Tumor and its microenvironment: a synergistic interplay

TGFβ Signaling in the Tumor Microenvironment

Transforming growth factor beta (TGFβ) is a pleiotropic growth factor. Under normal physiological conditions, TGFβ maintains homeostasis in mammalian tissues by restraining the growth of cells and stimulating apoptosis. However, the role of TGFβ signaling in the carcinogenesis is complex. TGFβ acts as a tumor suppressor in the early stages of disease and as a tumor promoter in its later stages where cancer cells have been relieved from TGFβ growth controls. Overproduction of TGFβ by cancer cells lead to a local fibrotic and immune-suppressive microenvironment that fosters tumor growth and correlates with invasive and metastatic behavior of the cancer cells. Here, we present an overview of the complex biology of the TGFβ family, and we discuss the roles of TGFβ signaling in carcinogenesis and how this knowledge is being leveraged to develop TGFβ inhibition therapies against the tumor.

Extracellular Vesicles Orchestrate Immune and Tumor Interaction Networks

Simple Summary

Significant strides have been made to describe the pervasive role of extracellular vesicles (EVs) in health and disease. This work provides an insightful and unifying mechanistic understanding of EVs in immunity and tumorigenesis. This is achieved by dissecting the role of EVs within the continuum of immune cell physiology, immune–infection responses, and the immune–tumor microenvironment. Our work synthesizes important topical findings on immune EV signaling in mediating immune–tumor interaction networks.

Abstract

Extracellular vesicles (EVs) are emerging as potent and intricate intercellular communication networks. From their first discovery almost forty years ago, several studies have bolstered our understanding of these nano-vesicular structures. EV subpopulations are now characterized by differences in size, surface markers, cargo, and biological effects. Studies have highlighted the importance of EVs in biology and intercellular communication, particularly during immune and tumor interactions. These responses can be equally mediated at the proteomic and epigenomic levels through surface markers or nucleic acid cargo signaling, respectively. Following the exponential growth of EV studies in recent years, we herein synthesize new aspects of the emerging immune–tumor EV-based intercellular communications. We also discuss the potential role of EVs in fundamental immunological processes under physiological conditions, viral infections, and tumorigenic conditions. Finally, we provide insights on the future prospects of immune–tumor EVs and suggest potential avenues for the use of EVs in diagnostics and therapeutics.

Angiogenesis-Related Functions of Wnt Signaling in Colorectal Carcinogenesis

Simple Summary

Angiogenesis belongs to the most clinical characteristics of colorectal cancer (CRC) and is strongly linked to the activation of Wnt/β-catenin signaling. The most prominent factors stimulating constitutive activation of this pathway, and in consequence angiogenesis, are genetic alterations (mainly mutations) concerning APC and the β-catenin encoding gene (CTNNB1), detected in a large majority of CRC patients. Wnt/β-catenin signaling is involved in the basic types of vascularization (sprouting and nonsprouting angiogenesis), vasculogenic mimicry as well as the formation of mosaic vessels. The number of known Wnt/β-catenin signaling components and other pathways interacting with Wnt signaling, regulating angiogenesis, and enabling CRC progression continuously increases. This review summarizes the current knowledge about the role of the Wnt/Fzd/β-catenin signaling pathway in the process of CRC angiogenesis, aiming to improve the understanding of the mechanisms of metastasis as well as improvements in the management of this cancer.

Abstract

Aberrant activation of the Wnt/Fzd/β-catenin signaling pathway is one of the major molecular mechanisms of colorectal cancer (CRC) development and progression. On the other hand, one of the most common clinical CRC characteristics include high levels of angiogenesis, which is a key event in cancer cell dissemination and distant metastasis. The canonical Wnt/β-catenin downstream signaling regulates the most important pro-angiogenic molecules including vascular endothelial growth factor (VEGF) family members, matrix metalloproteinases (MMPs), and chemokines. Furthermore, mutations of the β-catenin gene associated with nuclear localization of the protein have been mainly detected in microsatellite unstable CRC. Elevated nuclear β-catenin increases the expression of many genes involved in tumor angiogenesis. Factors regulating angiogenesis with the participation of Wnt/β-catenin signaling include different groups of biologically active molecules including Wnt pathway components (e.g., Wnt2, DKK, BCL9 proteins), and non-Wnt pathway factors (e.g., chemoattractant cytokines, enzymatic proteins, and bioactive compounds of plants). Several lines of evidence argue for the use of angiogenesis inhibition in the treatment of CRC. In the context of this paper, components of the Wnt pathway are among the most promising targets for CRC therapy. This review summarizes the current knowledge about the role of the Wnt/Fzd/β-catenin signaling pathway in the process of CRC angiogenesis, aiming to improve the understanding of the mechanisms of metastasis as well as improvements in the management of this cancer.

High Adenosine Extracellular Levels Induce Glioblastoma Aggressive Traits Modulating the Mesenchymal Stromal Cell Secretome

Glioblastoma is an aggressive, fast-growing brain tumor influenced by the composition of the tumor microenvironment (TME) in which mesenchymal stromal cell (MSCs) play a pivotal role. Adenosine (ADO), a purinergic signal molecule, can reach up to high micromolar concentrations in TME. The activity of specific adenosine receptor subtypes on glioma cells has been widely explored, as have the effects of MSCs on tumor progression. However, the effects of high levels of ADO on glioma aggressive traits are still unclear as is its role in cancer cells-MSC cross-talk. Herein, we first studied the role of extracellular Adenosine (ADO) on isolated human U343MG cells as a glioblastoma cellular model, finding that at high concentrations it was able to prompt the gene expression of Snail and ZEB1, which regulate the epithelial-mesenchymal transition (EMT) process, even if a complete transition was not reached. These effects were mediated by the induction of ERK1/2 phosphorylation. Additionally, ADO affected isolated bone marrow derived MSCs (BM-MSCs) by modifying the pattern of secreted inflammatory cytokines. Then, the conditioned medium (CM) of BM-MSCs stimulated with ADO and a co-culture system were used to investigate the role of extracellular ADO in GBM-MSC cross-talk. The CM promoted the increase of glioma motility and induced a partial phenotypic change of glioblastoma cells. These effects were maintained when U343MG cells and BM-MSCs were co-cultured. In conclusion, ADO may affect glioma biology directly and through the modulation of the paracrine factors released by MSCs overall promoting a more aggressive phenotype. These results point out the importance to deeply investigate the role of extracellular soluble factors in the glioma cross-talk with other cell types of the TME to better understand its pathological mechanisms.

Hypoxia Induces Mitochondrial Defect That Promotes T Cell Exhaustion in Tumor Microenvironment Through MYC-Regulated Pathways

T cell exhaustion is an obstacle to immunotherapy for solid tumors. An understanding of the mechanism by which T cells develop this phenotype in solid tumors is needed. Here, hypoxia, a feature of the tumor microenvironment, causes T cell exhaustion (T_Exh) by inducing a mitochondrial defect. Upon exposure to hypoxia, activated T cells with a T_Exh phenotype are characterized by mitochondrial fragmentation, decreased ATP production, and decreased mitochondrial oxidative phosphorylation activity. The T_Exh phenotype is correlated with the downregulation of the mitochondrial fusion protein mitofusin 1 (MFN1) and upregulation of miR-24. Overexpression of miR-24 alters the transcription of many metabolism-related genes including its target genes MYC and fibroblast growth factor 11 (FGF11). Downregulation of MYC and FGF11 induces T_Exh differentiation, reduced ATP production and a loss of the mitochondrial mass in T cell receptor (TCR)-stimulated T cells. In addition, we determined that MYC regulates the transcription of FGF11 and MFN1. In nasopharyngeal carcinoma (NPC) tissues, the T cells exhibit an increased frequency of exhaustion and loss of mitochondrial mass. In addition, inhibition of miR-24 signaling decreases NPC xenograft growth in nude mice. Our findings reveal a mechanism for T cell exhaustion in the tumor environment and provide potential strategies that target mitochondrial metabolism for cancer immunotherapy.

