Regulatory T cell: a protection for tumour cells

A mathematical model to study low-dose metronomic scheduling for chemotherapy

Metronomic chemotherapy refers to the frequent administration of chemotherapeutic agents at a lower dose and presents an attractive alternative to conventional chemotherapy with encouraging response rates. However, the schedule of the therapy, including the dosage of the drug, is usually based on empiricism. The confounding effects of tumor-endothelial-immune interactions during metronomic administration of drugs have not yet been explored in detail, resulting in an incomplete assessment of drug dose and frequency evaluations. The present study aimed to gain a mechanistic understanding of different actions of metronomic chemotherapy using a mathematical model. We have established an analytical condition for determining the dosage and frequency of the drug depending on its clearance rate for complete tumor elimination. The model also brings forward the immune-mediated clearance of the tumor during the metronomic administration of the chemotherapeutic agent. The results from the global sensitivity analysis showed an increase in the sensitivity of drug and immune-mediated killing factors toward the tumor population during metronomic scheduling. Our results emphasize metronomic scheduling over the maximum tolerated dose (MTD) and define a model-based approach for approximating the optimal schedule of drug administration to eliminate tumors while minimizing harm to the immune cells and the patient's body.

Identification and Validation of Basement Membrane Related LncRNA Signatures as a Novel Prognostic Model for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a significant cancer with limited treatments and a poor prognosis, with the basement membrane (BM) playing a crucial role in its initiation and growth. This study utilized data from The Cancer Genome Atlas and the Gene Expression Omnibus (GEO) databases to identify basement membrane-related genes differentially expressed in HCC. Through gene co-expression analysis, BM-associated long non-coding RNAs (lncRNAs) were discovered. LncRNAs related to HCC survival were selected via univariate analysis, and a prognostic model was constructed using LASSO regression and multivariate analysis. This model effectively classified HCC patients into high and low-risk groups, uncovering significant differences in prognosis, immune response, mutation, and drug sensitivity. Six BM-related lncRNAs (GSEC, MIR4435-2HG, AC092614.1, AC127521.1, LINC02580, and AC008050.1) were validated in normal and HCC cell lines, and the key role of AC092614.1 in regulating proliferation, migration, and invasion of HCC cells in vitro was explored. This research emphasizes the prognostic and therapeutic relevance of BM-related lncRNAs in HCC, highlighting AC092614.1's role in disease progression and as a potential target for targeted therapy.

Evaluation of regulatory T-cells in cancer immunotherapy: therapeutic relevance of immune checkpoint inhibition

The evolution of the complex immune system is equipped to defend against perilous intruders and concurrently negatively regulate the deleterious effect of immune-mediated inflammation caused by self and nonself antigens. Regulatory T-cells (Tregs) are specialized cells that minimize immune-mediated inflammation, but in malignancies, this feature has been exploited toward cancer progression by keeping the antitumor immune response in check. The modulation of Treg cell infiltration and their induction in the TME (tumor microenvironment) alongside associated inhibitory molecules, both soluble or membranes tethered in the TME, have proven clinically beneficial in boosting the tumoricidal activity of the immune system. Moreover, Treg-associated immune checkpoints pose a greater obstruction in cancer immunotherapy. Inhibiting or blocking active immune checkpoint signaling in combination with other therapies has proven clinically beneficial. This review summarizes the ontogeny of Treg cells and their migration, stability, and function in the TME. We also elucidate the Treg-associated checkpoint moieties that impede effective antitumor activity and harness these molecules for effective and targeted immunotherapy against cancer nuisance.

A new target of radiotherapy combined with immunotherapy: regulatory T cells

Radiotherapy is one important treatment for malignant tumours. It is widely believed today that radiotherapy has not only been used as a local tumour treatment method, but also can induce systemic anti-tumour responses by influencing the tumour microenvironment, but its efficacy is limited by the tumour immunosuppression microenvironment. With the advancement of technology, immunotherapy has entered a golden age of rapid development, gradually occupying a place in clinical tumour treatment. Regulatory T cells (Tregs) widely distributing in the tumour microenvironment play an important role in mediating tumour development. This article analyzes immunotherapy, the interaction between Tregs, tumours and radiotherapy. It briefly introduces immunotherapies targeting Tregs, aiming to provide new strategies for radiotherapy combined with Immunotherapy.

Immunomodulatory roles of PARPs: Shaping the tumor microenvironment, one ADP-ribose at a time

PARPs encompass a small yet pervasive group of 17 enzymes that catalyze a post-translational modification known as ADP-ribosylation. PARP1, the founding member, has received considerable focus; however, in recent years, the spotlight has shifted to other members within the PARP family. In this opinion piece, we first discuss surprising findings that some FDA-approved PARP1 inhibitors activate innate immune signaling in cancer cells that harbor mutations in the DNA repair pathway. We then discuss hot-off-the-press genetic and pharmacological studies that reveal roles for PARP7, PARP11, and PARP14 in immune signaling in both tumor cells and tumor-associated immune cells. We conclude with thoughts on tuning PARP1-inhibitor-mediated innate immune activation and explore the unrealized potential for small molecule modulators of other PARP family members as next-generation immuno-oncology drugs.

Radiation for hematologic malignancies: from cell killing to immune cell priming

Over the past half-century, the role of radiotherapy has been revolutionized, in part, by a shift from intent to directly kill cancer cells to the goal of priming anti-tumor immune responses that attack both irradiated and non-irradiated tumors. Stimulation of anti-tumor immunity depends on the interplay between radiation, the tumor microenvironment, and the host immune system, which is a burgeoning concept in cancer immunology. While the interplay of radiotherapy and the immune system has been primarily studied in solid tumors, we are beginning to understand this interplay in hematological malignancies. The intent of this review is to lead readers through some of the important recent advances in immunotherapy and adoptive cell therapy, highlighting the best available evidence in support of incorporating radiation therapy and immunotherapy into the treatment of hematological malignancies. Evidence is presented regarding how radiation therapy 'converses' with the immune system to stimulate and enhance anti-tumor immune responses. This pro-immunogenic role of radiotherapy can be combined with monoclonal antibodies, cytokines and/or other immunostimulatory agents to enhance the regression of hematological malignancies. Furthermore, we will discuss how radiotherapy facilitates the effectiveness of cellular immunotherapies by acting as a "bridge" that facilitated CAR T cell engraftment and activity. These initial studies suggest radiotherapy may help catalyze a shift from using chemotherapy-intensive treatment to treatment that is "chemo-free" by combining with immunotherapy to target both the radiated and non-irradiated disease sites. This "journey" has opened the door for novel uses of radiotherapy in hematological malignancies due to its ability to prime anti-tumor immune responses which can augment immunotherapy and adoptive cell-based therapy.

