Vitronectin–αvβ3 Integrin Engagement Directs Hypoxia-Resistant mTOR Activity and Sustained Protein Synthesis Linked to Invasion by Breast Cancer Cells

Focal adhesion-derived liquid-liquid phase separations regulate mRNA translation

Liquid-liquid phase separation (LLPS) has emerged as a major organizing principle in cells. Recent work showed that multiple components of integrin-mediated focal adhesions including p130Cas can form LLPS, which govern adhesion dynamics and related cell behaviors. In this study, we found that the focal adhesion protein p130Cas drives formation of structures with the characteristics of LLPS that bud from focal adhesions into the cytoplasm. Condensing concentrated cytoplasm around p130Cas-coated beads allowed their isolation, which were enriched in a subset of focal adhesion proteins, mRNAs and RNA binding proteins, including those implicated in inhibiting mRNA translation. Plating cells on very high concentrations of fibronectin to induce large focal adhesions inhibited message translation which required p130Cas and correlated with droplet formation. Photo-induction of p130Cas condensates using the Cry2 system also reduced translation. These results identify a novel regulatory mechanism in which high adhesion limits message translation via induction of p130Cas-dependent cytoplasmic LLPS. This mechanism may contribute to the quiescent state of very strongly adhesive myofibroblasts and senescent cells.

Interleukin-1β and plasminogen activating system members in endometriotic stromal cell migration/invasion

OBJECTIVE

To study the role of interleukin (IL)-1β and the plasminogen activating (PA) system members in endometriotic stromal cell (ESC) migration/invasion.

DESIGN

Primary cultures of ESCs.

SETTING

Tertiary referral center for endometriosis and pelvic pain.

PATIENT(S)

Patients with surgically excised endometriosis.

INTERVENTION(S)

Interleukin-1β stimulation of primary cultures of ESCs and knockdown of the PA system members urokinase plasminogen activator (uPA), uPA receptor, and plasminogen activator inhibitor-1 (PAI-1).

MAIN OUTCOME MEASURE(S)

Invasion/migration assays.

RESULT(S)

In primary cultures, IL-1β-stimulated ESC production of the PA system members uPA, uPA receptor, and PAI-1. Interleukin-1β also enhanced ESC migration and invasion, and these effects were inhibited by the IL-1 receptor-1 antagonist anakinra. Knockdown of each of the 3 PA system members also inhibited ESC migration and invasion. Knockdown of these PA system members further attenuated the impact of IL-1β on migration and invasion, suggesting that they mediated the promigration and proinvasion effects of IL-1β. To supplement the cell culture work, immunohistochemistry was performed on tissue sections of endometriotic epithelium/stroma: uPA, PAI-1, and IL-1β histoscores were not found to be correlated with each other.

CONCLUSION(S)

In primary cultures of ESCs, IL-1β induces migration and invasion, which is mediated by PA system members and inhibited by the drug anakinra. However, the immunohistochemistry expression of IL-1β, urokinase plasminogen inhibitor-1, and PAI-1 were not correlated, suggesting other regulatory mechanisms for PA system members. Inhibition of IL-1β (e.g., with anakinra) may have potential as a novel treatment approach for the migration/invasion of endometriosis.

Functional cRGD-Conjugated Polymer Prodrug for Targeted Drug Delivery to Liver Cancer Cells

To overcome the limitation of conventional nanodrugs in tumor targeting efficiency, coupling targeting ligands to polymeric nanoparticles can enhance the specific binding of nanodrugs to tumors. Cyclo(Arg-Gly-Asp-d-Phe-Lys) (abbreviated as c(RGDfK)) peptide has been widely adopted due to its high affinity to the tumor marker α_vβ₃ integrin receptor. In this study, we develop a cRGD peptide-conjugated camptothecin (CPT) prodrug, which enables self-assembly of nanoparticles for precise targeting and enrichment in tumor tissue. We first synthesized a camptothecin derivative (CPT-ss-N₃) with a reduction-sensitive bond and simultaneously modified PEG to obtain cRGD-PEG-N₃. After ring-opening polymerization of the 2-(but-3-yn-1-yolxy)-2-oxo-1,3,2-dioxaphospholane (BYP), an amphiphilic polymeric prodrug, referred to as cRGD-PEG-g-(PBYP-ss-CPT), was obtained via copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. The self-assembly in buffer solution of the cRGD-functional prodrug was studied through DLS and TEM. The in vitro drug release behavior of cRGD-PEG-g-(PBYP-ss-CPT) nanoparticles was investigated. The results show that the nanoparticles are reduction-responsive and the bonded CPT can be released. Endocytosis and MTT assays demonstrate that the cRGD-conjugated prodrug has better affinity for tumor cells, accumulates more intracellularly, and is therefore, more effective. The in vivo drug metabolism studies show that nanoparticles greatly prolong the retention time in circulation. By monitoring drug distribution in tumor and in various tissues, we find that free CPT can be rapidly metabolized, resulting in low accumulation in all tissues. However, cRGD-PEG-g-(PBYP-ss-CPT) nanoparticles accumulate in tumor tissues in higher amounts than PEG-g-(PBYP-ss-CPT) nanoparticles, except for the inevitable capture by the liver. This indicates that the nanomedicine with cRGD has a certain targeting property, which can improve drug delivery efficiency.

Nondegradable Collagen Increases Liver Fibrosis but Not Hepatocellular Carcinoma in Mice

Although hepatocellular cancer (HCC) usually occurs in the setting of liver fibrosis, the causal relationship between liver fibrosis and HCC is unclear. in vivo and in vitro models of HCC involving Colr/r mice (that produce a collagenase-resistant type I collagen) or wild-type (WT) mice were used to assess the relationship between type I collagen, liver fibrosis, and experimental HCC. HCC was either chemically induced in WT and Colr/r mice or Hepa 1-6 cells were engrafted into WT and Colr/r livers. The effect of hepatic stellate cells (HSCs) from WT and Colr/r mice on the growth of Hepa 1-6 cells was studied by using multicellular tumor spheroids and xenografts. Collagen type I deposition and fibrosis were increased in Colr/r mice, but they developed fewer and smaller tumors. Hepa 1-6 cells had reduced tumor growth in the livers of Colr/r mice. Although Colr/r HSCs exhibited a more activated phenotype, Hepa 1-6 growth and malignancy were suppressed in multicellular tumor spheroids and in xenografts containing Colr/r HSCs. Treatment with vitronectin, which mimics the presence of degraded collagen fragments, converted the Colr/r phenotype into a WT phenotype. Although Colr/r mice have increased liver fibrosis, they exhibited decreased HCC in several models. Thus, increased liver type I collagen does not produce increased experimental HCC.

