Guo Ying, Yuan Jin, Yin Shuqin, Wang Xiaoxia, Shuai Rong, Kang Jiali
*The First Affiliated Hospital of Jinan University; †Department of Gynecology and Obstetrics, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, Guangdong, China.
Int J Gynecol Cancer. 2017 Jul;27(6):1082-1087. doi: 10.1097/IGC.0000000000001003.
Paclitaxel is recommended as a first-line chemotherapeutic agent against ovarian cancer, but drug resistance becomes a major limitation. The key molecule or mechanism associated with paclitaxel resistance in ovarian cancer still remains unclear. Recent studies have revealed an association between autophagy and drug resistance.
We previously synthesized a MAPK kinase-recombinant fusion protein, MAP2K6-FP, that contains 3 domains: a protein transduction domain TAT, a human ovarian cancer HO8910 cell-specific binding peptide, and a potential antitumor effector domain MKK6(E). In this study, we investigated the effect of MAP2K6-FP on HO8910 cells treated with paclitaxel.
The IC50 (concentration by which 50% cell growth was inhibited) was 20 μM for paclitaxel alone, 1.5 μg/mL for MAP2K6-FP alone, and 0.3 μg/mL for MAP2K6-FP and 15 μM for paclitaxel if combined, respectively. In addition, immunohistochemistry assay demonstrated that tumor tissues from ovarian cancer patients showed higher expression of LC-3, the autophagy-related protein, compared with normal ovarian tissues. MAP2K6-FP (0, 2.5, 5, 10, 20, and 40 μg/mL) dose-dependently increased the LC-3 expression in HO8910 cells. Immunofluorescence assay showed that paclitaxel alone increased the expression of LC-3 in HO8910 cells, which was further enhanced by the combination with MAP2K6-FP. Downregulation of LC-3 expression using LC-3 small interfering RNA inhibited the cytotoxicity effect of MAP2K6-FP. Furthermore, either MAP2K6-FP alone or in combination with paclitaxel increased the ratio of expressions of Beclin-1/Bcl-2, another autophagy-related markers, compared with paclitaxel alone.
MAP2K6-FP enhanced the sensitiveness of paclitaxel for ovarian cancer via inducing autophagy.
紫杉醇被推荐作为治疗卵巢癌的一线化疗药物，但耐药性成为主要限制因素。卵巢癌中与紫杉醇耐药相关的关键分子或机制仍不清楚。最近的研究揭示了自噬与耐药性之间的关联。
我们之前合成了一种丝裂原活化蛋白激酶激酶重组融合蛋白，即MAP2K6-FP，它包含3个结构域：一个蛋白转导结构域TAT、一个人卵巢癌HO8910细胞特异性结合肽和一个潜在的抗肿瘤效应结构域MKK6(E)。在本研究中，我们研究了MAP2K6-FP对用紫杉醇处理的HO8910细胞的影响。
单独使用紫杉醇时的IC50（抑制50%细胞生长的浓度）为20 μM，单独使用MAP2K6-FP时为1.5 μg/mL，联合使用时MAP2K6-FP为0.3 μg/mL且紫杉醇为15 μM。此外，免疫组织化学分析表明，与正常卵巢组织相比，卵巢癌患者的肿瘤组织中自噬相关蛋白LC-3的表达更高。MAP2K6-FP（0、2.5、5、10、20和40 μg/mL）剂量依赖性地增加HO8910细胞中LC-3的表达。免疫荧光分析表明，单独使用紫杉醇可增加HO8910细胞中LC-3的表达，与MAP2K6-FP联合使用时进一步增强。使用LC-3小干扰RNA下调LC-3表达可抑制MAP2K6-FP的细胞毒性作用。此外，与单独使用紫杉醇相比，单独使用MAP2K6-FP或与紫杉醇联合使用均增加了另一种自噬相关标志物Beclin-1/Bcl-2的表达比值。
MAP2K6-FP通过诱导自噬增强了紫杉醇对卵巢癌的敏感性。
