Chemoresistance to gemcitabine in hepatoma cells induces epithelial-mesenchymal transition and involves activation of PDGF-D pathway

Hepatocellular carcinoma (HCC) is one of the common malignances in the world and has high mortality in part due to development of acquired drug resistance. Therefore, it is urgent to investigate the molecular mechanism of drug resistance in HCC. To explore the underlying mechanism of drug resistance in HCC, we developed gemcitabine-resistant (GR) HCC cells. We used multiple methods to achieve our goal including RT-PCR, Western blotting analysis, transfection, Wound-healing assay, migration and invasion assay. We observed that gemcitabine-resistant cells acquired epithelial-mesenchymal transition (EMT) phenotype. Moreover, we found that PDGF-D is highly expressed in GR cells. Furthermore, down-regulation of PDGF-D in GR cells led to partial reversal of the EMT phenotype. Our findings demonstrated that targeting PDGF-D could be a novel strategy to overcome gemcitabine resistance in HCC.     

miR-21促进肺癌EGFR-TKI耐药细胞株上皮—间质细胞转化的研究

[目的]研究miR-21是否可以调控上皮—间质转化（EMT）而参与肺癌获得性耐药。[方法]使用HCC827细胞（EGFR基因19外显子缺少的肺腺癌细胞株）,在此细胞的基础上培养吉非替尼耐药细胞株HCC827/GR。检测耐药细胞株中miR-21的表达,同时观察耐药细胞的形态变化,及在耐药细胞株中抑制miR-21表达后检测耐药细胞株的侵袭能力及EMT相关蛋白E-cadherin和Vimentin的表达。[结果]与敏感细胞株HCC827相比,HCC827/GR细胞株对吉非替尼的耐药倍数约为100倍;同时在耐药细胞株中我们发现miR-21较敏感株表达增高约5.3倍,同时细胞形态发生了明显变化。通过检测EMT相关蛋白,我们发现耐药细胞株中间质相关蛋白Vimentin明显高表达,而上皮相关蛋白E-cadherin明显低表达,当miR-21被抑制后,耐药细胞株侵袭能力下降,同时Vimentin表达量下降,而E-cadherin表达量增高。[结论]miR-21可能通过促进EMT参与肺癌EGFR-TKI的获得性耐药。     

miR-186 Suppresses the Progression of Cholangiocarcinoma Cells Through Inhibition of Twist1

Deregulation of miR-186 and Twist1 has been identified to be involved in the progression of multiple cancers. However, the detailed molecular mechanisms underlying miR-186-involved cholangiocarcinoma (CCA) are still unknown. In this study, we found that miR-186 was downregulated in CCA tissues and cell lines, and negatively correlated with the expression of Twist1 protein. In vitro assays demonstrated that miR-186 mimics repressed cell proliferation, in vivo tumor formation, and caused cell cycle arrest. miR-186 mimics also inhibited the migration and invasion of CCLP1 and SG-231 cells. Mechanistically, the 3′-untranslated region (3′-UTR) of Twist1 mRNA is a direct target of miR-186. Further, miR-186 inhibited the expressions of Twist1, N-cadherin, vimentin, and matrix metallopeptidase 9 (MMP9) proteins, whereas it increased the expression of E-cadherin in CCLP1 and SG-231 cells. Silencing of Twist1 expression enhanced the inhibitory effects of miR- 186 on the proliferation, migration, and invasion of CCLP1 and SG-231 cells. In conclusion, miR-186 inhibited cell proliferation, migration, invasion, and epithelial–mesenchymal transition (EMT) through targeting Twist1 in human CCA. Thus, miR-186/Twist1 axis may benefit the development of therapies for CCA.     

MicroRNA 495 Inhibits Proliferation and Metastasis and Promotes Apoptosis by Targeting Twist1 in Gastric Cancer Cells

Recently, microRNAs (miRNAs) have been reported to participate in multiple biological processes. However, the effects of miR-495 on gastric cancer (GC) remain unclear. The purpose of this study was to explore the functions of miR-495 in GC cell proliferation, metastasis, and apoptosis. SGC-7901 and BGC-823 cell lines were transfected with miR-495 mimic, miR-495 inhibitor, and negative controls (mimic control and inhibitor control). The expressions of miR-495, cell viability, migration, apoptosis, and apoptosis-related factors were examined by qRT-PCR, trypan blue staining, Transwell, flow cytometry, and Western blot, respectively. Simultaneously, key factor expression levels of EMT were detected by qRT-PCR and Western blot. The direct target of miR-495 was confirmed by dual-luciferase assay. Additionally, sh-Twist1, pc-Twist1, and corresponding controls were transfected into SGC-7901 and BGC-823 cells, and the protein levels of EMTassociated factors were detected by Western blot. miR-495 was downregulated in GC cells. miR-495 expression level was effectively overexpressed or suppressed in SGC-7901 and BGC-823 cells. Overexpression of miR-495 significantly decreased cell viability and migration, increased apoptosis, and inhibited the EMT process. Suppression of miR-495 showed contrary results. Twist1 was clarified as a target gene of miR-495, and Twist1 silencing obviously reduced the promoting effect of miR-495 suppression on these biological processes. Twist1 silencing significantly blocked the EMT process in both SGC-7901 and BGC-823 cells. miR-495 inhibited proliferation and metastasis and promoted apoptosis by targeting Twist1 in GC cells. These data indicated that miR-495 might be a novel antitumor factor of GC and provide a new method for the treatment of GC.     

