We reported recently that the inflammatory
cytokine tumour
necrosis factor alpha (
TNF-alpha) can upregulate
integrin expression, cell attachment and invasion of cells through
fibronectin in a human
melanoma cell line (HBL). Furthermore, the actions of
TNF-alpha were suppressed by the addition of an anti-inflammatory
peptide alpha-melanocyte-stimulating hormone (
alpha-MSH). In the current study, we extend this work investigating to what extent
TNF-alpha might stimulate
melanoma invasion by promoting cell migration and whether
alpha-MSH is also inhibitory. Two human
melanoma cell lines were examined in vitro (HBL and C8161) using a scratch migration assay. Analysis using either time-lapse video microscopy or imaging software analysis of migrating 'fronts' of cells revealed that C8161 cells migrated more rapidly than HBL cells. However, when cells were stimulated with
TNF-alpha both cell types responded with a significant increase in migration distance over a 16-26 h incubation time.
alpha-Melanocyte-stimulating hormone had an inhibitory effect on
TNF-alpha-stimulated migration for HBL cells, completely blocking migration
at 10(-9) M. In contrast, C8161 cells did not respond to
alpha-MSH (as these cells have a loss-of-function
melanocortin-1 receptor). However, stable transfection of C8161 cells with the wild-type
melanocortin-1 receptor produced cells whose migration was significantly inhibited by
alpha-MSH. In addition, the use of a neutralising antibody to the beta(1)-integrin subunit significantly reduced migration in both cell types. This data therefore supports an inflammatory environment promoting
melanoma cell migration, and in addition shows that
alpha-MSH can inhibit inflammatory stimulated migration. The data also support a fundamental role of the beta(1)-integrin receptor in
melanoma cell migration.