Transforming growth factor (TGF)-β expression and activation mechanisms as potential targets for anti-tumor therapy and tumor imaging

SLC2A3 promotes tumor progression through lactic acid-promoted TGF-β signaling pathway in oral squamous cell carcinoma

BACKGROUNDS

Oral squamous cell carcinoma is a malignant tumor of the head and neck, and its molecular mechanism remains to be explored.

METHODS

By analyzing the OSCC data from the TCGA database, we found that SLC2A3 is highly expressed in OSCC patients. The expression level of SLC2A3 was verified by RT-PCR and western blotting in OSCC cell lines. The function of SLC2A3 in OSCC cell lines and Lactic acid in SLC2A3-knockdown OSCC cells were detected by colony formation, CCK8, transwell, and wound healing assays. The effect of SLC2A3 on tumor growth and metastasis was tested in vivo. GSEA and Western blot were used to analyze and validate tumor phenotypes and signaling pathway molecules.

RESULTS

We analyzed OSCC datasets in the TCGA database and found that SLC2A3 had abnormally high expression and was associated with poor prognosis. We also found that oral squamous cell carcinoma cells had increased proliferation, migration, invasion, EMT phenotype, and glycolysis due to SLC2A3 overexpression. Conversely, SLC2A3 knockdown had the opposite effect. Our in vivo experiments confirmed that SLC2A3 overexpression promoted tumor growth and metastasis while knockdown inhibited it. We also observed that high SLC2A3 expression led to EMT and the activation of the TGF-β signaling pathway, while knockdown inhibited it. Interestingly, exogenous lactic acid restored the EMT, proliferation, migration, and invasion abilities of oral cancer cells inhibited by knocking down SLC2A3.

CONCLUSIONS

Our study reveals that SLC2A3 expression was up-regulated in OSCC. SLC2A3 activates the TGF-β signaling pathway through lactic acid generated from glycolysis, thus regulating the biological behavior of OSCC.

Berberine Suppresses Lung Metastasis of Cancer via Inhibiting Endothelial Transforming Growth Factor Beta Receptor 1

This study investigated the effects of berberine (BBR) on pancreatic cancer (PC) lung metastasis and explored the underlying mechanisms, using a BALB/C-nu/nu nude mouse model injected with PC cells (AsPC-1). Intragastric administration of BBR dose-dependently improves survival of mice intravenously injected with AsPC-1 cells, and reduces lung metastasis. Especially, BBR significantly reduces lung infiltration of circulating tumor cells (CTCs) 24 h after AsPC-1 cells injection. In vitro, tumor cells (TCs) trigger endothelial barrier disruption and promote trans-endothelial migration of CFSE-labeled TCs. BBR treatment effectively ameliorates TC-induced endothelial disruption, an effect that is diminished by inhibiting transforming growth factor-β receptor 1 (TGFBR1). Blocking TGFBR1 blunts the anti-metastatic effect of BBR in vivo. Mechanistically, BBR binds to the intercellular portion of TGFBR1, suppresses its enzyme activities, and protects endothelial barrier disruption by TCs which express higher levels of TGF-β1. Hence, BBR might be a promising drug for reducing PC lung metastasis in clinical practice.

TGF-β1 Reduces Neutrophil Adhesion and Prevents Acute Vaso-Occlusive Processes in Sickle Cell Disease Mice

Sickle cell disease (SCD) patients experience chronic inflammation and recurrent vaso-occlusive episodes during their entire lifetime. Inflammation in SCD occurs with the overexpression of several inflammatory mediators, including transforming growth factor beta-1 (TGF-β1), a major immune regulator. In this study, we aimed to investigate the role played by TGF-β1 in vascular inflammation and vaso-occlusion in an animal model of SCD. Using intravital microscopy, we found that a daily dose of recombinant TGF-β1 administration for three consecutive days significantly reduced TNFα-induced leukocyte rolling, adhesion, and extravasation in the microcirculation of SCD mice. In contrast, immunological neutralization of TGF-β, in the absence of inflammatory stimulus, considerably increased these parameters. Our results indicate, for the first time, that TGF-β1 may play a significant ameliorative role in vascular SCD pathophysiology, modulating inflammation and vaso-occlusion. The mechanisms by which TGF-β1 exerts its anti-inflammatory effects in SCD, however, remains unclear. Our in vitro adhesion assays with TNFα-stimulated human neutrophils suggest that TGF-β1 can reduce the adhesive properties of these cells; however, direct effects of TGF-β1 on the endothelium cannot be ruled out. Further investigation of the wide range of the complex biology of this cytokine in SCD pathophysiology and its potential therapeutical use is needed.

