Histamine regulation of hyperplastic and neoplastic cell growth in cholangiocytes

Table 1 Effects of histamine and histamine receptors on cholangiocarcinomagrowth

	Expression level	Agonist effect	Antagonist effect	In vitro/in vivo model	Known or potential signaling mechanism
Histidine decarboxylase (HDC)	↑↑		↓↓ CCA growth	Both	Inhibits histamine synthesis
Monoamine oxidase-B (MAOB)	↓↓	Unknown	Unknown	In vitro	Unknown
Histamine	↑↑ secretion by CCA	↑↑ CCA growth	↓↓ CCA growth	Both	↑↓ VEGF expression
H1HR	↑↑	↑ CCA growth	↓↓ CCA growth	In vitro	Ca2+-mediated signaling
H2HR	↑↑	↔	↔	Both	Unknown
H3HR	↑↑	↓↓ CCA growth		Both	PKCa-dependent signaling
H4HR	↑↑	↓↓ CCA growth		In vitro	Integrin-dependent decreased invasion

CCA: Cholangiocarcinoma; HDC: Histidine decarboxylase; MAOB: Monoamine oxidase-B; HR: Histamine receptor; VEGF: Vascular endothelial growth factor.