Over-expression of vitronectin correlates with impaired survival in gastric cancers

Over-expression of vitronectin (VN) is associated with tumorigenesis. The present study aimed to evaluate the prognostic value of VN expression in gastric cancer.The least absolute shrinkage and selection operator analysis was performed to screen the hub gene from The Cancer Genome Atlas gastric cancer patients with complete follow-up data, and 347 patients were finally included. Moreover, 102 patients were enrolled from the Affiliated Fuzhou First Hospital of Fujian Medical University. VN expression in paired gastric cancer and adjacent gastric normal tissues was detected using immunohistochemistry, and the clinicopathological significance of VN expression was evaluated. The prognostic significance of VN expression in gastric cancer patients was evaluated using by Kaplan-Meier method and Cox regression analysis and confirmed using Oncomine.VN was the prognosis relative gene which screened by The Cancer Genome Atlas dataset. Moreover, we identified the VN expression in an external dataset by immunohistochemistry. The result demonstrated that VN expression was remarkedly elevated in gastric cancer tissues (P < .001). High VN expression correlated with higher pathological Tumor-Node-Metastasis stage, and poorer survival outcomes. Cox regression analysis showed that VN expression was independently predictive of overall survival (OS) and disease-free survival (P = .004, P < .001, respectively). A prognostic risk score for OS was built based on VN expression. A meta-analysis from Oncomine datasets revealed that significantly lower VN mRNA levels in gastric cancer correlated with poorer OS.VN expression could be a prognostic marker of gastric cancer.

Targeted Therapy to β3 Integrin Reduces Chemoresistance in Breast Cancer Bone Metastases

Breast cancer bone metastases are common and incurable. Tumoral integrin β3 (β3) expression is induced through interaction with the bone microenvironment. Although β3 is known to promote bone colonization, its functional role during therapy of established bone metastases is not known. We found increased numbers of β3+ tumor cells in murine bone metastases after docetaxel chemotherapy. β3+ tumor cells were present in 97% of post-neoadjuvant chemotherapy triple-negative breast cancer patient samples (n = 38). High tumoral β3 expression was associated with worse outcomes in both pre- and postchemotherapy triple-negative breast cancer groups. Genetic deletion of tumoral β3 had minimal effect in vitro, but significantly enhanced in vivo docetaxel activity, particularly in the bone. Rescue experiments confirmed that this effect required intact β3 signaling. Ultrastructural, transcriptomic, and functional analyses revealed an alternative metabolic response to chemotherapy in β3-expressing cells characterized by enhanced oxygen consumption, reactive oxygen species generation, and protein production. We identified mTORC1 as a candidate for therapeutic targeting of this β3-mediated, chemotherapy-induced metabolic response. mTORC1 inhibition in combination with docetaxel synergistically attenuated murine bone metastases. Furthermore, micelle nanoparticle delivery of mTORC1 inhibitor to cells expressing activated αvβ3 integrins enhanced docetaxel efficacy in bone metastases. Taken together, we show that β3 integrin induction by the bone microenvironment promotes resistance to chemotherapy through an altered metabolic response that can be defused by combination with αvβ3-targeted mTORC1 inhibitor nanotherapy. Our work demonstrates the importance of the metastatic microenvironment when designing treatments and presents new, bone-specific strategies for enhancing chemotherapeutic efficacy.

AKT in Bone Metastasis of Solid Tumors: A Comprehensive Review

Simple Summary

Bone metastasis is a frequent complication of solid tumors and leads to a reduced overall survival. Although much progress has been made in the field of tumor therapy in the last years, bone metastasis depicts a stage of the disease with a lack of appropriate therapeutical options. Hence, this review aims to present the role of AKT in bone metastasis of solid tumors to place the spotlight on AKT as a possible therapeutical approach for patients with bone metastases. Furthermore, we intended to discuss postulated underlying molecular mechanisms of the bone metastasis-promoting effect of AKT, especially in highly bone-metastatic breast, prostate, and lung cancer. To conclude, this review identified the AKT kinase as a potential therapeutical target in bone metastasis and revealed remaining questions, which need to be addressed in further research projects.

Abstract

Solid tumors, such as breast cancer and prostate cancer, often form bone metastases in the course of the disease. Patients with bone metastases frequently develop complications, such as pathological fractures or hypercalcemia and exhibit a reduced life expectancy. Thus, it is of vital importance to improve the treatment of bone metastases. A possible approach is to target signaling pathways, such as the PI3K/AKT pathway, which is frequently dysregulated in solid tumors. Therefore, we sought to review the role of the serine/threonine kinase AKT in bone metastasis. In general, activation of AKT signaling was shown to be associated with the formation of bone metastases from solid tumors. More precisely, AKT gets activated in tumor cells by a plethora of bone-derived growth factors and cytokines. Subsequently, AKT promotes the bone-metastatic capacities of tumor cells through distinct signaling pathways and secretion of bone cell-stimulating factors. Within the crosstalk between tumor and bone cells, also known as the vicious cycle, the stimulation of osteoblasts and osteoclasts also causes activation of AKT in these cells. As a consequence, bone metastasis is reduced after experimental inhibition of AKT. In summary, AKT signaling could be a promising therapeutical approach for patients with bone metastases of solid tumors.

A frog-derived bionic peptide with discriminative inhibition of tumors based on integrin αvβ3 identification

Aureins, natural active peptides extracted from skin secretions of Australian bell frogs, have become a research focus due to the antitumor effects caused by lysing cell membranes. However, clinical translation of Aureins is still limited by non-selective toxicity between normal and cancer cells. Herein, by structure-activity relationship analysis and rational linker design, a dual-function fusion peptide RA3 is designed by tactically fusing Aurein peptide A1 with strong anticancer activity, with a tri-peptide with integrin αvβ3-binding ability which was screened in our previous work. Rational design and selection of fusion linkers ensures α-helical conformation and active functions of this novel fusion peptide, inducing effective membrane rupture and selective apoptosis of cancer cells. The integrin binding and tumor recognition ability of the fusion peptide is further validated by fluorescence imaging in cell and mouse models, in comparison with the non-selective A1 peptide. Meanwhile, increased stability and superior therapeutic efficacy are achieved in vivo for the RA3 fusion peptide. Our study highlights that aided by computational simulation technologies, the biomimetic fusion RA3 peptide has been successfully designed, surmounting the poor tumor-selectivity of the natural defensive peptide, serving as a promising therapeutic agent for cancer treatment.

