Molecular deficiency (ies) in MT1 melatonin signaling pathway underlies the melatonin-unresponsive phenotype in MDA-MB-231 human breast cancer cells

Authors

  • Lulu Mao,

    Corresponding author
    1. Department of Structural and Cellular Biology, Tulane University School of Medicine, New Orleans, LA, USA
    2. Tulane Cancer Center and Louisiana Cancer Research Consortium, New Orleans, LA, USA
    • Address reprint requests to Lulu Mao, Department of Structural and Cellular Biology, Tulane University School of Medicine, 1430 Tulane Avenue, SL-49, New Orleans, LA 70112, USA.

      E-mail: lmao1@tulane.edu

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  • Lin Yuan,

    1. Department of Structural and Cellular Biology, Tulane University School of Medicine, New Orleans, LA, USA
    2. Tulane Cancer Center and Louisiana Cancer Research Consortium, New Orleans, LA, USA
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  • Shulin Xiang,

    1. Department of Structural and Cellular Biology, Tulane University School of Medicine, New Orleans, LA, USA
    2. Tulane Cancer Center and Louisiana Cancer Research Consortium, New Orleans, LA, USA
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  • Samantha B. Zeringue,

    1. Department of Surgery, Tulane University School of Medicine, New Orleans, LA, USA
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  • Robert T. Dauchy,

    1. Department of Structural and Cellular Biology, Tulane University School of Medicine, New Orleans, LA, USA
    2. Tulane Cancer Center and Louisiana Cancer Research Consortium, New Orleans, LA, USA
    3. Laboratory of Chrono-Neuroendocrine Oncology, Tulane University School of Medicine, New Orleans, LA, USA
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  • David E. Blask,

    1. Department of Structural and Cellular Biology, Tulane University School of Medicine, New Orleans, LA, USA
    2. Tulane Cancer Center and Louisiana Cancer Research Consortium, New Orleans, LA, USA
    3. Laboratory of Chrono-Neuroendocrine Oncology, Tulane University School of Medicine, New Orleans, LA, USA
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  • Adam Hauch,

    1. Department of Surgery, Tulane University School of Medicine, New Orleans, LA, USA
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  • Steven M. Hill

    1. Department of Structural and Cellular Biology, Tulane University School of Medicine, New Orleans, LA, USA
    2. Tulane Cancer Center and Louisiana Cancer Research Consortium, New Orleans, LA, USA
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Abstract

Melatonin has been shown repeatedly to inhibit the growth of human breast tumor cells in vitro and in vivo. Its antiproliferative effects have been well studied in MCF-7 human breast cancer cells and several other estrogen receptor α (ERα)-positive human breast cancer cell lines. However, the MDA-MB-231 breast cancer cell line, an ERα-negative cell line widely used in breast cancer research, has been shown to be unresponsive to melatonin's growth-suppressive effect in vitro. Here, we examined the effect of melatonin on the cell proliferation of several ERα-negative breast cancer cell lines including MDA-MB-231, BT-20, and SK-BR-3 cells. Although the MT1 G-protein-coupled receptor is expressed in all three cell lines, melatonin significantly suppressed the proliferation of SK-BR-3 cells without having any significant effect on the growth of MDA-MB-231 and BT-20 cells. We confirmed that the MT1-associated Gα proteins are expressed in MDA-MB-231 cells. Further studies demonstrated that the melatonin unresponsiveness in MDA-MB-231 cells may be caused by aberrant signaling downstream of the Gαi proteins, resulting in differential regulation of ERK1/2 activity.

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