S100P interacts with integrin α7 and increases cancer cell migration and invasion in lung cancer

S100P, a Ca2⁺ binding protein, has been shown to be overexpressed in various cancers. However, its functional character in lung cancer remains largely unknown. In this study, we show that S100P increases cancer migration, invasion and metastasis in lung cancer cells. Ectopic expression of S100P increases migration, invasion and EMT in less invasive CL1-0 lung cancer cells. Conversely, knockdown of S100P suppressed migration and invasion, and caused a reversion of EMT in highly invasive lung cancer cells. These effects were transduced by increasing the interaction of S100P with integrin α7, which activated focal adhesion kinase (FAK) and AKT. Blocking FAK significantly decreased S100P-induced migration by decreasing Src and AKT activation, whereas inhibiting AKT reduced S100P upregulation on ZEB1 expression. Further study has indicated that S100P knockdown prevents the spread of highly metastatic human lung cancer in animal models. This study therefore suggests that S100P represents a critical activator of lung cancer metastasis. Detection and targeted treatment of S100P-expressing cancer is an attractive therapeutic strategy in treating lung cancer.     

TGFβ-induced phosphorylation of Par6 promotes migration and invasion in prostate cancer cells

Background:

The Par complex – comprising partition-defective 6 (Par6), Par3, and atypical protein kinase C (aPKC) – is crucial for cell polarisation, the loss of which contributes to cancer progression. Transforming growth factor β (TGFβ)-induced phosphorylation of Par6 on the conserved serine 345 is implicated in epithelial-to-mesenchymal transition (EMT) in breast cancer. Here we investigated the importance of phosphorylated Par6 in prostate cancer.

Methods:

We generated a p-Par6³⁴⁵-specific antibody and verified its specificity in vitro. Endogenous p-Par6³⁴⁵ was analysed by immunoblotting in normal human prostate RWPE1 and prostate cancer (PC-3U) cells. Subcellular localisation of p-Par6³⁴⁵ in migrating TGFβ-treated PC-3U cells was analysed by confocal imaging. Invasion assays of TGFβ-treated PC-3U cells were performed. p-Par6 expression was immunohistochemically analysed in prostate cancer tissues.

Results:

TGFβ induced Par6 phosphorylation on Ser345 and its recruitment to the leading edge of the membrane ruffle in migrating PC-3U cells, where it colocalised with aPKCζ. The p-Par6–aPKCζ complex is important for cell migration and invasion, as interference with this complex prevented prostate cancer cell invasion. High levels of activated Par6 correlated with aggressive prostate cancer.

Conclusions:

Increased p-Par6Ser³⁴⁵ levels in aggressive prostate cancer tissues and cells suggest that it could be a useful novel biomarker for predicting prostate cancer progression.     

TNF-α promotes breast cancer cell migration and enhances the concentration of membrane-associated proteases in lipid rafts

Purpose

Tumor progression is associated with cell migration, invasion and metastasis. These processes are accompanied by the activation of specific proteases that are either linked to cellular membranes or are secreted into extracellular spaces. TNF-α is known to play an important role in various aspects of tumor progression. The aim of this work was to assess the effect of TNF-α on the migration of breast cancer cells and, in addition, to assess its association with the location of membrane-associated proteases in lipid rafts.

Methods

Wound scratch healing and Transwell migration assays were used to study the effect of TNF-α on the migration of both hormone-dependent and hormone-independent breast cancer-derived cells, i.e., MCF7 and MDA-MB-231, respectively. The expression and secretion of three matrix metalloproteases, MMP9, MMP2 and MT1-MMP, and two dipeptidyl peptidases, CD26 and FAP-α, was investigated using RT-PCR, Western blotting and gelatin zymography. In addition, activation of the MAPK/ERK signaling pathway was investigated by Western blotting.

