Inhibitory effects of berberine on voltage- and calcium-activated potassium currents in human myeloma cells

Investigating the influence of XAV-939, a tankyrase inhibitor, on the density and gating of erg-mediated K+ currents in mouse MA-10 Leydig tumor cells

XAV-939(XAV) is a chemical compound that inhibits the activity of tankyrase. However, the precise way in which XAV alters membrane ionic currents is not well understood. In this study,our goal was to examine the impact of XAV on the ionic currents in mouse MA-10 Leydig cells, specifically focusing on the magnitude, gating properties,and voltage-dependent hysteresis of erg-mediated K+currents(IK(erg)). In our whole-cell current recordings we observed that the addition of XAV inhibited the density of IK(erg) in a concentration-dependent manner with an IC50 of 3.1 μM. Furthermore we found that continued exposure to XAV, further addition of neither liraglutide nor insulin-like growth factor-1 counteracted XAV-mediated inhibition of IK(erg). Additionally the presence of XAV suppressed the mean current versus voltage relationship of IK(erg) across the entire voltage-clamp step analyzed. This compound shifted the steady-state activation curve of IK(erg) to a less negative potential by approximately 12 mV. The presence of XAV increased the time constant of deactivating IK(erg) in MA-10 cells. The voltage-dependent clockwise hysteresis of IK(erg) responding to prolonged upright isosceles-triangular ramp voltage became diminished by adding XAV; moreover subsequent addition of NS3623 effectively reversed XAV-induced decrease of hysteretic area of IK(erg). XAV also inhibited the proliferation of this cell line and the IC50 value of XAV-induced inhibition of cell proliferation was 2.8M. Overall the suppression of IK(erg) by XAV may serve as a significant ionic mechanism that contribute to the functional properties of MA-10 cells. However, it is important to note that this effect cannot be attributed solely to the inhibition of tankyrase.

Ion Channels in Multiple Myeloma: Pathogenic Role and Therapeutic Perspectives

Ion channels are pore-forming proteins that allow ions to flow across plasma membranes and intracellular organelles in both excitable and non-excitable cells. They are involved in the regulation of several biological processes (i.e., proliferation, cell volume and shape, differentiation, migration, and apoptosis). Recently, the aberrant expression of ion channels has emerged as an important step of malignant transformation, tumor progression, and drug resistance, leading to the idea of “onco-channelopathy”. Here, we review the contribution of ion channels and transporters in multiple myeloma (MM), a hematological neoplasia characterized by the expansion of tumor plasma cells (MM cells) in the bone marrow (BM). Deregulation of ion channels sustains MM progression by modulating intracellular pathways that promote MM cells’ survival, proliferation, and drug resistance. Finally, we focus on the promising role of ion channels as therapeutic targets for the treatment of MM patients in a combination strategy with currently used anti-MM drugs to improve their cytotoxic activity and reduce adverse effects.

Berberine Suppresses Lung Metastasis of Cancer via Inhibiting Endothelial Transforming Growth Factor Beta Receptor 1

This study investigated the effects of berberine (BBR) on pancreatic cancer (PC) lung metastasis and explored the underlying mechanisms, using a BALB/C-nu/nu nude mouse model injected with PC cells (AsPC-1). Intragastric administration of BBR dose-dependently improves survival of mice intravenously injected with AsPC-1 cells, and reduces lung metastasis. Especially, BBR significantly reduces lung infiltration of circulating tumor cells (CTCs) 24 h after AsPC-1 cells injection. In vitro, tumor cells (TCs) trigger endothelial barrier disruption and promote trans-endothelial migration of CFSE-labeled TCs. BBR treatment effectively ameliorates TC-induced endothelial disruption, an effect that is diminished by inhibiting transforming growth factor-β receptor 1 (TGFBR1). Blocking TGFBR1 blunts the anti-metastatic effect of BBR in vivo. Mechanistically, BBR binds to the intercellular portion of TGFBR1, suppresses its enzyme activities, and protects endothelial barrier disruption by TCs which express higher levels of TGF-β1. Hence, BBR might be a promising drug for reducing PC lung metastasis in clinical practice.

Research Progress on Natural Products’ Therapeutic Effects on Atrial Fibrillation by Regulating Ion Channels

Antiarrhythmic drugs (AADs) have a therapeutic effect on atrial fibrillation (AF) by regulating the function of ion channels. However, several adverse effects and high recurrence rates after drug withdrawal seriously affect patients’ medication compliance and clinical prognosis. Thus, safer and more effective drugs are urgently needed. Active components extracted from natural products are potential choices for AF therapy. Natural products like Panax notoginseng (Burk.) F.H. Chen, Sophora flavescens Ait., Stephania tetrandra S. Moore., Pueraria lobata (Willd.) Ohwi var. thomsonii (Benth.) Vaniot der Maesen., and Coptis chinensis Franch. have a long history in the treatment of arrhythmia, myocardial infarction, stroke, and heart failure in China. Based on the classification of chemical structures, this article discussed the natural product components’ therapeutic effects on atrial fibrillation by regulating ion channels, connexins, and expression of related genes, in order to provide a reference for development of therapeutic drugs for atrial fibrillation.

