Department of Otorhinolaryngology-Head and Neck Surgery, The Second Affiliated Hospital of Harbin Medical University, Harbin 150001, China.
Molecules. 2011 Sep 27;16(10):8152-64. doi: 10.3390/molecules16108152.
In the present study, we investigated the mechanisms of chamaejasmine action on human HEp-2 larynx carcinoma cells, which possess constitutively active Akt. Results indicated that chamaejasmine showed more notable anticancer activity than apigenin against HEp-2, PC-3, NCI-H1975, HT-29 and SKOV-3. Moreover, chamaejasmine presented most significantly inhibition towards HEp-2, with IC₅₀ values of 1.92 µM. Treatment of HEp-2 cells with chamaejasmine (1-4 μM) resulted in significant dose-dependent decrease in Akt phosphorylation at Serine473. Chamaejasmine-mediated dephosphorylation of Akt resulted in inhibition of its kinase activity, which was confirmed by reduced phosphorylation of proapoptotic proteins BAD and glycogen synthase kinase-3, essential downstream targets of Akt. Inactivation of Akt seems to be associated with downregulation of insulin-like growth factor receptor 1 protein level and inhibition of its autophosphorylation upon chamaejasmine treatment. Exposure to chamaejasmine significantly induced caspase-9 and caspase-3 activity. In vivo, chamaejasmine intake through gavage resulted in inactivation of Akt and induction of apoptosis in HEp-2 tumors. These results suggest that Akt inactivation and dephosphorylation of BAD is a critical event, at least in part, in chamaejasmine-induced HEp-2 cells apoptosis.
在本研究中，我们研究了鸡麻素作用于具有持续激活 Akt 的人喉癌细胞（HEp-2 细胞）的机制。结果表明，鸡麻素对 HEp-2、PC-3、NCI-H1975、HT-29 和 SKOV-3 细胞的抗癌活性均明显强于芹菜素。此外，鸡麻素对 HEp-2 细胞的抑制作用最为显著，IC₅₀ 值为 1.92 μM。用鸡麻素（1-4 μM）处理 HEp-2 细胞，导致 Akt 在丝氨酸 473 位点的磷酸化显著剂量依赖性降低。鸡麻素介导的 Akt 去磷酸化导致其激酶活性受到抑制，这通过 Akt 的下游关键靶蛋白 BAD 和糖原合酶激酶-3 的磷酸化减少得到证实。Akt 的失活似乎与胰岛素样生长因子受体 1 蛋白水平的下调以及鸡麻素处理后其自身磷酸化的抑制有关。鸡麻素的暴露显著诱导了 caspase-9 和 caspase-3 的活性。在体内，通过灌胃摄入鸡麻素导致 Akt 的失活和 HEp-2 肿瘤细胞的凋亡诱导。这些结果表明，Akt 的失活和 BAD 的去磷酸化至少部分是鸡麻素诱导的 HEp-2 细胞凋亡的关键事件。
