Yu Jun, Qiao Liang, Zimmermann Lars, Ebert Matthias P A, Zhang Hongxia, Lin Wendy, Röcken Christoph, Malfertheiner Peter, Farrell Geoffrey C
Storr Liver Unit, Westmead Millennium Institute, University of Sydney, Westmead Hospital, Westmead, NSW 2145, Australia.
Hepatology. 2006 Jan;43(1):134-43. doi: 10.1002/hep.20994.
Peroxisome proliferator-activated receptor gamma (PPARgamma) has been implicated in the differentiation and growth inhibition of cancer cells. We examined the effects of PPARgamma activation by troglitazone on hepatocellular carcinoma (HCC) cell growth, proliferation, and apoptosis in vitro and in vivo. We also studied relationships between PPARgamma activation and cyclooxygenase-2 (COX-2) expression. Human HCC cell lines Huh7 and Hep3B were cultured in the presence or absence of troglitazone. Cell growth was determined via WST-1 assay, proliferation by cell cycle analysis and proliferating cell nuclear antigen (PCNA) Western blotting, and apoptosis by flow cytometry and TUNEL. Tumor growth after subcutaneous implantation of Huh7 cells in nude mice was monitored, and the effects of treatment with troglitazone were determined. In resected HCCs, PPARgamma expression was less compared with the histologically normal surrounding liver. In cultures of Hep3B and Huh7 cells, basal expression of PPARgamma was relatively low, but troglitazone caused dose-dependent induction of PPARgamma expression. Cell cycle analysis revealed a decreased proportion of cells in S phase, with arrest at G0/G1. Concomitant downregulation of PCNA and an increase in TUNEL staining, cells were consistent with decreased proliferation and induction of apoptosis by troglitazaone. Troglitazone-mediated PPARgamma activation also suppressed COX-2 expression and induced p27 in HCC cells. Administration of troglitazone to Huh7 tumor-bearing mice significantly reduced tumor growth and caused tumor regression. In conclusion, collectively, these results indicate that PPARgamma could be a regulator of cell survival and growth in HCC. PPARgamma therefore represents a putative molecular target for chemopreventive therapy or inhibition of liver cancer growth.
过氧化物酶体增殖物激活受体γ（PPARγ）与癌细胞的分化和生长抑制有关。我们研究了曲格列酮激活PPARγ对体外和体内肝癌（HCC）细胞生长、增殖和凋亡的影响。我们还研究了PPARγ激活与环氧合酶-2（COX-2）表达之间的关系。人肝癌细胞系Huh7和Hep3B在有或无曲格列酮的情况下进行培养。通过WST-1法测定细胞生长，通过细胞周期分析和增殖细胞核抗原（PCNA）免疫印迹法测定增殖，通过流式细胞术和TUNEL法测定凋亡。监测裸鼠皮下植入Huh7细胞后的肿瘤生长，并确定曲格列酮治疗的效果。在切除的肝癌组织中，与组织学正常的周围肝脏相比，PPARγ表达较低。在Hep3B和Huh7细胞培养物中，PPARγ的基础表达相对较低，但曲格列酮导致PPARγ表达呈剂量依赖性诱导。细胞周期分析显示S期细胞比例降低，停滞在G0/G1期。PCNA同时下调，TUNEL染色增加，表明曲格列酮可降低细胞增殖并诱导细胞凋亡。曲格列酮介导的PPARγ激活还抑制了HCC细胞中COX-2的表达并诱导p27表达。给荷Huh7肿瘤的小鼠施用曲格列酮可显著降低肿瘤生长并导致肿瘤消退。总之，这些结果共同表明PPARγ可能是肝癌细胞存活和生长的调节因子。因此，PPARγ代表了化学预防治疗或抑制肝癌生长的一个假定分子靶点。
