Previously we found that terfenadine, an H1 histamine receptor antagonist, acts as a potent apoptosis inducer in melanoma cells through modulation of Ca2+ homeostasis. In this report, focusing our attention on the apoptotic mechanisms activated by terfenadine, we show that this drug can potentially activate distinct intrinsic signaling pathways depending on culture conditions. Serum-deprived conditions enhance the cytotoxic effect of terfenadine and caspase-4 and -2 are activated upstream of caspase-9. Moreover, although we found an increase in ROS levels, the apoptosis was ROS independent. Conversely, terfenadine treatment in complete medium induced ROS-dependent apoptosis. Caspase-4, -2, and -9 were simultaneously activated and p73 and Noxa induction were involved. ROS inhibition prevented p73 and Noxa expression but not p53 and p21 expression, suggesting a role for Noxa in p53-independent apoptosis in melanoma cells. Finally, we found that terfenadine induced autophagy, that can promote apoptosis. These findings demonstrate the great potential of terfenadine to kill melanoma cells through different cellular signaling pathways and could contribute to define new therapeutic strategies in melanoma.
Previously, we found that the H1 histamine receptor antagonist diphenhydramine induces apoptosis in human acute T-lymphocytic leukemia cells. Since histamine has been shown to act as a growth factor in malignant melanoma cells, we decided to evaluate the in vitro effect of diphenhydramine and other H1 histamine receptor antagonists, such as terfenadine, astemizol and triprolidine on four malignant human melanoma cell lines. These antagonists were found to induce apoptotic cell death in all four melanoma cell lines. Apoptosis was determined by assessment of phosphatidylserine exposure on the surface of the cells and nuclear fragmentation. Importantly, H1 antagonist treatments did not adversely affect the viability of human melanocytes and murine fibroblasts at the same doses and duration of exposure. Treatment of melanoma cells with terfenadine induced DNA damage and caspases 2, 3, 6, 8 and 9 activation. Furthermore, the general caspase inhibitor (z-VAD-FMK) and a selective inhibitor of caspase-2 (z-VDVAD-FMK) protected melanoma cells from terfenadine-induced apoptosis. In contrast, the caspase-8 inhibitor (z-IETD-FMK) was ineffective. In addition, we found that mitochondria are involved in TEF-induced apoptosis, characterized by the dissipation of the mitochondrial transmembrane potential, the release of cytochrome c into the cytosolic compartment and caspase-9 activation. On the basis of these results we conclude that H1 histamine receptor antagonists induce apoptosis in human melanoma cells but not in normal melanocytes and embryonic murine fibroblasts; this apoptosis appears to be caspase-2-dependent and involves the mitochondrial pathway. The present results may contribute to the elaboration of novel therapeutic strategies for the treatment of malignant human melanoma.
In our previous works, we have demonstrated that terfenadine (TEF) induces DNA damage and apoptosis in human melanoma cell lines. In this present work, we have studied the effect of histamine on viability of A375 human melanoma cells and the cell-signalling pathways through which TEF may induce its apoptotic effect. We have found that exogenous histamine stimulates A375 melanoma cell proliferation in a dose- and time-dependent manner. Moreover, TEF-induced apoptosis seems to occur via other cellular pathways independent of the histamine-signalling system since co-treatment of histamine with TEF did not protect melanoma cells from the cytotoxic effect of TEF, and alpha fluoromethylhistidine did not induce the same cytotoxic effect of TEF. In addition, we have observed that knocking down the H1 histamine receptor (HRH1) by small interference RNA approach protects melanoma cells only slightly from TEF-induced apoptosis. To explore the molecular mechanisms responsible for histamine and TEF effect on the cell growth, we analysed intracellular cyclic nucleotides and Ca(2+) levels. TEF did not modify intracellular levels of cyclic adenosine 3',5'-monophosphate and cyclic guanine 3',5'-monophosphate; however, TEF induced a very sharp and sustained increase in cytosolic Ca(2+) levels in A375 melanoma cells. On the contrary, histamine did not modulate intracellular Ca(2+). TEF-induced Ca(2+) rise and apoptosis appear to be phospholipase C (PLC) dependent since neomycin and U73122, two inhibitors of PLC, abolished cytosolic Ca(2+) increase and protected the cells completely from cell death. Furthermore, inhibition of tyrosine kinase activity by genistein blocked cytosolic Ca(2+) rise and TEF-induced apoptosis. These results suggest that TEF modulates Ca(2+) homeostasis and induces apoptosis through other cellular pathways involving tyrosine kinase activity, independently of HRH1.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.