Anoctamin 1 (TMEM16A) is essential for testosterone-induced prostate hyperplasia

Protective Effects of Niclosamide Ethanolamine Against Testosterone-Induced Benign Prostatic Hyperplasia in Rats

Benign prostatic hyperplasia is a common urological condition in aging men. The anthelmintic agent niclosamide ethanolamide exhibits a wide range of pharmacological activities. This study aimed to evaluate the protective effect of niclosamide ethanolamide in testosterone propionate-induced benign prostatic hyperplasia in rats along with elucidating the probable mechanism of action by investigating the influence on PPAR-γ and Wnt/β-catenin. 40 male Wistar rats were divided randomly into 4 groups. The healthy (control) group, received daily oral and subcutaneous administration of the vehicle. The Induced (TP) group, received only a daily dose of testosterone propionate 3 mg/kg, SC for 28 days. The treated groups (TP+FIN) and (TP+NE), received a concomitant administration of a daily dose of testosterone propionate along with finasteride 5 mg/kg/day and niclosamide ethanolamide 50 mg/kg/day respectively through oral gavage. Animals were euthanized on day 30 of the experiment and prostate tissue samples were collected to evaluate prostate index, prostate hyperplastic markers by ELISA, and gene expression by RT-qPCR. Results revealed that niclosamide ethanolamide significantly reduced prostate index compared to the induced (TP) group (P<0.0001). The agent nearly normalized BPH markers including 5α-reductase type-2 enzyme, dihydrotestosterone, and PCNA compared to the induced (TP) group (P<0.0001). The agent reduced the tissue level of β-catenin while elevating PPAR-γ to control levels (P<0.05). The current study revealed that NE can help prevent BPH in rats by upregulating the PPAR-γ receptor and inhibiting the Wnt pathway.

The roles and functions of TMEM protein family members in cancers, cardiovascular and kidney diseases (Review)

Transmembrane protein (TMEM) is a type of membrane proteins, encoded by TMEM gene, also known as integral membrane protein. TMEM gene family contains various members and its encoded proteins have various functions and expressed in numerous organs. It has been proved to be widely involved in the formation of a lot of organelle membranes, enzymes, receptors and channels, mediating numerous normal physiological functions and regulating various disease processes. At present, accumulating evidences at home and abroad have shown that TMEM is involved in regulating the occurrence and development of different tumors, cardiovascular and kidney diseases. The improved understanding of molecular mechanisms of TMEM genes and proteins may provide new directions and ideas for the prevention, diagnosis and treatment of diseases. In the present review, the roles of TMEM and biological functions in various cancers, cardiovascular and kidney diseases were discussed.

The emerging role of transmembrane proteins in tumorigenesis and therapy

Transmembrane proteins (TMEMs) are a kind of proteins that can cross the phospholipid bilayer one or multiple times and remain permanently anchored. They are involved in the regulation of many biological functions, and their dysregulation is associated with many human diseases and even cancer. Abnormal expression alterations of TMEMs widely exist in tumor tissues compared with paracancerous tissues. They are associated with the clinicopathological features of cancer patients by promoting or inhibiting the development of cancer, thus affecting survival. This review summarized the structure and physiological functions of TMEMs, as well as their roles in tumorigenesis, such as cell proliferation, apoptosis, autophagy, adhesion, metastasis, metabolism and drug resistance. In addition, we elaborated on the potentiality of TMEMs for tumor immunity. Moreover, the advances of TMEMs were subsequently retrospected in several common types of human cancers, including breast cancer, gastric cancer, and lung cancer. Subsequently, we outlined the targeted therapeutic strategies against TMEMs proposed based on existing studies. To date, there are still many TMEMs whose functions and mechanisms have not been well known due to their special structures. Since the important roles TMEMs plays in the development of human cancers, it is urgent to portray their structure and function in carcinogenesis, providing potential biomarkers for cancer patients in the future.

Purple corn extract improves benign prostatic hyperplasia by inhibiting 5 alpha-reductase type 2 and inflammation in testosterone propionate-induced rats

Benign prostatic hyperplasia (BPH) is a health issue caused by an enlarged prostate in older men. Its prevalence increases with age, and it results in urination-related problems. This works studied the effect of purple corn extract (PCE) on improving BPH symptoms using a testosterone propionate (TP)-induced rat model. PCE reduced the enlargement and weight of the prostate through the inhibition of the conversion of testosterone to dihydrotestosterone (DHT) by inhibiting 5α-reductase type 2 (Srd5a2) in TP-induced BPH rats. In these rats, PCE decreased androgen receptor (AR) expression, AR-mediated signaling, and cell proliferation and increased apoptotic cell death. Finally, PCE exhibited anti-inflammatory activity through the regulation of the nuclear factor-kappa B (NF-κB) and nuclear factor erythroid 2-related factor 2 (Nrf-2) axis. These results indicate that the Srd5a2 inhibition and anti-inflammatory activity are some of the beneficial effects of PCE that improve BPH symptoms.

Anticancer Effect of Hemin through ANO1 Inhibition in Human Prostate Cancer Cells

Anoctamin1 (ANO1), a calcium-activated chloride channel, is overexpressed in a variety of cancer cells, including prostate cancer, and is involved in cancer cell proliferation, migration, and invasion. Inhibition of ANO1 in these cancer cells exhibits anticancer effects. In this study, we conducted a screening to identify novel ANO1 inhibitors with anticancer effects using PC-3 human prostate carcinoma cells. Screening of 2978 approved and investigational drugs revealed that hemin is a novel ANO1 inhibitor with an IC50 value of 0.45 μM. Notably, hemin had no significant effect on intracellular calcium signaling and cystic fibrosis transmembrane conductance regulator (CFTR), a cyclic AMP (cAMP)-regulated chloride channel, and it showed a weak inhibitory effect on ANO2 at 3 μM, a concentration that completely inhibits ANO1. Interestingly, hemin also significantly decreased ANO1 protein levels and strongly inhibited the cell proliferation and migration of PC-3 cells in an ANO1-dependent manner. Furthermore, it strongly induced caspase-3 activation, PARP degradation, and apoptosis in PC-3 cells. These findings suggest that hemin possesses anticancer properties via ANO1 inhibition and could be considered for development as a novel treatment for prostate cancer.

Function and Regulation of the Calcium-Activated Chloride Channel Anoctamin 1 (TMEM16A)

Various human tissues express the calcium-activated chloride channel Anoctamin 1 (ANO1), also known as TMEM16A. ANO1 allows the passive chloride flux that controls different physiological functions ranging from muscle contraction, fluid and hormone secretion, gastrointestinal motility, and electrical excitability. Overexpression of ANO1 is associated with pathological conditions such as hypertension and cancer. The molecular cloning of ANO1 has led to a surge in structural, functional, and physiological studies of the channel in several tissues. ANO1 is a homodimer channel harboring two pores - one in each monomer - that work independently. Each pore is activated by voltage-dependent binding of two intracellular calcium ions to a high-affinity-binding site. In addition, the binding of phosphatidylinositol 4,5-bisphosphate to sites scattered throughout the cytosolic side of the protein aids the calcium activation process. Furthermore, many pharmacological studies have established ANO1 as a target of promising compounds that could treat several illnesses. This chapter describes our current understanding of the physiological roles of ANO1 and its regulation under physiological conditions as well as new pharmacological compounds with potential therapeutic applications.

TMEM16A partners with mTOR to influence pathways of cell survival, proliferation, and migration in cholangiocarcinoma

Expression of transmembrane protein 16 A (TMEM16A), a calcium activated chloride channel, is elevated in some human cancers and impacts tumor cell proliferation, metastasis, and patient outcome. Evidence presented here uncovers a molecular synergy between TMEM16A and mechanistic/mammalian target of rapamycin (mTOR), a serine-threonine kinase that is known to promote cell survival and proliferation in cholangiocarcinoma (CCA), a lethal cancer of the secretory cells of bile ducts. Analysis of gene and protein expression in human CCA tissue and CCA cell line detected elevated TMEM16A expression and Cl- channel activity. The Cl- channel activity of TMEM16A impacted the actin cytoskeleton and the ability of cells to survive, proliferate, and migrate as revealed by pharmacological inhibition studies. The basal activity of mTOR, too, was elevated in the CCA cell line compared with the normal cholangiocytes. Molecular inhibition studies provided further evidence that TMEM16A and mTOR were each able to influence the regulation of the other's activity or expression respectively. Consistent with this reciprocal regulation, combined TMEM16A and mTOR inhibition produced a greater loss of CCA cell survival and migration than their individual inhibition alone. Together these data reveal that the aberrant TMEM16A expression and cooperation with mTOR contribute to a certain advantage in CCA.NEW & NOTEWORTHY This study points to the dysregulation of transmembrane protein 16 A (TMEM16A) expression and activity in cholangiocarcinoma (CCA), the inhibition of which has functional consequences. Dysregulated TMEM16A exerts an influence on the regulation of mechanistic/mammalian target of rapamycin (mTOR) activity. Moreover, the reciprocal regulation of TMEM16A by mTOR demonstrates a novel connection between these two protein families. These findings support a model in which TMEM16A intersects the mTOR pathway to regulate cell cytoskeleton, survival, proliferation, and migration in CCA.

