Lipoxygenase mediates invasion of intrametastatic lymphatic vessels and propagates lymph node metastasis of human mammary carcinoma xenografts in mouse
Dontscho Kerjaschki, … , Dieter Steinhilber, Georg Krupitza
Dontscho Kerjaschki, … , Dieter Steinhilber, Georg Krupitza
Published April 11, 2011
Citation Information: J Clin Invest. 2011;121(5):2000-2012. https://doi.org/10.1172/JCI44751.
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Research Article Oncology

Lipoxygenase mediates invasion of intrametastatic lymphatic vessels and propagates lymph node metastasis of human mammary carcinoma xenografts in mouse

Abstract

In individuals with mammary carcinoma, the most relevant prognostic predictor of distant organ metastasis and clinical outcome is the status of axillary lymph node metastasis. Metastases form initially in axillary sentinel lymph nodes and progress via connecting lymphatic vessels into postsentinel lymph nodes. However, the mechanisms of consecutive lymph node colonization are unknown. Through the analysis of human mammary carcinomas and their matching axillary lymph nodes, we show here that intrametastatic lymphatic vessels and bulk tumor cell invasion into these vessels highly correlate with formation of postsentinel metastasis. In an in vitro model of tumor bulk invasion, human mammary carcinoma cells caused circular defects in lymphatic endothelial monolayers. These circular defects were highly reminiscent of defects of the lymphovascular walls at sites of tumor invasion in vivo and were primarily generated by the tumor-derived arachidonic acid metabolite 12S-HETE following 15-lipoxygenase-1 (ALOX15) catalysis. Accordingly, pharmacological inhibition and shRNA knockdown of ALOX15 each repressed formation of circular defects in vitro. Importantly, ALOX15 knockdown antagonized formation of lymph node metastasis in xenografted tumors. Furthermore, expression of lipoxygenase in human sentinel lymph node metastases correlated inversely with metastasis-free survival. These results provide evidence that lipoxygenase serves as a mediator of tumor cell invasion into lymphatic vessels and formation of lymph node metastasis in ductal mammary carcinomas.

Authors

Dontscho Kerjaschki, Zsuzsanna Bago-Horvath, Margaretha Rudas, Veronika Sexl, Christine Schneckenleithner, Susanne Wolbank, Gregor Bartel, Sigurd Krieger, Romana Kalt, Brigitte Hantusch, Thomas Keller, Katalin Nagy-Bojarszky, Nicole Huttary, Ingrid Raab, Karin Lackner, Katharina Krautgasser, Helga Schachner, Klaus Kaserer, Sandra Rezar, Sybille Madlener, Caroline Vonach, Agnes Davidovits, Hitonari Nosaka, Monika Hämmerle, Katharina Viola, Helmut Dolznig, Martin Schreiber, Alexander Nader, Wolfgang Mikulits, Michael Gnant, Satoshi Hirakawa, Michael Detmar, Kari Alitalo, Sebastian Nijman, Felix Offner, Thorsten J. Maier, Dieter Steinhilber, Georg Krupitza

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Figure 1

Intrametastatic lymphangiogenesis and tumor cell invasion into lymphatic vessels in sentinel lymph nodes of human ductal mammary carcinomas with postsentinel metastasis.

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Intrametastatic lymphangiogenesis and tumor cell invasion into lymphatic...
Lymphatic endothelial cells are localized by double labeling for podoplanin (red) and PROX1 (black) in A–C and E. (A) In a primary ductal carcinoma, lymphatic vessels are localized in the peritumoral stroma (arrow). The tumor border is marked by a green line. (B) Sentinel lymph node metastasis of the same carcinoma as in part A, with dense intrametastatic lymphatic vascularization. LN, residual lymph node parenchyma. Insert, FLT4 (red) in an intrametastatic lymphatic vessel (PROX1, black). (C) High-power view of an intrametastatic lymphatic vessel with podoplanin+ lymphatic endothelial cells and PROX1-expressing nuclei (arrows). The vessel contains a tumor embolus and is surrounded by mononuclear inflammatory or tumor cells. (D) Keratin+ tumor cell emboli (brown) within intrametastatic lymphatic vessels with podoplanin+ endothelial cells (red). (E) Large tumor embolus completely filling the lumen of an intrametastatic lymphatic vessel. (F) Aggregate of keratin+ carcinoma cells disrupts an intrametastatic lymphatic vessel that is outlined by a single line of PROX1+ nuclei (red). The margins of the vessel’s rupture are indicated by green arrows. (G and H) Embolic tumor cell clusters (black arrows) within a branched intrametastatic lymphatic vessel, and a focal disruption of the lymphatic vascular wall by a bulk of aggregated tumor cells (green arrow). The lymphatic vessel’s walls are composed of a single endothelial layer. Scale bars: 100 μm; 25 μm (insert).