Tumor hypoxia modulates podoplanin/CCL21 interactions in CCR7+ NK cell recruitment and CCR7+ tumor cell mobilization

Spatiotemporal architecture of immune cells and cancer-associated fibroblasts in high-grade serous ovarian carcinoma

High-grade serous ovarian carcinoma (HGSOC), the deadliest form of ovarian cancer, is typically diagnosed after it has metastasized and often relapses after standard-of-care platinum-based chemotherapy, likely due to advanced tumor stage, heterogeneity, and immune evasion and tumor-promoting signaling from the tumor microenvironment. To understand how spatial heterogeneity contributes to HGSOC progression and early relapse, we profiled an HGSOC tissue microarray of patient-matched longitudinal samples from 42 patients. We found spatial patterns associated with early relapse, including changes in T cell localization, malformed tertiary lymphoid structure (TLS)-like aggregates, and increased podoplanin-positive cancer-associated fibroblasts (CAFs). Using spatial features to compartmentalize the tissue, we found that plasma cells distribute in two different compartments associated with TLS-like aggregates and CAFs, and these distinct microenvironments may account for the conflicting reports about the role of plasma cells in HGSOC prognosis.

Hypoxia as a potential inducer of immune tolerance, tumor plasticity and a driver of tumor mutational burden: Impact on cancer immunotherapy

In cancer patients, immune cells are often functionally compromised due to the immunosuppressive features of the tumor microenvironment (TME) which contribute to the failures in cancer therapies. Clinical and experimental evidence indicates that developing tumors adapt to the immunological environment and create a local microenvironment that impairs immune function by inducing immune tolerance and invasion. In this context, microenvironmental hypoxia, which is an established hallmark of solid tumors, significantly contributes to tumor aggressiveness and therapy resistance through the induction of tumor plasticity/heterogeneity and, more importantly, through the differentiation and expansion of immune-suppressive stromal cells. We and others have provided evidence indicating that hypoxia also drives genomic instability in cancer cells and interferes with DNA damage response and repair suggesting that hypoxia could be a potential driver of tumor mutational burden. Here, we reviewed the current knowledge on how hypoxic stress in the TME impacts tumor angiogenesis, heterogeneity, plasticity, and immune resistance, with a special interest in tumor immunogenicity and hypoxia targeting. An integrated understanding of the complexity of the effect of hypoxia on the immune and microenvironmental components could lead to the identification of better adapted and more effective combinational strategies in cancer immunotherapy. Clearly, the discovery and validation of therapeutic targets derived from the hypoxic tumor microenvironment is of major importance and the identification of critical hypoxia-associated pathways could generate targets that are undeniably attractive for combined cancer immunotherapy approaches.

Advancement in precision diagnosis and therapeutic for triple-negative breast cancer: Harnessing diagnostic potential of CRISPR-cas & engineered CAR T-cells mediated therapeutics

Cancer is characterized by uncontrolled cell growth, disrupted regulatory pathways, and the accumulation of genetic mutations. These mutations across different types of cancer lead to disruptions in signaling pathways and alterations in protein expression related to cellular growth and proliferation. This review highlights the AKT signaling cascade and the retinoblastoma protein (pRb) regulating cascade as promising for novel nanotheranostic interventions. Through synergizing state-of-the-art gene editing tools like the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas system with nanomaterials and targeting AKT, there is potential to enhance cancer diagnostics significantly. Furthermore, the integration of modified CAR-T cells into multifunctional nanodelivery systems offers a promising approach for targeted cancer inhibition, including the eradication of cancer stem cells (CSCs). Within the context of highly aggressive and metastatic Triple-negative Breast Cancer (TNBC), this review specifically focuses on devising innovative nanotheranostics. For both pre-clinical and post-clinical TNBC detection, the utilization of the CRISPR-Cas system, guided by RNA (gRNA) and coupled with a fluorescent reporter specifically designed to detect TNBC's mutated sequence, could be promising. Additionally, a cutting-edge approach involving the engineering of TNBC-specific iCAR and syn-Notch CAR T-cells, combined with the co-delivery of a hybrid polymeric nano-liposome encapsulating a conditionally replicative adenoviral vector (CRAdV) against CSCs, could present an intriguing intervention strategy. This review thus paves the way for exciting advancements in the field of nanotheranostics for the treatment of TNBC and beyond.

