V3 Versican Isoform Alters the Behavior of Human Melanoma Cells by Interfering with CD44/ErbB-dependent Signaling

Daniel Hernández,Laia Miquel-Serra,María-José Docampo,Anna Marco-Ramell,Jennifer Cabrera,Angels Fabra,Anna Bassols

doi:10.1074/jbc.m110.127522

Abstract

Versican is a hyaluronan-binding, extracellular chondroitin sulfate proteoglycan produced by several tumor types, including malignant melanoma, which exists as four different splice variants. The short V3 isoform contains the G1 and G3 terminal domains of versican that may potentially interact directly or indirectly with the hyaluronan receptor CD44 and the EGFR, respectively. We have previously described that overexpression of V3 in MeWo human melanoma cells markedly reduces tumor cell growth in vitro and in vivo. In this study we have investigated the signaling mechanism of V3 by silencing the expression of CD44 in control and V3-expressing melanoma cells. Suppression of CD44 had the same effects on cell proliferation and cell migration than those provoked by V3 expression, suggesting that V3 acts through a CD44-mediated mechanism. Furthermore, CD44-dependent hyaluronan internalization was blocked by V3 expression and CD44 silencing, leading to an accumulation of this glycosaminoglycan in the pericellular matrix and to changes in cell migration on hyaluronan. Furthermore, ERK1/2 and p38 activation after EGF treatment were decreased in V3-expressing cells suggesting that V3 may also interact with the EGFR through its G3 domain. The existence of a EGFR/ErbB2 receptor complex able to interact with CD44 was identified in MeWo melanoma cells. V3 overexpression resulted in a reduced interaction between EGFR/ErbB2 and CD44 in response to EGF treatment. Our results indicate that the V3 isoform of versican interferes with CD44 and the CD44-EGFR/ErbB2 interaction, altering the signaling pathways, such as ERK1/2 and p38 MAPK, that regulate cell proliferation and migration.

Highlights

To the proliferative, adhesive and migratory state of tumor cells, as well as being an important modulator of tumor cell attachment to the interstitial stromal matrix of the tumor
Melanoma Cells—Because the V3 isoform maintains the ability of the other members of the versican family for binding to HA through its G1 domain, and, under the hypothesis that some of the effects of V3 in MeWo melanoma cells could be mediated by CD44, we silenced the expression of CD44 in
We described for the first time a high expression of the large isoforms of versican V0 and V1 by malignant melanoma cells [23]

Summary

Introduction

To the proliferative, adhesive and migratory state of tumor cells, as well as being an important modulator of tumor cell attachment to the interstitial stromal matrix of the tumor This wide range of functions has been attributed to its ability to interact with other extracellular matrix and cell surface components through its three structural domains: the N-terminal region (G1 domain) that binds hyaluronan (HA), the central G2 domain that carries the glycosaminoglycan chains (GAG-␣ and GAG-␤) and the C-terminal globular region (G3 domain) that interacts with simple carbohydrates, glycosaminoglycans, and other proteins such as tenascin. The decrease in cell proliferation correlated with a lower activation of the proliferationrelated ERK1/2 pathway in response to EGF [26] and a delay in cell cycle progression [25] These results raised the possibility that V3 isoform could exert its effects through changes in the pericellular coat by competing with the larger chondroitin sulfate-bearing V0 and JANUARY 14, 2011 VOLUME 286 NUMBER 2. Despite this possible competition mechanism, a direct effect of V3 isoform independent of the presence of the large isoforms should exist, because the diminished proliferation as well as other altered cell functions could be readily observed in cells that lack any versican isoform

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