High ability of zileuton ((±)-1-(1-benzo[b]thien-2-ylethyl)-1-hydroxyurea) to stimulate IK(Ca) but suppress IK(DR) and IK(M) independently of 5-lipoxygenase inhibition

Zileuton (Zyflo®) is regarded to be an inhibitor of 5-lipoxygenase. Although its effect on Ca²⁺-activated K⁺ currents has been reported, its overall ionic effects on neurons are uncertain. In whole-cell current recordings, zileuton increased the amplitude of Ca²⁺-activated K⁺ currents with an EC₅₀ of 3.2 μM in pituitary GH₃ lactotrophs. Furthermore, zileuton decreased the amplitudes of both delayed-rectifier K⁺ current (I_K(DR)) and M-type K⁺ current (I_K(M)). Conversely, no modification of hyperpolarization-activated cation current (I_h) was demonstrated in its presence of zileuton, although the subsequent addition of cilobradine effectively suppressed the current. In inside-out current recordings, the addition of zileuton to the bath increased the probability of large-conductance Ca²⁺-activated K⁺ (BK_Ca) channels; however, the subsequent addition of GAL-021 effectively reversed the stimulation of channel activity. The kinetic analyses showed an evident shortening in the slow component of mean closed time of BK_Ca channels in the presence of zileuton, with minimal change in mean open time or that in the fast component of mean closed time. The elevation of BK_Ca channels caused by zileuton was also observed in hippocampal mHippoE-14 neurons, without any modification of single-channel amplitude. In conclusion, except for its suppression of 5-lipoxygenase, our results indicate that zileuton does not exclusively act on BK_Ca channels, and its inhibitory effects on I_K(DR) and I_K(M) may combine to exert strong influence on the functional activities of electrically excitable cells in vivo.

Actions of FTY720 (Fingolimod), a Sphingosine-1-Phosphate Receptor Modulator, on Delayed-Rectifier K+ Current and Intermediate-Conductance Ca2+-Activated K+ Channel in Jurkat T-Lymphocytes

FTY720 (fingolimod), a modulator of sphingosine-1-phosphate receptors, is known to produce the immunomodulatory actions and to be beneficial for treating the relapsing multiple sclerosis. However, whether it exerts any effects on membrane ion currents in immune cells remains largely unknown. Herein, the effects of FTY720 on ionic currents in Jurkat T-lymphocytes were investigated. Cell exposure to FTY720 suppressed the amplitude of delayed-rectifier K⁺ current (I_K(DR)) in a time- and concentration-dependent manner with an IC₅₀ value of 1.51 μM. Increasing the FTY720 concentration not only decreased the I_K(DR) amplitude but also accelerated the inactivation time course of the current. By using the minimal reaction scheme, the effect of FTY720 on I_K(DR) inactivation was estimated with a dissociation constant of 3.14 μM. FTY720 also shifted the inactivation curve of I_K(DR) to a hyperpolarized potential with no change in the slope factor, and recovery from I_K(DR) became slow during the exposure to this compound. Cumulative inactivation for I_K(DR) in response to repetitive depolarizations was enhanced in the presence of FTY720. In SEW2871-treated cells, FTY720-induced inhibition of I_K(DR) was attenuated. This compound also exerted a stimulatory action on the activity of intermediate-conductance Ca²⁺-activated K⁺ channels in Jurkat T-lymphocytes. However, in NSC-34 neuronal cells, FTY720 did not modify the inactivation kinetics of KV3.1-encoded I_K(DR), although it suppressed I_K(DR) amplitude in these cells. Collectively, the perturbations by FTY720 on different types of K⁺ channels may contribute to the functional activities of immune cells, if similar findings appear in vivo.

High Effectiveness in Actions of Carfilzomib on Delayed-Rectifier K+ Current and on Spontaneous Action Potentials

Carfilzomib (CFZ, Kyprolis^®) is widely recognized as an irreversible inhibitor of proteasome activity; however, its actions on ion currents in electrically excitable cells are largely unresolved. The possible actions of CFZ on ionic currents and membrane potential in pituitary GH₃, A7r5 vascular smooth muscle, and heart-derived H9c2 cells were extensively investigated in this study. The presence of CFZ suppressed the amplitude of delayed-rectifier K⁺ current (I_K(DR)) in a time-, state-, and concentration-dependent manner in pituitary GH₃ cells. Based on minimal reaction scheme, the value of dissociation constant for CFZ-induced open-channel block of I_K(DR) in these cells was 0.33 µM, which is similar to the IC₅₀ value (0.32 µM) used for its efficacy on inhibition of I_K(DR) amplitude. Recovery from I_K(DR) block by CFZ (0.3 µM and 1 µM) could be well fitted by single exponential with 447 and 645 ms, respectively. The M-type K⁺ current, another type of K⁺ current elicited by low-threshold potential, was slightly suppressed by CFZ (1 µM). Under current-clamp condition, addition of CFZ depolarized GH₃ cells, broadened the duration of action potentials as well as raised the firing frequency. In A7r5 vascular smooth muscle cells or H9c2 cardiac cells, the CFZ-induced inhibition of I_K(DR) remained efficacious. Therefore, our study led us to reflect that CFZ or other structurally similar compounds should somehow act on the activity of membrane K_V channels through which they influence the functional activities in different types of electrically excitable cells such as endocrine, neuroendocrine cells, smooth muscle cells, or heart cells, if similar in vivo findings occur.

