Influence Of Tumor Microenvironment Research Articles

Exosomes in tumor microenvironment influence cancer progression and metastasis.

Exosomes are small membrane vesicles of endocytic origin with a size of 50-100 nm. They can contain microRNAs, mRNAs, DNA fragments, and proteins, which are shuttled from a donor cell to recipient cells. Many different cell types including immune cells, mesenchymal cells, and cancer cells release exosomes. There is emerging evidence that cancer-derived exosomes contribute to the recruitment and reprogramming of constituents associated with tumor environment. Here, we discuss different mechanisms associated with biogenesis, payload, and transport of exosomes. We highlight the functional relevance of exosomes in cancer, as related to tumor microenvironment, tumor immunology, angiogenesis, and metastasis. Exosomes may exert an immunosuppressive function as well as trigger an anti-tumor response by presenting tumor antigens to dendritic cells. Exosomes may serve as cancer biomarkers and aid in the treatment of cancer.

New Insights into Pathogenesis, Diagnosis, and Treatment of Pancreatic Disorders

New Insights into Pathogenesis, Diagnosis, and Treatment of Pancreatic Disorders

Microenvironment Elements Involved in the Development of Pancreatic Cancer Tumor

Introduction. In spite of intensive research during many years, pancreatic adenocarcinoma remains one of the deadliest cancers. The surgical intervention remains main possibility of treatment because chemotherapy and radiotherapy has a minimal impact on long-term survival. We are still looking for the weak points of this devastating disease. Materials and Methods. Pancreatic tumor tissue samples were collected from 36 patients. Immunohistochemistry staining was used to evaluate expression of growth factors and immune infiltrates. Activity of MMP2 and MMP9 was assessed by gelatin zymography on 7.5% SDS-PAGE gel with 0.1% gelatin. Results. All growth factors were strongly expressed in pancreatic tumor tissue. We found that level of expression of c-Met receptor was higher for G3 tumors than for G2 tumors. Also we found that active MMP2 was present at all stages of tumor while active MMP9 just at more advanced tumors. Abundant immune cells infiltration was distinctive for tumor tissue, especially macrophages were infiltrating tumor tissue. We found that amount of macrophages was associated with lymph nodes metastases. Conclusion. In our research we demonstrated that among many factors influencing tumor microenvironment c-Met receptor, infiltrating macrophages and MMP2 have significant influence on development and invasion of pancreatic cancer.

Low Levels of Lipogenic Enzymes in Peritumoral Adipose Tissue of Colorectal Cancer Patients

Lipoprotein lipase (LPL) is the crucial enzyme for intravascular catabolism of triglyceride-rich lipoproteins. Fatty acid synthase (FAS) is a key anabolic enzyme that catalyzes the terminal steps in the novo biosynthesis of 18:2n-6. The involvement of both LPL and FAS in tumor biology has been widely demonstrated in different studies and to verify whether there are regional differences in the expression of these enzymes in visceral adipose tissue from patients with colorectal cancer might be representative of events which sustain tumor growth. The objective of this study was to evaluate LPL and FAS activity and expression of their genes in adipose tissue adjacent to neoplasia and distant from it from patients operated for colorectal cancer. LPL enzymatic activity was evaluated by a fluorescent method and FAS activity by a radiometer assay. Reverse-transcription and real-time PCR were used to detect mRNA levels of two enzymes. Our findings show a significant reduction in both LPL and FAS gene expression and activity levels in adipose tissue adjacent to tumor lesion compared to those detected in paired tissue distant from neoplasia. These results underline the influence of tumor microenvironment on lipid metabolism in adipose tissue, demonstrating a tumor-induced impairment in the formation and lipid storing capacity of adipose tissue in patients with colorectal cancer.

Influence of glioma tumour microenvironment on the transport of ANG1005 via low-density lipoprotein receptor-related protein 1

Background:ANG1005 consists of three molecules of paclitaxel conjugated via ester bonds to the 19-amino-acid peptide Angiopep-2. The new chemical agent has been shown to cross the blood–brain barrier (BBB) by receptor-mediated transcytosis via low-density lipoprotein receptor-related protein 1 (LRP1). The experiments here examined the role of LRP1 in the subsequent endocytosis of drug into cancer cells.Methods:Localisation of ANG1005 and Angiopep-2 was examined by immunohistochemistry and in-vivo near-infrared fluorescence imaging in mice carrying orthotopic glioma tumours. Transport of ANG1005 and Angiopep-2 was examined in U87 glioblastoma cell lines.Results:Systemically administered ANG1005 and Cy5.5Angiopep-2 localised to orthotopic glioma tumours in mice. The glioma transplants correlated with high expression levels of LRP1. Decreasing LRP1 activity, by RNA silencing or LRP1 competitors, decreased uptake of ANG1005 and Angiopep-2 into U87 glioblastoma cells. Conversely, LRP1 expression and endocytosis rates for ANG1005 and Angiopep-2 increased in U87 cells under conditions that mimicked the microenvironment near aggressive tumours, that is, hypoxic and acidic conditions.Conclusion:ANG1005 might be a particularly effective chemotherapeutic agent for the wide array of known LRP1-expressing brain and non-brain cancers, in particular those with an aggressive phenotype.