Isoform specific anti-TGFβ therapy enhances antitumor efficacy in mouse models of cancer

TGFβ is a potential target in cancer treatment due to its dual role in tumorigenesis and homeostasis. However, the expression of TGFβ and its inhibition within the tumor microenvironment has mainly been investigated in stroma-heavy tumors. Using B16 mouse melanoma and CT26 colon carcinoma as models of stroma-poor tumors, we demonstrate that myeloid/dendritic cells are the main sources of TGFβ1 and TGFβ3. Depending on local expression of TGFβ isoforms, isoform specific inhibition of either TGFβ1 or TGFβ3 may be effective. The TGFβ signature of CT26 colon carcinoma is defined by TGFβ1 and TGFβ1 inhibition results in tumor delay; B16 melanoma has equal expression of both isoforms and inhibition of either TGFβ1 or TGFβ3 controls tumor growth. Using T cell functional assays, we show that the mechanism of tumor delay is through and dependent on enhanced CD8+ T cell function. To overcome the local immunosuppressive environment, we found that combining TGFβ inhibition with immune checkpoint blockade results in improved tumor control. Our data suggest that TGFβ inhibition in stroma poor tumors shifts the local immune environment to favor tumor suppression.

Overexpression of BAMBI and SMAD7 impacts prognosis of acute myeloid leukemia patients: A potential TERT non-canonical role

BACKGROUND

Bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) and mothers against decapentaplegic homolog 7 (SMAD7) are important transforming growth factor-β (TGF-β) signaling antagonists, however their roles in acute myeloid leukemia (AML) remains unclear. Telomerase reverse transcriptase (TERT) may be involved in regulating BAMBI and SMAD7 expressions; a role beyond telomeres that is not clinically validated yet.

OBJECTIVE

In this study, we examined the expression levels and prognostic values of BAMBI, SMAD7 and TERT and their association with AML patients' outcomes.

METHODS

Blood samples were collected from 74 de-novo AML patients and 16 controls. Real-time quantitative PCR (qRT-PCR) was performed to analyze BAMBI, SMAD7 and TERT expressions.

RESULTS

BAMBI and SMAD7 expression in AML were significantly upregulated versus controls (p< 0.05). BAMBI, SMAD7 and TERT levels were significantly correlated together (p< 0.001). Kaplan-Meier analysis indicated that patients with high BAMBI, SMAD7 and TERT expression levels had markedly shorter event free survival (EFS) and overall survival (OS) time (p< 0.01). Furthermore, multivariate analysis revealed that only high BAMBI expression was an independent risk factor for OS (p= 0.001).

CONCLUSIONS

BAMBI is a novel biomarker in predicting prognosis in AML patients. Moreover, a potential interplay is found between BAMBI, SMAD7 and TERT in AML pathogenies.

Evaluating Deep Learning models for predicting ALK-5 inhibition

Computational methods have been widely used in drug design. The recent developments in machine learning techniques and the ever-growing chemical and biological databases are fertile ground for discoveries in this area. In this study, we evaluated the performance of Deep Learning models in comparison to Random Forest, and Support Vector Regression for predicting the biological activity (pIC₅₀) of ALK-5 inhibitors as candidates to treat cancer. The generalization power of the models was assessed by internal and external validation procedures. A deep neural network model obtained the best performance in this comparative study, achieving a coefficient of determination of 0.658 on the external validation set with mean square error and mean absolute error of 0.373 and 0.450, respectively. Additionally, the relevance of the chemical descriptors for the prediction of biological activity was estimated using Permutation Importance. We can conclude that the forecast model obtained by the deep neural network is suitable for the problem and can be employed to predict the biological activity of new ALK-5 inhibitors.

A Novel TGF-β Risk Score Predicts the Clinical Outcomes and Tumour Microenvironment Phenotypes in Bladder Cancer

Background

The TGF-β pathway plays critical roles in numerous malignancies. Nevertheless, its potential role in prognosis prediction and regulating tumour microenvironment (TME) characteristics require further elucidation in bladder cancer (BLCA).