The Biological Functions and Clinical Applications of Integrins in Cancers

Integrins are the adhesion molecules and receptors of extracellular matrix (ECM). They mediate the interactions between cells-cells and cells-ECM. The crosstalk between cancer cells and their microenvironment triggers a variety of critical signaling cues and promotes the malignant phenotype of cancer. As a type of transmembrane protein, integrin-mediated cell adhesion is essential in regulating various biological functions of cancer cells. Recent evidence has shown that integrins present on tumor cells or tumor-associated stromal cells are involved in ECM remodeling, and as mechanotransducers sensing changes in the biophysical properties of the ECM, which contribute to cancer metastasis, stemness and drug resistance. In this review, we outline the mechanism of integrin-mediated effects on biological changes of cancers and highlight the current status of clinical treatments by targeting integrins.

A review on the role of M2 macrophages in bladder cancer; pathophysiology and targeting

Tumor-associated macrophages (TAMs) which are often referred to as immunosuppressive cells (M2 macrophage), constitute a subset of tumor microenvironment cells and affect tumor progression in solid tumors. Recently, these cells have gained remarkable importance as therapeutic candidates for solid tumors. In bladder cancer, major studies have focused on evaluating TAMs in response to Bacillus Calmette-Guerin (BCG) therapy. M2 macrophages may directly impact the BCG-induced immune responses against tumor in bladder cancer. They are the main inhibitors of the tumor microenvironment that promotes growth and metastasis of the tumor. However, the clinical significance of M2 macrophages in bladder cancer is controversial. In this review, we will discuss the clinical significance of M2 macrophages in prognosis of bladder cancer as well as worth of their potential targeting in bladder cancer treatment. In the following, we will introduce important factors resulting in M2 macrophage promotion and also experimental therapeutic agents that may cause the inhibition of bladder cancer tumor growth.

Eukaryotic initiation factor 4E-binding protein as an oncogene in breast cancer

BACKGROUND

Eukaryotic Initiation Factor 4E-Binding Protein (EIF4EBP1, 4EBP1) is overexpressed in many human cancers including breast cancer, yet the role of 4EBP1 in breast cancer remains understudied. Despite the known role of 4EBP1 as a negative regulator of cap-dependent protein translation, 4EBP1 is predicted to be an essential driving oncogene in many cancer cell lines in vitro, and can act as a driver of cancer cell proliferation. EIF4EBP1 is located within the 8p11-p12 genomic locus, which is frequently amplified in breast cancer and is known to predict poor prognosis and resistance to endocrine therapy.

METHODS

Here we evaluated the effect of 4EBP1 targeting using shRNA knock-down of expression of 4EBP1, as well as response to the mTORC targeted drug everolimus in cell lines representing different breast cancer subtypes, including breast cancer cells with the 8p11-p12 amplicon, to better define a context and mechanism for oncogenic 4EBP1.

RESULTS

Using a genome-scale shRNA screen on the SUM panel of breast cancer cell lines, we found 4EBP1 to be a strong hit in the 8p11 amplified SUM-44 cells, which have amplification and overexpression of 4EBP1. We then found that knock-down of 4EBP1 resulted in dramatic reductions in cell proliferation in 8p11 amplified breast cancer cells as well as in other luminal breast cancer cell lines, but had little or no effect on the proliferation of immortalized but non-tumorigenic human mammary epithelial cells. Kaplan-Meier analysis of EIF4EBP1 expression in breast cancer patients demonstrated that overexpression of this gene was associated with reduced relapse free patient survival across all breast tumor subtypes.

CONCLUSIONS

These results are consistent with an oncogenic role of 4EBP1 in luminal breast cancer and suggests a role for this protein in cell proliferation distinct from its more well-known role as a regulator of cap-dependent translation.

Myosin 1F Regulates M1-Polarization by Stimulating Intercellular Adhesion in Macrophages

Intestinal macrophages are highly mobile cells with extraordinary plasticity and actively contribute to cytokine-mediated epithelial cell damage. The mechanisms triggering macrophage polarization into a proinflammatory phenotype are unknown. Here, we report that during inflammation macrophages enhance its intercellular adhesion properties in order to acquire a M1-phenotype. Using in vitro and in vivo models we demonstrate that intercellular adhesion is mediated by integrin-αVβ3 and relies in the presence of the unconventional class I myosin 1F (Myo1F). Intercellular adhesion mediated by αVβ3 stimulates M1-like phenotype in macrophages through hyperactivation of STAT1 and STAT3 downstream of ILK/Akt/mTOR signaling. Inhibition of integrin-αVβ3, Akt/mTOR, or lack of Myo1F attenuated the commitment of macrophages into a pro-inflammatory phenotype. In a model of colitis, Myo1F deficiency strongly reduces the secretion of proinflammatory cytokines, decreases epithelial damage, ameliorates disease activity, and enhances tissue repair. Together our findings uncover an unknown role for Myo1F as part of the machinery that regulates intercellular adhesion and polarization in macrophages.

BPIFB1 (LPLUNC1) inhibits radioresistance in nasopharyngeal carcinoma by inhibiting VTN expression

Bactericidal/permeability-increasing-fold-containing family B member 1 (BPIFB1, previously named LPLUNC1) is highly expressed in the nasopharynx and significantly downregulated in nasopharyngeal carcinoma (NPC). Low expression is also associated with poor prognosis in patients with NPC. Radiotherapy is a routine treatment for NPC; however, radioresistance is a major cause of treatment failure. Thus, we aimed to investigate the role of BPIFB1 in the radioresponse of NPC. Colony formation and cell survival results showed that BPIFB1 sensitized NPC cells to ionizing radiation. VTN, a previously identified BPIFB1-binding protein, was shown to induce cell proliferation and survival, G2/M phase arrest, DNA repair, activation of the ATM-Chk2 and ATR-Chk1 pathways, and anti-apoptotic effects after exposure to radiation, facilitating NPC cell radioresistance. However, BPIFB1 inhibited this VTN-mediated radioresistance, ultimately improving NPC radiosensitivity. In conclusion, this study is the first to demonstrate the functions of BPIFB1 and VTN in the NPC radioresponse. Our findings indicated that promoting BPIFB1 expression and targeting VTN might represent new therapeutic strategies for NPC.