Activated fibroblasts in cancer: Perspectives and challenges

Activated fibroblasts in tumors, or cancer-associated fibroblasts (CAFs), have become a popular research area over the past decade. As important players in many aspects of tumor biology, with functions ranging from collagen deposition to immunosuppression, CAFs have been the target of clinical and pre-clinical studies that have revealed their potential pro- and anti-tumorigenic dichotomy. In this review, we describe the important role of CAFs in the tumor microenvironment and the technological advances that made these discoveries possible, and we detail the models that are currently available for CAF investigation. Additionally, we present evidence to support the value of encompassing CAF investigation as a future therapeutic avenue alongside immune and cancer cells while highlighting the challenges that must be addressed for successful clinical translation of new findings.

From gatekeepers to providers: regulation of immune functions by cancer-associated fibroblasts

Cancer-associated fibroblasts (CAFs) are major protumorigenic components of the tumor microenvironment in solid cancers. CAFs are heterogeneous, consisting of multiple subsets that display diverse functions. Recently, CAFs have emerged as major promoters of immune evasion. CAFs favor T cell exclusion and exhaustion, promote recruitment of myeloid-derived suppressor cells, and induce protumoral phenotypic shifts in macrophages and neutrophils. With the growing appreciation of CAF heterogeneity came the understanding that different CAF subpopulations may be driving distinct immune-regulatory effects, interacting with different cell types, and perhaps even driving opposing effects on malignancy. In this review we discuss the current understanding of CAF-immune interactions, their effect on tumor progression and therapeutic response, and the possibility of exploiting CAF-immune interactions as potential targets for cancer therapy.

Expression of Selected miRNAs in Normal and Cancer-Associated Fibroblasts and in BxPc3 and MIA PaCa-2 Cell Lines of Pancreatic Ductal Adenocarcinoma

Therapy for pancreatic ductal adenocarcinoma remains challenging, and the chances of a complete cure are very limited. As in other types of cancer, the expression and role of miRNAs in controlling the biological properties of this type of tumor have been extensively studied. A better insight into miRNA biology seems critical to refining diagnostics and improving their therapeutic potential. In this study, we focused on the expression of miR-21, -96, -196a, -210, and -217 in normal fibroblasts, cancer-associated fibroblasts prepared from a ductal adenocarcinoma of the pancreas, and pancreatic carcinoma cell lines. We compared these data with miRNAs in homogenates of paraffin-embedded sections from normal pancreatic tissues. In cancer-associated fibroblasts and cancer cell lines, miRNAs differed significantly from the normal tissue. In detail, miR-21 and -210 were significantly upregulated, while miR-217 was downregulated. Similar transcription profiles were earlier reported in cancer-associated fibroblasts exposed to hypoxia. However, the cells in our study were cultured under normoxic conditions. We also noted a relation to IL-6 production. In conclusion, cultured cancer-associated fibroblasts and carcinoma cells reflect miR-21 and -210 expression similarly to the cancer tissue samples harvested from the patients.

Podoplanin: Its roles and functions in neurological diseases and brain cancers

Podoplanin is a small mucin-like glycoprotein involved in several physiological and pathological processes in the brain including development, angiogenesis, tumors, ischemic stroke and other neurological disorders. Podoplanin expression is upregulated in different cell types including choroid plexus epithelial cells, glial cells, as well as periphery infiltrated immune cells during brain development and neurological disorders. As a transmembrane protein, podoplanin interacts with other molecules in the same or neighboring cells. In the past, a lot of studies reported a pleiotropic role of podoplanin in the modulation of thrombosis, inflammation, lymphangiogenesis, angiogenesis, immune surveillance, epithelial mesenchymal transition, as well as extracellular matrix remodeling in periphery, which have been well summarized and discussed. Recently, mounting evidence demonstrates the distribution and function of this molecule in brain development and neurological disorders. In this review, we summarize the research progresses in understanding the roles and mechanisms of podoplanin in the development and disorders of the nervous system. The challenges of podoplanin-targeted approaches for disease prognosis and preventions are also discussed.