Hepatic Carcinoma—Associated Fibroblasts Promote an Adaptative Response in Colorectal Cancer Cells That Inhibit Proliferation and Apoptosis: Nonresistant Cells Die by Nonapoptotic Cell Death

Carcinoma-associated fibroblasts (CAFs) are important contributors of microenvironment in determining the tumor’s fate. This study aimed to compare the influence of liver microenvironment and primary tumor microenvironment on the behavior of colorectal carcinoma. Conditioned medium (CM) from normal colonic fibroblasts (NCFs), CAFs from primary tumor (CAF-PT) or liver metastasis (CAF-LM) were obtained. We performed functional assays to test the influence of each CM on colorectal cell lines. Microarray and gene set enrichment analysis (GSEA) were performed in DLD1 cells cultured in matched CM. In DLD1 cells, CAF-LM CM compared with CAF-PT CM and NCF led to a more aggressive phenotype, induced the features of an epithelial-to-mesenchymal transition more efficiently, and stimulated migration and invasion to a greater extent. Sustained stimulation with CAF-LM CM evoked a transient G2/M cell cycle arrest accompanied by a reduction of apoptosis, inhibition of proliferation, and decreased viability of SW1116, SW620, SW480, DLD1, HT-29, and Caco-2 cells and provoked nonapoptotic cell death in those cells carrying KRAS mutations. Cells resistant to CAF-LM CM completely changed their morphology in an extracellular signal-regulated protein kinase-dependent process and depicted an increased stemness capacity alongside the Wnt pathway stimulation. The transcriptomic profile of DLD1 cells treated with CAF-LM CM was associated with Wnt and mitogen-activated protein kinase pathways activation in GSEA. Therefore, the liver microenvironment induces more efficiently the aggressiveness of colorectal cancer cells than other matched microenvironments do but secondarily evokes cell death. Resistant cells displayed higher stemness capacity.

Valerie Weaver: Overcoming cancer's stiff resistance

Weaver investigates the mechanical properties of tumors and how changes in the tumor microenvironment influence cancer cell behavior.

Prostate cancer stem cells and their potential roles in metastasis

Most solid tumors have now been reported to contain stem cell-like cells called cancer stem cells (CSCs). These cells are endowed with high tumorigenic capacity and may be the cells that drive tumor formation, maintain tumor homeostasis, and mediate tumor metastasis. Since these self-renewing cancer cells may be the sole population to develop a primary tumor, it is predicted that CSCs may also represent the lethal seeds of metastasis, as supported by a flurry of recent studies on the relationship between CSCs and metastasis. Herein, we summarize current knowledge of stem/progenitor cells and CSCs, especially in the context of normal human prostate and prostate cancer. We further update the recently gained knowledge on the involvement of CSCs in metastasis. We also discuss the fundamental influence of tumor microenvironment on the manifestation of CSCs and metastasis. Finally, we discuss the clinical implication of CSC-based therapy.

Abstract A6: Cancer-associated fibroblasts (CAF) expressing CD44 high increased the aggressiveness of cancer cells

Abstract Cancer-associated fibroblast (CAF) is considered of one of the most important factors influencing tumor microenvironment. CD44 is known to a marker of head and neck cancer stem cell and is a glycoprotein involved in cell-cell interactions, cell adhesion and migration. Tissues from several head and neck cancer patients were gathered and fibroblasts from tumor tissues and normal tissues away from cancer were isolated. We found CAF overexpressed CD44 when compared to normal part of fibroblast, thus investigated the role of CAF which is overexpressing CD44. Cancer cells which are co-cultured with CAF migrated better than normal fibroblast when wound assay were performed. To test whether this motility of cancer is related to CD44 on CAF, CAF was inhibited by neutralizing antibody of CD44. After treatment with neutralizing antibody, the motility of cancer cells reduced. To confirm that CAF influences tumor cell migration, mixture of CAF and cancer cells were laid on an upper well, then these cells would travel 3D environment which is made by our own idea. Cancer cells which get ability to migrate and can form colonies can survive on the bottom well. When treated neutralizing antibody, cells could neither migrate nor make colonies well than antibody-free mixture. In conclusion, CAF influenced cancer cell migration through the CD44. If CD44 on CAF was blocked, the movement and aggressiveness of cancer cells weakened. Citation Information: Clin Cancer Res 2010;16(14 Suppl):A6.

