Drug Repurposing: The Anthelmintics Niclosamide and Nitazoxanide Are Potent TMEM16A Antagonists That Fully Bronchodilate Airways

Miner, Kent; Labitzke, Katja; Liu, Benxian; Wang, Paul; Henckels, Kathryn; Gaida, Kevin; Elliott, Robin; Chen, Jian Jeffrey; Liu, Longbin; Leith, Anh; Trueblood, Esther S.; Hensley, Kelly; Xia, Xing-Zhong; Homann, Oliver; Bennett, Brian D.; Fiorino, Mike; Whoriskey, John; Yu, Gang; Escobar, Sabine; Wong, Min‐Liang; Born, Teresa L.; Budelsky, Alison; Comeau, Mike; Smith, Dirk E.; Phillips, Jonathan E.; Johnston, James A.; McGivern, Joseph G.; Weikl, Kerstin; Powers, David; Kunzelmann, Karl; Mohn, Deanna; Hochheimer, Andreas; Sullivan, John K.

doi:10.3389/fphar.2019.00051

Cited by 116 publications

(101 citation statements)

References 112 publications

(151 reference statements)

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“…The ability of different drugs to activate overexpressed TMEM16A may be due to a higher sensitivity of overexpressed channels for intracellular Ca 2+ . This is supported by the basal activity of overexpressed Niclosamide was reported as potent inhibitor of TMEM16A that also inhibits TMEM16F [9,25]. Because niclosamide inhibits ATP-induced rise in [Ca 2+ ] i [25], we examined if the compound truly blocks TMEM16A channels directly and not or not only indirectly by affecting intracellular Ca 2+ levels.…”

Section: Activators Of Tmem16a Act Differently On Endogenous and Overmentioning

confidence: 88%

“…TMEM16A is also expressed in airway smooth muscle (ASM) [3][4][5][6]. In both asthma and cystic fibrosis (CF), and upon exposure of airway epithelial cells to bacterial components, TMEM16A is strongly upregulated, particularly in cells of submucosal glands [7][8][9]. In CF, impaired function of the cystic fibrosis transmembrane conductance regulator (CFTR) leads to a defect in epithelial Cl − secretion, causing reduced airway surface liquid (ASL) with the consequence of a dehydrated sticky mucus and possibly low ASL pH (discussed in [2].…”

Section: Introductionmentioning

confidence: 99%

“…Pharmacological activation of TMEM16A is thought to compensate for the absent CFTR-dependent Cl − secretion in CF, and therefore may represent a CFTR mutation-agnostic therapy [10]. Other studies found a role of TMEM16A for ASM contraction [6,9,11]. Such a role of TMEM16A is particularly evident under inflammatory conditions like asthma, when TMEM16A is strongly upregulated in the ASM.…”

Section: Introductionmentioning

confidence: 99%

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Pharmacological Inhibition and Activation of the Ca2+ Activated Cl− Channel TMEM16A

Centeio

Cabrita

Benedetto

et al. 2020

IJMS

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TMEM16A is a Ca 2+ activated Cl − channel with important functions in airways, intestine, and other epithelial organs. Activation of TMEM16A is proposed as a therapy in cystic fibrosis (CF) to reinstall airway Cl − secretion and to enhance airway surface liquid (ASL). This CFTR-agnostic approach is thought to improve mucociliary clearance and lung function in CF. This could indeed improve ASL, however, mucus release and airway contraction may also be induced by activators of TMEM16A, particularly in inflamed airways of patients with asthma, COPD, or CF. Currently, both activators and inhibitors of TMEM16A are developed and examined in different types of tissues. Here we compare activation and inhibition of endogenous and overexpressed TMEM16A and analyze potential off-target effects. The three well-known blockers benzbromarone, niclosamide, and Ani9 inhibited both TMEM16A and ATP-induced Ca 2+ increase by variable degrees, depending on the cell type. Niclosamide, while blocking Ca 2+ activated TMEM16A, also induced a subtle but significant Ca 2+ store release and inhibited store-operated Ca 2+ influx. Niclosamide, benzbromarone and Ani9 also affected TMEM16F whole cell currents, indicating limited specificity for these inhibitors. The compounds Eact, cinnamaldehyde, and melittin, as well as the phosphatidylinositol diC8-PIP 2 are the reported activators of TMEM16A. However, the compounds were unable to activate endogenous TMEM16A in HT 29 colonic epithelial cells. In contrast, TMEM16A overexpressed in HEK293 cells was potently stimulated by these activators. We speculate that overexpressed TMEM16A might have a better accessibility to intracellular Ca 2+ , which causes spontaneous activity even at basal intracellular Ca 2+ concentrations. Small molecules may therefore potentiate pre-stimulated TMEM16A currents, but may otherwise fail to activate silent endogenous TMEM16A.

