Understanding the influence of Mitochondrial DNA haplotypes on breast aging and cancer

不同女性的乳房衰老速度不同。此外，老年妇女往往会产生雌激素。 受体α(ERα)阳性的乳腺癌亚型，尽管激素水平较低。我们的初步数据 迫使我们假设线粒体遗传学改变了乳房的衰老速度，并影响了乳房的亚 乳腺癌的类型。乳腺导管树由管腔激素敏感(HS)、ERα阳性组成 ER-α阴性的细胞以及腔内肺泡(AV)和基底细胞。最近的一项scRNAseq分析 发现在基底和腔内的房室细胞中，线粒体的功能随着年龄的增长而下降，但这种下降 在管腔HS细胞中未观察到。相反，腔内HS细胞似乎上调了未折叠的蛋白质 内质网反应(UPRER)。UPRER与线粒体紧密相连 UPR(UPRmt)。我们的团队已经确定内质网α和线粒体sirtuin-3(sirtuin-3)是 UPRmt.虽然ERα水平不随年龄波动，但在大多数个体中，SIRT3水平随着年龄的增长而下降 年龄。因此，我们的中心假设是，在基底区和基底区观察到的线粒体功能下降 腔内房室细胞的老化可能是由于UPRmt的SIRT3轴的下降所致。然而，在流明中， HS细胞没有观察到这种下降，因为它们通过内质网α轴维持线粒体功能 UPRmt.我们假设，管腔HS细胞在衰老过程中维持线粒体功能的能力， 使他们在转化中存活下来，并解释了老年人对ERα阳性乳腺癌的选择性偏见 女人。此外，我们对年轻和老年女性起源的乳腺肿瘤进行了RNAseq和 已建立的腔HS细胞来源于年轻和老年女性。我们发现ER的标志物？ UPRmt和UPRER轴在衰老的管腔HS细胞中表达上调。这一观察结果 表明ER的转录程序？可能会随着年龄的增长而改变。我们假设 在衰老过程中，ROS的增加和激素的下降改变了ERα的转录程序。 此外，随着年龄的增长，SIRT3的下降速度因个体而异。同样，我们发现， 具有相同核基因组(BL/6)的BL/6NZB和BL/6C57小鼠SIRT3不同 线粒体DNA；(C57或NZB)。因此，这意味着UPRmt的SIRT3轴的下降率与 年龄因mtDNA单倍型而异。最后，我们假设虽然BL/6C57小鼠(低SIRT3)将 在BL/6NZB女性(高SIRT3)中，随着年龄的增长，只发生ERα阳性的乳腺肿瘤。 呃？将观察到阳性的乳腺肿瘤。为了检验这些假设，我们提出了以下目标： 具体目标1：ER-α阳性乳腺组织中UPRMT、UPRER和ER-α转录组的分析 细胞过度老化。特定目标2：对BL/6C57小鼠乳腺的增龄期进行scRNAseq分析 和BL/6NZB小鼠。具体目标3：比较BL/6C57和BL/6NZB的乳腺肿瘤亚型 老鼠过多地衰老。我们建议在绝经前、围绝经期和绝经后以及老年小鼠身上进行这些分析。

The rate of aging of the breast differs between women. Further, older women tend to develop estrogen receptor alpha (ERα) positive breast cancer sub-type, despite lower hormonal levels. Our preliminary data compel us to hypothesize that mitochondrial genetics alters the rate of aging of the breast and impacts the sub- type of breast cancer. The mammary ductal tree is composed of luminal hormone sensitive (HS), ERα positive cells as well as luminal alveolar (AV) and basal cells that are both ERα negative. A recent scRNAseq analysis revealed that in both the basal and luminal AV cells, mitochondrial function declines with age but this decline was not observed in luminal HS cells. Rather, the luminal HS cells seem to up-regulate of the unfolded protein response of the endoplasmic reticulum (UPRER). The UPRER is closely interconnected with the mitochondrial UPR (UPRmt). Our group has identified the ERα and the mitochondrial sirtuin-3 (SIRT3) as key players of the UPRmt. While the level of the ERα does not fluctuate with age, in most individuals, SIRT3 levels decrease with age. Therefore, our central hypothesis is that the decline in mitochondrial function observed in the basal and luminal AV cells over aging may be due to the decline in the SIRT3 axis of the UPRmt. However, in the luminal HS cells this decline is not observed as they maintain mitochondrial function through the ERα axis of the UPRmt. We hypothesize that the ability of luminal HS cells to maintain mitochondrial function through aging, allow them to survive transformation and explains the selective bias toward ERα positive breast cancer in older women. Further, we performed RNAseq on the young and old-females derived mammary tumors and established luminal HS cells derived from both young and aged females. We found that markers of the ER? axis of the UPRmt and UPRER are up-regulated specifically in the aged luminal HS cells. This observation suggests that the transcriptional program of the ER? may be altered by aging. We hypothesize that the increase in ROS and the decline in hormones during aging alter the transcriptional program of the ERα. Further, the rate of decline in SIRT3 with age varies between individuals. Likewise, we found that the levels of SIRT3 differ between the BL/6NZB and BL/6C57 mice which have the same nuclear genome (BL/6), but different mtDNA; (C57 or NZB). Therefore, the implication is that the rate of decline of the SIRT3 axis of the UPRmt with age differs based on mtDNA haplotypes. Lastly, we hypothesize that while BL/6C57 mice (low SIRT3) will develop exclusively ERα positive mammary tumor over aging, in BL/6NZB females (high SIRT3) both basal and ER? positive mammary tumors will be observed. To test these hypotheses, we propose the following aims: Specific aim 1: Analyze of the UPRmt and UPRER and the ERα transcriptome in ERα positive luminal mammary cells over aging. Specific aim 2: Perform scRNAseq analysis of the mammary gland over aging in BL/6C57 and BL/6NZB mice. Specific aim 3: Compare the sub-types of mammary tumors between BL/6C57 and BL/6NZB mice over aging. We propose to do these analyses in pre-, peri- and post-menopausal as well as elderly mice.