The lung metastatic niche

The origin of brain malignancies at the blood-brain barrier

Despite improvements in extracranial therapy, survival rate for patients suffering from brain metastases remains very poor. This is coupled with the incidence of brain metastases continuing to rise. In this review, we focus on core contributions of the blood-brain barrier to the origin of brain metastases. We first provide an overview of the structure and function of the blood-brain barrier under physiological conditions. Next, we discuss the emerging idea of a pre-metastatic niche, namely that secreted factors and extracellular vesicles from a primary tumor site are able to travel through the circulation and prime the neurovasculature for metastatic invasion. We then consider the neurotropic mechanisms that circulating tumor cells possess or develop that facilitate disruption of the blood-brain barrier and survival in the brain's parenchyma. Finally, we compare and contrast brain metastases at the blood-brain barrier to the primary brain tumor, glioma, examining the process of vessel co-option that favors the survival and outgrowth of brain malignancies.

Implications of the Organ-Specific Immune Environment for Immune Priming Effect of Radiotherapy in Metastatic Setting

With the development of immune checkpoint inhibitors (ICIs), the tumour immune microenvironment (TIME) has been increasingly considered to improve cancer management. The TIME of metastatic lesions is strongly influenced by the underlying immune contexture of the organ in which they are located. The metastatic location itself appears to be an important prognostic factor in predicting outcomes after ICI treatment in cancer patients. Patients with liver metastases are less likely to respond to ICIs than patients with metastases in other organs, likely due to variations in the metastatic TIME. Combining additional treatment modalities is an option to overcome this resistance. Radiotherapy (RT) and ICIs have been investigated together as an option to treat various metastatic cancers. RT can induce a local and systemic immune reaction, which can promote the patient's response to ICIs. Here, we review the differential impact of the TIME according to metastatic location. We also explore how RT-induced TIME modifications could be modulated to improve outcomes of RT-ICI combinations.

Inhibitory effect of aspirin on inflammation-induced lung metastasis of cancer cells associated with neutrophil infiltration

PURPOSE

Systematic inflammation has been reported to contribute to cancer progression through various mechanisms; however, the exact mechanism is still the subject of research. In this study, we evaluated the influence of systematic inflammation on lung metastasis, using a murine abdominal sepsis model, and assessed its relationship with pneumonia after curative esophagectomy in patients with esophageal cancer.

METHODS

We used a murine abdominal sepsis model given highly metastatic osteosarcoma, to reveal the mechanism of systematic inflammation and its potential for lung metastasis. The therapeutic effect of aspirin (ASA) in preventing distant metastasis was also investigated. Subsequently, we analyzed, retrospectively, the relationship between pneumonia and lung metastasis after esophagectomy in patients who underwent esophagectomy at Keio University between January, 2007 and October, 2020.

RESULTS

Abdominal sepsis provoked lung injury in the acute phase. ASA inhibited the recruitment of neutrophils triggered by the lung injury, and it also suppressed lung metastasis. Our retrospective study revealed that lung metastasis was more frequent in patients with postoperative pneumonia.

CONCLUSIONS

Postoperative acute lung injury is associated with a higher risk of lung metastasis. ASA may be a potential preoperative treatment for inhibiting lung metastasis by preventing the recruitment of neutrophils.

Robotic approach may be associated with a lower risk of lung metastases compared to laparoscopic approach for mid-low rectal cancer after neoadjuvant chemoradiotherapy: a multivariate analysis on long-term recurrence patterns

PURPOSE

Describe differences on recurrence patterns of mid-low rectal cancers treated with neoadjuvant chemoradiotherapy and low anterior resection between laparoscopic and robotic approach.

METHODS

Patients were identified from a prospectively maintained institutional database between 2006 and 2019. Demographics, clinicopathological features, recurrence, and survival were investigated. Cox regression analysis was performed for risk factor analysis.

RESULTS

A total of 160 patients (36 laparoscopic and 124 robotic) were included. Systemic recurrence rate was higher in laparoscopic group (27.8 vs 12.1%, p = 0.023). Liver recurrence was similar (11.1 vs 4.0%). Lung recurrence was higher after laparoscopy (19.4 vs 6.5%, p = 0.019). Time to lung recurrence was shorter after laparoscopy (13.0 months, IQR 4.0-20.0) compared to robotic (23.5 months, IQR 17.0-42.7) with no statistical significance. Time to liver recurrence was similar between laparoscopy (19.5 months, IQR 4.7-37.5) and robotic (19.0 months, IQR 10.5-33.0). Median overall survival after lung recurrence was different (p = 0.021) between laparoscopy (19.0 months, IQR 16.0-67.0) and robotic (74.0 months, IQR 50.2-112.2). OS after liver recurrence was similar between groups. Overall survival and lung disease-free survival were different between the two groups (p = 0.032 and p = 0.020), while liver disease-free survival and local recurrence-free survival were not. Laparoscopy (p = 0.030; HR 3.074, 95% CI: 1.112-8.496) was a risk factor for lung disease-free survival on multivariate analysis.

CONCLUSION

Lung recurrences were less frequent and with better overall survival in the robotic group. Liver recurrences were not influenced by choice of approach. Trials are needed to investigate why the robotic approach affects distant metastasis control.