Differential suppression of delayed-rectifier and inwardly rectifier K+ currents by a group of ent-kaurane-type diterpenoids from Croton tonkinensis, in microglial cells

Croton is an extensive flowering plant genus in the spurge family, Euphorbiaceae. Three croton compounds with the common ent-kaurane skeleton were purified from Croton tonkinensis. By using patch-clamp recording technique, we thoroughly examined the effect of a group of croton compounds, croton-01 (ent-18-acetoxy-7α-hydroxykaur-16-en-15-one), croton-02 (ent-7α,14β-dihydroxykaur-16-en-15-one), and croton-03 (ent-1β-acetoxy-7α,14β-dihydroxykaur-16-en-15-one), on the membrane current in SM826 and BV2 microglial cells. Although neither voltage-gated Na⁺ nor Ca²⁺ currents were present in these cells, both delayed-rectifier K⁺ outward (I_K(DR)) and inwardly rectifying K⁺ currents (I_K(IR)) were readily detected. Croton-03 differentially caused inhibition of I_K(DR) or I_K(IR) in a concentration-dependent manner. According to a minimal scheme, the shortening of the time constant in either the I_K(DR)-related block or I_K(IR) caused by different concentrations of croton-03 was quantitatively estimated with a dissociation constant of 6.45 and 29.5 μM, respectively. In SM826 cells differentiated with β-amyloid, inhibitory action on these K⁺ currents remained unaltered. In ultraviolet C-irradiated cells, the magnitude of I_K(IR) was still decreased by addition of croton-03. Therefore, our study suggests that these ent-kaurane diterpenoids ought to somehow act on the cellular mechanisms by which they influence the functional activities of microglial cells.

Application of Traditional Chinese Medicine in Treatment of Atrial Fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia, which is related to many cardiac and cerebral vascular diseases, especially stroke. It can therefore increase cardiovascular mortality and all-cause death. The current treatments of AF remain to be western drugs and radiofrequency ablation which are limited by the tolerance of patients, adverse side effects, and high recurrence rate, especially for the elderly. On the contrary, traditional Chinese medicine (TCM) with long history of use involves various treatment methods, including Chinese herbal medicines (CHMs) or bioactive ingredients, Chinese patent medicines, acupuncture, Qigong, and Tai Chi Chuan. With more and more researches reported, the active roles of TCM in AF management have been discovered. Then it is likely that TCM would be effective preventive means and valuable additional remedy for AF. The potential mechanisms further found by numerous experimental studies showed the distinct characteristics of TCM. Some CHMs or bioactive ingredients are atrial-selective, while others are multichannel and multifunctional. Therefore, in this review we summarized the treatment strategies reported in TCM, with the purpose of providing novel ideas and directions for AF management.

The Structure-Dependent Electric Release and Enhanced Oxidation of Drug in Graphene Oxide-Based Nanocarrier Loaded with Anticancer Herbal Drug Berberine

The aim of the current investigation is to explore graphene oxide (GO) special electric and electrochemical properties in modulating and tuning drug delivery in tumor special environment of electrophysiology. The electric-sensitive drug release and redox behavior of GO-bearing berberine (Ber) was studied. Drug release in cell potential was applied in a designed electrode system: tumor environment was simulated at pH 6.2 with 0.1 V pulse voltage, whereas the normal was at pH 7.4 with 0.2 V. Quite different from the pH-depended profile, the electricity-triggered behavior indicated a high correlation with the carriers' structure: GO-based nanocomposite showed a burst release on its special "skin effect," whereas the PEGylated ones released slowly owing to the electroviscous effect of polymer. Cyclic voltammetry was used to investigate the redox behaviors of colloid PEGylated GO toward absorbed Ber in pH 5.8 and 7.2 solutions. After drug loading, the oxidation of Ber was enhanced in a neutral environment, whereas the enhancement of PEG-GO was in an acidic one, which means a possible increased susceptibility of their biotransformation in vivo. The studies designed in this work may help to establish a kind of carrier system for the sensitive delivery and metabolic regulation of drugs according to the different electrophysiological environment in tumor therapy.

The Use of Chemical-Chemical Interaction and Chemical Structure to Identify New Candidate Chemicals Related to Lung Cancer

Lung cancer causes over one million deaths every year worldwide. However, prevention and treatment methods for this serious disease are limited. The identification of new chemicals related to lung cancer may aid in disease prevention and the design of more effective treatments. This study employed a weighted network, constructed using chemical-chemical interaction information, to identify new chemicals related to two types of lung cancer: non-small lung cancer and small-cell lung cancer. Then, a randomization test as well as chemical-chemical interaction and chemical structure information were utilized to make further selections. A final analysis of these new chemicals in the context of the current literature indicates that several chemicals are strongly linked to lung cancer.

The therapeutic potential of Berberine chloride hydrate against harmaline-induced motor impairments in a rat model of tremor

Essential tremor (ET) is a progressive neurological disorder with motor and non-motor symptoms. It has conclusively been shown that modulation of glutamate receptors could ameliorate ET. Recent studies have suggested that Berberine (BBR) has an inhibitory effect on glutamate receptors. Therefore, BBR may have therapeutic effects on ET. In this study, male Wistar rats (n=10 in each group) weighing 40-60 g were divided into control, harmaline (30 mg/kg, i.p.) and berberine (10, 20 or 50mg/kg, i.p, 15 min before harmaline injection) groups. Open field, rotarod, wire grip and foot print tests were used to evaluate motor performance. The results indicated that the administration of BBR (10 and 20mg/kg) attenuated harmaline-induced tremor in rats, but the beneficial effects of BBR could not be identified at dose 50mg/kg. In addition, BBR ameliorated gait disturbance in doses of 10 and 20mg/kg. The high dose of BBR not only failed to recover step width but also showed an adverse effect on left and right step length. The results indicate that BBR only in dose of 20mg/kg recovers mobility duration. The current study found a dose-dependent manner for the therapeutic effects of BBR in ET. Our study provides the initial evidence for the effects of BBR on motor function. Since BBR exerts its effects mainly through regulation of neurotransmitter release or blocke of NMDA receptors, thus, it is predicted that BBR ameliorate harmaline effect through blockade of NMDA receptors or glutamate release. This is an important issue for future research to evaluate the possible mechanisms involved.