Role of Sex Hormones in Prevalent Kidney Diseases

Chronic kidney disease (CKD) is a constantly growing global health burden, with more than 840 million people affected worldwide. CKD presents sex disparities in the pathophysiology of the disease, as well as in the epidemiology, clinical manifestations, and disease progression. Overall, while CKD is more frequent in females, males have a higher risk to progress to end-stage kidney disease. In recent years, numerous studies have highlighted the role of sex hormones in the health and diseases of several organs, including the kidney. In this review, we present a clinical overview of the sex-differences in CKD and a selection of prominent kidney diseases causing CKD: lupus nephritis, diabetic kidney disease, IgA nephropathy, and autosomal dominant polycystic kidney disease. We report clinical and experimental findings on the role of sex hormones in the development of the disease and its progression to end-stage kidney disease.

TRPV3-ANO1 interaction positively regulates wound healing in keratinocytes

Transient receptor potential vanilloid 3 (TRPV3) belongs to the TRP ion channel super family and functions as a nonselective cation channel that is highly permeable to calcium. This channel is strongly expressed in skin keratinocytes and is involved in warmth sensation, itch, wound healing and secretion of several cytokines. Previous studies showed that anoctamin1 (ANO1), a calcium-activated chloride channel, was activated by calcium influx through TRPV1, TRPV4 or TRPA1 and that these channel interactions were important for TRP channel-mediated physiological functions. We found that ANO1 was expressed by normal human epidermal keratinocytes (NHEKs). We observed that ANO1 mediated currents upon TRPV3 activation of NHEKs and mouse skin keratinocytes. Using an in vitro wound-healing assay, we observed that either a TRPV3 blocker, an ANO1 blocker or low chloride medium inhibited cell migration and proliferation through p38 phosphorylation, leading to cell cycle arrest. These results indicated that chloride influx through ANO1 activity enhanced wound healing by keratinocytes.

Hepatocyte-specific TMEM16A deficiency alleviates hepatic ischemia/reperfusion injury via suppressing GPX4-mediated ferroptosis

Ischemia/reperfusion (I/R)-induced liver injury with severe cell death is a major complication of liver transplantation. Transmembrane member 16A (TMEM16A), a component of hepatocyte Ca²⁺-activated chloride channel, has been implicated in a variety of liver diseases. However, its role in hepatic I/R injury remains unknown. Here, mice with hepatocyte-specific TMEM16A knockout or overexpression were generated to examine the effect of TMEM16A on hepatic I/R injury. TMEM16A expression increased in liver samples from patients and mice with I/R injury, which was correlated with liver damage progression. Hepatocyte-specific TMEM16A knockout alleviated I/R-induced liver damage in mice, ameliorating inflammation and ferroptotic cell death. However, mice with hepatic TMEM16A overexpression showed the opposite phenotype. In addition, TMEM16A ablation decreased inflammatory responses and ferroptosis in hepatocytes upon hypoxia/reoxygenation insult in vitro, whereas TMEM16A overexpression promoted the opposite effects. The ameliorating effects of TMEM16A knockout on hepatocyte inflammation and cell death were abolished by chemically induced ferroptosis, whereas chemical inhibition of ferroptosis reversed the potentiated role of TMEM16A in hepatocyte injury. Mechanistically, TMEM16A interacted with glutathione peroxidase 4 (GPX4) to induce its ubiquitination and degradation, thereby enhancing ferroptosis. Disruption of TMEM16A-GPX4 interaction abrogated the effects of TMEM16A on GPX4 ubiquitination, ferroptosis, and hepatic I/R injury. Our results demonstrate that TMEM16A exacerbates hepatic I/R injury by promoting GPX4-dependent ferroptosis. TMEM16A-GPX4 interaction and GPX4 ubiquitination are therefore indispensable for TMEM16A-regulated hepatic I/R injury, suggesting that blockades of TMEM16A-GPX4 interaction or TMEM16A inhibition in hepatocytes may represent promising therapeutic strategies for acute liver injury.

Cordycepin Attenuates Testosterone-Induced Benign Prostatic Hyperplasia in Rats via Modulation of AMPK and AKT Activation

Benign prostatic hyperplasia (BPH) is a disease that commonly affects elderly men. Cordycepin is an adenosine analog with a wide range of pharmacological activities including antiproliferative and prostatic smooth muscle relaxant effects. This study was designed to assess the actions of cordycepin in testosterone-induced BPH in rats. Animals were divided into six treatment groups: control, cordycepin-alone (10 mg/kg), testosterone-alone (3 mg/kg), cordycepin (5 mg/kg) + testosterone, cordycepin (10 mg/kg) + testosterone, and finasteride (0.5 mg/kg) + testosterone. Treatments were continued daily, 5 days a week, for 4 weeks. Cordycepin significantly prevented the increase in prostate weight and prostate index induced by testosterone. This was confirmed by histopathological examinations. Cordycepin antiproliferative activity was further defined by its ability to inhibit cyclin-D1 and proliferating cell nuclear antigen (PCNA) expression. In addition, cordycepin exhibited significant antioxidant properties as proven by the prevention of lipid peroxidation, reduced glutathione diminution, and superoxide dismutase exhaustion. This was paralleled by anti-inflammatory activity as shown by the inhibition of interleukin-6, tumor necrosis factor-α, and nuclear factor-κB expression in prostatic tissues. It also enhanced apoptosis as demonstrated by its ability to enhance and inhibit mRNA expression of Bax and Bcl2, respectively. Western blot analysis indicated that cordycepin augmented phospho-AMP-activated protein kinase (p-AMPK) and inhibited p-AKT expression. Collectively, cordycepin has the ability to prevent testosterone-induced BPH in rats. This is mediated, at least partially, by its antiproliferative, antioxidant, anti-inflammatory, and pro-apoptotic actions in addition to its modulation of AMPK and AKT activation.

ANO1: More Than Just Calcium-Activated Chloride Channel in Cancer

ANO1, a calcium-activated chloride channel (CACC), is also known as transmembrane protein 16A (TMEM16A). It plays a vital role in the occurrence, development, metastasis, proliferation, and apoptosis of various malignant tumors. This article reviews the mechanism of ANO1 involved in the replication, proliferation, invasion and apoptosis of various malignant tumors. Various molecules and Stimuli control the expression of ANO1, and the regulatory mechanism of ANO1 is different in tumor cells. To explore the mechanism of ANO1 overexpression and activation of tumor cells by studying the different effects of ANO1. Current studies have shown that ANO1 expression is controlled by 11q13 gene amplification and may also exert cell-specific effects through its interconnected protein network, phosphorylation of different kinases, and signaling pathways. At the same time, ANO1 also resists tumor apoptosis and promotes tumor immune escape. ANO1 can be used as a promising biomarker for detecting certain malignant tumors. Further studies on the channels and the mechanism of protein activity of ANO1 are needed. Finally, the latest inhibitors of ANO1 are summarized, which provides the research direction for the tumor-promoting mechanism of ANO1.

Purple Corn Extract Improves Benign Prostatic Hyperplasia by Regulating Prostate Cell Proliferation and Apoptosis

Purple corn (Zea mays L.), utilized as a natural pigment in food production and processing, has been used to treat obesity, cystitis, and urinary tract infections. However, no reports of its use for benign prostatic hyperplasia (BPH) exist. Purple corn extract (PCE) contains anthocyanins, particularly cyanidin-3-O-glucoside, which have various pharmacological characteristics. Therefore, this study sought to elucidate the ameliorative effect of PCE on BPH in dihydrotestosterone (DHT)-stimulated WPMY-1 cells and testosterone propionate (TP)-induced rats. Expression levels of the upregulated androgen receptor (AR) and its related genes in DHT-stimulated WPMY-1 cells were reduced by PCE, and proapoptotic gene expression increased by modulating the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling cascade. PCE reduced the weight of the enlarged prostate by inhibiting the androgen/AR signaling-related markers. Histological variations in the prostate epithelium caused by TP injection were restored by PCE. Thus, PCE alleviates BPH by modulating prostate cell proliferation and apoptosis.

Role of ANO1 in tumors and tumor immunity

Dysregulation of gene amplification, cell-signaling-pathway transduction, epigenetic and transcriptional regulation, and protein interactions drives tumor-cell proliferation and invasion, while ion channels also play an important role in the generation and development of tumor cells. Overexpression of Ca²⁺-activated Cl- channel anoctamin 1 (ANO1) is shown in numerous cancer types and correlates with poor prognosis. However, the mechanisms involved in ANO1-mediated malignant cellular transformation and the role of ANO1 in tumor immunity remain unknown. In this review, we discuss recent studies to determine the role of ANO1 in tumorigenesis and provide novel insights into the role of ANO1 in the context of tumor immunity. Furthermore, we analyze the roles and potential mechanisms of ANO1 in different types of cancers, and provide novel notions for the role of ANO1 in the tumor microenvironment and for potential use of ANO1 in clinical applications. Our review shows that ANO1 is involved in tumor immunity and microenvironment, and may, therefore, be an effective biomarker and therapeutic drug target.

