Apoptosis-inducing antitumor efficacy of hexokinase II inhibitor in hepatocellular carcinoma.
Hypoxia stimulates hepatocellular carcinoma (HCC) cell growth via hexokinase (HK) II induction, and alternatively, HK II inhibition induces apoptosis by activating mitochondrial signaling. This study was to investigate whether the induction of HK II by hypoxia is associated with enhanced mitochondrial stability and to confirm the apoptosis-inducing efficacy of HK II inhibitor in an in vivo model of HCC. Mitochondrial stability was examined by treating isolated mitochondria with deoxycholate, a permeability-enhancing agent. Alteration of permeability transition pore complex composition was analyzed by immunoprecipitation and immunoblotting. An in vivo model of HCC was established in C3H mice i.d. implanted with MH134 cells. The antitumor efficacy of i.p. given 3-bromopyruvate (3-BrPA), a HK II inhibitor, was evaluated by measuring tumor volumes and quantifying apoptosis using terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining and (99m)Tc-hydrazinonicotinamide-Annexin V scans. Hypoxia enhanced mitochondrial stability, and this was inhibited by 3-BrPA treatment. In particular, HK II levels in permeability transition pore complex immunoprecipitates were reduced after 3-BrPA treatment. In mice treated with 3-BrPA, mean tumor volumes and tumor volume growth were found to be significantly reduced. Moreover, percentages of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive cells were significantly increased in 3-BrPA-treated mice, and this apoptosis-inducing efficacy was reflected in vivo by (99m)Tc-hydrazinonicotinamide-Annexin V imaging. Our results show that hypoxia enhances mitochondrial stability via HK II induction and that HK II inhibitor treatment exhibits an in vivo antitumor effect by inducing apoptosis. Therefore, HK II inhibitors may be therapeutically useful for the treatment of advanced infiltrative hypovascular HCCs, which are growing in a hypoxic environment.
Kim
Won
W
Department of Internal Medicine and Liver Research Institute, Seoul National University College of Medicine, Seoul, Korea.
Yoon
Jung-Hwan
JH
Jeong
Jae-Min
JM
Cheon
Gi-Jeong
GJ
Lee
Tae-Sup
TS
Yang
Jong-In
JI
Park
Su-Cheol
SC
Lee
Hyo-Suk
HS
D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D001389:Azirines; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000201:enzymology / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000493:pharmacokinetics / Q000494:pharmacology*; D005434:Flow Cytometry; D006593:Hexokinase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006801:Humans; D000860:Hypoxia; D015151:Immunoblotting; D047468:Immunoprecipitation; D008114:Liver Neoplasms, Experimental / Q000188:drug therapy* / Q000201:enzymology / Q000378:metabolism; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D010713:Phosphatidylcholines; D011768:Pyruvate Dehydrogenase Complex / Q000037:antagonists & inhibitors; D011773:Pyruvates / Q000493:pharmacokinetics / Q000494:pharmacology*; D014018:Tissue Distribution; D014407:Tumor Cells, Cultured
D017304:Annexin A5; D001389:Azirines; D004791:Enzyme Inhibitors; D010713:Phosphatidylcholines; D011768:Pyruvate Dehydrogenase Complex; D011773:Pyruvates; C017092:bromopyruvate; C039009:1-palmitoyl-2-(10-(4-((trifluoromethyl)diazirinyl)phenyl)-8-oxadecanoyl)-sn-glycero-3-phosphocholine; D006593:Hexokinase