Heterogeneity in ERK activity as visualized by in vivo FRET imaging of mammary tumor cells developed in MMTV-Neu mice
Heterogeneity in ERK activity as visualized by in vivo FRET imaging of mammary tumor cells developed in MMTV-Neu mice
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DOI：
10.1038/onc.2014.28
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发表时间：
2015-02-19
期刊：
影响因子：
8
通讯作者：
Matsuda, M.
中科院分区：
文献类型：
--
作者：
Kumagai, Y.;Naoki, H.;Matsuda, M.
人表皮生长因子受体2/Neu在约30%的乳腺癌中过表达，它在很大程度上通过Ras-Raf-MEK-ERK途径传递生长信号。然而，乳腺癌组织中ERK的高活性是否与预后的好坏相关还存在争议，这使得ERK活性在乳腺癌进展中的作用尚未得到解决。为了解决这个问题，我们在小鼠乳腺肿瘤病毒-Neu转基因小鼠的乳腺肿瘤中对ERK活性进行了实时成像，这些转基因小鼠与表达ERK的Forster共振能量转移生物传感器的转基因小鼠杂交。双光子显微镜观察发现乳腺肿瘤细胞间ERK活性存在明显的异质性。每个细胞中的ERK活性水平在几个小时内都是稳定的，这意味着一个强大的机制将ERK活性保持在有限的范围内。通过根据ERK活性对乳腺肿瘤细胞进行分类，我们发现ERKHigh细胞在体外和体内产生肿瘤球体的效率低于ERKlow细胞。与这一发现相一致的是，肿瘤干细胞标志物CD49f、CD24和CD61在ERKHigh细胞中的表达降低。这些观察结果表明，高ERK活性可能抑制乳腺癌干细胞的自我更新。
Human epidermal growth factor receptor2/Neu, which is overexpressed in about 30% of human breast cancers, transduces growth signals in large part via the Ras-Raf-MEK-ERK pathway. Nevertheless, it is a matter of controversy whether high ERK activity in breast cancer tissues correlates with better or worse prognosis, leaving the role of ERK activity in the progression of breast cancers unresolved. To address this issue, we live-imaged ERK activity in mammary tumors developed in mouse mammary tumor virus-Neu transgenic mice, which had been crossed with transgenic mice expressing a Forster resonance energy transfer biosensor for ERK. Observation of the tumor by two-photon microscopy revealed significant heterogeneity in ERK activity among the mammary tumor cells. The level of ERK activity in each cell was stable up to several hours, implying a robust mechanism that maintained the ERK activity within a limited range. By sorting the mammary tumor cells on the basis of their ERK activity, we found that ERKhigh cells less efficiently generated tumorspheres in vitro and tumors in vivo than did ERKlow cells. In agreement with this finding, the expressions of the cancer stem cell markers CD49f, CD24 and CD61 were decreased in ERKhigh cells. These observations suggest that high ERK activity may suppress the self-renewal of mammary cancer stem cells.