Different Steps Of Metastasis Research Articles

An Update of Extracellular Vesicle Involvement in Different Steps of Cancer Metastasis and Targeting Strategies.

Cancer metastasis is the deadliest event in tumorigenesis. Despite extensive research, there are still unsolved challenges regarding early metastasis detection and targeting strategies. Extracellular vesicles (EVs) and their impact on tumorigenic-related events are in the eye of current investigations. EVs represent a plethora of biomarkers and information, and they are considered key determinants in tumor progression and for tumor prognosis and monitoring. EVs are one of the key mediators for inter-cellular communications between tumor cells and their nearby stroma. They are involved in different steps of metastasis from invasion toward formation of pre-metastatic niches (PMNs), and final growth and colonization of tumor cells in desired organ/s of the target. Membrane components of EVs and their cargo can be traced for the identification of tumor metastasis, and their targeting is a promising strategy in cancer therapy. In this review, we aimed to discuss the current understanding of EV-based metastatic predilection in cancer, providing updated information about EV involvement in different metastatic steps and suggesting some strategies to hamper this devastating condition.

Understanding the cell survival mechanism of anoikis-resistant cancer cells during different steps of metastasis.

Anchorage-independent survival of cancer cells is associated with metastasis as it enables cells to travel to secondary target sites. Tissue integrity is generally maintained by detachment-induced cell death called 'anoikis', but cancer cells undergoing the multistep metastatic process show resistance to anoikis. Anoikis resistance enables these cells to survive through the extracellular matrix (ECM) deprived phase, which starts when cancer cells detach and move into the circulation till cells reach to the secondary target site. Comprehensive analysis of the molecular and functional biology of anoikis resistance in cancer cells will provide crucial details about cancer metastasis, enabling us to identify novel therapeutic targets against cancer cell dissemination and ultimately secondary tumor formation. This review broadly summarizes recent advances in the understanding of cellular and molecular events leading to anoikis and anoikis resistance. It further elaborates more about the signaling cross-talk in anoikis resistance and its regulation during metastasis.

The genomic architecture of metastasis in breast cancer: focus on mechanistic aspects, signalling pathways and therapeutic strategies.

Breast cancer is a multifactorial, heterogeneous disease and the second most frequent cancer amongst women worldwide. Metastasis is one of the most leading causes of death in these patients. Early-stage or locally advanced breast cancer is limited to the breast or nearby lymph nodes. When breast cancer spreads to farther tissues/organs from its original site, it is referred to as metastatic or stage IV breast cancer. Normal breast development is regulated by specific genes and signalling pathways controlling cell proliferation, cell death, cell differentiation and cell motility. Dysregulation of genes involved in various signalling pathways not only leads to the formation of primary tumour but also to the metastasis as well. The metastatic cascade is represented by a multi-step process including invasion of the local tumour cell followed by its entry into the vasculature, exit of malignant cells from the circulation and ultimately their colonization at the distant sites. These stages are referred to as formation of primary tumour, angiogenesis, invasion, intravasation and extravasation, respectively. The major sites of metastasis of breast cancer are the lymph nodes, bone, brain and lung. Only about 28% five-year survival rate has been reported for stage IV breast cancer. Metastasis is a serious concern for breast cancer and therefore, various therapeutic strategies such as tyrosine kinase inhibitors have been developed to target specific dysregulated genes and various signalling pathways involved in different steps of metastasis. In addition, other therapies like hyperbaric oxygen therapy, RNA interference and CRISPR/Cas9 are also being explored as novel strategies to cure the stage IV/metastatic breast cancer. Therefore, the current review has been compiled with an aim to evaluate the genetic basis of stage IV breast cancer with a focus on the molecular mechanisms. In addition, the therapeutic strategies targeting these dysregulated genes involved in various signalling pathways have also been discussed. Genome editing technologies that can target specific genes in the affected areas by making knock-in and knock-out alternations and thereby bring significant treatment outcomes in breast cancer have also been summarized.

Impact of Immunometabolism on Cancer Metastasis: A Focus on T Cells and Macrophages.