IGF1R acts as a cancer-promoting factor in the tumor microenvironment facilitating lung metastasis implantation and progression

Given the long-term ineffectiveness of current therapies and late-stage diagnoses, lung cancer is a leading cause of malignant diseases. Tumor progression is influenced by cancer cell interactions with the tumor microenvironment (TME). Insulin-like growth factor 1 receptor (IGF1R) was reported to affect the TME; however, the role of IGF1R in lung TME has not been investigated. First, we assessed IGF1R genomic alterations and expression in NSCLC patient tissue samples, as well as IGF1R serum levels. Next, we performed tumor heterotopic transplantation and pulmonary metastases in IGF1R-deficient mice using melanoma and Lewis lung carcinoma (LLC) cells. Herein we report increased amplification and mRNA expression, as well as increased protein expression (IGF1R/p-IGF1R) and IGF1R levels in tumor samples and serum from NSCLC patients, respectively. Moreover, IGF1R deficiency in mice reduced tumor growth, proliferation, inflammation and vascularization, and increased apoptosis after tumor heterotopic transplantation. Following induction of lung metastasis, IGF1R-deficient lungs also demonstrated a reduced tumor burden, and decreased expression of tumor progression markers, p-IGF1R and p-ERK1/2. Additionally, IGF1R-deficient lungs showed increased apoptosis and diminished proliferation, vascularization, EMT and fibrosis, along with attenuated inflammation and immunosuppression. Accordingly, IGF1R deficiency decreased expression of p-IGF1R in blood vessels, fibroblasts, tumor-associated macrophages and FOXP3⁺ tumor-infiltrating lymphocytes. Our results demonstrate that IGF1R promotes metastatic tumor initiation and progression in lung TME. Furthermore, our research indicates that IGF1R could be a potential biomarker for early prediction of drug response and clinical evolution in NSCLC patients.

Periostin in lymph node pre-metastatic niches governs lymphatic endothelial cell functions and metastatic colonization

Although lymph node (LN) metastasis is an important prognostic parameter in cervical cancer, the tissue remodeling at a pre-metastatic state is poorly documented in LNs. We here identified periostin (POSTN) as a component of non-metastatic LNs by applying proteomic analyses and computerized image quantifications on LNs of patients with cervical cancer. We provide evidence for remarkable modifications of POSTN and lymphatic vessel distributions and densities in non-metastatic sentinel and metastatic human LNs, when compared to distant non-metastatic LNs. POSTN deposition at a pre-metastatic stage was demonstrated in a pre-clinical murine model (the ear sponge assay). Its expression by fibroblastic LN cells was assessed by in situ hybridization and in vitro cultures. In vitro, POSTN promoted lymphatic endothelial cell functions and tumor cell proliferation. Accordingly, the in vivo injection of recombinant POSTN together with VEGF-C boosted the lymphangiogenic response, while the metastatic potential of tumor cells was drastically reduced using a POSTN blocking antibody. This translational study also supports the existence of an unprecedented dialog “in cascade”, between the primary tumor and the first pelvic nodal relay in early cervical cancer, and subsequently from pelvic LN to para-aortic LNs in locally advanced cervical cancers. Collectively, this work highlights the association of POSTN deposition with lymphangiogenesis in LNs, and provides evidence for a key contribution of POSTN in promoting VEGF-C driven lymphangiogenesis and the seeding of metastatic cells.

Evaluation of the pharmacological activity of hybrid organotin compounds in a B16 melanoma model in the classical and metronomic administration modes

Introduction: In modern medical chemistry, much attention is paid to the search for new antimetastatic agents based on metal compounds. Organotin compounds promise to be good candidates as the treatment of malignant neoplasms. In order to reduce a possible nonspecific toxic effect of tin compounds and to expand the intended therapeutic use, the paper presents hybrid tin (IV) complexes with Sn-S bond containing a fragment of 2,6-di-tert-butylphenol. The aim of the study was to evaluate the antitumor and antimetastatic effects of bis (3,5-di-tert-butyl-4-hydroxyphenylthiolate) dimethylolol (Me3) and (3,5-di-tert-butyl-4-hydroxyphenylthiolate) triphenylolol (Me5) in a model of transplanted melanoma tumor in B16 mice in classical and metronomic administration mode.

Materials and methods: The efficacy of organotin compounds was studied in a model of a transplanted tumor with spontaneous metastasis of C57Bl/6 (female) melanoma B16 mice using the following indicators: average life expectancy, inhibition of tumor growth by weight, tumor mass, and metastasis inhibition index.

Results and discussion: The most pronounced antimetastatic effect (54% and 36%) is achieved with a five-fold intraperitoneal injection of Me3 and Me5 at the total doses of 375 mg/kg and 250 mg/kg. The comparable results of the efficacy were obtained in the classical and metronomic modes of the injection of hybrid organotin compounds. With an increase in the injected dose, there is an effect of activating the tumor process with the generalized metastasis.

Conclusion: Bis dimethylolol (Me3) and triphenylolol (Me5) compounds demonstrate both a pronounced antimetastatic activity and a multidirectional effect on the growth of the primary focus and the metastasis in lungs, depending on an injected dose.