Methods

TGF-β-related genes were comprehensively summarized from several databases. The TCGA-BLCA cohort (training cohort) was downloaded from the Cancer Genome Atlas, and the independent validation cohorts were gathered from Xiangya Hospital (Xinagya cohort) and Gene Expression Omnibus. Initially, we identified differentially expressed TGF-β genes (DEGs) between cancer and normal tissues. Subsequently, univariate Cox analysis was applied to identify prognostic DEGs, which were further used to develop the TGF-β risk score by performing LASSO and multivariate Cox analyses. Then, we studied the role of the TGF-β risk score in predicting prognosis and the TME phenotypes. In addition, the role of the TGF-β risk score in guiding precision treatments for BLCA has also been assessed.

Results

We successfully constructed a TGF-β risk score with an independent prognostic prediction value. A high TGF-β risk score indicated an inflamed TME, which was supported by the positive relationships between the risk score, enrichment scores of anticancer immunity steps, and the infiltration levels of tumour-infiltrating immune cells. In addition, the risk score positively correlated with the expression of several immune checkpoints and the T cell inflamed score. Consistently, the risk score was positively related to the enrichment scores of most immunotherapy-positive pathways. In addition, the sensitivities of six common chemotherapeutic drugs were positively associated with the risk score. Furthermore, higher risk score indicated higher sensitivity to radiotherapy and EGFR-targeted therapy. On the contrary, patients with low-risk scores were more sensitive to targeted therapies, including the blockade of FGFR3 and WNT-β-catenin networks.

Conclusions

We first constructed and validated a TGF-β signature that could predict the prognosis and TME phenotypes for BLCA. More importantly, the TGF-β risk score could aid in individual precision treatment for BLCA.

Inhibition of Wilms' Tumor Proliferation and Invasion by Blocking TGF-β Receptor I in the TGF-β/Smad Signaling Pathway

Wilms' tumor (WT) is a common embryonal tumor, and nephrogenic rests play a critical role in WT development. The transforming growth factor β (TGF-β) signaling pathway is fundamental to embryo development and cell growth and proliferation. Moreover, TGF-β contributes to WT development, but the mechanisms of disease pathogenicity are unknown. This study investigated whether the TGF-β signaling pathway was involved in WT and whether blocking TβRI receptor inhibited WT growth, proliferation, and invasion. A total of 60 WT patients with clinical data and surgical specimens were evaluated. Immunohistochemistry (IHC) was used to detect the expression of TGF-β1 and P-smad2/3. In vitro, the proliferation, migration, apoptosis, and epithelial-mesenchymal transition (EMT) protein expression were analyzed using the CCK8 assay, wound healing assay, transwell assay, flow cytometry, and western blot, respectively. In vivo, tumor morphology, tumor size, toxicity, and EMT protein expression were analyzed in tumor-bearing mice treated with a TβRI kinase inhibitor or PBS. High protein levels of TGF-β1 and P-samd2/3 were associated with clinical stage and metastasis or invasion. TβRI inhibition effectively suppressed WT proliferation and migration and promoted apoptosis in the human WT cell line G401, consequently decreasing EMT protein expression. In addition, the TβRI kinase inhibitor significantly impaired the subcutaneous growth of WT. It is worth noting that treatment with the TβRI kinase inhibitor did not cause liver and kidney injury. Our results indicate that the TGF-β/Smad signaling pathway plays a crucial role in WT progression. Blocking the TβRI receptor may be a novel strategy to treat and prevent WT.

Roles of fibrinolytic factors in the alterations in bone marrow hematopoietic stem/progenitor cells during bone repair

In bone tissues, metabolic turnover through bone resorption by osteoclasts and bone formation by osteoblasts, termed bone remodeling, is strictly controlled and maintains homeostasis. Fibrinolytic factors are expressed in osteoclasts and osteoblasts, and are involved in bone remodeling through bone resorption and formation. The repair/regeneration process after bone injury is divided into the acute inflammatory, repair, and remodeling stages. Osteoblasts, osteoclasts, chondrocytes, and macrophages involved in the bone repair process originate from hematopoietic stem/progenitor cells (HSPCs) and mesenchymal stem cells (MSCs) in the bone marrow. Therefore, stem cells in the bone marrow may be strongly influenced by bone injury. The urokinase-type PA (u-PA)/plasminogen (Plg) system functions in macrophage accumulation/phagocytosis through chemokines in the acute inflammatory stage, and Plg increases blood vessel-related growth factor expression, being involved in vascularization in mice. Plasminogen activator inhivitor-1 (PAI-1) causes bone loss and delayed bone repair through the inhibition of osteoblast differentiation in a drug-induced diabetes model in mice. Plg is considered to induce transforming growth factor-β (TGF-β) production in macrophages in the bone repair process, TGF-β release from the extracellular matrix through the activation of matrix metalloproteinase-9 (MMP-9), and stromal cell-derived factor-1 (SDF-1) expression in endosteal preosteoblasts, leading to the induction of bone marrow HSPCs in mice. Based on the above, establishment of a fibrinolytic factor-targeting method efficiently promoting bone repair/regeneration and fracture healing, and development of a new osteoporosis treatment method and diagnostic marker are awaited.

