INTERRELATION OF MOTILITY, CYTOSKELETAL ORGANIZATION AND GAP JUNCTIONAL COMMUNICATION WITH INVASIVENESS OF MELANOCYTIC CELLS IN-VITRO

Intercellular communication and the active movement of malignant cells into and through host tissue barriers play a critical role during the complex process of tumor invasion. Motile activity, cytoskeletal acti n and vinculin organization as well as gap junctional communication of in vivo benign and malignant melanocytes were compared and related to in vitro invasiveness. Normal melanocytes, Melan-a, showed significan tly less motile activity, a higher organization of the actin cytoskele ton and more vinculin-containing cell-substratum adhesion plaques than highly metastatic melanoma cells, K1735-M2. There was no pronounced d ifference in gap junctional communication under comparable culture con ditions. However, cultivation of Melan-a cells in a conventional melan ocyte growth medium containing the tumor promoter 12-O-tetradecanoylph orbol-13-acetate (TPA) enhanced intercellular communication. Melanocyt es were less invasive than melanoma cells both in the embryonic chick heart model and in the Matrigel invasion assay. The least invasive act ivity was determined for melanocytes cultivated in TPA-deficient mediu m indicating that the medium supplement TPA stimulates invasion. The c omparison of certain in vitro properties of both melanocytic cell line s revealed a positive correlation of motility with in vitro invasion, whereas an inverse correlation was found for the degree of actin filam ent organization as well as for the number of vinculin plaques. Gap ju nctional communication was not directly related to in vitro invasivene ss.