Wu Zhen, Wu Li-Jun, Li Lin-Hao, Tashiro Shin-Ichi, Onodera Satoshi, Ikejima Takashi
Department of Pharmaceutical Science, Heilongjiang University, Harbin 150080, China.
J Asian Nat Prod Res. 2004 Sep;6(3):155-66. doi: 10.1080/1028602032000169622.
Shikonin, isolated from the plant Lithospermum erythrorhizon Sieb. ET Zucc, inhibited tumor cell growth and induced cell death in various tumor cells, with 50% growth inhibition of human cervical cancer cells, HeLa, at 18.9 +/- 1.1 mumol L-1. Treated with 40 mumol L-1 shikonin, HeLa cells underwent marked apoptotic morphological changes such as a round shape, membrane blebbing and apoptotic bodies derived from the fragmented nuclei. Another hallmark of apoptosis, DNA fragmentation, was observed by gel electrophoresis. Shikonin (10 mumol L-1) significantly blocked the transition from G1 to S phase in the HeLa cell cycle. Pan-caspase inhibitor (Z-VAD-FMK), caspase-3 inhibitor (Z-DEVD-FMK) or caspase-8 inhibitor (Z-IETD-FMK) effectively inhibited shikonin-induced cell death, while caspase-1 inhibitor (Ac-YVAD-CMK) and caspase-9 inhibitor (Z-LEHD-FMK) failed to affect cell death. Caspase-3 activity significantly increased within 12 h after shikonin treatment. Reduced expression of inhibitor of caspase-activated deoxyribonuclease (ICAD) after exposure to shikonin for 12 h suggests the resultant activation of caspase-activated deoxyribonuclease (CAD), leading to apoptosis.
紫草素是从植物紫草（Lithospermum erythrorhizon Sieb. ET Zucc）中分离得到的，它能抑制多种肿瘤细胞的生长并诱导细胞死亡，对人宫颈癌细胞HeLa的生长抑制率达到50%时的浓度为18.9±1.1 μmol/L。用40 μmol/L紫草素处理后，HeLa细胞出现明显的凋亡形态学变化，如细胞变圆、细胞膜起泡以及由破碎细胞核形成的凋亡小体。通过凝胶电泳观察到了凋亡的另一个标志——DNA片段化。紫草素（10 μmol/L）显著阻断了HeLa细胞周期中从G1期到S期的转变。泛半胱天冬酶抑制剂（Z-VAD-FMK）、半胱天冬酶-3抑制剂（Z-DEVD-FMK）或半胱天冬酶-8抑制剂（Z-IETD-FMK）能有效抑制紫草素诱导的细胞死亡，而半胱天冬酶-1抑制剂（Ac-YVAD-CMK）和半胱天冬酶-9抑制剂（Z-LEHD-FMK）则未能影响细胞死亡。紫草素处理后12小时内，半胱天冬酶-3的活性显著增加。暴露于紫草素12小时后，半胱天冬酶激活的脱氧核糖核酸酶（ICAD）表达降低，这表明半胱天冬酶激活的脱氧核糖核酸酶（CAD）被激活，从而导致细胞凋亡。
