Comparison of Histamine Content in B16F10 Melanoma Cells and Non‐tumorigenic Melan‐A Melanocytes

Abstract

Based on earlier suggestions for a possible involvement of histamine in certain cancers, we compared previously the expression of the histamine‐forming enzyme, histidine decarboxylase (HDC), in B16F10 murine melanoma cells and non‐cancerous murine Melan‐A melanocytes. Consistent with an up‐regulated endogenous histaminergic system in cancer cells, immunohistochemistry and Western blot analysis for HDC demonstrated markedly greater expression of HDC protein in B16F10 melanoma cells than in the Melan‐A cells. In the present study, we compared the levels of histamine in the two cell types using immunohistochemistry and enzyme immunoassay (EIA). Markedly greater immunofluorescent staining for histamine was observed in B16F10 than in pair‐stained Melan‐A cells. Consistent with these results, histamine levels measured using EIA were 280‐fold higher (p<0.001) in B16F10 (229 +15 pg/mg protein) than in Melan‐A (0.83+0.03 pg/mg protein) cells. Together with previous data, the increased HDC expression and histamine levels within the B16F10 melanoma cells support the presence of a functional, up‐regulated, endogenous histaminergic system in melanoma cells. Further experiments are needed to determine if the up‐regulated endogenous histaminergic system has an important function in melanoma cells to regulate cell migration and invasiveness.