TY - JOUR
T1 - Thymidine catabolism promotes NADPH oxidase-derived reactive oxygen species (ROS) signalling in KB and yumoto cells
AU - Tabata, Sho
AU - Yamamoto, Masatatsu
AU - Goto, Hisatsugu
AU - Hirayama, Akiyoshi
AU - Ohishi, Maki
AU - Kuramoto, Takuya
AU - Mitsuhashi, Atsushi
AU - Ikeda, Ryuji
AU - Haraguchi, Misako
AU - Kawahara, Kohichi
AU - Shinsato, Yoshinari
AU - Minami, Kentaro
AU - Saijo, Atsuro
AU - Toyoda, Yuko
AU - Hanibuchi, Masaki
AU - Nishioka, Yasuhiko
AU - Sone, Saburo
AU - Esumi, Hiroyasu
AU - Tomita, Masaru
AU - Soga, Tomoyoshi
AU - Furukawa, Tatsuhiko
AU - Akiyama, Shin Ichi
N1 - Funding Information:
We thank K. Endo, A. Ueno, K. Umetsu, K. Igarashi, H. Mitsuo, and T. Oka for technical assistance. We thank Drs. K. Miyadera, A. Tomoda, A. Nagashima, T. Nishihara, and T. Ishikawa for helpful discussions and insights, and Dr. Michael M. Gottesman for critical reading of the manuscript. This study was supported by Japan Society for the Promotion of Science KAKENHI (Grant Number; JP15K10338, JP26870456, JP16K07121, JP22501048, JP26870576, and JP16K21361), the Research Support Foundation of The University of Tokushima and TAIHO Pharmaceutical Co., Ltd., and the research funds from the Yamagata Prefecture Government and Tsuruoka City, Japan.
Publisher Copyright:
© 2018 The Author(s).
PY - 2018/12/1
Y1 - 2018/12/1
N2 - Thymidine phosphorylase (TP) is a rate-limiting enzyme in the thymidine catabolic pathway. TP is identical to platelet-derived endothelial cell growth factor and contributes to tumour angiogenesis. TP induces the generation of reactive oxygen species (ROS) and enhances the expression of oxidative stress-responsive genes, such as interleukin (IL)-8. However, the mechanism underlying ROS induction by TP remains unclear. In the present study, we demonstrated that TP promotes NADPH oxidase-derived ROS signalling in cancer cells. NADPH oxidase inhibition using apocynin or small interfering RNAs (siRNAs) abrogated the induction of IL-8 and ROS in TP-expressing cancer cells. Meanwhile, thymidine catabolism induced by TP increased the levels of NADPH and intermediates of the pentose phosphate pathway (PPP). Both siRNA knockdown of glucose 6-phosphate dehydrogenase (G6PD), a rate-limiting enzyme in PPP, and a G6PD inhibitor, dihydroepiandrosterone, reduced TP-induced ROS production. siRNA downregulation of 2-deoxy-D-ribose 5-phosphate (DR5P) aldolase, which is needed for DR5P to enter glycolysis, also suppressed the induction of NADPH and IL-8 in TP-expressing cells. These results suggested that TP-mediated thymidine catabolism increases the intracellular NADPH level via the PPP, which enhances the production of ROS by NADPH oxidase and activates its downstream signalling.
AB - Thymidine phosphorylase (TP) is a rate-limiting enzyme in the thymidine catabolic pathway. TP is identical to platelet-derived endothelial cell growth factor and contributes to tumour angiogenesis. TP induces the generation of reactive oxygen species (ROS) and enhances the expression of oxidative stress-responsive genes, such as interleukin (IL)-8. However, the mechanism underlying ROS induction by TP remains unclear. In the present study, we demonstrated that TP promotes NADPH oxidase-derived ROS signalling in cancer cells. NADPH oxidase inhibition using apocynin or small interfering RNAs (siRNAs) abrogated the induction of IL-8 and ROS in TP-expressing cancer cells. Meanwhile, thymidine catabolism induced by TP increased the levels of NADPH and intermediates of the pentose phosphate pathway (PPP). Both siRNA knockdown of glucose 6-phosphate dehydrogenase (G6PD), a rate-limiting enzyme in PPP, and a G6PD inhibitor, dihydroepiandrosterone, reduced TP-induced ROS production. siRNA downregulation of 2-deoxy-D-ribose 5-phosphate (DR5P) aldolase, which is needed for DR5P to enter glycolysis, also suppressed the induction of NADPH and IL-8 in TP-expressing cells. These results suggested that TP-mediated thymidine catabolism increases the intracellular NADPH level via the PPP, which enhances the production of ROS by NADPH oxidase and activates its downstream signalling.
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U2 - 10.1038/s41598-018-25189-y
DO - 10.1038/s41598-018-25189-y
M3 - Article
C2 - 29713062
AN - SCOPUS:85046337185
SN - 2045-2322
VL - 8
JO - Scientific Reports
JF - Scientific Reports
IS - 1
M1 - 6760
ER -