Despite improved treatment options, cancer remains the leading cause of morbidity and mortality worldwide, with 90% of this mortality correlated to the development of metastasis. Since metastasis has such an impact on treatment success, disease outcome, and global health, it is important to understand the different steps and factors playing key roles in this process, how these factors relate to immune cell function and how we can target metabolic processes at different steps of metastasis in order to improve cancer treatment and patient prognosis. Recent insights in immunometabolism direct to promising therapeutic targets for cancer treatment, however, the specific contribution of metabolism on antitumor immunity in different metastatic niches warrant further investigation. Here, we provide an overview of what is so far known in the field of immunometabolism at different steps of the metastatic cascade, and what may represent the next steps forward. Focusing on metabolic checkpoints in order to translate these findings from in vitro and mouse studies to the clinic has the potential to revolutionize cancer immunotherapy and greatly improve patient prognosis.

Tumor pH and metastasis: a malignant process beyond hypoxia.

Tumors often show, compared to normal tissues, a markedly decreased extracellular pH resulting from anaerobic or aerobic glycolysis in combination with a reduced removal of acidic metabolites. Several studies indicate that acidosis induces (independently from hypoxia) hematogenous and lymphatic spread of tumor cells worsening the long-term prognosis of tumor patients. This review gives an overview on the impact of low pH on different steps of metastasis including (a) local tumor cell invasion and angiogenesis, (b) intravasation of tumor cells and detachment into the circulation, and (c) adherence of circulating tumor cells, transmigration and invasion in the new host tissue. The review describes pH-dependent cellular mechanisms fostering these steps such as epithelial-to-mesenchymal transition (EMT), activation of cell migration, degradation of the extracellular matrix, or angiogenesis. The review discusses mechanisms of tumor cells for proton sensing including acid-sensitive ion channels (ASICs, TRPs) or ion transporters (NHE1) and G protein coupled H+-sensors. Finally, the review describes several intracellular signaling cascades activated by H+ sensing mechanisms leading to transcriptional, post-transcriptional, or functional changes in the cell relevant for the metastatic spread. From these studies, different therapeutical approaches are described to overcome tumor acidosis or to interfere with the signaling cascades to reduce the metastatic potential of tumors.

PO-185 Towards dynamic targeting of TGF-β in metastatic melanoma using intravital microscopy

IntroductionMelanoma patients diagnosed with liver metastasis have a poor prognosis. TGF-β inhibitors give mixed results in clinical trials with metastatic melanoma patients. To more specifically target TGF-β in liver metastasis melanoma patients, it is necessary to unravel the spatio-temporal function of the TGF-β pathway in hepatic colonisation of melanoma cells. TGF-β is a multifunctional cytokine that signals via TGF-β receptors and downstream SMAD effector proteins. SMAD proteins regulate transcription by binding, among others, to CAGA elements in the DNA. It can exert both pro-and anti-tumorigenic functions, depending on cellular context. It acts on tumour cells, as well as the tumour micro-environment and the immune system. In metastatic melanoma cells, TGF-β can stimulate invasion and metastasis. To unravel its exact role during the different processes of metastasis, we will investigate the spatio-temporal patterns of TGF-β signalling during metastatic colonisation using intravital microscopy (IVM).Material and methodsSpatio-temporal patterns of TGF-β signalling will be studied in vitro and in vivo. For our in vivo studies, we are using an experimentally induced liver metastasis model, injecting highly aggressive B16F10 melanoma cells in immune competent C57BL/6 mice. By injecting these tumour cells in the mesenteric vein, cells will be transported directly to the liver, the first capillary network the cells will encounter. An abdominal imaging window will be placed after cell injection to visualise the different steps of metastasis in real-time using IVM. We developed a rapid CAGA12-GFP-based transcriptional reporter, which expresses a fluorophore upon TGF-β receptor activation and SMAD binding. Upon the expression of this reporter in B16F10 cells, activation of the TGF-β pathway can be monitored over time. By genetic manipulation of B16F10 cells to express dominant negative or constitutively active TGF-β receptors, the role of TGF-β can be assessed for the different steps of metastasis.Results and discussionsWe confirmed earlier reports showing that B16F10 cells show a transcriptional CAGA response upon TGF-β3 stimulation. Using our liver metastasis model, the injected B16F10 cells are able to perform the steps of metastasis and form liver metastasis within a short time frame. The use of the rapid TGF-β reporter during intravital imaging will show the involvement of the TGF-β pathway in the different phases of metastasis.ConclusionB16F10 cells have a functional TGF-β pathway and are able to colonise the liver.

In Vitro Modeling of Mechanics in Cancer Metastasis.