Blockade of TMEM16A protects against renal fibrosis by reducing intracellular Cl- concentration

BACKGROUND AND PURPOSE

Renal fibrosis is the final common outcome in most forms of CKD. However, the underlying causal mechanisms remain obscure. The present study examined whether TMEM16A, a Ca²⁺ -activated chloride channel, contributes to the progress of renal fibrosis.

EXPERIMENTAL APPROACH

Masson staining, western blot and immunohistochemistry were used to measure renal fibrosis and related proteins expression. MQAE was used to evaluate the intracellular Cl^- concentration.

KEY RESULTS

TMEM16A expression was significantly upregulated in fibrotic kidneys of unilateral ureteral obstruction (UUO) and high-fat diet murine models, and in renal samples of IgA nephropathy patients. In vivo knockdown of TMEM16A with adenovirus harboring TMEM16A-shRNA or inhibition of TMEM16A channel activity with its specific inhibitor CaCCinh-A01 or T16Ainh-A01 effectively prevented UUO-induced renal fibrosis and decreased protein expression of fibronectin, α-SMA and collagen in the obstructed kidneys. In cultured HK2 cells, knockdown or inhibition of TMEM16A suppressed TGF-β1-induced epithelial to mesenchymal transition, reduced snail1 expression and phosphorylation of Smad2/3 and ERK1/2, whereas overexpression of TMEM16A showed the opposite effects. TGF-β1 increased [Cl^- ]i in HK2 cells, which was inhibited by knockdown or inhibition of TMEM16A. Reducing [Cl^- ]i by low Cl^- culture medium significantly blunted TGF-β1-induced Smad2/3 phosphorylation and profibrotic factors expression. The profibrotic effects of TGF-β1 were also abrogated by the inhibitor of SGK1, a kinase whose activity was also suppressed by reducing [Cl^- ]i.

CONCLUSION AND IMPLICATIONS

Blockade of TMEM16A prevented the progression of kidney fibrosis, likely by suppressing [Cl^- ]i/SGK1/TGF-β1 signaling pathway. TMEM16A may be a potential new therapeutic target against renal fibrosis.

Dihydroartemisinin attenuates benign prostatic hyperplasia in rats by inhibiting prostatic epithelial cell proliferation

Background

Benign prostatic hyperplasia (BPH) is a common urological condition in aging men. While dihydroartemisinin (DHA) exhibits a wide range of pharmacological activities, to date, there have been no studies examining the effects of DHA on BPH.

Methods

An in vivo BPH model was constructed in rats via daily subcutaneous injection of testosterone propionate (TP) for 28 consecutive days. Rats were randomly distributed into four groups and treated as follows: (I) control; (II) TP treatment; (III) TP and finasteride treatment (positive control); and (IV) TP and DHA treatment. At the end of the experiment, rats were sacrificed and the prostate weight, prostate index, thickness of the epithelium, collagen deposition, serum dihydrotestosterone (DHT) levels, 5α-reductase 2 (5AR-2) expression, and proliferating cell nuclear antigen (PCNA) levels in the prostate were examined. Normal human prostatic epithelial RWPE-1 cells were used in in vitro experiments to further investigate the anti-proliferative effects of DHA.

Results

TP increased the prostate weight and prostate index in rats, and this effect was reduced with DHA treatment. In addition, DHA attenuated the morphological changes and collagen deposition in the prostate tissue induced by TP. Furthermore, DHA reduced the expression of PCNA, serum DHT, and prostatic 5AR-2 in rats with TP-induced BPH. In vitro analysis revealed that DHA significantly inhibited the proliferation of TP-treated RWPE-1 cells.

Conclusions

DHA significantly inhibited the development of BPH by suppressing serum DHT levels, prostatic 5AR-2 expression, and the proliferation of benign prostatic epithelial cells. Thus, DHA is a novel medicinal agent with potential therapeutic efficacy in the treatment of patients with BPH.

Anoctamin1 Induces Hyperproliferation of HaCaT Keratinocytes and Triggers Imiquimod-Induced Psoriasis-Like Skin Injury in Mice

Psoriasis, a long-lasting and multifactorial skin disease, is related to comorbidities such as metabolic disease, depression, and psoriatic arthritis. Psoriasis occurs due to a variety of factors including keratinocyte hyperproliferation, inflammation, and abnormal differentiation. Proinflammatory cytokines upregulated by increased activation of keratinocytes and immune cells in the skin trigger progression of psoriasis. This study aimed to investigate the effects of anoctamin1 (ANO1) on psoriasis development in vitro and in vivo. We analyzed the proliferation of HaCaT keratinocytes and ANO1-related ERK and AKT signaling pathways after ANO1 inhibitor (T16Ainh-A01 and Ani9) treatment and knock-down of ANO1. Furthermore, after applying imiquimod (IMQ) cream or coapplying IMQ cream and T16Ainh-A01 on mouse ears, we not only observed psoriatic symptoms, including ear thickening, but also quantified the effects of treatment on ERK and AKT signaling-involved proteins and proinflammatory cytokines. Inhibition of ANO1 attenuated the proliferation of HaCaT cells and induced reduction of pERK1/2. Coapplication of IMQ and T16Ainh-A01 on ears of mice reduced not only symptoms of IMQ-induced psoriasis such as thickening and erythema, but also expression of ANO1 and pERK1/2 compared to that of application of IMQ alone. In addition, the expression levels of IL-17A, IL-17F, IL-22, IL-23, IL-6, IL-1β, and TNF-α increased after applying IMQ and were significantly reduced by coapplying IMQ and T16Ainh-A01. These results aid in understanding the underlying mechanisms of ANO1 in epidermal layer keratinocyte hyperproliferation and suggest the potential of ANO1 as a target to treat psoriasis.

Gender-Dependent Phenotype in Polycystic Kidney Disease Is Determined by Differential Intracellular Ca2+ Signals

Autosomal dominant polycystic kidney disease (ADPKD) is caused by loss of function of PKD1 (polycystin 1) or PKD2 (polycystin 2). The Ca²⁺-activated Cl⁻ channel TMEM16A has a central role in ADPKD. Expression and function of TMEM16A is upregulated in ADPKD which causes enhanced intracellular Ca²⁺ signaling, cell proliferation, and ion secretion. We analyzed kidneys from Pkd1 knockout mice and found a more pronounced phenotype in males compared to females, despite similar levels of expression for renal tubular TMEM16A. Cell proliferation, which is known to be enhanced with loss of Pkd1^−/−, was larger in male when compared to female Pkd1^−/− cells. This was paralleled by higher basal intracellular Ca²⁺ concentrations in primary renal epithelial cells isolated from Pkd1^−/− males. The results suggest enhanced intracellular Ca²⁺ levels contributing to augmented cell proliferation and cyst development in male kidneys. Enhanced resting Ca²⁺ also caused larger basal chloride currents in male primary cells, as detected in patch clamp recordings. Incubation of mouse primary cells, mCCDcl1 collecting duct cells or M1 collecting duct cells with dihydrotestosterone (DHT) enhanced basal Ca²⁺ levels and increased basal and ATP-stimulated TMEM16A chloride currents. Taken together, the more severe cystic phenotype in males is likely to be caused by enhanced cell proliferation, possibly due to enhanced basal and ATP-induced intracellular Ca²⁺ levels, leading to enhanced TMEM16A currents. Augmented Ca²⁺ signaling is possibly due to enhanced expression of Ca²⁺ transporting/regulating proteins.

The Ca2+-activated chloride channel ANO1/TMEM16A: An emerging therapeutic target for epithelium-originated diseases?

Anoctamin 1 (ANO1) or TMEM16A gene encodes a member of Ca²⁺ activated Cl^– channels (CaCCs) that are critical for physiological functions, such as epithelial secretion, smooth muscle contraction and sensory signal transduction. The attraction and interest in ANO1/TMEM16A arise from a decade long investigations that abnormal expression or dysfunction of ANO1 is involved in many pathological phenotypes and diseases, including asthma, neuropathic pain, hypertension and cancer. However, the lack of specific modulators of ANO1 has impeded the efforts to validate ANO1 as a therapeutic target. This review focuses on the recent progress made in understanding of the pathophysiological functions of CaCC ANO1 and the current modulators used as pharmacological tools, hopefully illustrating a broad spectrum of ANO1 channelopathy and a path forward for this target validation.

