Endocrine Abstracts

In vitro 3D cell culture systems seem to appropriately reproduce the tumor cell microenvironment, including nutrients-oxygen conditions and cell-cell interactions. These models may better mimic in vivo tumor conditions and more accurately reproduce drug treatments effects. Since most in vitro studies in neuroendocrine tumors (NETs) are performed in 2D culture systems (monolayer), we aimed to compare the monolayer system with a 3D spheroid cell culture system using a human pancreatic neuroendocrine tumor (PNET) model.

Methods: Human BON-1 and QGP-1 PNET cells were used. Total cell number, viability, cell growth, spheroid size, serotonin/chromogranin A (CgA) secretion and somatostatin receptor (sst) and dopamine receptor type 2 (D2R) mRNA expression were assessed in different medium conditions.

Results: Spheroid cultures of BON-1/QGP-1 allowed better cell survival in serum-deprived conditions, compared with monolayer cultures. Total cell number and spheroid size increased in a parallel and time-dependent manner in BON-1 spheroids. In contrast, the increase in total cell number and spheroid size in QGP-1 spheroids were dissociated, probably due to increased cell compactness. In BON-1, Serotonin and CgA release increased in parallel with the increase in spheroid size and total cell number. Hormone release was evaluated in monolayer cultures only after three days because of decreased cell viability after seven days. PNET spheroid growth exhibited time-dependent changes in the mRNA expression of sst subtype and D2R receptors, which was most evident in QGP-1.

Conclusions: These results suggest that spheroids 3D cultures may be a novel method for evaluating cell proliferation and secretion in NET cell models and could help to explain the heterogeneity in NETs. Spheroid cultures grow relatively serum-independent and spheroid size is not an appropriate measure of cell growth in 3D QGP-1 cultures.