Immunotherapy of Equine Sarcoids—From Early Approaches to Innovative Vaccines

Horses and other equid species are frequently affected by bovine papillomavirus type 1 and/or 2 (BPV1, BPV2)-induced skin tumors termed sarcoids. Although sarcoids do not metastasize, they constitute a serious health problem due to their BPV1/2-mediated resistance to treatment and propensity to recrudesce in a more severe, multiple form following accidental or iatrogenic trauma. This review provides an overview on BPV1/2 infection and associated immune escape in the equid host and presents early and recent immunotherapeutic approaches in sarcoid management.

Type 1 interferon mediated signaling is indispensable for eliciting anti-tumor responses by Mycobacterium indicus pranii

Introduction

The evolving tumor secretes various immunosuppressive factors that reprogram the tumor microenvironment (TME) to become immunologically cold. Consequently, various immunosuppressive cells like Tregs are recruited into the TME which in turn subverts the anti-tumor response of dendritic cells and T cells.Tumor immunotherapy is a popular means to rejuvenate the immunologically cold TME into hot. Mycobacterium indicus pranii (MIP) has shown strong immunomodulatory activity in different animal and human tumor models and has been approved for treatment of lung cancer (NSCLC) patients as an adjunct therapy. Previously, MIP has shown TLR2/9 mediated activation of antigen presenting cells/Th1 cells and their enhanced infiltration in mouse melanoma but the underlying mechanism by which it is modulating these immune cells is not yet known.

Results

This study reports for the first time that MIP immunotherapy involves type 1 interferon (IFN) signaling as one of the major signaling pathways to mediate the antitumor responses. Further, it was observed that MIP therapy significantly influenced frequency and activation of different subsets of T cells like regulatory T cells (Tregs) and CD8+ T cells in the TME. It reduces the migration of Tregs into the TME by suppressing the expression of CCL22, a Treg recruiting chemokine on DCs and this process is dependent on type 1 IFN. Simultaneously, in a type 1 IFN dependent pathway, it enhances the activation and effector function of the immunosuppressive tumor resident DCs which in turn effectively induce the proliferation and effector function of the CD8⁺ T cells.

Conclusion

This study also provides evidence that MIP induced pro-inflammatory responses including induction of effector function of conventional dendritic cells and CD8⁺ T cells along with reduction of intratumoral Treg frequency are essentially mediated in a type 1 IFN-dependent pathway.

Long Noncoding RNA: Shining Stars in the Immune Microenvironment of Gastric Cancer

Gastric cancer (GC) is a kind of malignant tumor disease that poses a serious threat to human health. The GC immune microenvironment (TIME) is a very complex tumor microenvironment, mainly composed of infiltrating immune cells, extracellular matrix, tumor-associated fibroblasts, cytokines and chemokines, all of which play a key role in inhibiting or promoting tumor development and affecting tumor prognosis. Long non-coding RNA (lncRNA) is a non-coding RNA with a transcript length is more than 200 nucleotides. LncRNAs are expressed in various infiltrating immune cells in TIME and are involved in innate and adaptive immune regulation, which is closely related to immune escape, migration and invasion of tumor cells. LncRNA-targeted therapeutic effect prediction for GC immunotherapy provides a new approach for clinical research on the disease.

Bioreducible polymer-mediated delivery of oncolytic adenovirus can attenuate antiviral immune response and concurrently enhance induction of antitumor immune response to effectively prevent metastasis

Oncolytic virotherapy is highly promising and novel treatment modality for cancer. Several clinical trials with oncolytic viruses have illustrated that the potent antitumor efficacy of these viruses may rely on...

Blockade of TGF-βR improves the efficacy of doxorubicin by modulating the tumor cell motility and affecting the immune cells in a melanoma model

TGF-β contributes to drug resistance and the invasiveness of tumor cells and weakens the anti-tumor immune responses. The present study aimed at examining the efficacy of the combination of SB431542, as a specific inhibitor of TGF-βR, and doxorubicin in controlling the melanoma tumor in mice. The impact of the combination of the doxorubicin and SB431542 on the cell growth, apoptosis, migration, and invasiveness of B16-F10 cells was examined. Besides, the B16-F10 tumor was induced in C57BL/6 mice, and the effects of the mentioned treatment on the tumor volume, survival, and the exhaustion state of T cells were evaluated. Although the combination of doxorubicin and SB431542 did not exhibit synergism in the inhibition of cell growth and apoptosis induction, it efficiently prohibited the migration and the epithelial to mesenchymal transition of B16-F10 cells, and the combination of doxorubicin and SB431542 caused an increase in mRNA levels of E-cadherin and, on the other hand, led to a decline in the expression of Vimentin. Tumor volume and the survival of tumor-bearing mice were efficiently controlled by the combination therapy. This treatment also eventuated in a decrease in the percentage of PD-L1⁺, TCD4⁺, and TCD8⁺ cells as indicators of exhausted T cells within the spleens of tumor-bearing mice. Blockade of TGF-βR also propelled the RAW 264.7 cells towards an anti-tumor M1 macrophage phenotype. The inhibition of TGF-βR demonstrated a potential to increase the efficacy of doxorubicin chemotherapy by the means of affecting cellular motility and restoring the anti-tumor immune responses.

Inhibition of photodynamic therapy induced-immunosuppression with aminolevulinic acid leads to enhanced outcomes of tumors and pre-cancerous lesions

Photodynamic therapy (PDT) is a treatment option for tumors and pre-cancerous lesions, but it has immunosuppressive side effects that limit its effectiveness. Recent studies suggest that PDT-mediated immunosuppression occurs through a cyclooxygenase type 2 (COX-2) mediated pathway that leads to increases in regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs), which act as negative regulators of immune responses. Given this pathway, there are three main methods to block immunosuppression: i) Inhibiting the proliferation of Tregs, which can be achieved with the administration of cyclophosphamide or inhibitors of indoleamine 2,3-dioxygenase 1, an activator of Tregs; ii) inhibiting MDSCs by reducing hypoxia around the tumor to create an unfavorable environment or administering all-trans-retinoic acid, which converts MDSCs to a non-immunosuppressive state; and iii) inhibiting COX-2 through selective or non-selective COX-inhibitors. In the present review article, strategies that have shown increased efficacy of PDT in treating tumors and pre-cancerous lesions by blocking the immunosuppressive side effects are outlined and discussed.