Opposing roles of E3 ligases TRIM23 and TRIM21 in regulation of ion channel ANO1 protein levels

Anoctamin-1 (ANO1) (TMEM16A) is a calcium-activated chloride channel that plays critical roles in diverse physiological processes, such as sensory transduction and epithelial secretion. ANO1 levels have been shown to be altered under physiological and pathological conditions, although the molecular mechanisms that control ANO1 protein levels remain unclear. The ubiquitin–proteasome system is known to regulate the levels of numerous ion channels, but little information is available regarding whether and how ubiquitination regulates levels of ANO1. Here, we showed that two E3 ligases, TRIM23 and TRIM21, physically interact with the C terminus of ANO1. In vitro and in vivo assays demonstrated that whereas TRIM23 ubiquitinated ANO1 leading to its stabilization, TRIM21 ubiquitinated ANO1 and induced its degradation. Notably, ANO1 regulation by TRIM23 and TRIM21 is involved in chemical-induced pain sensation, salivary secretion, and heart-rate control in mice, and TRIM23 also mediates ANO1 upregulation induced by epidermal growth factor treatment. Our results suggest that these two antagonistic E3 ligases act together to control ANO1 expression and function. Our findings reveal a previously unrecognized mechanism for regulating ANO1 protein levels and identify a potential molecular link between ANO1 regulation, epidermal growth factor, and other signaling pathways.

Simvastatin inhibits oral squamous cell carcinoma by targeting TMEM16A Ca2+-activated chloride channel

PURPOSE

Ca²⁺-activated chloride channel TMEM16A has been found to be overexpressed in many cancers including head and neck squamous cell carcinoma (HNSCC). Nevertheless, the role of TMEM16A in oral squamous cell carcinoma (OSCC) remains unclear. Although simvastatin is known to produce anti-tumor effect, the mechanisms by which simvastatin inhibits cancer remain unclear.

METHODS

In this study, we explored the role of TMEM16A expression in human OSCC tissues using both TCGA dataset and immunohistochemistry. CCK-8 assay was applied to evaluate cell proliferation. Patch clamp technique was applied to record TMEM16A Cl^- currents.

RESULTS

We found that high TMEM16A expression is related with large tumor size, lymph node metastasis, and poor clinical outcome in patients with OSCC. In addition, TMEM16A overexpression could promote cell proliferation, and inhibition of TMEM16A channel activities could suppress cell proliferation in OSCC cells. Furthermore, simvastatin could suppress TMEM16A channel activities, and inhibited cell proliferation in OSCC cells via TMEM16A.

CONCLUSION

Our findings identify a novel anti-tumor mechanism of simvastatin by targeting TMEM16A. Simvastatin may represent an innovative strategy for treating OSCC with high TMEM16A expression.

Role of Ano1 Ca2+-activated Cl- channels in generating urethral tone

Urinary continence is maintained in the lower urinary tract by the contracture of urethral sphincters, including smooth muscle of the internal urethral sphincter. These contractions occlude the urethral lumen, preventing urine leakage from the bladder to the exterior. Over the past 20 years, research on the ionic conductances that contribute to urethral smooth muscle contractility has greatly accelerated. A debate has emerged over the role of interstitial cell of Cajal (ICC)-like cells in the urethra and their expression of Ca²⁺-activated Cl^- channels encoded by anoctamin-1 [Ano1; transmembrane member 16 A (Tmem16a) gene]. It has been proposed that Ano1 channels expressed in urethral ICC serve as a source of depolarization for smooth muscle cells, increasing their excitability and contributing to tone. Although a clear role for Ano1 channels expressed in ICC is evident in other smooth muscle organs, such as the gastrointestinal tract, the role of these channels in the urethra is unclear, owing to differences in the species (rabbit, rat, guinea pig, sheep, and mouse) examined and experimental approaches by different groups. The importance of clarifying this situation is evident as effective targeting of Ano1 channels may lead to new treatments for urinary incontinence. In this review, we summarize the key findings from different species on the role of ICC and Ano1 channels in urethral contractility. Finally, we outline proposals for clarifying this controversial and important topic by addressing how cell-specific optogenetic and inducible cell-specific genetic deletion strategies coupled with advances in Ano1 channel pharmacology may clarify this area in future studies.NEW & NOTEWORTHY Studies from the rabbit have shown that anoctamin-1 (Ano1) channels expressed in urethral interstitial cells of Cajal (ICC) serve as a source of depolarization for smooth muscle cells, increasing excitability and tone. However, the role of urethral Ano1 channels is unclear, owing to differences in the species examined and experimental approaches. We summarize findings from different species on the role of urethral ICC and Ano1 channels in urethral contractility and outline proposals for clarifying this topic using cell-specific optogenetic approaches.

Efficacy and Safety Evaluation of Transurethral Resection of the Prostate versus Plasmakinetic Enucleation of the Prostate in the Treatment of Massive Benign Prostatic Hyperplasia

BACKGROUND

Benign prostatic hyperplasia (BPH) is a common chronic progressive disease resulting in urinary obstruction in aging men. It comes to more and more patients with massive BPH with the aging of society and extension of life expectancy.

OBJECTIVE

The aim of the study was to compare the clinical efficacy, safety, and complications between transurethral bipolar plasmakinetic enucleation of the prostate (PKEP) and transurethral resection of the prostate (TURP) in the treatment of massive BPH.

DESIGN AND SETTING

Patients with BPH were divided into the PKEP group and the TURP group randomly. Intraoperative blood loss (BL), operation time (OT), resected tissue weight (RTW), gland resection ratio (GRR), postoperative indwelling ureter time (IUT), bladder fistula time (BFT) and hospital stay time (HST), preoperative and postoperative serum sodium concentration (SSC), hemoglobin concentration (HGB), prostate weight (PW), postvoid residual (PVR), maximum urinary flow rate (Qmax), international prostate symptom score (IPSS), quality of life (QOL), International Index of Erectile Function (IIEF), and other complications were analyzed and compared respectively.

RESULTS

There was no statistical difference in preoperative IPSS, preoperative QOL score, preoperative PVR, preoperative Qmax, postoperative QOL score, postoperative PVR, postoperative Qmax, IPSS difference value (DV), Qmax DV, and PVR DV between the PKEP group and the TURP group (p > 0.05). OT, BL, IUT, BFT, HST, and postoperative IPSS in the PKEP group were significantly lower than that in the TURP group (p < 0.01). RTW and GRR in the PKEP group were significantly higher than that in the TURP group (p < 0.01). QOL DV in the PKEP group was higher than that in the TURP group (p < 0.05). There was statistical difference in SSC DV between the PKEP group and the TURP group (p < 0.05). There was significant statistical difference in postoperative PW, postoperative HGB, PW DV, and HGB DV between the PKEP group and the TURP group (p < 0.01). There was significant statistical difference in IPSS, QOL, PVR, and Qmax between postoperative value and preoperative value in both groups (p < 0.01). The incidence of transurethral resection syndrome, obturator nerve reflex, transient urinary incontinence, and retrograde ejaculation between the PKEP group and the TURP group has no statistical difference (p > 0.05). Capsule perforation, blood transfusion, secondary hemorrhage, bladder neck contracture, and urethral stricture in the PKEP group were lower than that in the TURP group (p < 0.05). Bladder spasm in the PKEP group was significantly lower than that in the TURP group (p < 0.01). There was no statistical difference in preoperative and postoperative IIEF-5, effective erectile frequency, telotism average tension, sustainable telotism average time, and sexual dissatisfaction between the PKEP group and the TURP group (p > 0.05).

CONCLUSIONS

PKEP and TURP have similar clinical efficacy in the treatment of massive BPH. PKEP has advantages in shorter OT, less BL, more GRR, and fewer complications, but the long-term therapeutic effect of PKEP needs further follow-up.

Design of Anticancer 2,4-Diaminopyrimidines as Novel Anoctamin 1 (ANO1) Ion Channel Blockers

Pyrimidine is a privileged scaffold in many synthetic compounds exhibiting diverse pharmacological activities, and is used for therapeutic applications in a broad spectrum of human diseases. In this study, we prepared a small set of pyrimidine libraries based on the structure of two hit compounds that were identified through the screening of an in-house library in order to identify an inhibitor of anoctamin 1 (ANO1). ANO1 is amplified in various types of human malignant tumors, such as head and neck, parathyroid, and gastrointestinal stromal tumors, as well as in breast, lung, and prostate cancers. After initial screening and further structure optimization, we identified Aa3 as a dose-dependent ANO1 blocker. This compound exhibited more potent anti-cancer activity in the NCI-H460 cell line, expressing high levels of ANO1 compared with that in A549 cells that express low levels of ANO1. Our results open a new direction for the development of small-molecule ANO1 blockers composed of a pyrimidine scaffold and a nitrogen-containing heterocyclic moiety, with drug-like properties.

