Department of Chemistry, University of Massachusetts , Amherst , MA , USA.
Department of Biochemistry and Molecular Biology, University of Massachusetts , Amherst , MA , USA.
Cell Cycle. 2019 Oct;18(19):2447-2453. doi: 10.1080/15384101.2019.1648957. Epub 2019 Aug 11.
Epidemiological studies have shown that humans with altered circadian rhythms have higher cancer incidence, with breast cancer being one of the most cited examples. To uncover how circadian disruptions may be correlated with breast cancer and its development, prior studies have assessed the expression of and core clock genes via RT-qPCR and western blot analyses. These and our own low-resolution data show that and expression are suppressed and arrhythmic. We hypothesized that oscillations persist in breast cancer cells, but due to limitations of protocols utilized, cannot be observed. This is especially true where dynamic changes may be subtle. In the present work, we generated luciferase reporter cell lines representing high- and low-grade breast cancers to assess circadian rhythms. We tracked signals for and to determine whether and to what extent oscillations exist and provide initial correlations of circadian rhythm alterations with breast cancer aggression. In contrast to previous studies, where no oscillations were apparent in any breast cancer cell line, our luminometry data reveal that circadian oscillations of and in fact exist in the low-grade, luminal A MCF7 cells but are not present in high-grade, basal MDA-MB-231 cells. To our knowledge, this is the first evidence of core circadian clock oscillations in breast cancer cells. This work also suggests that circadian rhythms are further disrupted in more aggressive/high tumor grades of breast cancer, and that use of real time luminometry to study additional representatives of breast and other cancer subtypes is merited.
流行病学研究表明，生物钟节律改变的人癌症发病率更高，乳腺癌就是其中被引用最多的例子之一。为了揭示生物钟紊乱如何与乳腺癌及其发展相关，之前的研究通过 RT-qPCR 和 Western blot 分析评估了 和 核心时钟基因的表达。这些和我们自己的低分辨率数据表明， 和 的表达受到抑制且呈非节律性。我们假设乳腺癌细胞中存在波动，但由于所用方案的局限性，无法观察到。在动态变化可能很细微的情况下尤其如此。在本工作中，我们生成了代表高低级别乳腺癌的荧光素酶报告细胞系，以评估昼夜节律。我们跟踪 和 的信号，以确定是否存在波动以及存在的程度，并初步将昼夜节律改变与乳腺癌侵袭性相关联。与之前在任何乳腺癌细胞系中都没有明显波动的研究相反，我们的发光计数据显示， 和 的昼夜波动实际上存在于低级别、管腔 A 型 MCF7 细胞中，但不存在于高级别、基底型 MDA-MB-231 细胞中。据我们所知，这是乳腺癌细胞中核心生物钟振荡的第一个证据。这项工作还表明，昼夜节律在更具侵袭性/高肿瘤分级的乳腺癌中进一步受到破坏，并且使用实时发光计研究乳腺癌和其他癌症亚型的更多代表是值得的。
