Department of Structural and Cellular Biology, Tulane University School of Medicine, New Orleans, LA 70112, USA.
Breast Cancer Res. 2010;12(6):R107. doi: 10.1186/bcr2794. Epub 2010 Dec 17.
The pineal gland hormone, melatonin, has been shown by numerous studies to inhibit the proliferation of estrogen receptor α (ERα)-positive breast cancer cell lines. Here, we investigated the role of melatonin in the regulation of breast cancer cell invasion.
Three invasive MCF-7 breast cancer cell clones - MCF-7/6, MCF-7/Her2.1, and MCF-7/CXCR4 cells - were employed in these studies. All three cell lines exhibited elevated phosphorylation of the ERK1/2 and p38 mitogen-activated protein kinase (MAPK) as determined by Western blot analysis. The effect of melatonin on the invasive potential of these human breast cancer cells was examined by matrigel invasion chamber assays. The expression and proteinase activity of two matrix metalloproteinases (MMPs), MMP-2 and MMP-9, were analyzed by Western blot analysis and gelatin zymography, respectively.
Melatonin (10-9 M) significantly suppressed the invasive potential of MCF-7/6 and MCF-7/Her2.1 cells as measured by matrigel invasion chamber assays, and significantly repressed the proteinase activity of MMP-2 and MMP-9. In MCF-7/CXCR4 cells, melatonin significantly inhibited stromal-derived factor-1 (SDF-1/CXCL12) induced cell invasion and activity of MMP-9. Elevated expression of the MT1 melatonin receptor further enhanced, while luzindole, an MT1/MT2 antagonist, abrogated melatonin's anti-invasive effect, suggesting that melatonin's effect on invasion is mediated, principally, through the MT1 receptor. Furthermore, melatonin repressed the phosphorylation of p38 MAPK in MCF-7/Her2.1 cells and blocked stromal-derived factor-1 (SDF-1) induced p38 phosphorylation in MCF-7/CXCR4 cells. SB230580, a p38 inhibitor, was able to mimic, while transfection of the cells with a constitutively-active MKK6b construct blocked melatonin's effect on cell invasion, suggesting that the anti-invasive action of melatonin is mediated through the p38 pathway.
Melatonin exerts an inhibitory effect on breast cancer cell invasion through down-regulation of the p38 pathway, and inhibition of MMP-2 and MMP-9 expression and activity.
松果体激素褪黑素已被多项研究表明能抑制雌激素受体α（ERα）阳性乳腺癌细胞系的增殖。在这里，我们研究了褪黑素在调节乳腺癌细胞侵袭中的作用。
本研究采用了三种侵袭性 MCF-7 乳腺癌细胞克隆——MCF-7/6、MCF-7/Her2.1 和 MCF-7/CXCR4 细胞。所有三种细胞系的 ERK1/2 和 p38 丝裂原激活蛋白激酶（MAPK）磷酸化均通过 Western blot 分析确定。通过基质胶侵袭室试验检测褪黑素对这些人乳腺癌细胞侵袭潜能的影响。通过 Western blot 分析和明胶酶谱分析分别分析两种基质金属蛋白酶（MMPs）MMP-2 和 MMP-9 的表达和蛋白酶活性。
褪黑素（10-9 M）显著抑制了 MCF-7/6 和 MCF-7/Her2.1 细胞的侵袭潜能，如基质胶侵袭室试验所示，并显著抑制了 MMP-2 和 MMP-9 的蛋白酶活性。在 MCF-7/CXCR4 细胞中，褪黑素显著抑制了基质衍生因子-1（SDF-1/CXCL12）诱导的细胞侵袭和 MMP-9 的活性。MT1 褪黑素受体的高表达进一步增强，而 MT1/MT2 拮抗剂 luzindole 则消除了褪黑素的抗侵袭作用，表明褪黑素对侵袭的作用主要通过 MT1 受体介导。此外，褪黑素抑制了 MCF-7/Her2.1 细胞中 p38 MAPK 的磷酸化，并阻断了 MCF-7/CXCR4 细胞中基质衍生因子-1（SDF-1）诱导的 p38 磷酸化。p38 抑制剂 SB230580 能够模拟，而转染组成型激活的 MKK6b 构建体可阻断褪黑素对细胞侵袭的作用，表明褪黑素的抗侵袭作用是通过 p38 途径介导的。
褪黑素通过下调 p38 通路、抑制 MMP-2 和 MMP-9 的表达和活性来抑制乳腺癌细胞的侵袭。