Pin1 Plays Essential Roles in NASH Development by Modulating Multiple Target Proteins

Pin1 is one of the three known prolyl-isomerase types and its hepatic expression level is markedly enhanced in the obese state. Pin1 plays critical roles in favoring the exacerbation of both lipid accumulation and fibrotic change accompanying inflammation. Indeed, Pin1-deficient mice are highly resistant to non-alcoholic steatohepatitis (NASH) development by either a high-fat diet or methionine-choline-deficient diet feeding. The processes of NASH development can basically be separated into lipid accumulation and subsequent fibrotic change with inflammation. In this review, we outline the molecular mechanisms by which increased Pin1 promotes both of these phases of NASH. The target proteins of Pin1 involved in lipid accumulation include insulin receptor substrate 1 (IRS-1), AMP-activated protein kinase (AMPK) and acetyl CoA carboxylase 1 (ACC1), while the p60 of the NF-kB complex and transforming growth factor β (TGF-β) pathway appear to be involved in the fibrotic process accelerated by Pin1. Interestingly, Pin1 deficiency does not cause abnormalities in liver size, appearance or function. Therefore, we consider the inhibition of increased Pin1 to be a promising approach to treating NASH and preventing hepatic fibrosis.

IFITM3/STAT3 axis promotes glioma cells invasion and is modulated by TGF-β

Glioma is the most aggressive primary brain tumor. We have previously provided evidence that IFITM3 promoted glioma cells migration. However, the mechanism of how IFITM3 regulates glioma cells invasion and whether IFITM3 participates in TGF-β-mediated glioma invasion are still unknown. In this paper, we proved that IFITM3 was notably up-regulated in glioma tissues. Knockdown of IFITM3 suppressed STAT3 phosphorylation in vitro, and a specific STAT3 inhibitor AG490 reversed IFITM3-induced invasion of glioma cells. Furthermore, IFITM3 expression was induced by TGF-β in glioma and IFITM3 knockdown abolished TGF-β-mediated glioma cells invasion. Collectively, the results indicate that IFITM3/STAT3 axis may promote TGF-β-induced glioma cells invasion. This study provided some suggestions for the clinical treatment of the brain tumor.

LncRNA-ATB promotes TGF-β-induced glioma cells invasion through NF-κB and P38/MAPK pathway

Glioma constitutes the most aggressive primary intracranial malignancy in adults. We previously showed that long noncoding RNA activated by TGF-β (lncRNA-ATB) promoted the glioma cells invasion. However, whether lncRNA-ATB is involved in TGF-β-mediated invasion of glioma cells remains unknown. In this study, quantitative real-time polymerase chain reaction and western blot analysis were used for detecting the mRNA and protein expression of related genes, respectively. Transwell assay was performed to assess the impact of lncRNA-ATB on TGF-β-induced glioma cells migration and invasion. Immunofluorescence staining was utilized to characterize related protein distribution. Results showed that TGF-β upregulated lncRNA-ATB expression in glioma LN-18 and U251 cells. Overexpression of lncRNA-ATB activated nuclear factor-κB (NF-κB) pathway and promoted P65 translocation into the nucleus, thus facilitated glioma cells invasion stimulated by TGF-β. Similarly, lncRNA-ATB markedly enhanced TGF-β-mediated invasion of glioma cells through activation P38 mitogen-activated protein kinase (P38/MAPK) pathway. Moreover, both the NF-κB selected inhibitor pyrrolidinedithiocarbamate ammonium and P38/MAPK specific inhibitor SB203580 partly reversed lncRNA-ATB induced glioma cells invasion mediated by TGF-β. Collectively, this study revealed that lncRNA-ATB promotes TGF-β-induced glioma cell invasion through NF-κB and P38/MAPK pathway and established a detailed framework for understanding the way how lncRNA-ATB performs its function in TGF-β-mediated glioma invasion.

TNF-α is a potential therapeutic target to overcome sorafenib resistance in hepatocellular carcinoma

Background

The role of tumor necrosis factor alpha (TNF-α) in targeted therapy for hepatocellular carcinoma (HCC) remains largely unknown. The current study aimed to clarify the mechanistic effects of targeting TNF-α to overcome sorafenib resistance in HCC.