MiR-203 downregulation is responsible for chemoresistance in human glioblastoma by promoting epithelial-mesenchymal transition via SNAI2

Epithelial-mesenchymal transition (EMT) has been recognized as a key element of cell migration, invasion, and drug resistance in several types of cancer. In this study, our aim was to clarify microRNAs (miRNAs)-related mechanisms underlying EMT followed by acquired resistance to chemotherapy in glioblastoma (GBM). We used multiple methods to achieve our goal including microarray analysis, qRT-PCR, western blotting analysis, loss/gain-of-function analysis, luciferase assays, drug sensitivity assays, wound-healing assay and invasion assay. We found that miR-203 expression was significantly lower in imatinib-resistant GBM cells (U251AR, U87AR) that underwent EMT than in their parental cells (U251, U87). Ectopic expression of miR-203 with miRNA mimics effectively reversed EMT in U251AR and U87AR cells, and sensitized them to chemotherapy, whereas inhibition of miR-203 in the sensitive lines with antisense oligonucleotides induced EMT and conferred chemoresistance. SNAI2 was identified as a direct target gene of miR-203. The knockdown of SNAI2 by short hairpin RNA (shRNA) inhibited EMT and drug resistance. In GBM patients, miR-203 expression was inversely related to SNAI2 expression, and those tumors with low expression of miR-203 experienced poorer clinical outcomes. Our findings indicate that re-expression of miR-203 or targeting SNAI2 might serve as potential therapeutic approaches to overcome chemotherapy resistance in GBM.     

HIFs enhance the migratory and neoplastic capacities of hepatocellular carcinoma cells by promoting EMT

Hepatocellular carcinoma (HCC) is one of the most fatal cancers. Although the involvement of the epithelial-to-mesenchymal transition (EMT) in HCC progression is established, the mechanisms modulating this phenomenon remain unclear. Here, we demonstrate that hypoxia-inducible factors (HIFs), HIF-1α and HIF-2α, modulate the EMT through Twist1, a regulator of the EMT. The levels of HIF-1α and HIF-2α in HCC tissues were higher than those in matched, non-tumor surrounding tissues. In HCC samples, the levels of HIF-1α and HIF-2α negatively correlated with the levels of E-cadherin but positively correlated with the levels of vimentin. In highly metastatic MHCC97H cells, the levels of HIF-1α, HIF-2α, and Twist1 were higher than those in weakly metastatic HepG2 cells. In HepG2 cells, over-expression of HIFs enhanced levels of Twist1 and the EMT, which elevated the migratory and neoplastic capacities of cells. For MHCC97H cells, inhibition of HIFs reduced Twist1 levels and the EMT, which reduced their migratory and neoplastic capacity. Thus, the promotion of EMT by HIFs via Twist1 enhanced the migration and neoplastic capacities of HCC cells.     

Twist overexpression correlates with hepatocellular carcinoma metastasis through induction of epithelial-mesenchymal transition.

PURPOSE: Hepatocellular carcinoma (HCC) is a rapidly growing tumor associated with a high propensity for vascular invasion and metastasis. Epithelial-mesenchymal transition (EMT) is a key event in the tumor invasion process. Recently, Twist has been identified to play an important role in EMT-mediated metastasis through the regulation of E-cadherin expression. However, the actual role of Twist in tumor invasiveness remains unclear. The purpose of this study is to investigate the expression and possible role of Twist in HCC. EXPERIMENTAL DESIGN: We evaluated Twist and E-cadherin expression in HCC tissue microarray of paired primary and metastatic HCC by immunohistochemical staining. The role of Twist in EMT-mediated invasiveness was also evaluated in vitro in HCC cell lines. RESULTS: We first showed that overexpression of Twist was correlated with HCC metastasis (P=0.001) and its expression was negatively correlated with E-cadherin expression (P=0.001, r=-0.443) by tissue microarray. A significant increase of Twist at the mRNA level was also found in metastatic HCC cell lines MHCC-97H, MHCC-97L, and H2M when compared with nonmetastatic Huh-7, H2P, and PLC cell lines. The MHCC-97H cell line, which has a higher metastatic ability, was found to have a higher level of Twist than MHCC-97L. Accompanied with increased Twist expression in the metastatic HCC cell lines when compared with the nonmetastatic primary ones, we found decreased E-cadherin mRNA expression in the metastatic HCC cell lines. By ectopic transfection of Twist into PLC cells, Twist was able to suppress E-cadherin expression and induce EMT changes, which was correlated with increased HCC cell invasiveness. CONCLUSION: This study shows that Twist overexpression was correlated with HCC metastasis through induction of EMT changes and HCC cell invasiveness.     

