Search

Background: The relation between tumor-infiltrating macrophages and tumor cell migration/invasion toward blood vessels remained unclear. Results: Macrophage induced the endothelin-integrin axis to stimulate breast cancer cell chemotaxis and adhesion toward endothelial cells and transendothelial migration. Conclusion: Our data suggest how macrophages affect cancer cell interactions with endothelial cells. Significance: The endothelin-integrin axis has a pivotal role in breast cancer microenvironment. Elevated macrophage infiltration in tumor tissues is associated with breast cancer metastasis. Cancer cell migration/invasion towards angiogenic microvasculature is a key step in metastatic spread. We therefore studied how macrophages stimulated breast cancer cell interactions with endothelial cells. Macrophages produced cytokines such as interleukin-8 and tumor necrosis factor-α to stimulate endothelin (ET) and ET receptor (ETR) expression in breast cancer cells and human umbilical vascular endothelial cells (HUVECs). ET-1 was induced to a greater extent from HUVECs than breast cancer cells, resulting in a density difference that facilitated cancer cell chemotaxis toward HUVECs. Macrophages also stimulated breast cancer cell adhesion to HUVECs and transendothelial migration, which were repressed by ET-1 antibody or ETR inhibitors. The ET axis induced integrins such as αV and β1 and their counter-ligands such as intercellular adhesion molecule-2 and P-selectin in breast cancer cells and HUVECs, and antibodies against these integrins efficiently suppressed macrophage-stimulated breast cancer cell interactions with HUVECs. ET-1 induced Ets-like kinase-1 (Elk-1), signal transducer and activator of transcription-3 (STAT-3), and nuclear factor-κB (NF-κB) phosphorylation in breast cancer cells. Use of inhibitors to prevent their phosphorylation, or ectopic overexpression of dominant-negative IκBα, perturbed ET-1-induced integrin αV and integrin β1 expression. The physical associations of these three transcriptional factors with the gene promoters of the two integrins were furthermore evidenced by chromatin immunoprecipitation assay. Finally, our mouse orthotopic tumor model revealed an ET axis-mediated lung metastasis of macrophage-stimulated breast cancer cells, supporting that the ET axis was involved in macrophage-enhanced breast cancer cell endothelial interactions. [ABSTRACT FROM AUTHOR]

Secreted levels of HSP90α and overexpression of TCF12 have been associated with the enhancement of colorectal cancer (CRC) cell migration and invasion. In this study, we observed that CRC patients with tumor TCF12 overexpression exhibited both a higher rate of metastatic occurrence and a higher average serum HSP90α level compared with patients without TCF12 overexpression. Therefore, we studied the relationship between the actions of secreted HSP90α and TCF12. Like overexpressed TCF12, secreted HSP90α or recombinant HSP90α (rHSP90α) induced fibronectin expression and repressed E-cadherin, connexin-26, connexin-43, and gap junction levels in CRC cells. Consistently, rHSP90α stimulated invasive outgrowths of CRC cells from spherical structures during three-dimensional culture. rHSP90α also induced TCF12 expression in CRC cells. Its effects on CRC cell epithelial-mesenchymal transition, migration, and invasion were drastically prevented when TCF12 was knocked down. This suggests that TCF12 expression is required for secreted HSP90α to enhance CRC cell spreading. Through the cellular receptor CD91, rHSP90α facilitated the complex formation of CD91 with IκB kinases (IKKs) α and β and increased the levels of phosphorylated (active) IKKα/β and NF-κB. Use of an IKKα/β inhibitor or ectopic overexpression of dominant-negative IκBα efficiently repressed rHSP90α-induced TCF12 expression. Moreover, κB motifs were recognized in the gene sequence of theTCF12 promoter, and a physical association between NF-κB and the TCF12promoter was detected in rHSP90α-treated CRC cells. Together, these results suggest that the CD91/IKK/NF-κB signaling cascade is involved in secreted HSP90α-induced TCF12 expression, leading to E-cadherin down-regulation and enhanced CRC cell migration/invasion. [ABSTRACT FROM AUTHOR]

A correlation of TCF12mRNA overexpression with colorectal cancer (CRC) metastasis was suggested by microarray data and validated by the survey of 120 patients. Thirty-three (27.5%) of the 120 patients showed tumor TCF12 mRNA overexpression and had a higher rate of metastatic occurrence (p=0.020) and a poorer survival outcome (p = 0.014). Abundant TCF12 levels were also observed in human CRC cell lines such as SW620 and LoVo, but a relatively low level was detected in SW480 cells. Knockdown of TCF12 expression in SW620 and LoVo cells drastically reduced their activities of migration, invasion, and metastasis. Tight cell-cell contact and an increase in E-cadherin but a concomitant decrease in fibronectin were observed in TCF12-knockdown cells. Connexin 26, connexin 43, and gapjunction activity were also increased upon TCF12-knockdown. In contrast, ectopic TCF12 overexpression in SW480 cells facilitated fibronectin expression and cell migration and invasion activities but diminished cellular levels of E-cadherin, connexin 26, connexin 43, and gap junction. A physical association of TCF12 with the E-cadherin promoter was evidenced by chromatin immunoprecipitation assay. TCF12 was tightly correlated with cellular expression of Bmi1 and EZH2 and was co-immunoprecipitable with Bmi1 and EZH2, suggesting that TCF12 transcriptionally suppressed E-cadherin expression via polycomb group-repressive complexes. Clinically, TCF12 mRNA overexpression was also correlated with E-cadherin mRNA down-regulation in the tumor tissues of our 120 patients (p = 0.013). These studies suggested that TCF12 functioned as a transcriptional repressor of E-cadherin and its overexpression was significantly correlated with the occurrence of CRC metastasis. [ABSTRACT FROM AUTHOR]

HCT-8 colon cancer cells secreted heat shock protein 90α (HSP90α) and had increased invasiveness upon serum starvation. The concentrated conditioned medium of serum-starved HCT-8 cells was able to stimulate the migration and invasion non-serum-starved cells, which could be prevented by treatment with an anti-HSP90α antibody. Recombinant HSP90α (rHSP90α) also enhanced HCT-8 cell migration and invasion, suggesting a stimulatory role of secreted HSP90α in cancer malignancy. HSP90α binding to CD91 α and Neu was evidenced by the proximity ligation assay, and rHSP90α-induced HCT cell invasion could be suppressed by the addition of anti-CD91 or anti-Neu antibodies. Via CD91α and Neu, rHSP90α selectively induced integrin αv expression, and knockdown of integrin αv efficiently blocked rHSP90α-induced HCT-8 cell invasion. rHSP90α induced the activities of ERK, PI3K/Akt, and NF-κB p65, but only NF-κB activation was involved in HSP90α-induced integrin αv expression. Additionally, we investigated the serum levels of HSP90α and the expression status of tumor integrin αv mRNA in colorectal cancer patients. Serum HSP90α levels of colorectal cancer patients were significantly higher than those of normal volunteers (p < 0.001). Patients with higher serum HSP90α levels significantly exhibited elevated levels of integrin αv mRNA in tumor tissues as compared with adjacent non-tumor tissues (p < 0.001). Furthermore, tumor integrin αv overexpression was significantly correlated with TNM (Tumor, Node, Metastasis) staging (p = 0.001). [ABSTRACT FROM AUTHOR]