title: Pericyte-like location of GFP-tagged melanoma cells: ex vivo and in vivo studies of extravascular migratory metastasis.
abstract: Previous studies have demonstrated that some tumor cells occupy a pericyte-like location in melanoma, forming angio-tumoral complexes. We hypothesized that these tumor cells are migrating along the abluminal surface of the endothelium, a mechanism termed "extravascular migratory metastasis." In the present study, we have used human and murine melanoma cells that stably express enhanced green fluorescence protein (GFP) to examine, in an ex vivo co-culture model, melanoma cell interactions with vessels that have sprouted from rat aortic rings. We also used in vivo tumor growth on the chick chorioallantoic membrane (CAM) to observe the dissemination pathway of melanoma cells. In the ex vivo rat aorta system, we observed a pericyte-like location of tumor cells that were spreading along the vascular channels. For examination of the CAM in vivo, we have used the Lugassy preparation, allowing one to obtain striking images of the relationship between fluorescent GFP cells and microvessels. Melanoma cells were found cuffing the outside of vessels around the tumor. Tumor cells were observed along the vessels several centimeters from the tumor. Confocal microscopy and histopathology confirmed the pericyte-like location of tumor cells, without any observable intravasation. The results indicate that melanoma cells can migrate along the abluminal surface of vessels. This study also demonstrates that these models can provide quantitation analysis that may prove useful in elucidating the molecular interactions involved in extravascular migratory metastasis.
authors.affiliation: Department of Dermatology, The George Washington University Medical Center, Washington, District of Columbia, USA.
authors.forename: Claire
authors.initials: C
authors.lastname: Lugassy
authors.forename: Hynda K
authors.initials: HK
authors.lastname: Kleinman
authors.forename: Jean A
authors.initials: JA
authors.lastname: Engbring
authors.forename: Danny R
authors.initials: DR
authors.lastname: Welch
authors.forename: John F
authors.initials: JF
authors.lastname: Harms
authors.forename: Robyn
authors.initials: R
authors.lastname: Rufner
authors.forename: Ghanem
authors.initials: G
authors.lastname: Ghanem
authors.forename: Steven R
authors.initials: SR
authors.lastname: Patierno
authors.forename: Raymond L
authors.initials: RL
authors.lastname: Barnhill
mesh_terms: D000482:Allantois; D000818:Animals; D001011:Aorta / Q000502:physiology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology*; D002823:Chorion; D018920:Coculture Techniques; D049452:Green Fluorescent Proteins; D006801:Humans; D008164:Luminescent Proteins; D008546:Melanoma, Experimental / Q000098:blood supply / Q000473:pathology*; D051379:Mice; D018613:Microscopy, Confocal; D009362:Neoplasm Metastasis / Q000473:pathology*; D009389:Neovascularization, Pathologic; D009924:Organ Culture Techniques; D020286:Pericytes / Q000473:pathology*; D014162:Transfection
chemical_list: D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins