Histamine H1- and H4-receptor expression in human colon-derived cell lines

Abstract

In previous studies, we demonstrated the involvement of H 4 R in inflammatory bowel disease (IBD) and IBD-associated colon cancer in mice and could ascribe H 4 R-mediated histamine function to colon epithelial cells. The transferability of obtained data to humans is however lacking. Functional expression of H 4 R on colon epithelial cells is a prerequisite to pursue the hypothesis of involvement of H 4 R in carcinogenesis. Thus, we here compared the expression of histamine receptor subtypes in a series of cell lines. Out of these, three colon-derived cell lines displaying different combinations of H 1 R and H 4 R expression were submitted to functional analyses. Human hematopoietic HMC-1, HL-60, and U937, lung-derived A549 and Calu-3, and colorectal LoVo, SW 480, Caco-2, HT-29, and HCT116 cells were included in the study. mRNA expression was quantified by RT-qPCR. For functional analyses, Caco-2, HT-29, and HCT116 cells were treated by incubation with 1 – 10 µM histamine in the presence or absence of selective histamine receptor antagonists. Calcium mobilization, cAMP accumulation, and cell proliferation were measured by fluorimetry, mass spectrometry, and real-time bioimpedance measurements, respectively. Histamine receptor expression was heterogeneous in the cell lines tested. In most cell lines, we detected H 1 R mRNA while H 4 R mRNAs were found only occasionally. The colon-derived epithelial cell lines LoVo, SW480, and HT-29 expressed H 1 R mRNA exclusively, while in HCT116 cells H 1 R and H 4 R mRNAs and in CaCo-2 H 2 R mRNA were detectable. Subsequent functional analyses in HT29, Caco-2, and HCT116 cells, however, indicated that only HT-29 responded to histamine stimulation, by means of H 1 R. For a detailed analysis of histamine receptor function, esp. that of H 1 R and H 4 R, in human colon-derived cell lines, the cell lines tested here are not fully convenient unless genetically modified.

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