Doxorubicin selection for MDR1/P-glycoprotein reduces swelling-activated K+ and Cl- currents in MES-SA cells

1996 ◽  
Vol 270 (4) ◽  
pp. C1029-C1036 ◽  
Author(s):  
D. B. Luckie ◽  
M. E. Krouse ◽  
T. C. Law ◽  
B. I. Sikic ◽  
J. J. Wine
Keyword(s):  
Cell Line ◽  
Anion Channel ◽  
Uterine Sarcoma ◽  
Protein Levels ◽  
P Glycoprotein ◽  
Whole Cell Patch Clamp ◽  
Cl Channels ◽  
Line Selection ◽  
Selection For ◽  
K Currents

To test the hypothesis that P-glycoprotein enhances swelling currents through regulation of volume-sensitive Cl- channels [recently termed VSOAC (volume-sensitive osmolyte and anion channel)], a human uterine sarcoma cell line (MES-SA) and its doxorubicin-selected counterpart (Dx5) were studied. P-glycoprotein mRNA and protein levels were detected only in Dx5 cells. However, whole cell patch-clamp experiments showed that swollen Dx5 cells (n = 5) produced smaller VSOAC currents than MES-SA cells (n = 4; 106 +/- 26 pA/pF vs. 232 +/- 76 pA/pF at 90 mV). In radioisotopic efflux experiments, both swelling-activated 125I (Cl-) currents (n = 15) and 86Rb (K+) currents (n = 8) were found to be two-to fourfold smaller in the Dx5 (high P-glycoprotein) cells. Inhibitors of P-glycoprotein showed no specificity for the doxorubicin-selected cells (Dx5). Dideoxyforskolin (100 microM) blocked swelling-activated 125I efflux equally in both cell lines, whereas 100 microM verapamil had no effect. Thus, in this cell line, selection for P-glycoprotein expression is associated with reduced swelling currents. These findings suggest that P-glycoprotein expression does not directly facilitate VSOAC.

Selection for MDR1/P-glycoprotein enhances swelling-activated K+ and Cl- currents in NIH/3T3 cells

1994 ◽  
Vol 267 (2) ◽  
pp. C650-C658 ◽  
Author(s):  
D. B. Luckie ◽  
M. E. Krouse ◽  
K. L. Harper ◽  
T. C. Law ◽  
J. J. Wine
Keyword(s):  
Cell Lines ◽  
Response Curve ◽  
Drug Transport ◽  
Regulatory Volume Decrease ◽  
Absolute Difference ◽  
P Glycoprotein ◽  
Cl Channels ◽  
Selection For ◽  
Nih 3T3 ◽  
Cl Conductance

The relationship between multidrug resistance (MDR) P-glycoprotein expression and swelling-activated Cl- and K+ conductance was investigated in mouse NIH/3T3 fibroblasts and their colchicine-selected counterparts (COL1000, high P-glycoprotein). Whole cell patch-clamp and isotopic flux experiments confirmed that swelling-activated Cl- currents were induced by 20-30% bath dilution only in the MDR-expressing cell line. However, at bath dilutions > 30%, both cell lines developed Cl- currents that reached similar large magnitudes at higher dilution levels. Thus the apparent absolute difference in cell lines at lower dilutions is due to a shift in the response curve relating hypotonicity to Cl- conductance. At all dilutions and in both cell lines, the swelling-activated Cl- currents were outwardly rectifying, active at negative cell voltages, and inactivated at positive voltages. Verapamil (100 microM) and 1,9-dideoxyforskolin (100 microM), which inhibit P-glycoprotein drug transport, did not significantly inhibit the swelling-activated Cl- conductance efflux in the COL1000 cells also showed a leftward shift in the response curve to hypotonicity. These results indicate that response curve to hypotonicity. These results indicate that colchicine-selection for increased P-glycoprotein expression did not lead to the expression of swelling-activated Cl- channels, but instead enhanced a step in the pathway from bath dilution to regulatory volume decrease that is common to both K+ and Cl- channels.

scholarly journals Upregulations of Clcn3 and P-Gp Provoked by Lens Osmotic Expansion in Rat Galactosemic Cataract

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Lixia Ji ◽  
Lixia Cheng ◽  
Zhihong Yang
Keyword(s):  
Osmotic Stress ◽  
Early Stage ◽  
Lens Epithelial Cells ◽  
Anterior Capsule ◽  
Glycoprotein P ◽  
Protein Levels ◽  
P Glycoprotein ◽  
Sugar Cataract

Objective.Lens osmotic expansion, provoked by overactivated aldose reductase (AR), is the most essential event of sugar cataract. Chloride channel 3 (Clcn3) is a volume-sensitive channel, mainly participating in the regulation of cell fundamental volume, and P-glycoprotein (P-gp) acts as its modulator. We aim to study whether P-gp and Clcn3 are involved in lens osmotic expansion of galactosemic cataract.Methods and Results.In vitro, lens epithelial cells (LECs) were primarily cultured in gradient galactose medium (10–60 mM), more and more vacuoles appeared in LEC cytoplasm, and mRNA and protein levels of AR, P-gp, and Clcn3 were synchronously upregulated along with the increase of galactose concentration. In vivo, we focused on the early stage of rat galactosemic cataract, amount of vacuoles arose from equatorial area and scattered to the whole anterior capsule of lenses from the 3rd day to the 9th day, and mRNA and protein levels of P-gp and Clcn3 reached the peak around the 9th or 12th day.Conclusion. Galactosemia caused the osmotic stress in lenses; it also markedly leads to the upregulations of AR, P-gp, and Clcn3 in LECs, together resulting in obvious osmotic expansion in vitro and in vivo.

Correlation of expression levels of P-glycoprotein with resistance to adriamycin in a renal adenocarcinoma cell line

1997 ◽  
Vol 25 (6) ◽  
pp. 407-412
Author(s):  
S. Kawamoto ◽  
T. Deguchi ◽  
S. Nezasa ◽  
S. Yamada ◽  
M. Okano ◽  
...  
Keyword(s):  
Cell Line ◽  
Adenocarcinoma Cell Line ◽  
Adenocarcinoma Cell ◽  
Expression Levels ◽  
Renal Adenocarcinoma ◽  
P Glycoprotein

Establishment and characterization of an MDCK cell line stably-transfected with chicken Abcb1 encoding P-glycoprotein

2016 ◽  
Vol 106 ◽  
pp. 37-44 ◽  
Author(s):  
Yong Sun ◽  
Tingting Guo ◽  
Dawei Guo ◽  
Li Guo ◽  
Li Chen ◽  
...  
Keyword(s):  
Cell Line ◽  
Mdck Cell ◽  
Mdck Cell Line ◽  
P Glycoprotein
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