MicroRNA‑137 exerts protective effects on hypoxia‑induced cell injury by inhibiting autophagy/mitophagy and maintaining mitochondrial function in breast cancer stem‑like cells

Breast cancer stem‑like cells (BCSCs) have been identified and proven to play critical roles in tumorigenesis and progression. Hypoxia is a common pathologic feature of breast cancer and potentially, at least in part, regulates the initiation, progression, and recurrence of breast cancer. However, less is known about how hypoxia regulates BCSCs. As several well‑known microRNAs respond to hypoxia, we aimed to determine how hypoxia regulates the physiological processes of BCSCs by regulating the corresponding microRNAs. As expected, microRNA‑137 (miRNA‑137 or miR‑137) was downregulated upon hypoxic exposure, indicating that it may play critical roles in BCSCs. Introduction of miR‑137 mimics promoted cell cycle entry and inhibited hypoxia‑induced cell apoptosis as determined by cell cycle assay and apoptosis assay. By detecting mitochondrial reactive oxygen species (ROS), it was found that miR‑137 inhibited ROS accumulation induced by hypoxic exposure and thus suppressed cell apoptosis. Introduction of miR‑137 mimics under hypoxia inhibited mitophagy/autophagy by targeting FUN14 domain containing 1 (Fundc1) and thus promoted mitochondrial functions, including mitochondrial mass, ATP synthesis and mitochondrial transcriptional activity, which was similar to the effects of Fundc1 knockdown by specific siRNA. Based on these observations, we hypothesized that the survival of BCSCs under hypoxia was mediated by miR‑137 by regulating mitochondrial dysfunction. We demonstrated here that the introduction of exogenous miR‑137 promoted mitochondrial function, indicating that it may be a potential therapeutic target in BCSCs.

Eco-oncology: Applying ecological principles to understand and manage cancer

Cancer is a disease of single cells that expresses itself at the population level. The striking similarities between initiation and growth of tumors and dynamics of biological populations, and between metastasis and ecological invasion and community dynamics suggest that oncology can benefit from an ecological perspective to improve our understanding of cancer biology. Tumors can be viewed as complex, adaptive, and evolving systems as they are spatially and temporally heterogeneous, continually interacting with each other and with the microenvironment and evolving to increase the fitness of the cancer cells. We argue that an eco-evolutionary perspective is essential to understand cancer biology better. Furthermore, we suggest that ecologically informed therapeutic approaches that combine standard of care treatments with strategies aimed at decreasing the evolutionary potential and fitness of neoplastic cells, such as disrupting cell-to-cell communication and cooperation, and preventing successful colonization of distant organs by migrating cancer cells, may be effective in managing cancer as a chronic condition.

Targeting the Tumor Microenvironment in Neuroblastoma: Recent Advances and Future Directions

Neuroblastoma (NB) is the most common pediatric tumor malignancy that originates from the neural crest and accounts for more than 15% of all the childhood deaths from cancer. The neuroblastoma cancer research has long been focused on the role of MYCN oncogene amplification and the contribution of other genetic alterations in the progression of this malignancy. However, it is now widely accepted that, not only tumor cells, but the components of tumor microenvironment (TME), including extracellular matrix, stromal cells and immune cells, also contribute to tumor progression in neuroblastoma. The complexity of different components of tumor stroma and their resemblance with surrounding normal tissues pose huge challenges for therapies targeting tumor microenvironment in NB. Hence, the detailed understanding of the composition of the TME of NB is crucial to improve existing and future potential immunotherapeutic approaches against this childhood cancer. In this review article, I will discuss different components of the TME of NB and the recent advances in the strategies, which are used to target the tumor microenvironment in neuroblastoma.

Tumor microenvironment-oriented adaptive nanodrugs based on peptide self-assembly

The aberrant metabolism of tumor cells creates an inimitable microenvironment featuring acidic pH, high glutathione (GSH) levels, and overexpression of certain enzymes, which benefits the overwhelming progress of a tumor. Peptide self-assembly, emerging as a biofriendly and versatile fabrication strategy, harnesses multiple noncovalent interactions to obtain a variety of nanostructures tailored on demand. Orchestrating the reversible nature of noncovalent interactions and abnormal physiological parameters in the tumor microenvironment enables peptide-based nanodrugs to be targetable or switchable, thereby improving the drugs' bioavailability and optimizing the treatment outcome. This review will focus on peptide-modulated self-assembly of photosensitizers, chemotherapeutic drugs, immunoactive agents for tumor microenvironment-oriented adaptive phototherapy, chemotherapy, immunotherapy and combinatorial therapy. We will emphasize the building block design, the intermolecular interaction principle, adaptive structural transformation in the tumor microenvironment and corresponding therapeutic efficacy, and aim to elucidate the critical role of peptide-modulated, tumor microenvironment-oriented adaptive assemblies in improving the therapeutic index. Challenges and opportunities will be covered as well to advance the development and clinical application of tumor therapies based on peptide self-assembly materials and techniques.

Modifying the tumour microenvironment and reverting tumour cells: New strategies for treating malignant tumours

The tumour microenvironment (TME) plays a pivotal role in tumour fate determination. The TME acts together with the genetic material of tumour cells to determine their initiation, metastasis and drug resistance. Stromal cells in the TME promote the growth and metastasis of tumour cells by secreting soluble molecules or exosomes. The abnormal microenvironment reduces immune surveillance and tumour killing. The TME causes low anti‐tumour drug penetration and reactivity and high drug resistance. Tumour angiogenesis and microenvironmental hypoxia limit the drug concentration within the TME and enhance the stemness of tumour cells. Therefore, modifying the TME to effectively attack tumour cells could represent a comprehensive and effective anti‐tumour strategy. Normal cells, such as stem cells and immune cells, can penetrate and disrupt the abnormal TME. Reconstruction of the TME with healthy cells is an exciting new direction for tumour treatment. We will elaborate on the mechanism of the TME to support tumours and the current cell therapies for targeting tumours and the TME—such as immune cell therapies, haematopoietic stem cell (HSC) transplantation therapies, mesenchymal stem cell (MSC) transfer and embryonic stem cell‐based microenvironment therapies—to provide novel ideas for producing breakthroughs in tumour therapy strategies.

Simulating the human colorectal cancer microenvironment in 3D tumor-stroma co-cultures in vitro and in vivo

The tumor microenvironment (TME) plays a significant role in cancer progression and thus modeling it will advance our understanding of cancer growth dynamics and response to therapies. Most in vitro models are not exposed to intact body physiology, and at the same time, fail to recapitulate the extensive features of the tumor stroma. Conversely, animal models do not accurately capture the human tumor architecture. We address these deficiencies with biofabricated colorectal cancer (CRC) tissue equivalents, which are built to replicate architectural features of biopsied CRC tissue. Our data shows that tumor-stroma co-cultures consisting of aligned extracellular matrix (ECM) fibers and ordered micro-architecture induced an epithelial phenotype in CRC cells while disordered ECM drove a mesenchymal phenotype, similar to well and poorly differentiated tumors, respectively. Importantly, co-cultures studied in vitro, and upon implantation in mice, revealed similar tumor growth dynamics and retention of architectural features for 28 days. Altogether, these results are the first demonstration of replicating human tumor ECM architecture in ex vivo and in vivo cultures.

Epithelial-mesenchymal transition and metastasis of colon cancer cells induced by the FAK pathway in cancer-associated fibroblasts

OBJECTIVE

The role and mechanism of tetrathiomolybdate (TM) in cancer-associated fibroblasts (CAFs) in colon cancer using three-dimensional (3D) culture were investigated, and the associations between the focal adhesion kinase (FAK) pathway and epithelial-mesenchymal transition (EMT) in CAFs were explored.

