Abstract
Triptolide (Trip), a diterpene triepoxide isolated from medicinal vine Trypterygium wilfordii Hook. F. possessed multiple biological activities including antineoplastic actions. However, no report concerning its effects on ion currents has been published. In this study, we attempted to determine whether this compound has any effects on ion currents in malignant glioma cells. The mRNA expression of KCNJ10 (Kir4.1) was detected in U373 glioma cells. The inwardly rectifying K+ currents (IK(IR)) in U373 cells were almost fully blocked by BaCl2 (1 mM). Trip (30 nM-10 μM) effectively decreased the amplitude of IK(IR) in a concentration-dependent manner with an IC50 value of 0.72 μM. In chlorotoxin-treated U373 cells, Trip-mediated block of IK(IR) remained effective. Addition of Trip (3 μM) slightly inhibited the amplitude of Ca2+-activated K+ current and sustained K+ outward current in U373 cells. In cell-attached configuration, when Trip was added to the bath, the activity of inwardly rectifying K+ (Kir) channels diminished with no change in single-channel conductance. Its suppression of Kir channels was accompanied by a reduction in the slow component of mean open time. Under current-clamp conditions, addition of Trip depolarized the membrane along with changes in frequency histogram of resting potential. Block by this component of Kir4.1 channels may be an important mechanism underlying its actions on the functional activity of glioma cells. Targeting at Kir4.1 channels may be clinically useful as an adjunctive regimen to anti-cancer drugs.
| Original language | English |
|---|---|
| Pages (from-to) | 332-341 |
| Number of pages | 10 |
| Journal | European Journal of Pharmacology |
| Volume | 738 |
| DOIs | |
| Publication status | Published - 2014 Sep 5 |
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All Science Journal Classification (ASJC) codes
- Pharmacology
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High effectiveness of triptolide, an active diterpenoid triepoxide, in suppressing Kir-channel currents from human glioma cells. / Cheung So, Edmund; Lo, Yi Ching; Chen, Li Tzong; Kao, Chin An; Wu, Sheng Nan.
In: European Journal of Pharmacology, Vol. 738, 05.09.2014, p. 332-341.Research output: Contribution to journal › Article
TY - JOUR
T1 - High effectiveness of triptolide, an active diterpenoid triepoxide, in suppressing Kir-channel currents from human glioma cells
AU - Cheung So, Edmund
AU - Lo, Yi Ching
AU - Chen, Li Tzong
AU - Kao, Chin An
AU - Wu, Sheng Nan
PY - 2014/9/5
Y1 - 2014/9/5
N2 - Triptolide (Trip), a diterpene triepoxide isolated from medicinal vine Trypterygium wilfordii Hook. F. possessed multiple biological activities including antineoplastic actions. However, no report concerning its effects on ion currents has been published. In this study, we attempted to determine whether this compound has any effects on ion currents in malignant glioma cells. The mRNA expression of KCNJ10 (Kir4.1) was detected in U373 glioma cells. The inwardly rectifying K+ currents (IK(IR)) in U373 cells were almost fully blocked by BaCl2 (1 mM). Trip (30 nM-10 μM) effectively decreased the amplitude of IK(IR) in a concentration-dependent manner with an IC50 value of 0.72 μM. In chlorotoxin-treated U373 cells, Trip-mediated block of IK(IR) remained effective. Addition of Trip (3 μM) slightly inhibited the amplitude of Ca2+-activated K+ current and sustained K+ outward current in U373 cells. In cell-attached configuration, when Trip was added to the bath, the activity of inwardly rectifying K+ (Kir) channels diminished with no change in single-channel conductance. Its suppression of Kir channels was accompanied by a reduction in the slow component of mean open time. Under current-clamp conditions, addition of Trip depolarized the membrane along with changes in frequency histogram of resting potential. Block by this component of Kir4.1 channels may be an important mechanism underlying its actions on the functional activity of glioma cells. Targeting at Kir4.1 channels may be clinically useful as an adjunctive regimen to anti-cancer drugs.
AB - Triptolide (Trip), a diterpene triepoxide isolated from medicinal vine Trypterygium wilfordii Hook. F. possessed multiple biological activities including antineoplastic actions. However, no report concerning its effects on ion currents has been published. In this study, we attempted to determine whether this compound has any effects on ion currents in malignant glioma cells. The mRNA expression of KCNJ10 (Kir4.1) was detected in U373 glioma cells. The inwardly rectifying K+ currents (IK(IR)) in U373 cells were almost fully blocked by BaCl2 (1 mM). Trip (30 nM-10 μM) effectively decreased the amplitude of IK(IR) in a concentration-dependent manner with an IC50 value of 0.72 μM. In chlorotoxin-treated U373 cells, Trip-mediated block of IK(IR) remained effective. Addition of Trip (3 μM) slightly inhibited the amplitude of Ca2+-activated K+ current and sustained K+ outward current in U373 cells. In cell-attached configuration, when Trip was added to the bath, the activity of inwardly rectifying K+ (Kir) channels diminished with no change in single-channel conductance. Its suppression of Kir channels was accompanied by a reduction in the slow component of mean open time. Under current-clamp conditions, addition of Trip depolarized the membrane along with changes in frequency histogram of resting potential. Block by this component of Kir4.1 channels may be an important mechanism underlying its actions on the functional activity of glioma cells. Targeting at Kir4.1 channels may be clinically useful as an adjunctive regimen to anti-cancer drugs.
UR - http://www.scopus.com/inward/record.url?scp=84927171769&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84927171769&partnerID=8YFLogxK
U2 - 10.1016/j.ejphar.2014.05.059
DO - 10.1016/j.ejphar.2014.05.059
M3 - Article
C2 - 24927992
AN - SCOPUS:84927171769
VL - 738
SP - 332
EP - 341
JO - European Journal of Pharmacology
JF - European Journal of Pharmacology
SN - 0014-2999
ER -