Targeting Enclysis in Liver Autoimmunity, Transplantation, Viral Infection and Cancer

Persistent liver inflammation can lead to cirrhosis, which associates with significant morbidity and mortality worldwide. There are no curative treatments beyond transplantation, followed by long-term immunosuppression. The global burden of end stage liver disease has been increasing and there is a shortage of donor organs, therefore new therapies are desperately needed. Harnessing the power of the immune system has shown promise in certain autoimmunity and cancer settings. In the context of the liver, regulatory T cell (Treg) therapies are in development. The hypothesis is that these specialized lymphocytes that dampen inflammation may reduce liver injury in patients with chronic, progressive diseases, and promote transplant tolerance. Various strategies including intrinsic and extracorporeal expansion of Treg cells, aim to increase their abundance to suppress immune responses. We recently discovered that hepatocytes engulf and delete Treg cells by enclysis. Herein, we propose that inhibition of enclysis may potentiate existing regulatory T cell therapeutic approaches in patients with autoimmune liver diseases and in patients receiving a transplant. Moreover, in settings where the abundance of Treg cells could hinder beneficial immunity, such us in chronic viral infection or liver cancer, enhancement of enclysis could result in transient, localized reduction of Treg cell numbers and tip the balance towards antiviral and anti-tumor immunity. We describe enclysis as is a natural process of liver immune regulation that lends itself to therapeutic targeting, particularly in combination with current Treg cell approaches.

Preclinical Evaluation of Recombinant Human IL15 Protein Fused with Albumin Binding Domain on Anti-PD-L1 Immunotherapy Efficiency and Anti-Tumor Immunity in Colon Cancer and Melanoma

Simple Summary

In this manuscript, we reported that a newly developed recombinant human IL15 fused with albumin binding domain (hIL15-ABD) showed superior biological half-life, pharmacokinetic and anti-tumor immunity than wild-type (WT) hIL15. Our hIL-15-ABD can effectively enhance anti-tumor efficacy of anti-PD-L1 on colon cancer and melanoma animal models. The anti-tumor potential of hIL-15-ABD was associated with tumor microenvironment (TME) regulation, including the activation of NK cells and CD8⁺ T cells, the reduction of immunosuppressive cells (MDSCs and Tregs) and the suppression of immunosuppressive factors (IDO, FOXP3 and VEGF). In conclusion, our new hIL15-ABD combined with anti-PD-L1 antibody increased the activity of anti-tumor effector cells involved in both innate and adaptive immunities, decreased the TME’s immunosuppressive cells, and showed greater anti-tumor effect than that of either monotherapy. We suggested hIL15-ABD as the potential complementary agent may effectively augment the therapeutic efficacy of anti-PD-L1 antibody in colon cancer and melanoma model.

Abstract

Anti-PD-L1 antibody monotherapy shows limited efficacy in a significant proportion of the patients. A common explanation for the inefficacy is a lack of anti-tumor effector cells in the tumor microenvironment (TME). Recombinant human interleukin-15 (hIL15), a potent immune stimulant, has been investigated in clinical trial with encouraging results. However, hIL15 is constrained by the short half-life of hIL15 and a relatively unfavorable pharmacokinetics profile. We developed a recombinant fusion IL15 protein composed of human IL15 (hIL15) and albumin binding domain (hIL15-ABD) and explored the therapeutic efficacy and immune regulation of hIL-15, hIL15-ABD and/or combination with anti-PD-L1 on CT26 murine colon cancer (CC) and B16-F10 murine melanoma models. We demonstrated that hIL15-ABD has significant inhibitory effect on the CT26 and B16-F10 tumor growths as compared to hIL-15. hIL-15-ABD not only showed superior half-life and pharmacokinetics data than hIL-15, but also enhance anti-tumor efficacy of antibody against PD-L1 via suppressive effect on accumulation of Tregs and MDSCs and activation of NK and CD8+T cells. Immune suppressive factors including VEGF and IDO were also decreased by combination treatment. hIL15-ABD combined with anti-PD-L1 antibody increased the activity of anti-tumor effector cells involved in both innate and adaptive immunities, decreased the TME’s immunosuppressive cells, and showed greater anti-tumor effect than that of either monotherapy.

Increased production of matrix metalloproteinase-7 (MMP-7) by asbestos exposure enhances tissue migration of human regulatory T-like cells

The effects of asbestos on immunocompetent cells have been investigated. In particular, attention was paid to regulatory T cell function, which was observed using the HTLV-1 immortalized human polyclonal T cell line MT-2. Exposure to asbestos (approximately more than 25 μg/mL for 1-3 day) induced apoptosis, and we observed an increase in regulatory T cell function and acceleration of the cell cycle with continuous exposure to low concentrations of asbestos (5-10 μg/mL for more than eight months). Furthermore, cDNA microarray analysis in this study revealed that expression of matrix metalloproteinase-7 (MMP-7) was markedly higher in exposed sublines compared to original MT-2 cells. It was determined that MMP-7 had no effect on Treg function, as determined by examination of sublines and by addition of recombinant MMP-7 and neutralizing antibodies or inhibitors of MMP-7. However, when examining melting of the extracellular matrix (an MMP-7-mediated event) or the extent to which the MT-2 parent strain or long-term exposed subline cells pass through a fibronectin-coated filter, more filter passes were observed for the subline. These results suggest that the effect of asbestos fibers on Treg cells results in excessive migration of the tumor microenvironment through hypersecretion of MMP-7 together with an increase in suppressive function and enhancement of cell cycle progression. Therefore, one possible way to prevent the development of asbestos-induced cancer is to reduce the function (including MMP-7 production) or amount of Treg cells by physiologically active substances or food ingredients. Alternatively, it may be possible to invoke immune checkpoint treatments when carcinogenesis occurs.

The role of regulatory T cells in the pathogenesis and treatment of prostate cancer

Despite developments in the treatment of various cancers, prostate cancer is one of the deadliest diseases known to men. Systemic therapies such as androgen deprivation, chemotherapy, and radiation therapy have not been very successful in treating this disease. Numerous studies have shown that there is a direct relationship between cancer progression and inhibition of anti-tumor immune responses that can lead to progression of various malignancies, including prostate cancer. Interestingly, CD4⁺CD25⁺FoxP3⁺ regulatory T cells significantly accumulate and increase in draining lymph nodes and PBMCs of patients with prostate cancer and other solid tumors. In vivo and in vitro studies have shown that Tregs can suppress anti-tumor responses, which is directly related to the increased risk of cancer recurrence. Tregs are essential for preserving self-tolerance and inhibiting extra immune responses harmful to the host. Since the tumor-related antigens are mainly self-antigens, Tregs could play a major role in tumor progression. Accordingly, it has discovered that prostate cancer patients with higher Tregs have poor prognosis and low survival rates. However, anti-tumor responses can be reinforced by suppression of Tregs with using monoclonal antibodies against CD25 and CTLA-4. Therefore, depleting Tregs or suppressing their functions could be one of the effective ways for prostate cancer immunotherapy. The purpose of this review is to investigate the role of Treg cells in the progression of prostate cancer and to evaluate effective strategies for the treatment of prostate cancer by regulating Treg cells.