In addition to a multitude of genetic and biochemical alterations, abnormal morphological, structural, and mechanical changes in cells and their extracellular environment are key features of tumor invasion and metastasis. Furthermore, it is now evident that mechanical cues alongside biochemical signals contribute to critical steps of cancer initiation, progression, and spread. Despite its importance, it is very challenging to study mechanics of different steps of metastasis in the clinic or even in animal models. While considerable progress has been made in developing advanced in vitro models for studying genetic and biological aspects of cancer, less attention has been paid to models that can capture both biological and mechanical factors realistically. This is mainly due to lack of appropriate models and measurement tools. After introducing the central role of mechanics in cancer metastasis, we provide an outlook on the emergence of novel in vitro assays and their combination with advanced measurement technologies to probe and recapitulate mechanics in conditions more relevant to the metastatic disease.

Roles of p38 MAPKs in invasion and metastasis

Cells from primary tumours need to go through several steps to become fully metastatic. During this process, cancer cells acquire the ability to invade, migrate across the surrounding tissue, enter into the circulation and colonize distant organs. In the present paper, we review recent progress in understanding how the p38 MAPK (mitogen-activated protein kinase) signalling pathway participates in the different steps of metastasis. Experimental evidence suggests that tumour cells need to modulate p38 MAPK activity levels to successfully metastasize.

Opposing roles of CXCR4 and CXCR7 in breast cancer metastasis

IntroductionCXCL12-CXCR4 signaling has been shown to play a role in breast cancer progression by enhancing tumor growth, angiogenesis, triggering cancer cell invasion in vitro, and guiding cancer cells to their sites of metastasis. However, CXCR7 also binds to CXCL12 and has been recently found to enhance lung and breast primary tumor growth, as well as metastasis formation. Our goal was to dissect the contributions of CXCR4 and CXCR7 to the different steps of metastasis - in vivo invasion, intravasation and metastasis formation.MethodsWe overexpressed CXCR4, CXCR7 or both in the rat mammary adenocarcinoma cell line MTLn3. Stable expressors were used to form tumors in severe combined immunodeficiency (SCID) mice, and in vivo invasiveness, intravital motility, intravasation, and metastasis were measured.ResultsWe found that CXCR4 overexpression increased the chemotactic and invasive behavior of MTLn3 cells to CXCL12, both in vitro and in vivo, as well as in vivo motility and intravasation. CXCR7 overexpression enhanced primary tumor growth and angiogenesis (as indicated by microvessel density and VEGFA expression), but decreased in vivo invasion, intravasation, and metastasis formation. In vitro, expression of CXCR7 alone had no effect in chemotaxis or invasion to CXCL12. However, in the context of increased CXCR4 expression, CXCR7 enhanced chemotaxis to CXCL12 but decreased invasion in response to CXCL12 in vitro and in vivo and impaired CXCL12 stimulated matrix degradation. The changes in matrix degradation correlated with expression of matrix metalloproteinase 12 (MMP12).ConclusionsWe find that CXCR4 and CXCR7 play different roles in metastasis, with CXCR4 mediating breast cancer invasion and CXCR7 impairing invasion but enhancing primary tumor growth through angiogenesis.

Imaging pH and metastasis

Metastasis is a multistep process that culminates in the spread of cells from a primary tumor to a distant site or organs. For tumor cells to be able to metastasize, they have to locally invade through basement membrane into the lymphatic and the blood vasculatures. Eventually they extravasate from the blood and colonize in the secondary organ. This process involves multiple interactions between the tumor cells and their microenvironments. The microenvironment surrounding tumors has a significant impact on tumor development and progression. A key factor in the microenvironment is an acidic pH. The extracellular pH of solid tumors is more acidic in comparison to normal tissue as a consequence of high glycolysis and poor perfusion. It plays an important role in almost all steps of metastasis. The past decades have seen development of technologies to non-invasively measure intra- and/or extracellular pH. Most successful measurements are MR-based, and sensitivity and accuracy have dramatically improved. Quantitatively imaging the distribution of acidity helps us understand the role of the tumor microenvironment in cancer progression. The present review discusses different MR methods in measuring tumor pH along with emphasizing the importance of extracelluar tumor low pH on different steps of metastasis; more specifically focusing on epithelial-to-mesenchymal transition (EMT), and anti cancer immunity.