Hypoxia Enhances Fusion of Oral Squamous Carcinoma Cells and Epithelial Cells Partly via the Epithelial-Mesenchymal Transition of Epithelial Cells

Increasing evidence and indications showed that cell fusion is crucial in tumor development and metastasis, and hypoxia, a closely linked factor to tumor microenvironment, which can lead to EMT, induces angiogenesis and metastasis in tumor growth. However, the relationship between hypoxia and fusion has not been reported yet. EMT will change some proteins in the epithelial cell surface and the changes of proteins in cell surface may increase cell fusion. This study found that hypoxia promotes the spontaneous cell fusion between Oral Squamous Carcinoma Cells (OSCCs) and Human Immortalized Oral Epithelial Cells (HIOECs). At the same time, Hypoxia can lead to EMT, and hypoxia-pretreated HIOECs increased fusion rate with OSCC, while the fusion rate was significantly reduced by DAPT, a kind of EMT blocker. Therefore, epithelial cells can increase spontaneously cell fusion with OSCC by EMT. Our study may provide a new insight to link among tumor microenvironment, cell fusion, and cancer.

Integrin-uPAR signaling leads to FRA-1 phosphorylation and enhanced breast cancer invasion

Background

The Fos-related antigen 1 (FRA-1) transcription factor promotes tumor cell growth, invasion and metastasis. Phosphorylation of FRA-1 increases protein stability and function. We identify a novel signaling axis that leads to increased phosphorylation of FRA-1, increased extracellular matrix (ECM)-induced breast cancer cell invasion and is prognostic of poor outcome in patients with breast cancer.

Methods

While characterizing five breast cancer cell lines derived from primary human breast tumors, we identified BRC-31 as a novel basal-like cell model that expresses elevated FRA-1 levels. We interrogated the functional contribution of FRA-1 and an upstream signaling axis in breast cancer cell invasion. We extended this analysis to determine the prognostic significance of this signaling axis in samples derived from patients with breast cancer.

Results

BRC-31 cells display elevated focal adhesion kinase (FAK), SRC and extracellular signal-regulated (ERK2) phosphorylation relative to luminal breast cancer models. Inhibition of this signaling axis, with pharmacological inhibitors, reduces the phosphorylation and stabilization of FRA-1. Elevated integrin α_Vβ₃ and uPAR expression in these cells suggested that integrin receptors might activate this FAK-SRC-ERK2 signaling. Transient knockdown of urokinase/plasminogen activator urokinase receptor (uPAR) in basal-like breast cancer cells grown on vitronectin reduces FRA-1 phosphorylation and stabilization; and uPAR and FRA-1 are required for vitronectin-induced cell invasion. In clinical samples, a molecular component signature consisting of vitronectin-uPAR-uPA-FRA-1 predicts poor overall survival in patients with breast cancer and correlates with an FRA-1 transcriptional signature.

Conclusions

We have identified a novel signaling axis that leads to phosphorylation and enhanced activity of FRA-1, a transcription factor that is emerging as an important modulator of breast cancer progression and metastasis.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-0936-8) contains supplementary material, which is available to authorized users.

Fibrotic microenvironment promotes the metastatic seeding of tumor cells via activating the fibronectin 1/secreted phosphoprotein 1-integrin signaling

The seeding of tumor cells is a critical step in the process of metastasis, but whether and how the microenvironment of target organs affects metastatic seeding remain largely unknown. Based on cell and mouse models, we found that the metastatic seeding and outgrowth of tumor cells were significantly enhanced in fibrotic lungs. The conditioned medium from both fibrotic lungs and the fibrotic lung-derived fibroblasts (CM-FLF) had a strong activity to chemoattract tumor cells and to inhibit the apoptosis of tumor cells. Subsequent investigations revealed that the levels of fibronectin 1 (FN1) and secreted phosphoprotein 1 (SPP1) were significantly increased in fibrotic lungs. Silencing of FN1 in the fibrotic lung-derived fibroblasts dramatically decreased the chemoattracting activity of CM-FLF, while silencing of FN1 or SPP1 in fibroblasts attenuated the anti-apoptosis activity of CM-FLF. Moreover, the CM-FLF-induced apoptosis resistance or chemotaxis of tumor cells was attenuated when ITGAV, the common receptor of FN1 and SPP1, was silenced by RNA interference or blocked by GRGDS treatment in tumor cells. Consistently, ITGAV silencing or GRGDS treatment significantly inhibited the seeding and outgrowth of tumor cells in fibrotic lungs in vivo. Collectively, we suggest that fibrotic microenvironment may enhance the metastatic seeding of tumor cells in the lung by chemoattracting tumor cells and inhibiting their apoptosis via activating the FN1/SPP1-ITGAV signaling. These findings give a novel insight into the regulatory mechanisms of cancer metastasis and provide a potential target for anti-metastasis therapy.

One-Step Synthesis of Targeted Acid-Labile Polysaccharide Prodrug for Efficiently Intracellular Drug Delivery

The therapeutic potential of the active targeting and acid-sensitive polysaccharide prodrug was investigated. The active targeting of polysaccharide prodrug was based on the specific interaction between cyclo(Arg-Gly-Asp-d-Phe-Lys) peptide (c(RGDfK)) and its receptor α_vβ₃ integrin overexpressed on the membrane of tumor cells. The cRGD-modified doxorubicin-conjugated hydroxyethyl starch (HES=DOX/cRGD) was synthesized via a one-step Schiff base reaction between oxidized HES, and DOX and c(RGDfK) that achieved an acid-accelerated drug release profile. The targeted polysaccharide prodrug self-assembled into micelle in aqueous environment with a moderate hydrodynamic diameter of 77.1 nm. All data in vitro indicated enhanced cell uptake and elevated cytotoxicity of HES=DOX/cRGD toward human malignant melanoma A375 cells compared with HES=DOX and DOX. Moreover, the smart prodrug also exhibited upregulated accumulation in the tumor, improved antitumor efficacy, and reduced systemic cytotoxicity in vivo. The cRGD-decorated acid-sensitive polysaccharide prodrug was advantageous in both antitumor efficacy and systemic security, showing great prospect in clinical application.

