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Accumulating clinical and experimental evidence has suggested that Helicobacter pylori (H. pylori) infection-associated gastric cancer (GC) is associated with high rates of mortality and serious health effects. The majority of patients succumb to H. pylori infection-associated GC due to metastasis. Mesenchymal stem cells (MSCs), which have multipotent differentiation potential, may be recruited into the tumor-associated stroma. MSCs are crucial components of the H. pylori infection-associated GC microenvironment, and may be critical for GC cell migration. In this study, an MSCs/H. pylori co-culture model was designed, and the effect of H. pylori-infected MSCs on the migration of GC cells was evaluated using a Transwell migration assay. H. pylori-infected MSC cytokine expression was evaluated using Luminex/ELISA. The expression of epithelial-mesenchymal transition (EMT) markers in the GC cells treated with supernatants from H. pylori-infected MSCs were detected by western blot analysis. The results demonstrated that the interaction between MSCs and H. pylori may induce GC cell migration, through secretion of a combination of cytokines that promote EMT in GC cells. The expression of phosphorylated forms of nuclear factor-κB (NF-κB) was observed to be increased in MSCs by H. pylori. Inhibition of NF-κB activation by pyrrolidine dithiocarbamate blocked the effects of H. pylori-infected MSCs on SGC-7901 human stomach adenocarcinoma cell migration. Overall, the results of the present study suggest that H. pylori-infected MSCs acquire a pro-inflammatory phenotype through secretion of a combination of multiple cytokines, a number of which are NF-κB-dependent. These cytokines enhance H. pylori infection-associated GC cell migration by promoting EMT in GC cells. The results of the present study provide novel evidence for the modulatory effect of MSCs in the tumor microenvironment and provide insight into the significance of stromal cell involvement in GC progression.
Transcatheter arterial embolization (TAE) is widely used as an effective palliative treatment for hepatocellular carcinoma (HCC), and can prolong survival time. However, the high incidence of tumor recurrence and metastasis after TAE is still a major problem. Recent studies demonstrated that circulating tumor cells (CTCs) contribute to tumor metastasis. In this study, we tried to clarify whether the residual HCC after TAE can increase metastasis by increasing the number of CTCs. An orthotopic liver tumor model in the Buffalo rat was established using green fluorescent protein (GFP)-transfected HCC cell line, McA-RH7777. Two weeks after orthotopic liver tumor implantation, the rats underwent TAE treatment from the gastroduodenal artery. Iodized oil or saline was injected intra-arterially. Blood samples were taken on day 0, 1, 3, 7, 14, and 21 for detection of CTCs after TAE treatment. We analyzed the number of CTCs and assessed the metastatic potential of surviving tumor cells in rats between TAE and control groups. Our results demonstrated that the metastatic colonies in the lung were significantly increased by TAE treatment. The number of CTCs was also significantly increased by TAE treatment from day 7 to day 21. The expression of hypoxia-inducible factor (HIF)-1α and epithelial-mesenchymal transition (EMT) marker proteins (N-cadherin and vimentin) was upregulated, but E-cadherin was downregulated after TAE treatment. In conclusion, the metastatic potential of residual HCC can be induced by TAE treatment in a rat liver tumor model, which involves the acquisition of EMT features and an increased number of CTCs.
Snail is closely linked to tumor invasion, metastasis, and recurrence and indicates prognosis of patients suffering from cancer. Overexpression of Snail increases motility and invasiveness of cancer cells, which has become target for anti-metastatic treatment. Oroxylin A, a natural compound extracted from Scutellaria radix, has been reported to inhibit invasion and migration in breast cancer. In this study, we investigated the anti-invasive effect of oroxylin A on lung cells and uncovered its underlying mechanism. The results suggested that oroxylin A could inhibit migration and invasion in Snail-expressing 95-D, and A549 cells whereas it had little effect on non-expressing GLC-82 cells. Furthermore, enhanced Snail expression after transfection of Snail vector in GLC-82 cells is decreased by oroxylin A. Snail can also induce epithelial-mesenchymal transition. We found oroxylin A could reverse TGFβ1-induced epithelial-mesenchymal transition by inhibiting Snail expression. As a result, oroxylin A up-regulated E-cadherin expression and down-regulated vimentin, MMP-9, and CD44v6 expression, which could lead to the inhibition of tumor migration and invasion. Mechanically, we demonstrated that oroxylin A suppressed activation of ERK instead of AKT pathway and then promoted activation of GSK-3β to reduce Snail protein content. Finally, we established transplanted, metastatic, and orthotopic models of A549 cells, and found that oroxylin A inhibited the growth and lung metastasis of A549 cells in vivo. Taken together, we proposed that oroxylin A might be a promising candidate targeting tumor metastasis.
© 2016 Wiley Periodicals, Inc.