Metastatic Breast Cancer, Organotropism and Therapeutics: A Review

The final stage of breast cancer involves spreading breast cancer cells to the vital organs like the brain, liver lungs and bones in the process called metastasis. Once the target organ is overtaken by the metastatic breast cancer cells, its usual function is compromised causing organ dysfunction and death. Despite the significant research on breast cancer metastasis, it's still the main culprit of breast cancer-related deaths. Exploring the complex molecular pathways associated with the initiation and progression of breast cancer metastasis could lead to the discovery of more effective ways of treating the devastating phenomenon. The present review article highlights the recent advances to understand the complexity associated with breast cancer metastases, organotropism and therapeutic advances.

CIRCULATING TUMOR CELLS: WHERE WE LEFT OFF?

Cancer metastasis and recurrence are the leading causes of cancer-related death. Tumor cells which leave the primary or secondary tumors and shed into the bloodstream are called circulating tumor cells (CTC). These cells are the key drivers of cancer dissemination to surrounding tissues and to distant organs. The use of CTC in clinical practice necessitates the deep insight into their biology, as well as into their role in cancer evasion of immune surveillance, tumor resistance to chemo- radio- and immunotherapies and metastatic dormancy. Aim. The purpose of the work was to review the current knowledge on the CTC biology, as well as the prospects for their use for the diagnosis and targeted treatment of metastatic disease. Methods. The work proposed the integrative literature review using MEDLINE, Biological Abstracts and EMBASE databases. Results. This review summarizes and discusses historical milestones and current data concerning СTС biology, the main stages of their life cycle, their role in metastatic cascade, clinical prospects for their use as markers for the diagnosis and prognostication of the disease course, as well as targets for cancer treatment. Conclusions. Significant progress in the area of CTC biology and their use in cancer theranostics convincingly proved the attractiveness of these cells as targets for cancer prognosis and therapy. The effective use of liquid biopsy with quantitative and phenotypic characteristics of CTCs is impeded by the imperfection of the methodology for taking biological material and by the lack of reliable markers for assessing the metastatic potential of CTCs of various origins. The variety of mechanisms of tumor cells migration and invasion requires the development of complex therapeutic approaches for anti-metastatic therapy targeting CTCs. Efforts to address these key issues could help developing new and effective cancer treatment strategies.

Tumor-on-chip modeling of organ-specific cancer and metastasis

Every year, cancer claims millions of lives around the globe. Unfortunately, model systems that accurately mimic human oncology - a requirement for the development of more effective therapies for these patients - remain elusive. Tumor development is an organ-specific process that involves modification of existing tissue features, recruitment of other cell types, and eventual metastasis to distant organs. Recently, tissue engineered microfluidic devices have emerged as a powerful in vitro tool to model human physiology and pathology with organ-specificity. These organ-on-chip platforms consist of cells cultured in 3D hydrogels and offer precise control over geometry, biological components, and physiochemical properties. Here, we review progress towards organ-specific microfluidic models of the primary and metastatic tumor microenvironments. Despite the field's infancy, these tumor-on-chip models have enabled discoveries about cancer immunobiology and response to therapy. Future work should focus on the development of autologous or multi-organ systems and inclusion of the immune system.

The pre-metastatic niche in lymph nodes: formation and characteristics

Lymph node metastasis is a crucial prognostic parameter in many different types of cancers and a gateway for further dissemination to distant organs. Prior to metastatic dissemination, the primary tumor prepares for the remodeling of the draining (sentinel) lymph node by secreting soluble factors or releasing extracellular vesicles that are transported by lymphatic vessels. These important changes occur before the appearance of the first metastatic cell and create what is known as a pre-metastatic niche giving rise to the subsequent survival and growth of metastatic cells. In this review, the lymph node structure, matrix composition and the emerging heterogeneity of cells forming it are described. Current knowledge of the major cellular and molecular processes associated with nodal pre-metastatic niche formation, including lymphangiogenesis, extracellular matrix remodeling, and immunosuppressive cell enlisting in lymph nodes are additionally summarized. Finally, future directions that research could possibly take and the clinical impact are discussed.

[Therapeutic Effect of CT-guided ¹²⁵I Seed Implantation on Advanced Lung Cancer and Pulmonary Metastatic Carcinoma]

BACKGROUND

Primary lung cancer and metastatic lung cancer are common malignant tumors of the lung and are the main cause of cancer-related death. Advanced lung cancer and lung metastatic cancer are mainly treated by systemic therapy, and local treatment is also an effective treatment for the refractory or recurrent lesions in the lungs after systemic treatment. ¹²⁵I radioactive particle implantation, as an efficient conformal radiotherapy, has a certain control effect on localized lung cancer. The purpose of this study was to investigate the clinical efficacy and safety of computed tomography (CT) guided percutaneous puncture of lung tissue with ¹²⁵I radioactive particle implantation in the treatment of advanced lung cancer and lung metastatic cancer.

METHODS

Continuouslycollectedthe clinical and pathological data of 105 patients with advanced lung cancer and metastatic lung cancer treated by ¹²⁵I radioactive seed implantation in the Department of Thoracic Surgery, First Affiliated Hospital of Zhejiang University School of Medicine from January 1, 2014 to November 30, 2018. The patients were followed until March, 2019. The clinical efficacy and complications of seedimplantation were analyzed.

RESULTS

A total of 105 patients were included in the study, 78 patients with advanced lung cancer and 27 patients with lung metastases. The median survival time after seed therapy was 395 days. The 1-year survival rate was about 78.1%, and the 2-year survival rate was about 56.1%. Seed implantation for advanced lung cancer is equivalent to lung metastasis. Seed combined with radiofrequency ablation, microwave ablation, and chemotherapy did not improve seed treatment. However, particle combined with external radiation therapy has a significant survival disadvantage compared with simple seed therapy.