BPIFB1 (LPLUNC1) inhibits migration and invasion of nasopharyngeal carcinoma by interacting with VTN and VIM

Background:

Bactericidal/Permeability-increasing-fold-containing family B member 1 (BPIFB1, previously termed LPLUNC1) is highly expressed in the nasopharynx, significantly downregulated in nasopharyngeal carcinoma (NPC), and associated with prognosis in NPC patients. Because metastasis represents the primary cause of NPC-related death, we explored the role of BPIFB1 in NPC migration and invasion.

Methods:

The role of BPIFB1 in NPC metastasis was investigated in vitro and in vivo. A co-immunoprecipitation assay coupled with mass spectrometry was used to identify BPIFB1-binding proteins. Additionally, western blotting, immunofluorescence, and immunohistochemistry allowed assessment of the molecular mechanisms associated with BPIFB1-specific metastatic inhibition via vitronectin (VTN) and vimentin (VIM) interactions.

Results:

Our results showed that BPIFB1 expression markedly inhibited NPC cell migration, invasion, and lung-metastatic abilities. Additionally, identification of two BPIFB1-interacting proteins, VTN and VIM, showed that BPIFB1 reduced VTN expression and the formation of a VTN-integrin αV complex in NPC cells, leading to inhibition of the FAK/Src/ERK signalling pathway. Moreover, BPIFB1 attenuated NPC cell migration and invasion by inhibiting VTN- or VIM-induced epithelial–mesenchymal transition.

Conclusions:

This study represents the first demonstration of BPIFB1 function in NPC migration, invasion, and lung metastasis. Our findings indicate that re-expression of BPIFB1 might represent a useful strategy for preventing and treating NPC.

Probing Cell Adhesion Profiles with a Microscale Adhesive Choice Assay

In this work, we introduce, to our knowledge, a new set of adhesion-based biomarkers for characterizing mammalian cells. Mammalian cell adhesion to the extracellular matrix influences numerous physiological processes. Current in vitro methods to probe adhesion focus on adhesive force to a single surface, which can investigate only a subcomponent of the adhesive, motility, and polarization cues responsible for adhesion in the 3D tissue environment. Here, we demonstrate a method to quantify the transhesive properties of cells that relies on the microscale juxtaposition of two extracellular matrix-coated surfaces. By multiplexing this approach, we investigate the unique transhesive profiles for breast cancer cells that are adapted to colonize different metastatic sites. We find that malignant breast cancer cells readily transfer to new collagen I surfaces, and away from basement membrane proteins. Integrins and actin polymerization largely regulate this transfer. This tool can be readily adopted in cell biology and cancer research to uncover, to our knowledge, novel drivers of adhesion (or de-adhesion) and sort cell populations based on complex phenotypes with physiological relevance.

Decreasing Eukaryotic Initiation Factor 3C (EIF3C) Suppresses Proliferation and Stimulates Apoptosis in Breast Cancer Cell Lines Through Mammalian Target of Rapamycin (mTOR) Pathway

Background

Translation initiation is the rate limiting step of protein synthesis and is highly regulated. Eukaryotic initiation factor 3C (EIF3C), an oncogene overexpressed in several human cancers, plays an important role in tumorigenesis and cell proliferation.

Material/Methods

Immunohistochemistry was used to determine the expression of EIF3C in breast cancer tissues from 42 patients. We investigated whether EIF3C silencing decreases breast cancer cell proliferation as assessed by colony formation assay, and whether EIF3C gene knockdown induces apoptosis as assessed by flow cytometry analysis. We utilized the stress and apoptosis signaling antibody array kit, while p-ERK1/2, p-Akt, p-Smad2, p-p38 MAPK, cleaved caspase-3, and cleaved caspase-7 were explored between EIF3C-siRNA and controls. Furthermore, the effects of EIF3C gene knockdown in mTOR pathway were analyzed by western blotting for different cell lines.

Results

In EIF3C-positive tumors, 32 out of 42 showed significantly higher frequencies of high grade group by immunoreactivity (p=0.0016). BrdU incorporation after four days of cell plating was significantly suppressed in MDA-MB-231 cells by EIF3C knockdown compared with controls, with average changes of 7.8-fold (p<0.01). Clone number was significantly suppressed in MDA-MB-231 cells by EIF3C knockdown compared with controls (p<0.05). Cell apoptosis was significantly increased in the EIF3C-siRNA group when compared with the cells that were transfected with scrambled siRNA (3.51±0.0842 versus 13.24±0.2307, p<0.01). The mTOR signaling pathway was involved in decreasing EIF3C translational efficiency.

Conclusions

Unveiling the mechanisms of EIF3 action in tumorigenesis may help identify attractive targets for cancer therapy.

Assessment of Vitronectin, Soluble Epithelial-Cadherin and TGF-β1 as a Serum Biomarker with Predictive Value for Endometrial and Ovarian Cancers

Objectives

Extracellular matrix components, including vitronectin (VN), soluble epithelial-cadherin (sE-cadherin) and transforming growth factor-beta 1 (TGF-β1), play a key role in the invasion and metastasis of cancer. The objective of the study was to determine the clinical significance of serum levels of these molecules in patients with endometrial and ovarian cancers.

Materials and Methods

Serum levels of VN, sE-cadherin and TGF-β1 in patients with endometrial (n=28) and ovarian cancers (n=40) and healthy controls (n=41) were measured by ELISA using commercial kits.

Results

A significant difference was found in VN, sE-cadherin and TGF-β1 levels between patients and healthy controls (p<0.01, p<0.01 and p<0.05, respectively). Serum VN and sE-cadherin levels were decreased significantly in both endometrial and ovarian cancer patients compared to controls (p<0.01, p<0.01, respectively). Conversely, TGF-β1 levels were increased significantly in patients with ovarian cancer as compared to controls (p<0.01). There was no significant difference between healthy controls and endometrial cancer patients.

Conclusion

In conclusion, our study reveals that serum VN, sE-cadherin and TGF-β1 levels can be candidate targets for providing new diagnostic procedures in endometrial and ovarian cancers.