Cancer related inflammation (CRI) is now recognized as the seventh hallmark in the pathogenesis of many types of malignancies. Paeonol, a natural phenolic component isolated from the root bark of Paeonia moutan, has significant anti-inflammatory activity. Recently, accumulating body of research has revealed potent anti-tumor effects mediated by paeonol. However, little is known about its anticancer mechanism on the basis of CRI. In this study, we observed that paeonol exerted direct anticancer activity through inhibition of cell proliferation, induction of apoptosis, and evident anti-inflammatory effects by reducing proinflammatory cytokines secretion (TNF-α, IL-1β, IL-6, and TGF-β) in the conditioned medium of B16F10 mouse melanoma cells. Interestingly, we found that paeonol significantly reversed motility phenotypes in TNF-α- or IL-6-induced B16F10 singe cell and collective migration and invasion in vitro, which were related to affecting epithelial-to-mesenchymal transition (EMT) makers and MMPs expression. In particular, paeonol disrupted both TNF-α-activated NF-κB and IL-6-activated STAT3 signaling pathways in B16F10 cells. EMSA and luciferase assays showed that paeonol abrogated NF-κB binding and NF-κB-driven promoter activity in the presence of TNF-α. Finally, we showed that paeonol attenuated B16F10 spontaneous lung metastases in C57/BL6J mice with down-regulated levels of serum proinflammatory cytokines. Therefore, paeonol possessed antitumor activity in melanoma cells and mice model by interruption of the aggressive feedback through proinflammatory cytokines mediated NF-κB and STAT3 signaling activation. These findings provide a novel treatment strategy that paeonol might be a promising versatile adjuvant therapy for cancer related inflammation.
Epithelial-mesenchymal transition (EMT) occurs during adult tissue remodeling responses including carcinogenesis and fibrosis. Existing evidence reveals that hepatocytes can undergo EMT in adult liver, which is critically involved in chronic liver injury. We herein established a hypoxia-induced EMT model in human LO2 hepatocytes treated with cobalt chloride (CoCl2) in vitro, and evaluated the effects of curcumin, a natural antifibrotic compound, on hepatocyte EMT and explored the underlying molecular mechanisms. We found that CoCl2 at non-toxic doses induced a mesenchymal cell phenotype in hepatocytes and upregulated several mesenchymal markers including α-smooth muscle actin, vimentin, N-cadherin, fibronectin and Snail (an EMT-related transcription factor), but downregulated the epithelial marker E-cadherin in hepatocytes. However, curcumin reversed the morphological changes, abrogated the increased expression of mesenchymal markers, and rescued E-cadherin expression in CoCl2-treated hepatocytes, suggesting the inhibition of hepatocyte EMT in vitro. We further found that curcumin interfered with the transforming growth factor-β (TGF-β) signaling by reducing the expression of TGF-β receptor I and inhibiting the expression and phosphorylation of Smad2 and Smad3. Use of SB431542, a specific inhibitor of TGF-β receptor I, demonstrated that interference with the TGF-β/Smad pathway was associated with curcumin suppression of hepatocyte EMT. Our in vivo data showed that curcumin affected hepatic EMT in rat fibrotic liver caused by carbon tetrachloride, which was associated with the inhibition of TGF-β/Smad signaling. These findings characterized a novel mechanism by which curcumin modulated hepatocyte EMT implicated in treatment of liver fibrosis.
Recent studies reveal that chemotherapy can enhance metastasis due to host responses, such as augmented expression of adhesion molecules in endothelial cells and increased populations of myeloid cells. However, it is still unclear how tumour cells contribute to this process. Here, we observed that paclitaxel and carboplatin accelerated lung metastasis in tumour-bearing mice, while doxorubicin and fluorouracil did not. Mechanistically, paclitaxel and carboplatin induced similar changes in cytokine and angiogenic factors. Increased levels of CXCR2, CXCR4, S1P/S1PR1, PlGF and PDGF-BB were identified in the serum or primary tumour tissues of tumour-bearing mice treated by paclitaxel. The serum levels of CXCL1 and PDGF-BB and the tissue level of CXCR4 were also elevated by carboplatin. On the other hand, doxorubicin and fluorouracil did not induce such changes. The chemotherapy-induced cytokine and angiogenic factor changes were also confirmed in gene expression datasets from human patients following chemotherapy treatment. These chemotherapy-enhanced cytokines and angiogenic factors further induced angiogenesis, destabilized vascular integrity, recruited BMDCs to metastatic organs and mediated the proliferation, migration and epithelial-to-mesenchymal transition of tumour cells. Interestingly, inhibitors of these factors counteracted chemotherapy-enhanced metastasis in both tumour-bearing mice and normal mice injected intravenously with B16F10-GFP cells. In particular, blockade of the SDF-1α-CXCR4 or S1P-S1PR1 axes not only compromised chemotherapy-induced metastasis but also prolonged the median survival time by 33.9% and 40.3%, respectively. The current study delineates the mechanism of chemotherapy-induced metastasis and provides novel therapeutic strategies to counterbalance pro-metastatic effects of chemo-drugs via combination treatment with anti-cytokine/anti-angiogenic therapy.
