Endocrine Abstracts

Introduction: Broncho-Pulmonary Neoplasms (BP-NENs) are rare neoplasms arising from neuroendocrine cells of the respiratory epithelium. Since previous studies in our lab have demonstrated the efficacy ofEverolimus, approved for BP-NENs treatment, and Dinaciclib, a Cyclins and CdKs inhibitor, on monolayer system we have investigated if a more complex tumour system could generate a change in drugs effects and cell resistance. Therefore, through the use of 3D culture model, we have cultured BP-NENs tumour cells alone or together with a lung fibroblasts cell line in order to verify the possible role of Tumour Microenvironment in BP-NENs development and drug resistance.

Material and Methods: NCI-H720 and NCI-H727 cell lines were used as BP-NENs model while MRC5 cell line was used as lung fibroblast model. Two lipophilic tracers were used to stain tumour cells and fibroblasts. Everolimus and Dinaciclib were used at 100 nM. Ultra-low attachment 96-well plates with clear round bottomwere used to obtain Spheroids while metabolic activity was assed using MTT assay.

Results: For both cell lines, when tumour cells were co-cultured with MRC5, spheroids appeared more solid and compact. Our results also showed how the spheroids were different: NCI-H727 spheroids were denser in comparison with NCI-H720 and, in addition, when synthetic extracellular matrix was added the latter failed to invade. Tracers analysis also revealed spheroids cellular distribution underlying a tumour cells core with peripheral collocation of fibroblasts. MTT analysis on tumours cells spheroids showed a 20% significant metabolic activity reduction (vs. vehicle DMSO spheroids) for spheroids treated with Dinaciclib while Everolimus treatment didn’t affect basal cell metabolic activity in both cell lines. On the other hand, once in co-culture with MRC5 cells, the cell metabolic reduction observed with Dinaciclib treatment was lost.

Conclusions: Our preliminary results indicate that TME could be important in cell aggregation and spheroids formation and might have a role in drug resistance.