P21 activated kinase-1 (PAK1) in macrophages is required for promotion of Th17 cell response during helminth infection

CD4⁺T cells differentiate into distinct functional effector and inhibitory subsets are facilitated by distinct cytokine cues present at the time of antigen recognition. Maintaining a balance between T helper 17 (Th17) and regulatory T (Treg) cells are critical for the control of the immunopathogenesis of liver diseases. Here, by using the mouse model of helminth Schistosoma japonicum (Sjaponicum) infection, we show that the hepatic mRNA levels of P21‐activated kinase 1 (PAK1), a key regulator of the actin cytoskeleton, adhesion and cell motility, are significantly increased and associated with the development of liver pathology during Sjaponicum infection. In addition, PAK1‐deficient mice are prone to suppression of Th17 cell responses but increased Treg cells. Furthermore, PAK1 enhances macrophage activation through promoting IRF1 nuclear translocation in an NF‐κB‐dependent pathway, resulting in promoting Th17 cell differentiation through inducing IL‐6 production. These findings highlight the importance of PAK1 in macrophages fate determination and suggest that PAK1/IRF1 axis‐dependent immunomodulation can ameliorate certain T cell–based immune pathologies.

Calculation of immune cell proportion from batch tumor gene expression profile based on support vector regression

In addition to tumor cells, a large number of immune cells are found in the tumor microenvironment (TME) of cancer patients. Tumor-infiltrating immune cells play an important role in tumor progression and patient outcome. We improved the relative proportion estimation algorithm of immune cells based on RNA-seq gene expression profiling and solved the multiple linear regression model by support vector regression ([Formula: see text]-SVR). These steps resulted in increased robustness of the algorithm and more accurate calculation of the relative proportion of different immune cells in cancer tissues. This method was applied to the analysis of infiltrating immune cells based on 41 pairs of colorectal cancer tissues and normal solid tissues. Specifically, we compared the relative fractions of six types of immune cells in colorectal cancer tissues to those found in normal solid tissue samples. We found that tumor tissues contained a higher proportion of CD8 T cells and neutrophils, while B cells and monocytes were relatively low. Our pipeline for calculating immune cell proportion using gene expression profile data can be freely accessed from GitHub at https://github.com/gutmicrobes/EICS.git.

Metronomic chemotherapy combined with endocrine therapy: are we challenging some dogmas?

INTRODUCTION

Metronomic chemotherapy exerts its effects via inhibition of angiogenesis, immune modulation of the tumoral stroma, induction of senescence and apoptosis of tumor cells. Due to its favorable toxicity profile and its oral administration, metronomic chemotherapy arises as a promising alternative to be combined with endocrine therapy for the treatment of patients with luminal breast cancer.

AREAS COVERED

The present manuscript reviews the rationale supporting the combination of metronomic chemotherapy and endocrine therapy, discussing the studies that evaluated this regimen in the treatment of early-stage and metastatic breast cancer patients. Finally, we conclude by providing an expert opinion on the current role and perspectives for the combination of metronomic chemotherapy and endocrine therapy in the management of patients with luminal breast cancer.

EXPERT OPINION

Retrospective series and early-phase clinical trials have shown promising signs of activity and a favorable toxicity profile with this regimen, which warrants further investigation as a treatment option for luminal breast cancer patients.

Gastroenteropancreatic neuroendocrine neoplasms and inflammation: A complex cross-talk with relevant clinical implications

Neuroendocrine neoplasms (NENs) are a group of tumors originating from the neuroendocrine system. They mainly occur in the digestive system and the respiratory tract. It is well-know a strict interaction between neuroendocrine system and inflammation, which can play an important role in NEN carcinogenesis. Inflammatory mediators, which are produced by the tumor microenvironment, can favor cancer induction and progression, and can promote immune editing. On the other hand, a balanced immune system represents a relevant step in cancer prevention through the elimination of dysplastic and cancer cells. Therefore, an inflammatory response may be both pro- and anti-tumorigenic. In this review, we provide an overview concerning the complex interplay between inflammation and gastroenteropancreatic NENs, focusing on the tumorigenesis and clinical implications in these tumors.

Sorafenib- Taurine Combination Model for Hepatocellular Carcinoma Cells: Immunological Aspects

Sorafenib (Sor) is a multi-kinase inhibitor. It is recommended for the treatment of advanced hepatocellular carcinoma (HCC). However, Sor has severe and marked side effects. On the other hand, taurine (Tau) has been shown to enhance the therapeutic effects of cancer chemotherapy and also to enhance the function of leukocytes.

Here, we aimed to investigate the enhancing efficacy of Sor as well as minimizing its marked side effects by using Tau in combination in an immunological aspect. We evaluated the influence of Sor and Tau combination on the expression pattern of FOXP3 gene in HepG2 cells compared to peripheral blood mononuclear leukocytes (PBMCs) as control normal cells. Also, the levels of TGF-β and IL-10 released in culture media of both cells were determined. Our results revealed that, Tau reduced cytotoxicity of Sor on PBMC indicated by lactic dehyrogenase (LDH) release assay. In addition, Sor-Tau combination led to FOXP3 down-regulation in hepatic cancer cells (HepG2). The results showed also that, TGF-β levels decreased significantly in their culture media. In contrary, the cytokine increased in PBMCs culture media. Moreover, IL-10 was significantly elevated in the culture media of both cells. This study could open new avenues for the improvement of therapeutic efficacy of Sorafenib treated HCC patients by using Tau in combination.

Cancer-Derived Exosomes as Effectors of Key Inflammation-Related Players

Exosomes, a category of small lipid bilayer extracellular vesicles that are naturally secreted by many cells (both healthy and diseased), carry cargo made up of proteins, lipids, DNAs, and RNAs; all of which are functional when transferred to their recipient cells. Numerous studies have demonstrated the powerful role that exosomes play in the mediation of cell-to-cell communication to induce a pro-tumoral environment to encourage tumor progression and survival. Recently, considerable interest has developed in regard to the role that exosomes play in immunity; with studies demonstrating the ability of exosomes to either metabolically alter immune players such as dendritic cells, T cells, macrophages, and natural killer cells. In this review, we summarize the recent literature on the function of exosomes in regulating a key process that has long been associated with the progression of cancer-inflammation and immunity.

