P19-derived neuronal cells express H1, H2, and H3 histamine receptors: a biopharmaceutical approach to evaluate antihistamine agents

Histamine is a biogenic amine implicated in various biological and pathological processes. Convenient cellular models are needed to screen and develop new antihistamine agents. This report aimed to characterize the response of neurons differentiated from mouse P19 embryonal carcinoma cells to histamine treatment, and to investigate the modulation of this response by antihistamine drugs, vegetal diamine oxidase, and catalase. The exposure of P19 neurons to histamine reduced cell viability to 65% maximally. This effect involves specific histamine receptors, since it was prevented by treatment with desloratadine and cimetidine, respectively, H-1 and H-2 antagonists, but not by the H-3 antagonist ciproxifan. RT-PCR analysis showed that P19 neurons express H-1 and H-2 receptors, and the H-3 receptor, although it seemed not involved in the histamine effect on these cells. The H-4 receptor was not expressed. H-1 and H-2 antagonists as well as vegetal diamine oxidase diminished the intracellular Ca2+ mobilization triggered by histamine. The treatment with vegetal diamine oxidase or catalase protected against mortality and a significant reduction of H2O2 level, generated from the cells under the histamine action, was found upon treatments with desloratadine, cimetidine, vegetal diamine oxidase, or catalase. Overall, the results indicate the expression of functional histamine receptors and open the possibility of using P19 neurons as model system to study the roles of histamine and related drugs in neuronal pathogenesis. This model is less expensive to operate and can be easily implemented by current laboratories of analysis and by Contract Research Organizations

The function of tetrahydropteroylpolyglutamates with formiminotransferase-cyclodeaminase /

Formiminotransferase (EC 2.1.2.5)-cyclodeaminase (EC 4.3.1.4) catalyzes two sequential H(,4)folate-dependent reactions. With derivatives of the H(,4)folate substrate having 4,5, or 6 glutamyl residues, the formiminoH(,4)pteroylpolyglutamate formed by the transferase activity is preferentially transferred (channeled) to the deaminase site rather than released into the solution. This channeling is essentially complete with the pentaglutamate derivative. The enzyme has highest affinity for the hexaglutamate as measured by K(,d) and K(,m), but does not show specificity for a given polyglutamate as measured by V(,m)/K(,m). The results indicate that steric length of the polyglutamate chain, not simply affinity, is critical for optimal channeling. Binding studies demonstrate four sites for the binding of H(,4)pteroylpolyglutamates to the native octamer, suggesting the formation of sites between subunits. The transferase and deaminase sites are kinetically independent, but share a common polyglutamate subsite. The results support the concept that the polyglutamate chain anchors the H(,4)folate molecule during its transfer between active sites

Modification of Occupational Exposures on Bladder Cancer Risk by Common Genetic Polymorphisms

Few studies have demonstrated gene/environment interactions in cancer research. Using data on high-risk occupations for 2258 case patients and 2410 control patients from two bladder cancer studies, we observed that three of 16 known or candidate bladder cancer susceptibility variants displayed statistically significant and consistent evidence of additive interactions; specifically, the GSTM1 deletion polymorphism (Pinteraction ≤ .001), rs11892031 (UGT1A, Pinteraction = .01), and rs798766 (TMEM129-TACC3-FGFR3, Pinteraction = .03). There was limited evidence for multiplicative interactions. When we examined detailed data on a prevalent occupational exposure associated with increased bladder cancer risk, straight metalworking fluids, we also observed statistically significant additive interaction for rs798766 (TMEM129-TACC3-FGFR3, Pinteraction= .02), with the interaction more apparent in patients with tumors positive for FGFR3 expression. All statistical tests were two-sided. The interaction we observed for rs798766 (TMEM129-TACC3-FGFR3) with specific exposure to straight metalworking fluids illustrates the value of integrating germline genetic variation, environmental exposures, and tumor marker data to provide insight into the mechanisms of bladder carcinogenesis