Effects of ibandronate sodium, a nitrogen-containing bisphosphonate, on intermediate-conductance calcium-activated potassium channels in osteoclast precursor cells (RAW 264.7)

Ibanonate sodium (Iban), a nitrogen-containing bisphosphonate, is recognized to reduce skeletal complications through an inhibition of osteoclast-mediated bone resorption. However, how this drug interacts with ion channels in osteoclasts and creates anti-osteoclastic activity remains largely unclear. In this study, we investigated the possible effects of Iban and other related compounds on ionic currents in the osteoclast precursor RAW 264.7 cells. Iban suppressed the amplitude of whole-cell K(+) currents (I K) in a concentration-dependent manner with an IC50 value of 28.9 μM. The I K amplitude was sensitive to block by TRAM-34 and Iban-mediated inhibition of I K was reversed by further addition of DCEBIO, an activator of intermediate-conductance Ca(2+)-activated K(+) (IKCa) channels. Intracellular dialysis with Iban diminished I K amplitude and further addition of ionomycin reversed its inhibition. In 17β-estradiol-treated cells, Iban-mediated inhibition of I K remained effective. In cell-attached current recordings, Iban applied to bath did not modify single-channel conductance of IKCa channels; however, it did reduce channel activity. Iban-induced inhibition of IKCa channels was voltage-dependent. As IKCa-channel activity was suppressed by KN-93, subsequent addition of Iban did not further decrease the channel open probability. Iban could not exert any effect on inwardly rectifying K(+) current in RAW 264.7 cells. Under current-clamp recordings, Iban depolarized the membrane of RAW 264.7 cells and DCEBIO reversed Iban-induced depolarization. Iban also suppressed lipopolysaccharide-stimulated migration of RAW 264.7 cells in a concentration-dependent manner. Therefore, the inhibition by Iban of IKCa channels would be an important mechanism underlying its actions on the functional activity of osteoclasts occurring in vivo.

Effect of berberine on activity and mRNA expression of N-acetyltransferase in human lung cancer cell line A549

OBJECTIVE

To study the effects of berberine on activity and mRNA expression of N-acetyltransferase in human lung cancer cell line A549.

METHODS

N-acetyltransferase antibodies were prepared. The human lung cancer A549 cells were cultivated randomly in the wells of culture plate, and divided into the control group, and berberine 0.0008, 0.008, 0.08, 0.8 and 1.6 mM treatment groups, with 3 wells for each group. 24 h later, A549 cells in each group were collected respectively, the content of N-acetyltransferase was detected by Flow cytometry, and the mRNA expression of N-acetyltransferase was observed by reverse transcription polymerase chain reaction.

RESULTS

The N-acetyltransferase content in human lung cancer A549 cells decreased with the increasing of berberine concentration, significantly lower than that in the control group (P < 0.05 or P < 0.001); and the mRNA expression of N-acetyltransferase also decreased with the increasing of berberine concentration, significantly lower in Huangliansu treatment groups (P < 0.001).

CONCLUSION

Berberine can inhibit the activity of N-acetyltransferase in human lung cancer cell line A549, and shows negative correlations of dose and time in a certain extent. The inhibited gene expression of N-acetyltransferase in human lung cancer A549 cell may probably represent one of the mechanisms for its antineoplastic effect.

Set9, NF-κB, and microRNA-21 mediate berberine-induced apoptosis of human multiple myeloma cells

AIM

To investigate the mechanisms by which berberine suppressed the proliferation of human multiple myeloma cells.

METHODS

Human U266 multiple myeloma cell line was tested. Cell proliferation, apoptosis, ultramicrostructure and secretion function were examined using Cell Counting Kit-8 (CCK8), flow cytometry (FCM), electron and fluorescence microscopy, as well as ELISA assay. The microRNAs (miRs) and transcription factors in U266 cells were detected using arrays and verified by qRT-PCR. EMSA and luciferase assays were used to verify the p65-dependent transactivation of miR-21 gene.

RESULTS

Treatment of U266 cells with berberine (40-160 μmol/L) suppressed cell proliferation and IL-6 secretion in dose- and time-dependent manners. Meanwhile, berberine dose-dependently induced ROS generation, G(2)/M phase arrest and apoptosis in U266 cells, and decreased the levels of miR-21 and Bcl-2. Overexpression of miR-21 counteracted berberine-induced suppression of cell proliferation and IL-6 secretion. In U266 cells treated with berberine (80 μmol/L), the activity of NF-κB was decreased by approximately 50%, followed by significant reduction of miR-21 level. berberine (80-160 μmol/L) increased the level of Set9 (lysine methyltransferase) by more than 2-fold, caused methylation of the RelA subunit, which inhibited NF-κB nuclear translocation and miR-21 transcription. In U266 cells treated with berberine (80 μmol/L), knockdown of Set9 with siRNAs significantly increased NF-κB protein level accompanying with a partial recovery of proliferation.

CONCLUSION

In U266 cells, berberine suppresses NF-κB nuclear translocation via Set9-mediated lysine methylation, leads to decrease in the levels miR21 and Bcl-2, which induces ROS generation and apoptosis.

