By inhibiting Ras/Raf/ERK and MMP-9, knockdown of EpCAM inhibits breast cancer cell growth and metastasis

Epithelial cell adhesion molecule (EpCAM) is a type I transmembrane protein that is expressed in the majority of normal epithelial tissues and is overexpressed in most epithelial cancers including breast cancer, where it plays an important role in cancer progression. However, the mechanism by which EpCAM promotes the progression of breast cancer is not understood. In this study, we found that EpCAM expression was increased in tumor tissue from breast cancer patients compared to healthy patients. Overexpression of EpCAM in breast cancer cells enhanced tumor cell growth in vitro and increased invasiveness, whereas small interfering RNA-mediated silencing of EpCAM (si-EpCAM) had the opposite effect. EpCAM knockdown led to decreased phosphorylation of Raf and ERK, suppression of malignant behavior of breast cancer cells, and inhibition of the Ras/Raf/ERK signaling pathway. Furthermore, si-EpCAM-mediated invasion and metastasis of breast carcinoma cells required the downregulation of matrix metalloproteinase-9 (MMP-9) through inhibition of this signaling pathway. In conclusion, our data show that knockdown of EpCAM can inhibition breast cancer cell growth and metastasis via inhibition of the Ras/Raf/ERK signaling pathway and MMP-9.     

胰高糖素样肽-1受体激动剂对人甲状腺髓样癌细胞生长和能量代谢的影响

背景与目的：胰高糖素样肽-1(glucagon like peptide-1,GLP-1)受体激动剂是一种新型降糖药。在研发过程中,发现其可增加啮齿类动物患甲状腺C细胞肿瘤的风险。因此,该药物对人类甲状腺的影响引人关注。本研究旨在探讨GLP-1受体激动剂对人甲状腺髓样癌(medullary thyroid cancer,MTC)细胞增殖、降钙素的分泌和能量代谢的影响。方法：体外培养人MTC细胞系(TT)。分别以0、1、10和100 nmol/L艾塞那肽和利拉鲁肽处理细胞24、48和72 h后,采用细胞计数试剂盒(cell counting kit-8,CCK-8)检测GLP-1受体激动剂艾塞那肽和利拉鲁肽处理后细胞增殖情况;采用降钙素试剂盒测定细胞培养上清液中降钙素水平的变化;采用Seahorse能量代谢分析仪检测细胞糖酵解及线粒体呼吸的变化。结果：实验组细胞增殖率与对照组相比,差异无统计学意义(P>0.05),降钙素的量与对照组相比,差异无统计学意义(P>0.05),不同浓度艾塞那肽和利拉鲁肽处理细胞24 h后,与对照组相比,实验组艾塞那肽和利拉鲁肽对MTC细胞能量代谢并无明显影响(P>0.05),随着艾塞那肽和利拉鲁肽处理时间延长,TT细胞糖酵解和线粒体呼吸并无明显改变(P>0.05)。结论：GLP-1受体激动剂对人MTC发生、发展无明显促进作用,未来仍需大规模临床数据进一步证实GLP-1受体激动剂的安全性。     

Involvement of Ras/Raf-1/ERK actions in the magnolol-induced upregulation of p21 and cell-cycle arrest in colon cancer cells

Previously, we showed that magnolol induces cell-cycle arrest in cultured colon and liver cancer cells through an upregulation of the p21 protein. The aim of this study was to delineate the molecular mechanism underlying this magnolol-induced increase of p21 protein. Thus our RT-PCR analysis demonstrated that the mRNA levels of p21 were increased at 1 h after magnolol treatment and sustained for at least 24 h. The p21 promoter activity was also increased by magnolol treatment. Western blot analysis demonstrated that treatment of COLO-205 cells with magnolol increased the levels of phosphorylation of extracellular signal-regulated kinase (ERK). Pretreatment of the cells with PD98059 abolished the magnolol-induced upregulation of p21 protein, suggesting the involvement of an ERK pathway in the magnolol-induced upregulation of p21 in COLO-205 cells. Ras inhibitor peptide abolished the magnolol-induced increase of phosphorylated ERK protein levels, increase of p21 protein, and decrease of thymidine incorporation. Moreover, treatment of COLO-205 with magnolol increased the phosphorylated Raf-1 protein (the Ras target molecule). Pretreatment of the cells with Raf-1 inhibitor reversed the magnolol-induced decrease in thymidine incorporation. Treatment of the cells with CaM kinase inhibitor, but not protein kinase A (PKA) inhibitor or phosphatidylinosital 3-kinase (PI3K) inhibitor, abolished the magnolol-induced activation of ERK and decrease of thymidine incorporation. Taken together, our results suggest that magnolol activates ERK phosphorylation through a Ras/Raf-1-mediated pathway. Subsequently, p21 expression is increased, and finally thymidine incorporation is decreased.     

