A hydrolysate of poly-trans-[(2-carboxyethyl)germasesquioxane] (Ge-132) suppresses Cav3.2-dependent pain by sequestering exogenous and endogenous sulfide
Fumiko Sekiguchi,
Nene Koike,
Yasuhiro Shimada,
Kaho Sugimoto,
Hiroshi Masuda,
Takashi Nakamura,
Hiroaki Yamaguchi,
Genzoh Tanabe,
Shinsuke Marumoto,
Yoshihito Kasanami,
Maho Tsubota,
Tsuyako Ohkubo,
Shigeru Yoshida,
Atsufumi Kawabata
Affiliations
Fumiko Sekiguchi
Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Kowakae 3-4-1, Higashi-Osaka, 577-8502, Japan
Nene Koike
Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Kowakae 3-4-1, Higashi-Osaka, 577-8502, Japan
Yasuhiro Shimada
Asai Germanium Research Institute Co., Ltd., Suzuranoka, Hakodate, Hokkaido, 042-0958, Japan
Kaho Sugimoto
Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Kowakae 3-4-1, Higashi-Osaka, 577-8502, Japan
Hiroshi Masuda
Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Kowakae 3-4-1, Higashi-Osaka, 577-8502, Japan
Takashi Nakamura
Asai Germanium Research Institute Co., Ltd., Suzuranoka, Hakodate, Hokkaido, 042-0958, Japan
Hiroaki Yamaguchi
Yamagata University Graduate School of Medicine, Iida-nishi 2-2-2, Yamagata, 990-9585, Japan; Department of Pharmacy, Yamagata University Hospital, Iida-nishi 2-2-2, Yamagata, 990-9585, Japan
Genzoh Tanabe
Laboratory of Pharmaceutical Organic Chemistry, Faculty of Pharmacy, Kindai University, 3-4-1 Kowakae, Higashi-Osaka, 577-8502, Japan
Shinsuke Marumoto
Joint Research Center, Kindai University, 3-4-1 Kowakae, Higashi-Osaka, 577-8502, Japan
Yoshihito Kasanami
Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Kowakae 3-4-1, Higashi-Osaka, 577-8502, Japan
Maho Tsubota
Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Kowakae 3-4-1, Higashi-Osaka, 577-8502, Japan
Tsuyako Ohkubo
Division of Basic Medical Sciences and Fundamental Nursing, Faculty of Nursing, Fukuoka Nursing College, Fukuoka, 814-0193, Japan
Shigeru Yoshida
Department of Life Science, Faculty of Science and Engineering, Kindai University, 3-4-1 Kowakae, Higashi-Osaka, 577-8502, Japan
Atsufumi Kawabata
Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, Kowakae 3-4-1, Higashi-Osaka, 577-8502, Japan; Corresponding author. Laboratory of Pharmacology and Pathophysiology, Faculty of Pharmacy, Kindai University, 3-4-1 Kowakae, Higashi-Osaka, 577-8502, Japan.
Poly-trans-[(2-carboxyethyl)germasesquioxane] (Ge-132), an organogermanium, is hydrolyzed to 3-(trihydroxygermyl)propanoic acid (THGP) in aqueous solutions, and reduces inflammation, pain and cancer, whereas the underlying mechanisms remain unknown. Sulfides including H2S, a gasotransmitter, generated from l-cysteine by some enzymes including cystathionine-γ-lyase (CSE), are pro-nociceptive, since they enhance Cav3.2 T-type Ca2+ channel activity expressed in the primary afferents, most probably by canceling the channel inhibition by Zn2+ linked via coordinate bonding to His191 of Cav3.2. Given that germanium is reactive to sulfur, we tested whether THGP would directly trap sulfide, and inhibit sulfide-induced enhancement of Cav3.2 activity and sulfide-dependent pain in mice. Using mass spectrometry and 1H NMR techniques, we demonstrated that THGP directly reacted with sulfides including Na2S and NaSH, and formed a sulfur-containing reaction product, which decreased in the presence of ZnCl2. In Cav3.2-transfected HEK293 cells, THGP inhibited the sulfide-induced enhancement of T-type Ca2+ channel-dependent membrane currents. In mice, THGP, administered systemically or locally, inhibited the mechanical allodynia caused by intraplantar Na2S. In the mice with cyclophosphamide-induced cystitis and cerulein-induced pancreatitis, which exhibited upregulation of CSE in the bladder and pancreas, respectively, systemic administration of THGP as well as a selective T-type Ca2+ channel inhibitor suppressed the cystitis-related and pancreatitis-related visceral pain. These data suggest that THGP traps sulfide and inhibits sulfide-induced enhancement of Cav3.2 activity, leading to suppression of Cav3.2-dependent pain caused by sulfide applied exogenously and generated endogenously.