Results

We found that a TNF-α-induced enhancement of breast cancer cell migration was accompanied by an increased secretion of MMP9, but not MMP2, into the culture media. We also found that TNF-α upregulated the expression of the dipeptidyl peptidases CD26 and FAP-α in a dose-dependent manner and, in addition, enhanced the concentration of all five proteases in lipid rafts in the breast cancer-derived cells tested, regardless of cell type. Furthermore, we found that TNF-α activated the MAPK/ERK signaling pathway by increasing the ERK1/2 phosphorylation level. Application of the MEK/ERK1/2 inhibitor U-0126 resulted in down-regulation of TNF-α-induced MMP9 secretion and abrogation of the enhanced concentration of proteases in the lipid rafts.

Conclusions

From our results we conclude that TNF-α-induced activation of the MAPK/ERK signaling pathway may promote breast cancer cell migration via both upregulation of MMP9, CD26 and FAP-α and concentration of these proteases, as also MT1-MMP and MMP2, in the lipid rafts. TNF-α may serve as a potential therapeutic target in breast cancers susceptible to TNF-α stimulation.

     

Ligand-activated PPARδ modulates the migration and invasion of melanoma cells by regulating Snail expression

Peroxisome proliferator-activated receptor (PPAR) δ is implicated in the carcinogenesis of several types of cancer. However, the therapeutic efficacy of PPARδ ligands against cancer progression is unclear. Here, we showed that PPARδ modulates the migration and invasion of melanoma cells by up-regulating Snail expression. Activation of PPARδ by {"type":"entrez-nucleotide","attrs":{"text":"GW501516","term_id":"289075981","term_text":"GW501516"}}GW501516, a specific ligand for PPARδ, significantly increased the migration and invasion of highly metastatic A375SM cells, but not that of low metastatic A375P cells. The migration- and invasion-promoting effects of PPARδ on A375SM cells was associated with increased Snail expression, which was accompanied by a decrease in E-cadherin expression. Furthermore, a significant concentration- and time-dependent increase in the levels of Snail mRNA and protein was observed in A375SM cells (but not A375P cells) treated with {"type":"entrez-nucleotide","attrs":{"text":"GW501516","term_id":"289075981","term_text":"GW501516"}}GW501516. The effects of {"type":"entrez-nucleotide","attrs":{"text":"GW501516","term_id":"289075981","term_text":"GW501516"}}GW501516 were almost completely abrogated by a small interfering RNA against PPARδ, suggesting that PPARδ mediates the effects of {"type":"entrez-nucleotide","attrs":{"text":"GW501516","term_id":"289075981","term_text":"GW501516"}}GW501516. Activation of PPARδ in SK-MEL-2 and SK-MEL-5 (but not SK-MEL-3) melanoma cell lines also led to significant increases in the expression of Snail mRNA and protein, which mirrored the invasive and migratory potential of these cell lines. These results suggest that PPARδ promotes the aggressive phenotype observed in highly metastatic melanoma cells by up-regulating Snail.     

Involvement of NF-κB-mediated expression of galectin-3-binding protein in TNF-α-induced breast cancer cell adhesion

Galectin-3-binding protein (G3BP) is highly expressed in various types of cancer and is thought to be involved in cancer malignancy; however, the role of G3BP in breast cancer cells is not fully understood. In this study, we investigated the role of NF-κB in the adhesion of breast cancer cells to a substrate by using (-)-DHMEQ, a specific inhibitor of NF-κB. (-)-DHMEQ inhibited both TNF-α-induced G3BP expression and cell adhesion in human breast cancer cell lines. We also found that knockdown of G3BP suppressed the adhesion, while its overexpression increased the adhesion. These data reveal that (-)-DHMEQ suppresses breast cancer cell adhesion by inhibiting NF-κB-regulated G3BP expression.     