Recombinant leukemia inhibitory factor suppresses human medullary thyroid carcinoma cell line xenografts in mice

Medullary thyroid carcinoma (MTC) is a neoplasm of the endocrine system, which originates from parafollicular C-cells of the thyroid gland. For MTC therapy, the Food and Drug Administration recently approved vandetanib and cabozantinib, multi-kinase inhibitors targeting RET and other tyrosine kinase receptors of vascular endothelial growth factor, epidermal growth factor, or hepatocyte growth factor. Nevertheless, not all patients with the progressive MTC respond to these drugs, requiring the development of additional therapeutic modalities that have distinct activity. Previously, we reported that expression of activated Ras or Raf in the human MTC cell lines, TT and MZ-CRC-1, can induce growth arrest and RET downregulation via a leukemia inhibitory factor (LIF)-mediated autocrine/paracrine loop. In this study, we aimed to evaluate bacterially-produced recombinant human LIF for its efficacy to suppress human MTC xenografts in mice. Here, we report that, consistent with its effects in vitro, locally or systemically administered recombinant LIF effectively suppressed growth of TT and MZ-CRC-1 xenografts in mice. Further, as predicted from its effects in TT and MZ-CRC-1 cell cultures in vitro, recombinant LIF activated the JAK/STAT pathway and downregulated RET and E2F1 expression in tumors in mice. These results suggest that LIF is a potent cytostatic agent for MTC cells, which regulates unique mechanisms that are not targeted by currently available therapeutic agents.     

Efficacy of epidermal growth factor receptor-targeted molecular therapy in anaplastic thyroid cancer cell lines

Anaplastic thyroid cancer is one of the most aggressive human malignancies and the outcomes of conventional therapy have been far from satisfactory. Recently, epidermal growth factor receptor (EGFR)-targeted therapy has been introduced as an alternative therapeutic strategy for highly malignant cancers. This study was undertaken to investigate the expression of EGFR in anaplastic thyroid cancer cell lines, and to explore the potential of therapies targeting EGFR as a new therapeutic approach. EGFR was universally expressed in anaplastic cancer cell lines at a variety of levels. Specific EGFR stimulation with epidermal growth factor showed significant phosphorylation of ERK1/2 and Akt, and resulted in marked growth stimulation in an anaplastic thyroid cancer cell line, which highly expressed EGFR. This EGFR-transmitted proliferation effect of the cancer cell line was completely inhibited by gefitinib, an EGFR tyrosine kinase inhibitor. Moreover, growth of xenografts inoculated in mice was inhibited in a dose-dependent manner with 25-50 mg kg(-1) of gefitinib administrated orally. Inhibition of EGFR-transmitted growth stimulation by gefitinib was clearly observed in anaplastic thyroid cancer cell lines. Our results suggested that EGFR-targeted therapy, such as gefitinib, might be worth further investigation for the treatment of anaplastic thyroid cancer.     

Epidermal growth factor receptor activation confers resistance to lenvatinib in thyroid cancer cells

Thyroid cancer is the most common endocrine malignancy. A multitargeted tyrosine kinase inhibitor, lenvatinib, has been used for the treatment of advanced thyroid cancer. To elucidate the mechanism of resistance to lenvatinib in thyroid cancer cells, we established lenvatinib‐resistant sublines and analyzed the molecular mechanisms of resistance. Two thyroid cancer cell lines (TPC‐1 and FRO) were used, and resistant sublines for lenvatinib (TPC‐1/LR, FRO/LR) were established. In TPC‐1/LR, the phosphorylation of epidermal growth factor receptor (EGFR), extracellular signal‐regulated kinase (ERK), and Akt was enhanced whereas in FRO/LR, the phosphorylation of EGFR and downstream signal transduction molecules was not enhanced. The addition of epidermal growth factor decreased sensitivity to lenvatinib in TPC‐1 and FRO. The combination of EGFR inhibitors lapatinib and lenvatinib significantly inhibited the growth of TPC‐1/LR in both in vitro and mouse xenograft models. Short‐term exposure to lenvatinib enhanced the phosphorylation of EGFR in six thyroid cancer cell lines regardless of their histological origin or driver gene mutations; however, phosphorylation of ERK was enhanced in all cells except TPC‐1. A synergistic growth‐inhibitory effect was observed in three thyroid cancer cell lines, including intrinsically lenvatinib‐resistant cells. The results indicate that signal transduction via the EGFR pathway may be involved in the development of lenvatinib resistance in thyroid cancer cells. The inhibition of the EGFR pathway simultaneously by an EGFR inhibitor may have therapeutic potential for overcoming lenvatinib resistance in thyroid cancer.     