CONCLUSIONS

The CT-guided ¹²⁵I radioactive seed implantation has controllable complications and can be used as a safe and effective treatment for advanced lung cancer and lung metastases.

Hypoxia/HIF Modulates Immune Responses

Oxygen availability varies throughout the human body in health and disease. Under physiological conditions, oxygen availability drops from the lungs over the blood stream towards the different tissues into the cells and the mitochondrial cavities leading to physiological low oxygen conditions or physiological hypoxia in all organs including primary lymphoid organs. Moreover, immune cells travel throughout the body searching for damaged cells and foreign antigens facing a variety of oxygen levels. Consequently, physiological hypoxia impacts immune cell function finally controlling innate and adaptive immune response mainly by transcriptional regulation via hypoxia-inducible factors (HIFs). Under pathophysiological conditions such as found in inflammation, injury, infection, ischemia and cancer, severe hypoxia can alter immune cells leading to dysfunctional immune response finally leading to tissue damage, cancer progression and autoimmunity. Here we summarize the effects of physiological and pathophysiological hypoxia on innate and adaptive immune activity, we provide an overview on the control of immune response by cellular hypoxia-induced pathways with focus on the role of HIFs and discuss the opportunity to target hypoxia-sensitive pathways for the treatment of cancer and autoimmunity.

The Proposition of the Pulmonary Route as an Attractive Drug Delivery Approach of Nano-Based Immune Therapies and Cancer Vaccines to Treat Lung Tumors

Lung cancer is the leading cause of cancer related deaths globally, making it a major health concern. The lung’s permissive rich microenvironment is ideal for supporting outgrowth of disseminated tumors from pre-existing extra-pulmonary malignancies usually resulting in high mortality. Tumors occurring in the lungs are difficult to treat, necessitating the need for the development of advanced treatment modalities against primary tumors and secondary lung metastasis. In this review, we explore the pulmonary route as an attractive drug delivery approach to treat lung tumors. We also discuss the potential of pulmonary delivery of cancer vaccine vectors to induce mucosal immunity capable of preventing the seeding of tumors in the lung.

Extracellular Microparticles Encapsulated with Diallyl Trisulfide Interfere with the Inflammatory Tumor Microenvironment and Lung Metastasis of Invasive Melanoma

Lung metastasis is a fatal and late-stage event for many solid tumors. Multiple lines of evidence have demonstrated that diallyl trisulfide (DATS), an active ingredient of garlic, possesses striking antimetastatic effects. However, the lack of highly efficient organ-compatible carriers restricts its application. In the present study, we showed that extracellular microparticles encapsulated with DATS (DATS-MPs) were capable of interfering with the prometastatic inflammatory microenvironment in local tissues. DATS-MPs were successfully prepared and exhibited typical characteristics of B16BL6-derived extracellular vesicles. The DATS-MPs preferentially fused with cancer cells and endogenous cells (mouse lung epithelial MLE-12 cells) from the metastatic organs in vitro. More interestingly, the systemically administered MPs predominantly accumulated in the lung tissue that serves as their main metastatic organ. The drug-loaded MPs exerted higher antimetastatic effects than DATS alone in both the spontaneous and the experimental metastasis models in mice (*p < 0.05). Additionally, we found that DATS-MPs inhibited tumor cell migration and interfered with the prometastatic inflammatory microenvironment via decreasing the release of S100A8/A9, serum amyloid A (SAA), and interleukin-6 (IL-6) and inhibiting the expression of fibronectin, MRP8, myeloperoxidase (MPO), and the toll-like receptor 4 (TLR4)-Myd88 in the lung tissues. Collectively, DATS-MPs appeared to enhance the antimetastatic efficiency of DATS in animal models under study.

Pulmonary gene delivery-Realities and possibilities

Delivery of genetic material to tissues in vivo is an important technique used in research settings and is the foundation upon which clinical gene therapy is built. The lung is a prime target for gene delivery due to a host of genetic, acquired, and infectious diseases that manifest themselves there, resulting in many pathologies. However, the in vivo delivery of genetic material to the lung remains a practical problem clinically and is considered the major obstacle needed to be overcome for gene therapy. Currently there are four main strategies for in vivo gene delivery to the lung: viral vectors, liposomes, nanoparticles, and electroporation. Viral delivery uses several different genetically modified viruses that enter the cell and express desired genes that have been inserted to the viral genome. Liposomes use combinations of charged and neutral lipids that can encapsulate genetic cargo and enter cells through endogenous mechanisms, thereby delivering their cargoes. Nanoparticles are defined by their size (typically less than 100 nm) and are made up of many different classes of building blocks, including biological and synthetic polymers, cell penetrant and other peptides, and dendrimers, that also enter cells through endogenous mechanisms. Electroporation uses mild to moderate electrical pulses to create pores in the cell membrane through which delivered genetic material can enter a cell. An emerging fifth category, exosomes and extracellular vesicles, may have advantages of both viral and non-viral approaches. These extracellular vesicles bud from cellular membranes containing receptors and ligands that may aid cell targeting and which can be loaded with genetic material for efficient transfer. Each of these vectors can be used for different gene delivery applications based on mechanisms of action, side-effects, and other factors, and their use in the lung and possible clinical considerations is the primary focus of this review.

