Li-Li Chen

Secreted heat shock protein 90α induces colorectal cancer cell invasion through CD91/LRP-1 and NF-κB-mediated integrin αV expression

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 of 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 CD91α and Neu was evidenced by the proximity ligation assay, and rHSP90α-induced HCT-8 cell invasion could be suppressed by the addition of anti-CD91α 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).

TCF12 Protein Functions as Transcriptional Repressor of E-cadherin, and Its Overexpression Is Correlated with Metastasis of Colorectal Cancer

A correlation of TCF12 mRNA 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 gap-junction 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.

Secreted Heat Shock Protein 90α (HSP90α) Induces Nuclear Factor-κB-mediated TCF12 Protein Expression to Down-regulate E-cadherin and to Enhance Colorectal Cancer Cell Migration and Invasion

Background: Both secreted HSP90α and overexpressed TCF12 enhance colorectal cancer (CRC) cell migration/invasion. Results: Secreted HSP90α induces the CD91/IκB kinase/NF-κB/TCF12 cascade to down-regulate E-cadherin and to enhance CRC cell migration/invasion. Conclusion: Secreted HSP90α acts through TCF12 expression to enhance CRC cell spreading. Significance: Secreted HSP90α contributes to tumor TCF12 overexpression and can be a therapeutic target of CRC. 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 the TCF12 promoter, and a physical association between NF-κB and the TCF12 promoter 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.

Tumor Necrosis Factor-α, Interleukin-8 and Interleukin-6 Are Involved in Vascular Endothelial Cell Capillary Tube and Network Formation Induced by Tumor-Associated Macrophages

AIM: The goal of this study is to investigate the involvement of inflammatory cytokines produced by tumor-associated macrophages in promoting tumor angiogenesis. METHODS: To study the angiogenic effect of tumor-associated macrophages (TAMs), we overlaid human umbilical vein endothelial cells on top of Matrigel containing MCF-7 breast cancer cells with or without macrophages and investigated the outcome of endothelial cell capillary tube and network formation. We also determined the levels of interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-12p70, tumor necrosis factor-α (TNF-α), and vascular endothelial growth factor (VEGF) in the media of MCF-7 breast cancer cells co-cultivated with or without macrophages. Furthermore, anti-IL-8 receptor antagonizing antibody, IL-6 or TNF-α soluble receptor, and inhibitors against NF-κB, MEK, p38 MAPK , and JNK, respectively, were used to determine which signal transduction pathways are involved in TAMs-induced angiogenic activity. RESULTS: The Matrigel mixed with MCF-7 cells and macrophages was more efficient than 100 ng/ml of VEGF to induce vascular endothelial cell tube and network formation. The expression of IL-6, IL-8 and TNF-α were significantly enhanced by cocultivation of MCF-7 cells with macrophages. The promotion of capillary tube and network formation by TAMs was inhibited either with anti-IL-8 receptor antagonizing antibody or with IL-6 or TNF-α soluble receptor, suggesting that IL-8, TNF-α and IL-6 indeed participated in TAMs-induced angiogenesis. In addition, TAMs-induced angiogenic activity could also be attenuated by the presence of inhibitors against NF-κB, ERK, and p38 MAPK

The Endothelin-Integrin Axis Is Involved in Macrophage-Induced Breast Cancer Cell Chemotactic Interactions with Endothelial Cells

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 toward 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 from 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 counterligands, 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. The 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 a chromatin immunoprecipitation assay. Finally, our mouse orthotopic tumor model revealed an ET axis-mediated lung metastasis of macrophage-stimulated breast cancer cells, suggesting that the ET axis was involved in macrophage-enhanced breast cancer cell endothelial interactions.

Osteopontin–integrin engagement induces HIF-1α–TCF12-mediated endothelial-mesenchymal transition to exacerbate colorectal cancer

Osteopontin (OPN) is a multi-functional phospho-glycoprotein that can stimulate angiogenesis through acting on endothelial cells. As angiogenic sprouting involves endothelial-to-mesenchymal transition (EndoMT), we are intrigued to know whether OPN exerts an effect on EndoMT. Clinically, we indeed detected EndoMT-derived cells next to OPN-expressing cells in colorectal cancer tissues. Furthermore, we treated OPN to primary cultures of endothelial cells to investigate the EndoMT-inducing activity and the underlying mechanisms. Integrin αVβ3 rather than CD44 is involved in OPN-induced EndoMT. OPN-integrin αVβ3 engagement induces HIF-1α expression through a PI3K/Akt/TSC2-mediated and mTORC1-dependent protein synthesis pathway, which in turn trans-activates TCF12 gene expression. TCF12 further interacts with EZH2 and histone deacetylases to transcriptionally repress VE-cadherin gene and thus facilitates EndoMT. Like cancer-associated fibroblasts, EndoMT-derived cells promote tumor growth and metastasis by secreting certain proteins. Secreted HSP90α is a candidate suggested by microwestern array assay, and is herein verified to induce stemness properties in colorectal cancer cells. As OPN is overexpressed in human cancers, OPN-induced EndoMT and EndoMT-derived cells can be potentially taken as cancer therapeutic targets.

Myeloid-derived macrophages and secreted HSP90α induce pancreatic ductal adenocarcinoma development

ABSTRACT We detected a significant elevation of serum HSP90α levels in pancreatitis patients and even more in pancreatic ductal adenocarcinoma (PDAC) patients. However, there was no significant difference in the serum HSP90α levels between patients with early-stage and late-stage PDAC. To study whether elevation of serum HSP90α levels occurred early during PDAC development, we used LSL-KrasG12D/Pdx1-Cre transgenic mice as a studying model. Elevated serum HSP90α levels were detected before PDAC formation and an extracellular HSP90α (eHSP90α) inhibitor effectively prevented PDAC development. Both serum HSP90α level and pancreatic lesion were suppressed when the mice were administered a CD11b-antagonizing antibody, suggesting that CD11b+-myeloid cells were associated with eHSP90α levels and pancreatic carcinogenesis. Consistently, in CD11b-DTR-EGFP transgenic mouse model with CD11b+-myeloid cells depletion, serum HSP90α levels were suppressed and Panc-02 cell grafts failed to develop tumors. Macrophages and granulocytes are two common tissue-infiltrating CD11b+-myeloid cells. Duplex in situ hybridization assays suggested that macrophages were predominant HSP90α-expressing CD11b+-myeloid cells during PDAC development. Immunohistochemical and immunohistofluorescent staining results revealed that HSP90α-expressing cells included not only macrophages but also pancreatic ductal epithelial (PDE) cells. Cell culture studies also indicated that eHSP90α could be produced by macrophages and macrophage-stimulated PDE cells. Macrophages not only secreted significant amount of HSP90α, but also secreted interleukin-6 and interleukin-8 to induce a JAK2−STAT3 signaling axis in PDE cells, stimulating them to express and secrete HSP90α. eHSP90α further promoted cellular epithelial-mesenchymal transition, migration, and invasion in PDE cells. Besides myeloid cells, eHSP90α can be potentially taken as a target to suppress PDAC pathogenesis.