Glucose-regulated protein of 78kD (GRP78) is a multifunctional protein belonging to the heat shock protein 70 family. Overexpression of GRP78 triggered by environmental and physiological stresses is positively correlated with the occurrence and progression of various tumors, but the molecular mechanisms have not been well established. The present study indicated that overexpression of GRP78 in colon cancer cells could promote cell-matrix adhesion through the upregulation of fibronectin, integrin-β1 and phosphorylated FAK. Meanwhile, it resulted in a visible epithelial-mesenchymal transition in DLD1 cells, and the Snail-2 played the key role during the process. More importantly, the data indicated that GRP78 overexpression facilitated the expression and secretion of TGF-β1, which further activated the downstream Smad2/3 signaling module to effectuate the cell-matrix adhesion and epithelial-mesenchymal transition. Taken together, this study provides a novel molecular mechanism involving in the effects of GRP78 on colon cancer metastasis.
TGF-β1 secreted abundantly by tumors cells as well as present in the local microenvironment promotes neoplasm invasion and metastasis by triggering the epithelial to mesenchymal transition (EMT). MiR200c has been shown to suppress EMT and to regulate the cellular epithelial and interstitial state conversion, whereas the tumor vaccines are intended to specifically initiate or amplify a host response against evolving tumor cells. Our study aimed at optimizing the antitumor effects of the B16F10/glycosylphosphatidylinositol-interleukin 21 (B16F10/GPI-IL-21) tumor vaccine on melanoma bearing mice by combining the TGF-β1 knockdown and the administration of miR200c agomir. The mice were subcutaneously vaccinated with inactivated B16F10/GPI-IL-21 vaccine and challenged by B16F10 cells transfected with shTGF-β1 (B16F10/shTGF-β1 cells) or B16F10/shTGF-β1 cells with the administration of miR200c agomir. The later combination showed that, when compared with the mice in the control group that received no vaccination, vaccinated mice significantly increased NK and CTL activities, enhanced levels of IFN-γ, and reduced expression of TGF-β1, N-cadherin, Vimentin, Gli1/2, P-Smad2/3 and others involved in promoting expression of EMT-related molecules in tumor areas, and inhibited the melanoma metastasis in lungs and lymph nodes. Altogether, our findings demonstrate that this synergistic anti-cancer regimen effectively induces strong immune response and diminishes the melanoma progression.
Hairy enhancer of split-1 (HES1) is a transcriptional target of the Notch pathway, and a high level of HES1 is regarded as a marker of activated Notch. The aim of the study was to investigate the role of HES1 in colorectal cancer progression. We used tissue microarrays to analyze the expression and clinical significance of HES1 in 320 colorectal cancer samples. Stable overexpression and knockdown of HES1 were established in three colorectal cancer cell (CRC) lines (RKO, HCT8 and LOVO). We investigated the differentially expressed genes and enriched pathways in HES1 overexpressing CRC cells by gene expression profiling. Also, the role of HES1 in invasion and migration were examined in vitro and in vivo. We found that high expression of HES1 was significantly correlated with distal metastasis (P = 0.037) at diagnosis, and HES1 could serve as an unfavorable prognostic factor for colorectal cancer patients (P = 0.034). Gene expression profiling and pathway enrichment analysis revealed that HES1 was related to cellular adherens junction loss. In addition, we showed that HES1 overexpression lead to depressed E-cadherin, and elevated N-cadherin, vimentin and Twist-1 levels. Functionally, HES1 enhanced invasiveness and metastasis of CRC cells. HES1 promotes cancer metastasis via inducing epithelial mesenchymal transition and serves as a poor prognosis factor of colorectal cancer patients.
Metastasis is the leading cause of death in lung cancer. Understanding the mechanisms underlying the process of metastasis is crucial for identifying novel anti-metastatic therapies. Studies indicate that the highly conserved developmental pathways, such as the Wnt and Notch signaling pathways, play important roles in the non-small cell lung cancer (NSCLC) tumorigenesis. However, the roles of both pathways in NSCLC metastasis are unclear. The present study aimed to investigate whether Wnt3a and Notch3, key components of the Wnt and Notch signaling pathways, respectively, regulate the metastatic abilities of NSCLC cells and whether there is some relationship during these regulatory events. Here, we observed that Wnt3a treatment upregulated, not only the protein expression of Notch3, but also the mRNA expression of Notch3 and its downstream genes, HES1 and HEYL. In addition, Wnt3a promoted cell invasion and anchorage-independent growth. Meanwhile, Wnt3a treatment caused epithelial‑mesenchymal transition (EMT)-like morphological changes and F-actin reorganization. The western blotting data showed that Wnt3a treatment decreased the expression of E-cadherin and increased the expression of N-cadherin and vimentin. Compared with Wnt3a treatment, Notch3 shRNA transfection had opposite effects. Furthermore, Notch3 shRNA weakened the effects of Wnt3a treatment on the in vitro cell invasion and EMT. Overall, these observations suggest that Wnt3a and Notch3 may promote the metastasis of NSCLC and Notch3 upregulation is required for the Wnt3a mediated increased metastatic abilities of NSCLC.