Therapeutic Approaches for Metastases from Colorectal Cancer and Pancreatic Ductal Carcinoma

Metastasis is the process of dissemination of a tumor, whereby cells from the primary site dislodge and find their way to other tissues where secondary tumors establish. Metastasis is the primary cause of death related to cancer. This process warrants changes in original tumoral cells and their microenvironment to establish a metastatic niche. Traditionally, cancer therapy has focused on metastasis prevention by systematic treatments or direct surgical re-sectioning. However, metastasis can still occur. More recently, new therapies direct their attention to targeting cancer stem cells. As they propose, these cells could be the orchestrators of the metastatic niche. In this review, we describe conventional and novel developments in cancer therapeutics for liver and lung metastasis. We further discuss the resistance mechanisms of targeted therapy, the advantages, and disadvantages of diverse treatment approaches, and future novel strategies to enhance cancer prognosis.

Premetastasis

Sterile inflammation within primary tumor tissues can spread to distant organs that are devoid of tumor cells. This happens in a manner dependent on tumor-led secretome, before the actual metastasis occurs. The premetastatic microenvironment is established in this way and is at least partly regulated by hijacking the host innate immune system. The biological manifestation of premetastasis include increased vascular permeability, cell mobilization via the blood stream, degradation of the extracellular matrix, immunosuppression, and host antineoplastic activities.

Critical steps to tumor metastasis: alterations of tumor microenvironment and extracellular matrix in the formation of pre-metastatic and metastatic niche

For decades, cancer metastasis has been a heated topic for its high mortality. Previous research has shown that pre-metastatic niche and metastatic niche are the 2 crucial steps in cancer metastasis, assisting cancerous cells' infiltration, survival, and colonization at target sites. More recent studies have unraveled details about the specific mechanisms related to the modification of pro-invasion environments. Here, we will review literatures on extracellular matrix (ECM) alterations, general cancer metastasis, organ specificity, pre-metastatic niche, metastatic niche, colony formation and impact on the course of metastasis. Respectively, the metastatic mechanisms like effect of hypoxia or inflammation on pre-metastatic niche construction, as well as the interaction between cancer cells and local milieu will be discussed. Based on the evidences of metastatic niches, we revisit and discussed the "Seed and Soil" hypothesis by Paget. This review will seek to provide insight into the mechanism of metastatic organ specificity which pre-metastatic niche and metastatic niche might suggest from an evolutionary aspect.

Switching Homes: How Cancer Moves to Bone

Bone metastases (BM) are a very common complication of the most prevalent human cancers. BM are extremely painful and may be life-threatening when associated with hypercalcaemia. BM can lead to kidney failure and cardiac arrhythmias and arrest, but why and how do cancer cells decide to "switch homes" and move to bone? In this review, we will present what answers science has provided so far, with focus on the molecular mechanisms and cellular aspects of well-established findings, such as the concept of "vicious cycle" and "osteolytic" vs. "osteosclerotic" bone metastases; as well as on novel concepts, such as cellular dormancy and extracellular vesicles. At the molecular level, we will focus on hypoxia-associated factors and angiogenesis, the Wnt pathway, parathyroid hormone-related peptide (PTHrP) and chemokines. At the supramolecular/cellular level, we will discuss tumour dormancy, id est the mechanisms through which a small contingent of tumour cells coming from the primary site may be kept dormant in the endosteal niche for many years. Finally, we will present a potential role for the multimolecular mediators known as extracellular vesicles in determining bone-tropism and establishing a premetastatic niche by influencing the bone microenvironment.

Protective Effect of Traditional Chinese Medicine Formula RP on Lung Microenvironment in Pre-Metastasis Stage of Breast Cancer

Background: Inflammatory response and inflammation-induced vascular hyper-permeability were established leading to the abnormalities of the pulmonary microenvironment in pre-metastasis stage of breast cancer. Ruyiping is a commonly used compound drug for clinical treatment of breast cancer metastasis, and Platycodon grandiflorum is mainly used to treat pulmonary inflammatory diseases. Therefore, this study used ruyiping combined with Platycodon grandiflorum (abbreviated as RP) to investigate their inhibitory effect on pre-metastatic microenvironment of lung in 4T1 tumor-bearing mice. Study Design and Methods: The permeability of lung tissue was detected by Evans blue method. The localization of S100A8/A9 in lung tissue was obtained by double-labeling immunofluorescence staining. The level of fibrinogen in pre-metastatic microenvironment of lung as well as the levels of pro-inflammatory factors (interleukin [IL]-1β and IL-6) and chemokines (CXCL2 and CXCL5) in bronchoalveolar lavage fluid was detected by ELISA (enzyme-linked immunosorbent assay). Results: From the experimental results, RP could protect the integrity of microvascular, inhibit the release of S100A8/A9, reduce the extravasation of fibrinogen, and decrease the expressions of IL-1β, IL-6, CXCL2, and CXCL5. Conclusions: RP could inhibit the extravasation of fibrinogen by protecting pulmonary vascular integrity and then interrupted its interaction with carcinoma in situ, thereby inhibiting the formation of inflammatory pre-metastatic microenvironment.

