Inhibition of hypoxia-inducible carbonic anhydraseIX enhances hexokinase II inhibitor-induced hepatocellular carcinoma cell apoptosis

• Published in: 中国药理学报：英文版 2011, Vol.32 (7), p.912-920
• Main Author: Su-jongYU Jung-hwan YOON Jeong-hoon LEE Sun-jung MYUNG Eun-sun JANG Min-sun KWAK Eun-ju CHO Ja-june JANG Yoon-jun KIM Hyo-suk LEE
• Format: Article
• Language: English
• Subjects: HepG2细胞; 人肝癌细胞株; 己糖激酶; 碳酸酐酶; 细胞凋亡; 缺氧条件; 诱导; 酶抑制剂
• ISSN: 1671-4083; 1745-7254

Aim： The hypoxic condition within large or infiltrative hypovascular tumors produces intracellular acidification, which could activate many signaling pathways and augment cancer cell growth and invasion. Carbonic anhydrase-IX （CA-IX） is an enzyme lowering pH. This study is to examine whether hypoxia induces CA-IX in hepatocellular carcinoma （HCC） cells, and to evaluate its clinical implication in HCC patients. Methods： Human HCC cell lines （Huh-7 and HepG2 cells） were used, and cell growth was assessed using MTS assay. CA-IX expression and apoptotic/kinase signaling were evaluated using immunoblotting. The cells were transfected with CA-IX-specific siRNA, or treated with its inhibitor 4-（2-aminoethyl） benzenesulfonamide （CAI#1）, and/or the hexokinase II inhibitor, 3-bromopyruvate （3-BP）. A clinic pathological analysis of 69 patients who underwent an HCC resection was performed using a tissue array. Results： Incubation of HCC cells under hypoxia （1% 02, 5% C02, 94% N2） for 36 h significantly increased CA-IX expression level. CAI#1 （400 pmol/L） or CA-IX siRNA （100 pmol/L） did not influence HCC cell growth and induce apoptosis. However, CAI#1 or CA-IX siRNA at these concentrations enhanced the apoptosis induced by 3-BP （100 μmol/L）. This enhancement was attributed to increased ER stress and JNK activation, as compared with 3-BP alone. Furthermore, a clinic pathological analysis of 69 HCC patients revealed that tumor CA-IX intensity was inversely related to E-cadherin intensity. Conclusion： Inhibition of hypoxia-induced CA-IX enhances hexokinase ll inhibitor-induced HCC apoptosis. Furthermore, CA-IX expression profiles may have prognostic implications in HCC patients. Thus, the inhibition of CA-IX, in combination with a hexokinase ll inhibitor, may be therapeutically useful in patients with HCCs that are aggressively growing in a hypoxic environment.