Original article. Cinnamic aldehyde inhibits proliferation and invasion in a well-defined 3-dimensional culture of human cutaneous melanoma cells in tissue engineered-skin

Background: Tissue-engineered skin can be used not only to cover and repair skin damage, but also as a model to test the efficacy of drugs and cosmetics.

Objective: To establish a 3-dimensional (3D) culture model of skin melanoma invasion using A375 melanoma cells in vitro for studying melanoma and with which to conduct preliminary evaluation of therapeutic drugs. Here we evaluated the efficacy of cinnamic aldehyde to inhibit tumor cell growth in our 3D model of malignant melanoma.

Methods: Melanoma cells A375 were inoculated onto the surface of tissue-engineered skin and cultured at the air-liquid interface. On day 5, cinnamic aldehyde (20 μ☐) was added to the culture medium. Skin samples cultured for different days were stained with hematoxylin and eosin and observed using transmission electron microscopy. Immunohistochemical staining of E-cadherin, proliferating cell nuclear antigen (PCNA), and matrix metalloproteinase (MMP)-9 was conducted separately.

Results: A large number of A375 cell clumps had invaded the deep dermis by day 15. The tumor cells formed clumps through the desmosomes and connected with the surrounding fibroblasts through cell junctions. While the expression of E-cadherin was lost in the tumor cells, expression of MMP-9 and PCNA increased with increasing depth of invasion. Cinnamic aldehyde inhibited the proliferation and invasion of melanoma cells in the 3D culture model. Expression of MMP-9 and PCNA significantly decreased in melanoma cells in the model treated with cinnamic aldehyde.

Conclusion: The 3D culture model successfully retains the biological proliferation and invasion characteristics of the malignant melanoma cells and can be used as a system to study further the biological characteristics of malignant melanoma and to evaluate the efficacy of drug treatment. Cinnamic aldehyde and compounds of its class may prove useful treatments for patients with advanced melanomas.