The Apoptotic Effect of HIF-1α Inhibition Combined with Glucose plus Insulin Treatment on Gastric Cancer under Hypoxic Conditions.
Gastric cancer grows under a hypoxic environment. HIF-1α is known to play an important role in controlling the production of reactive oxygen species (ROS) in the mitochondria under hypoxic conditions. We previously established HIF-1α knockdown (KD) cells and control (SC) cells in the 58As9 gastric cancer cell line. In this study, we revealed that KD cells, but not SC cells, induced apoptosis under conditions of hypoxia (1% O2) due to excessive production of ROS. A quantitative RT-PCR analysis demonstrated that the expressions of ten genes, which are involved in the control mechanisms of ROS (including the Warburg effect, mitophagy, electron transport chain [ETC] modification and ROS scavenging), were regulated by HIF-1α. Moreover, the promotion of glucose uptake by glucose plus insulin (GI) treatment enhanced the apoptotic effect, which was accompanied by further ROS production in hypoxic KD cells. A Western blot analysis showed that the membranous expression of GLUT1 in KD cells was elevated by glucose and/or insulin treatments, indicating that the GI-induced glucose uptake is mediated by the increased translocation of GLUT1 on the cell membrane. Finally, the anti-tumor effect of HIF-1α knockdown (KD) plus GI was evaluated using a tumor xenograft model, where a hypoxic environment naturally exists. As a result, the GI treatment strongly inhibited the growth of the KD tumors whereby cell apoptosis was highly induced in comparison to the control treatment. In contrast, the growth of the SC tumors expressing HIF-1α was not affected by the GI treatment. Taken together, the results suggest that HIF-1α inhibition plus GI may be an ideal therapy, because the apoptosis due to the destruction of ROS homeostasis is specifically induced in gastric cancer that grows under a hypoxic environment, but not in the normal tissue under the aerobic conditions.
Department of Surgery, Saga University Faculty of Medicine, Nabeshima, Saga, Japan.
Tomokazu
T
Tanaka
Department of Surgery, Saga University Faculty of Medicine, Nabeshima, Saga, Japan; Department of Surgery, NHO Higashisaga Hospital, Harakoga, Miyaki-town, Miyaki-Gun, Saga, Japan.
Yoshihiko
Y
Kitajima
Department of Surgery, Saga University Faculty of Medicine, Nabeshima, Saga, Japan.
Shuusuke
S
Miyake
Division of Pathology, Research Center of Innovative Oncology, National Cancer Center Hospital East, Kashiwanoha, Kashiwa, Chiba, Japan.
Kazuyoshi
K
Yanagihara
Department of Immunology, Kagoshima University Graduate School of Medical and Dental Sciences, Sakuragaoka, Kagoshima, Japan.
Hiromitsu
H
Hara
Department of Molecular and Tumor Pathology, Akita University Graduate School of Medicine, Hondo, Akita, Japan.
Aki
A
Nishijima-Matsunobu
Department of Surgery, Saga University Faculty of Medicine, Nabeshima, Saga, Japan.
Koichi
K
Baba
Department of Surgery, Saga University Faculty of Medicine, Nabeshima, Saga, Japan.
Masaaki
M
Shida
Department of Surgery, Saga University Faculty of Medicine, Nabeshima, Saga, Japan.
Kota
K
Wakiyama
Department of Surgery, Saga University Faculty of Medicine, Nabeshima, Saga, Japan.
Jun
J
Nakamura
Department of Surgery, Saga University Faculty of Medicine, Nabeshima, Saga, Japan.
Hirokazu
H
Noshiro
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D005947:Glucose / Q000494:pharmacology*; D051272:Glucose Transporter Type 1 / Q000235:genetics / Q000378:metabolism; D006801:Humans; D000860:Hypoxia / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology*; D051379:Mice; D008819:Mice, Nude; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D010100:Oxygen / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000819:agonists / Q000378:metabolism; D015398:Signal Transduction; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
D051272:Glucose Transporter Type 1; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007328:Insulin; D009363:Neoplasm Proteins; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; C495677:SLC2A1 protein, human; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D005947:Glucose; D010100:Oxygen