Angiogenesis is indispensable to
tumor development and proliferation. The aim of this study was to investigate whether the expression of
monocyte chemotactic protein-1 (MCP-1) and of
thymidine phosphorylase (TP) correlates with the angiogenesis and clinicopathologic features in cardiac
myxoma.
Paraffin-embedded specimens of 17 resected cardiac
myxomas were immunohistochemically stained for MCP-1,
CC chemokine receptor-2 (CCR-2), TP, CD31, and CD68. Correlations among MCP-1 expression, TP expression, microvessel count (determined by CD31 staining), macrophage count (determined by CD68 staining), and the clinicopathologic features of the patients were analyzed statistically. Immunohistochemical analysis revealed that MCP-1 and TP were expressed in
myxoma cells, as well as in stromal cells such as infiltrating cells, fibroblast-like cells and endothelial cells. CCR-2 was abundantly expressed in stromal infiltrating cells in all
myxomas and occasionally in the endothelial cells. In the
tumor stroma, the major source of MCP-1, TP and CCR-2 was macrophages, and the sites of positive staining for MCP-1, TP and CCR-2 matched in most of the
myxomas. Statistical analysis revealed that the proportions of MCP-1-positive
myxoma and stromal cells, and TP-positive
myxoma and stromal cells significantly correlated with increased microvessel count. The proportions of MCP-1-positive
myxoma and stromal cells significantly correlated with the proportion of TP-positive stromal cells. The mean microvessel count in
myxomas with both high
tumor and high stromal MCP-1 or TP expression was significantly higher than that in
myxomas with low
tumor and low stromal MCP-1 or TP expression. Small
tumors (< or =55 mm in diameter) exhibited high MCP-1 or TP expression, and the microvessel count in small
tumors was significantly higher than in large
myxomas. Although the difference was not significant,
myxomas with both high
tumor and high stromal MCP-1 expression had a higher macrophage count than other
myxomas. These results indicate that in cardiac
myxoma, MCP-1 and TP may be regarded as important angiogenic signals accompanying growth.