Islet-cell autoantigen 69 kDa (ICA69) plays an important role in many diseases and physiological activities by forming heteromeric complexes with protein interacts with C-kinase 1 (PICK1). PICK1 is critical for inflammatory pain hypersensitivity by regulating trafficking of AMPA receptor subunit GluA2 in spinal neurons. However, the role of ICA69 in inflammatory pain has not yet been investigated. Here we reported that expression of PICK1 in spinal cord was reduced largely in ICA69 knockout mice. The pain hypersensitivity was enhanced in the second phase 7 days after formalin administration. Meanwhile, increased Ser880 phosphorylation in GluA2 and decreased surface GluA2 were concordant with the pain. Furthermore, the number of activated microglia in spinal dorsal horn increased in line with pain hypersensitivity. Together, ICA69 deficiency promoted the internalization of GluA2 and FML-induced long-lasting pain hypersensitivity. In addition, microglia activation might be an important factor in the development of the pain hypersensitivity.
The effect of proton pump inhibitor (PPI) on cancer risk has received much attention recently. In this study, we investigated the mechanism underlying multidrug resistance and the effect of a PPI pantoprazole using an adriamycin-resistant gastric cancer cell model (SGC7901/ADR). Compared with the parental cell line, SGC7901/ADR cells showed reduced proliferation rate, but higher resistance to adriamycin under both anchorage-dependent and -independent conditions. Notably, SGC7901/ADR cells underwent epithelial to mesenchymal transition (EMT) and showed increased migrating and invading capabilities. At molecular level, SGC7901/ADR cells showed strong activation of Wnt/β-catenin signaling pathway compared with parental sensitive cells. Interestingly, we found that a PPI pantoprazole can effectively reverse the aggressiveness and EMT marker expression of SGC7901/ADR cells. Furthermore, pantoprazole treatment resulted in a profound reduction of both total and phosphorylated forms of Akt and GSK-3β, which in turn suppressed the adriamycin-induced Wnt/β-catenin signaling in SGC7901/ADR cells. Taken together, we demonstrate that the aggressive phenotype of adriamycin-resistant SGC7901/ADR cells is mediated by induction of EMT and activation of the canonical Wnt/β-catenin signaling pathway. And for the first time, we show that it is possible to suppress the invasiveness of SGC7901/ADR cells by pantoprazole which targets the EMT and Akt/GSK-3β/β-catenin signaling.
Metastasis is the major cause of death in colorectal cancer (CRC). Although multiple genes have been identified to be responsible for the development of CRC, the molecular changes that enable CRC cells to undergo early local invasion and to form distant metastatic colonies still remain largely unknown. Herein, we investigated the role of Forkhead box protein C2 (FOXC2) and explored the underlying mechanisms in invasion and metastasis of CRC. We show that both high FOXC2 expression and nuclear localization of FOXC2 are significantly correlated with advanced TNM (T=primary tumor; N=regional lymph nodes; M=distant metastasis) stages. FOXC2 enhanced the invasive abilities of CRC cells in vitro and promoted local invasion and distant metastasis in an orthotopic mouse metastatic model of CRC. Microarray analysis revealed that overexpression of FOXC2 increased the proto-oncogene MET tyrosine kinase expression and activated the hepatocyte growth factor (HGF)-MET signaling pathway. Furthermore, luciferase reporter assays and chromatin immunoprecipitation assays revealed that FOXC2 directly associated with MET promoter to increase the transcriptional activity of MET. Inhibition of MET attenuates the invasive phenotype and metastatic potential of FOXC2-overexpressing CRC cells, indicating that MET is a major mediator of FOXC2-promoted metastasis. In addition, FOXC2 expression was positively correlated with MET expression in CRC tissue samples. Our findings suggest that FOXC2 has a crucial role in CRC metastasis by regulating HGF-MET signaling via inducing MET expression, highlighting FOXC2 as a potential therapeutic target for preventing or reducing metastasis in CRC.