Translational control and the cancer cell response to stress

The evidence for the importance of aberrant translation in cancer cells is overwhelming. Reflecting the wealth of data, there are excellent reviews delineating how ribosomes and initiation factors are linked to cancer [1-3], and the therapeutic strategies being devised to target them [4]. Changes in translational efficiency can engender a malignant phenotype without the need for chromatin reorganization, transcription, splicing and mRNA export [5,6]. Thus, cancer-related modulations of the translational machinery are ideally suited to allow cancer cells to respond to the various stresses encountered along the path of tumorigenesis and organism-wide dissemination [7^•,8,9,10^•]. Emerging findings supporting this notion are the focus of this review.

Tumor microenvironment-mediated chemoresistance in breast cancer

Therapy resistance or tumor relapse in cancer is common. Tumors develop resistance to chemotherapeutic through a variety of mechanisms, with tumor microenvironment (TM) serving pivotal roles. Using breast cancer as a paradigm, we propose that responses of cancer cells to drugs are not exclusively determined by their intrinsic characteristics but are also controlled by deriving signals from TM. Affected microenvironment by chemotherapy is an avenue to promote phenotype which tends to resist on to be ruined. Therefore, exclusively targeting cancer cells does not demolish tumor recurrence after chemotherapy. Regardless of tumor-microenvironment pathways and their profound influence on the responsiveness of treatment, diversity of molecular properties of breast cancer also behave differently in terms of response to chemotherapy. And also it is assumed that there is cross-talk between phenotypic diversity and TM. Collectively, raising complex signal from TM in chemotherapy condition often encourages cancer cells are not killed but strengthen. Here, we summarized how TM modifies responses to chemotherapy in breast cancer. We also discussed successful treatment strategies have been considered TM in breast cancer treatment.

New frontiers in translational control of the cancer genome

The past several years have seen dramatic leaps in our understanding of how gene expression is rewired at the translation level during tumorigenesis to support the transformed phenotype. This work has been driven by an explosion in technological advances and is revealing previously unimagined regulatory mechanisms that dictate functional expression of the cancer genome. In this Review we discuss emerging trends and exciting new discoveries that reveal how this translational circuitry contributes to specific aspects of tumorigenesis and cancer cell function, with a particular focus on recent insights into the role of translational control in the adaptive response to oncogenic stress conditions.

Matrix Gla protein repression by miR-155 promotes oncogenic signals in breast cancer MCF-7 cells

MGP is a protein that was initially associated with the inhibition of calcification in skeleton, soft tissues, and arteries, but more recently also implicated in cancer. In breast cancer, higher levels of MGP mRNA were associated with poor prognosis, but since this deregulation was never demonstrated at the protein level, we postulated the involvement of a post-transcriptional regulatory mechanism. In this work we show that MGP is significantly repressed by miR-155 in breast cancer MCF-7 cells, and concomitantly there is a stimulation of cell proliferation and cell invasiveness. This study brings new insights into the putative involvement of MGP and oncomiR-155 in breast cancer, and may contribute to develop new therapeutic strategies.

Fibronectin Deposition Participates in Extracellular Matrix Assembly and Vascular Morphogenesis

The extracellular matrix (ECM) has been demonstrated to facilitate angiogenesis. In particular, fibronectin has been documented to activate endothelial cells, resulting in their transition from a quiescent state to an active state in which the cells exhibit enhanced migration and proliferation. The goal of this study is to examine the role of polymerized fibronectin during vascular tubulogenesis using a 3 dimensional (3D) cell-derived de-cellularized matrix. A fibronectin-rich 3D de-cellularized ECM was used as a scaffold to study vascular morphogenesis of endothelial cells (ECs). Confocal analyses of several matrix proteins reveal high intra- and extra-cellular deposition of fibronectin in formed vascular structures. Using a small peptide inhibitor of fibronectin polymerization, we demonstrate that inhibition of fibronectin fibrillogenesis in ECs cultured atop de-cellularized ECM resulted in decreased vascular morphogenesis. Further, immunofluorescence and ultrastructural analyses reveal decreased expression of stromal matrix proteins in the absence of polymerized fibronectin with high co-localization of matrix proteins found in association with polymerized fibronectin. Evaluating vascular kinetics, live cell imaging showed that migration, migration velocity, and mean square displacement, are disrupted in structures grown in the absence of polymerized fibronectin. Additionally, vascular organization failed to occur in the absence of a polymerized fibronectin matrix. Consistent with these observations, we tested vascular morphogenesis following the disruption of EC adhesion to polymerized fibronectin, demonstrating that block of integrins α₅β₁ and α_vβ_3, abrogated vascular morphogenesis. Overall, fibronectin deposition in a 3D cell-derived de-cellularized ECM appears to be imperative for matrix assembly and vascular morphogenesis.

Vitronectin: a promising breast cancer serum biomarker for early diagnosis of breast cancer in patients

Breast cancer is the most common cancer in women worldwide, identification of new biomarkers for early diagnosis and detection will improve the clinical outcome of breast cancer patients. In the present study, we determined serum levels of vitronectin (VN) in 93 breast cancer patients, 30 benign breast lesions, 9 precancerous lesions, and 30 healthy individuals by enzyme-linked immunosorbent assays. Serum VN level was significantly higher in patients with stage 0-I primary breast cancer than in healthy individuals, patients with benign breast lesion or precancerous lesions, as well as those with breast cancer of higher stages. Serum VN level was significantly and negatively correlated with tumor size, lymph node status, and clinical stage (p < 0.05 in all cases). In addition, VN displayed higher area under curve (AUC) value (0.73, 95 % confidence interval (CI) [0.62-0.84]) than carcinoembryonic antigen (CEA) (0.64, 95 % CI [0.52-0.77]) and cancer antigen 15-3 (CA 15-3) (0.69, 95 % CI [0.58-0.81]) when used to distinguish stage 0-I cancer and normal control. Importantly, the combined use of three biomarkers yielded an improvement in receiver operating characteristic curve with an AUC of 0.83, 95 % CI [0.74-0.92]. Taken together, our current study showed for the first time that serum VN is a promising biomarker for early diagnosis of breast cancer when combined with CEA and CA15-3.

