Quantitative assessment of melanoma single-cell motility in vitro

The role of engineering approaches in analysing cancer invasion and metastasis

In the past decade, novel materials, probes and tools have enabled fundamental and applied cancer researchers to take a fresh look at the complex problem of tumour invasion and metastasis. These new tools, which include imaging modalities, controlled but complex in vitro culture conditions, and the ability to model and predict complex processes in vivo, represent an integration of traditional with novel engineering approaches; and their potential effect on quantitatively understanding tumour progression and invasion looks promising.

Mofarotene-induced inhibition of melanoma cell motility by increasing vinculin-containing focal contacts

Tumour cell motility, which is dependent on the organization of the cytoskeleton, is considered to play an important role in the spread of malignant melanoma. Therefore, retinoids, which are modulators of cytoskeletal organization, may affect the motile activity of melanoma cells. In this study, the effects of the arotinoid mofarotene on single cell motility and vinculin organization of the highly metastatic melanoma cell line K-1735-M2 were determined. Melanoma cells were cultivated in a temperature- and CO2-controlled microincubator, which was located on the microscope stage. Cell movements were evaluated quantitatively from time-lapse video recordings using an IBAS image analysis system. Vinculin distribution was evaluated using confocal laser scanning microscopy and a specially developed computerized image analysing program. In addition, melanoma cell invasion was tested on the embryonic chick heart model. Although 10 microM mofarotene did not reduce the translocative movements of melanoma cells, it significantly inhibited stationary motility, including fast plasma membrane movements and changes in shape. Mofarotene also showed a pronounced effect on the organization of vinculin-containing cell-substratum adhesion plaques. In retinoid-treated cells, the numbers of vinculin plaques per cell, and particularly those in the marginal areas of the cells, were significantly increased compared with untreated controls. Furthermore, the compound reduced the invasiveness of melanoma cells in a three-dimensional tissue culture model. In conclusion, our data demonstrate that mofarotene, an already almost forgotten synthetic retinoid, shows interesting effects on melanoma cells, which may be relevant for a slowdown of tumour spread.

Differential effects of synthetic sphingosine derivatives on melanoma cell motility, growth, adhesion and invasion in vitro

Cancer cell surface glycosphingolipids are considered to play a critical role in tumor growth and metastasis. However, the implications of glycoconjugates in the control of cell motility, which is considered to be involved in tumor invasion, are not fully understood. In this study, the effects of a series of synthetic sphingosine derivatives, obtained by the chemical transformation of azidosphingosines, on directional migration of K1735-M2 melanoma cells grown on type I collagen-coated surfaces were investigated. Following the application of 60 microM (2R, 3S, 4E)-2, 3-epimino-4-octadecen-3-ol (S4) the migration rate was 94 +/- 10 microns/day, compared with 377 +/- 22 microns/day in the control experiment. Six other analogues were not as potent. S4 also considerably down-modulated melanoma single cell motility. Inhibition of motile activity was associated with changes in the actin filament organization as well as with changes in the number and distribution of vinculin plaques. Moreover, the compound reduced the attachment abilities of melanoma cells to basement membrane Matrigel. Tumor cell invasion, however, was less affected and proliferation remained unimpaired after treatment with S4. These data suggest at least one intracellular mode of action of this particular synthetic sphingosine derivative by modulation of cytoskeletal organization. Melanoma cell motility and growth may be controlled independently via glycosphingolipids.