Evidence for aconitine-induced inhibition of delayed rectifier K(+) current in Jurkat T-lymphocytes

Aconitine (ACO) is a highly toxic diterpenoid alkaloid and known to exert the immunomodulatory action. However, whether it has any effects on ion currents in immune cells remains unknown. The effects of ACO and other related compounds on ion currents in Jurkat T-lymphocytes were investigated in this study. ACO suppressed the amplitude of delayed-rectifier K(+) current (I(K(DR))) in a time- and concentration-dependent manner. Margatoxin (100 nM), a specific blocker of K(V)1.3-encoded current, decreased the I(K(DR)) amplitude in these cells and the ACO-induced inhibition of I(K(DR)) was not reversed by 1-ethyl-2-benzimidazolinone (30 μM) or nicotine (10 μM). The IC(50) value for ACO-mediated inhibition of I(K(DR)) was 5.6 μM. ACO accelerated the inactivation of I(K(DR)) with no change in the activation rate of this current. Increasing the ACO concentration not only reduced the I(K(DR)) amplitude, but also accelerated the inactivation time course of the current. With the aid of minimal binding scheme, the inhibitory action of ACO on I(K(DR)) was estimated with a dissociation constant of 6.8 μM. ACO also shifted the inactivation curve of I(K(DR)) to a hyperpolarized potential with no change in the slope factor. Cumulative inactivation for I(K(DR)) was enhanced in the presence of ACO. In Jurkat cells incubated with amiloride (30 μM), the ACO-induced inhibition of I(K(DR)) remained unaltered. In RAW 264.7 murine macrophages, ACO did not modify the kinetics of I(K(DR)), although it suppressed I(K(DR)) amplitude. Taken together, these effects can significantly contribute to its action on functional activity of immune cells if similar results are found in vivo.

Effect of Berberine on Cell Survival in the Developing Rat Brain Damaged by MK-801

Berberine is an isoquinoline alkaloid isolated from goldenthread, Coptidis Rhizoma and shown to have many biological and pharmacological effects. We previously reported that berberine promotes cell survival and differentiation of neural stem cells. To examine whether berberine has survival promoting effect on damaged neuronal cells, we generated a cellular model under oxidative stress and an neonatal animal model of degenerating brain disease by injecting MK-801. MK801, a noncompetitive antagonist of N-methyl-d-aspartate (NMDA) receptors, acts as a neurotoxin in developing rats by inhibiting NMDA receptors and induce neuronal cell death. We found that the survival rate of the SH-SY5Y cells under oxidative stress was increased by 287% and 344%, when treated with 1.5 and 3.0µg/ml berberine, respectively. In the developing rats injected by MK801, we observed that TUNEL positive apoptotic cells were outspread in entire brain. The cell death was decreased more than 3 fold in the brains of the MK-801-induced neurodegenerative animal model when berberine was treated to the model animals. This suggests that berberine promotes activity dependent cell survival mediated by NMDA receptor because berberine is known to activate neurons by blocking K(+) current or lowering the threshold of the action potential. Taken together, berberine has neuroprotective effect on damaged neurons and neurodegenerating brains of neonatal animal model induced by MK-801 administration.

Berberine possesses muscarinic agonist-like properties in cultured rodent cardiomyocytes

Berberine, a natural product alkaloid, has been shown to display a wide array of pharmacological effects. Generally, the mechanism of action of each of these effects has not been well described. The aim of the present study is to test the hypothesis that some of berberine's cardiovascular effects are mediated through activation of cardiac M2 muscarinic cholinergic receptors. In our studies, we tested the ability of berberine to alter the contraction rate of cultured neonatal rodent cardiomyocytes. In these spontaneously contracting primary cultured cells, berberine reduced the contraction rate in a manner independent of β-adrenergic receptor blockade but sensitive to pertussis toxin, a Gi/o G protein inhibitor. Muscarinic antagonists completely blocked the effect of berberine on contraction rate of cardiomyocytes, whereas the effect of berberine was not opposed by antagonists to opioid, adenosine or α-adrenergic receptors. Further, berberine bound to muscarinic receptors of adult mouse heart membranes with relatively high affinity (K(i)=5.4×10(-6)M) comparable to that of the classic muscarinic agonist, carbachol, and to muscarinic M2 receptors exogenously expressed in HEK 293 cells (K(i)=4.9×10(-6)M). Therefore, the findings of the present study suggest that berberine is a muscarinic agonist at M2 receptors, potentially explaining some of its reported cardiovascular effects.

A systematic review of the anticancer properties of berberine, a natural product from Chinese herbs

Natural products represent a rich reservoir of potential small chemical molecules exhibiting antiproliferation and anticancer properties. An example is berberine, a protoberberine alkaloid widely distributed in medical plants used in traditional Chinese prescriptions. Recent advances have shown that berberine exerts anticancer activities both in vitro and in vivo through different mechanisms. Berberine shows inhibitory effects on the proliferation and reproduction of certain tumorigenic microorganisms and viruses, such as Heliobacter pylori and hepatitis B virus. Transcriptional regulation of some oncogene and carcinogenesis-related gene expression and interaction with both DNA and RNA are also well documented. Besides, berberine is a broad spectrum enzyme inhibitor, which affects N-acetyltransferase, cyclooxygenase-2, and topoisomerase activities and gene/protein expression. These actions, together with the regulation of reactive oxygen species production, mitochondrial transmembrane potential, and nuclear factor-kappaB activation might underlie its antiproliferative and proapoptotic effects. More importantly, the suppression of tumor growth and metastasis, the beneficial application in combined medication, and the improvement of multidrug resistance both in vivo and in vitro clearly show its potential as an alternative medicine for tumor chemotherapy.