METHODS

A 3D co-culture model of colon cancer LOVO cells with CAFs and normal fibroblasts (NFs) was established using Matrigel as a scaffold material. The differential expression of LOXL2 (lysyl oxidase-like 2) in the supernatant of CAFs and NFs was determined using ELISA, and expression levels of EMT-related proteins and FAK signaling pathway-related proteins were determined using western blot.

RESULTS

LOXL2 levels secreted by CAFs were higher compared with that secreted by NFs. In the CAF + LOVO group, compared with the LOVO group, E-cadherin expression decreased significantly, while N-cadherin and F-PAK expression increased significantly. TM results were opposite compared with the above results.

CONCLUSIONS

CAFs stimulate EMT in human colon cancer LOVO cells by secreting LOXL2 to activate the FAK signaling pathway, thereby promoting tumor metastasis. TM inhibited the occurrence of EMT in the CAF-induced colon cancer LOVO cell line, thereby reducing the invasion and metastasis of colon cancer cells.

Exosomes derived from normal human bronchial epithelial cells down-regulate proliferation and migration of hydroquinone-transformed malignant recipient cells via up-regulating PTEN expression

The gene encoding the tumor suppressor, phosphatase and tensin homolog (PTEN), located on chromosome 10, is frequently expressed at low levels in various tumors, resulting in the stimulation of cell proliferation and migration. However, the role of exosomal PTEN in cell-cell communication during the progress of benzene-induced carcinogenesis remains unclear. The goal of this study was to explore whether exosomes derived from normal human bronchial epithelial cells (16HBE) could transmit PTEN to hydroquinone-transformed malignant recipient cells (16HBE-t) and its possible effects on cell proliferation and migration. Consistent with PTEN expression being down-regulated in transformed cells, we found that its expression was significantly decreased in 16HBE-t relative to 16HBE cells and that purified exosomes secreted by 16HBE, up-regulated PTEN levels in recipient 16HBE-t cells. Thus, down-regulating their proliferation and migration. Further, when exosomes derived from 16HBE cells that had been treated with the PTEN inhibitor SF1670, were incubated with recipient 16HBE-t cells, they exhibited decreased PTEN levels, with a corresponding increase in their proliferation and migration. In conclusion, our study demonstrates that exosomes derived from 16HBE cells can down-regulate proliferation and migration of recipient 16HBE-t cells via transferring PTEN.

Changes in extracellular matrix in different stages of colorectal cancer and their effects on proliferation of cancer cells

BACKGROUND

The extracellular matrix is the main component of the tumor microenvironment. Extracellular matrix remodels with the oncogenesis and development of tumors. Previous studies usually focused on the changes of proteins in normal colorectal tissues and colorectal cancers. Little is known about the changes in the extracellular matrix in different stages of colorectal cancer and the effects of these changes on the development of this cancer.

AIM

To test the changes of type I collagen, type IV collagen, matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of metalloproteinase-3 (TIMP-3) in different stages of colorectal cancer and the effects of these changes on the proliferation of cancer cells.

METHODS

The extracellular matrix from various stages of colorectal cancer and normal colon tissue was obtained by using acellular technology. We used proteomics to detect the differential expression of proteins between normal colon tissues and colorectal cancer tissues, and then we used Western blot to observe their expression in each stage of colorectal cancer and in normal colon tissue. By co-culturing the extracellular matrix and HT29 colon cancer cells in vivo and in vitro, we tested the cancer cell proliferation rate in vitro by methyl thiazolyl tetrazolium (MTT) assay and in vivo by measuring the tumor volume.

RESULTS

The expression of type I collagen and MMP-2 increased with increased tumor stage. The expression of MMP-9 was higher in colorectal cancer tissues and was highest in stage III cancer. The expression of type IV collagen and TIMP-3 decreased with increased tumor stage. The proliferation rate of cancer cells in the extracellular matrix of colorectal cancer was higher than that in the extracellular matrix of the normal colon.

CONCLUSION

These data suggest that the extracellular matrix structure and composition become disorganized during the development of tumors, which is more conducive for the growth of cancer cells.

Inactivation of endothelial ZEB1 impedes tumor progression and sensitizes tumors to conventional therapies

Current antiangiogenic therapy is limited by its cytostatic property, scarce drug delivery to the tumor, and side toxicity. To address these limitations, we unveiled the role of ZEB1, a tumor endothelium-enriched zinc-finger transcription factor, during tumor progression. We discovered that the patients who had lung adenocarcinomas with high ZEB1 expression in tumor endothelium had increased prevalence of metastases and markedly reduced overall survival after the diagnosis of lung cancer. Endothelial ZEB1 deletion in tumor-bearing mice diminished tumor angiogenesis while eliciting persistent tumor vascular normalization by epigenetically repressing TGF-β signaling. This consequently led to improved blood and oxygen perfusion, enhanced chemotherapy delivery and immune effector cell infiltration, and reduced tumor growth and metastasis. Moreover, targeting vascular ZEB1 remarkably potentiated the anticancer activity of nontoxic low-dose cisplatin. Treatment with low-dose anti-programmed cell death protein 1 (anti-PD-1) antibody elicited tumor regression and markedly extended survival in ZEB1-deleted mice, conferring long-term protective anticancer immunity. Collectively, we demonstrated that inactivation of endothelial ZEB1 may offer alternative opportunities for cancer therapy with minimal side effects. Targeting endothelium-derived ZEB1 in combination with conventional chemotherapy or immune checkpoint blockade therapy may yield a potent and superior anticancer effect.

Recent Advances in Microfluidic Platforms Applied in Cancer Metastasis: Circulating Tumor Cells' (CTCs) Isolation and Tumor-On-A-Chip

Cancer remains the leading cause of death worldwide despite the enormous efforts that are made in the development of cancer biology and anticancer therapeutic treatment. Furthermore, recent studies in oncology have focused on the complex cancer metastatic process as metastatic disease contributes to more than 90% of tumor-related death. In the metastatic process, isolation and analysis of circulating tumor cells (CTCs) play a vital role in diagnosis and prognosis of cancer patients at an early stage. To obtain relevant information on cancer metastasis and progression from CTCs, reliable approaches are required for CTC detection and isolation. Additionally, experimental platforms mimicking the tumor microenvironment in vitro give a better understanding of the metastatic microenvironment and antimetastatic drugs' screening. With the advancement of microfabrication and rapid prototyping, microfluidic techniques are now increasingly being exploited to study cancer metastasis as they allow precise control of fluids in small volume and rapid sample processing at relatively low cost and with high sensitivity. Recent advancements in microfluidic platforms utilized in various methods for CTCs' isolation and tumor models recapitulating the metastatic microenvironment (tumor-on-a-chip) are comprehensively reviewed. Future perspectives on microfluidics for cancer metastasis are proposed.

Exosomes are the Driving Force in Preparing the Soil for the Metastatic Seeds: Lessons from the Prostate Cancer

Exosomes are nano-membrane vesicles that various cell types secrete during physiological and pathophysiological conditions. By shuttling bioactive molecules such as nucleic acids, proteins, and lipids to target cells, exosomes serve as key regulators for multiple cellular processes, including cancer metastasis. Recently, microvesicles have emerged as a challenge in the treatment of prostate cancer (PCa), encountered either when the number of vesicles increases or when the vesicles move into circulation, potentially with an ability to induce drug resistance, angiogenesis, and metastasis. Notably, the exosomal cargo can induce the desmoplastic response of PCa-associated cells in a tumor microenvironment (TME) to promote PCa metastasis. However, the crosstalk between PCa-derived exosomes and the TME remains only partially understood. In this review, we provide new insights into the metabolic and molecular signatures of PCa-associated exosomes in reprogramming the TME, and the subsequent promotion of aggressive phenotypes of PCa cells. Elucidating the molecular mechanisms of TME reprogramming by exosomes draws more practical and universal conclusions for the development of new therapeutic interventions when considering TME in the treatment of PCa patients.

