Biochemistry and Molecular Biology Unit, Department of System Biology, School of Medicine, University of Alcala, Madrid, Spain.
Cell Death Dis. 2013 May 2;4(5):e618. doi: 10.1038/cddis.2013.141.
Cannabinoids exert antiproliferative effects in a wide range of tumoral cells, including hepatocellular carcinoma (HCC) cells. In this study, we examined whether the PPARγ-activated pathway contributed to the antitumor effect of two cannabinoids, Δ9-tetrahydrocannabinol (THC) and JWH-015, against HepG2 and HUH-7 HCC cells. Both cannabinoids increased the activity and intracellular level of PPARγ mRNA and protein, which was abolished by the PPARγ inhibitor GW9662. Moreover, genetic ablation with small interfering RNA (siRNA), as well as pharmacological inhibition of PPARγ decreased the cannabinoid-induced cell death and apoptosis. Likewise, GW9662 totally blocked the antitumoral action of cannabinoids in xenograft-induced HCC tumors in mice. In addition, PPARγ knockdown with siRNA caused accumulation of the autophagy markers LC3-II and p62, suggesting that PPARγ is necessary for the autophagy flux promoted by cannabinoids. Interestingly, downregulation of the endoplasmic reticulum stress-related protein tribbles homolog 3 (TRIB3) markedly reduced PPARγ expression and induced p62 accumulation, which was counteracted by overexpression of PPARγ in TRIB3-knocked down cells. Taken together, we demonstrate for the first time that the antiproliferative action of the cannabinoids THC and JWH-015 on HCC, in vitro and in vivo, are modulated by upregulation of PPARγ-dependent pathways.
大麻素在广泛的肿瘤细胞中发挥抗增殖作用，包括肝癌 (HCC) 细胞。在这项研究中，我们研究了两种大麻素 Δ9-四氢大麻酚 (THC) 和 JWH-015 的 PPARγ 激活途径是否有助于它们对 HepG2 和 HUH-7 HCC 细胞的抗肿瘤作用。这两种大麻素都增加了 PPARγ mRNA 和蛋白的活性和细胞内水平，而这一作用被 PPARγ 抑制剂 GW9662 所阻断。此外，小干扰 RNA (siRNA) 的基因敲除以及 PPARγ 的药理学抑制作用降低了大麻素诱导的细胞死亡和细胞凋亡。同样，GW9662 完全阻断了大麻素在荷瘤 HCC 小鼠模型中的抗肿瘤作用。此外，siRNA 下调 PPARγ 导致自噬标记物 LC3-II 和 p62 的积累，表明 PPARγ 是大麻素促进的自噬通量所必需的。有趣的是，内质网应激相关蛋白 tribbles 同源物 3 (TRIB3) 的下调显著降低了 PPARγ 的表达并诱导了 p62 的积累，而在 TRIB3 敲低细胞中过表达 PPARγ 则逆转了这一现象。总之，我们首次证明了大麻素 THC 和 JWH-015 在 HCC 中的体外和体内的抗增殖作用是通过上调 PPARγ 依赖性途径来调节的。