Microenvironment, tumor cell plasticity, and cancer

PURPOSE OF REVIEW

Much effort has been devoted to determining how cellular and noncellular components of the tumoral niche initiate and promote cancer development. Cancer cells perceive biochemical signals from components of the extracellular matrix (ECM) and sense physical features, such as matrix stiffness and cell confinement. The past decade has seen a better understanding of the biophysics and mechanobiology associated with cancer cells. Indeed, loss of mechanisms controlling the production, the degradation, and the remodeling of ECM contributes to tumor growth or cell dissemination by affecting cell contractility in response to ECM stiffness and by stimulating mechanical dependence of growth factor activation.

RESULTS

Cell plasticity allows adaptative strategies for cancer cells to survive or eventually escape from tumoral environment through modification of the microenvironment-cell interface, internal tension increase, and nuclear deformation partly leading to intratumoral heterogeneity. However, although alteration of the biomechanical properties of the ECM are sufficient to promote cell migration and invasion in cancer cells, this microenvironment can also provide a hospitable niche for tumor dormancy and resistance to cancer therapy.

CONCLUSION

The review will focus on how physicochemical properties of ECM might promote tumor growth or cell dissemination or on the contrary maintain quiescent state of cancer cells. It is crucial to clarify the molecular basis of mechanotransduction in the development and progression of tumors to identify new potential biomarkers and anticancer therapeutic targets.

Macrophages are recruited to hypoxic tumor areas and acquire a pro-angiogenic M2-polarized phenotype via hypoxic cancer cell derived cytokines Oncostatin M and Eotaxin

TAMs, a unique and distinct M2-skewed myeloid population of tumor stroma, exhibiting pro-tumor functions is fast emerging as a potential target for anti-cancer immunotherapy. Macrophage-recruitment and M2-polarization represent key TAMs-related phenomenon that are amenable to therapeutic intervention. However successful translation of these approaches into effective therapeutic regimen requires better characterization of tumor-microenvironment derived signals that regulate macrophage recruitment and their polarization. Owing to hypoxic milieu being a persistent feature of tumor-microenvironment and a major contributor to malignancy and treatment resistance, the current study was planned with an aim to decipher tumor cell responses to hypoxia vis-a-vis macrophage homing and phenotype switching. Here, we show that hypoxia-primed cancer cells chemoattract and polarize macrophages to pro-angiogenic M2-polarized subtype via Eotaxin and Oncostatin M. Concordantly, hypoxic regions of human breast-cancer specimen exhibited elevated Eotaxin and Oncostatin M levels with concurrently elevated M2-macrophage content. Blockade of Eotaxin/Oncostatin M not only prevented hypoxic breast-cancer cells from recruiting and polarizing macrophages towards an M2-polarized phenotype and retarded tumor progression in 4T1/BALB/c-syngenic-mice-model of breast-cancer but also enhanced the efficacy of anti-angiogenic Bevacizumab. The findings established these two cytokines as novel targets for devising effective anticancer therapy particularly for tumors that are refractory or develop resistance to anti-angiogenic therapeutics.

Mitotic quiescence, but not unique "stemness," marks the phenotype of bone metastasis-initiating cells in prostate cancer

This study aimed to identify subpopulations of prostate cancer cells that are responsible for the initiation of bone metastases. Using rapidly dividing human prostate cancer cell lines, we identified mitotically quiescent subpopulations (<1%), which we compared with the rapidly dividing populations for patterns of gene expression and for their ability to migrate to the skeletons of athymic mice. The study used 2-photon microscopy to map the presence/distribution of fluorescently labeled, quiescent cells and luciferase expression to determine the presence of growing bone metastases. We showed that the mitotically quiescent cells were very significantly more tumorigenic in forming bone metastases than fast-growing cells (55 vs. 15%) and had a unique gene expression profile. The quiescent cells were not uniquely stem cell like, with no expression of CD133 but had the same level expression of other putative prostate stem cell markers (CD44 and integrins α2/β1), when compared to the rapidly proliferating population. In addition, mitotic quiescence was associated with very high levels of C-X-C chemokine receptor type 4 (CXCR4) production. Inhibition of CXCR4 activity altered the homing of quiescent tumor cells to bone. Our studies suggest that mitotic dormancy is a unique phenotype that facilitates tumor cell colonization of the skeleton in prostate cancer.

Cancer and embryo expression protein 65 promotes cancer cell growth and metastasis

Cancer and embryo expression protein 65 (CEP65) is a centrosomal protein that is expressed at relatively high levels in embryonic tissue and different cancerous tissues, but its role in tumorigenesis remains unknown. In the present study, CEP65 was stably expressed in AGS gastric cancer cells. CEP65 was found to promote cell growth in the MTT assay and to enhance cell migration and invasion in Transwell chamber assays. To validate results from the in vitro experiments, CEP65 was stably expressed in BICR-H1 breast cancer cells through adenovirus-mediated transduction. By inoculating BICR-H1 cells on chick chorioallantoic membrane (CAM), it was found that CEP65 promotes cell growth on the CAM and increases cell metastasis to the lungs of the chicken. By utilizing a xenograft severe combined immunodeficiency mouse model, CEP65 was also found to accelerate BICR-H1 cell growth and metastasis to the lungs. Furthermore, it was shown that CEP65 increases matrix metalloproteinase (MMP)2 activity in zymographic assays, however, microarray screening and reverse transcription polymerase chain reaction validation revealed that CEP65 had no effect on the expression levels of MMP2 or MMP9, but decreased the expression levels of metastasis-associated genes, TIMP2, RAP and VTN. Taken together, the results of the present study demonstrated the oncogenic function of CEP65 in promoting cancer cell growth and metastasis.

Fibronectin promotes cell proliferation and invasion through mTOR signaling pathway activation in gallbladder cancer

Fibronectin (FN), a heterodimeric glycoprotein overexpressed in several types of tumors, has been implicated in cancer progression via the activation of integrin-mediated pro-oncogenic pathways. The FN level in human bile fluid is dramatically increased in malignant biliary diseases; however, FN expression and its biological functions in gallbladder cancer (GBC) remain unknown. In this study, we found that FN was overexpressed in GBC tissues and was associated with a worse prognosis in GBC patients. In vitro experimental studies indicated that exogenous FN significantly enhanced cell proliferation, invasion and active MMP-9 secretion in human GBC cell lines (GBC-SD and NOZ). Moreover, the key kinases of the mTOR signaling pathway, including FAK, Akt, mTOR and 4E-BP1, were markedly activated in a time-dependent manner in FN-treated GBC-SD and NOZ cells. The IHC statistical analyses validated that FN expression was positively correlated with the phosphorylation levels of the 4E-BP1 protein in GBC tissues. Furthermore, rapamycin, a specific inhibitor of mTOR, almost completely blocked FN-induced phosphorylation of 4E-BP1 and also partially abrogated the stimulatory effects of FN on GBC cell proliferation and invasion. In vivo, FN treatment significantly promoted the proliferation and metastasis of GBC cells and markedly activated Akt/mTOR/4E-BP1 signaling cascade. These findings demonstrate that FN may play a critical role in the modulation of cell proliferation and invasion via mTOR signaling pathway activation during GBC progression.