Tumor-derived macrophage migration inhibitory factor modulates the biology of head and neck cancer cells via neutrophil activation

Macrophage migration inhibitory factor (MIF) is an inflammatory cytokine that has been reported to enhance the aggressiveness and metastatic potential of tumor cells. However, the mechanisms through which MIF influences tumor development and progression are not understood. The objectives of our study were to assess the effects of tumor-derived MIF on neutrophils in head and neck cancer (HNC) and to identify possible feedback effects on tumor cells. To this end, we used an in vitro system to model the interaction between human HNC cells and neutrophils. In addition, we analyzed expression of MIF in tissues from HNC patients in relation to neutrophilic infiltration and clinical parameters. Our results show that human HNC is infiltrated by neutrophils proportional to the levels of tumoral MIF. Strong MIF expression by the tumor is associated with higher lymph node metastasis and reduced survival in HNC patients. In vitro, MIF modulated functions of human neutrophils by inducing chemokine CXC motif receptor 2(CXCR2)-dependent chemotaxis, enhancing neutrophil survival and promoting release of chemokine C-C Motif Ligand 4 (CCL4) and matrix metalloprotease 9(MMP9). Further, neutrophils activated with tumor-derived MIF enhanced migratory properties of HNC cells. In conclusion, our data indicate that the effects of tumor-derived MIF on neutrophils represent an additional mechanism by which MIF might contribute to tumor progression.     

巨噬细胞移动抑制因子在结直肠癌中的研究进展

巨噬细胞移动抑制因子(macrophage migration inhibitory factor,MIF)作为与免疫细胞活化有关的可溶性细胞因子,与细胞的多种生物学行为关系密切.其在肿瘤的发生、发展过程发挥重要作用.近期,MIF被证明可通过介导下游多条信号通路广泛参与结直肠癌(colorectal cancer,CR...     

Transactivation of epidermal growth factor receptor through platelet-activating factor/receptor in ovarian cancer cells

Background

We previously identified platelet-activating factor receptor (PAFR) as being overexpressed in ovarian cancer and found that its ligand PAF evoked EGFR phosphorylation using the phospho-antibody microarray. Epidermal growth factor receptor (EGFR) are also overexpressed in ovarian cancer and contribute to the growth of ovarian cancer cells. Here, we investigated the mechanisms of crosstalk between PAFR and EGFR signaling in ovarian cancer cells to further determine whether the interaction between PAFR and EGFR synergistic contribute to the progression of ovarian cancer.

Methods

Expression and localization of PAFR in several ovarian cancer cell lines were assessed by Western blot, realtime-PCR and immunofluorescence. The ovarian cancer cells were stimulated with PAF or PAF and in some experiments also pharmacological inhibitors. Phosphorylation of proteins in signaling pathways were measured by Western blot. HB-EGF concentrations of the supernatant from stimulated ovarian cancer cells were measured by enzyme-linked immunosorbent assay.

Results

Our data show that PAF increases EGFR phosphorylation through PAFR in a time- and dose- dependent manner in SKOV-3 ovarian cancer cells. This transactivation is dependent on phospholipase C-β and intracellular calcium signaling. This pathway is also Src tyrosine kinase- and metalloproteinase- dependent. PAF triggers EGFR activation through the increased heparin-binding EGF-like growth factor (HB-EGF) release in metalloprotease-dependent manner. Several studies involving EGFR transactivation through G-protein coupled receptor (GPCR) have demonstrated EGFR-dependent increase in ERK1/2 phosphorylation. Yet in SKOV-3 cells, PAF treatment also increases ERK1/2 phosphorylation in a EGFR-independent manner.

Conclusions

The results suggest that in SKOV-3 ovarian cancer cells, PAF transactivates EGFR and downstream ERK pathways, thus diversifying the GPCR-mediated signal. The crosstalk between PAFR and EGFR suggests a potentially important signaling linkage between inflammatory and growth factor signaling in ovarian cancer cells.     

