Autoregulation of endothelin-1 secretion by cultured human keratinocytes via the endothelin B receptor

doi:10.1016/0167-4889(94)90282-8

Biochimica et Biophysica Acta (BBA) - Molecular Cell Research

Volume 1224, Issue 3, 30 December 1994, Pages 454-458

https://doi.org/10.1016/0167-4889(94)90282-8 Get rights and content

Abstract

We investigated endothelin-1 (ET-1) receptor expression on normal human keratinocytes (HK). We show that HK express the ET_B receptor isoform and respond to ET-1 with a 2.7-fold increase in intracellular free calcium. HK did not respond to ET-1 with increased proliferation; however, 30 nM ET-1 caused a 51.7% decrease in ET-1 accumulation in HK-conditioned medium. We propose that HK ET-1 receptors function in autocrine regulation of ET-1 secretion.

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Re-expression of the methylated EDNRB gene in oral squamous cell carcinoma attenuates cancer-induced pain
2011, Pain
Citation Excerpt :
Support for the second analgesic mechanism comes from our finding that ET-1 levels in the cell supernatant are significantly lower in oral SCC re-expressing the ETB receptor. ETB receptors have a known role in ET-1 clearance and inhibiting ET-1 secretion in keratinocytes [26,38]. Our previous studies in a mouse oral SCC model have shown that ET-1 protein and mRNA concentrations are markedly elevated in oral SCC tumors.
Endothelin-1 is a vasoactive peptide that activates both the endothelin A (ET_A) and endothelin B (ET_B) receptors, and is secreted in high concentrations in many different cancer environments. Although ET_A receptor activation has an established nociceptive effect in cancer models, the role of ET_B receptors on cancer pain is controversial. EDNRB, the gene encoding the ET_B receptor, has been shown to be hypermethylated and transcriptionally silenced in many different cancers. In this study we demonstrate that EDNRB is heavily methylated in human oral squamous cell carcinoma lesions, which are painful, but not methylated in human oral dysplasia lesions, which are typically not painful. ET_B mRNA expression is reduced in the human oral squamous cell carcinoma lesions as a consequence of EDNRB hypermethylation. Using a mouse cancer pain model, we show that ET_B receptor re-expression attenuates cancer-induced pain. These findings identify EDNRB methylation as a novel regulatory mechanism in cancer-induced pain and suggest that demethylation therapy targeted at the cancer microenvironment has the potential to thwart pain-producing mechanisms at the source, thus freeing patients of systemic analgesic toxicity.
Peripheral endothelin B receptor agonist-induced antinociception involves endogenous opioids in mice
2010, Pain
Citation Excerpt :
Unlike the G proteins associated with ETAR, ETBR predominantly interacts with Gαi1, Gαi2, and Gαq/11. [61] ETBR is expressed by various normal cell types [47], including dorsal root ganglion satellite cells, nonmyelinating ensheathing Schwann cells [51], skin keratinocytes [33,67], and human gingival keratinocytes. [23] ETBR is also found on different cancer cells, such as melanoma [34], breast carcinoma [2,65], and oral squamous carcinoma cell line SCC25 [5].
Endothelin-1 (ET-1) produced by various cancers is known to be responsible for inducing pain. While ET-1 binding to ETAR on peripheral nerves clearly mediates nociception, effects from binding to ETBR are less clear. The present study assessed the effects of ETBR activation and the role of endogenous opioid analgesia in carcinoma pain using an orthotopic cancer pain mouse model. mRNA expression analysis showed that ET-1 was nearly doubled while ETBR was significantly down-regulated in a human oral SCC cell line compared to normal oral keratinocytes (NOK). Squamous cell carcinoma (SCC) cell culture treated with an ETBR agonist (10⁻⁴ M, 10⁻⁵ M, and 10⁻⁶ M BQ-3020) significantly increased the production of β-endorphin without any effects on leu-enkephalin or dynorphin. Cancer inoculated in the hind paw of athymic mice with SCC induced