The Liver X Receptor Is Selectively Modulated to Differentially Alter Female Mammary Metastasis-associated Myeloid Cells

Dysregulation of cholesterol homeostasis is associated with many diseases such as cardiovascular disease and cancer. Liver X receptors (LXRs) are major upstream regulators of cholesterol homeostasis and are activated by endogenous cholesterol metabolites such as 27-hydroxycholesterol (27HC). LXRs and various LXR ligands such as 27HC have been described to influence several extra-hepatic biological systems. However, disparate reports of LXR function have emerged, especially with respect to immunology and cancer biology. This would suggest that, similar to steroid nuclear receptors, the LXRs can be selectively modulated by different ligands. Here, we use RNA-sequencing of macrophages and single-cell RNA-sequencing of immune cells from metastasis-bearing murine lungs to provide evidence that LXR satisfies the 2 principles of selective nuclear receptor modulation: (1) different LXR ligands result in overlapping but distinct gene expression profiles within the same cell type, and (2) the same LXR ligands differentially regulate gene expression in a highly context-specific manner, depending on the cell or tissue type. The concept that the LXRs can be selectively modulated provides the foundation for developing precision pharmacology LXR ligands that are tailored to promote those activities that are desirable (proimmune), but at the same time minimizing harmful side effects (such as elevated triglyceride levels).

A Proteomics Approach to Decipher a Sticky CHO Situation

Chinese hamster ovary (CHO) cells serve as protein therapeutics workhorses, so it is useful to understand what intrinsic properties make certain host cell lines and clones preferable for scale up and production of target proteins. In this study, two CHO host cell lines (H1, H2), and their respective clones were evaluated using comparative TMT‐proteomics. The clones obtained from host H1 showed increased productivity (6.8 times higher) in comparison to clones from host H2. Based on fold‐change analyses, we observed differential regulation in pathways including cell adhesion, aggregation, and cellular metabolism among others. In particular, the cellular adhesion pathway was downregulated in H1, in which podoplanin, an antiadhesion molecule, was upregulated the most in host H1 and associated clones. Phenotypically, these cells were less likely to aggregate and adhere to surfaces. In addition, enzymes involved in cellular metabolism such as isocitrate dehydrogenase (IDH) and mitochondrial‐d‐lactate dehydrogenase ( d‐LDHm) were also found to be differentially regulated. IDH plays a key role in TCA cycle and isocitrate‐alpha‐ketoglutarate cycle while d‐LDHm aids in the elimination of toxic metabolite methylglyoxal, involved in protein degradation. These findings will enhance our efforts towards understanding why certain CHO cell lines exhibit enhanced performance and perhaps provide future cell engineering targets.

Control of Dendritic Cell Function Within the Tumour Microenvironment

The tumour microenvironment (TME) presents a major block to anti-tumour immune responses and to effective cancer immunotherapy. The inflammatory mediators such as cytokines, chemokines, growth factors and prostaglandins generated in the TME alter the phenotype and function of dendritic cells (DCs) that are critical for a successful adaptive immune response against the growing tumour. In this mini review we discuss how tumour cells and the surrounding stroma modulate DC maturation and trafficking to impact T cell function. Fibroblastic stroma and the associated extracellular matrix around tumours can also provide physical restrictions to infiltrating DCs and other leukocytes. We discuss interactions between the inflammatory TME and infiltrating immune cell function, exploring how the inflammatory TME affects generation of T cell-driven anti-tumour immunity. We discuss the open question of the relative importance of antigen-presentation site; locally within the TME versus tumour-draining lymph nodes. Addressing these questions will potentially increase immune surveillance and enhance anti-tumour immunity.

