Tumor-Draining Lymph Secretome En Route to the Regional Lymph Node in Breast Cancer Metastasis

Abstract

Background

During metastasis, tumor cells metastasize from primary tumors to distant organs via the circulatory and the lymphatic systems. There is a plethora of information about metastasis through the circulatory system, however not much information is available about the tumor cells dissemination through the lymphatic system or the lymphatic microenvironment that aids in this process in breast cancer metastasis.

Purpose

The study designed to examine the tumor-derived secretome in lymph before reaching the draining lymph nodes.

Methods

Using a microsurgical technique, we have collected the lymph in transit from the primary tumor en route to the regional lymph node in animals with metastatic and non-metastatic mammary carcinoma and healthy controls. The lymph samples were subjected to LC-MS/MS analysis, bioinformatics, and pathway analysis.

Results

The metastatic tumor-draining lymph before its entry into the closest regional lymph node contain 26 proteins with >175-folds in abundance compared to lymph from non-metastatic tumor-bearing animals. Among these proteins were biliverdin reductase B, heat shock protein, coagulation factor XIII, lymphocytes cytosol protein 1, and aldose reductase. These proteins were not identified in the lymph from healthy animals. Pathways analysis revealed that cadherin-mediated endocytosis, acute phase response, junction signaling, gap junction, VEGF singling, and PI3K/AKT singling pathways are overrepresented in the lymph from metastatic tumor-bearing compared to the lymph from non-metastatic tumor-bearing animals. Among the significantly up-regulated proteins in the lymph from metastatic tumor-bearing animals were proteins that identified in exosomes include heat shock protein, enolase 1 alpha, S100, and biliverdin reductase B. One of the proteins significantly down-regulated in lymph from animals with metastasis is Kininogen, a known metastasis inhibitor protein.

Conclusion

Proteins and exosomal proteins in lymph draining a metastatic tumor are different from those in lymph draining non-metastatic tumors, and these proteins involved in pathways that regulate tumor cells migration and invasion.

Keywords:

• lymph
• lymphatic vessels
• cancer
• breast
• lymph node
• metastasis
• exosome
• tumor-derived factors

Acknowledgments

The authors thank Dr. Mittal for his continuous support. Also, we thank Dr. Segall from Albert Einstein College of Medicine, the Bronx, NY, for providing the MTln3 and MTC cell lines. The work was supported by DOD concept award # W81XWH‐04‐1‐0747 and NIH/NCI grant # 1R21CA199621.

Ethical Concerns

All experiments involving rats were conducted according to the National Institutes of Health regulation on the care and use of experimental animals. Purdue University Animal Use and Care Committee approved the study.

Author Contributions

All authors made substantial contributions to conception and design, acquisition of data, or analysis and interpretation of data; took part in drafting the article or revising it critically for important intellectual content; gave final approval of the version to be published; and agree to be accountable for all aspects of the work.

Disclosure

Dr Virginia Espina reports personal fees from Avant Diagnostics Investors Group, LLC., outside the submitted work. The authors report no other conflicts of interest in this work.