Nuclear-localized costimulatory molecule 4-1BBL promotes colon cancer cell proliferation and migration by regulating nuclear Gsk3β, and is linked to the poor outcomes associated with colon cancer

Anti-tumor immune response and the prognosis of tumor are the results of competition between stimulatory and inhibitory checkpoints. Except for upregulating inhibitory checkpoints, lowering some immune accelerating molecules to convert an immunostimulatory microenvironment into an immunodormant one through "decelerating the accelerator" might be another effective immune escape pattern. 4-1BBL is a classical transmembrane costimulatory molecule involving in antitumor immune responses. In contrast, we demonstrated that 4-1BBL is predominantly localized in the nuclei of cancer cells in colon cancer specimens and is positively correlated with tumor size, lymph node metastasis, and a lower survival ratio. Furthermore, the nuclear localization of 4-1BBL was also ascertained in vitro. 4-1BBL knockout (KO) arrests the proliferation and impaired the migration and invasion ability of colon cancer cells in vitro and retarded tumor growth in vivo. 4-1BBL KO increased the accumulation of Gsk3β in the nuclei of colon cancer cells and consequently decreased the expression of Wnt pathway target genes and thus alter tumor biological behavior. We hypothesized that unlike membrane-expressed 4-1BBL, which stimulates the 4-1BB signaling of antitumor cytotoxic T cells, the nuclear-localized 4-1BBL could facilitate the malignant behavior of colon cancer cells by circumventing antitumor signaling and driving some key oncotropic signal pathway in the nucleus. Nuclear-localized 4-1BBL might be an indicator of colon cancer malignancy and serve as a promising target of immunotherapy.

Construction of a risk score prognosis model based on hepatocellular carcinoma microenvironment

BACKGROUND

Hepatocellular carcinoma (HCC) is a common cancer with a poor prognosis. Previous studies revealed that the tumor microenvironment (TME) plays an important role in HCC progression, recurrence, and metastasis, leading to poor prognosis. However, the effects of genes involved in TME on the prognosis of HCC patients remain unclear. Here, we investigated the HCC microenvironment to identify prognostic genes for HCC.

AIM

To identify a robust gene signature associated with the HCC microenvironment to improve prognosis prediction of HCC.

METHODS

We computed the immune/stromal scores of HCC patients obtained from The Cancer Genome Atlas based on the ESTIMATE algorithm. Additionally, a risk score model was established based on Differentially Expressed Genes (DEGs) between high‐ and low‐immune/stromal score patients.

RESULTS

The risk score model consisting of eight genes was constructed and validated in the HCC patients. The patients were divided into high- or low-risk groups. The genes (Disabled homolog 2, Musculin, C-X-C motif chemokine ligand 8, Galectin 3, B-cell-activating transcription factor, Killer cell lectin like receptor B1, Endoglin and adenomatosis polyposis coli tumor suppressor) involved in our risk score model were considered to be potential immunotherapy targets, and they may provide better performance in combination. Functional enrichment analysis showed that the immune response and T cell receptor signaling pathway represented the major function and pathway, respectively, related to the immune-related genes in the DEGs between high- and low-risk groups. The receiver operating characteristic (ROC) curve analysis confirmed the good potency of the risk score prognostic model. Moreover, we validated the risk score model using the International Cancer Genome Consortium and the Gene Expression Omnibus database. A nomogram was established to predict the overall survival of HCC patients.

CONCLUSION

The risk score model and the nomogram will benefit HCC patients through personalized immunotherapy.

Microenvironment in Cardiac Tumor Development: What Lies Beyond the Event Horizon?

Cardiac tumors are found in less than 1% of adult and pediatric autopsies. More than three-fourths of primary cardiac neoplasms are benign, with myxomas and rhabdomyomas being the most common cardiac tumors seen in adults and children, respectively. Primary malignant cardiac tumors are extremely rare, whereas metastatic lesions can be seen in approximately 8% of patients dying from cancer. Attempting to understand why the heart is so resistant to carcinogenesis and which fail-safe mechanisms malfunction when cardiac tumors do develop is particularly challenging considering the rarity of these tumors and the fact that when relevant clinical studies are published, they rarely focus on molecular pathogenesis. Apart from cancer cells, solid tumors are comprised of a concoction of noncancerous cells, and extracellular matrix constituents, which along with pH and oxygen levels jointly constitute the so-called tumor microenvironment (TME). In the present chapter, we explore mechanisms through which TME may influence cardiac carcinogenesis.

Reductive Activity and Mechanism of Hypoxia- Targeted AGT Inhibitors: An Experimental and Theoretical Investigation

O6-alkylguanine-DNA alkyltransferase (AGT) is the main cause of tumor cell resistance to DNA-alkylating agents, so it is valuable to design tumor-targeted AGT inhibitors with hypoxia activation. Based on the existing benchmark inhibitor O6-benzylguanine (O6-BG), four derivatives with hypoxia-reduced potential and their corresponding reduction products were synthesized. A reductase system consisting of glucose/glucose oxidase, xanthine/xanthine oxidase, and catalase were constructed, and the reduction products of the hypoxia-activated prodrugs under normoxic and hypoxic conditions were determined by high-performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). The results showed that the reduction products produced under hypoxic conditions were significantly higher than that under normoxic condition. The amount of the reduction product yielded from ANBP (2-nitro-6-(3-amino) benzyloxypurine) under hypoxic conditions was the highest, followed by AMNBP (2-nitro-6-(3-aminomethyl)benzyloxypurine), 2-NBP (2-nitro-6-benzyloxypurine), and 3-NBG (O6-(3-nitro)benzylguanine). It should be noted that although the levels of the reduction products of 2-NBP and 3-NBG were lower than those of ANBP and AMNBP, their maximal hypoxic/normoxic ratios were higher than those of the other two prodrugs. Meanwhile, we also investigated the single electron reduction mechanism of the hypoxia-activated prodrugs using density functional theory (DFT) calculations. As a result, the reduction of the nitro group to the nitroso was proven to be a rate-limiting step. Moreover, the 2-nitro group of purine ring was more ready to be reduced than the 3-nitro group of benzyl. The energy barriers of the rate-limiting steps were 34-37 kcal/mol. The interactions between these prodrugs and nitroreductase were explored via molecular docking study, and ANBP was observed to have the highest affinity to nitroreductase, followed by AMNBP, 2-NBP, and 3-NBG. Interestingly, the theoretical results were generally in a good agreement with the experimental results. Finally, molecular docking and molecular dynamics simulations were performed to predict the AGT-inhibitory activity of the four prodrugs and their reduction products. In summary, simultaneous consideration of reduction potential and hypoxic selectivity is necessary to ensure that such prodrugs have good hypoxic tumor targeting. This study provides insights into the hypoxia-activated mechanism of nitro-substituted prodrugs as AGT inhibitors, which may contribute to reasonable design and development of novel tumor-targeted AGT inhibitors.

A Hierarchical Peptide-Lanthanide Framework To Accurately Redress Intracellular Carcinogenic Protein-Protein Interaction

Intracellular protein-protein interactions (PPIs) are a vital and yet underexploited class of therapeutic targets for their crucial roles in cellular processes and involvement in disease initiation and progression. Although some successful chemistry and nanotechnologies have been introduced into peptide PPI modulators to allow cell and tissue permeability, significant challenges remain with regard to the efficient and precise modulation of PPIs within specific cells of diseased tissues, such as solid tumors. Herein, an intratumoral transformable hierarchical framework, termed iPLF, was fabricated via a two-step self-assembly between peptides and lanthanide-doped nanocrystals. In this proof-of-concept study, using NanoEL effect, TME response, and tumor marker targeting, iPLF in vivo delivered the p53-MDM2 modulator DPMI into tumor cells and β-catenin-Bcl9 modulator Bcl9p into tumor stem cells. This crafted programmed nanomedicine with triple-stage delivery and responsiveness accurately modulated the specific intracellular protein-protein interactions, resulting in the suppression of tumor growth and metastasis in vivo, while maintaining a highly favorable safety profile. iPLF reached the goal of accurate, potent, and hazard-free intracellular PPI modulation, thereby providing a means to improve current knowledge of PPI networks and a novel therapeutic strategy for a great variety of diseases.

