title: Melanoma spheroid formation involves laminin-associated vasculogenic mimicry.
abstract: Melanoma is a tumor where virulence is conferred on transition from flat (radial) to three-dimensional (tumorigenic) growth. Virulence of tumorigenic growth is governed by numerous attributes, including presence of self-renewing stem-like cells and related formation of patterned networks associated with the melanoma mitogen, laminin, a phenomenon known as vasculogenic mimicry. Vasculogenic mimicry is posited to contribute to melanoma perfusion and nutrition in vivo; we hypothesized that it may also play a role in stem cell-driven spheroid formation in vitro. Using a model of melanoma in vitro tumorigenesis, laminin-associated networks developed in association with three-dimensional melanoma spheroids. Real-time PCR analysis of laminin subunits showed that spheroids formed from anchorage-independent melanoma cells expressed increased α4 and β1 laminin chains and α4 laminin expression was confirmed by in situ hybridization. Association of laminin networks with melanoma stem cell-associated nestin and vascular endothelial growth factor receptor-1 also was documented. Moreover, knockdown of nestin gene expression impaired laminin expression and network formation within spheroids. Laminin networks were remarkably similar to those observed in melanoma xenografts in mice and to those seen in patient melanomas. These data indicate that vasculogenic mimicry-like laminin networks, in addition to their genesis in vivo, are integral to the extracellular architecture of melanoma spheroids in vitro, where they may serve as stimulatory scaffolds to support three-dimensional growth.
authors: Department of Dermatology, Brigham and Women's Hospital, Boston, Massachusetts.
authors: Allison R
authors: AR
authors: Larson
authors: Division of Dermatopathology, Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts.
authors: Chung-Wei
authors: CW
authors: Lee
authors: Division of Dermatopathology, Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts.
authors: Cecilia
authors: C
authors: Lezcano
authors: Division of Dermatopathology, Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts.
authors: Qian
authors: Q
authors: Zhan
authors: Division of Dermatopathology, Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts.
authors: John
authors: J
authors: Huang
authors: Department of Pathology, University of Massachusetts Medical Center, Worcester, Massachusetts.
authors: Andrew H
authors: AH
authors: Fischer
authors: Division of Dermatopathology, Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts. Electronic address: gmurphy@rics.bwh.harvard.edu.
authors: George F
authors: GF
authors: Murphy
mesh_terms: D000818:Animals; D015153:Blotting, Western; D045744:Cell Line, Tumor; D064593:Heterografts; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007797:Laminin / Q000378:metabolism*; D008545:Melanoma / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D016688:Mice, Inbred NOD; D014411:Neoplastic Stem Cells / Q000378:metabolism* / Q000473:pathology; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012878:Skin Neoplasms / Q000378:metabolism* / Q000473:pathology; D059016:Tumor Microenvironment / Q000502:physiology*
chemical_list: D007797:Laminin