Methods

A correlation of TNF-α expression with the prognosis was analyzed in 62 HCC patients who underwent surgical resection and subsequent received adjuvant sorafenib treatment. The relation of TNF-α expression and sorafenib sensitivity was determined in different HCC cell lines. The combined therapeutic effects of sorafenib and ulinastatin, which could inhibit TNF-α expression, on HCC were examined in vitro and in vivo.

Findings

High TNF-α expression was correlated with poor outcomes in HCC patients who received adjuvant sorafenib after surgery. In vitro experiments showed that TNF-α promotes HCC cell resistant to sorafenib through inducing epithelial-mesenchymal transition (EMT). Notably, the current study revealed that sorafenib has no significant influence on the expression and secretion of TNF-α, and sorafenib had limited effectiveness on reversing EMT in HCC cells with high TNF-α expression. Inhibiting the expression of TNF-α with ulinastatin significantly enhanced the anti-tumor effect of sorafenib on HCC cells with high expression of TNF-α in vitro and in vivo.

Interpretation: Our findings indicate that TNF-α may serve as a novel predictor of sorafenib sensitivity in HCC patients. Sorafenib combined with ulinastatin may improve the effectiveness of treatment of HCC in patients with high expression of TNF-α.

Fund

This work was supported by grants from the National Natural Science Foundation of China (no.81572398; no.81672419), the Science and Technology Planning Project of Guangdong Province (no. 2017A010105003; no.2015A050502023; no.2016A020216010), and the Natural Science Foundation of Guangdong Province (no.2014A030313061; no. 2013B021800101).

BAMBI is a novel HIF1-dependent modulator of TGFβ-mediated disruption of cell polarity during hypoxia

Hypoxia and loss of cell polarity are common features of malignant carcinomas. Hypoxia-inducible factor 1 (HIF1) is the major regulator of cellular hypoxia response and mediates the activation of ∼300 genes. Increased HIF1 signaling is known to be associated with epithelial-mesenchymal transformation. Here, we report that hypoxia disrupts polarized epithelial morphogenesis of MDCK cells in a HIF1α-dependent manner by modulating the transforming growth factor-β (TGFβ) signaling pathway. Analysis of potential HIF1 targets in the TGFβ pathway identified the bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI), a transmembrane glycoprotein related to the type I receptors of the TGFβ family, whose expression was essentially lost in HIF1-depleted cells. Similar to what was observed in HIF1-deficient cells, BAMBI-depleted cells failed to efficiently activate TGFβ signaling and retained epithelial polarity during hypoxia. Taken together, we show that hypoxic conditions promote TGFβ signaling in a HIF1-dependent manner and BAMBI is identified in this pathway as a novel HIF1-regulated gene that contributes to hypoxia-induced loss of epithelial polarity.

Roles of plasminogen in the alterations in bone marrow hematopoietic stem cells during bone repair

We previously revealed that stromal cell-derived factor-1 (SDF-1) is involved in the changes in the number of bone marrow stem cells during the bone repair process in mice. Moreover, we reported that plasminogen (Plg) deficiency delays bone repair and the accumulation of macrophages at the site of bone damage in mice. We investigated the roles of Plg in the changes in bone marrow stem cells during bone repair. We analyzed the numbers of hematopoietic stem cells (HSC) and mesenchymal stem cells (MSCs) within bone marrow from Plg-deficient and wild-type mice after a femoral bone injury using flow cytometric analysis. Plg deficiency significantly blunted a decrease in the number of HSCs after bone injury in mice, although it did not affect an increase in the number of MSCs. Plg deficiency significantly blunted the number of SDF-1- and Osterix- or SDF-1- and alkaline phosphatase-double-positive cells in the endosteum around the lesion as well as matrix metalloprotainase-9 (MMP-9) activity and mRNA levels of SDF-1 and transforming growth factor–β (TGF-β) elevated by bone injury. TGF-β signaling inhibition significantly blunted a decrease in the number of HSCs after bone injury. The present study showed that Plg is critical for the changes in bone marrow HSCs through MMP-9, TGF-β, and SDF-1 at the damaged site during bone repair in mice.

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We investigated the roles of plasminogen in bone marrow stem cell changes after bone injury in mice.

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Plasminogen deficiency blunted a decrease in the number of HSCs after bone injury.

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Plasminogen deficiency blunted the expression of SDF-1, TGF-β and MMP-9 at the damaged site.

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TGF-β signaling inhibition blunted a decrease in the number of HSCs after bone injury.

