Curcumin Sensitizes Prolactinoma Cells to Bromocriptine by Activating the ERK/EGR1 and Inhibiting the AKT/GSK-3β Signaling Pathway In Vitro and In Vivo.

Although bromocriptine (BRC) as first-line drug is recommended for treating patients with prolactinoma, a minority of patients with prolactinoma are resistance to BRC. Moreover, our previous study showed the difference in drug sensitivity in BRC-treated rat prolactinoma cells, MMQ cells are more resistant to BRC, and GH3 cells are more sensitive to BRC. Curcumin (Cur) has been shown to inhibit proliferation of prolactinoma cell lines. The aim of this study is to further investigate whether Cur could enhance the growth-inhibitory effect of BRC resistance on prolactinoma cell lines and its possible mechanism. CCK-8 kit was used to test cell growth. Cell cycle analysis and apoptosis were performed by flow cytometry. Electron microscopy was used to test autophagosome. The mRNA expression profiles were analyzed using the Affymetrix Gene-Chip array. Western blot was used to test protein expression. Our data showed that Cur enhanced the growth-inhibitory effect of BRC on GH3 and MMQ cell proliferation. BRC and Cur both induced cell apoptosis, and Cur could significantly increase the apoptosis of BRC on pituitary adenoma cells through the ERK/EGR1 signaling pathway. Moreover, Cur could enhance the autophagic cell death (ACD) of BRC on tumor cells by inhibiting the AKT/GSK-3β signaling pathway. The same results were confirmed invivo study. Taken together, Cur sensitizes rat prolactinoma cells to BRC by activating the ERK/EGR1 and inhibiting the AKT/GSK-3β signaling pathway.