Ca2+-activated Cl- channel TMEM16A inhibition by cholesterol promotes angiogenesis in endothelial cells

Introduction

Ca²⁺-activated Cl^- channel TMEM16A is expressed in endothelial cells, and contributes to many diseases such as hypertension, blood-brain barrier dysfunction, and pulmonary hypertension. It remains unclear whether TMEM16A regulates endothelial angiogenesis, which participates in many physiological and pathological processes. Cholesterol regulates many ion channels including TMEM16A, and high cholesterol levels contribute to endothelial dysfunction. It remains to be determined whether cholesterol regulates TMEM16A expression and function in endothelial cells.

Objective

This study aimed to investigate whether cholesterol regulated TMEM16A expression and function in endothelial angiogenesis.

Methods

Whole-cell patch clamp techniques were used to record Ca²⁺-activated Cl^- currents in human aortic endothelial cells (HAECs) and HEK293 cells transfected with TMEM16A-overexpressing plasmids. Western blot was used to examine the expression of TMEM16A and DNA methyltransferase 1 (DNMT1) in HAECs. CCK-8 assay, would healing assay, and tube formation assay were used to test endothelial cell proliferation, migration and angiogenesis, respectively.

Results

TMEM16A mediates the Ca²⁺-activated Cl^- channel in HAECs. Cholesterol treatment inhibited TMEM16A expression via upregulation of DNMT1 in HAECs, and the inhibitory effect of cholesterol on TMEM16A expression was blocked by 5-aza, the DNMT1 inhibitor. In addition, direct application of cholesterol inhibited TMEM16A currents in heterologous HEK293 cells with an IC₅₀ of 0.1209 μM. Similarly, cholesterol directly inhibited TMEM16A currents in HAECs. Furthermore, TMEM16A knockdown increased in vitro tube formation, cell migration and proliferation of HAECs, and TMEM16A overexpression produced the opposite effect.

Conclusion

This study reveals a novel mechanism of cholesterol-mediated TMEM16A inhibition, by which cholesterol reduces TMEM16A expression via DNMT1-mediated methylation and directly inhibits channel activities. TMEM16A channel inhibition promotes endothelial cell angiogenesis.

Altered anoctamin-1 and tyrosine phosphorylation in congenital ureteropelvic junction obstruction

PURPOSE

Ureteropelvic junction (UPJ) obstruction is the most common cause of congenital hydronephrosis in children. The pathophysiology of UPJ obstruction and the exact mechanism of pelviureteral peristalsis are poorly understood. Anoctamin-1 (ANO1), a Ca²⁺-activated chloride channel, has been shown to play a key role in muscle wall contractions in the gastrointestinal tract. We designed this study to investigate the hypothesis that ANO1 is expressed in smooth muscle cells (SMCs) of the human UPJ and that tyrosine phosphorylation is altered in UPJ obstruction.

MATERIALS AND METHODS

Fresh frozen specimens of UPJ obstruction (n = 28) and control specimens from patients who underwent Wilms' tumor nephrectomy (n = 20) were prepared. Western blot (WB) was performed to evaluate levels of ANO1 protein expression and changes in tyrosine phosphorylation. In addition analysis of ANO1 and phalloidin using confocal-immunofluoresence-double staining and 3D reconstruction were carried out.

RESULTS

Our WB results revealed increased tyrosine phosphorylation in UPJ obstruction samples compared to controls, and decreased ANO1 expression in UPJ obstruction. Confocal microscopy showed that ANO1 immunoreactivity was decreased in SMCs of UPJ obstruction compared to controls.

CONCLUSIONS

We provide evidence, for the first time, of the presence of ANO1 expression in the human UPJ. We speculate that altered tyrosine phosphorylation, observed in UPJ obstruction, may lead to a failure of transmission of peristaltic waves in UPJ obstruction by inhibiting Ca²⁺-activated chloride channels in SMCs.

Oral exposure to low-dose bisphenol A induces hyperplasia of dorsolateral prostate and upregulates EGFR expression in adult Sprague-Dawley rats

Prostate is sensitive to endocrine hormone level, and the synergetic effect of estrogen and androgen is critical in prostate growth. The change of signal pathways caused by the imbalance of estrogen and androgen might function in the occurrence of prostate diseases. As a well-known endocrine disruptor compound, bisphenol A (BPA) can disturb the normal function of endocrine hormone and affect prostate development. This study aims to investigate effects of BPA on the dorsolateral prostate (DLP) and the related gene expression of the tissue in adult Sprague-Dawley (SD) rats and to explore the mechanism for the effect of low-dose BPA on DLP hyperplasia. Three-month-old male SD rats were treated with BPA (10.0, 30.0, or 90.0 µg (kg.day)^-1, gavage) or vehicle (gavage) for 4 weeks. BPA significantly increased the DLP weight, the DLP organ coefficient, and the prostate epithelium height (p < 0.01) of rats dose-dependently. Microarray analysis and quantitative real-time polymerase chain reaction showed that BPA significantly upregulated the transcriptional levels of some genes, including pituitary tumor transforming gene 1, epidermal growth factor, Sh3kbp1, and Pcna. Furthermore, the expression of PCNA (p < 0.01), androgen receptor (p < 0.01), and EGF receptor (EGFR) (p < 0.001) in DLP was increased significantly by BPA treatment, and the expression of estrogen receptor alpha was also upregulated. The findings evidenced that low-dose BPA could induce DLP hyperplasia in adult rats, and the upregulated EGF/EGFR pathway that was responsive to estrogen and androgen might play an essential role in the DLP hyperplasia induced by low-dose BPA.

Detection of ANO1 mRNA in PBMCs is a promising method for GISTs diagnosis

ANO1 is a calcium-activated chloride channel protein that has been used to diagnose GISTs after tissue biopsy. Recently, ANO1 mRNA amplification in the blood has received considerable attention as a useful method for the diagnosis of GISTs. The aim of this study was to evaluate the diagnostic ability of ANO1 mRNA in distinguishing GIST patients from healthy subjects. We constructed a logistic regression model for examining the diagnostic ability of ANO1 mRNA in comparison with conventional tumor markers, including CEA, CA199, and CA724. Our results showed that ANO1 mRNA was significantly amplified in PBMCs, the average expression level and range of ANO1 mRNA in the blood were increased along with the expression of ANO1 in the tissues, and the extent of amplification of ANO1 was associated with tumor size. In addition, ROC curve analysis showed that ANO1 mRNA in the blood had the highest specificity when compared with conventional tumor markers. Moreover, a combined analysis with ANO1 mRNA and conventional tumor markers had the highest sensitivity in diagnosing GISTs. Our study indicated that detection of ANO1 mRNA in PBMCs is a promising method for diagnosis of GISTs in vitro.

A mutual activation loop between the Ca2+-activated chloride channel TMEM16A and EGFR/STAT3 signaling promotes breast cancer tumorigenesis

The Ca²⁺-activated chloride channel TMEM16A (anoctamin 1) is overexpressed in breast cancer. It remains unclear how TMEM16A overexpression plays a role in carcinogenesis in breast cancer. In this study, we found that high TMEM16A expression in combination with high EGFR or STAT3 expression was significantly associated with shorter overall survival in ER-positive breast cancer patients without tamoxifen treatment, and longer overall survival in patients with tamoxifen treatment. EGFR/STAT3 signaling activation by EGF promoted TMEM16A expression, and TMEM16A overexpression activated EGFR/STAT3 signaling in breast cancer cells. Both in vitro and in animal studies showed that TMEM16A overexpression promoted, and TMEM16A knockdown inhibited breast cancer cell proliferation and tumor growth. In addition, TMEM16A overexpression-induced cell proliferation was blocked by EGFR/STAT3 inhibitors, and TMEM16A knockdown reduced EGF-induced proliferation and tumorigenesis in breast cancer. Furthermore, inhibition of TMEM16A channel function effectively reduced breast cancer cell proliferation, especially in combination with EGFR inhibitors. Our findings identify a mutual activation loop between TMEM16A and EGFR/STAT3 signaling, which is important for breast cancer proliferation and growth. TMEM16A inhibition may represent a novel therapy for EGFR-expressing breast cancer.

Calcium-activated chloride channel regulator 1 as a prognostic biomarker in pancreatic ductal adenocarcinoma

BACKGROUND

In a previous study utilizing mass spectrometry-based proteomics, we identified calcium-activated chloride channel regulator 1 (CLCA1) as a potential tumor suppressor in pancreatic cancer and the expression was inversely correlated with patient survival. The aim of the study was to further validate the prognostic significance of CLCA1 in pancreatic cancer.

METHODS

CLCA1 expression was evaluated with tissue microarrays and immunohistochemistry in 140 patients with pancreatic ductal adenocarcinoma that underwent surgical resection at Skåne University Hospital, Sweden. Kaplan-Meier and Cox proportional hazards modeling were used to explore the association between CLCA1 and clinicopathological factors and survival.

RESULTS

CLCA1 expression was denoted as positive in 90 tumors (64.3%), with positive staining being limited to the tumor cells. There were no significant association between CLCA1 expression and established clinicopathological parameters. Low CLCA1 expression correlated significantly with shorter disease-free survival (11.9 vs 17.5 months, P = 0.042). Multivariable Cox regression analysis confirmed the results (HR 0.61, 95% CI-0.40-0.92, P = 0.019).