Transient gene silencing of galectin-3 suppresses pancreatic cancer cell migration and invasion through degradation of β-catenin

Pancreatic cancer is a leading cause of cancer-related mortality and often has a poor prognosis because of its late diagnosis, aggressive local invasion, early metastasis and poor response to chemotherapy. The chemotherapeutic agent gemcitabine is effective for treating advanced pancreatic cancer, but its efficacy remains less than satisfactory. It is expected that further investigation of pancreatic cancer cell invasion and development of strategies to block this process should improve the disease prognosis. In this study, we tested our hypothesis that galectin-3 (gal-3), a multifunctional member of the β-galactoside-binding protein family, may regulate pancreatic cancer cell motility and silencing of it inhibit cell motility. Previous studies demonstrated that this protein is associated with tumor cell adhesion, proliferation, differentiation, angiogenesis, apoptosis and metastasis. Here, we used gal-3 small interfering RNA (siRNA) to silence its expression in various pancreatic cancer cell lines to determine whether gal-3 regulates cell proliferation, migration and invasion in vitro. We found that silencing gal-3 reduced cellular migration and invasion, but failed to affect proliferation. In gal-3 siRNA-transfected cells, we detected a decrease in β-catenin expression, an important signal for cancer cell invasion, which was caused by downregulation of phosphorylated Akt and GSK-3β. We also found that matrix metalloproteinase (MMP)-2 expression was reduced by gal-3 silencing. These results indicate that gal-3-mediated invasion via MMP-2 regulated by β-catenin degradation is initiated by Akt phosphorylation in pancreatic cancer cells. Our results suggest that gal-3 can be a novel therapeutic target in pancreatic cancer.     

Human FAT1 cadherin controls cell migration and invasion of oral squamous cell carcinoma through the localization of β-catenin

FAT1 [Homo sapiens FAT tumor suppressor homolog?1 (Drosophila)] is an intrinsic membrane protein classified as a member of the cadherin superfamily. The FAT1 gene is a tumor suppressor in humans as well as being the pivotal gene for cell morphogenesis and migration. Deletion of this gene could play a role in the characteristics of oral squamous cell carcinomas (OSCCs), involving cell adhesion, migration and/or invasion. This study investigated the mechanisms by which FAT1 is involved in the biological behavior of OSCCs. First, a rat monoclonal antibody was developed against a FAT1 intra-cellular domain epitope, and used for an immunohistochemical study of FAT1 in clinically obtained OSCC samples. FAT1 was localized at lamellipodial edges or cell-cell boundaries in normal cells and well differentiated OSCCs, but showed a diffuse cytoplasmic and nuclear distribution in moderately-poorly differentiated OSCCs. FAT1-siRNA was transfected into OSCCs resulting in a drastic inhibition of cell migration and invasion based on the suppression of FAT1 expression and disorganized localization of β-catenin which is associated with cell polarity and migration. These results suggested that FAT1 may be involved in the migration and invasion mechanisms of OSCCs and, therefore, it could be an important target for the development of new therapeutic strategies.     

α-Mangostin inhibits hypoxia-driven ROS-induced PSC activation and pancreatic cancer cell invasion

Recent advances indicating a key role of microenvironment for tumor progression, we investigated the role of PSCs and hypoxia in pancreatic cancer aggressiveness, and examined the potential protective effect of α-mangostin on hypoxia-driven pancreatic cancer progression. Our data indicate that hypoxic PSCs exploit their oxidative stress due to hypoxia to secrete soluble factors favouring pancreatic cancer invasion. α-Mangostin suppresses hypoxia-induced PSC activation and pancreatic cancer cell invasion through the inhibition of HIF-1α stabilization and GLI1 expression. Increased generation of hypoxic ROS is responsible for HIF-1α stabilization and GLI1 upregulation. Therefore, α-mangostin may be beneficial in preventing hypoxia-induced pancreatic cancer progression.     

Tumour-suppressive microRNA-29s inhibit cancer cell migration and invasion by targeting laminin–integrin signalling in head and neck squamous cell carcinoma

Background:

Our recent studies of microRNA (miRNA) expression signatures demonstrated that microRNA-29s (miR-29s; miR-29a/b/c) were significantly downregulated in head and neck squamous cell carcinoma (HNSCC) and were putative tumour-suppressive miRNAs in human cancers. Our aim in this study was to investigate the functional significance of miR-29s in cancer cells and to identify novel miR-29s-mediated cancer pathways and responsible genes in HNSCC oncogenesis and metastasis.

