Development of a Thyroid Cancer to Lung Metastasis-on-a-Chip Model

Background: Study of the metastatic cascade in differentiated non-medullary thyroid cancer (NMTC) is hampered by the relative lack of preclinical models that metastasize from primary tumors to other organs. We previously identified regulator of calcineurin 1 isoform 4 (RCAN1.4) as a suppressor of NMTC cell growth, invasion, and metastasis using in vitro systems and tail vein injections in immunocompromised mice. We then reported a microfluidic device mimicking the mouse tail vein injection where cancer cells were allowed to flow directly to lung organoid constructs. We now report the development of a full primary tumor to lung metastasis-on-a-chip (MOC) model for TC. Methods: Resin molds for primary and secondary sites connected by a channel were 3D printed and filled with polydimethylsiloxane to create a molded silicone elastomer. The primary site was seeded with an organoid composed of a hyaluronic acid and collagen-based hydrogel into which FTC236 and HTh74 NMTC cells with and without knockdown of RCAN1.4 were engrafted. The secondary site consisted of a hydrogel organoid into which bronchial epithelial cells and lung fibroblasts were seeded. Culture media was circulated and movement of NMTC cells to the secondary site was assessed. Results: Both cell lines that expressed RCAN 1.4 metastasized to the secondary lung site. RCAN1.4-reduced FTC236 cells had increased metastatic behavior vs controls while HTh74 was less affected by RCAN1.4 loss, similar to prior studies. To determine if the MOC could be used for incorporation of immune components and therapeutic modeling, NK-92 cells were added and were shown to be reduce metastases for both cell lines in the presence or absence of RCAN1.4. Analysis of MOC circulating fluid revealed elevated levels of granzyme B, consistent with NK-92 cell activation. Cytokine profiling identified elevated probable NMTC and NK-92-derived factors. Conclusions: These results indicate that NMTC metastatic behavior can be modeled using a novel MOC system for mechanistic and preclinical therapeutic studies.