过表达巨噬细胞移动抑制因子对子宫颈癌SiHa细胞上皮间质转化的影响

目的 探讨过表达巨噬细胞移动抑制因子（MIF）对子宫颈癌SiHa细胞发生上皮间质转化 （EMT）的影响.方法 应用基因转染方法将重组质粒pEGFP-N1-MIF转入SiHa细胞,构建过表达MIF的SiHa细胞;用实时荧光聚合酶链反应（RT-PCR）及免疫细胞化学方法分别检测各组细胞中E-cadherin、vimentin mRNA及蛋白的表达水平.结果 RT-PCR检测结果显示,转染pEGFP-N1-MIF的细胞中MIF mRNA相对表达量升高（F=2950.278,P＜ 0.01）;转染pEGFP-NI-MIF的细胞中vimentin的mRNA高于各对照组,而E-cadherin的mRNA低于各对照组（F值分别为2 135.048,1 893.563,均P＜0.01）;转染pEGFP-N 1-MIF的细胞中vimentin的蛋白表达水平高于各对照组,而E-cadherin的蛋白表达水平低于各对照组（F值分别为2 348.021,1 789.421,均P＜ 0.01）.结论 过表达MIF促进SiHa细胞中vimentin表达,抑制E-cadherin表达,说明过表达MIF促进子宫颈癌SiHa细胞发生上皮间质转化.     

毛蕊异黄酮通过Nrf2/HO-1信号途径诱导人甲状腺癌FTC-133细胞发生铁死亡

目的:观察毛蕊异黄酮（CA）是否可诱导人甲状腺癌细胞系FTC-133细胞铁死亡并探讨其可能机制。方法: 采用RPMI 1640培养液培养FTC-133细胞,分为对照和CA、铁死亡抑制剂ferrostatin-1、血红素氧合酶-1（HO-1）激动剂CoPP、CA+ferrostatin-1和CA+CoPP组。CCK-8法检测细胞增殖。相应试剂盒检测细胞活性氧（ROS）、还原型谷胱甘肽（GSH）、丙二醛（MDA）、总铁和二价铁离子水平。Western Blot检测细胞中谷胱甘肽过氧化物酶4（GPX4）、铁蛋白重链1（FTH1）、核因子E2相关因子2（Nrf2）和HO-1蛋白表达。结果:与对照组比较,CA（50、100和150 μmol/L）处理在24 h、48 h和72 h三个时间点均降低细胞存活率,并呈现剂量依赖性（均P＜0.05）。与对照组比较,CA（50、100和150 μmol/L）处理48 h降低细胞中GSH的浓度（均P＜0.05）,增加了FTC-133细胞中ROS、MDA、总铁和二价铁离子浓度（均P＜0.05）。与对照组比较,CA（50、100和150 μmol/L）处理48 h显著降低细胞中GPX4（P＜0.05）和FTH1（P＜0.05）蛋白表达水平（均P＜0.05）。Ferrostatin-1部分逆转了CA诱导FTC-133细胞铁死亡的作用（均P＜0.05）。与对照组比较,CA（50、100和150 μmol/L）处理均降低Nrf2在细胞核中的表达及Nrf2在细胞核中表达与Nrf2总蛋白表达的比值（均P＜0.05）,而没有影响Nrf2总蛋白表达（均P＞0.05）。与对照组比较,CA（50、100和150 μmol/L）处理均降低细胞中HO-1的蛋白表达（均P＜0.05）。CoPP部分逆转了CA诱导FTC-133细胞铁死亡的作用（均P＜0.05）。结论:CA诱导了人甲状腺癌细胞系FTC-133细胞发生铁死亡,而其机制可能是通过Nrf2/HO-1信号通路。     

Role of transforming growth factor beta in the growth inhibition of human breast cancer cells by basic fibroblast growth factor

Recent studies from our laboratory have revealed that basic fibroblast growth factor (bFGF) selectively inhibits the proliferation of human MCF-7 breast cancer cells. It has also been shown to enhance cis-platinum-induced apoptosis, decrease levels of the anti-apoptotic gene product bcl-2, and increase levels of the cyclin-dependent protein kinase inhibitor p21/WAF1/Cip1. Transforming growth factor beta-1 (TGF₁), a cell growth regulator has been found to have an inhibitory effect on breast cancer cells. The aim of the present study was to evaluate the possible role of TGF₁ in the antiproliferative effects of bFGF in MCF-7 breast cancer cells. We found that exogenous, as well as endogenous (overexpressed) bFGF increased TGF₁ mRNA expression in the cells and enhanced the secretion of TGF₁ into culture medium. However, exogenous addition of TGF₁ neither led to a decrease in bcl-2 nor induced an increase in the levels of p21/WAF1/Cip1 and neutralizing antibodies to TGF₁, did not reverse bFGF-induced G₁ arrest nor the increase in p21/WAF1/Cip1 level. In contrast, antisense oligonucleotides to TGF₁ abrogated the antiproliferative effects and inhibited the induction of p21/WAF1/Cip1 by bFGF in MCF-7 cells. These data suggest that the anti-proliferative effects of bFGF in human MCF-7 breast cancer cells are mediated by endogenous TGF₁, while exogenous TGF₁ does not mimic all the effects of bFGF on these breast cancer cells. These findings provide an important basis for further investigations into the autocrine and paracrine processes that control the growth of breast cancer cells.     

