MFGE8 expression in uveal melanoma

Purpose MFGE8 (lactadherin) is a pro‐angiogenic glycoprotein of milk fat‐globule that has been involved in tumor progression in an angiogenesis dependent mouse model of carcinogenesis. In a study evaluating protein expression in membrane rafts of cutaneous melanoma at different stages of progression, MFGE8 expression was found to be enriched in membrane rafts of metastatic cutaneous melanoma cell lines. The purpose of this pilot study was to assess the expression of lactadherin in primary and metastatic uveal melanoma. Methods Expression of MFGE8 was assessed by immunohistochemistry in 10 primary and 10 metastatic non irradiated uveal melanoma. Western blot analysis was also performed in 3 uveal melanoma cells lines. Statistical analysis was performed using JMP software. Results MFGE8 expression was identified in only 2 primary uveal melanoma and in 7 metastatic uveal melanoma (p=0,0349). In the primary uveal melanoma, MFGE8 expression was cytoplasmic and membranous in one case and only cytoplasmic in one case. In the metastases, expression was cytoplasmic and membranous in 5 cases and only cytoplasmic in 2 cases. There were no correlation between MFGE8 expression and cell type. Confirmation of MGFE8 expression was identified by Western blot analysis in OCM3, OCM8 and 92,1 uveal melanoma cell lines. Conclusion This pilot study demonstrate for the first time the expression of MFGE8 in uveal melanoma and uveal melanoma cell lines. MFGE8 expression appears to be significantly higher in metastatic tumour and might play a role in tumour progression. Functional studies should be performed to better delineate the role of MFGE8 in uveal melanoma tumor progression.