Accumulating evidences implicate that ribonuclease inhibitor (RI) plays a suppressing role in cancer development. However, the mechanisms underlying antitumor of RI remain largely unknown. Epithelial-mesenchymal transition (EMT) is regarded as a key event in tumor progression. The reports have demonstrated that EMT was implicated in metastasis of bladder cancer. Therefore, we suppose that RI might involve regulating EMT of bladder cancer. Here bladder cancer T24 cells were transfected with pGensil-1-siRNA-RI vectors. HE staining, living cell observation, Phalloidine-FITC staining of microfilament, cell adhesion, scratch migration, and Matrigel invasion were examined respectively. RI expression and colocalization with ILK were detected using confocal microscope. Proteins associated with EMT were determined with Western blotting and immunohistochemistry in vivo and in vitro. Effects of RI expression on tumor growth, metastasis and EMT related proteins in BALB/C nude mouse and clinical human bladder cancer specimens were valued with histological, immunohistochemical and immunofluorescent examination respectively. We demonstrated that down-regulating RI increased cell proliferation, migration and invasion, changed cell morphology and adhesion, and rearranged cytoskeleton by inducing EMT and ILK signaling pathway in bladder cancer cells. In addition, we showed that down-regulating RI promoted tumorigenesis and metastasis of bladder cancer in vivo. Finally, we found that bladder cancer with invasive capability had higher Vimentin, Snail, Slug and Twist as well as lower E-cadherin and RI expression in clinical human specimens. Our results suggest that RI could play a novel role in inhibiting metastasis of bladder through regulating EMT and ILK signaling pathway.
Understanding the mechanisms of colorectal cancer (CRC) metastatic progression is essential to reducing its morbidity and mortality. Pyruvate kinase (PK) catalyses the final step of glycolysis and has been identified as a critical regulator of glucose consumption. However, the mechanisms and roles of PKM1 and PKM2 in the regulation of CRC cell migration and cell adhesion remain elusive. Here, we report that PKM2 rather than PKM1 drives CRC cell migration and cell adhesion, whereas PKM attenuation reverses these phenomena. Furthermore, the overexpression of PKM2 significantly increases the expression of N-cadherin, MMP-2, MMP-9, STAT3, Snail-2, pFAK and active β1-integrin, while E-cadherin expression is suppressed. More importantly, the results indicated that PKM2 overexpression facilitates STAT3 nuclear translocation, and it is required for PKM2 function in the regulation of migration and adhesion associated signalling. In addition, the dimeric form of PKM2, which lacks the pyruvate kinase activities but possesses protein kinase activity, is critical for CRC cell migration and cell adhesion. Overall, this study suggests that PKM2 overexpression promotes CRC cell migration and cell adhesion by regulating STAT3-associated signalling and that PKM2 may serve as a therapeutic target for CRC metastasis.
Tumor invasion and migration obstructs the treatment and prognosis of cancer. In this research, we investigated the effect of oroxylin A, a natural compound extracted from Scutellaria radix, the root of Scutellaria baicalensis, on inhibition of the invasion and migration of three different tumor cell lines: MCF-7, DU145, and HepG2. The results suggested that oroxylin A could inhibit hypoxia-induced migration and invasion of the three cell lines mentioned above. To study the detailed mechanisms, studies were carried out on MCF-7 cells and it was found that oroxylin A could regulate the expression of related markers in MCF-7 cells including E-cadherin, N-cadherin, and Vimentin. It was also found that oroxylin A inhibited the hypoxia-induced invasion and migration of MCF-7 cells by suppressing the Notch pathway. Oroxylin A inhibited N1ICD translocating to the nucleus and binding to epithelial-mesenchymal transition-related transcription factor Snail, thus suppressing the invasion and migration of MCF-7 cells. Therefore, oroxylin A is expected to be a promising candidate for antimetastasis treatment through suppression of the hypoxia-induced Notch pathway.
The epithelial-to-mesenchymal transient (EMT) is associated with tumor metastasis. Twist is one of the key transcription factors for EMT and relates to tumor cell migration. Long non-coding RNAs (lncRNAs) have recently emerged as important regulatory molecules involved in a broad range of biological processes and complicated diseases. However, it is unknown whether a signal network and lncRNAs are involved in Twist-induced EMT program. Taking MCF10A/Twist as a model, more than 99 lncRNAs and 3164 genes are regulated in the Twist-induced EMT process using lncRNA-array and cDNA micro-array. We establish a downstream signal network associated with EMT induced by Twist using bioinformatic analysis (Gene Ontology, pathway analysis) and experimental data. A set of multiple canonical signal pathways (such as WNT, MAPK, JAK/STAT, TGF-β, mTOR, Hedgehog and P53 signaling pathways) and several lncRNAs [such as lncRNA (chr6, 26124411-26139312, +), lncRNA (chr1, 41944445-41949874, -), lncRNA (chr17, 44833874-44834830, +)] are altered in MCF10A/Twist cells. More interestingly, lncRNA (chr17, 44833874-44834830, +), lncRNA (chr17, 21142183-21156578, -), lncRNA (chr6, 26124411-26139312, +) and lncRNA (chr19, 438420-2083745, -) may be involved in regulation or activation of WNT signaling pathway in the Twist-induced EMT process. These findings first determine that Twist contributes to invasion and metastasis by inducing wide-ranging transcriptional and functional changes of lncRNAs and signal pathways in our study.