Co-expression of hepatocyte growth factor and c-Met predicts peritoneal dissemination established by autocrine hepatocyte growth factor/c-Met signaling in gastric cancer

Epithelial-mesenchymal transition (EMT) promotes and facilitates migration and invasion of epithelial tumor cells. EMT is induced by factors such as hepatocyte growth factor (HGF). This study aimed to establish whether the HGF/c-Met pathway is associated with gastric cancer metastasis; especially peritoneal dissemination. HGF and c-Met expression and EMT-related molecules were evaluated using real-time PCR and immunohistochemistry. The role of the HGF/c-Met pathway in EMT and anoikis was determined, and kinase inhibitor SU11274 was tested for its ability to block HGF-induced biological effects. In HGF(-) /c-Met(+) gastric cancer cells, recombinant HGF promoted an EMT phenotype that was characterized by morphology, impaired E-cadherin and induction of vimentin. HGF promoted cell growth, invasiveness and migration and inhibition of anoikis. SU11274 blocked HGF-induced EMT and biological effects in vitro. In HGF(+) /c-Met(+) gastric cancer cells, HGF did not affect the biological outcome of EMT and anoikis, but SU11274 exerted the same inhibitory effects as in HGF(-) /c-Met(+) cells. In vivo, HGF(+) /c-Met(+) gastric cancer cells only established peritoneal dissemination and SU11274 inhibited tumor growth. Clinically, HGF expression was significantly correlated with c-Met expression in gastric cancer. Increased HGF and c-Met had a significant association with poor prognosis and predicted peritoneal dissemination. We demonstrated that the HGF/c-Met pathway induces EMT and inhibition of anoikis in gastric cancer cells. Co-expression of HGF and c-Met has the potential to promote peritoneal dissemination in gastric cancer. Blockade of the autocrine HGF/c-Met pathway could be clinically useful for the treatment of peritoneal dissemination in gastric cancer.     

Slit/Robo信号通路在胰腺癌细胞中的表达及其对胰腺癌细胞生长的影响

目的 探讨Slit/Robo信号通路在胰腺癌细胞中的表达情况,及其对胰腺癌细胞增殖的影响.方法 分别采用RT-PCR、免疫细胞化学、免疫荧光方法 检测胰腺癌细胞株BxPC-3、Panc-1中Slit和Robo的表达;通过Slit/Robo信号通路阻断剂RoboN阻断该通路,采用MTT法观察其对细胞生长的影响.结果 胰腺癌细胞株Bx-PC-3、Panc-1中存在着Slit2、Robo1基因和蛋白表达;在RoboN的作用下,胰腺癌细胞体外生长受到抑制,增殖能力下降.结论 胰腺癌细胞中可能存在着Slit2/Robo1信号通路,它能够负性调节胰腺癌细胞的生长,提示Slit/Robo信号通路可能参与了胰腺癌的发生发展的过程.     

D‐dopachrome tautomerase is over‐expressed in pancreatic ductal adenocarcinoma and acts cooperatively with macrophage migration inhibitory factor to promote cancer growth

Previous studies have established the important role of MIF in the development of pancreatic ductal adenocarcinoma (PDAC) for both therapeutic and diagnostic perspectives, but little is known about the expression and function of D‐dopachrome tautomerase (DDT), a functional homolog of MIF, in PDAC. In the present study, we demonstrated that DDT was over‐expressed in PDAC tissues in a pattern correlated with MIF. In the pancreatic cancer cell lines, PANC‐1, BXPC‐3 and ASPC‐1, both DDT and MIF were expressed and co‐localized with each other in the endosomal compartments and plasma membrane. Knockdown of DDT and MIF in PANC‐1 cells cooperatively inhibited ERK1/2 and AKT phosphorylation, increased p53 expression, and reduced cell proliferation, invasion and tumor formation. These effects were rescued by the re‐expression of MIF or DDT, but not by the forced expression of the tautomerase‐deficient mutants of DDT and MIF, P1G‐DDT and P1G‐MIF. Finally, we observed that 4‐iodo‐6‐phenylpyrimidine (4‐IPP), a covalent tautomerase inhibitor of both DDT and MIF, attenuated PANC‐1 cell proliferation and colony formation in vitro and tumor growth in vivo. Thus, targeting the tautomerase sites of both MIF and DDT may offer more efficient therapeutic benefits to PDAC patients.