RESUMO
Growth and dissemination of malignant melanoma has a profound impact on our population, and little is known concerning the mechanisms controlling this disease in humans. Evidence is provided that integrin alpha(v)beta3 plays a critical role in M21 melanoma tumor survival within human skin by a mechanism independent of its known role in angiogenesis. Antagonists of alpha(v)beta3 blocked melanoma growth by inducing tumor apoptosis. Moreover, M21 melanoma cell interactions with denatured collagen, a known ligand for alpha(v)beta3, caused a 5-fold increase in the relative Bcl-2:Bax ratio, an event thought to promote cell survival. Importantly, denatured collagen colocalized with alpha(v)beta3-expressing melanoma cells in human tumor biopsies, suggesting that alpha(v)beta3 interaction with denatured collagen may play a critical role in melanoma tumor survival in vivo.
Assuntos
Sobrevivência Celular/fisiologia , Melanoma/fisiopatologia , Proteínas de Neoplasias/fisiologia , Receptores de Vitronectina/fisiologia , Neoplasias Cutâneas/fisiopatologia , Animais , Anticorpos Monoclonais/farmacologia , Apoptose/fisiologia , Divisão Celular/fisiologia , Ensaio de Imunoadsorção Enzimática , Matriz Extracelular/metabolismo , Humanos , Melanoma/patologia , Camundongos , Camundongos SCID , Proteínas de Neoplasias/antagonistas & inibidores , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Receptores de Vitronectina/antagonistas & inibidores , Neoplasias Cutâneas/patologia , Células Tumorais Cultivadas , Vitronectina/metabolismo , Proteína X Associada a bcl-2RESUMO
Angiogenesis depends on both cell adhesion and proteolytic mechanisms. In fact, matrix metalloproteinase 2 (MMP-2) and integrin alphavbeta3 are functionally associated on the surface of angiogenic blood vessels. A fragment of MMP-2, which comprises the C-terminal hemopexin-like domain, termed PEX, prevents this enzyme binding to alphavbeta3 and blocks cell surface collagenolytic activity. PEX blocks MMP-2 activity on the chick chorioallantoic membrane where it disrupts angiogenesis and tumor growth. Importantly, a naturally occurring form of PEX can be detected in vivo in conjunction with alphavbeta3 expression in tumors and during developmental retinal neovascularization. Levels of PEX in these vascularized tissues suggest that it interacts with endothelial cell alphavbeta3 where it serves as a natural inhibitor of MMP-2 activity, thereby regulating the invasive behavior of new blood vessels.
Assuntos
Gelatinases/metabolismo , Metaloendopeptidases/metabolismo , Neovascularização Fisiológica/fisiologia , Fragmentos de Peptídeos/metabolismo , Receptores de Vitronectina/metabolismo , Alantoide/enzimologia , Animais , Linhagem Celular , Embrião de Galinha , Córion/enzimologia , Colágeno/metabolismo , Cricetinae , Endotélio Vascular/citologia , Gelatinases/análise , Gelatinases/genética , Gelatinases/farmacologia , Hemopexina , Humanos , Metaloproteinase 2 da Matriz , Melanoma/irrigação sanguínea , Melanoma/patologia , Metaloendopeptidases/análise , Metaloendopeptidases/genética , Metaloendopeptidases/farmacologia , Camundongos , Neovascularização Patológica , Neovascularização Fisiológica/efeitos dos fármacos , Fragmentos de Peptídeos/análise , Fragmentos de Peptídeos/farmacologia , Ligação Proteica , Proteínas Recombinantes de Fusão , Retina/enzimologia , Vasos Retinianos/enzimologia , Células Tumorais CultivadasRESUMO
SUMMARY: Cellular invasion depends on cooperation between adhesive and proteolytic mechanisms. Evidence is provided that the matrix metalloproteinase MMP-2 can be localized in a proteolytically active form on the surface of invasive cells, based on its ability to bind directly integrin alpha v beta 3. MMP-2 and alpha v beta 3 were specifically colocalized on angiogenic blood vessels and melanoma cells in vivo. Expression of alpha v beta 3 on cultured melanoma cells enabled their binding to MMP-2 in a proteolytically active form, facilitating cell-mediated collagen degradation. In vitro, these proteins formed an SDS-stable complex that depended on the noncatalytic C-terminus of MMP-2, since a truncation mutant lost the ability to bind alpha v beta 3. These findings define a single cell-surface receptor that regulates both matrix degradation and motility, thereby facilitating directed cellular invasion.