Pharmacological and therapeutic effects of Berberis vulgaris and its active constituent, berberine

Barberry (Berberis vulgaris L. family Berberidaceae) is well known in Iran and various parts of this plant including its root, bark, leaf and fruit have been used as folk medicine. The two decades of research has demonstrated different pharmacological and therapeutic effects of B. vulgaris and its isoquinoline alkaloids (particularly berberine). Studies carried out on the chemical composition of the plant show that the most important constituents of this plant are isoquinoline alkaloids such as berberine, berbamine and palmatine. Berberine represents one of the most studied among the naturally occurring protoberberine alkaloids. In addition to B. vulgaris (barberry), berberine is present in many other plants and is used for the treatment of different diseases. This article reviews the traditional uses and pharmacological effects of total extract and the most active ingredient of B. vulgaris (berberine).

Downregulated NM23-H1 expression is associated with intracranial invasion of nasopharyngeal carcinoma

Because the focus of nasopharyngeal carcinoma (NPC) is very close to intracranial organs, it often makes incursions into cranial cavity. Identification of intracranial invasion-associated indicators will provide potential therapeutic targets for NPC patients with intracranial invasion. In this regard, Human Xpro™ HC-plus cancer-related gene chip was utilised to screen intracranial invasion-associated genes for NPC from the biopsied primary focus tissue samples. In all, 8 upregulated and 23 downregulated genes were obtained. VEGF165 and MMP-9, the two upregulated genes, and NM23-H1, the downregulated one, were further confirmed by immunohistochemistry, quantitative real-time PCR and western blot. Invasion-associated cellular and nude mouse models were subsequently employed to study the biological properties of NM23-H1. NM23-H1 expression was significantly lower in 5-8F cells compared with that in 6-10B cells. Moreover, patch-clamp and transwell chamber were adopted to investigate the invading potential-associated biological dynamic mechanisms in the two cell lines, and Ca²⁺ current and motility were significantly elevated in 5-8F cells compared with that in 6-10B cells. Berberine, an inhibitor of Ca²⁺ current, could substantially increase the expression of NM23-H1 and decrease 5-8F cell motility. The specificity of berberine on NM23-H1 and cell motility was confirmed by RNAi assay.

Activation of the aryl hydrocarbon receptor by berberine in HepG2 and H4IIE cells: Biphasic effect on CYP1A1

Berberine has long been considered a candidate for an antimalarial drug. It exerts a plethora of biological activities and has been used in the treatment of diarrhea and gastro-enteritis for centuries. Here we provide evidence that berberine activates the aryl hydrocarbon receptor (AhR) in human hepatoma (HepG2) and rat hepatoma cells stably transfected with a dioxin responsive element fused to the luciferase gene (H4IIE.luc). AhR was activated by high doses of berberine (10-50 microM) after 6 and 24 h of incubation as revealed by CYP1A1 mRNA expression (HepG2) and AhR-dependent luciferase activity (H4IIE.luc). Berberine induced nuclear translocation of AhR-GFP chimera transiently transfected to Hepa1c1c7 cells. In contrast, low doses of berberine (<1 microM) and prolonged times of the treatments (48 h) failed to produce any activation of AhR in H4IIE.luc cell line. HPLC analysis ruled out the hypothesis that the loss of berberine capacity to activate AhR in H4IIE.luc cells is due to metabolic inactivation of the alkaloid. We demonstrate that berberine is a potent inhibitor (IC50=2.5 microM) of CYP1A1 catalytic activity (EROD) in HepG2 cell culture and in recombinant CYP1A1 protein. Collectively, our results imply that while berberine activates the Ah receptor, it is accompanied by inactivation of the catalytic activity of CYP1A1 and occurs at concentrations that exceed those predicted to occur in vivo. Given these data, it appears that activation of the AhR pathway by berberine has a low toxicological potential.

Cytotoxic effect and electrophysiological activity of S-irniine, a synthesised isomer of the natural R-irniine, on human MRC-5 fibroblasts

Numerous original alkaloids are present in tubers of Arisarum vulgare Targ. a species belonging to the Araceae family known in Morocco for its toxicity. Some previous works deal with the activity of these natural compounds as R-irniine. As the enantioselective total synthesis of irniine has been realised, the R- and S-forms were obtained and this last one could be tested. Thus, a study of the cytotoxicity and the electrophysiological activity of S-irniine was carried out on human MRC-5 fibroblasts. A cytotoxic effect of S-irniine at 40 microg/mL was detected on MRC-5 fibroblasts. An electrophysiological study was also carried out on the MRC-5 cells by using the patch-clamp technique and no effect of this compound at this concentration on the outward potassium current of MRC-5 fibroblasts was observed. Thus, this study showed, as it was for R-irniine, that the cytotoxicity of S-irniine was not explained by an effect on the potassium currents.

Cytotoxic effect and electrophysiological study on human MRC-5 fibroblasts of R-irniine, a natural alkylpyrrolidine alkaloid

R-irniine is a natural 2-alkylpyrrolidine alkaloid extracted from Arisarum vulgare Targ., a species belonging to the Araceae family known in Morocco for its toxicity. Cytotoxic and electrophysiological studies of this compound on human MRC-5 fibroblasts were carried out. Cytotoxic potential of R-irniine was detected on MRC-5 fibroblasts at 40 microg/mL. We carried out the electrophysiological study of this compound on MRC-5 cells by using the technique of patch-clamp in "Whole cell" configuration. R-irniine showed no effect on the outward potassium current of the MRC-5 fibroblasts.

