Frese Steffen, Pirnia Farzaneh, Miescher Daniela, Krajewski Stan, Borner Markus M, Reed John C, Schmid Ralph A
Department of Clinical Research, Division of General Thoracic Surgery, University Hospital Berne, Switzerland.
Oncogene. 2003 Aug 21;22(35):5427-35. doi: 10.1038/sj.onc.1206842.
Tumor necrosis factor-related apoptosis-inducing ligand (Apo2L/TRAIL) belongs to the family of programmed cell death-inducing cytokines. Apo2L/TRAIL induces apoptosis in a wide variety of tumor cells. Tumor cells that are resistant to Apo2L/TRAIL-induced apoptosis can be sensitized by chemotherapeutic drugs and other agents via an unknown mechanism. Here we report that PG490 (triptolide), a diterpene triepoxide extracted from the Chinese herb Tripterygium wilfordii and used in traditional Chinese medicine, sensitizes lung cancer but not normal human bronchial epithelial cells to Apo2L/TRAIL-induced apoptosis. Sensitization was accompanied by caspase-3 and caspase-8 activation, whereas no cleavage of caspase-9 was observed. Determination of cell surface receptors by flow cytometry demonstrated no difference in Apo2L/TRAIL-R1 and -R2 expression, the two receptors with functional death domains, between resistant and sensitized cells. In cells treated with the combination of Apo2L/TRAIL and PG490, we observed activation of ERK2, a member of the mitogen-activated protein kinase family. Furthermore, sensitization could be blocked by the ERK inhibitor U0126 but not the p38 inhibitor SB203580, suggesting that activation of ERK2 is required for this effect. In addition, sensitization of lung cancer cells was also seen in ex vivo culture of lung cancer tissue from four patients who underwent surgery. Immunohistochemical staining showed a clear reduction in proliferation cell nuclear antigen (PCNA) in tissue treated with Apo2L/TRAIL and PG490. In conclusion, apoptosis induced by the combination of Apo2L/TRAIL and PG490 warrants further evaluation as a potential new strategy for the treatment of lung cancer.
肿瘤坏死因子相关凋亡诱导配体（Apo2L/TRAIL）属于诱导程序性细胞死亡的细胞因子家族。Apo2L/TRAIL可诱导多种肿瘤细胞凋亡。对Apo2L/TRAIL诱导的凋亡具有抗性的肿瘤细胞可被化疗药物和其他试剂通过未知机制使其敏感化。在此我们报告，PG490（雷公藤内酯醇），一种从中药雷公藤中提取的二萜环氧化合物，可使肺癌细胞而非正常人支气管上皮细胞对Apo2L/TRAIL诱导的凋亡敏感化。这种敏感化伴随着半胱天冬酶-3和半胱天冬酶-8的激活，而未观察到半胱天冬酶-9的裂解。通过流式细胞术测定细胞表面受体表明，在抗性细胞和敏感化细胞之间，具有功能性死亡结构域的两种受体Apo2L/TRAIL-R1和-R2的表达没有差异。在用Apo2L/TRAIL和PG490联合处理的细胞中，我们观察到有丝分裂原活化蛋白激酶家族成员ERK2的激活。此外，敏感化可被ERK抑制剂U0126阻断，但不能被p38抑制剂SB203580阻断，这表明ERK2的激活是产生这种效应所必需的。此外，在接受手术的4例患者的肺癌组织的体外培养中也观察到肺癌细胞的敏感化。免疫组织化学染色显示，在用Apo2L/TRAIL和PG490处理的组织中增殖细胞核抗原（PCNA）明显减少。总之，Apo2L/TRAIL和PG490联合诱导的凋亡作为一种潜在的肺癌治疗新策略值得进一步评估。