Stem Cells in Lungs

The respiratory system plays an essential role for human life. This system (like all others) undergoes physiological regeneration due to many types of stem cells found both in the respiratory tract itself and in the alveoli. The stem cell hierarchy is very extensive due to their variety in the lungs and is still not completely understood.The best described lung stem cells are alveolar type II cells, which as progenitor lung stem cells are precursors of alveolar type I cells, i.e., cells that perform gas exchange in the lungs. These progenitor stem cells, which reside in alveoli corners, express high levels of surfactant protein C (SFTPC). Despite the fact that type II pneumocytes occupy only 7-10% of the lung surface, there are almost twice as many as alveolar type I cells occupying almost 95% of the surface.Other stem cells making up the lung regenerative potential have also been identified in the lungs. Both endothelial, mesodermal, and epithelial stem cells are necessary for the lungs to function properly and perform their physiological functions.The lungs, like all other organs, undergo an aging process. As a result of this process, not only the total number of cells changes, the percentage of particular types of cells, but also their efficiency is reduced. With age, the proliferative potential of lung stem cells also decreases, not just their number. This brings about the need to increase the intensity of research in the field of regenerative medicine.

Interleukin-33 activates and recruits natural killer cells to inhibit pulmonary metastatic cancer development

Increasing evidence suggests that IL-33 plays an important role in regulating tumor development. However, conflicting results, obtained from numerous studies, have highlighted the divergent functions of IL-33. The detailed mechanisms by which IL-33 modulates tumor development merit further investigation. Here, we report that IL-33 administration can effectively inhibit the development of pulmonary metastasis of breast cancer in a mouse. In our model, IL-33 promotes the production of TNF-α by macrophages, which increases IL-33 specific receptor (ST2) expression on natural killer (NK) cells and is pivotal in IL-33-induced NK cell activation. IL-33 treatment also facilitates the production of CCL5 in the lung by eosinophils and CD8⁺ T cells, which mediates the recruitment of NK cells to the tumor microenvironment. The systemic activation and local recruitment of NK cells result in potent tumor rejection in the lung. Our study reports a novel mechanism for the IL-33-meditated suppression of metastatic cancer and provides potential therapeutic strategies for targeting metastatic tumor.

Secretomes from metastatic breast cancer cells, enriched for a prognostically unfavorable LCN2 axis, induce anti-inflammatory MSC actions and a tumor-supportive premetastatic lung

Cancer metastasis is responsible for the clear majority of cancer-related deaths. Survival and expansion of cancer cells at secondary sites requires that these premetastatic microenvironments be primed by primary tumor cells and their secreted factors. Efforts to date have been limited by immune-deficient in vivo models and/or the need for finely-tuned analysis time points that reduce contributions from early-disseminating cancer cells. In this regard, we developed a tumor cell-free syngeneic breast cancer model for characterizing tumor cell secretome-mediated reprogramming of premetastatic tissues. We demonstrate that secretomes from metastatic breast cancer cells differentially regulate the lung and brain, promoting a tumor-supportive lung microenvironment with both elevated CD73 expression and decreased TNFα expression. Using in vitro models of CD73-positive mesenchymal stem cells (MSCs) and macrophages/monocytes, we tested whether MSCs can mediate anti-inflammatory effects of metastatic breast cancer cells. Notably, conditioned media from metastatic Py230 cells reprogrammed the secretomes of MSCs toward an anti-inflammatory state. Mining transcriptome data from Py8119 and Py230 cells revealed a lipocalin 2 (LCN2) axis that is selectively expressed in the metastatic Py230 cells, predicts poor breast cancer patient survival and is elevated in circulating serum of mice chronically treated with conditioned media from Py230 cells. Taken together, these results establish the utility of an immune-competent tumor cell-free model for characterizing the mechanisms of breast cancer cell priming of the premetastatic niche, demonstrate that MSCs can mediate the anti-inflammatory effects of metastatic breast cancer cells and substantiate LCN2 as a promising therapeutic target for blocking breast cancer progression.

Proteomic characterization of early lung response to breast cancer metastasis in mice

INTRODUCTION

The tumor-promoting rearrangement of the lungs facilitates the process of cancer cell survival in a foreign microenvironment and enables their protection against immune defense. The study aimed to define the fingerprint of the early rearrangement of the lungs via the proteomic profiling of the lung tissue in the experimental model of tumor metastasis in a murine 4T1 mammary adenocarcinoma.

MATERIALS AND METHODS

The studies were performed on 7-8-week-old BALB/c female mice. Viable 4T1 cancer cells were orthotopically inoculated into the right mammary fat pad. The experiment was performed in the early phase of the tumor metastasis one and two weeks after cancer cell inoculation. The comparative analysis of protein profiles was carried out with the aid of the two-dimensional difference in gel electrophoresis (2D-DIGE). Proteins, of which expression differed significantly, were identified using nano-liquid chromatography coupled to a high-resolution mass spectrometry (nanoLC/hybrid ion trap- Orbitrap XL Discovery).