CONCLUSIONS

Low CLCA1 expression is an independent factor of poor disease-free survival in pancreatic cancer.

Tissue-specific variation in 5'-terminal exons of mouse Anoctamin 1 transcript induces N-terminal variation of its protein via alternative translational start sites

Anoctamin 1 (encoded by the Ano1 gene) is a Ca²⁺-activated Cl^- channel critical to many physiological functions. It has been speculated that Ano1 expression is regulated in a tissue-dependent manner via alternative promoters. However, variation in the 5'-end sequence of mouse Ano1 (mAno1) and its tissue-dependent regulation are poorly understood. We identified a novel 5'-terminal exon (designated exon 1a) of mAno1 instead of the known 5'-terminal exon (exon 0) using 5'-rapid amplification of cDNA ends (RACE) analysis. Unexpectedly, the novel 5'-end variant mAno1_Ex1a was abundantly expressed in many tissues including the salivary and mammary glands, rectum, lung, trachea and prostate. In contrast, the known variant mAno1_Ex0 predominated only in male reproductive tissues such as the epididymis and testis. In a heterologous expression system, mAno1_Ex0 encoded a longer protein than mAno1_Ex1a, and this long isoform was abolished by a mutation in the exon 0 start codon. Moreover, the mAno1_Ex0-specific N-terminal sequence was immunohistochemically detected in epididymis but not in salivary gland. Our data suggest that mAno1 expression is regulated via alternative promoters, and its transcriptional variation results in variation of the N-terminal sequence of the Ano1 protein due to the alternative translation initiation sites. These tissue-specific variations might contribute to the regulation of mAno1 expression and activity according to the physiological function of each tissue.

Vitamin D deficiency promotes prostatic hyperplasia in middle-age mice through exacerbating local inflammation

Vitamin D deficiency is especially prevalent in pregnant women and children. Our recent study demonstrated that vitamin D deficiency in early life disturbed testicular development. This study investigated the effects of vitamin D deficiency in early life on prostatic hyperplasia in middle-aged mice. In control group, dams and their male pups were fed with standard-chow diets. In VDD group, dams were fed with vitamin D deficient (VDD) diets throughout pregnancy and lactation. After weaning, male pups continued to be fed with VDD diets. As expected, prostate weight was elevated and prostatic hyperplasia was observed in VDD-fed mice. The number of prostatic Ki-67-positive epithelial cells, a proliferation marker, was increased in VDD-fed mice. Further analysis found that vitamin D deficiency promoted inflammatory infiltration and stromal fibrosis in prostate of middle-aged mice. Moreover, vitamin D deficiency activated NF-κB and up-regulated Il-6 mRNA in prostate of middle-aged mice. In addition, vitamin D deficiency activated prostatic STAT3, a proliferation pathway in middle-aged mice. Of interest, VDD-induced prostatic inflammation and hyperplasia were partially reversed when VDD diets was replaced with standard diets. These results provide evidence that vitamin D deficiency in early life promotes prostatic hyperplasia in middle-aged mice through exacerbating local inflammation.

Transmembrane member 16A participates in hydrogen peroxide-induced apoptosis by facilitating mitochondria-dependent pathway in vascular smooth muscle cells

BACKGROUND AND PURPOSE

Transmembrane member 16A (TMEM16A), an intrinsic constituent of the Ca2+ -activated Cl- channel, is involved in vascular smooth muscle cell (VSMC) proliferation and hypertension-induced cerebrovascular remodelling. However, the functional significance of TMEM16A for apoptosis in basilar artery smooth muscle cells (BASMCs) remains elusive. Here, we investigated whether and how TMEM16A contributes to apoptosis in BASMCs.

EXPERIMENTAL APPROACH

Cell viability assay, flow cytometry, Western blot, mitochondrial membrane potential assay, immunogold labelling and co-immunoprecipitation (co-IP) were performed.

KEY RESULTS

Hydrogen peroxide (H2 O2 ) induced BASMC apoptosis through a mitochondria-dependent pathway, including by increasing the apoptosis rate, down-regulating the ratio of Bcl-2/Bax and potentiating the loss of the mitochondrial membrane potential and release of cytochrome c from the mitochondria to the cytoplasm. These effects were all reversed by the silencing of TMEM16A and were further potentiated by the overexpression of TMEM16A. Endogenous TMEM16A was detected in the mitochondrial fraction. Co-IP revealed an interaction between TMEM16A and cyclophilin D, a component of the mitochondrial permeability transition pore (mPTP). This interaction was up-regulated by H2 O2 but restricted by cyclosporin A, an inhibitor of cyclophilin D. TMEM16A increased mPTP opening, resulting in the activation of caspase-9 and caspase-3. The results obtained with cultured BASMCs from TMEM16A smooth muscle-specific knock-in mice were consistent with those from rat BASMCs.

CONCLUSIONS AND IMPLICATIONS

These results suggest that TMEM16A participates in H2 O2 -induced apoptosis via modulation of mitochondrial membrane permeability in VSMCs. This study establishes TMEM16A as a target for therapy of several remodelling-related diseases.

The Mechanistic Role of the Calcium-Activated Chloride Channel ANO1 in Tumor Growth and Signaling

Multiple studies have described the high expression and amplification of Anoctamin 1 (ANO1) in various cancers, including, but not limited to breast cancer, head and neck cancer, gastrointestinal stromal tumors and glioblastoma. ANO1 has been demonstrated to be critical for tumor growth in breast and head and neck cancers through its regulation of EGFR signaling and pathway modulators like MAPK and protein kinase B. However, the discovery of ANO1 as a calcium activated chloride channel came as a surprise to the field and has given rise to many questions. How does a chloride channel promote oncogenesis? Is the chloride channel function of ANO1 important for its role in cancer? Does ANO1 exhibits chloride-independent functions in cancer cells? This review summarizes the current understanding of ANO1's function in cancer, provides a synopsis of the findings addressing the open questions in the field and gives an outlook on the promising future of ANO1 as a potential therapeutic target for the treatment of various cancers.

Comprehensive behavioral analyses of anoctamin1/TMEM16A-conditional knockout mice

AIMS

Anoctamin-1 (TMEM16A) is a calcium-activated chloride channel that is involved in numerous physiological conditions. Its role has been identified in electrophysiological and histological studies of genetic knockout animals. Recent cellular localization studies have shown that anoctamin-1 is co-expressed with presynaptic proteins, therefore its role in presynaptic terminals has been suggested. However, behavioral studies are lacking because conventional knockouts of anoctamin-1 are lethal after birth. In this study, we explored the role of anoctamin-1 in presynaptic terminals by analyzing the behavior of mice with conditional knockouts of anoctamin-1 in synapsin1-expressing cells.

MAIN METHODS

Using a synapsin1-Cre system, we selectively ablated anoctamin-1 in synapsin1 expressing cells. The mice were used in the behavioral experiments when they were between 6 and 9 months of age.

KEY FINDINGS

The mice with the conditional knockout of anoctamin-1 in synapsin1-expressing cells displayed impaired social behavior. In addition, the mice showed depressive-like behavior and decreased weight. However, these animals displayed normal locomotor activity, cognitive function, and motor coordination.

SIGNIFICANCE

These results suggested that anoctamin-1 is involved in psychiatric behavior because of its role in the regulation of synaptic transmission in presynaptic terminals.

Inhibition of ANO1/TMEM16A induces apoptosis in human prostate carcinoma cells by activating TNF-α signaling

Overexpression of the Ca²⁺-activated chloride channel ANO1/TMEM16A is implicated in tumorigenesis, and inhibition of ANO1 overexpression suppresses xenograft tumor growth and invasiveness. However, the underlying molecular mechanism for ANO1 inhibition in suppression of tumorigenesis remains unknown. Here, we show that silencing or inhibition of endogenous ANO1 inhibits cell growth, induces apoptosis and upregulates TNF-α expression in prostate cancer PC-3 cells. Enhancement of TNF-α signaling by ANO1 knockdown leads to upregulation of phosphorylated Fas-associated protein with death domain and caspase activation. Furthermore, silencing of ANO1 inhibits growth of PC-3 xenograft tumors in nude mice and induces apoptosis in tumors via upregulation of TNF-α signaling. Taken together, our findings provide mechanistic insight into promoting apoptosis in prostate cancer cells by ANO1 inhibition through upregulation of TNF-α signaling.