significant pain, as indicated by reduction of paw withdrawal thresholds in response to mechanical stimulation, compared to sham-injected and NOK-injected groups. Intratumor administration of 3 mg/kg BQ-3020 attenuated cancer pain by approximately 50% up to 3 h post-injection compared to PBS-vehicle and contralateral injection, while intratumor ETBR antagonist BQ-788 treatment (100 and 300 μg/kg and 3 mg/kg) had no effects. Local naloxone methiodide (500 μg/kg) or selective μ-opioid receptor antagonist (CTOP, 500 μg/kg) injection reversed ETBR agonist-induced antinociception in cancer animals. We propose that these results demonstrate that peripheral ETBR agonism attenuates carcinoma pain by modulating β-endorphins released from the SCC to act on peripheral opioid receptors found in the cancer microenvironment.
Dissecting the functional significance of endothelin A receptors in peripheral nociceptors in vivo via conditional gene deletion
2010, Pain
Citation Excerpt :
In addition to the DRG, ETA and ETB receptors are expressed on a variety of cell types which can modulate nociception, e.g. immune cells, keratinocytes, and endothelial cells [12,22,37,50]. Keratinocytes can be directly activated upon application of ET1 and lead to the release of neuroactive mediators, such as ATP, CGRP, glutamate, interleukin 8, prostaglandin E2 and ET1 itself [22,38,45,46]. Furthermore, neutrophil granulocytes, which are also capable of releasing a variety of pro-nociceptive substances, are directly activated by endothelins [9,15,50].
The peptide endothelin-1 (ET1), which was originally identified as a vasoconstrictor, has emerged as a critical regulator of a number of painful conditions, including inflammatory pain and tumor-associated pain. There is considerable pharmacological evidence supporting a role for endothelin A receptors (ET_A) in mediating ET1-induced pro-algesic functions. ET_A receptors are expressed in small-diameter nociceptive neurons, but also found in a variety of other cell types in peripheral tissues, including immune cells, keratinocytes, endothelial cells, which have the potential to modulate nociception. To elucidate the functional contribution of ET_A receptors expressed in sensory neurons towards the functions of the ET1 axis in pathological pain states, we undertook a conditional gene deletion approach to selectively deplete expression of ET_A in sensory nerves, preserving expression in non-neural peripheral tissues; the expression of ET_B remained unchanged. Behavioural and pharmacological experiments showed that only late nociceptive hypersensitivity caused by ET1 is abrogated upon a loss of ET_A receptors on nociceptors and further suggest that ET1-induced early nociceptive hypersensitivity involves activation of ET_A as well as ET_B receptors in non-neural peripheral cells. Furthermore, in the context of alleviation of cancer pain and chronic inflammatory pain by ET_A receptor antagonists, we observed in corresponding mouse models that the contribution of ET_A receptors expressed in nociceptors is most significant. These results help understand the role of ET_A receptors in complex biological processes and peripheral cell–cell interactions involved in inflammatory and tumor-associated pain.
Beyond neurons: The complex sources of pain transduction
2010, Pain
Role of ET<inf>A</inf> and ET<inf>B</inf> endothelin receptors on endothelin-1-induced potentiation of nociceptive and thermal hyperalgesic responses evoked by capsaicin in rats
2009, Neuroscience Letters
