Yue Grace Gar-Lee, Kin-Ming Lee Julia, Cheng Ling, Chung-Lap Chan Ben, Jiang Lei, Fung Kwok-Pui, Leung Ping-Chung, Bik-San Lau Clara
Institute of Chinese Medicine, Shatin, New Territories, Hong Kong, China.
Xenobiotica. 2012 Jun;42(6):562-70. doi: 10.3109/00498254.2011.645516. Epub 2012 Feb 21.
Multidrug resistance is a major problem in hepatocellular carcinoma. Hedyotiscone A, a compound isolated from Chinese herbal medicine Hedyotis corymbosa (HC, family Rubiaceae), was used as the chemical marker to distinguish between HC and an anticancer herb Hedyotis diffusa (HD) in our previous study. The present study aimed to investigate whether HA exhibited antiproliferative activities in multidrug-resistant hepatocellular carcinoma cells R-HepG2 and the parental cells HepG2 using MTT assay and [(3)H]-thymidine incorporation assay. Our results showed that HA could significantly inhibit cell proliferation in R-HepG2 and HepG2 (IC(50) = 43.7 and 56.3 µg/mL, respectively), but not in normal human liver cells WRL-68 (IC(50) > 100 µg/mL) cells, suggesting its selective cytotoxic effects. Besides, HA induced apoptosis in R-HepG2 cells, as confirmed by annexin-V & propidium iodide staining, and DNA fragmentation assay. The caspase cascade was activated as shown by a significant increase of cleaved caspases-3, -7 and -9 in HA-treated R-HepG2 cells. The activities and protein expression of P-glycoprotein as well as mRNA expression of MDR1 were also decreased in HA-treated R-HepG2 cells. Our study demonstrated for the first time the antiproliferative activities of hedyotiscone A in multidrug-resistant R-HepG2 cells. The findings revealed the potential of this compound in treating multidrug-resistant tumor.
多药耐药是肝细胞癌中的一个主要问题。在我们之前的研究中，从茜草科中草药伞房花耳草（HC）中分离出的化合物耳草烯醇A被用作化学标志物，以区分HC和抗癌草药白花蛇舌草（HD）。本研究旨在使用MTT法和[³H] - 胸腺嘧啶核苷掺入法，研究耳草烯醇A（HA）在多药耐药的肝癌细胞R - HepG2及其亲本细胞HepG2中是否具有抗增殖活性。我们的结果表明，HA能显著抑制R - HepG2和HepG2细胞的增殖（IC₅₀分别为43.7和56.3 μg/mL），但对正常人肝细胞WRL - 68细胞无抑制作用（IC₅₀ > 100 μg/mL），提示其具有选择性细胞毒性作用。此外，通过膜联蛋白V和碘化丙啶染色以及DNA片段化分析证实，HA诱导R - HepG2细胞凋亡。在HA处理的R - HepG2细胞中，裂解的半胱天冬酶 - 3、 - 7和 - 9显著增加，表明半胱天冬酶级联反应被激活。在HA处理的R - HepG2细胞中，P - 糖蛋白的活性和蛋白表达以及MDR1的mRNA表达也降低。我们的研究首次证明了耳草烯醇A在多药耐药的R - HepG2细胞中的抗增殖活性。这些发现揭示了该化合物在治疗多药耐药肿瘤方面的潜力。
