A critical role for lymphatic endothelial heparan sulfate in lymph node metastasis.

BACKGROUND: Lymph node metastasis constitutes a key event in tumor progression. The molecular control of this process is poorly understood. Heparan sulfate is a linear polysaccharide consisting of unique sulfate-modified disaccharide repeats that allow the glycan to bind a variety of proteins, including chemokines. While some chemokines may drive lymphatic trafficking of tumor cells, the functional and genetic importance of heparan sulfate as a possible mediator of chemokine actions in lymphatic metastasis has not been reported. RESULTS: We applied a loss-of-function genetic approach employing lymphatic endothelial conditional mutations in heparan sulfate biosynthesis to study the effects on tumor-lymphatic trafficking and lymph node metastasis. Lymphatic endothelial deficiency in N-deacetylase/N-sulfotransferase-1 (Ndst1), a key enzyme involved in sulfating nascent heparan sulfate chains, resulted in altered lymph node metastasis in tumor-bearing gene targeted mice. This occurred in mice harboring either a pan-endothelial Ndst1 mutation or an inducible lymphatic-endothelial specific mutation in Ndst1. In addition to a marked reduction in tumor metastases to the regional lymph nodes in mutant mice, specific immuno-localization of CCL21, a heparin-binding chemokine known to regulate leukocyte and possibly tumor-cell traffic, showed a marked reduction in its ability to associate with tumor cells in mutant lymph nodes. In vitro modified chemotaxis studies targeting heparan sulfate biosynthesis in lymphatic endothelial cells revealed that heparan sulfate secreted by lymphatic endothelium is required for CCL21-dependent directional migration of murine as well as human lung carcinoma cells toward the targeted lymphatic endothelium. Lymphatic heparan sulfate was also required for binding of CCL21 to its receptor CCR7 on tumor cells as well as the activation of migration signaling pathways in tumor cells exposed to lymphatic conditioned medium. Finally, lymphatic cell-surface heparan sulfate facilitated receptor-dependent binding and concentration of CCL21 on the lymphatic endothelium, thereby serving as a mechanism to generate lymphatic chemokine gradients. CONCLUSIONS: This work demonstrates the genetic importance of host lymphatic heparan sulfate in mediating chemokine dependent tumor-cell traffic in the lymphatic microenvironment. The impact on chemokine dependent lymphatic metastasis may guide novel therapeutic strategies.

Fulminant hepatic failure from primary hepatic lymphoma: successful treatment with orthotopic liver transplantation and chemotherapy.

Systemic lymphomas may involve the liver but rarely cause fulminant hepatic failure (FHF). Acute liver failure from primary hepatic lymphoma (PHL) is even less common with most patients succumbing to the sequelae of FHF before the correct diagnosis is made. We report a patient who underwent successful orthotopic liver transplant (OLT) and chemotherapy for FHF secondary to PHL. This previously-well male developed profound coagulopathy and encephalopathy 6 weeks after the onset of jaundice and fatigue. Workup failed to reveal the underlying cause of his liver failure and the patient soon required urgent OLT. Pathologic evaluation of his explanted liver revealed a malignant T-cell rich, large B-cell non-Hodgkin's lymphoma with widespread hepatocellular necrosis. The patient made an excellent clinical recovery and is undergoing CHOP-Rituxan chemotherapy. This scenario demonstrates that lymphoma should be considered in the differential diagnosis of FHF without clear etiology because of the potential for intervention with transplant and chemotherapy.