Serotonin Regulates β-Casein Expression via 5-HT7 Receptors in Human Mammary Epithelial MCF-12A Cells

• Published in: Biological and Pharmaceutical Bulletin Vol. 38; no. 3; pp. 448 - 453
• Main Authors: Takeshi Chibaa, Soichiro Kimurab, Katsuo Takahashia, Yasunori Morimotob, Tomoji Maedac, Atsushi Sanbed, Hideo Uedab, Kenzo Kudoa
• Format: Journal Article
• Language: Japanese
• Published: Pharmaceutical Society of Japan 01.03.2015
• ISSN: 0918-6158

We previously reported that serotonin (5-hydroxytryptamine; 5-HT) suppresses β-casein expression, a differentiation marker in mammary epithelial cells, via inhibition of the signal transducer and activator of transcription 5 (STAT5) phosphorylation in the human mammary epithelial cell line, MCF-12A. In this study, we investigated the expression pattern of the different 5-HT receptor subtypes in MCF-12A cells, and identified the receptors involved in 5-HT-mediated suppression of β-casein protein expression. β-Casein mRNA expression was inhibited by 30μM 5-HT in a time-dependent manner. Treatment with 30μM 5-HT for 72h decreased β-casein protein levels and STAT5 phosphorylation (pSTAT5). The cells expressed four 5-HT receptors subtypes (5-HTR1D, 2B, 3A, and 7) at the mRNA and protein level, and their expression was elevated by prolactin (PRL) treatment. Additionally, the mRNA levels of 5-HTR1D and 5-HTR7 were significantly higher than the other 5-HT receptors in the cells. Tryptophan hydroxylase 1 mRNA was detectable in the cells in the absence of PRL, and PRL treatment significantly increased its expression. β-Casein and pSTAT5/STAT5 levels in the cells co-treated with 5-HT and a selective 5-HTR1D inhibitor, BRL15572, were equal to those observed in cells treated with 5-HT alone. However, in the cells co-treated with 5-HT and a selective 5-HTR7 inhibitor, SB269970, β-casein and pSTAT5/STAT5 levels increased in a SB269970 concentration-dependent manner. In conclusion, we showed that 5-HT regulates β-casein expression via 5-HTR7 in MCF-12A human mammary epithelial cells.