Virus-like particles for vaccination against cancer

Active immunotherapy of cancer aims to treat the disease by inducing effective cellular and humoral immune responses. Virus‐like particle‐based vaccines have evolved dramatically over the last few decades, greatly reducing morbidity and mortality of several infectious diseases and expectedly preventing cervical cancer caused by human papilloma virus. In contrast to these broad successes of disease prevention, therapeutic cancer vaccines remain to demonstrate clinical benefit. Yet, several preclinical and clinical trials have revealed promising results and are paving the way for medical breakthroughs. This study reviews and discusses the recent preclinical development and clinical trials in this field.

This article is categorized under:

Biology‐Inspired Nanomaterials > Protein and Virus‐Based Structures

Nanotechnology Approaches to Biology > Nanoscale Systems in Biology

Metronomic Chemotherapy: A Systematic Review of the Literature and Clinical Experience

Metronomic chemotherapy, continuous and dose-dense administration of chemotherapeutic drugs with lowered doses, is being evaluated for substituting, augmenting, or appending conventional maximum tolerated dose regimens, with preclinical and clinical studies for the past few decades. To date, the principle mechanisms of its action include impeding tumoral angiogenesis and modulation of hosts' immune system, affecting directly tumor cells, their progenitors, and neighboring stromal cells. Its better toxicity profile, lower cost, and easier use are main advantages over conventional therapies. The evidence of metronomic chemotherapy for personalized medicine is growing, starting with unfit elderly patients and also for palliative treatment. The literature reviewed in this article mainly demonstrates that metronomic chemotherapy is advantageous for selected patients and for certain types of malignancies, which make it a promising therapeutic approach for filling in the gaps. More clinical studies are needed to establish a solidified role for metronomic chemotherapy with other treatment models in modern cancer management.

Regulatory T Cells and Plasmacytoid Dendritic Cells Within the Tumor Microenvironment in Gastric Cancer Are Correlated With Gastric Microbiota Dysbiosis: A Preliminary Study

Substantial evidence indicates that gastric microbiota dysbiosis, immune system dysfunction especially immune escape are critical for gastric cancer (GC) occurrence and progression. As two important elements of tumor microenvironment (TME), the relationship between gastric microbiota and tumor-immune microenvironment is still unclear. Our present study aimed to explore the correlation between gastric mucosal microbiota in different microhabitats and its corresponding gastric immunosuppressive cells such as regulatory T cells (Tregs) and plasmacytoid dendritic cells (pDCs) in the TME. A cohort of 64 GC patients without preoperative chemotherapy was enrolled retrospectively, and 60 normal, 61 peritumoral and 59 tumoral tissues were obtained for gastric mucosal microbiota analysis and immunohistochemistry analysis. From different microhabitats, BDCA2⁺pDCs and Foxp3⁺Tregs were observed positively correlated, and increased in tumoral and peritumoral tissues compared to normal ones. The diversity, composition and function of gastric mucosal microbiota also changed more significantly in tumoral tissues than those in normal and peritumoral ones. With pearson's correlation analysis, we found that several non-abundant genera such as Stenotrophomonas and Selenomonas were positively correlated with BDCA2⁺pDCs and Foxp3⁺Tregs, respectively, while Comamonas and Gaiella were negatively correlated with BDCA2⁺pDCs and Foxp3⁺ Tregs, respectively. The increased BDCA2⁺pDCs and Foxp3⁺Tregs might be modulated by gastric mucosal microbiota, both participated in the immunosuppression microenvironment of GC, which might provide evidence to establish new strategies in antitumor therapy targeting on gastric microbiota.

Reduced hsa-miR-124-3p levels are associated with the poor survival of patients with hepatocellular carcinoma

Hsa-MicroRNA-124a-3p (hsa-miR-124-3p) is involved in tumor progression in certain malignant tumors. However, its function and clinical implication in hepatocellular carcinoma (HCC) have not yet been illustrated. In this study, we explored the expression and prognostic value of hsa-miR-124-3p in patients with HCC. Hsa-miR-124-3p expression in HCC was analyzed in silico, which was subsequently confirmed by quantitative PCR in 155 HCC biopsy samples. Overall survival (OS) and disease-free survival in HCC patients was evaluated by Kaplan-Meier survival analysis, and univariate and multivariate Cox proportional hazard models were used. The in silico results demonstrated that hsa-miR-124-3p was reduced in cell lines and tissues of HCC, and hsa-miR-124-3p expression was lower in HCC tumor samples than in normal liver tissues. Moreover, a decrease in hsa-miR-124-3p expression was closely correlated with tumor diameter (≥ 5 cm) and number of lesions (multiple). Lower hsa-miR-124-3p expression was shown to be correlated with a shorter OS and poor prognosis in HCC. Our findings demonstrate that hsa-miR-124-3p might be a potential target for the diagnosis and prognosis of HCC.

MicroRNA-302a/d inhibits the self-renewal capability and cell cycle entry of liver cancer stem cells by targeting the E2F7/AKT axis

BACKGROUND

There is increasing evidence that liver cancer stem cells (LCSCs) contribute to hepatocellular carcinoma (HCC) initiation and progression. MicroRNA (miRNA) plays a significant functional role by directly regulating respective targets in LCSCs-triggered HCC, however, little is known about the function of the miRNA-302 family in LCSCs.

METHODS

MiRNAs microarray was used to detect the miRNAs involved in LCSCs maintenance and differentiation. Biological roles and the molecular mechanism of miRNA-302a/d and its target gene E2F7 were detected in HCC in vitro. The expression and correlation of miRNA-302a/d and E2F7 in HCC patients was evaluated by quantitative PCR and Kaplan-Meier survival analysis.

RESULTS

We found that the miRNA-302 family was downregulated during the spheroid formation of HCC cells and patients with lower miRNA-302a/d expression had shorter overall survival (OS) and progression-free survival (PFS). Moreover, E2F7 was confirmed to be directly targeted and inhibited by miRNA-302a/d. Furthermore, concomitant low expression of miRNA-302a/d and high expression of E2F7 correlated with a shorter median OS and PFS in HCC patients. Cellular functional analysis demonstrated that miRNA-302a/d negatively regulates self-renewal capability and cell cycle entry of liver cancer stem cells via suppression of its target gene E2F7 and its downstream AKT/β-catenin/CCND1 signaling pathway.

