Department of Immunology, College of Basic Medical Science, Central South University, Changsha, Hunan 410008, PR China.
Department of Gynecologic Tumor, Affiliated Cancer Hospital of Central South University, Changsha, Hunan 410013, PR China.
Exp Cell Res. 2019 May 15;378(2):139-148. doi: 10.1016/j.yexcr.2019.02.025. Epub 2019 Feb 28.
The objective of this study was to investigate the functional role of Rab39a in human cervical cancer (CC) and the underlying molecular mechanisms. We first measured Rab39a mRNA expression in CC tissues and paired non-tumor tissues by quantitative real-time PCR (QRT-PCR). Overall survival of CC patients with different mRNA levels of Rab39a in The Cancer Genome Atlas (TCGA) database was assessed by Kaplan-Meier survival curves analysis. Next methylation-specific PCR (MSP) was performed to determine the expression mechanism of Rab39a. Then cell proliferation, migration and invasion of Rab39a-transfected or mock-transfected cervical cancer cells were determined by CCK-8, flow cytometry, wound healing, transwell migration and invasion assays, respectively. Finally, the molecular mechanism by which Rab39a modulated CC cell epithelial-mesenchymal transition (EMT) was explored. It was found that Rab39a mRNA was significantly down-regulated in the high-risk patients compared to the low-risk patients (p = 0.0054). Six of seven cancer tissues with lymph node metastasis express low Rab39a mRNA compared to the surrounding non-tumor tissues. Cervical cancer patients with low level of Rab39a were showed a poorly clinical outcome (p = 0.004). Loss of Rab39a expression in cervical cancer tissues was associated with the aberrant DNA methylation in the promoter of Rab39a gene. Disrupted Rab39a expression in cervical cancer cells could be restored after treatment with the demethylated agent 5-Aza-2'-deoxycytidine. Furthermore, it was found that Rab39a hardly influenced cell growth but significantly suppressed cell migration, invasion and EMT process. Rab39a exerted its potential suppressor functions through inhibiting AKT phosphorylation. The inhibition effects of Rab39a could be blocked by AKT pathway inhibitor. Collectively, our data shows that Rab39a is a potential epigenetic silenced tumor suppressor inhibiting cancer invasion and migration through modulating the AKT signaling.
本研究旨在探讨 Rab39a 在人宫颈癌（CC）中的功能作用及其潜在的分子机制。我们首先通过实时定量 PCR（QRT-PCR）测量了 CC 组织和配对非肿瘤组织中 Rab39a mRNA 的表达。通过 Kaplan-Meier 生存曲线分析评估了 TCGA 数据库中 Rab39a 不同 mRNA 水平的 CC 患者的总体生存率。然后通过甲基化特异性 PCR（MSP）来确定 Rab39a 的表达机制。接着通过 CCK-8、流式细胞术、划痕愈合、Transwell 迁移和侵袭实验分别测定 Rab39a 转染或 mock 转染的宫颈癌细胞的增殖、迁移和侵袭。最后，探讨了 Rab39a 调节 CC 细胞上皮间质转化（EMT）的分子机制。结果发现，高危患者的 Rab39a mRNA 明显低于低危患者（p=0.0054）。与周围非肿瘤组织相比，有 6/7 例淋巴结转移的癌症组织表达低水平的 Rab39a mRNA。Rab39a 水平低的宫颈癌患者临床结局较差（p=0.004）。Rab39a 在宫颈癌组织中的表达缺失与 Rab39a 基因启动子的异常 DNA 甲基化有关。用去甲基化剂 5-Aza-2'-脱氧胞苷处理后，宫颈癌细胞中破坏的 Rab39a 表达可以得到恢复。此外，发现 Rab39a 几乎不影响细胞生长，但显著抑制细胞迁移、侵袭和 EMT 过程。Rab39a 通过抑制 AKT 磷酸化发挥其潜在的抑制功能。AKT 通路抑制剂可阻断 Rab39a 的抑制作用。综上所述，我们的数据表明，Rab39a 是一种潜在的表观遗传沉默的肿瘤抑制因子，通过调节 AKT 信号抑制癌症的侵袭和迁移。
