A coherence between thyroid dysfunction and
breast cancer incidence exists.
Thyroid hormone metabolites bind to TAAR1 (
trace amine-associated receptor 1) and through that modulate the serotonergic and dopaminergic system.
Catecholamines themselves are synthesized by the
L-dopa decarboxylase (DDC). The aim of our study was to analyze the influence of
catecholamines on the DDC expression in primary
breast cancer patients and the role of DDC concerning overall survival (OS). DDC expression was analyzed by immunohistochemistry. The effect of
epinephrine on the expression of DDC and the Gi-
protein was analyzed on the
protein level via Western blot. A viability assay was performed to test the metabolic cell viability. The overexpression of DDC in the primary
tumor was associated with longer OS (p = 0.03). Stimulation with
epinephrine induced the downregulation of DDC (p = 0.038) and significantly increased viability in T47D cells (p = 0.028). In contrast,
epinephrine induced an upregulation of DDC and decreased the proliferation of MCF7 cells (p = 0.028).
Epinephrine led to an upregulation of Gi
protein expression in MCF7 cells (p = 0.008). DDC is a positive prognostic factor for OS in
breast cancer patients, and it is regulated through
epinephrine differently in MCF7 and T47D. DDC may represent a novel target for the treatment of
breast cancer, especially concerning its interaction with
epinephrine.