RESULTS

Palpable primary tumors were noted in the 2^nd week after cancer cell inoculation. The investigated period preceded the formation of numerous macrometastases in the lungs, however the metastasis-promoting changes were visible very early. Primary tumor-induced inflammation developed in the lungs as early as after the 1^st week and progressed during the 2^nd week, accompanied by increased concentration of 2-OH-E⁺, an oxidative stress marker, and imbalance in nitric oxide metabolites, pointing to endothelium dysfunction. The early proteomic changes in the lungs in the 1^st week after 4T1 cell inoculation resulted in the reorganization of lung tissue structure [actin, cytoplasmic 1 (Actb), tubulin beta chain (Tubb5), lamin-B1 (Lmnb1), serine protease inhibitor A3K (Serpina3k)] and activation of defense mechanisms [selenium-binding protein 1 (Selenbp1), endoplasmin (Hsp90b1), stress 70 protein, mitochondrial (Hspa9), heat shock protein HSP 90-beta (Hsp90ab1)], but also modifications in metabolic pathways [glucose-6-phosphate 1-dehydrogenase X (G6pdx), ATP synthase subunit beta, mitochondrial (Atp5b), L-lactate dehydrogenase B chain (Ldhb)]. Further development of the solid tumor after the 2^nd week following cancer cell inoculation, secretion of prolific tumor-derived factors as well as the presence of the increasing number of circulating cancer cells and extravasation processes further impose reorganization of the lung tissue [Actb, vimentin (Vim), clathrin light chain A (Clta)], altering additional metabolic pathways [annexin A5 (Anxa5), Rho GDP-dissociation inhibitor 2 (Arhgdib), complement 1 Q subcomponent-binding protein, mitochondrial (C1qbp), 14-3-3 protein zeta/delta (Ywhaz), peroxiredoxin-6 (Prdx6), chitinase-like protein 4 (Chi3l4), reticulocalbin-1 (Rcn1), EF-hand domain-containing protein D2 (Efhd2), calumenin (Calu)]. Interestingly, many of differentially expressed proteins were involved in calcium homeostasis (Rcn1, Efhd2, Calu, Actb, Vim, Lmnb1, Clta, Tubb5, Serpina3k, Hsp90b1, Hsp90ab1, Hspa9. G6pdx, Atp5b, Anxa5, Arhgdib, Ywhaz).

CONCLUSION

The analysis enabled revealing the importance of calcium signaling during the early phase of metastasis development, early cytoskeleton and extracellular matrix reorganization, activation of defense mechanisms and metabolic adaptations. It seems that the tissue response is an interplay between pro- and anti-metastatic mechanisms accompanied by inflammation, oxidative stress and dysfunction of the barrier endothelial cells.

Cordyceps militaris fraction inhibits the invasion and metastasis of lung cancer cells through the protein kinase B/glycogen synthase kinase 3β/β-catenin signaling pathway

Cordyceps militaris is widely used as a traditional Chinese medicine health supplement, and is also used in the development of anticancer agents. In our previous studies, it was revealed that C. militaris fraction (CMF) possessed an antitumor effect against K562 cells in vitro, induced apoptosis and caused cell cycle arrest in the S phase. The published results also demonstrated that CMF-induced apoptosis was involved in mitochondrial dysfunction. The aim of the present study was to investigate the anti-invasion and anti-metastasis effects of CMF in NCI-H1299 and Lewis lung cancer (LLC) cell lines, which have high metastatic potential. MTT and clone formation assays were initially used to investigate the inhibitory effect of CMF on the viability of NCI-H1299 and LLC cells. The results of cell adhesion, wound healing, migration and Matrigel invasion assays in vitro indicated that NCI-H1299 cells (treated with 1, 3, 10 or 30 µg/ml CMF) and LLC cells (treated with 0.1, 0.3, 1 or 3 µg/ml CMF) demonstrated a concentration-dependent reduction in cell migration and invasion compared with the control. In vivo experiments demonstrated that the oral administration of CMF (65, 130 or 260 mg/kg) decreased the tumor growth and decreased the lung and liver metastasis in an LLC xenograft model, compared with untreated mice. Furthermore, western blot analysis was used to investigate the mechanism of the effect of CMF on the migration of NCI-H1299 cells and metastasis in the xenograft model. The results revealed that CMF may promote glycogen synthase kinase 3β (GSK-3β)-mediated degradation of β-catenin inhibited the phosphorylation of upstream protein kinase B (Akt), which resulted in the attenuation of the expression of matrix metalloproteinase (MMP)-2 and MMP-9. These results suggested that CMF may possess potential for the treatment of lung cancer metastasis via the Akt/GSK-3β/β-catenin pathway.

The role of angiotensin II in cancer metastasis: Potential of renin-angiotensin system blockade as a treatment for cancer metastasis

Hypertension, which often exists as a comorbid condition in cancer patients, is considered as a factor affecting cancer progression. The renin-angiotensin system (RAS) plays an important role in the regulation of blood pressure, and angiotensin II (Ang II) is a well-known pressor peptide in RAS. There is also accumulated evidence indicating that Ang II plays a critical role in the metastasis of various cancers by modulating adhesion, migration invasion, proliferation, and angiogenesis. Consistent with this, large epidemiological studies have reported the potential beneficial effects of angiotensin-converting enzyme (ACE) inhibitors and Ang II type 1 receptor blockers (ARBs) against cancer metastasis; however, some of the results remain controversial. Although the precise Ang II-related mechanisms involved in cancer metastasis are not completely clear yet, a number of basic and meta-analytic studies have shown that ACE inhibitors and ARBs reduce the metastatic potential of tumors. In this review, we summarize the relationships among hypertension, RAS, and metastasis as demonstrated in basic and clinical studies. Finally, we discuss the possibility of using RAS inhibitors as anti-metastatic drugs.

