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Distinct Cellular Calcium Metabolism in Radiation-sensitive RKO Human Colorectal Cancer Cells.

Kim YT, Jo SS, Park YJ, Lee MZ, Suh CK - Korean J. Physiol. Pharmacol. (2014)

Bottom Line: Thus, in this study, we investigated how cellular Ca(2+) metabolism in RKO cells, in comparison to radiation-resistant A549 cells, was altered by gamma (γ)-irradiation.In irradiated RKO cells, Ca(2+) influx via activation of NCX reverse mode was enhanced and a decline of [Ca(2+)]i via forward mode was accelerated.An increase in [Ca(2+)]i via SOCI was enhanced in irradiated RKO cells, while that in A549 cells was depressed.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology and Biophysics, Inha University College of Medicine, Incheon 401-751, Korea. ; Research Group of Food Functionality, Korea Food Research Institute, Seongnam 463-746, Division of Food Biotechnology, Korea University of Science and Technology, Daejeon 305-350, Korea.

ABSTRACT
Radiation therapy for variety of human solid tumors utilizes mechanism of cell death after DNA damage caused by radiation. In response to DNA damage, cytochrome c was released from mitochondria by activation of pro-apoptotic Bcl-2 family proteins, and then elicits massive Ca(2+) release from the ER that lead to cell death. It was also suggested that irradiation may cause the deregulation of Ca(2+) homeostasis and trigger programmed cell death and regulate death specific enzymes. Thus, in this study, we investigated how cellular Ca(2+) metabolism in RKO cells, in comparison to radiation-resistant A549 cells, was altered by gamma (γ)-irradiation. In irradiated RKO cells, Ca(2+) influx via activation of NCX reverse mode was enhanced and a decline of [Ca(2+)]i via forward mode was accelerated. The amount of Ca(2+) released from the ER in RKO cells by the activation of IP3 receptor was also enhanced by irradiation. An increase in [Ca(2+)]i via SOCI was enhanced in irradiated RKO cells, while that in A549 cells was depressed. These results suggest that γ-irradiation elicits enhancement of cellular Ca(2+) metabolism in radiation-sensitive RKO cells yielding programmed cell death.

No MeSH data available.


Related in: MedlinePlus

Effects of γ-irradiation on NCX in RKO and A549 cells. The activity of NCX in cells was measured in the reverse mode of NCX induced by superfusing 0 mM Na+/2.5 mM Ca2+ solution containing 1 µM thapsigargin (Thapsi), 5 mM caffeine (CAF), and 250 µM La3+ and in the forward mode of NCX by 140 mM Na+/0 mM Ca2+ solution. (A) In RKO control cells, R340/380 increased with the reverse mode of NCX and decreased with the forward mode. (B) In γ-ray irradiated RKO cells, the second peak was observed. The slope of R340/380 changes by the forward mode of NCX was increased in γ-rays irradiated cells. (C) In A549 control cells, R340/380 changed as in (A). (D) In γ-ray irradiated A549 cells, the slope of R340/380 changes by the forward mode of NCX was increased, confirming the activity of NCX was increased by γ-irradiation (p<0.0001). Tracings in (A) to (D) represent the average values of R340/380.
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Figure 1: Effects of γ-irradiation on NCX in RKO and A549 cells. The activity of NCX in cells was measured in the reverse mode of NCX induced by superfusing 0 mM Na+/2.5 mM Ca2+ solution containing 1 µM thapsigargin (Thapsi), 5 mM caffeine (CAF), and 250 µM La3+ and in the forward mode of NCX by 140 mM Na+/0 mM Ca2+ solution. (A) In RKO control cells, R340/380 increased with the reverse mode of NCX and decreased with the forward mode. (B) In γ-ray irradiated RKO cells, the second peak was observed. The slope of R340/380 changes by the forward mode of NCX was increased in γ-rays irradiated cells. (C) In A549 control cells, R340/380 changed as in (A). (D) In γ-ray irradiated A549 cells, the slope of R340/380 changes by the forward mode of NCX was increased, confirming the activity of NCX was increased by γ-irradiation (p<0.0001). Tracings in (A) to (D) represent the average values of R340/380.

Mentions: When the cells were superfused with 0 mM Na+/2.5 mM Ca2+ solution, as described in "METHODS", R340/380 in RKO cells increased to a plateau value (from 0.85±0.01 to 1.65±0.03) as shown in Fig. 1. Subsequent superfusion of 140 mM Na+/0 Ca2+ solution lowered R340/380 to the resting level with rate of R340/380 changes of -0.17±0.05 /min (Fig. 1A and Table 2). In γ-ray irradiated RKO cells, R340/380 increased to a plateau value (from 0.92±0.10 to 1.66±0.20) and an additional increase to 1.87±0.40 was followed. Subsequent superfusion of 140 mM Na+/0 mM Ca2+ solution lowered R340/380 to the resting level with rate of R340/380 changes of -0.25±0.10 /min (Fig. 1B and Table 2). The decay to the basal level of R340/380 in irradiated cells was completed faster than that of control cells (230 sec vs. 290 sec) (p<0.001).