Relationships between hypoxia induced factor-1α and 18F-FDG PET/CT parameters in colorectal cancer

AIM

The hypoxia-inducible factor 1 (HIF-1) has a critical role in oxygen homeostasis and it is a transcriptional activator of angiogenesis, erythropoiesis, iron and glucose metabolism. Glucose metabolism rate is increased in some tumours via HIF-1α. Our aim is to evaluate the relationship between hypoxia in colorectal cancer, PET parameters, necrotic tissue size and pathologic prognostic factors via using HIF-1α.

MATERIALS/METHODS

70 patients (28 female/42 male; median age: 63 years) who were diagnosed with colorectal cancer via biopsy were staged with preoperative PET/CT and operated subsequently. Immunohistochemical evaluation scoring was done according to nuclear HIF-1α expression, staining density and intensity. Metabolic tumour volume (MTV), total lesion glycolysis (TLG) and tumour volume (TV) were calculated by using volume of an ellipsoid formula via CT images, and percentage of tumour necrosis (%TmNcr) that was calculated by the difference between TV and recorded MTV.

RESULTS

There was a moderately meaningful positive correlation between tumour SUVmax and TV and %TmNcr (r=0.403, p=0.001 and r=0.500, p=0.0001, respectively). There were no statistically significant relationships between HIF-1α expression levels and tumour SUVmax, TLG, MTV, TV, %TmNcr, tumour stage, lymphovascular invasion, perineural invasion and extracapsular/capsular lymph node involvement. On the other hand, strong nuclear immunohistochemical staining was seen in tumour cells adjacent to invasive border, inflammatory cells. Although not statistically significant, moderate or strong nuclear staining were seen in 64.9% of metastatic patients.

CONCLUSION

Although the presence of a positive correlation between tumour SUVmax and %TmNcr shows that there are hypoxic cells in cancer tissue with high FDG uptake, the relationship between the presence of HIF-1α and enhanced glucose metabolism and pathological prognostic factors of tumour was not shown. Strong nuclear immunohistochemical staining in tumour cells adjacent to invasive border and inflammatory cells leads us to believe that HIF-1α plays a role in the invasion area of tumour microenvironment.

Tumor cells hijack enteric glia to activate colon cancer stem cells and stimulate tumorigenesis

BACKGROUND

Colon cancer stem cells (CSCs), considered responsible for tumor initiation and cancer relapse, are constantly exposed to regulatory cues emanating from neighboring cells present in the tumor microenvironment. Among these cells are enteric glial cells (EGCs) that are potent regulators of the epithelium functions in a healthy intestine. However, whether EGCs impact CSC-driven tumorigenesis remains unknown.

METHODS

Impact of human EGC primary cultures or a non-transformed EGC line on CSCs isolated from human primary colon adenocarcinomas or colon cancer cell lines with different p53, MMR system and stemness status was determined using murine xenograft models and 3D co-culture systems. Supernatants of patient-matched human primary colon adenocarcinomas and non-adjacent healthy mucosa were used to mimic tumor versus healthy mucosa secretomes and compare their effects on EGCs.

FINDINGS

Our data show that EGCs stimulate CSC expansion and ability to give rise to tumors via paracrine signaling. Importantly, only EGCs that were pre-activated by tumor epithelial cell-derived soluble factors increased CSC tumorigenicity. Pharmacological inhibition of PGE2 biosynthesis in EGCs or IL-1 knockdown in tumor epithelial cells prevented EGC acquisition of a pro-tumorigenic phenotype. Inhibition of PGE2 receptor EP4 and EGFR in CSCs inhibited the effects of tumor-activated EGCs.

INTERPRETATION

Altogether, our results show that EGCs, once activated by the tumor, acquire a pro-tumorigenic phenotype and stimulate CSC-driven tumorigenesis via a PGE2/EP4/EGFR-dependent pathway.

FUNDING

This work was supported by grants from the French National Cancer Institute, La Ligue contre le Cancer, the 'Région des Pays de la Loire' and the UNC Lineberger Comprehensive Cancer Center.

Correlation between subsets of tumor-infiltrating immune cells and risk stratification in patients with cervical cancer

Aim

To investigate the correlation between clinicopathological features and risk stratification in cervical cancer patients, and evaluate the feasibility of tumor-infiltrating immune cells as prognostic biomarkers in clinical practice.

Methods

CD3+ tumor infiltrating T cells (TILs), CD45RO+ TILs, CD4+ TILs, CD8+ TILs, FOXP3+ TILs (regulatory T cells, Tregs), CD68+ tumor associated macrophages (TAMs), CD163+ TAMs, and PD-L1+ tumor cells were immunostained in formalin-fixed paraffin-embedded (PPFE) tissues from 96 cervical cancer patients. Immunostaining density and other clinicopathological features such as age, FIGO stage, histopathologic type, Ki67 index, HPV status, lymhovasular invasion status (LVI), lymph node metastasis, tumor size, stromal invasion status, surgical margin status, and parametrial invasion, were evaluated for their roles in risk stratification of cervical cancer patients.

Results

The results showed that significant differences of lymph node metastasis (p = 0.003), surgical margin status (p = 0.020), and stromal invasion status (p = 0.004) existed between lVI(−) and LVI(+) patients. CD3+ TILs in the central tumor area (p = 0.010), CD4+ TILs in the central tumor area (p = 0.045), CD8 + TILs in the central tumor area (p = 0.033), and CD8+ TILs in the invasive margin area (p = 0.004) showed significant differences between lVI(−) and LVI(+) patients. When patients were grouped by status of lymph node metastasis, significant differences of FIGO stage (p = 0.005), LVI status (p = 0.003), CD3+ TILs in the central tumor area (p = 0.045), CD45RO+ TILs in the central tumor area (p = 0.033), and CD45RO+ TILs in the invasive margin area (p = 0.028) were also observed. After the patients were stratified into low-, intermediate-, and high risk groups, significant differences of FIGO stage (p = 0.018), status of lymph node metastasis (p = 0.000), LVI status (p = 0.000), parametrial invasion status (p=0.012), stromal invasion status (p = 0.000), tumor growth pattern (p = 0.015) and tumor size (p = 0.000) were identified among 3 groups of patients, while only CD45RO+ TILs in the invasive margin area (p = 0.018) and FOXP3+ TILs in the central tumor area (p = 0.009) were statistically different among three groups of patients. Spearman’s correlation analysis demonstrated that FIGO stage, LVI status, status of lymph node metastasis, parametrial invasion, stromal invasion status, and tumor size positively correlated with risk stratification (P = 0.005, 0.020, 0.000, 0.022, 0.000, and 0.000 respectively), while CD45RO+ TILs in the invasive margin area and FOXP3+ TILs in the central tumor area showed statistically negative correlation with risk stratification (P = 0.031, 0.009 respectively).

Conclusion

Our study suggested that CD45RO+ TILs in the invasive margin area and FOXP3+ TILs in the central tumor area might be useful biomarkers for risk stratification in cervical cancer patients. Large cohort studies of cervical cancer patients are required to validate our hypothesis.