Metastatic Lung Lesions as a Preferred Resection Site for Immunotherapy With Tumor Infiltrating Lymphocytes

Adoptive cell therapy with tumor infiltrating lymphocytes (TIL) yields 50% response rates in metastatic melanoma and shows promising clinical results in other solid tumors. Autologous TIL cultures are isolated from resected tumor tissue, expanded ex vivo to large numbers and reinfused to the preconditioned patient. In this prospective study, we validate the origin of the tumor biopsy and its effect on T-cell function and clinical response. One hundred forty-four patients underwent surgery and 79 patients were treated with TIL adoptive cell therapy. Cultures from lung tissue were compared with other origins. The success rate of establishing TIL culture from lung tissue was significantly higher compared with nonlung tissue (94% vs. 72%, respectively, P≤0.003). Lung-derived TIL cultures gave rise to higher cell numbers (P≤0.011) and exhibited increased in vitro antitumor reactivity. The average fold expansion for lung-derived TIL during a rapid expansion procedure was 1349±557 compared with 1061±473 for nonlung TIL (P≤0.038). Patients treated with TIL cultures of lung origin (compared with nonlung) had prolonged median overall survival (29 vs. 9.5 mo; P≤0.065). Given the remarkable advancement in minimally invasive thoracic surgery and the results of this study, we suggest efforts should be taken to resect lung metastasis rather than other sites to generate TIL cultures for clinical use.

Breast cancer lung metastasis: Molecular biology and therapeutic implications

Distant metastasis accounts for the vast majority of deaths in patients with cancer. Breast cancer exhibits a distinct metastatic pattern commonly involving bone, liver, lung, and brain. Breast cancer can be divided into different subtypes based on gene expression profiles, and different breast cancer subtypes show preference to distinct organ sites of metastasis. Luminal breast tumors tend to metastasize to bone while basal-like breast cancer (BLBC) displays a lung tropism of metastasis. However, the mechanisms underlying this organ-specific pattern of metastasis still remain to be elucidated. In this review, we will summarize the recent advances regarding the molecular signaling pathways as well as the therapeutic strategies for treating breast cancer lung metastasis.

Basic understanding and therapeutic approaches to target toll-like receptors in cancerous microenvironment and metastasis

Toll-like receptors (TLRs) are transmembrane components that sense danger signals, like damage- and pathogen-associated molecular pattern molecules, as receptors, and maintain homeostasis in tissues. They are mainly involved in immune system activation through a variety of mediators, which either carry out (1) elimination of pathogenic threats and redressing homeostatic imbalances or (2) contribution to the initiation and worsening of pathological conditions, including cancers. Under physiological conditions, TLRs coordinate the innate and adaptive immunity, and inhibit autoimmune disorders. In pathological conditions, such as cancer, they can present both tumor and receptor-specific roles. Although the roles of individual TLRs in various cancers have been described, the effects of targeting TLRs to treat cancer and prevent metastasis are still controversial. A growing body of literature has suggested contribution of both activators and inhibitors of TLR signaling pathway for cancer treatment, dependent on several context-specific factors. In short, TLRs can play dual roles with contradictory outcomes in neoplastic conditions. This hampers the development of TLR-based therapeutic interventions. A better understanding of the interwoven TLR pathways in cancerous microenvironment is necessary to design TLR-based therapies. In this review, we consider the molecular mechanisms of TLRs signaling and their involvement in tumor progression. Therapeutic modalities targeting TLRs for cancer treatment are discussed as well.

Regulation of immunity and inflammation by hypoxia in immunological niches

Immunological niches are focal sites of immune activity that can have varying microenvironmental features. Hypoxia is a feature of physiological and pathological immunological niches. The impact of hypoxia on immunity and inflammation can vary depending on the microenvironment and immune processes occurring in a given niche. In physiological immunological niches, such as the bone marrow, lymphoid tissue, placenta and intestinal mucosa, physiological hypoxia controls innate and adaptive immunity by modulating immune cell proliferation, development and effector function, largely via transcriptional changes driven by hypoxia-inducible factor (HIF). By contrast, in pathological immunological niches, such as tumours and chronically inflamed, infected or ischaemic tissues, pathological hypoxia can drive tissue dysfunction and disease development through immune cell dysregulation. Here, we differentiate between the effects of physiological and pathological hypoxia on immune cells and the consequences for immunity and inflammation in different immunological niches. Furthermore, we discuss the possibility of targeting hypoxia-sensitive pathways in immune cells for the treatment of inflammatory disease.

Engineering the pre-metastatic niche

The pre-metastatic niche — the accumulation of aberrant immune cells and extracellular matrix proteins in target organs — primes the initially healthy organ microenvironment and renders it amenable for subsequent metastatic cell colonization. By attracting metastatic cancer cells, mimics of the pre-metastatic niche offer both diagnostic and therapeutic potential. However, deconstructing the complexity of the niche by identifying the interactions between cell populations and the mediatory roles of the immune system, soluble factors, extracellular matrix proteins, and stromal cells has proved challenging. Experimental models need to recapitulate niche-population biology in situ and mediate in vivo tumour-cell homing, colonization and proliferation. In this Review, we outline the biology of the pre-metastatic niche and discuss advances in engineered niche-mimicking biomaterials that regulate the behaviour of tumour cells at an implant site. Such oncomaterials offer strategies for early detection of metastatic events, inhibiting the formation of the pre-metastatic niche, and attenuating metastatic progression.