Methods:

Gain-of-function studies using mature miR-29s were performed to investigate cell proliferation, migration and invasion in two HNSCC cell lines (SAS and FaDu). To identify miR-29s-mediated molecular pathways and targets, we utilised gene expression analysis and in silico database analysis. Loss-of-function assays were performed to investigate the functional significance of miR-29s target genes.

Results:

Restoration of miR-29s in SAS and FaDu cell lines revealed significant inhibition of cancer cell migration and invasion. Gene expression data and in silico analysis demonstrated that miR-29s modulated the focal adhesion pathway. Moreover, laminin γ2 (LAMC2) and α6 integrin (ITGA6) genes were candidate targets of the regulation of miR-29s. Luciferase reporter assays showed that miR-29s directly regulated LAMC2 and ITGA6. Silencing of LAMC2 and ITGA6 genes significantly inhibited cell migration and invasion in cancer cells.

Conclusion:

Downregulation of miR-29s was a frequent event in HNSCC. The miR-29s acted as tumour suppressors and directly targeted laminin–integrin signalling. Recognition of tumour-suppressive miRNA-mediated cancer pathways provides new insights into the potential mechanisms of HNSCC oncogenesis and metastasis and suggests novel therapeutic strategies for the disease.     

KIN17 promotes cell migration and invasion through stimulating the TGF-β/Smad2 pathway in hepatocellular carcinoma

KIN17 DNA and RNA binding protein (Kin17) is involved in the regulation of tumorigenesis of diverse human cancers. However, its role in the cancer progression and metastasis in hepatocellular carcinoma (HCC) remains largely unknown. Bioinformatics and immunohistochemistry staining were used to investigate the expression pattern of KIN17 and its prognostic value in HCC patients. The transwell, wound-healing assay was employed to determine the effects of KIN17 on migration and invasion of HCC cells in vitro. The tail veins model was employed to determine the effects of KIN17 on lung metastasis in vivo. The biological mechanisms involved in cell migration and invasion regulated by KIN17 were determined with Western blot analysis method. KIN17 expression was significantly increased in HCC tissues compared with adjacent normal tissues, with particularly higher in portal vein tumor thrombus and intrahepatic metastasis tissues. Patients with higher KIN17 expression experienced poor overall and disease free survival. KIN17 knockdown in HuH7 and HepG2 cells significantly reduced cell migration and invasion abilities, whereas its overexpression promoted migration and invasion in MHCC-97L and HepG2 cells in vitro and in vivo. In HuH7 and HepG2 cells, KIN17 knockdown inhibited the TGF-β/Smad2 pathway. In contrast, KIN17 overexpression stimulated TGF-β/Smad2 pathway in MHCC-97L and HepG2 cells, along with the genes involved in the epithelial-mesenchymal transition. These findings suggest that KIN17 promotes migration and invasion in HCC cells by stimulating the TGF-β/Smad2 pathway. KIN17 could be a promising prognostic biomarker, as well as a potential therapeutic target in HCC.     

Involvement of PKCα activation in TF/VIIa/PAR2-induced proliferation, migration, and survival of colon cancer cell SW620