CONCLUSIONS

Our data provide the first evidence that E2F7 is a direct target of miRNA-302a/d and miRNA-302a/d inhibits the stemness of LCSCs and proliferation of HCC cells by targeting the E2F7/AKT/β-catenin/CCND1 signaling pathway.

PNMA1, regulated by miR-33a-5p, promotes proliferation and EMT in hepatocellular carcinoma by activating the Wnt/β-catenin pathway

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors throughout the world. However, its mortality rate remains very high due to the absence of early diagnostic modalities and effective treatments, and its specific pathogenesis remains unclear. Here, we investigated the role of PNMA1 in the tumorigenesis of HCC. We found that PNMA1 was significantly upregulated in HCC. Clinically, higher expression of PNMA1 was associated with aggressive phenotypes and poor prognosis. Functionally, silencing of PNMA1 repressed proliferation in vitro and in vivo, and knockdown of PNMA1 suppressed tumor cell migration and invasion. Via GSEA analysis, we predicted that PNAM1 may be related to the epithelial-mesenchymal-transition and the Wnt signaling pathway. Both these assumptions were confirmed in our study. Furthermore, we proved that miR-33a-5p participated in the posttranscriptional regulation of PNMA1. Together, our findings suggested that PNMA1 participated in HCC progression and may be a potential biomarker and therapeutic target for HCC.

miR-30 Family Reduction Maintains Self-Renewal and Promotes Tumorigenesis in NSCLC-Initiating Cells by Targeting Oncogene TM4SF1

Increasing evidence indicates that tumor-initiating cells (TICs) are responsible for the occurrence, development, recurrence, and development of the drug resistance of cancer. MicroRNA (miRNA) plays a significant functional role by directly regulating targets of TIC-triggered non-small-cell lung cancer (NSCLC), but little is known about the function of the miR-30 family in TICs. In this study, we found the miR-30 family to be downregulated during the spheroid formation of NSCLC cells, and patients with lower miR-30a/c expression had shorter overall survival (OS) and progression-free survival (PFS). Moreover, transmembrane 4 super family member 1 (TM4SF1) was confirmed to be a direct target of miR-30a/c. Concomitant low expression of miR-30a/c and high expression of TM4SF1 correlated with a shorter median OS and PFS in NSCLC patients. miR-30a/c significantly inhibited stem-like characteristics in vitro and in vivo via suppression of its target gene TM4SF1, and then it inhibited the activity of the mTOR/AKT-signaling pathway. Thus, our data provide the first evidence that TM4SF1 is a direct target of miR-30a/c and miR-30a/c inhibits the stemness and proliferation of NSCLC cells by targeting TM4SF1, suggesting that miR-30a/c and TM4SF1 may be useful as tumor biomarkers for the diagnosis and treatment of NSCLC patients.

The impact of inflammation and cytokine expression of PM2.5 in AML

Environmental and health issues have become a major focus of research worldwide in recent years. Particulate matter with diameter ≤2.5 µm (PM2.5) is a common air pollutant that has been demonstrated to be associated with various diseases, including acute myeloid leukemia (AML). In the present study, the effects of PM2.5 on the proliferation and inflammation were assessed using three human acute myeloid cell lines (U937, HL-60 and KG-1a) in vitro. Additionally, the levels of several cytokines [interleukin (IL)-2, IL-10, IL-17A and tumor necrosis factor (TNF)α] in AML cells and Sprague Dawley rats were evaluated to investigate the effects of PM2.5 on cytokine expression in AML. The results revealed that PM2.5 was capable of enhancing inflammatory responses in AML cells, and increasing IL-2, IL-10, IL-17A and TNFα mRNA expression in AML cells to different degrees. Furthermore, PM2.5 increased IL-2 and IL-10 contents in rats following 12 weeks of exposure. These results suggested that PM2.5 may serve a role in promoting the occurrence and progression of leukemia by affecting cytokine expression, and that there may be various mechanisms active in different AML subtypes.

Tumor suppressive microRNA-124a inhibits stemness and enhances gefitinib sensitivity of non-small cell lung cancer cells by targeting ubiquitin-specific protease 14

Increasing evidence has shown that microRNAs (miRNAs) play a significant functional role by directly regulating respective targets in cancer stem cell (CSC)-induced non-small cell lung cancer (NSCLC) progression and resistance to therapy. In this study, we found that hsa-miR-124a was downregulated during spheroid formation of the NSCLC cell lines SPC-A1 and NCI-H1650 and NSCLC tissues compared with normal lung cells and tissues. Patients with lower hsa-miR-124a expression had shorter overall survival (OS) and progression free survival (PFS). Moreover, ubiquitin-specific protease 14 (USP14) was confirmed to be a direct target of hsa-miR-124a. Furthermore, concomitant low hsa-miR-124a expression and high USP14 expression were correlated with a shorter median OS and PFS in NSCLC patients. Cellular functional analysis verified that the tumor suppressor hsa-miR-124a negatively regulated cell growth and self-renewal, and promoted apoptosis and gefitinib sensitivity of lung cancer stem cells by suppressing its target gene USP14. Our results provide the first evidence that USP14 is a direct target of hsa-miR-124a, and that hsa-miR-124a inhibits stemness and enhances the gefitinib sensitivity of NSCLC cells by targeting USP14. Thus, hsa-miR-124a and USP14 may be useful as tumor biomarkers for the diagnosis and treatment of NSCLC.

DRR1 promotes glioblastoma cell invasion and epithelial-mesenchymal transition via regulating AKT activation

Metastatic invasion is the primary cause of treatment failure for GBM. EMT is one of the most important events in the invasion of GBM; therefore, understanding the molecular mechanisms of EMT is crucial for the treatment of GBM. In this study, high expression of DRR1 was identified to correlate with a shorter median overall and relapse-free survival. Loss-of-function assays using shDRR1 weakened the invasive potential of the GBM cell lines through regulation of EMT-markers. The expressions of p-AKT were significantly decreased after DRR-depletion in SHG44 and U373 cells. Moreover, the invasion was inhibited by the AKT inhibitor, MK-2206. The expression of Vimentin, N-cadherin, MMP-7, snail and slug was significantly inhibited by MK-2206, while the expression of E-cadherin was upregulated. Our results provide the first evidence that DRR1 is involved in GBM invasion and progression possibly through the induction of EMT activation by phosphorylation of AKT.