Distinct Cellular Calcium Metabolism in Radiation-sensitive RKO Human Colorectal Cancer Cells.

Kim YT, Jo SS, Park YJ, Lee MZ, Suh CK - Korean J. Physiol. Pharmacol. (2014)

Effects of γ-irradiation on NCX in RKO and A549 cells. The activity of NCX in cells was measured in the reverse mode of NCX induced by superfusing 0 mM Na+/2.5 mM Ca2+ solution containing 1 µM thapsigargin (Thapsi), 5 mM caffeine (CAF), and 250 µM La3+ and in the forward mode of NCX by 140 mM Na+/0 mM Ca2+ solution. (A) In RKO control cells, R340/380 increased with the reverse mode of NCX and decreased with the forward mode. (B) In γ-ray irradiated RKO cells, the second peak was observed. The slope of R340/380 changes by the forward mode of NCX was increased in γ-rays irradiated cells. (C) In A549 control cells, R340/380 changed as in (A). (D) In γ-ray irradiated A549 cells, the slope of R340/380 changes by the forward mode of NCX was increased, confirming the activity of NCX was increased by γ-irradiation (p<0.0001). Tracings in (A) to (D) represent the average values of R340/380.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4296041&req=5

Figure 1: Effects of γ-irradiation on NCX in RKO and A549 cells. The activity of NCX in cells was measured in the reverse mode of NCX induced by superfusing 0 mM Na+/2.5 mM Ca2+ solution containing 1 µM thapsigargin (Thapsi), 5 mM caffeine (CAF), and 250 µM La3+ and in the forward mode of NCX by 140 mM Na+/0 mM Ca2+ solution. (A) In RKO control cells, R340/380 increased with the reverse mode of NCX and decreased with the forward mode. (B) In γ-ray irradiated RKO cells, the second peak was observed. The slope of R340/380 changes by the forward mode of NCX was increased in γ-rays irradiated cells. (C) In A549 control cells, R340/380 changed as in (A). (D) In γ-ray irradiated A549 cells, the slope of R340/380 changes by the forward mode of NCX was increased, confirming the activity of NCX was increased by γ-irradiation (p<0.0001). Tracings in (A) to (D) represent the average values of R340/380.
Mentions: When the cells were superfused with 0 mM Na+/2.5 mM Ca2+ solution, as described in "METHODS", R340/380 in RKO cells increased to a plateau value (from 0.85±0.01 to 1.65±0.03) as shown in Fig. 1. Subsequent superfusion of 140 mM Na+/0 Ca2+ solution lowered R340/380 to the resting level with rate of R340/380 changes of -0.17±0.05 /min (Fig. 1A and Table 2). In γ-ray irradiated RKO cells, R340/380 increased to a plateau value (from 0.92±0.10 to 1.66±0.20) and an additional increase to 1.87±0.40 was followed. Subsequent superfusion of 140 mM Na+/0 mM Ca2+ solution lowered R340/380 to the resting level with rate of R340/380 changes of -0.25±0.10 /min (Fig. 1B and Table 2). The decay to the basal level of R340/380 in irradiated cells was completed faster than that of control cells (230 sec vs. 290 sec) (p<0.001).

Bottom Line: Thus, in this study, we investigated how cellular Ca(2+) metabolism in RKO cells, in comparison to radiation-resistant A549 cells, was altered by gamma (γ)-irradiation.In irradiated RKO cells, Ca(2+) influx via activation of NCX reverse mode was enhanced and a decline of [Ca(2+)]i via forward mode was accelerated.An increase in [Ca(2+)]i via SOCI was enhanced in irradiated RKO cells, while that in A549 cells was depressed.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology and Biophysics, Inha University College of Medicine, Incheon 401-751, Korea. ; Research Group of Food Functionality, Korea Food Research Institute, Seongnam 463-746, Division of Food Biotechnology, Korea University of Science and Technology, Daejeon 305-350, Korea.

ABSTRACT
Radiation therapy for variety of human solid tumors utilizes mechanism of cell death after DNA damage caused by radiation. In response to DNA damage, cytochrome c was released from mitochondria by activation of pro-apoptotic Bcl-2 family proteins, and then elicits massive Ca(2+) release from the ER that lead to cell death. It was also suggested that irradiation may cause the deregulation of Ca(2+) homeostasis and trigger programmed cell death and regulate death specific enzymes. Thus, in this study, we investigated how cellular Ca(2+) metabolism in RKO cells, in comparison to radiation-resistant A549 cells, was altered by gamma (γ)-irradiation. In irradiated RKO cells, Ca(2+) influx via activation of NCX reverse mode was enhanced and a decline of [Ca(2+)]i via forward mode was accelerated. The amount of Ca(2+) released from the ER in RKO cells by the activation of IP3 receptor was also enhanced by irradiation. An increase in [Ca(2+)]i via SOCI was enhanced in irradiated RKO cells, while that in A549 cells was depressed. These results suggest that γ-irradiation elicits enhancement of cellular Ca(2+) metabolism in radiation-sensitive RKO cells yielding programmed cell death.

No MeSH data available.


Related in: MedlinePlus