Background

Metastasis and mortality remain high among breast cancer patients with the claudin-low subtype because these tumors are aggressive, chemoresistant, and lack targeted therapies. Our objective was to utilize discovery-based proteomics to identify proteins associated with claudin-low primary and metastatic tumors to gain insight into pathways and mechanisms of tumor progression.

Methods

We used nano-LC-MS/MS proteomics to analyze orthotopic and metastatic tumors from the syngeneic murine T11 tumor model, which displays gene expression profiles mirroring human claudin-low tumors. Galectin-1 identity, expression and spatial distribution were investigated by biochemical and immunochemical methods and MALDI/IMS. RNA seq data from mouse and human tumors in our study and publicly available microarray data were analyzed for differential galectin-1 expression across breast cancer subtypes.

Results

Galectin-1, an N-acetyllactosamine-binding protein, exhibited the highest sequence coverage and high abundance rank order among nano-LC-MS/MS-identified proteins shared by T11 claudin-low tumors but not normal tissue. Label-free quantitation, Western immunoblot and ELISA confirmed galectin-1 identity and significant differential expression. MALDI/IMS spatial mapping and immunohistochemistry detected galectin-1 in T11 metastatic lung foci. Immunohistochemistry of human claudin-low tumors demonstrated intermediate-to-high intensity galectin-1 staining of tumor and stroma. Gene expression analysis of mouse and human tumors found the highest galectin-1 levels in the claudin-low breast cancer subtype.

Conclusions

Proteomics and genomics reveal high expression of galectin-1 protein and RNA in primary and metastatic claudin-low breast cancer.

General significance

This work endorses proteomic approaches in cancer research and supports further investigations of the function and significance of galectin-1 overexpression in claudin-low tumor progression.

中文翻译：

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密蛋白低乳腺癌中肿瘤和转移相关半乳糖凝集素 1 的蛋白质组学鉴定

 背景

密蛋白低亚型乳腺癌患者的转移和死亡率仍然很高，因为这些肿瘤具有侵袭性、化疗耐药性并且缺乏靶向治疗。我们的目标是利用基于发现的蛋白质组学来识别与低密蛋白原发性和转移性肿瘤相关的蛋白质，以深入了解肿瘤进展的途径和机制。

 方法

我们使用纳米 LC-MS/MS 蛋白质组学来分析同基因小鼠 T11 肿瘤模型的原位和转移性肿瘤，该模型显示出反映人类紧密蛋白低肿瘤的基因表达谱。通过生化和免疫化学方法以及 MALDI/IMS 研究 Galectin-1 的身份、表达和空间分布。我们的研究中对来自小鼠和人类肿瘤的 RNA seq 数据以及公开可用的微阵列数据进行了分析，以了解乳腺癌亚型中 galectin-1 表达的差异。

 结果

Galectin-1 是一种N-乙酰基乳糖胺结合蛋白，在 Nano-LC-MS/MS 鉴定的蛋白质中表现出最高的序列覆盖度和高丰度排序，这些蛋白质是 T11 密蛋白低肿瘤而非正常组织共有的。无标记定量、Western 免疫印迹和 ELISA 证实了 galectin-1 的身份和显着的差异表达。 MALDI/IMS 空间绘图和免疫组织化学检测到 T11 转移性肺病灶中的半乳糖凝集素-1。人 Claudin-low 肿瘤的免疫组织化学显示肿瘤和基质具有中等到高强度的半乳糖凝集素 1 染色。对小鼠和人类肿瘤的基因表达分析发现，claudin-low 乳腺癌亚型中的 galectin-1 水平最高。

 结论

蛋白质组学和基因组学揭示了原发性和转移性密蛋白低乳腺癌中半乳糖凝集素 1 蛋白和 RNA 高表达。

 一般意义

这项工作支持癌症研究中的蛋白质组学方法，并支持进一步研究 galectin-1 过表达在 Claudin-low 肿瘤进展中的功能和意义。