Our previous study has demonstrated that protease-activated receptor 2 (PAR2) activation mediated by tissue factor (TF)/VIIa complex triggers the ERK1/2/NF-κB signaling pathway, which further contributes to the proliferation and migration of colon cancer cell line SW620. However, the detailed mechanisms remain unclear. This study was to investigate whether protein kinase Cα (PKCα) is involved in these events and the possible mechanism. The results revealed that PAR2-activating peptide or VIIa could induce time-dependent upregulation of PKCα phosphorylation in SW620 cells and PKCα translocation from the cytoplasm to the perinuclear region and nucleus. The activation of PKCα was sufficient to induce ERK1/2 and NF-κB phosphorylation. The VIIa effect was obviously blocked by both anti-TF and anti-PAR2 antibodies. The PKCα inhibitor, safingol, inhibited ERK1/2 phosphorylation and NF-κB activation that is induced by VIIa and abrogated the enhanced proliferation, migration, and survival of SW620 cells by VIIa treatment. Both safingol and PDTC (NF-κB inhibitor) could apparently rescue the effects of VIIa on expression of MMP-9, caspase-3, TF, and Bcl-2/bax in SW620 cells. Collectively, the data in this study suggest that TF/VIIa/PAR2-induced SW620 cell proliferation, migration, and survival are ascribed to the activation of PKCα, and these effects are achieved through PKCα downstream signaling pathways, ERK1/2 and NF-κB.     

α-Catenin inhibits glioma cell migration,invasion, and proliferation by suppression of β-catenin transactivation

Patients with glioblastomas, the most common primary tumors of the central nervous system, have poor prognoses because of uncontrolled tumor cell invasion and proliferation. β-Catenin plays an important role in tumor development. However, whether α-catenin expression contributes to β-catenin transactivation in glioma cells is largely unknown. We report here that α-catenin expression abrogates epidermal growth factor receptor (EGFR)-activation-induced β-catenin nuclear translocation in human glioblastoma cells, thereby attenuating β-catenin transactivation and the expression of its downstream genes CCND1 and c-myc. In addition, ectopic expression of α-catenin or depletion of β-catenin suppresses EGF-promoted glioblastoma cell migration, invasion, and proliferation. In contrast, α-catenin depletion promotes β-catenin nuclear translocation and transactivation, and tumor cell motility and growth. These findings reveal the importance of β-catenin regulation by α-catenin in cellular activities of glioblastoma cells.     

PTHrP promotes colon cancer cell migration and invasion in an integrin α6β4-dependent manner through activation of Rac1

Parathyroid hormone-related protein (PTHrP) is expressed by human colon cancer tissue and cell lines. Rac1 GTPase enhances colon cancer cell migration and invasion. Here we report a positive correlation between PTHrP expression and Rac1 activity in LoVo (human colon cancer) cells. The positive effects of PTHrP on Rac1 activity and on cell migration and invasion are mediated via the guanine nucleotide exchange factor Tiam1. Knockdown of integrin α6β4, which is upregulated by PTHrP, negates the PTHrP-mediated increase in Rac1 activation. Integrin α6β4 signals synergistically with growth factor receptors to activate the phosphatidylinositol 3-kinase (PI3-K) pathway. Chemical inhibition of PI3-K negates the PTHrP-mediated effects on Tiam1 and Rac1 activity. Tumors from PTHrP-overexpressing LoVo cells also show increased expression of Tiam1. Taken together, these observations provide evidence of a link between PTHrP and Rac1 activity through integrin α6β4, resulting in enhanced cell migration and invasion. Targeting PTHrP production in colon cancer may thus prove therapeutically beneficial.     

Cooperation of protease-activated receptor 1 and integrin ανβ5 in thrombin-mediated lung cancer cell invasion

Protease-activated receptor 1 (PAR1) and integrins play an important role in thrombin-mediated tumor cell invasion. However, the role of PAR1 and integrin ανβ5 and the relationship between the two receptors in thrombin-induced lung cancer invasion remains unknown. Moreover, the mechanisms through which immobilized thrombin facilitates tumor invasion are poorly understood. In this study, both native and immobilized thrombin promoted lung cancer cell adhesion, migration and extracellular signal-regulated kinase phosphorylation. Integrin ανβ5 is involved in both native and immobilized thrombin-mediated tumor cell invasion; PAR1 had no effect on immobilized thrombin-mediated cell invasion. PAR1 and integrin ανβ5 colocalized on the surface of native thrombin-treated cells. This study suggests that targeting of integrin ανβ5 or the PAR1-integrin ανβ5 complex may present an important therapeutic opportunity to prevent lung cancer invasion.