Integrin-linked kinase (ILK) is a multifunctional serine/threonine kinase. Accumulating evidences suggest that ILK are involved in cell-matrix interactions, cell proliferation, invasion, migration, angiogenesis and Epithelial-mesenchymal transition (EMT). However, the underlying mechanisms remain largely unknown. EMT has been postulated as a prerequisite for metastasis. The reports have demonstrated that EMT was implicated in metastasis of oral squamous cell carcinomas. Therefore, here we further postulate that ILK might participate in EMT of tongue cancer. We showed that ILK siRNA inhibited EMT with low N-cadherin, Vimentin, Snail, Slug and Twist as well as high E-cadherin expression in vivo and in vitro. We found that knockdown of ILK inhibited cell proliferation, migration and invasion as well as changed cell morphology. We also demonstrated that ILK siRNA inhibited phosphorylation of downstream signaling targets Akt and GSK3β as well as reduced expression of MMP2 and MMP9. Furthermore, we found that the tongue tumor with high metastasis capability showed higher ILK, Vimentin, Snail, Slug and Twist as well as lower E-cadherin expression in clinical specimens. Finally, ILK siRNA led to the suppression for tumorigenesis and metastasis in vivo. Our findings suggest that ILK could be a novel diagnostic and therapeutic target for tongue cancer.
Human ribonuclease inhibitor (RI) is a cytoplasmic acidic protein possibly involved in biological functions other than the inhibition of RNase A and angiogenin activities. We have previously shown that RI can inhibit growth and metastasis in some cancer cells. Epithelial-mesenchymal transition (EMT) is regarded as the beginning of invasion and metastasis and has been implicated in the metastasis of bladder cancer. We therefore postulate that RI regulates EMT of bladder cancer cells. We find that the over-expression of RI induces the up-regulation of E-cadherin, accompanied with the decreased expression of proteins associated with EMT, such as N-cadherin, Snail, Slug, vimentin and Twist and of matrix metalloprotein-2 (MMP-2), MMP-9 and Cyclin-D1, both in vitro and in vivo. The up-regulation of RI inhibits cell proliferation, migration and invasion, alters cell morphology and adhesion and leads to the rearrangement of the cytoskeleton in vitro. We also demonstrate that the up-regulation of RI can decrease the expression of integrin-linked kinase (ILK), a central component of signaling cascades controlling an array of biological processes. The over-expression of RI reduces the phosphorylation of the ILK downstream signaling targets p-Akt and p-GSK3β in T24 cells. We further find that bladder cancer with a high-metastasis capability shows higher vimentin, Snail, Slug and Twist and lower E-cadherin and RI expression in human clinical specimens. Finally, we provide evidence that the up-regulation of RI inhibits tumorigenesis and metastasis of bladder cancer in vivo. Thus, RI might play a novel role in the development of bladder cancer through regulating EMT and the ILK signaling pathway.
MicroRNAs (miRNAs) have been believed to associate with malignant progression including cancer cell proliferation, apoptosis, differentiation, angiogenesis, invasion and metastasis. However, the functions of miRNAs are intricate, one miRNA can directly or indirectly target multiple genes and function as oncogene or tumor suppressor gene. In this study, we found that miR-21 inhibits PTEN and human sulfatase-1 (hSulf-1) expression in hepatocellular carcinoma (HCC) cells. The hSulf-1 is a heparin-degrading endosulfatase, which can inhibit the heparin binding growth factor-mediated signaling transduction into cells. Therefore, miR-21-mediated suppression of both hSulf-1 and PTEN led to activation of AKT/ERK pathways and epithelial-mesenchymal transition (EMT) in HCC cells, and finally enhance the activity of HCC cell proliferation and movement and promote HCC xenograft tumor growth in mouse models. These findings may provide candidate targets for prevention and treatment of HCC.
