Circulating tumor cells (CTCs) are cells that have detached from the primary tumor and entered the bloodstream with the potential to seed metastatic tumors in distal sites. High CTC numbers correlate with aggressive disease, increased metastasis, and decreased time to relapse. It has also been shown that cancer stem cells (CSCs) represent a proportion of the CTCs present in patients. Given that CSCs are resistant to chemotherapy and are responsible for tumor initiation, it is posited that the CSCs are the seeds of metastasis. However, direct evidence for this hypothesis is limited because there are few methods for culturing and studying these rare cells. We are using a 3D culture chamber system (RealBio D4™) to establish long-term cultures of human-derived breast and pancreatic tumors. We observed that the system's 3D matrix supported culture development and incorporation of tissue organization and microenvironment. Further, the chamber design allowed CTCs generated within the cultures to migrate out of the cell mass into the circulating nutrient medium where they were collected for characterization. The isolated CTCs displayed CSC properties via CellSearch® (CD44+,CD24-; CD44+,CD24+ for breast and pancreas respectively). In addition, these isolated CTCs displayed tumor-initiating capacity when implanted into mice. Future studies will compare CTCs isolated from 3D culture with cells from tumors, blood, and tissue grown on scaffold through RT-PCR, histology, and gene expression assays.

Citation Format: Marina C. Cabrera, Elaine Hurt, Xiaoru Chen, Shi Xiaoqing, Haifeng Bao. Circulating tumor cells from in vitro 3D culture systems have tumor-initiating capacity in vivo. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1717.