 cells cultured as monolayers or multicellular spheroids. A panel of targets were analysed through proteomic multiplex microarrays, comparing 2D and 3D cultures. RTqPCR was used to further validate under/over-expressed genes uncovered through the microarray approach. The resulting signature was compared to previously published RNAi-mediated CDK8 expression inhibition results. Cancer cell line-derived multicellular spheroids are compatible with the identification of biomarkers in pro-inflammatory conditions. Such an approach may be further used to adjust current drug discovery methodologies applied to the selection of CDK8 inhibitors, and more generally to antitumoral drugs.
Citation Format: Julien Duez, Isabelle Fixe, Alexandra Foucher, Eric Mennesson, Nadia Normand. Standardized 3D spheroid systems facilitate drug screening and biomarker identification with high relevance for cancer drug discovery [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1245.