The inhibitor of apoptosis proteins (IAP) are closely correlated with proliferation, apoptosis, motility, and metastasis. Livin is the most recently identified IAP, and its role in breast progression remains unknown. In our study, analyses of 50 patients with breast cancer revealed that the positive expression rate of Livin was higher in breast cancer tissues (62%) relative to that in adjacent (35%) and normal tissues (25%). Livin expression in breast cancer correlated with the clinical stage and axillary lymph node metastasis and could be used as a prognostic marker. Our in vitro experiment revealed that Livin was highly expressed in high-invasive MDA-MB-231 cells as compared to low-invasive cells (MCF-7). Suppression of Livin by short-hairpin RNA reduced the Livin expression of MDA-MB-231 cells and subsequently inhibited tumor cell growth, proliferation, and colony formation and induced tumor cell apoptosis, motility, migration, and invasion. Overexpression of Livin in MCF7 cells resulted in increased migration and invasion capabilities of the cells without affecting proliferation and apoptosis. In addition, epithelial-mesenchymal transition (EMT) was induced by Livin expression in breast cancer cell lines. The high level of phosphorylated AKT in MDA-MB-231 cells was suppressed by Livin knockdown. Further, Livin-induced migration and invasion could be abolished by either the application of the phosphoinositide-3-kinase inhibitor LY294002 or knockdown of AKT expression using small-interfering RNA. In conclusion, Livin serves as an independent prognostic indicator for breast cancer. Livin expression promotes breast cancer metastasis through the activation of AKT signaling and induction of EMT in breast cancer cells both in vitro and in vivo.
Hypoxia-induced epithelial mesenchymal transition (EMT) is an essential step in cancer metastasis. Luteolin, a flavonoid that is widely distributed in plants, is a novel anticancer agent. However, the mechanism underlying its anticancer effects remains undefined. In this study, for the first time, we demonstrate that luteolin inhibits hypoxia-induced EMT in human non-small cell lung cancer cells in culture, which is demonstrated by the fact that hypoxia-induced EMT reduced the expression of E-cadherin and other epithelial markers and increased the expression of N-cadherin, vimentin and other mesenchymal markers; these effects were markedly attenuated by luteolin. In addition, luteolin also inhibited hypoxia-induced proliferation, motility and adhesion in the cells. Furthermore, we reveal that luteolin inhibits the expression of integrin β1 and focal adhesion kinase (FAK).Since integrin β1 and FAK signaling are closely related to EMT formation, these results suggest that luteolin inhibits hypoxia-induced EMT, at least in part, by inhibiting the expression of integrin β1 and FAK.
Human ribonuclease inhibitor (RI) is a cytoplasmic acidic protein. RI is constructed almost entirely of leucine rich repeats, which might be involved in unknown biological effects except inhibiting RNase A and angiogenin activities. We previously reported that up-regulating RI inhibited the growth and metastasis of melanoma cells. Epithelial-mesenchymal transition (EMT) is a critical event of cancer cells that triggers invasion and metastasis. However, the role of RI in the EMT process remains unknown. Here we hypothesize that RI might inhibit melanoma invasion and metastasis by regulating EMT. We found that over-expression of RI induced up-regulation of E-cadherin, accompanied with decreased expressions of proteins associated with EMT such as N-cadherin, Snail, Slug, Vimentin and Twist both in vitro and in vivo. Furthermore, RI restrained matrix metalloproteinase MMP-2 and MMP-9 secretions in B16 and B16-F10 melanoma cells. In addition, we also found that up-regulation of RI inhibited cell proliferation, migration and invasion as well as changed cell morphology, adhesion and rearranged cytoskeleton in vitro. Finally, the effects of RI on phenotype and invasiveness translated into suppressing metastasis by the experimental metastasis models of melanoma with lighter lung weight, a fewer metastasis nodules and a lower incidence rate, with respect to the control groups. Taken together, our data highlight, for the first time, that RI plays a novel role in inhibiting development and progression of murine melanoma cells through regulating EMT. These results suggest that RI could be a therapeutic target protein for melanoma and may be of biological importance.
BACKGROUND:
Genetically modified cells have been shown to be one of the most effective tumor vaccine strategies. However, in many cases, such as in melanoma, induction of a potent immune responses against the disease still remains a major challenge. Thus, novel strategies to reinforce tumor vaccine efficacy are needed. Using microRNA (miR) and Zinc-finger E-box binding homeobox (ZEB) have received much attention for potentially regulating tumor progression. To elicit a potent antitumor efficacy against melanoma, we used tumor vaccine in combination with miR200c overexpression or ZEB1 knockdown to assess the efficacy of treatment of murine melanoma.
METHODS:
B16F10 cell vaccine expressing interleukin 21 (IL-21) in the glycosylpho- sphatidylinositol (GPI)-anchored form (B16F10/GPI-IL-21) were developed. The vaccine was immunized into mice challenged by B16F10 cells or B16F10 cells stably transduced with lentiviral-miR200c (B16F10/miR200c) or transfected with the ZEB1-shRNA recombinant (B16F10/shZEB1) or the B16F10/GPI-IL-21 vaccine. The immune responses, tumorigenicity and lung metastasis in mice were evaluated, respectively.
