Abstract 3464: Melanomas differentially regulate directionally persistent endothelial cell migration
Authors: Das Asha M. , Seynhaeve Ann LB , Rens Joost AP , Koning Gerben A. , Vermeulen Cindy E. , Eggermont Alexander MM , ten Hagen Timo L.M. 
Published: June 2012

Introduction: Cutaneous melanoma is the most aggressive form of skin cancer. Although early detection and surgical resection of the primary lesion could improve survival, metastatic melanoma is by large refractory to therapy and predicts poor prognosis.

Melanoma progression and metastatic dissemination relies on the process of angiogenesis. The angiogenic process is comprised of a stringent cascade of events ultimately resulting in a new vessel. Pathological (tumor) angiogenesis, however, is mediated by an array of angiogenic modulators produced by the tumor itself. Such tumor-associated modulators arbitrate the enhanced and awry proliferative, survival and migratory responses exhibited by endothelial cells, culminating in unregulated and unimpeded angiogenesis.

Project Description: In the current study, we evaluated the angiogenic potential of human melanoma cell lines, based on their ability to regulate directionally persistent endothelial cell (EC) migration. Melanoma conditioned medium (CM) from three human melanoma cell lines (BLM, Mel57, 1F6), differing in their degree of aggressiveness and clinical staging, were used to assess the migratory responses of ECs in a 2-D migration assay, previously established by our group. This assay involves the use of the ‘ring and barrier’ system, wherein the ECs were cultured in a migration ring to generate a confluent area at the periphery and a cell free area in the center. EC migration in response to the tested CMs was monitored real-time, and various migration parameters were determined. Additionally, CM size fractions were tested to delineate the differences observed in migratory responses of the ECs to the tested CMs.

Results and Conclusions: There was a clear correlation between EC migration and the degree of aggressiveness of the melanoma cell line used to generate the CM. While the CM of the highly aggressive BLM tumor cells induced a high migratory response in ECs, the CM of the less aggressive 1F6 cells had an inhibitory effect. The 1F6 CM was further size fractionated and it was observed that the factor/s responsible for this inhibition lay in the 10-30 kD range. Gene and protein expression verification helped identify a varied protein expression profile, which are secreted into the CM. Their expression inversely correlated with aggressiveness of the melanoma cell line and ability of the respective CMs to affect EC migration. CM of 1F6 cells silenced with shRNA induced EC migration, while both recombinant protein as well as the CM of BLM cells transfected with protein expressing plasmid mitigated EC migration. Taken together, these results demonstrate that the soluble protein in the CM inhibits the inherent propensity of endothelial cells to undergo directionally persistent migration and that this expression could impede EC melanoma-induced angiogenesis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3464. doi:10.1158/1538-7445.AM2011-3464