Introduction: Pheochromocytomas and paragangliomas (PPGLs) are neuroendocrine tumours originating from chromaffin tissue of the adrenal medulla or from extra-adrenal sympathetic and parasympathetic paraganglia. Approximately 40% of all cases are caused by a germline mutation. PPGLs due to mutations in the β-subunit of the succinate dehydrogenase (SDHB) have the highest metastatic rate, for which effective systemic therapy is lacking. To better understand the pathophysiology and for identification and testing of therapeutic targets, a proper cell model is warranted. We therefore analysed the potential of a temperature-inducible-differentiating murine adrenal medullar cell line, tsAM5NE cells.
Methods: tsAM5NE cells are derived from the adrenal medulla of mice transgenic for the thermo-sensitive T-antigen, which proliferate at 33oC and, due to inactivation of the T-antigen, differentiate to adrenal medulla cells when grown at 39oC. Catecholamine storage was determined of cells stimulated with and without the glucocorticoid hormone dexamethasone for three days, grown at 33oC and 39oC.
Results: <5% of the tsAM5NE cells survived 3 days at 39oC, whereas all cells survived 3 days at 33oC. When grown at 33oC, noradrenaline and adrenaline content was 246.8±6.0 nmol/109 cells and 0.1±0.04 nmol/109 cells, respectively. Adrenaline (7.5±0.5 nmol/109 cells), but not the noradrenalin (210.3±10.0 nmol/109 cells), content was markedly increased following dexamethasone stimulation. At 39oC, noradrenalin and adrenalin levels were 49.25±3.9 and <0.9 nmol/109 cells, respectively, which increased to 137.1±24.34 and 89.9±15.4 nmol/109 cells with dexamethasone, respectively. The cells showed an increased adrenaline/noradrenaline ratio upon dexamethasone stimulation when grown at 39oC (0.656) compared to 33oC (0.036) indicating a more differentiated phenotype when growing at 39 oC.
Conclusion: tsAM5NE cells closely replicate the dexamethasone sensitive secretory phenotype of chromaffin cells and hold promise for the development of a model system for SDHB deficient PPGL.