MicroRNA-214 regulates the acquired resistance to gefitinib via the PTEN/AKT pathway in EGFR-mutant cell lines

Patients with non-small cell lung cancer (NSCLC) who have activating epidermal growth factor receptor (EGFR) mutations derive clinical benefit from treatment with EGFR-tyrosine kinase inhibitors ((EGFR-TKIs)- namely gefitinib and erlotinib. However, these patients eventually develop resistance to EGFR-TKIs. Despite the fact that this acquired resistance may be the result of a secondary mutation in the EGFR gene, such as T790M or amplification of the MET proto-oncogene, there are other mechanisms which need to be explored. MicroRNAs (miRs) are a class of small non-coding RNAs that play pivotal roles in tumorigenesis, tumor progression and chemo-resistance. In this study, we firstly successfully established a gefitinib resistant cell line-HCC827/GR, by exposing normal HCC827 cells (an NSCLC cell line with a 746E-750A in-frame deletion of EGFR gene) to increasing concentrations of gefitinib. Then, we found that miR-214 was significantly up-regulated in HCC827/ GR. We also showed that miR-214 and PTEN were inversely expressed in HCC827/GR. Knockdown of miR-214 altered the expression of PTEN and p-AKT and re-sensitized HCC827/GR to gefitinib. Taken together, miR-214 may regulate the acquired resistance to gefitinib in HCC827 via PTEN/AKT signaling pathway. Suppression of miR-214 may thus reverse the acquired resistance to EGFR-TKIs therapy.     

miR-509-3p在肝癌组织中的表达及对肝癌细胞迁移侵袭的影响

背景与目的：肝细胞癌（hepatocellular carcinoma，HCC）是世界范围内致死率第三高的恶性肿瘤，microRNA（miRNA）被认为在HCC的发病机制中起重要作用。本研究旨在探讨在原发性肝癌中miR-509-3p的表达水平、细胞功能及调控的相关基因。方法：通过实时荧光定量聚合酶链反应（real-time fluorescent quantitative polymerase chain reaction，RTFQ-PCR）技术检测miR-509-3p在46例肝癌患者组织样本、人肝癌细胞系及永生化人正常肝细胞系中的表达水平，采用transwell实验检测miR-509-3p对肝癌细胞转移的影响。采用蛋白质印迹法（Western blot）检测miR-509-3p与上皮-间质转化（epithelial-mesenchymal transition，EMT）相关基质金属蛋白酶（matrix metalloproteinase，MMP）之间的关系。结果：RTFQ-PCR技术检测结果显示，miR-509-3p在46例肝癌患者的肝癌组织样本以及MHCC97H、HCCLM3和SMMC-7721肝癌细胞系中异常高表达。体外功能实验证实抑制miR-509-3p表达能降低MHCC97H和HCCLM3肝癌细胞的迁移能力。Western blot检测结果显示，在MHCC97H和HCCLM3肝癌细胞中抑制miR-509-3p的表达可以降低MMP-9和MMP-2蛋白的表达。结论：本研究表明miR-509-3p通过正向调控MMP-9和MMP-2蛋白的表达而促进肝癌细胞的迁移和侵袭。     

Tunicamycin inhibits cell proliferation and migration in hepatocellular carcinoma through suppression of CD44s and the ERK1/2 pathway

