Adenosine induces apoptosis in the human gastric cancer cells via an intrinsic pathway relevant to activation of AMP-activated protein kinase.
Extracellular adenosine significantly reduced cell viability in a dose (0.1-20mM)- and treatment time (24-72h)-dependent manner in GT3-TKB cells, a human gastric cancer cell line. Nuclei of cells were reactive to Hoechst 33342, a marker of apoptosis, and an anti-single-stranded DNA. Adenosine-induced GT3-TKB cell death was significantly inhibited by dipyridamole, an inhibitor of adenosine transporter, and 5'-amino-5'-deoxyadenosine, an inhibitor of adenosine kinase, but the effect was not affected by theophylline, a broad inhibitor of adenosine receptors, 8-cyclopentyltheophylline, an inhibitor of A(1) adenosine receptors or 3,7-dimethyl-1-propargylxanthine, an inhibitor of A(2a) adenosine receptors. Adenosine had no effect on mitochondrial membrane potentials. The effect of adenosine on GT3-TKB cell death was not inhibited by a pancaspase inhibitor or inhibitors of caspase-1,-3,-4,-8, and -9. 5-Aminoimidazole-4-carboxamide ribonucleoside (AICAR), an activator of AMP-activated protein kinase (AMPK), significantly reduced GT3-TKB cell viability, but the AICAR action was not reinforced in the presence of adenosine. The results of the present study, thus, suggest that extracellular adenosine induces apoptosis in GT3-TKB cells by its uptake into cells and conversion to AMP followed by activation of AMPK, regardless of caspase activation linked to the mitochondria and the endoplasmic reticulum.
Saitoh
Masaru
M
Department of Physiology, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya 663-8501, Japan.
Nagai
Kaoru
K
Nakagawa
Kazuhiko
K
Yamamura
Takehira
T
Yamamoto
Satoshi
S
Nishizaki
Tomoyuki
T
D000225:Adenine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000241:Adenosine / Q000494:pharmacology*; D000263:Adenylate Kinase / Q000378:metabolism*; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives* / Q000494:pharmacology*; D017209:Apoptosis; D061945:Caspase Inhibitors; D004176:Dipyridamole / Q000494:pharmacology; D004347:Drug Interactions; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D018047:Receptors, Purinergic P1; D012265:Ribonucleotides / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013274:Stomach Neoplasms / Q000473:pathology; D014407:Tumor Cells, Cultured
D061945:Caspase Inhibitors; D018047:Receptors, Purinergic P1; D012265:Ribonucleotides; D000620:Aminoimidazole Carboxamide; C010192:9-(2-hydroxy-3-nonyl)adenine; D004176:Dipyridamole; D000263:Adenylate Kinase; C031143:AICA ribonucleotide; D000225:Adenine; D000241:Adenosine