Inhibitory action of ICI-182,780, an estrogen receptor antagonist, on BK(Ca) channel activity in cultured endothelial cells of human coronary artery

ICI-182,780 is known to be a selective inhibitor of the intracellular estrogen receptors. The effect of ICI-182,780 on ion currents was studied in cultured endothelial cells of human coronary artery. In whole-cell current recordings, ICI-182,780 reversibly decreased the amplitude of K(+) outward currents. The decrease in outward current caused by ICI-182,780 could be counteracted by further application of magnolol or nordihydroguaiaretic acid, yet not by 17beta-estradiol. Under current-clamp condition, ICI-182,780 (3microM) depolarized the membrane potentials of the cells, and magnolol (10 microM) or nordihydroguaiaretic acid (10 microM) reversed ICI-182,780-induced depolarization. In inside-out patches, ICI-182,780 added to the bath did not alter single-channel conductance of large-conductance Ca(2+)-activated K(+) channels (BK(Ca) channels), but decreased their open probability. ICI-182,780 reduced channel activity in a concentration-dependent manner with an IC(50) value of 3 microM. After BK(Ca) channel activity was suppressed by 2-methoxyestradiol (3 microM), subsequent application of ICI-182,780 (3 microM) did not further reduce the channel activity. The application of ICI-182,780 shifted the activation curve of BK(Ca) channels to positive potentials. Its decrease in the open probability primarily involved a reduction in channel open duration. ICI-182,780 also suppressed the proliferation of these endothelial cells with an IC(50) value of 2 microM. However, in coronary smooth muscle cells, a bell-shaped concentration-response curve for the ICI-182,780 effect on BK(Ca) channel activity was observed. This study provides evidence that ICI-182,780 can inhibit BK(Ca) channels in vascular endothelial cells in a mechanism unlikely to be linked to its anti-estrogen activity. The inhibitory effects on these channels may partly contribute to the underlying mechanisms by which ICI-182,780 affects endothelial function.

Effect of arvanil (N-arachidonoyl-vanillyl-amine), a nonpungent anandamide-capsaicin hybrid, on ion currents in NG108-15 neuronal cells

The effects of arvanil (N-arachidonoyl-vanillyl-amine), a structural hybrid between capsaicin and anandamide, on ion currents in a mouse neuroblastoma and rat glioma hybrid cell line, NG108-15, were examined with the aid of the whole-cell voltage-clamp technique. Arvanil (0.2-50 microM) caused an inhibition of voltage-dependent L-type Ca(2+) current (I(Ca,L)) in a concentration-dependent manner. Arvanil produced no change in the overall shape of the current-voltage relationship of I(Ca,L). The IC(50) value of arvanil-induced inhibition of I(Ca,L) was 2 microM. Arvanil (5 microM) could shift the steady-state inactivation curve of I(Ca,L) to a more negative potential by approximately -15mV. No effect of arvanil (20 microM) on delayed rectifier K(+) current (I(K(DR))) was observed; however, capsaicin (20 microM), glyceryl nonivamide (20 microM) and capsinolol (20 microM) suppressed it significantly. Arvanil (20 microM) caused a slight reduction in the amplitude of erg (ether-à-go-go-related)-mediated K(+) current (I(K(erg))) without modifying the activation curve of this current, while capsaicin and glyceryl nonivamide were more effective in suppressing I(K(erg)). Under current-clamp configuration, arvanil decreased the firing frequency of action potentials. Arvanil-mediated inhibition of I(Ca,L) appeared to be independent of its binding to either vanilloid or cannabinoid receptors. The channel-blocking properties of arvanil may, at least in part, contribute to the underlying mechanisms by which it affects neuronal or neuroendocrine function.

Cytotoxic effect and electrophysiological activity of (S)-bgugaine, an alkylpyrrolidine alkaloid against MRC-5 fibroblasts

(+)-S-bgugaine [1], is an alkaloid prepared by enantioselective synthesis. This alkaloid is an isomer of R-bgugaine [2], an alkaloid isolated from Arisarum vulgare, an Araceae toxic plant of Morocco. The cytotoxic effect and the electrophysiological activity of (+)-S-bgugaine [1] against MRC-5 fibroblasts of (+)-S-bgugaine 1, were studied. (+)-S-bgugaine [1] showed a cytotoxic potential at 40 microg/ml against these MRC-5 cells. The electrophysiological study on MRC-5 cells was carried out using the technique of patch-clamp and showed that the activity of compound 1 involved a reduction of outward potassic current at the concentration of 100 microM (28.1 microg/ml) and was accentuated by 200 microM (56.2 microg/ml). In this study we show that S-bgugaine [1], decreases the outward potassic current.

Inhibitory effect of Coptidis Rhizoma and berberine on the proliferation of human esophageal cancer cell lines

Our previous study demonstrated that the herbal medicine, Oren-to, had antitumor effects on esophageal cancer cells (ECCs) in vitro. The purpose of this study was to examine which of the seven constituents of Oren-to had antitumor effects on esophageal cancer cells. MTT assay showed that, of the seven constituents, only the aqueous extract of Coptidis Rhizoma had potent inhibitory effect on the proliferation of two types of ECC lines, YES-3 and YES-4. In addition, the proliferation of all six types of ECC lines (YES-1 to YES-6) was inhibited in a dose-dependent manner (P<0.001 for all), when co-cultured at each concentration of Coptidis Rhizoma for 72 h. The ID50 of Coptidis Rhizoma for YES-1 to YES-6 was 2.2 microg/ml, 3.0 microg/ml, 0.25 microg/ml, 2.8 microg/ml, 2.5 microg/ml, and 0.5 microg/ml, respectively, berberine, one of protoberberine components of Coptidis Rhizoma, showed potent antitumor effects on all six types of ECC lines as well as Coptidis Rhizoma. In addition, the ID50 of berberine showed a positive correlation with that of Coptidis Rhizoma in six types of ECC lines examined (r2 = 0.763, P = 0.023). Cell cycle analysis of Coptidis Rhizoma-treated cancer cells showed the accumulation of cells in the G0/G1 phase and relative decrease of the S phase. These results support the possibility that the use of Coptidis Rhizoma containing abundant berberine may be useful as one of alternative therapies for esophageal cancers.

