The molecular consequences of androgen activity in the human breast (RNA-seq data). The molecular consequences of androgen activity in the human breast (RNA-seq data)

The mammary gland is a hormone responsive organ and has been extensively studied under the influences of estrogen and progesterone. However, the molecular implications of androgen exposure in the normal breast remain elusive and unexplored, partially due to a lack of relevant tissue to study the functional consequences of androgen action. Transgender men are born female but identify as male, and many choose to undergo gender-affirming androgen therapy, which elicits wide-ranging masculinizing effects that help align their physical characteristics and gender identity. Here we perform single cell resolution profiling of androgen treated breast tissue from transgender men at the transcriptome, chromatin, and spatial level to elucidate the regulatory action of androgen. We show male-biased androgen receptor gene targets are specifically upregulated in androgen receptor expressing cell types, and that other sex-relevant changes are also initiated in cells lacking androgen receptor expression, through paracrine signaling cascades. We observe a functionally and structurally altered epithelium, shifts in immune populations and directed reduction of capillary vasculature. Finally, we discover evidence of the metabolic impact of androgen and demonstrate how the treatment induces fat loss by specifically targeting adipocyte function. This work provides a comprehensive and mechanistic characterization of the mammary tissue responses to androgen activity at single-cell resolution. Overall design: single nuclei RNA and ATAC sequencing was used to interrogate molecular responses in breast tissue cells of transgender men and cis-gender females.

乳腺是一种激素响应性器官，此前已针对雌激素（estrogen）与孕酮（progesterone）的调控作用开展了大量研究。然而，正常乳腺组织中雄激素暴露的分子层面效应仍不明晰且未得到充分探索，部分原因是缺乏可用于研究雄激素作用功能后果的相关组织。跨性别男性（transgender men）出生时性别为女性，但自我认同为男性，其中多数会接受性别确认雄激素治疗（gender-affirming androgen therapy），该疗法可诱发广泛的男性化效应，助力其身体特征与性别身份相匹配。本研究针对跨性别男性接受雄激素治疗后的乳腺组织，从转录组（transcriptome）、染色质（chromatin）及空间维度开展单细胞分辨率组学分析，以阐明雄激素的调控作用机制。研究发现，雄激素受体（androgen receptor）表达细胞类型中，雄性偏向的雄激素受体靶基因呈现特异性上调；而在不表达雄激素受体的细胞中，其他性别相关的变化也可通过旁分泌信号级联反应（paracrine signaling cascades）被激活。我们还观察到上皮组织在功能与结构上均发生改变，免疫细胞群出现动态迁移，毛细血管网络呈现定向缩减。最后，本研究发现了雄激素产生代谢影响的相关证据，并阐明了该治疗如何通过特异性靶向脂肪细胞功能来诱导脂肪减少。本研究实现了单细胞分辨率下乳腺组织对雄激素活性响应的全面且机制性表征。实验整体设计：本研究采用单细胞核RNA测序（single nuclei RNA sequencing）与转座酶可及性染色质测序（ATAC sequencing）技术，对跨性别男性与顺性别女性（cis-gender females）的乳腺组织细胞的分子响应进行解析。