Early detection of prostate carcinogens by immunohistochemistry of HMGB2

Screening prostatic carcinogens is time-consuming due to the time needed to induce preneoplastic and neoplastic lesions. To overcome this, we investigated alternative molecular markers for detection of prostatic carcinogens in a short period in rats. After treatment with 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), expression of high-mobility group protein B2 (HMGB2) was up-regulated in rat ventral prostate. To evaluate the applicability of HMGB2 in the early detection of carcinogenicity of chemicals using animal models, we examined HMGB2 expression in prostate of rats. Six-week-old male F344 rats were gavaged for four weeks with a total of eight individual chemicals, divided into two categories based on prostate carcinogenicity. Animals were sacrificed at the end of the study and HMGB2 immunohistochemistry was performed. HMGB2 expression in least one prostate lobe was significantly increased by all four prostate carcinogens compared with the controls. In contrast, the four chemicals that were not carcinogenic in the prostate did not cause HMGB2 up-regulation. Additionally, high HMGB2 expression in neoplastic lesions in both rat and human was detected. Therefore HMGB2 expression may be a good screening tool for the identification of potential of prostate carcinogens.

Calcium-Activated Cl- Channel: Insights on the Molecular Identity in Epithelial Tissues

Calcium-activated chloride secretion in epithelial tissues has been described for many years. However, the molecular identity of the channel responsible for the Ca2+-activated Cl− secretion in epithelial tissues has remained a mystery. More recently, TMEM16A has been identified as a new putative Ca2+-activated Cl− channel (CaCC). The primary goal of this article will be to review the characterization of TMEM16A, as it relates to the physical structure of the channel, as well as important residues that confer voltage and Ca2+-sensitivity of the channel. This review will also discuss the role of TMEM16A in epithelial physiology and potential associated-pathophysiology. This will include discussion of developed knockout models that have provided much needed insight on the functional localization of TMEM16A in several epithelial tissues. Finally, this review will examine the implications of the identification of TMEM16A as it pertains to potential novel therapies in several pathologies.

Bioinformatic characterization of the Anoctamin Superfamily of Ca2+-activated ion channels and lipid scramblases

Our laboratory has developed bioinformatic strategies for identifying distant phylogenetic relationships and characterizing families and superfamilies of transport proteins. Results using these tools suggest that the Anoctamin Superfamily of cation and anion channels, as well as lipid scramblases, includes three functionally characterized families: the Anoctamin (ANO), Transmembrane Channel (TMC) and Ca²⁺-permeable Stress-gated Cation Channel (CSC) families; as well as four families of functionally uncharacterized proteins, which we refer to as the Anoctamin-like (ANO-L), Transmembrane Channel-like (TMC-L), and CSC-like (CSC-L1 and CSC-L2) families. We have constructed protein clusters and trees showing the relative relationships among the seven families. Topological analyses suggest that the members of these families have essentially the same topologies. Comparative examination of these homologous families provides insight into possible mechanisms of action, indicates the currently recognized organismal distributions of these proteins, and suggests drug design potential for the disease-related channel proteins.

Inhibition of calcium-activated chloride channel ANO1 suppresses proliferation and induces apoptosis of epithelium originated cancer cells

ANO1, a calcium-activated chloride channel, has been reported to be amplified or overexpressed in tissues of several cancers. However, reports on its roles in tumor progression obtained from cancer cell lines are inconsistent, suggesting that the role of ANO1 in tumorigenesis is likely dependent on either its expression level or cell-type expressing ANO1. To investigate the biological roles of ANO1 in different tumor cells, we, in this study, selected several cancer cell lines and a normal HaCaT cell line with high expression levels of ANO1, and examined the function of ANO1 in these cells using approaches of lentiviral knockdown and pharmacological inhibition. We found that ANO1 knockdown significantly inhibited cell proliferation and induced cell apoptosis in either tumor cell lines or normal HaCaT cell line. Moreover, silencing ANO1 arrested cancer cells at G1 phase of cell cycle. Treatment with ANO1 inhibitor CaCC_inh-A01 reduced cell viability in a dose-dependent manner. Furthermore, both ANO1 inhibitors CaCC_inh-A01 and T16A_inh-A01 significantly suppressed cell migration. Our findings show that ANO1 overexpression promotes cancer cell proliferation and migration; and genetic or pharmacological inhibition of ANO1 induces apoptosis and cell cycle arrest at G1 phase in different types of epithelium-originated cancer cells.

Anoctamin 9/TMEM16J is a cation channel activated by cAMP/PKA signal

Anoctamins (ANOs) are multifunctional membrane proteins that consist of 10 homologs. ANO1 (TMEM16A) and ANO2 (TMEM16B) are anion channels activated by intracellular calcium that meditate numerous physiological functions. ANO6 is a scramblase that redistributes phospholipids across the cell membrane. The other homologs are not well characterized. We found ANO9/TMEM16J is a cation channel activated by a cAMP-dependent protein kinase A (PKA). Intracellular cAMP-activated robust currents in whole cells expressing ANO9, which were inhibited by a PKA blocker. A cholera toxin that persistently stimulated adenylate cyclase activated ANO9 as did the application of PKA. The cAMP-induced ANO9 currents were permeable to cations. The cAMP-dependent ANO9 currents were augmented by intracellular Ca²⁺. Ano9 transcripts were predominant in the intestines. Human intestinal SW480 cells expressed high levels of Ano9 transcripts and showed PKA inhibitor-reversible cAMP-dependent currents. We conclude that ANO9 is a cation channel activated by a cAMP/PKA pathway and could play a role in intestine function.

Cell-specific mechanisms of TMEM16A Ca2+-activated chloride channel in cancer

TMEM16A (known as anoctamin 1) Ca2+-activated chloride channel is overexpressed in many tumors. TMEM16A overexpression can be caused by gene amplification in many tumors harboring 11q13 amplification. TMEM16A expression is also controlled in many cancer cells via transcriptional regulation, epigenetic regulation and microRNAs. In addition, TMEM16A activates different signaling pathways in different cancers, e.g. the EGFR and CAMKII signaling in breast cancer, the p38 and ERK1/2 signaling in hepatoma, the Ras-Raf-MEK-ERK1/2 signaling in head and neck squamous cell carcinoma and bladder cancer, and the NFκB signaling in glioma. Furthermore, TMEM16A overexpression has been reported to promote, inhibit, or produce no effects on cell proliferation and migration in different cancer cells. Since TMEM16A exerts different roles in different cancer cells via activation of distinct signaling pathways, we try to develop the idea that TMEM16A regulates cancer cell proliferation and migration in a cell-dependent mechanism. The cell-specific role of TMEM16A may depend on the cellular environment that is predetermined by TMEM16A overexpression mechanisms specific for a particular cancer type. TMEM16A may exert its cell-specific role via its associated protein networks, phosphorylation by different kinases, and involvement of different signaling pathways. In addition, we discuss the role of TMEM16A channel activity in cancer, and its clinical use as a prognostic and predictive marker in different cancers. This review highlights the cell-type specific mechanisms of TMEM16A in cancer, and envisions the promising use of TMEM16A inhibitors as a potential treatment for TMEM16A-overexpressing cancers.

Molecular, biophysical, and pharmacological properties of calcium-activated chloride channels

Calcium-activated chloride channels (CaCCs) are a family of anionic transmembrane ion channels. They are mainly responsible for the movement of Cl^- and other anions across the biological membranes, and they are widely expressed in different tissues. Since the Cl^- flow into or out of the cell plays a crucial role in hyperpolarizing or depolarizing the cells, respectively, the impact of intracellular Ca²⁺ concentration on these channels is attracting a lot of attentions. After summarizing the molecular, biophysical, and pharmacological properties of CaCCs, the role of CaCCs in normal cellular functions will be discussed, and I will emphasize how dysregulation of CaCCs in pathological conditions can account for different diseases. A better understanding of CaCCs and a pivotal regulatory role of Ca²⁺ can shed more light on the therapeutic strategies for different neurological disorders that arise from chloride dysregulation, such as asthma, cystic fibrosis, and neuropathic pain.

Inhibition of ANO1 by luteolin and its cytotoxicity in human prostate cancer PC-3 cells

Anoctamin 1 (ANO1), a calcium-activated chloride channel, is highly amplified in prostate cancer, the most common form of cancer and leading causes of cancer death in men, and downregulation of ANO1 expression or its functional activity is known to inhibit cell proliferation, migration and invasion in prostate cancer cells. Here, we performed a cell-based screening for the identification of ANO1 inhibitors as potential anticancer therapeutic agents for prostate cancer. Screening of ~300 selected bioactive natural products revealed that luteolin is a novel potent inhibitor of ANO1. Electrophysiological studies indicated that luteolin potently inhibited ANO1 chloride channel activity in a dose-dependent manner with an IC₅₀ value of 9.8 μM and luteolin did not alter intracellular calcium signaling in PC-3 prostate cancer cells. Luteolin inhibited cell proliferation and migration of PC-3 cells expressing high levels of ANO1 more potently than that of ANO1-deficient PC-3 cells. Notably, luteolin not only inhibited ANO1 channel activity, but also strongly decreased protein expression levels of ANO1. Our results suggest that downregulation of ANO1 by luteolin is a potential mechanism for the anticancer effect of luteolin.