The Role of Podoplanin in Skin Diseases

Podoplanin is a sialomucin-like type I transmembrane receptor glycoprotein that is expressed specifically in lymphatic vessels, sebaceous glands, and hair follicles in normal skin. However, under pathological conditions podoplanin expression is upregulated in various cells, such as keratinocytes, fibroblasts, tumor cells, and inflammatory cells, and plays pivotal roles in different diseases. In psoriasis, podoplanin expression is induced in basal keratinocytes via the JAK-STAT pathway and contributes toward epidermal hyperproliferation. Podoplanin expression on keratinocytes can also promote IL-17 secretion from lymphocytes, promoting chronic inflammation. During wound healing, the podoplanin/CLEC-2 interaction between keratinocytes and platelets regulates re-epithelialization at the wound edge. In skin cancers, podoplanin expresses on tumor cells and promotes their migration and epithelial-mesenchymal transition, thereby accelerating invasion and metastasis. Podoplanin is also expressed in normal peritumoral cells, such as cancer-associated fibroblasts in melanoma and keratinocytes in extramammary Paget's disease, which promote tumor progression and predict aggressive behavior and poor prognosis. This review provides an overview of our current understanding of the mechanisms via which podoplanin mediates these pathological skin conditions.

Modulation of the antitumor immune response by cancer-associated fibroblasts: mechanisms and targeting strategies to hamper their immunosuppressive functions

Cancer-associated fibroblasts (CAFs) are highly heterogeneous players that shape the tumor microenvironment and influence tumor progression, metastasis formation, and response to conventional therapies. During the past years, some CAFs subsets have also been involved in the modulation of immune cell functions, affecting the efficacy of both innate and adaptive anti-tumor immune responses. Consequently, the implication of these stromal cells in the response to immunotherapeutic strategies raised major concerns. In this review, current knowledge of CAFs origins and heterogeneity in the tumor stroma, as well as their effects on several immune cell populations that explain their immunosuppressive capabilities are summarized. The current development of therapeutic strategies for targeting this population and their implication in the field of cancer immunotherapy is also highlighted.

Chemokine signaling in cancer-stroma communications

Cancer is a multi-faceted disease in which spontaneous mutation(s) in a cell leads to the growth and development of a malignant new organ that if left undisturbed will grow in size and lead to eventual death of the organism. During this process, multiple cell types are continuously releasing signaling molecules into the microenvironment, which results in a tangled web of communication that both attracts new cell types into and reshapes the tumor microenvironment as a whole. One prominent class of molecules, chemokines, bind to specific receptors and trigger directional, chemotactic movement in the receiving cell. Chemokines and their receptors have been demonstrated to be expressed by almost all cell types in the tumor microenvironment, including epithelial, immune, mesenchymal, endothelial, and other stromal cells. This results in chemokines playing multifaceted roles in facilitating context-dependent intercellular communications. Recent research has started to shed light on these ligands and receptors in a cancer-specific context, including cell-type specificity and drug targetability. In this review, we summarize the latest research with regards to chemokines in facilitating communication between different cell types in the tumor microenvironment.

Hypoxia increases melanoma-associated fibroblasts immunosuppressive potential and inhibitory effect on T cell-mediated cytotoxicity

Cancer-associated fibroblasts (CAFs) and hypoxia are central players in the complex process of tumor cell-stroma interaction and are involved in the alteration of the anti-tumor immune response by impacting both cancer and immune cell populations. However, even if their independent immunomodulatory properties are now well documented, whether the interaction between these two components of the tumor microenvironment can affect CAFs ability to alter the anti-tumor immune response is still poorly defined. In this study, we provide evidence that hypoxia increases melanoma-associated fibroblasts expression and/or secretion of several immunosuppressive factors (including TGF-β, IL6, IL10, VEGF and PD-L1). Moreover, we demonstrate that hypoxic CAF secretome exerts a more profound effect on T cell-mediated cytotoxicity than its normoxic counterpart. Together, our data suggest that the crosstalk between hypoxia and CAFs is probably an important determinant in the complex immunosuppressive tumor microenvironment.