RESULTS:
The vaccination with B16F10/GPI-IL-21 markedly increased the serum cytokine levels of IFN-γ, TNF-α, IL-4 and decreased TGF-β level as well as augmented the cytotoxicity of splenocytes in immunized mice compared with control mice. In addition, the tumor vaccine B16F10/GPI-IL-21 significantly inhibited the tumor growth and reduced counts of lung metastases in mice challenged by B16F10/GPI-IL-21, B16F10/shZEB1 and B16F10/miR200c respectively compared with the control mice challenged by B16F10 cells. The efficacy mechanisms may involve in reinforcing immune responses, increasing expression of miR200c, E-cadherin and SMAD-7 and decreasing expression of TGF-β, ZEB1, Vimentin and N-cadherin in tumor tissues from the immunized mice.
CONCLUSIONS:
These results indicate that the tumor vaccine B16F10/GPI-IL-21 in combination with miR200c overexpression or ZEB1 knockdown effectively inhibited melanoma growth and metastasis a murine model. Such a strategy may, therefore, be used for the clinical trials.
BACKGROUND:
Induction of epithelial-mesenchymal transition (EMT) is essential for the metastasis of tumor cells and maintaining their stemness. This study aimed to examine whether endothelial cells, which are most closely located to tumor cells in vivo, play a role in inducing EMT in tumor cells or not.
METHODS:
Concentrated culture medium of bovine aortic endothelial cells (BAECs) was applied to tumor cell lines (A549 and PANC-1) and epithelial cell line (NMuMg). Cadherin conversion, expressions of α-smooth muscle actin and ZO-1, actin fiber formation and cell migration were examined as hallmarks of the induction of EMT in these cell lines. Transforming growth factor β (TGFβ) antibodies were used to neutralize TGFβ1, TGFβ2 and TGFβ3. Expression and release of TGFβ proteins in BAECs as well as in porcine and human endothelial cells were assessed by Western blotting and ELISA, respectively.
RESULTS:
Conditioned medium of BAEC induced EMT in the examined cell lines. All endothelial cells from various species and locations expressed TGFβ1 and TGFβ2 proteins and much lower level of TGFβ3 protein. Conditioned medium from these endothelial cells contained TGFβ1 and TGFβ2, but TGFβ3 could not be detected. Neutralizing antibody against each of TGFβ1 or TGFβ2 did not reverse endothelium-dependent EMT, but simultaneous neutralization of both TGFβ1 and TGFβ2 completely abolished it.
CONCLUSIONS:
Endothelial cells may play a role in the induction and maintenance of EMT in tumor cells by constitutively releasing TGFβ1 and TGFβ2.
GENERAL SIGNIFICANCE:
The present results provide a novel strategy of the inhibition of tumor metastasis by targeting vascular endothelium.
Copyright © 2013 Elsevier B.V. All rights reserved.
AIM:
To investigate whether luteolin, a highly prevalent flavonoid, reverses the effects of epithelial-mesenchymal transition (EMT) in vitro and in vivo and to determine the mechanisms underlying this reversal.
METHODS:
Murine malignant melanoma B16F10 cells were exposed to 1% O(2) for 24 h. Cellular mobility and adhesion were assessed using Boyden chamber transwell assay and cell adhesion assay, respectively. EMT-related proteins, such as E-cadherin and N-cadherin, were examined using Western blotting. Female C57BL/6 mice (6 to 8 weeks old) were injected with B16F10 cells (1×10(6) cells in 0.2 mL per mouse) via the lateral tail vein. The mice were treated with luteolin (10 or 20 mg/kg, ip) daily for 23 d. On the 23rd day after tumor injection, the mice were sacrificed, and the lungs were collected, and metastatic foci in the lung surfaces were photographed. Tissue sections were analyzed with immunohistochemistry and HE staining.
RESULTS:
Hypoxia changed the morphology of B16F10 cells in vitro from the cobblestone-like to mesenchymal-like strips, which was accompanied by increased cellular adhesion and invasion. Luteolin (5-50 μmol/L) suppressed the hypoxia-induced changes in the cells in a dose-dependent manner. Hypoxia significantly decreased the expression of E-cadherin while increased the expression of N-cadherin in the cells (indicating the occurrence of EMT-like transformation), which was reversed by luteolin (5 μmol/L). In B16F10 cells, luteolin up-regulated E-cadherin at least partly via inhibiting the β3 integrin/FAK signal pathway. In experimental metastasis model mice, treatment with luteolin (10 or 20 mg/kg) reduced metastatic colonization in the lungs by 50%. Furthermore, the treatment increased the expression of E-cadherin while reduced the expression of vimentin and β3 integrin in the tumor tissues.
CONCLUSION:
Luteolin inhibits the hypoxia-induced EMT in malignant melanoma cells both in vitro and in vivo via the regulation of β3 integrin, suggesting that luteolin may be applied as a potential anticancer chemopreventative and chemotherapeutic agent.