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Plasminogen is involved in HSC change through TGF-β and SDF-1 at the damaged site during bone repair.

Computational analyses of interactions between ALK-5 and bioactive ligands: insights for the design of potential anticancer agents

Activin Receptor-Like Kinase 5 (ALK-5) is related to some types of cancer, such as breast, lung, and pancreas. In this study, we have used molecular docking, molecular dynamics simulations, and free energy calculations in order to explore key interactions between ALK-5 and six bioactive ligands with different ranges of biological activity. The motivation of this work is the lack of crystal structure for inhibitor-protein complexes for this set of ligands. The understanding of the molecular structure and the protein-ligand interaction could give support for the development of new drugs against cancer. The results show that the calculated binding free energy using MM-GBSA, MM-PBSA, and SIE is correlated with experimental data with r² = 0.88, 0.80, and 0.94, respectively, which indicates that the calculated binding free energy is in excellent agreement with experimental data. In addition, the results demonstrate that H bonds with Lys232, Glu245, Tyr249, His283, Asp351, and one structural water molecule play an important role for the inhibition of ALK-5. Overall, we discussed the main interactions between ALK-5 and six inhibitors that may be used as starting points for designing new molecules to the treatment of cancer.

The effect of CT26 tumor-derived TGF-β on the balance of tumor growth and immunity

INTRODUCTION

TGF-β is an important target for many cancer therapies under development. In addition to suppressing anti-tumor immunity, it has pleiotropic direct pro- and anti- tumor effects. The actions of increased endogenous TGF-β production remain unclear, and may affect the outcomes of anti-TGF-β cancer therapy. We hypothesize that tumor-derived TGF-β (td-TGF-β) plays an important role in maintaining tumor remission by controlling tumor proliferation in vivo, and that decreasing td-TGF-β in the tumor microenvironment will result in tumor progression. The aim of this study was to examine the effect of TGF-β in the tumor microenvironment on the balance between its anti-proliferative and immunosuppressive effects.

METHODS

A murine BALB/c spontaneous colon adenocarcinoma cell line (CT26) was genetically engineered to produce increased active TGF-β (CT26-TGF-β), a dominant-negative soluble TGF-β receptor (CT26-TGF-β-R), or the empty neomycin cassette as control (CT26-neo). In vitro proliferation rates were measured. For in vivo studies, the three cell lines were injected into syngeneic BALB/c mice, and tumor growth was measured over time. Immunodeficient BALB/c nude mice were used to investigate the role of T and B cells.

RESULTS

In vitro, CT26-TGF-β-R and CT26-TGF-β cells showed increased and suppressed proliferation, respectively, compared to control (CT26-neo), confirming TGF-β has direct anti-tumor effects. In vivo, we found that CT26-TGF-β-R cells displayed slower growth compared to control, likely secondary to reduced suppression of anti-tumor immunity, as this effect was ablated in immunodeficient BALB/c nude mice. However, CT26-TGF-β cells (excess TGF-β) exhibited rapid early growth compared to control, but later failed to progress. The same pattern was shown in immunodeficient BALB/c nude mice, suggesting the effect on tumor growth is direct, with minimal immune system involvement. There was minimal effect on systemic antitumor immunity as determined by peripheral antigen-specific splenocyte type 1 cytokine production and tumor growth rate of CT26-neo on the contralateral flank of the same mice.

CONCLUSION

Although TGF-β has opposing effects on tumor growth, this study showed that excessive td-TGF-β in the tumor microenvironment renders the tumor non-proliferative. Depleting excess td-TGF-β may release this endogenous tumor suppressive mechanism, thus triggering the progression of the tumor. Therefore, our findings support cautions against using anti-TGF-β strategies in treating cancer, as this may tip the balance of anti-immunity vs. anti-tumor effects of TGF-β, leading to tumor progression instead of remission.