Inhibition of Ca2+-activated K+ current by clotrimazole in rat anterior pituitary GH3 cells

The ionic mechanism of clotrimazole, an imidazole antimycotic P-450 inhibitor, was examined in rat anterior pituitary GH3 cells. In perforated-patch whole-cell recording experiments, clotrimazole reversibly caused an inhibition of the Ca2+-activated K+ current in a dose-dependent manner. The IC50 value of the clotrimazole-induced inhibition of I(K(Ca)) was 3 microM. In the outside-out configuration of single channel recording, application of clotrimazole (10 microM) into the bath medium did not change the single channel conductance of large conductance Ca2+-activated K+(BK(Ca)) channels, but it suppressed the channel activity significantly. The change in the kinetic behavior of BK(Ca) channels caused by clotrimazole in these cells is found to be due to a decrease in mean open time and an increase in mean closed time. Other structurally distinct P-450 inhibitors (e.g. ketoconazole or econazole) also effectively suppressed the amplitude of I(K(Ca)). Clotrimazole (10 microM) blocked both the inactivating and non-inactivating components of the voltage-dependent K+ outward current (I(K(V))), but it produced a slight reduction of L-type Ca2+ inward current (I(Ca,L)) without altering the current-voltage relationship of I(Ca,L). Clotrimazole (10 microM) also increased the firing rate of action potentials. These results provide direct evidence that clotrimazole is capable of suppressing the activity of BK(Ca) channel in GH3 cells. Because of the non-selective inhibitory effect of clotrimazole on I(K(Ca)) and I(K(V)), this inhibition is mainly, if not entirely, due to a direct channel blockade. Thus, the present study implies that the blockade of these ionic channels by clotrimazole would affect hormonal secretion and neuronal excitability.

Synthesis and cytotoxicity evaluation of some 8-hydroxyquinoline derivatives

Interest in Mannich bases of 8-hydroxyquinoline stems from reports of their high potency against human cancer cells. In the search for potential anticancer drug candidates, Mannich bases of 8-hydroxyquinoline (7-pyrrolidinomethyl-8-hydroxyquinoline, 7-morpholinomethyl-8-hydroxyquinoline, 7-piperidinomethyl-8-hydroxyquinoline and 7-diethylaminomethyl-8-hydroxyquinoline) were synthesised by reaction with various secondary amines and formaldehyde. They were prepared as hydrochlorides. The cytotoxic activity of 7-pyrrolidinomethyl-8-hydroxyquinoline, 7-morpholinomethyl-8-hydroxyquinoline and 7-diethylaminomethyl-8-hydroxyquinoline compounds in the National Cancer Institute in-vitro cancer cell line panel was determined. It was found that they exhibited substantial cytotoxic activity against leukaemia. The log concentration of 7-pyrrolidinomethyl-8-hydroxyquinoline, 7-morpholinomethyl-8-hydroxyquinoline and 7-diethylaminomethyl-8-hydroxyquinoline that inhibited 50% of 60 cell lines' growth were -4.81 M, -5.09 M and -5.35 M, respectively. Compound 7-pyrrolidinomethyl-8-hydroxyquinoline was selected for further in-vivo testing. The electrophysiological effect of 7-pyrrolidinomethyl-8-hydroxyquinoline also was tested in human myeloma cells (RPMI 8226). The outward current was voltage dependent, activating at -40 mV and believed to be the voltage-activated K+ current I(K(V)). 7-Pyrrolidinomethyl-8-hydroxyquinoline (1-30 microM) caused the inhibition of I(K(V)) in a concentration-dependent manner. The IC50 value of 7-pyrrolidinomethyl-8-hydroxyquinoline-induced inhibition of I(K(V)) is 23 microM. The GI50 value of 7-pyrrolidinomethyl-8-hydroxyquinoline-induced inhibition of cell growth is 14 microM. The results suggest that at least part of the cytotoxicity effect of 7-pyrrolidinomethyl-8-hydroxyquinoline on myeloma cells could be related to blockade of voltage-activated K+ channels.

Berberine inhibits ion transport in human colonic epithelia

The effects of berberine on ion transport in both human colonic mucosal epithelia and an intestinal epithelial cell line (T84) were examined. Berberine (concentration range 0-500 microM) reduced both basal and stimulated ion transport responses in human colonic mucosae in a manner which was non-specific for Ca2+ -or cAMP-mediated signals. Similarly, in cultured intestinal epithelial monolayers, berberine inhibited Ca2+ -and cAMP-mediated responses indicating an inhibitory activity directly at the level of the epithelium rather than an indirect effect through other mucosal element(s). Berberine did not alter the rate of generation of cAMP by adenylyl cyclase or the activity of protein kinase A, the effector enzyme of the cAMP pathway. Berberine inhibited carbachol-stimulated 86Rb+ efflux from T84 monolayers. Berberine also inhibited K+ conductance in apically-permeabilised re-sected mucosae. These results indicate i) that berberine exerts an anti-secretory action directly upon epithelial cells and ii) the mechanism of action may be at the level of blockade of K+ channels.