硫化氢合成酶抑制剂金丝桃素的体内外抗结肠癌作用研究

为研究金丝桃素对硫化氢合成酶活性的影响,探索金丝桃素作为胱硫醚-β-合成酶(CBS)抑制剂的体内外抗结肠癌作用。本研究通过亚甲蓝法测定金丝桃素和氨基氧乙酸(AOAA)对CBS产H2S活性的抑制作用,以HT29人结肠癌细胞和移植HT29细胞的裸鼠肿瘤模型为抗肿瘤研究对象,测定金丝桃素体内外抗肿瘤作用。结果表明,来源于贯叶连翘(Hypericum perforatum L.)的化合物金丝桃素是CBS的高效选择性抑制剂,其IC50为7.9±1.42μmol/L。金丝桃素能显著抑制HT29人结肠癌细胞的增殖,其IC50为22.2±2.25μmol/L。基因沉默实验表明CBS蛋白可能是金丝桃素在细胞内的潜在靶标之一。意外的是,目前普遍使用的CBS抑制剂AOAA抑制HT29细胞增殖作用非常弱,其IC50为152.5±35.68μmol/L。此外,不同剂量的金丝桃素(5~30mg/kg·d)均能显著减少裸鼠肿瘤体积和重量,30mg/kg·d剂量皮下给药2周后,和对照组相比肿瘤重量减少了68%。以上结果表明金丝桃素作为CBS的选择性抑制剂具有显著的抗结肠癌作用。

Potent in vitro and in vivo antitumor effects of hydrogen sulfide producing enzyme inhibitor hypericin in colon cancer cells

To investigate the effect of hypericin on the activity of hydrogen sulfide producing enzyme and explore the antitumor effects of hypericin as a cystathionine-β-synthase (CBS) inhibitor in vitro and in vivo,the inhibitory effect of hypericin and aminooxyacetic acid (AOAA) on CBS activity was determined by the methylene blue method.Further,HT29 human colon cancer cells and a HT-29 colon cancer xenograft mouse model were used to study the antitumor effect of hypericin in vitro and in vivo.The results indicated that hypericin,a photosensitizer in the diagnosis and photodynamic therapy of cancer isolated from medicinal herb Hypericum perforatum,was identified as a potent and selective inhibitor of CBS with an IC 50 value of 7.9 ± 1.42 μmol/L.Hypericin greatly suppressed the proliferation of HT29 human colon cancer cells with an IC 50 value of 22.2 ± 2.25 μmol/L,and CBS protein could be one of the targets of hypericin in mammalian cells,as evidenced by CBS knockdown analyses.Surprisingly,AOAA,a commonly used CBS inhibitor,displayed very weak inhibition of HT29 cancer cells with an IC 50 value of 152.5 ± 35.68 μmol/L.This could perhaps be attributed to limited cell membrane permeability of AOAA.Additionally,hypericin at a dose of 5-30 mg/kg·d significantly inhibited the growth of xenograft tumors compared to the control group.After subcutaneous administration of 30 mg/kg·d for two weeks,the weight of the tumors decreased by 68% compared with the control group.Collectively,these results show that hypericin as a selective inhibitor of CBS has significant anti-colon cancer activity.