Airway administration of a highly versatile peptide-based liposomal construct for local and distant antitumoral vaccination

With the discovery of tumor-associated antigens such as ErbB2, vaccination is considered as a promising strategy to prevent the development of cancer or treat the existing disease. Among routes of immunization, the respiratory route provides the opportunity to develop non-invasive approach for vaccine delivery. In the current study, this administration route was used in order to investigate the potency of a highly versatile di-epitopic liposomal construct to exhibit local or distant antitumoral efficiency after prophylactic or therapeutic vaccination in mice. Well-characterized liposomes, containing the ErbB2 (p63-71) TCD8(+) and HA (p307-319) TCD4(+) peptide epitopes and the Pam2CAG adjuvant, were formulated and administered into the airway of naïve BALB/c mice. The nanoparticle vaccine candidate induced local and specific systemic immune response, as measured by immune cell infiltration and chemokine and cytokine production in BALF or lung tissue, and by spleen T-cell activation ex vivo, respectively. This potent immune response resulted in an efficient antitumor activity against both lung and solid s.c. tumors. Interestingly, the antitumor efficacy was observed after both prophylactic and therapeutic vaccinations, which are the most judicious ones to fight cancer. Our data showed an undeniable interest of liposomal peptide-based vaccines in antitumor vaccination by the respiratory route, opening new perspectives for cancer treatment.

Heparin inhibits activation of latent transforming growth factor-β1

AIM

Besides acting as an anticoagulant, heparin has antifibrotic effects. Transforming growth factor-β1 (TGF-β1) is secreted from cells as latent TGF-β1 (LTGF-β1). LTGF-β1 consists of TGF-β1 and latency-associated peptide (LAP). To be biologically active, TGF-β1 has to be released from LAP. Heparin binds to LAP as well as TGF-β1. This study was performed to explore the biological effect of the interaction of heparin with LTGF-β1.

MATERIALS AND METHODS

TGF-β1 was measured by ELISA. Furin-like proprotein convertase activity was assayed using the fluorogenic substrate, Pyr-Arg-Thr-Lys-Arg-AMC.

RESULTS

Heparin did not interfere with the receptor binding of TGF-β1, but inhibited furin-like proprotein convertase-mediated activation of platelet LTGF-β1. This was not by inhibition of the enzyme because heparin did not inhibit the activity of furin-like proprotein convertase. In addition, heparin inhibited acid activations of recombinant small LTGF-β1, platelet LTGF-β1 and LTGF-β1s secreted in the supernatant of cultured cells. Low-molecular-weight heparins, including dalteparin, enoxaparin and nadroparin, also had inhibitory effects on furin-like proprotein convertase-mediated or acid activation of platelet LTGF-β1.

CONCLUSION

The findings suggest that heparin renders LTGF-β1 resistant to activation, possibly by binding simultaneously to TGF-β1 and LAP. Inhibition of LTGF-β1 activation by heparin may in part account for its antifibrotic effects.

The platelet-cancer loop

The relationship between cancer and thrombosis has been established since 1865 when Armand Trousseau described superficial thrombophlebitis as forewarning sign of occult visceral malignancy. Platelets are the primary hemostatic tool and play a primordial role in cancer-induced thrombosis. Tumor-induced numerical and functional platelet abnormalities have been described in conjunction to changes in coagulation. Such changes are reported even in the absence of clinically detectable thrombosis and correlate with tumor progression and metastasis. Reciprocally, platelets seem to interplay with the tumors and the immune system, both directly and indirectly favoring tumor progressions, tethering and distant spread. A number of growth factors supporting tumor growth, angiogenesis and metastasis are released from the platelets. A reciprocating loop of tumor-induced platelet activation/platelet-induced tumor growth and dissemination is initiated, acting as a thrombosis trigger/tumor amplifier. Recent studies have demonstrated that the use of anti-platelet agents can break this loop resulting in a reduction of short-term risk for incident cancer, cancer mortality and metastasis. The beneficial effect in reduction in cancer-induced thrombosis remains to be established. The current review aims at shedding the light on the intimate reciprocal cross-talk between platelets and cancer and on exploring the potential beneficial effect of anti-platelet agents in breaking the deadly loop of tumor amplification.

Plasminogen plays a crucial role in bone repair

The further development in research of bone regeneration is necessary to meet the clinical demand for bone reconstruction. Plasminogen is a critical factor of the tissue fibrinolytic system, which mediates tissue repair in the skin and liver. However, the role of the fibrinolytic system in bone regeneration remains unknown. Herein, we investigated bone repair and ectopic bone formation using plasminogen-deficient (Plg⁻/⁻) mice. Bone repair of the femur is delayed in Plg⁻/⁻ mice, unlike that in the wild-type (Plg⁺/⁺) mice. The deposition of cartilage matrix and osteoblast formation were both decreased in Plg⁻/⁻ mice. Vessel formation, macrophage accumulation, and the levels of vascular endothelial growth factor (VEGF) and transforming growth factor-β (TGF-β) were decreased at the site of bone damage in Plg⁻/⁻ mice. Conversely, heterotopic ossification was not significantly different between Plg⁺/⁺ and Plg⁻/⁻ mice. Moreover, angiogenesis, macrophage accumulation, and the levels of VEGF and TGF-β were comparable between Plg⁺/⁺ and Plg⁻/⁻ mice in heterotopic ossification. Our data provide novel evidence that plasminogen is essential for bone repair. The present study indicates that plasminogen contributes to angiogenesis related to macrophage accumulation, TGF-β, and VEGF, thereby leading to the enhancement of bone repair.