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Section: Activators Of Tmem16a Act Differently On Endogenous and Overmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pharmacological Inhibition and Activation of the Ca2+ Activated Cl− Channel TMEM16A

Centeio

Cabrita

Benedetto

et al. 2020

IJMS

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“…However, caution is needed since small molecules are rarely specific for a single target. Since the discovery of TMEM16A as a chloride channel (Caputo et al 2008;Schroeder et al 2008;Yang et al 2008), several inhibitors have been discovered, including CaCCinh-A01 (De La Fuente et al 2008), T16inh-A01 (Namkung et al 2011a), tannic acid (Namkung et al 2010b), MONNA (Oh et al 2013), niclosamide (Miner et al 2019) and Ani9 (Seo et al 2016). The number of activators of TMEM16A is instead much smaller.…”

Section: Discussionmentioning

confidence: 99%

TRPV4 and purinergic receptor signalling pathways are separately linked in airway epithelia to CFTR and TMEM16A chloride channels

Genovese

Borrelli

Venturini

et al. 2019

The Journal of Physiology

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Key points Eact is a putative pharmacological activator of TMEM16A. Eact is strongly effective in recombinant Fischer rat thyroid (FRT) cells but not in airway epithelial cells with endogenous TMEM16A expression. Transcriptomic analysis, gene silencing and functional studies in FRT cells reveal that Eact is actually an activator of the Ca2+‐permeable TRPV4 channel. In airway epithelial cells TRPV4 and TMEM16A are expressed in separate cell types. Intracellular Ca2+ elevation by TRPV4 stimulation leads to CFTR channel activation. Abstract TMEM16A is a Ca2+‐activated Cl− channel expressed in airway epithelial cells, particularly under conditions of mucus hypersecretion. To investigate the role of TMEM16A, we used Eact, a putative TMEM16A pharmacological activator. However, in contrast to purinergic stimulation, we found little effect of Eact on bronchial epithelial cells under conditions of high TMEM16A expression. We hypothesized that Eact is an indirect activator of TMEM16A. By a combination of approaches, including short‐circuit current recordings, bulk and single cell RNA sequencing, intracellular Ca2+ imaging and RNA interference, we found that Eact is actually an activator of the Ca2+‐permeable TRPV4 channel and that the modest effect of this compound in bronchial epithelial cells is due to a separate expression of TMEM16A and TRPV4 in different cell types. Importantly, we found that TRPV4 stimulation induced activation of the CFTR Cl− channel. Our study reveals the existence of separate Ca2+ signalling pathways linked to different Cl− secretory processes.

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“…These roles include the regulation of airway smooth muscle contraction and airway hyper-responsiveness, goblet cell formation and goblet cell exocytosis. TMEM16A expression has been identified in airway smooth muscle [84] and the TMEM16A blockers benzbromarone and niclosamide have been reported to attenuate human and murine airway smooth muscle contraction [52,85,86]. Benzbromarone was also demonstrated to impair mucin release from cultured human airway epithelial cells, suggesting a role for TMEM16A in the mechanism of goblet cell exocytosis [52].…”

Section: Additional Roles For Tmem16a In the Airways: Could Tmem16a Imentioning

confidence: 99%

TMEM16A: An Alternative Approach to Restoring Airway Anion Secretion in Cystic Fibrosis?

Danahay

Gosling

2020

IJMS

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The concept that increasing airway hydration leads to improvements in mucus clearance and lung function in cystic fibrosis has been clinically validated with osmotic agents such as hypertonic saline and more convincingly with cystic fibrosis transmembrane conductance regulator (CFTR) repair therapies. Although rapidly becoming the standard of care in cystic fibrosis (CF), current CFTR modulators do not treat all patients nor do they restore the rate of decline in lung function to normal levels. As such, novel approaches are still required to ensure all with CF have effective therapies. Although CFTR plays a fundamental role in the regulation of fluid secretion across the airway mucosa, there are other ion channels and transporters that represent viable targets for future therapeutics. In this review article we will summarise the current progress with CFTR-independent approaches to restoring mucosal hydration, including epithelial sodium channel (ENaC) blockade and modulators of SLC26A9. A particular emphasis is given to modulation of the airway epithelial calcium-activated chloride channel (CaCC), TMEM16A, as there is controversy regarding whether it should be positively or negatively modulated. This is discussed in light of a recent report describing for the first time bona fide TMEM16A potentiators and their positive effects upon epithelial fluid secretion and mucus clearance.

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Drug Repurposing: The Anthelmintics Niclosamide and Nitazoxanide Are Potent TMEM16A Antagonists That Fully Bronchodilate Airways

Cited by 116 publications

References 112 publications

Pharmacological Inhibition and Activation of the Ca2+ Activated Cl− Channel TMEM16A

Pharmacological Inhibition and Activation of the Ca2+ Activated Cl− Channel TMEM16A

TRPV4 and purinergic receptor signalling pathways are separately linked in airway epithelia to CFTR and TMEM16A chloride channels

TMEM16A: An Alternative Approach to Restoring Airway Anion Secretion in Cystic Fibrosis?

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