Tunicamycin (TM) is an N‐linked glycosylation (NLG) inhibitor with strong antitumor activity, the exact underlying molecular mechanism of which remains to be elucidated. In our previous studies, we found that TM reversed drug resistance and improved the efficacy of combination treatments for hepatocellular carcinomas (HCC). Here, we investigated the effects of TM on HCC cell proliferation and migration as well as the mechanism of those effects. Our results showed that TM inhibited cell proliferation and migration as well as induced apoptosis of hepatocellular carcinoma cells. TM inhibited proliferation of HCC cells by inducing cell apoptosis and cell cycle arrest at the G2/M phase. Meanwhile, TM inhibited migration of HCC cells by suppressing CD44s‐mediated epithelial‐mesenchymal transition (EMT). TM inhibited migration and invasion of HCC cells by decreasing CD44 expression and altering its glycosylation. In addition, CD44s is involved in promoting EMT and is associated with a poor prognosis in HCC patients. Overexpression of CD44s promoted tumor migration and activated phosphorylation of ERK1/2 in HCC cells, whereas TM inhibited CD44s overexpression‐associated cell migration. The ability of TM to inhibit cell migration and invasion was enhanced or reversed in CD44s knockdown cells and cells overexpressing CD44s, respectively. The MEK/ERK inhibitor U0126 and TM inhibited hyaluronic acid‐induced cell migration in HCC cells. Furthermore, TM inhibited exogenous transforming growth factor beta (TGF‐β)‐mediated EMT by an ERK1/2‐dependent mechanism and restored the TGF‐β‐mediated loss of E‐cadherin. In summary, our study provides evidence that TM inhibits proliferation and migration of HCC cells through inhibition of CD44s and the ERK1/2 signaling pathway.     

MicroRNA-451: epithelial-mesenchymal transition inhibitor and prognostic biomarker of hepatocelluar carcinoma

Increasing evidence indicates that dysregulation of microRNAs (miRNAs) plays critical roles in malignant transformation and tumor progression. Previously, we have shown that microRNA-451 (miR-451) inhibits growth, increases chemo- or radiosensitivity and reverses epithelial to mesenchymal transition (EMT) in lung cancer. However, the roles of miR-451 in hepatocelluar carcinoma (HCC) progression and metastasis are still largely unknown. Reduced miR-451 in HCC tissues was observed to be significantly correlated with advanced clinical stage, metastasis and worse disease-free or overall survival. Through gain- and loss-of function experiments, we demonstrated that miR-451 inhibited cell growth, induced G0/G1 arrest and promoted apoptosis in HCC cells. Importantly, miR-451 could inhibit the migration and invasion in vitro, as well as in vivo metastasis of HCC cells through regulating EMT process. Moreover, the oncogene c-Myc was identified as a direct and functional target of miR-451 in HCC cells. Knockdown of c-Myc phenocopied the effects of miR-451 on EMT and metastasis of HCC cells, whereas overexpression of c-Myc partially attenuated the functions of miR-451 restoration. Furthermore, miR-451 downregulation-induced c-Myc overexpression leads to the activation of Erk1/2 signaling, which induces acquisition of EMT phenotype through regulation of GSK-3β/snail/E-cadherin and the increased expression of MMPs family members in HCC cells. Collectively, these data demonstrated that miR-451 is a novel prognostic biomarker for HCC patients and that function as a potential metastasis inhibitor in HCC cells through activation of the Erk1/2 signaling, at least partially by targeting c-Myc. Thus, targeting miR-451/c-Myc/Erk1/2 axis may be a potential strategy for the treatment of metastatic HCC.     

卵巢癌组织中PD-L1表达与EMT及其转录因子的相关性

目的:分析卵巢癌组织中PD-L1表达、上皮间质转化（epithelial mesenchymal transition,EMT）与临床病理生物学行为间的关系,探讨卵巢癌组织中PD-L1表达与EMT及其转录因子的相关性。方法:采用免疫组织化学染色检测106例原发性卵巢上皮性癌组织中PD-L1和EMT相关蛋白（E-cadherin、Vimentin）及转录因子Twist、Snail的表达情况,并进行相关性分析。结果:106例卵巢癌组织中PD-L1蛋白的阳性表达率为65.1%（69/106）,EMT发生率为35.8%（38/106）。在有淋巴结转移组、有脉管侵犯组及有恶性腹水组中PD-L1表达及EMT发生率均高于无淋巴结转移组、无脉管侵犯组及无恶性腹水组,差异具有统计学意义（P＜0.05）。69例PD-L1阳性表达的卵巢癌组织中有34例存在EMT阳性表型,PD-L1阳性表达与EMT阳性表型之间呈明显的正相关（r=0.300,P=0.002）。在69例PD-L1阳性表达的卵巢癌组织中发现49例转录因子Twist阳性表达,44例Snail阳性表达,PD-L1的表达与转录因子Twist和Snail的表达呈正相关（r值分别为0.272及0.223,P＜0.05）。结论:在人卵巢癌标本中,PD-L1表达与EMT相关蛋白的表达有密切关系,PD-L1过度表达可能上调转录因子Twist和Snail的表达,进而诱导卵巢癌EMT的发生,促进肿瘤的进展和转移。