Computational studies of TGF-βRI (ALK-5) inhibitors: analysis of the binding interactions between ligand-receptor using 2D and 3D techniques

ALK-5 (Activin-Like Kinase 5) is a biological receptor involved in a variety of pathological processes such as cancer and fibrosis. ALK-5 receptor propagates an intracellular signaling that forms a protein complex capable of reaching the nucleus and modulating the gene transcription. In the present study, comparative molecular field analysis (CoMFA) and hologram quantitative structure-activity relationship (HQSAR) studies were conducted on a series of potent ALK-5 inhibitors. Significant correlation coefficients (CoMFA, r(2)=0.99 and q(2)=0.85; HQSAR, r(2)=0.92 and q(2)=0.72) were obtained, indicating the predictive potential of the 2D and 3D models for untested compounds. The models were then used to predict the potency of a test set, and the predicted values from the HQSAR and CoMFA models were in good agreement with the experimental results. The final QSAR models, along with the information obtained from 3D (steric and electrostatic) contour maps and 2D contribution maps, can be useful for the design of novel bioactive ligands.

Cervical cancer cells induce apoptosis in TCD4+ lymphocytes through the secretion of TGF-β

PURPOSE

Tumor cells are known to secrete cytokines that modify their microenvironment in order to favor their survival and continuous proliferation. In this work, we evaluated if TGF-β secreted in vitro by cervical cancer cells could interfere with the proliferation and survival of lymphocytes.

METHODS

Lymphocytes were obtained from peripheral blood of healthy human volunteers, and isolated by density gradient centrifugation and cultured in 96-well plates. Lymphocyte proliferation was induced with phytohemaglutinin and co-cultured with conditioned media (CM) from cervical cancer cell lines, and the inhibition of proliferation was evaluated after 72 h by the incorporated radioactivity and a CFSE-labeling assay. TGF-β quantification on these CM was evaluated by ELISA. Non-apoptotic cellular death was evaluated through disruption of cell membrane integrity by measuring the liberation of lactate dehydrogenase. The apoptosis process was evaluated by annexin-V and active caspase-3. The presence of CD4+ or CD8+ lymphocytes was evaluated by flow cytometry using specific antibodies.

RESULTS

It was found that the conditioned media from these cells significantly inhibited the proliferation of lymphocytes and induced them to go into apoptosis. Antibodies against TGF-β almost completely blocked this activity, suggesting that this cytokine is responsible for the inhibitory activity. When the induced apoptosis on subpopulations of lymphocytes was evaluated, it was detected that the CD4+ cells were specifically targeted.

CONCLUSIONS

Cervical cancer cells secrete TGF-β that inhibits lymphocyte proliferation and induces apoptosis in CD4+, but not in CD8+ lymphocytes.

Overlapping activities of TGF-β and Hedgehog signaling in cancer: therapeutic targets for cancer treatment

Recent advances in the field of cancer therapeutics come from the development of drugs that specifically recognize validated oncogenic or pro-metastatic targets. The latter may be mutated proteins with altered function, such as kinases that become constitutively active, or critical components of growth factor signaling pathways, whose deregulation leads to aberrant malignant cell proliferation and dissemination to metastatic sites. We herein focus on the description of the overlapping activities of two important developmental pathways often exacerbated in cancer, namely Transforming Growth Factor-β (TGF-β) and Hedgehog (HH) signaling, with a special emphasis on the unifying oncogenic role played by GLI1/2 transcription factors. The latter are the main effectors of the canonical HH pathway, yet are direct target genes of TGF-β/SMAD signal transduction. While tumor-suppressor in healthy and pre-malignant tissues, TGF-β is often expressed at high levels in tumors and contributes to tumor growth, escape from immune surveillance, invasion and metastasis. HH signaling regulates cell proliferation, differentiation and apoptosis, and aberrant HH signaling is found in a variety of cancers. We discuss the current knowledge on HH and TGF-β implication in cancer including cancer stem cell biology, as well as the current state, both successes and failures, of targeted therapeutics aimed at blocking either of these pathways in the pre-clinical and clinical settings.