Antiestrogens modulate MT1 melatonin receptor expression in breast and ovarian cancer cell lines

Abstract

An interaction between cellular estrogen response and melatonin signaling mediated by G-protein coupled receptors is present in breast cancer cells.

In this study, the effect of antiestrogens on basal and melatonin-modulated expression of MT1 melatonin receptor in breast and ovarian cancer cells was examined.

For this purpose, the effects of the selective estrogen receptor modulator tamoxifen and pure antiestrogen ICI 182,780 on MT1 expression in estrogen receptor (ER) alpha-positive and -negative breast and ovarian cancer cell lines cultured in medium supplemented with 1 nM 17-beta estradiol were assessed by Western blot analysis.

We were able to detect expression of the MT1 receptor in SK-OV-3 and OVCAR-3 cells and report its up-regulation by melatonin in both ovarian cancer cell lines.

MT1 expression was observed to be significantly weaker in ERalpha-positive MCF-7 and OVCAR-3 cells than in ERalpha-negative MDA-MB-231 and SK-OV-3 cells.

Treatment with the pure antiestrogen ICI 182,780 increased MT1 receptor expression in OVCAR-3 ovarian cancer cells, but decreased MT1 expression in MCF-7 breast cancer cells. No effect of ICI 182,780 on MT1 expression was observed in the ERalpha-negative cell lines SK-OV-3 and MDA-MB-231. After treatment with 4-OH tamoxifen, down-regulation of basal MT1 receptor expression in ERalpha-positive MCF-7 cells and inhibition of melatonin-induced up-regulation of MT1 in OVCAR-3 ovarian cancer cells were observed. In contrast, treatment with 4-OH tamoxifen increased the MT1 receptor level in ERalpha-negative SK-OV-3 ovarian cancer cells.

Our findings support the existence of close interaction between estrogen and melatonin signaling. Moreover, our data suggest that melatonin signaling is modulated by antiestrogens in breast and ovarian cancer cells.

 

 

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See also:

- About Melatonin;

- Evaluation of the safety and efficacy of the first-line treatment with somatostatin combined with melatonisn, retinoids, vitamin D3, and low doses of cyclophosphamide in 20 cases of breast cancer: a preliminary report;

- The Di Bella Method (DBM) improved survival, objective response and performance status in a retrospective observational clinical study on 122 cases of breast cancer;

- Complete objective response to biological therapy of plurifocal breast carcinoma.