Increasing evidence indicates that endothelin-1 (ET-1) activates nociceptive neurons and sensitizes them to different noxious stimuli, but involvement of TRPV1-dependent mechanisms in mediation of such effects is not yet fully understood. Here we report that intraplantar (i.pl.) injection of ET-1 (10 pmol) into the hind paw of rats induced overt nociceptive behavior over the first hour, followed by a slowly developing thermal hyperalgesia, lasting from 3 to 8 h after injection. Both effects were also induced by similar injections of capsaicin (10–1000 pmol), but these responses were shorter lasting than those caused by ET-1. Local pre-treatment with the TRPV1 antagonist capsazepine (30 nmol, i.pl.) reduced only the thermal hyperalgesia induced by ET-1, but fully suppressed both responses to capsaicin (1000 pmol). Injection of a sub-threshold dose of ET-1 (0.1 pmol, i.pl.) prior to capsaicin (1 pmol, i.pl.) markedly sensitized the hind paw to the overt nociceptive and thermal hyperalgesic effects of the later. The potentiation of capsaicin-induced nociception by ET-1 was abolished by prior i.pl. injection of BQ-123 (ET_A receptor antagonist, 10 nmol), but unaffected by BQ-788 (ET_B receptors antagonist, 10 nmol), whereas the enhancement of capsaicin-induced hyperalgesia by ET-1 was attenuated by both antagonists. Therefore, differently to what has been reported in mice, in rats TRPV1 receptors contribute selectively to thermal hyperalgesia, but not overt nociception, induced by ET-1. Importantly, although ET-1 augments capsaicin-induced overt nociception and thermal hyperalgesia, potentiation of the former relies solely on ET_A receptor-mediated signaling mechanisms, whereas both receptors contribute to the latter.
Endothelin Receptors and Pain
2009, Journal of Pain
Citation Excerpt :
Isolated sensory neurons are stimulated by ET-1 to elevate cGMP60 and to release neuropeptides and glutamate, actions probably resulting from an ETA-dependent elevation of intracellular [Ca+2].60,272 Primary cultures of keratinocytes also are stimulated by ET-1, with separate studies showing ETB receptor-mediated release of the opioid peptide β-endorphin129 and of ET-1 itself.265,266 The latter comprises an autocrine loop, but with a biphasic dynamic response; immediately on exposure to ET-1, keratinocytes show elevated intracellular Ca2+, which would be expected to cause an acute increase in the release of many substances, including ET-1 itself, but after prolonged (24 hours) exposure to ET-1, its basal release by keratinocytes is suppressed, probably by negative feedback on its synthesis.266
The endogenous endothelin (ET) peptides participate in a remarkable variety of pain-relatedprocesses. Pain that is elevated by inflammation, by skin incision, by cancer, during a Sickle Cell Disease crisis and by treatments that mimic neuropathic and inflammatory pain and are all reduced by local administration of antagonists of endothelin receptors. Many effects of endogenously released endothelin are simulated by acute, local subcutaneous administration of endothelin, which at very high concentrations causes pain and at lower concentrations sensitizes the nocifensive reactions to mechanical, thermal and chemical stimuli.
In this paper we review the biochemistry, second messenger pathways and hetero-receptor coupling that are activated by ET receptors, the cellular physiological responses to ET receptor activation, and the contribution to pain of such mechanisms occurring in the periphery and the CNS. Our goal is to frame the subject of endothelin and pain for a broad readership, and to present the generally accepted as well as the disputed concepts, including important unanswered questions.

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^☆: This work was supported by: NIH grant KO8 ARO1868-02 (J.J.Y.), American Cancer Society Research Grant CD513 (M.A.K.), The Robert Wood Johnson Foundation and the Scleroderma Research Foundation (M.R.Z.).

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Rapid reportAutoregulation of endothelin-1 secretion by cultured human keratinocytes via the endothelin B receptor☆

Abstract

J. Invest. Dermatol.

J. Invest. Dermatol.

J. Biol. Chem.

J. Invest. Dermatol.

J. Biol. Chem.

J. Biol. Chem.

Atherosclerosis

Biochem. Biophys. Res. Commun.

J. Biol. Chem.

Biochem. Biophys. Res. Commun.

Trends Pharmacol. Sci.

Arch. Dermatol. Res.

Br. J. Cancer

Melanins and Melanogenesis

Rapid report
Autoregulation of endothelin-1 secretion by cultured human keratinocytes via the endothelin B receptor☆