Illuminating the metastatic process

Until recently most studies of metastasis only measured the end point of the process--macroscopic metastases. Although these studies have provided much useful information, the details of the metastatic process remain somewhat mysterious owing to difficulties in studying cell behaviour with high spatial and temporal resolution in vivo. The use of luminescent and fluorescent proteins and developments in optical imaging technology have enabled the direct observation of cancer cells spreading from their site of origin and arriving at secondary sites. This Review will describe recent advances in our understanding of the different steps of metastasis gained from cellular resolution imaging, and how these techniques can be used in preclinical drug evaluation.

Inhibition of Platelet Function: Does It Offer a Chance of Better Cancer Progression Control?

Thrombocytosis is frequently (10 to 57%) observed in cancer patients. Although the mechanisms underlying thrombocytosis are not yet fully elucidated, tumor-derived factors with thrombopoietin-like activity, growth factors, platelet-derived microparticles, and factors released from bone marrow endothelial cells as well as growth factors secreted by megakaryocytes (acting via an autocrine loop) are claimed to influence this process. The course of cancer is strongly associated with hypercoagulable state, which results from direct influences of tumor cells themselves and various indirect mechanisms. Activated platelets provide procoagulant surface amplifying the coagulation process. It is well documented that proteins of the hemostatic system influence different steps of metastasis, angiogenesis, and proteolytic events. Much less is known about the role of platelets in tumor growth and their possible contribution to prevention of tumor cells from the host immune system. Multidirectional activities of platelets during tumor development and metastatic dissemination create a possibility of introducing antiplatelet agents in anticancer therapy. The spectrum of plausible therapies includes antibodies against glycoprotein IIb-IIIa, direct thrombin inhibitors, protease activated receptor-1 targeted therapy, as well as cyclooxygenase (COX) and lipoxygenase (LOX) inhibitors. However, there is no sufficient information on a specific type of cancer where progression does depend on platelet function. Despite numerous experimental studies conducted, to date none of the new specific antiplatelet agents were tested in clinical trials in a cancer patient population.

Expression of metastasis-related genes in surgical specimens of human gastric cancer can predict disease recurrence.

It was determined whether the expression level of several genes that regulate different steps of metastasis in formalin-fixed paraffin-embedded archival specimens of human gastric cancers correlated with disease recurrence and metastasis. The steady-state mRNA expression level for epidermal growth factor receptor (EGF-R), basic fibroblast growth factor (bFGF), E-cadherin, type IV collagenase and multidrug resistance (MDR-1) were examined by a colorimetric in situ hybridisation (ISH) technique, concentrating on reactivity at the periphery of the lesions. All patients were operated on for cure. 15 cases were disease-free and 10 had disease recurrence by 4.5 years after resection of the primary tumours. The expression of EGF-R and bFGF type IV collagenase was higher and expression of E-cadherin was lower in the disease-recurrence cases than in the disease-free cases. The ratio between the expression level of collagenase type IV and E-cadherin at the periphery of the surgical specimens differed significantly between the disease-free cases and the recurrent-metastatic cases. These data show that multiparametric ISH analysis for several metastasis-related genes may allow prediction of disease recurrence of gastric cancer.

EPIGENETIC REGULATION OF MULTIDRUG-RESISTANCE AND METASTASIS-RELATED GENES IN HUMAN LUNG ADENOCARCINOMA CELLS GROWING IN ECTOPIC OR ORTHOTOPIC ORGANS OF NUDE-MICE

We examined whether the organ microenvironment modulates the response of the human lung adenocarcinoma cell line DMS-4C to doxorubicin (DXR). DMS-4C cells were injected intrathoracically (orthotopic) and subcutaneously (ectopic) into nude mice. The mice were given intravenous (i.v.) injections of DXR (8 mg/kg) or saline (control) on days 50 and 58 after implantation, Tumors growing in the subcutis were more sensitive to DXR than tumors growing in the lung. Tumor cells established in culture from lung lesions were initially more resistant to DXR than cells established in culture from subcutaneous (s.c.) tumors. After 14 days in culture, all cells exhibited similar sensitivity to DXR. The expression level of several genes that regulate different steps of metastasis, basic fibroblast growth factor (angiogenesis), type IV collagenase (invasion), epidermal growth factor receptor (growth), and mdr1 (drug resistance), was examined by an in situ mRNA hybridization technique in DMS-4C lesions from the lung and subcutis. Higher mRNA expression for Mdr1, bFGF, and type IV collagenase was found in lung lesions than in s.c. tumors. These results demonstrate that the organ environment influences the expression of several metastasis-related genes in human lung adenocarcinoma cells.