MicroRNA-381 inhibits the metastasis of gastric cancer by targeting TMEM16A expression

Background

MicroRNA-381 (miR-381) has been reported to play suppressive or promoting roles in different malignancies. However, the expression level, biological function, and underlying mechanisms of miR-381 in gastric cancer remain poorly understood. Our previous study indicated that transmembrane protein 16A (TMEM16A) contributed to migration and invasion of gastric cancer and predicted poor prognosis. In this study, we found that miR-381 inhibited the metastasis of gastric cancer through targeting TMEM16A expression.

Methods

MiR-381 expression was analyzed using bioinformatic software on open microarray datasets from the Gene Expression Omnibus (GEO) and confirmed by quantitative RT-PCR (qRT-PCR) in human gastric cancer tissues and cell lines. Cell proliferation was investigated using MTT and cell count assays, and cell migration and invasion abilities were evaluated by transwell assay. Xenograft nude mouse models were used to observe tumor growth and pulmonary metastasis. Luciferase reporter assay, western blot, enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry were employed to explore the mechanisms of the effect of miR-381 on gastric cancer cells.

Results

MiR-381 was significantly down-regulated in gastric cancer tissues and cell lines. Low expression of miR-381 was negatively related to lymph node metastasis, advanced tumor stage and poor prognosis. MiR-381 decreased gastric cancer cell proliferation, migration and invasion in vitro and in vivo. TMEM16A was identified as a direct target of miR-381 and the expression of miR-381 was inversely correlated with TMEM16A expression in gastric cancer tissues. Combination analysis of miR-381 and TMEM16A revealed the improved prognostic accuracy for gastric cancer patients. Moreover, miR-381 inhibited TGF-β signaling pathway and down-regulated epithelial–mesenchymal transition (EMT) phenotype partially by mediating TMEM16A.

Conclusions

MiR-381 may function as a tumor suppressor by directly targeting TMEM16A and regulating TGF-β pathway and EMT process in the development of progression of gastric cancer. MiR-381/TMEM16A may be a novel therapeutic candidate target in gastric cancer treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-017-0499-z) contains supplementary material, which is available to authorized users.

Inhibitory Effect of Yongdamsagan-Tang Water Extract, a Traditional Herbal Formula, on Testosterone-Induced Benign Prostatic Hyperplasia in Rats

Yongdamsagan-tang, a traditional herbal formula, is used widely for the treatment of inflammation and viral diseases. In this study, we investigated whether Yongdamsagan-tang water extract (YSTE) affects testosterone propionate- (TP-) induced benign prostatic hyperplasia (BPH) in a rat model. To induce BPH, rats were injected subcutaneously with 10 mg/kg of TP every day. YSTE was administrated daily by oral gavage at doses of 200 and 500 mg/kg along with the TP injection. After 4 weeks, prostates were collected, weighed, and analyzed. The relative prostrate weight was significantly lower in both YSTE groups (200 and 500 mg/kg/day) compared with the TP-induced BPH group. YSTE administration reduced the expression of proliferation markers PCNA, cyclin D1, and Ki-67 and the histological abnormalities observed in the prostate in TP-induced BPH rats. YSTE attenuated the increase in the TP-induced androgen concentration in the prostate. The YSTE groups also showed decreased lipid peroxidation and increased glutathione reductase activity in the prostate. These findings suggest that YSTE effectively prevented the development of TP-induced BPH in rats through antiproliferative and antioxidative activities and might be useful in the clinical treatment of BPH.

Ani9, A Novel Potent Small-Molecule ANO1 Inhibitor with Negligible Effect on ANO2

Anoctamin1 (ANO1)/transmembrane protein 16A (TMEM16A), a calcium-activated chloride channel (CaCC), is involved in many physiological functions such as fluid secretion, smooth muscle contraction, nociception and cancer progression. To date, only a few ANO1 inhibitors have been described, and these have low potency and selectivity for ANO1. Here, we performed a high-throughput screening to identify highly potent and selective small molecule inhibitors of ANO1. Three novel ANO1 inhibitors were discovered from screening of 54,400 synthetic small molecules, and they were found to fully block ANO1 channel activity with an IC₅₀ < 3 μM. Electrophysiological analysis revealed that the most potent inhibitor, 2-(4-chloro-2-methylphenoxy)-N-[(2-methoxyphenyl)methylideneamino]-acetamide (Ani9), completely inhibited ANO1 chloride current with submicromolar potency. Notably, unlike previous small-molecule ANO1 inhibitors identified to date, Ani9 displayed high selectivity for ANO1 as compared to ANO2, which shares a high amino acid homology to ANO1. In addition, Ani9 did not affect the intracellular calcium signaling and CFTR chloride channel activity. Our results suggest that Ani9 may be a useful pharmacological tool for studying ANO1 and a potential development candidate for drug therapy of cancer, hypertension, pain, diarrhea and asthma.

Suppression of 14-3-3γ-mediated surface expression of ANO1 inhibits cancer progression of glioblastoma cells

Anoctamin-1 (ANO1) acts as a Ca²⁺-activated Cl⁻ channel in various normal tissues, and its expression is increased in several different types of cancer. Therefore, understanding the regulation of ANO1 surface expression is important for determining its physiological and pathophysiological functions. However, the trafficking mechanism of ANO1 remains elusive. Here, we report that segment a (N-terminal 116 amino acids) of ANO1 is crucial for its surface expression, and we identified 14-3-3γ as a binding partner for anterograde trafficking using yeast two-hybrid screening. The surface expression of ANO1 was enhanced by 14-3-3γ, and the Thr9 residue of ANO1 was critical for its interaction with 14-3-3γ. Gene silencing of 14-3-3γ and/or ANO1 demonstrated that suppression of ANO1 surface expression inhibited migration and invasion of glioblastoma cells. These findings provide novel therapeutic implications for glioblastomas, which are associated with poor prognosis.

Recent advances in therapeutic strategies that focus on the regulation of ion channel expression

A number of different ion channel types are involved in cell signaling networks, and homeostatic regulatory mechanisms contribute to the control of ion channel expression. Profiling of global gene expression using microarray technology has recently provided novel insights into the molecular mechanisms underlying the homeostatic and pathological control of ion channel expression. It has demonstrated that the dysregulation of ion channel expression is associated with the pathogenesis of neural, cardiovascular, and immune diseases as well as cancers. In addition to the transcriptional, translational, and post-translational regulation of ion channels, potentially important evidence on the mechanisms controlling ion channel expression has recently been accumulated. The regulation of alternative pre-mRNA splicing is therefore a novel therapeutic strategy for the treatment of dominant-negative splicing disorders. Epigenetic modification plays a key role in various pathological conditions through the regulation of pluripotency genes. Inhibitors of pre-mRNA splicing and histone deacetyalase/methyltransferase have potential as potent therapeutic drugs for cancers and autoimmune and inflammatory diseases. Moreover, membrane-anchoring proteins, lysosomal and proteasomal degradation-related molecules, auxiliary subunits, and pharmacological agents alter the protein folding, membrane trafficking, and post-translational modifications of ion channels, and are linked to expression-defect channelopathies. In this review, we focused on recent insights into the transcriptional, spliceosomal, epigenetic, and proteasomal regulation of ion channel expression: Ca(2+) channels (TRPC/TRPV/TRPM/TRPA/Orai), K(+) channels (voltage-gated, KV/Ca(2+)-activated, KCa/two-pore domain, K2P/inward-rectifier, Kir), and Ca(2+)-activated Cl(-) channels (TMEM16A/TMEM16B). Furthermore, this review highlights expression of these ion channels in expression-defect channelopathies.

Cellular functions of TMEM16/anoctamin

Ca²⁺-activated Cl⁻ channels (CaCCs) are a class of Cl⁻ channels activated by intracellular Ca²⁺ that are known to mediate numerous physiological functions. In 2008, the molecular identity of CaCCs was found to be anoctamin 1 (ANO1/TMEM16A). Its roles have been studied in electrophysiological, histological, and genetic aspects. ANO1 is known to mediate Cl⁻ secretion in secretory epithelia such as airways, salivary glands, intestines, renal tubules, and sweat glands. ANO1 is a heat sensor activated by noxious heat in somatosensory neurons and mediates acute pain sensation as well as chronic pain. ANO1 is also observed in vascular as well as airway smooth muscles, controlling vascular tone as well as airway hypersensitivity. ANO1 is upregulated in numerous types of cancers and thus thought to be involved in tumorigenesis. ANO1 is also found in proliferating cells. In addition to ANO1, involvement of its paralogs in pathophysiological conditions was also reported. ANO2 is involved in olfaction, whereas ANO6 works as a scramblase whose mutation causes a rare bleeding disorder, the Scott syndrome. ANO5 is associated with muscle and bone diseases. Recently, an X-ray crystal structure of a fungal TMEM16 was reported, which explains a precise molecular gating mechanism as well as ion conduction or phospholipid transport across the plasma membrane.