Expression and function of immune ligand-receptor pairs in NK cells and cancer stem cells: therapeutic implications

BACKGROUND

The interplay between the immune system and cancer cells has come to the forefront of cancer therapeutics, with novel immune blockade inhibitors being approved for the treatment of an increasing list of cancers. However, the majority of cancer patients still display or develop resistance to these promising drugs. It is possible that cancer stem cells (CSCs) are contributing to this therapeutic resistance. Although CSCs usually represent a small percentage of the total number of cancer cells, they are endowed with the ability of self-renewal and to produce differentiated progeny. Additionally, they have shown the capacity to establish tumors after transplantation to animals, even in small numbers. CSCs have also been found to be resistant to various anti-cancer therapies, including chemotherapy, radiation therapy and, more recently, immunotherapy. This is true despite the sensitivity of CSCs to lysis in vitro by natural killer (NK) cells, the main effector cells of the innate immune system. In this paper the expression of ligands specific for NK cells on CSCs, the intracellular network responsible for the expression of the NK cytotoxicity receptors, and the status of activation of NK cells in the tumor micro-environment are reviewed. The aim of this review is to highlight potential strategies for overcoming CSC immune resistance, thereby enhancing the efficacy of current and future anti-cancer therapies.

THERAPEUTIC IMPLICATIONS

NK cell activation in the tumor micro-environment through drugs neutralizing inhibitory immune receptors, and combined with other drugs harnessing the potential of the adaptive immune system, could be the most effective approach for attacking both stem cell and non-stem cell cancer populations.

Oncolytic adenovirus coexpressing interleukin-12 and decorin overcomes Treg-mediated immunosuppression inducing potent antitumor effects in a weakly immunogenic tumor model

Interleukin (IL)-12 is a potent antitumor cytokine. However, immunosuppressive tumor microenvironments containing transforming growth factor-β (TGF-β) attenuate cytokine-mediated antitumor immune responses. To enhance the efficacy of IL-12-mediated cancer immunotherapy, decorin (DCN) was explored as an adjuvant for overcoming TGF-β-mediated immunosuppression. We designed and generated a novel oncolytic adenovirus (Ad) coexpressing IL-12 and DCN (RdB/IL12/DCN). RdB/IL12/DCN-treated tumors showed significantly greater levels of interferon (IFN)-γ, tumor necrosis factor-α, monocyte chemoattractant protein-1, and IFN-γ-secreting immune cells than tumors treated with cognate control oncolytic Ad expressing a single therapeutic gene (RdB/DCN or RdB/IL12). Moreover, RdB/IL12/DCN attenuated intratumoral TGF-β expression, which positively correlated with reduction of Treg cells in draining lymph nodes and tumor tissues. Furthermore, tumor tissue treated with RdB/IL12/DCN showed increases infiltration of CD8⁺ T cells and proficient viral spreading within tumor tissues. These results demonstrated that an oncolytic Ad co-expressing IL-12 and DCN induces a potent antitumor immune response via restoration of antitumor immune function in a weakly immunogenic murine 4T1 orthotopic breast cancer model. These findings provide new insights into the therapeutic mechanisms of IL-12 plus DCN, making it a promising cancer immunotherapeutic agent for overcoming tumor-induced immunosuppression.

MicroRNA-33a downregulation is associated with tumorigenesis and poor prognosis in patients with hepatocellular carcinoma

In order to examine the prognostic significance of miR-33a in patients with hepatocellular carcinoma (HCC), total RNA was extracted from 149 HCC biopsies, 36 of which were paired with para-carcinoma tissues, and miR-33a expression was measured by reverse transcription-quantitative polymerase chain reaction. The results demonstrated that miR-33a expression was decreased in HCC biopsies compared with normal liver tissue samples. It was also demonstrated that miR-33a expression was significantly associated with tumor foci number. Furthermore, overall and progression-free survival time was decreased in patients expressing low miR-33a with multiple tumor foci. Taken together, the low expression of miR-33a may be a potential risk factor for HCC.

Upregulation of microRNA-32 is associated with tumorigenesis and poor prognosis in patients with hepatocellular carcinoma

MicroRNA-32 (miR-32) is associated with tumor progression and poor prognosis in certain malignant tumors. However, the function and clinical relevance of miR-32 in human hepatocellular carcinoma (HCC) has not yet been elucidated. The present study aimed to investigate the expression and prognostic value of miR-32 from liver samples in patients with HCC. The expression of miR-32 was analyzed in HCC and healthy tissues using Gene Expression Omnibus datasets. Reverse transcription-quantitative polymerase chain reaction was used to analyze the levels of miR-32 mRNA in 154 HCC liver samples, 33 of which were paired with adjacent non-tumor tissues. The overall survival (OS) rate in patients with HCC was evaluated using Kaplan-Meier survival analysis, and the factors that may affect the prognosis and survival of patients with HCC were analyzed using univariate (log-rank test) and multivariate Cox proportional hazard models. The present results demonstrated that miR-32 expression levels were significantly upregulated in HCC liver biopsies compared with normal tissues (P<0.05). miR-32 expression was significantly associated with the number of foci and tumor diameter (P<0.05). In addition, Kaplan-Meier analysis revealed that patients with low miR-32 expression had longer OS and disease-free survival compared with those with high miR-32 expression (P<0.01). Altogether, to the best our knowledge, the present study is the first study to indicate the association between increased miR-32 expression with HCC progression and poor prognosis in patients. This suggests that miR-32 may have potential prognostic value and may be used as a tumor biomarker for the diagnosis of patients with HCC.

In Vivo Imaging Sheds Light on Immune Cell Migration and Function in Cancer

There is ample evidence for both beneficial and harmful involvement of the immune system in tumor development and spread. Immune cell recruitment to tumors is essential not only for the success of anticancer immune therapies but also for tumor-induced immune suppression. Now that immune-based therapies are playing an increasingly important role in treatment of solid tumors such as metastatic melanomas, precise analysis of the in vivo contributions of different leukocyte subsets in tumor immunity has become an even greater priority. Recently, this goal has been markedly facilitated by the use of intravital microscopy, which has enabled us to visualize the dynamic interactions between cells of the immune system and tumor targets in the context of the tumor microenvironment. For example, intravital imaging techniques have shed new light on T cell infiltration of tumors, the mechanisms of cancer cell killing, and how myeloid cells contribute to tumor tolerance and spread. This mini-review summarizes the recent advances made to our understanding of the roles of innate and adaptive immune cells in cancer based on the use of these in vivo imaging approaches.

