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Extracellular Guanosine and Guanine Nucleotides Decrease Viability of Human Breast Cancer SKBR-3 Cells
Ai Hotani1, Kazuki Kitabatake1, Mitsutoshi Tsukimoto1
1Department of Radiation Biosciences, Faculty of Pharmaceutical Sciences, Tokyo University of Science.
Abstract:
Though the physiological effects of adenosine and adenine nucleotides on purinergic receptors in cancer cells have been well studied, the influence of extracellular guanosine and guanine nucleotides on breast cancer cells remains unclear. Here, we show that extracellular guanosine and guanine nucleotides decrease the viability and proliferation of human breast cancer SKBR-3 cells. Treatment with guanosine or guanine nucleotides increased mitochondrial production of reactive oxygen species (ROS), and modified the cell cycle. Guanosine-induced cell death was suppressed by treatment with adenosine or the equilibrium nucleoside transporter (ENT) 1/2 inhibitor dipyridamole, but was not affected by adenosine receptor agonists or antagonists. These results suggest that guanosine inhibits adenosine uptake through ENT1/2, but does not antagonize adenosine receptors. In contrast, guanosine triphosphate (GTP)-induced cell death was suppressed not only by adenosine and dipyridamole, but also by the A1 receptor agonist 2-chloro-N6-cyclopentyladenosine (CCPA), suggesting that GTP-induced cell death is mediated in part by an antagonistic effect on adenosine A1 receptor. Thus, both guanosine and GTP induce apoptosis of breast cancer cells, but via at least partially different mechanisms.
Insights
Extracellular guanosine and guanine nucleotides reduce breast cancer cell viability and proliferation. Guanosine and guanosine triphosphate (GTP) induce apoptosis through distinct mechanisms, impacting reactive oxygen species and cell cycle progression.
Area of Science:
- Biochemistry
- Cell Biology
- Cancer Research
Background:
- Adenosine and adenine nucleotides' effects on cancer purinergic receptors are known.
- The impact of extracellular guanosine and guanine nucleotides on breast cancer cells is not well understood.
Purpose of the Study:
- To investigate the influence of extracellular guanosine and guanine nucleotides on human breast cancer SKBR-3 cells.
- To elucidate the mechanisms by which these compounds affect cancer cell viability, proliferation, and apoptosis.
Main Methods:
- Treatment of SKBR-3 cells with guanosine and guanine nucleotides.
- Assessment of cell viability, proliferation, mitochondrial reactive oxygen species (ROS) production, and cell cycle modification.
- Evaluation of the effects of adenosine, dipyridamole (ENT 1/2 inhibitor), and adenosine receptor agonists/antagonists on nucleotide-induced cell death.
Main Results:
- Extracellular guanosine and guanine nucleotides decreased SKBR-3 cell viability and proliferation.
- Nucleotide treatment increased mitochondrial ROS production and altered the cell cycle.
- Guanosine-induced cell death was inhibited by adenosine and dipyridamole, suggesting ENT1/2 inhibition, but not by adenosine receptor modulators.
- GTP-induced cell death was suppressed by adenosine, dipyridamole, and the A1 receptor agonist CCPA, indicating partial mediation via adenosine A1 receptor antagonism.
Conclusions:
- Both guanosine and GTP induce apoptosis in breast cancer cells.
- Guanosine and GTP appear to trigger apoptosis through at least partially different molecular mechanisms.
- Guanosine may inhibit adenosine uptake via ENT1/2, while GTP's effects involve partial antagonism of the adenosine A1 receptor.