M1-like macrophage polarization prevails in young children with classic Hodgkin Lymphoma from Argentina

The microenvironment in classical Hodgkin lymphoma (cHL) comprises a mixture of different types of cells, which are responsible for lymphoma pathogenesis and progression. Even though microenvironment composition in adult cHL has been largely studied, only few groups studied pediatric cHL, in which both Epstein Barr virus (EBV) infection and age may display a role in their pathogenesis. Furthermore, our group described that EBV is significantly associated with cHL in Argentina in patients under the age of 10 years old. For that reason, our aim was to describe the microenvironment composition in 46 pediatric cHL patients. M1-like polarization status prevailed in the whole series independently of EBV association. On the other hand, in children older than 10 years, a tolerogenic environment illustrated by higher FOXP3 expression was proved, accompanied by a macrophage polarization status towards M2. In contrast, in children younger than 10 years, M1-like was prevalent, along with an increase in cytotoxic GrB+ cells. This study supports the notion that pediatric cHL exhibits a particular tumor microenvironment composition.

A novel tumor spheroid model identifies selective enhancement of radiation by an inhibitor of oxidative phosphorylation

There is a need for preclinical models that can enable identification of novel radiosensitizing drugs in clinically relevant high-throughput experiments. We used a new high-throughput compatible total cell kill spheroid assay to study the interaction between drugs and radiation in order to identify compounds with radiosensitizing activity. Experimental drugs were compared to known radiosensitizers and cytotoxic drugs clinically used in combination with radiotherapy. VLX600, a novel iron-chelating inhibitor of oxidative phosphorylation, potentiated the effect of radiation in tumor spheroids in a synergistic manner. This effect was specific to spheroids and not observed in monolayer cell cultures. In conclusion, the total cell kill spheroid assay is a feasible high-throughput method in the search for novel radiosensitizers. VLX600 shows encouraging characteristics for development as a novel radiosensitizer.

S100B Protein Stimulates Proliferation and Angiogenic Mediators Release through RAGE/pAkt/mTOR Pathway in Human Colon Adenocarcinoma Caco-2 Cells

Chronic inflammation and angiogenesis are associated with colonic carcinogenesis. Enteric glia-derived S100B protein has been proposed as an "ideal bridge", linking colonic inflammation and cancer, given its dual ability to up-regulate nuclear factor-kappaB (NF-κB) transcription via receptor for advanced glycation end products (RAGE) signaling and to sequestrate wild type pro-apoptotic wild type (wt)p53. However, its pro-angiogenic effects on cancer cells are still uninvestigated. To this aim, we evaluated the effect of exogenous S100B (0.05-5 µM) protein alone or in the presence of S100B blocking monoclonal antibody (mAb) (1:10⁵-1:10⁴ v/v diluted) on (1) cultured Caco-2 cells proliferation, migration and invasiveness in vitro, respectively by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT)-formazan, wound healing and matrigel invasion assays and (2) its effect on the release of pro-angiogenic factors, such as vascular endothelial growth factor (VEGF) by ELISA and immunofluorescence analyses. The effect of S100B alone or in the presence of S100BmAb was then investigated on RAGE/pAkt/mammalian target of rapamycin (mTOR) signaling pathway by immunoblot analysis. Our results showed that S100B markedly increases proliferation and invasiveness of Caco-2 cells, through the release of pro-angiogenic VEGF and NO paralleled to a significant decrease of wtp53 expression mediated by RAGE-p38 mitogen-activated protein kinase (MAPK)/pAkt-mTOR and hypoxia-inducible factor 1-alpha (HIF1α) pathways. Such effects were counteracted by S100BmAb, indicating that S100B targeting is a potential approach to inhibit colon carcinoma proliferation and angiogenesis.

Laminin-derived peptide C16 regulates Tks expression and reactive oxygen species generation in human prostate cancer cells

Laminin peptides influence cancer biology. We investigated the role of a laminin-derived peptide C16 regulating invadopodia molecules in human prostate cancer cells (DU145). C16 augmented invadopodia activity of DU145 cells, and stimulated expression Tks4, Tks5, cortactin, and membrane-type matrix metalloproteinase 1. Reactive oxygen species generation is also related to invadopodia formation. This prompted us to address whether C16 would induce reactive oxygen species generation in DU145 cells. Quantitative fluorescence and flow cytometry showed that the peptide C16 increased reactive oxygen species in DU145 cells. Furthermore, significant colocalization between Tks5 and reactive oxygen species was observed in C16-treated cells. Results suggested that the peptide C16 increased Tks5 and reactive oxygen species in prostate cancer cells. The role of C16 increasing Tks and reactive oxygen species are novel findings on invadopodia activity.

miR-134 inhibits osteosarcoma cell invasion and metastasis through targeting MMP1 and MMP3 in vitro and in vivo

miR-134 has been shown to be associated with angiogenesis and the progression of osteosarcoma. This study further assessed the effects of miR-134 expression on osteosarcoma cell migration, invasion, and metastasis in vitro and in a nude mouse xenograft model, exploring the underlying molecular events. Luciferase reporter assays revealed that miR-134 directly targets the 3'-UTRs of MMP1 and MMP3 to reduce their expression in osteosarcoma cells. In conclusion, overexpression of miR-134 suppresses osteosarcoma cell invasion and metastasis through the inhibition of MMP1 and MMP3 expression. We propose miR-134 as an attractive novel therapeutic target for the treatment of osteosarcoma.

Lymphatic endothelium contributes to colorectal cancer growth via the soluble matrisome component GDF11

Colorectal cancer (CRC) is one of the most malignant tumors worldwide. Stromal cells residing in the tumor microenvironment strongly contribute to cancer progression through their crosstalk with cancer cells and extracellular matrix. Here we provide the first evidence that CRC-associated lymphatic endothelium displays a distinct matrisome-associated transcriptomic signature, which distinguishes them from healthy intestinal lymphatics. We also demonstrate that CRC-associated human intestinal lymphatic endothelial cells regulate tumor cell growth via growth differentiation factor 11, a soluble matrisome component which in CRC patients was found to be associated with tumor progression. Our data provide new insights into lymphatic contribution to CRC growth, aside from their conventional role as conduits of metastasis.

Extracellular Acidosis Modulates the Expression of Epithelial-Mesenchymal Transition (EMT) Markers and Adhesion of Epithelial and Tumor Cells

Epithelial-to-mesenchymal transition (EMT) is an important process of tumor progression associated with increased metastatic potential. EMT can be activated by external triggers such as cytokines or metabolic parameters (e.g. hypoxia). Since extracellular acidosis is a common finding in tumors, the aim of the study is to analyze its impact on the expression of EMT markers in vitro and in vivo as well as the functional impact on cell adhesion. Therefore, three tumor and two normal epithelial cell lines were incubated for 24 h at pH 6.6 and the expression of EMT markers was studied. In addition, mRNA expression of transcription and metabolic factors related to EMT was measured as well as the functional impact on cell adhesion, either during acidic incubation or after priming cells in an acidic milieu. E-cadherin and N-cadherin were down-regulated in all tumor and normal cell lines studied, whereas vimentin expression increased in only two tumor and one normal cell line. Down-regulation of the cadherins was seen in total protein and to a lesser extent in surface protein. In vivo an increase in N-cadherin and vimentin expression was found. Acidosis up-regulated Twist1 and Acsl1 but down-regulated fumarate hydratase (Fh). Cell adhesion during acidic incubation decreased in AT1 prostate carcinoma cells whereas preceding acidic priming increased their subsequent adhesion. Low tumor pH is able to modulate the expression EMT-related proteins and by this may affect the stability of the tissue structure.