Molecular aspects of prostate cancer: recent data from the literature

A meta-analysis of recent data from the literature underscores the considerable body of present knowledge concerning prostate carcinogenesis, in part due to the numerous molecular biology tools now at our disposal. As concerns early events, much interest is being paid to modifications in the expression of GSTP1 and NKX3.1 occurring in totipotent stem cell populations. The discovery of fusion genes implicating TMPRSS2 and ERG (and, on rare occasions, other ETS family transcription factors) constitutes a major advance. Under physiological androgenic stimulation, the presence of these fusion genes leads to overexpression of genes involved in cell growth and differentiation. Concomitantly, alterations in numerous signalling pathways (growth factors, Wnt-beta catenine, PI3K/Akt) are responsible for the onset of an aggressive tumor phenotype. Hormono-independence is currently explained by an amplification of, or mutations in, androgenic receptors. These are facilitated by genomic instabilities linked to alterations in proteins which regulate gene expression, such as EZH2, and by the influence of the tumor microenvironment. Disturbances in the interactions between tumor cells and the microenvironment contribute to local extension of the tumor. Changes in the expression of E-cadherin are responsible for modifications in cell adhesion to the extracellular matrix. The expression of metalloproteases and of angiogenic factors favors tumor dissemination. Finally, the bone tropism in prostate metastases is probably linked to osteomimetic properties of prostate tumor cells which are capable of expressing certain proteins involved in bone remodelling, such as Runx-2, BSP (bone sialoprotein) and BMP (bone morphogenetic protein). Numerous studies remain to be carried out in order to correlate the identified genetic profiles and molecular anomalies with tumor prognosis. Nevertheless, the possibility of decrypting these anomalies for use in therapeutic applications is encouraging.

Tumor‐derived factors impaired motility and immune functions of dendritic cells through derangement of biophysical characteristics and reorganization of cytoskeleton

The generation and progress of tumors are accompanied with a marked suppression of human immune system. To explore the mechanisms by which tumors escape from immune recognition, we studied the influences of tumor microenvironment on differentiation of dendritic cells (DCs), which play an important role in tumor immunology, by biophysical and immunological methods. It was found that the cytokines derived from tumors caused an increase in osmotic fragility and a decrease in membrane fluidity of DCs, disordering and elevated expression levels of cytoskeleton, and changes of the gene transcriptional levels and energy status of the cells. Moreover, IL-12 production and the expression levels of some surface-marker molecules were also suppressed. These changes led to impaired capabilities of antigen uptake, cell motility and naïve T cell activation; the abnormal biophysical characteristics of DCs may be one aspect of the immune escape mechanism of tumor. These results provide insights into the importance of the reconstruction of tumor microenvironment for immunotherapy based on the anti-cancer activities of DCs.

Does the tumor microenvironment influence radiation-induced apoptosis?

Cytotoxic anti-cancer agents induce apoptosis in tumor and normal tissues. Therefore, it is important to investigate which factors determine these apoptotic processes and hence their likely impact on therapeutic gain. Radiation-induced apoptosis in tumors may be inhibited due to mutations of apoptotic elements or to tumor microenvironmental conditions arising from vascular insufficiency. Tumors typically contain regions of hypoxia, low glucose and acidosis. Hypoxic cells compromise treatment partly because of reduced fixation of damage during radiotherapy and partly because they promote a more malignant phenotype. There is also evidence that hypoxia may inhibit apoptosis. For some cell types, concurrent hypoxia may modulate radiation-induced apoptosis while, for others, post-irradiation hypoxia may be required. This may reflect the activity of different apoptotic pathways. Pathways involving mitochondrial components as well as regulation of SAPK and Fas have been implicated. In addition, several key stages in apoptosis are sensitive to depletion of cellular energy reserves, which results from hypoxia and low glucose conditions. There is also evidence that low pH in tumors can interfere with radiation-induced apoptosis, partly through cell cycle arrest and other undefined mechanisms. Hypoxia, low glucose and acidosis influence radiation-induced apoptosis and thus may be detrimental to radiotherapy.