众所周知，年轻患者的乳腺癌表现出更具侵袭性的生物学行为，并且与老年患者的相同疾病相比，其预后较差，部分原因是脑转移的发生率增加。这些发现背后的机制解释仍然知之甚少。我们最近报道，与年老小鼠相比，在四种三阴性和管腔 B 型乳腺癌小鼠模型中，年轻小鼠的脑转移明显增加。在这里，我们进行了基于定量质谱的蛋白质组学分析，以确定可能导致乳腺癌脑转移发展中与年龄相关的差异的蛋白质。使用脑向性三阴性乳腺癌的小鼠血源模型（MDA-MB-231BR），我们通过激光显微切割收获了肿瘤转移亚群、肿瘤邻近的转移微环境和未受累的脑组织，然后使用高通量定量蛋白质组分析。分辨率质谱法来表征可能导致年龄依赖性脑转移率的差异丰富蛋白质。通路分析揭示了信号通路的显着改变，特别是在转移微环境中，调节肿瘤发生、代谢过程、炎症和神经元信号传导。相对于年老宿主，从年轻小鼠收获的所有激光显微切割 (LMD) 富集区室中，腱蛋白 C (TNC) 显着升高，这一点通过全脑裂解物的免疫印迹分析得到验证和证实。其他体外研究（包括迁移和伤口愈合测定）证明 TNC 是肿瘤细胞迁移的正调节因子。这些结果提供了关于微环境因素（包括 TNC）的重要新见解，作为导致年轻乳腺癌患者中观察到的脑癌转移表型增加的机制。© 2023。这是美国政府的作品，在美国不受版权保护；可能适用外国版权保护。

Breast cancer in young patients is known to exhibit more aggressive biological behavior and is associated with a less favorable prognosis than the same disease in older patients, owing in part to an increased incidence of brain metastases. The mechanistic explanations behind these findings remain poorly understood. We recently reported that young mice, in comparison to older mice, developed significantly greater brain metastases in four mouse models of triple-negative and luminal B breast cancer. Here we have performed a quantitative mass spectrometry-based proteomic analysis to identify proteins potentially contributing to age-related disparities in the development of breast cancer brain metastases. Using a mouse hematogenous model of brain-tropic triple-negative breast cancer (MDA-MB-231BR), we harvested subpopulations of tumor metastases, the tumor-adjacent metastatic microenvironment, and uninvolved brain tissues via laser microdissection followed by quantitative proteomic analysis using high resolution mass spectrometry to characterize differentially abundant proteins potentially contributing to age-dependent rates of brain metastasis. Pathway analysis revealed significant alterations in signaling pathways, particularly in the metastatic microenvironment, modulating tumorigenesis, metabolic processes, inflammation, and neuronal signaling. Tenascin C (TNC) was significantly elevated in all laser microdissection (LMD) enriched compartments harvested from young mice relative to older hosts, which was validated and confirmed by immunoblot analysis of whole brain lysates. Additional in vitro studies including migration and wound-healing assays demonstrated TNC as a positive regulator of tumor cell migration. These results provide important new insights regarding microenvironmental factors, including TNC, as mechanisms contributing to the increased brain cancer metastatic phenotype observed in young breast cancer patients.© 2023. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.