Colorectal carcinoma organoid and cancer-associated fibroblasts co-culture system for drug evaluation.

Patient-derived organoids (PDO) have the potential to be used as preclinical cancer models for testing anti-cancer drug efficiency. Cancer-associated fibroblasts (CAFs), which have been closely linked with colorectal carcinoma (CRC) progression and drug resistance, however, are generally not included (or gradually lost during culture) in the PDO models, leading to a major limitation in this cancer model. In this study, we established a new in vitro model with CRC organoids and co-cultured with CAFs and compared it with the organoid-only model. Through testing with anti-cancer drug, we demonstrated a significant difference in drug sensitivity between the two models, and the co-culture model showed higher drug resistance. RNA and whole exome sequencing were performed to reveal gene expression profiles in organoids and organoids co-culture with CAFs to assess interactions between drug sensitivity and gene copy number variation. We found that the expression levels of several pathway protein genes, which are highly expressed in original surgical specimens of colorectal carcinomas, were downregulated in organoids but restored in organoids by co-culturing with CAFs. In summary, the PDO-CAF joint model for CRC can recapitulate a more biomimetic tumor microenvironment and the drug resistance lead by changes in multiple signaling pathways that we discovered; thus, it could be a suitable model for future usage in drug discovery and precision medicine research.