Department of Biochemistry and Molecular Biology, Chang Gung University College of Medicine, Taoyuan 333, Taiwan, Republic of China.
J Cell Biochem. 2013 Aug;114(8):1819-31. doi: 10.1002/jcb.24530.
Endometrial carcinoma (EC) is one of the main gynecologic malignancies affecting women, but effective treatments are currently lacking. In the present study, we investigated the effect of sorafenib, a general kinase inhibitor, on several EC cell lines (HEC1A, HEC1B, and RL95-2). Sorafenib induced cell death in EC cells with the following order of sensitivity: HEC1A > HEC1B > RL95-2. Sorafenib suppressed several anti-apoptotic proteins in HEC1A cells, including myeloid cell leukemia 1 (Mcl-1). Ectopic overexpression of Mcl-1 prevented the cell killing effect of sorafenib. Sorafenib suppressed Mcl-1 at the gene transactivation level by inactivating the ERK/Elk-1 pathway. Accordingly, the inhibitory effect of sorafenib on Mcl-1 expression decreased following knockdown of Elk-1 using short-hairpin RNA (shRNA). Elk-1 overexpression rescued both the inhibitory effect of sorafenib on Mcl-1 expression and the cell killing effect of sorafenib. Furthermore, sorafenib reduced the stability of the Mcl-1 protein by enhancing its ubiquitination and degradation by the proteasome via the AKT/GSK3β and the ERK pathways. Similar results were detected in other EC cell lines. These results indicate that sorafenib induces apoptosis in EC cells by down-regulating the anti-apoptotic protein Mcl-1 via transcriptional inhibition and protein degradation. Our results thus support the notion that sorafenib may be used in endometrial cancer therapy.
子宫内膜癌(EC)是影响女性的主要妇科恶性肿瘤之一,但目前缺乏有效的治疗方法。在本研究中,我们研究了索拉非尼(一种通用激酶抑制剂)对几种 EC 细胞系(HEC1A、HEC1B 和 RL95-2)的影响。索拉非尼诱导 EC 细胞死亡,其敏感性顺序为:HEC1A>HEC1B>RL95-2。索拉非尼抑制了 HEC1A 细胞中的几种抗凋亡蛋白,包括髓样细胞白血病 1(Mcl-1)。Mcl-1 的异位过表达可阻止索拉非尼的细胞杀伤作用。索拉非尼通过失活 ERK/Elk-1 通路抑制 Mcl-1 的基因转录激活,从而抑制 Mcl-1。因此,使用短发夹 RNA(shRNA)敲低 Elk-1 后,索拉非尼对 Mcl-1 表达的抑制作用降低。Elk-1 的过表达可挽救索拉非尼对 Mcl-1 表达的抑制作用和对细胞的杀伤作用。此外,索拉非尼通过 AKT/GSK3β 和 ERK 通路增强 Mcl-1 的泛素化和降解,从而降低 Mcl-1 蛋白的稳定性。在其他 EC 细胞系中也检测到了类似的结果。这些结果表明,索拉非尼通过抑制转录和蛋白降解下调抗凋亡蛋白 Mcl-1,诱导 EC 细胞凋亡。我们的结果支持索拉非尼可能用于子宫内膜癌治疗的观点。