TIAM1 promotes chemoresistance and tumor invasiveness in colorectal cancer

Accumulating evidence suggests that cancer cells with stem cell-like features have higher resistance to chemotherapeutic agents. Herein, we identified T-lymphoma invasion and metastasis-inducing protein-1 (TIAM1) as one of the Wnt-signaling associated genes which drives self-renewal and its expression is upregulated by cancer associated fibroblasts (CAFs). TIAM1 expression was assessed in resected colorectal cancer (CRC) tissues from 300 patients who did or did not respond to chemotherapy. siRNA and CRISPR/Cas9 was used to examine whether the inhibition of TIAM1 affects chemosensitivity of CRC. We demonstrate that stemness through Wnt signaling regulates chemosensitivity and this phenomenon occurs exclusively in cancer stem cells. Subsequently, we established patient-derived CAFs and tested whether the drug sensitivity of CRC cell lines is altered with CAF-derived conditioned medium. High-TIAM1 expression correlated significantly with poor prognosis of CRC patients, and was overexpressed in patients who did not respond to chemotherapy. We demonstrated that the inhibition of TIAM1 enhanced sensitivity to chemotherapeutic drugs and reduced tumor invasiveness in a series of experiments in vitro. Moreover, CAF-derived conditioned media increased stemness and chemoresistance in CRC cell lines through TIAM1 overexpression. In addition, we validated TIAM1 associated drug sensitivity using a xenograft model. We have demonstrated that TIAM1 is overexpressed in CRC tumors from patients who did not respond to chemotherapeutic drugs and levels of TIAM1 expression served as an independent prognostic factor. Mechanistically, CAFs enhanced CRC chemoresistance through TIAM1 overexpression. Collectively, these results suggest that TIAM1 regulates chemosensitivity in tumors and stroma and thus may be an attractive therapeutic target.

The lncRNA BORG facilitates the survival and chemoresistance of triple-negative breast cancers

Disseminated breast cancer cells employ adaptive molecular responses following cytotoxic therapeutic insult which promotes their survival and subsequent outgrowth. Here we demonstrate that expression of the pro-metastatic lncRNA BORG (BMP/OP-Responsive Gene) is greatly induced within triple-negative breast cancer (TNBC) cells subjected to environmental and chemotherapeutic stresses commonly faced by TNBC cells throughout the metastatic cascade. This stress-mediated induction of BORG expression fosters the survival of TNBC cells and renders them resistant to the cytotoxic effects of doxorubicin both in vitro and in vivo. The chemoresistant traits of BORG depend upon its robust activation of the NF-κB signaling axis via a novel BORG-mediated feed-forward signaling loop, and via its ability to bind and activate RPA1. Indeed, genetic and pharmacologic inhibition of NF-κB signaling or the DNA-binding activity of RPA1 abrogates the pro-survival features of BORG and renders BORG-expressing TNBCs sensitive to doxorubicin-induced cytotoxicity. These findings suggest that therapeutic targeting of BORG or its downstream molecular effectors may provide a novel means to alleviate TNBC recurrence.

Targeting Tumor Microenvironment for Cancer Therapy

Cancer development is highly associated to the physiological state of the tumor microenvironment (TME). Despite the existing heterogeneity of tumors from the same or from different anatomical locations, common features can be found in the TME maturation of epithelial-derived tumors. Genetic alterations in tumor cells result in hyperplasia, uncontrolled growth, resistance to apoptosis, and metabolic shift towards anaerobic glycolysis (Warburg effect). These events create hypoxia, oxidative stress and acidosis within the TME triggering an adjustment of the extracellular matrix (ECM), a response from neighbor stromal cells (e.g., fibroblasts) and immune cells (lymphocytes and macrophages), inducing angiogenesis and, ultimately, resulting in metastasis. Exosomes secreted by TME cells are central players in all these events. The TME profile is preponderant on prognosis and impacts efficacy of anti-cancer therapies. Hence, a big effort has been made to develop new therapeutic strategies towards a more efficient targeting of TME. These efforts focus on: (i) therapeutic strategies targeting TME components, extending from conventional therapeutics, to combined therapies and nanomedicines; and (ii) the development of models that accurately resemble the TME for bench investigations, including tumor-tissue explants, “tumor on a chip” or multicellular tumor-spheroids.

Cancer-associated fibroblasts induce epithelial-mesenchymal transition of bladder cancer cells through paracrine IL-6 signalling

BACKGROUND

Cancer-associated fibroblasts (CAFs), activated by tumour cells, are the predominant type of stromal cells in cancer tissue and play an important role in interacting with neoplastic cells to promote cancer progression. Epithelial-mesenchymal transition (EMT) is a key feature of metastatic cells. However, the mechanism by which CAFs induce EMT program in bladder cancer cells remains unclear.

METHODS

To investigate the role of CAFs in bladder cancer progression, healthy primary bladder fibroblasts (HFs) were induced into CAFs (iCAFs) by bladder cancer-derived exosomes. Effect of conditioned medium from iCAFs (CM iCAF) on EMT markers expression of non-invasive RT4 bladder cancer cell line was determined by qPCR and Western blot. IL6 expression in iCAFs was evaluated by ELISA and Western blot. RT4 cell proliferation, migration and invasion were assessed in CM iCAF +/- anti-IL6 neutralizing antibody using cyQUANT assay, scratch test and transwell chamber respectively. We investigated IL6 expression relevance for bladder cancer progression by querying gene expression datasets of human bladder cancer specimens from TCGA and GEO genomic data platforms.

RESULTS

Cancer exosome-treated HFs showed CAFs characteristics with high expression levels of αSMA and FAP. We showed that the CM iCAF induces the upregulation of mesenchymal markers, such as N-cadherin and vimentin, while repressing epithelial markers E-cadherin and p-ß-catenin expression in non-invasive RT4 cells. Moreover, EMT transcription factors SNAIL1, TWIST1 and ZEB1 were upregulated in CM iCAF-cultured RT4 cells compared to control. We also showed that the IL-6 cytokine was highly expressed by CAFs, and its receptor IL-6R was found on RT4 bladder cancer cells. The culture of RT4 bladder cancer cells with CM iCAF resulted in markedly promoted cell growth, migration and invasion. Importantly, inhibition of CAFs-secreted IL-6 by neutralizing antibody significantly reversed the IL-6-induced EMT phenotype, suggesting that this cytokine is necessary for CAF-induced EMT in the progression of human bladder cancer. Finally, we observed that IL6 expression is up-regulated in aggressive bladder cancer and correlate with CAF marker ACTA2.

CONCLUSIONS

We conclude that CAFs promote aggressive phenotypes of non-invasive bladder cancer cells through an EMT induced by the secretion of IL-6.

Tumor endothelial cells as a potential target of metronomic chemotherapy

Drug resistance and toxic side effects are major therapeutic hurdles affecting cancer patients receiving conventional chemotherapy based on the maximum tolerated dose. Metronomic chemotherapy (MCT), a new therapeutic approach developed to avoid these problems generally, consists of the continuous administration of low-dose cytotoxic agents without extended intervals. This therapy targets the tumor microenvironment, rather than exerting a direct effect on tumor cells. As a result, the MCT regimen functionally impairs tumor endothelial cells and circulating endothelial progenitor cells, leading to tumor dormancy via anti-angiogenesis. Over the past 10 years, several studies have highlighted the impact of MCT on the tumor microenvironment and angiogenesis and demonstrated its potential as a switch from the pro-angiogenic to the anti-angiogenic state. However, the mechanisms of action are still obscure. Here, we systematically review the evidence regarding the anti-angiogenic potential of MCT as a crucial determinant of tumor dormancy and cancer treatment.

Multipotent mesenchymal stromal cells play critical roles in hepatocellular carcinoma initiation, progression and therapy

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer, with high morbidity, relapse and mortality rates. Multipotent mesenchymal stromal cells (MSCs) can be recruited to and become integral components of the HCC microenvironment and can influence tumor progression. This review discusses MSC migration to liver fibrosis and the HCC microenvironment, MSC involvement in HCC initiation and progression and the widespread application of MSCs in HCC-targeted therapy, thus clarifying the critical roles of MSCs in HCC.