Gemcitabine resistance in breast cancer cells regulated by PI3K/AKT-mediated cellular proliferation exerts negative feedback via the MEK/MAPK and mTOR pathways

Chemoresistance is a major cause of cancer treatment failure and leads to a reduction in the survival rate of cancer patients. Phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) and mitogen-activated protein kinase (MAPK) pathways are aberrantly activated in many malignant tumors, including breast cancer, which may indicate an association with breast cancer chemoresistance. In this study, we generated a chemoresistant human breast cancer cell line, MDA-MB-231/gemcitabine (simplified hereafter as "231/Gem"), from MDA-MB-231 human breast cancer cells. Flow cytometry studies revealed that with the same treatment concentration of gemcitabine, 231/Gem cells displayed more robust resistance to gemcitabine, which was reflected by fewer apoptotic cells and enhanced percentage of S-phase cells. Through the use of inverted microscopy, Cell Counting Kit-8, and Transwell assays, we found that compared with parental 231 cells, 231/Gem cells displayed more morphologic projections, enhanced cell proliferative ability, and improved cell migration and invasion. Mechanistic studies revealed that the PI3K/AKT/mTOR and mitogen-activated protein kinase kinase (MEK)/MAPK signaling pathways were activated through elevated expression of phosphorylated (p)-extracellular signal-regulated kinase (ERK), p-AKT, mTOR, p-mTOR, p-P70S6K, and reduced expression of p-P38 and LC3-II (the marker of autophagy) in 231/Gem in comparison to control cells. However, there was no change in the expression of Cyclin D1 and p-adenosine monophosphate-activated protein kinase (AMPK). In culture, inhibitors of PI3K/AKT and mTOR, but not of MEK/MAPK, could reverse the enhanced proliferative ability of 231/Gem cells. Western blot analysis showed that treatment with a PI3K/AKT inhibitor decreased the expression levels of p-AKT, p-MEK, p-mTOR, and p-P70S6K; however, treatments with either MEK/MAPK or mTOR inhibitor significantly increased p-AKT expression. Thus, our data suggest that gemcitabine resistance in breast cancer cells is mainly mediated by activation of the PI3K/AKT signaling pathway. This occurs through elevated expression of p-AKT protein to promote cell proliferation and is negatively regulated by the MEK/MAPK and mTOR pathways.

Synthetic RGDS peptide attenuated lipopolysaccharide/D-galactosamine-induced fulminant hepatic failure in mice

BACKGROUND AND AIM

Fulminant hepatic failure (FHF) is a serious clinic syndrome with extremely poor prognosis and no effective treatment except for liver transplantation. Synthetic RGDS peptide, an inhibitor of integrins, was proved to suppress integrin signals. In this study, we investigated the protection effects of RGDS peptide on lipopolysaccharide/D-galactosamine (LPS/D-GalN)-induced FHF and the underlying molecular mechanisms.

METHODS

Synthetic RGDS peptide was given intraperitoneally 30 min before LPS/D-GalN injection. Liver function and the extent of liver injury were analyzed biochemically and pathologically respectively. Enzyme-linked immunosorbent assay, real-time polymerase chain reaction and Western blotting were used to detect effectors and signaling molecules.

RESULTS

Pretreatment with synthetic RGDS peptide significantly improved LPS/D-GalN-induced mortality, and liver injury as determined by alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, as well as pathological analysis. In addition, RGDS peptide significantly reduced tumor necrosis factor (TNF)-α and macrophage inflammatory protein (MIP)-2 production, and decreased myeloperoxidase (MPO) and NF-κB activity. Furthermore, Western blotting indicated that the levels of phospho-integrin β3, phospho-focal adhesion kinase (FAK) and phospho-p38 mitogen-activated protein kinases (MAPK) decreased with RGDS peptide pretreatment.

CONCLUSION

Together, these data suggest that synthetic RGDS peptide protect against LPS/D-GalN-induced FHF by inhibiting inflammatory cells migration and blocking the integrin αVβ3-FAK-p38 MAPK and NF-κB signaling.

Ampelopsin suppresses breast carcinogenesis by inhibiting the mTOR signalling pathway

The mammalian target of rapamycin (mTOR), which is a master regulator of cellular catabolism and anabolism, plays an important role in tumourigenesis and progression. In this study, we report the chemopreventive effect of the dietary compound ampelopsin (AMP) on breast carcinogenesis in vivo and in vitro, which acts by inhibiting the mTOR signalling pathway. Our study indicates that AMP treatment effectively suppresses 1-methyl-1-nitrosourea (MNU)-induced breast carcinogenesis in rats and inhibits 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and benzo[a]pyrene (B[a]P)-induced cellular carcinogenesis. Additionally, AMP inhibits the growth of breast cancer cells in vitro and in vivo. The activity of mTOR kinase was found to be significantly increased in a time-dependent manner during chronic breast carcinogenesis, and this increase can be suppressed by AMP co-treatment. AMP also effectively suppresses mTOR activity in breast cancer MDA-MB-231 cells. We also demonstrated that AMP is an effective mTOR inhibitor that binds to one site on the mTOR target in two ways. Further studies confirmed that AMP inhibits the activation of Akt, suppresses the formation of mTOR complexes (mTORC)1/2 by dissociating regulatory-associated protein of mTOR and rapamycin-insensitive companion of mTOR and, consequently, decreases the activation of the downstream targets of mTOR, including ribosomal p70-S6 kinase, ribosomal protein S6, eukaryotic translation initiation factor 4B and eukaryotic translation initiation factor 4E-binding protein 1. These finding suggest that AMP is a bioactive natural chemopreventive agent against breast carcinogenesis and is an effective mTOR inhibitor that may be developed as a useful chemotherapeutic agent in the treatment of breast cancer.