Micro RNA-98 interferes with expression interleukin-10 in peripheral B cells of patients with lung cancer

Interleukin (IL)-10-producing B cells (B10 cells) plays an important role in the tumor tolerance. High frequency of peripheral B10 cell was reported in patients with lung cancer recently. Micro RNA (miR) regulates some gene expression. This study test a hypothesis that miR-98 suppresses the expression of IL-10 in B cells of subjects with lung cancer. The results showed that the levels of miR-98 were significantly less in peripheral B cells of patients with lung cancer than that in healthy subjects. IL-10 mRNA levels in peripheral B cells were significantly higher in lung cancer patients as compared with healthy controls. A negative correlation was identified between miR-98 and IL-10 in peripheral B cells. Serum IL-13 was higher in lung cancer patients than that in healthy controls. The levels of IL-13 were also negatively correlated with IL-10 in B cells. Exposure B10 cells to IL-13 in the culture or over expression of miR-98 reduced the expression of IL-10 in B cells. Administration with miR-98-laden liposomes inhibited the lung cancer growth in a mouse model. In conclusion, up regulation of miR-98 inhibits the expression of IL-10 in B cells, which may contribute to inhibit the lung cancer tolerance in the body.

Endometriosis-induced changes in regulatory T cells - insights towards developing permanent contraception

BACKGROUND

Endometriosis is a gynecological disorder that is associated with alterations in the immune system that contributes to its pathology as well as its associated infertility.

MAIN FINDINGS

This brief report summarizes our findings related to the changes in T regulatory cells (Tregs) that may affect the uterine environment and impact the fertility of women and nonhuman primates with endometriosis.

PRINCIPAL CONCLUSION

Targeted therapies that could reduce Tregs within the reproductive tract may have a potential as long-lasting or permanent contraception.

The effect of ionizing radiation on regulatory T cells in health and disease

Treg cells are key elements of the immune system which are responsible for the immune suppressive phenotype of cancer patients. Interaction of Treg cells with conventional anticancer therapies might fundamentally influence cancer therapy response rates. Radiotherapy, apart from its direct tumor cell killing potential, has a contradictory effect on the antitumor immune response: it augments certain immune parameters, while it depresses others. Treg cells are intrinsically radioresistant due to reduced apoptosis and increased proliferation, which leads to their systemic and/or intratumoral enrichment. While physiologically Treg suppression is not enhanced by irradiation, this is not the case in a tumorous environment, where Tregs acquire a highly suppressive phenotype, which is further increased by radiotherapy. This is the reason why the interest for combined radiotherapy and immunotherapy approaches focusing on the abrogation of Treg suppression has increased in cancer therapy in the last few years. Here we summarize the basic mechanisms of Treg radiation response both in healthy and cancerous environments and discuss Treg-targeted pre-clinical and clinical immunotherapy approaches used in combination with radiotherapy. Finally, the discrepant findings regarding the predictive value of Tregs in therapy response are also reviewed.

The effect of metronomic versus standard chemotherapy on the regulatory to effector T-cell equilibrium in cancer patients

BACKGROUND

The host's immune system is crucially involved in cancer development and progression. The ratio of regulatory to effector T-cells, as well as the interplay of T-cells with therapeutic agents, impact on cancer prognosis. The current study aimed to comparatively investigate the effect of metronomic and standard chemotherapy on the number and functionality of peripheral regulatory and effector T-cells in cancer patients.

METHODS

CD4+CD25+ regulatory and CD4+CD25- effector T-cells were purified from the peripheral blood of 36 cancer patients and co-cultured in the presence of a polyclonal stimulus. The proliferative capacity and frequency of CD4+CD25+/CD4+CD25- T-cells were analysed before and during various chemotherapeutic regimes, by ELISA and flow cytometry, respectively.

RESULTS

Chemotherapy shifted immune responses in favour of regulatory T-cells. The relative ratio of regulatory to effector T-cells increased, and the T-cell-mediated suppressive activity of regulatory on effector T-cells was augmented. This effect was more profound in metronomic than in standard chemotherapeutic approaches. Moreover, an association between the chemotherapy strategy followed and the mode of action of specific drugs (anti-mitotic, anti-DNA) was revealed.

CONCLUSIONS

In comparison to standard chemotherapeutic strategies, metronomic approaches, though more patient-friendly, result in a significantly more prominent expansion of regulatory T-cells that aggravate the regulatory to effector T-cell imbalance. Our findings impact on the modulation of chemotherapy-treated patients' anti-tumor immunity and, thus, may be proven useful for selecting the most advantageous drug-delivery strategy, particularly when immunotherapeutics are eventually to be applied.

Twist and miR-34a are involved in the generation of tumor-educated myeloid-derived suppressor cells

Tumors can induce the generation and accumulation of immunosuppressive cells such as myeloid-derived suppressor cells in the tumor microenvironment, contributing to tumor immunological escapes. Many studies have demonstrated that multiple factors could induce myeloid precursor cells into myeloid-derived suppressor cells, not dendritic cells. In our study, we found that tumor supernatants could induce the generation of myeloid-derived suppressor cells by disturbing the development of dendritic cells. Twist and miR-34a may regulate the effect of tumor cells inducing myeloid-derived suppressor cells via TGF-β and/or IL-10.

The role played by the microenvironment in site-specific metastasis

Cancer cells that disseminate to metastatic sites may progress to frank metastasis or persist as dormant micrometastasis. Significant progress has been made in defining the genetic and phenotypic cancer-cell-autonomous determinants of metastasis and in the understanding of the cross-talk between metastasizing tumor cells and the metastatic microenvironment. However several questions remain open, in particular the identity of microenvironmental factors that keep micrometastatic cells in a state of dormancy and those that promote survival, proliferation and progression of such cells. Significantly more information is available on the latter factors than on microenvironmental cells and molecules that restrain micrometastasis. This mini-review summarizes findings suggesting that: In view of the above, it is not unlikely that metastases residing in different microenvironments may require "individualized" treatment modalities.

Intratumor hypoxia promotes immune tolerance by inducing regulatory T cells via TGF-β1 in gastric cancer

Regulatory T cell (Treg)-mediated immunosuppression represents one of the crucial tumor immune evasion mechanisms and is a main obstacle for successful tumor immunotherapy. Hypoxia, a common feature of solid tumors, has been associated with potentiated immunosuppression, decreased therapeutic response, malignant progression and local invasion. Unfortunately, the link between hypoxia and Treg-mediated immune tolerance in gastric cancer remains poorly understood. In our study, Tregs and hypoxia inducible factor-1α were found to be positively correlated with each other and were increased with the tumor progression. A subsequent in vitro study indicated that supernatants derived from gastric cancer cells under hypoxic condition, could induce the expression of Foxp3 via TGF-β1. These findings confirmed the crucial role of Tregs as a therapeutic target in gastric cancer therapy and provided helpful thoughts for the design of immunotherapy for gastric cancer in the future.