Human endogenous retroviruses role in cancer cell stemness

Cancer incidence and mortality, metastasis, drug resistance and recurrence are still the critical issues of oncological diseases. In this scenario, increasing scientific evidences demonstrate that the activation of human endogenous retroviruses (HERVs) is involved in the aggressiveness of tumors such as melanoma, breast, germ cell, renal, ovarian, liver and haematological cancers. In their dynamic regulation, HERVs have also proved to be important determinants of pluripotency in human embryonic stem cells (ESC) and of the reprogramming process of induced pluripotent stem cells (iPSCs). In many types of tumors, essential characteristics of aggressiveness have been associated with the achievement of stemness features, often accompanied with the identification of defined subpopulations, termed cancer stem cells (CSCs), which possess stem cell-like properties and sustain tumorigenesis. Indeed, CSCs show high self-renewal capacity with a peculiar potential in tumor initiation, progression, metastasis, heterogeneity, recurrence, radiotherapy and drug resistance. However, HERVs role in CSCs biology is still not fully elucidated. In this regard, CD133 is a widely recognized marker of CSCs, and our group demonstrated, for the first time, the requirement of HERV-K activation to expand and maintain a CD133+ melanoma cell subpopulation with stemness features in response to microenvironmental modifications. The review will discuss HERVs expression as cancer hallmark, with particular focus on their role in the regulation of cancer stemness features and the potential involvement as targets for therapy.

Interleukin-23 receptor signaling mediates cancer dormancy and radioresistance in human esophageal squamous carcinoma cells via the Wnt/Notch pathway

Abstract

In the tumor microenvironment, inflammatory cells and molecules influence almost every process; among them, interleukin-23 (IL-23) is a pro-inflammatory molecule that exhibits pro- or anti-tumor properties, but both activities remain poorly understood. In this study, we investigated the effect of extracellular IL-23 in IL-23 receptor-positive (IL-23R⁺) esophageal squamous cell carcinoma (ESCC) and explored the mechanisms underlying this effect. We analyzed ESCC tumor tissues by immunohistochemical and immunofluorescence staining and found that IL-23, which was highly expressed, co-localized with Oct-4A in IL-23R⁺ ESCC cells. In addition, IL-23 treatment significantly increased the accumulation of CD133⁺ cells and activated the Wnt and Notch signaling pathways in CD133⁻IL-23R⁺ ESCC cell lines. Consistently, CD133⁻IL-23R⁺ cells pretreated with IL-23 showed stronger anti-apoptosis activity when exposed to radiation and higher survival than untreated groups. Moreover, the inhibition of Wnt/Notch signaling by a small-molecule inhibitor or siRNA abolished the effect of IL-23-induced dormancy and consequent radioresistance. Taken together, these results suggested that IL-23 facilitates radioresistance in ESCC by activating Wnt/Notch-mediated G0/1 phase arrest, and attenuating these detrimental changes by blocking the formation of dormancy may prove to be an effective pretreatment for radiotherapy.

Key messages

IL-23/IL-23R is correlated with the acquisition of stem-like potential in ESCC.

CD133⁻IL-23R⁺ ESCCs acquired dormancy via IL-23.

Radioresistance depends on IL-23-mediated Wnt/Notch pathway activation in vitro and vivo.

Electronic supplementary material

The online version of this article (10.1007/s00109-018-1724-8) contains supplementary material, which is available to authorized users.

Higher Ki67 expression in fibroblast like cells at invasive front indicates better clinical outcomes in oral squamous cell carcinoma patients

Background: Ki67 has been a key role for the treatment options and prognosis evaluation in some kinds of tumors; however, the spatial expression of Ki67 in oral squamous cell carcinoma (OSCC) has not been fully-evaluated. Therefore, in the present study, we aimed to elucidate the prognosis value of Ki67 spatial expression including in different cell types and at different compartments of tumor in OSCC patients. Methods: Immunohistochemical expression of Ki67 in tumor cells (TCs) and fibroblast like cells (FLCs) at center of tumor (CT) and invasive front (IF) was evaluated in 109 OSCC patients. Then correlations of Ki67 expressions with clinicopathological parameters were analyzed by Chi-square test, and survival curves were evaluated by Kaplan-Meier methods. Furthermore, univariate and multivariate analysis were performed to assess the diagnostic values of Ki67 expression by the Cox regression model. Results: Ki67 expression in TCs was much higher than in FLCs both at CT and IF compartments, but Ki67 expression in TCs was simultaneously higher at CT than that at IF (P=0.0004), which was converse to Ki67 expression in FLCs (P<0.0001). Additionally, high Ki67 expression in FLCs at IF was significantly associated with poor tumor differentiation (P=0.003), worse depth of invasion (DOI, P=0.027) and worst pattern of invasion (WPOI, P=0.041), but Ki67 expression in TCs had no correlation with clinical parameters no matter at CT or IF. Moreover, patients with higher Ki67 expression in TCs at CT had significantly increased risk for OS (overall survival; HR:1.935, 95% CI: 1.181-4.823, P=0.0395) and DFS (disease-free survival; HR: 2.974, 95% CI:1.189-5.023, P=0.046). On contrary, higher Ki67 expression in FLCs at IF was correlated with better OS (HR: 0.15, 95% CI: 0.018-0.846, P=0.0396) and DFS (HR: 0.15, 95% CI: 0.018-0.947, P=0.0445). Whereas, Ki67 expression both at TCs in IF and at FLCs in CT had no significant prognostic value for OS and DFS. Furthermore, Cox multivariate analysis revealed that Ki67 expression in FLCs at IF could not be an independent prognostic factor for OSCC patients. Conclusion: These results show that higher Ki67 expression in FLCs at IF indicated better clinical outcomes for OSCC patients.

ZNF32 induces anoikis resistance through maintaining redox homeostasis and activating Src/FAK signaling in hepatocellular carcinoma

Tumor cells need to attain anoikis resistance to survive prior to metastasis making it a vital trait of malignancy. The molecular mechanism by which hepatocellular carcinoma (HCC) cells resist anoikis remains not fully understood. Here, we report that ZNF32 expression is markedly upregulated in HCC cells upon detachment. Enforced ZNF32 expression significantly promotes the anchorage-independent growth capability of HepG2 and Huh7 cells, whereas knockdown of ZNF32 results in increased apoptosis of HCC cells after detachment. Mechanistically, we demonstrate that ZNF32 overexpression suppresses the reactive oxygen species (ROS) accumulation and maintains mitochondrial membrane potential, leading to ATP, GSH and NADPH elevation and promoting HCC cell survival in response to suspension. Moreover, ZNF32 enhances the phosphorylation and activation of Src/FAK signaling. Src and FAK inhibitors effectively reverse ZNF32-induced anoikis resistance in HCC cells. Collectively, our findings not only reveal a novel and important mechanism by which ZNF32 contributes to anoikis resistance through maintaining redox homeostasis and activating Src/FAK signaling, but also suggest the potential therapeutic value of ZNF32 in HCC patients.

The regulatory roles of lncRNAs in the process of breast cancer invasion and metastasis

Breast cancer (BC) is the most common cancer and principal cause of death among females worldwide. Invasion and metastasis are major causes which influence the survival and prognosis of BC. Therefore, to understand the molecule mechanism underlying invasion and metastasis is paramount for developing strategies to improve survival and prognosis in BC patients. Recent studies have reported that long non-coding RNAs (lncRNAs) play critical roles in the regulation of BC invasion and metastasis through a variety of molecule mechanisms that endow cells with an aggressive phenotype. In this article, we focused on the function of lncRNAs on BC invasion and metastasis through participating in epithelial-to-mesenchymal transition, strengthening cancer stem cells generation, serving as competing endogenous lncRNAs, influencing multiple signaling pathways as well as regulating expressions of invasion-metastasis related factors, including cells adhesion molecules, extracellular matrix, and matrix metallo-proteinases. The published work described has provided a better understanding of the mechanisms underpinning the contribution of lncRNAs to BC invasion and metastasis, which may lay the foundation for the development of new strategies to prevent BC invasion and metastasis.