The expression of non-mast histamine in tumor associated microvessels in human colorectal cancers.

Angiogenesis is essential for the growth, expansion and metastasis of human colorectal cancers (CRCs). Histamine produced by mast cells is a potent proangiogenic factor. However, the significance of non-mast cell expressing histamine in the tumor microenvironment remains unknown. In this study, we evaluated the histamine positive microvessels with the specific marker for biosynthesis of histamine L-histidine decarboxylase (HDC) in the CRC tumor microenvironment. The relationship between HDC positive microvessel density (HDC-MVD) and clinical pathological parameters was assessed. The results revealed that HDC-MVD in the tumor microenvironment of CRCs was significantly increased as compared with the controls. CRC patients with lymph node invasion had a particularly higher density of HDC-MVD than those without. The density of HDC-MVD accounted for ~79 % of CD34 positive MVD in CRCs and double IHC analysis demonstrated that these HDC positive microvessels were mostly CD34 positive microvessels and with a high proliferative activity. Our results suggest that histamine expressed in microvessels could be an additional cellular source and involved in the cancer invasion through promoting angiogenesis in human CRCs.