Translational investigations of gastrointestinal malignancies using spheroid cultures.

Abstract

620 Background: Spheroid cultures are now being used to investigate the biology of multiple types of cancer. This technique allows for a cost-effective, efficient and reliable means to culture tissues of interest. Recent investigations have demonstrated that spheroids maintain high mutational concordance with the cancers they are derived. We sought to determine if spheroid techniques could be utilized to perform translational investigations into subtypes of gastrointestinal malignancies. Methods: Transgenic mice carrying conditional mutations in key genes known to have important roles in colorectal cancer (CRC) tumorigenesis and progression were treated with a Cre-expressing adenovirus to initiate tumorigenesis. The mutant genes of interest included Apc, Trp53, KRAS, Pik3ca, and/or BRAF. Biopsies of these cancers were obtained with the murine endoscope and the tissue processed for spheroid culture. In addition, transgenic E6 and E7 mice were treated with DMBA and the resulting anal squamous cell carcinomas were harvested for spheroid culture. Cultured spheroids were imaged to characterize growth rate and changes in architecture. In addition, studies assessing response to therapeutics were performed and correlated with in vivo response. Human operative specimens were also obtained for culturing. Results: Multiple lines of murine CRC spheroids were able to be generated with a greater than 90% efficiency rate. These cultures maintained phenotypic characteristics of the cancers from which they were derived. Bright field imaging pre- and post-treatment was able to be utilized for quantification of treatment response. The median relative change in spheroid diameter was compared across treatment groups and correlated with response in vivo. Heterogeneity in the response of individual spheroids to treatment strategies was detected with this method. Murine squamous cell anal carcinoma was spheroid lines were generated similarly. Human CRC and anal cancers were also generated with high efficiency. Conclusions: Spheroid cultures from CRC and anal cancers can be generated with high efficiency and hold great promise for furthering treatment options for patients with cancer.