Ferret Podoplanin Is Detected by PMab-241 in Immunohistochemistry

Podoplanin (PDPN) plays an important role in the development of many normal tissues and is expressed in various cancers. We have previously developed multiple monoclonal antibodies (mAbs) against PDPNs from a variety of animal species and characterized each of these PDPNs using the anti-PDPN mAbs. In this study, we evaluated whether these anti-PDPN mAbs possess cross-reactivity with ferret PDPN (ferPDPN) using flow cytometry. Comprehensive analysis using 17 differing anti-PDPN mAbs available for immunohistochemistry use, demonstrated that the anti-bear PDPN mAb (clone PMab-241) strongly cross-reacts with ferPDPN-overexpressed Chinese hamster ovary-K1 (CHO/ferPDPN) cells. Immunohistochemistry analysis demonstrated intense PMab-241 staining within Bowman's capsules and glomeruli of the ferret kidney, and lymphatic endothelial cells of the ferret lung. These results demonstrate that PMab-241 is suitable for the detection of PDPN in ferret tissues.

Febuxostat Prevents the Cytotoxicity of Propofol in Brain Endothelial Cells

Background and purpose: A high risk of brain injury has been reported with the usage of general anesthetics such as propofol in infants. Experimental data indicated that oxidative stress and inflammation are involved in the neurotoxicity induced by propofol. Febuxostat is a novel anti-gout agent recently reported to exert an anti-inflammatory effect. The present study aims to investigate the protective property of febuxostat against the cytotoxicity of propofol in brain endothelial cells as well as the underlying preliminary mechanism. Methods: The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was utilized to screen the optimized incubation concentration of febuxostat. bEnd.3 brain endothelial cells were stimulated with 2% propofol in the presence or absence of febuxostat (10, 20 μM) for 24 h. The lactate dehydrogenase (LDH) release assay was conducted to detect cytotoxicity. The reactive oxygen species (ROS) levels were evaluated using dichloro-dihydro-fluorescein diacetate (DCFH-DA) staining, and the concentration of reduced glutathione (GSH) was determined using a commercial kit. The expressions of TNF-α, IL-6, IL-12, CXCL-1, PDPN, CXCL8, VCAM-1, and E-selectin were determined using a quantitative real-time polymerase chain reaction (qRT-PCR) and an enzyme-linked immunosorbent assay (ELISA). Western blot and qRT-PCR were utilized to determine the expressions of COX-2 and KLF6. The production of PGE2 was evaluated by ELISA. Results: First, increased LDH release induced by propofol was significantly suppressed by febuxostat. The oxidative stress (elevated ROS levels and decreased GSH level) induced by propofol was alleviated by febuxostat. Second, the upregulated inflammatory factors (TNF-α, IL-6, and IL-12), pro-inflammatory chemokines (CXCL-1, PDPN, and CXCL8), adhesion molecules (VCAM-1 and E-selectin), and inflammatory mediators (COX-2 and PGE2) induced by propofol were greatly downregulated by febuxostat. Lastly, the expression of KLF6 was significantly suppressed by propofol but greatly elevated by febuxostat. Conclusion: Febuxostat prevented the cytotoxicity of propofol in brain endothelial cells by alleviating oxidative stress and inflammatory response through KLF6.

Overexpressed CXCR4 and CCR7 on the surface of NK92 cell have improved migration and anti-tumor activity in human colon tumor model

Successive infusion of natural killer cells is increasingly being explored as a treatment for cancer patients. The inadequate homing of natural killer cells into the tumor site resulted in the poor efficacy of natural killer cells on solid tumors. For the adoptive transfer of tumor-directed natural killer cell has been proved effective, it is hypothesized that there must be more association between the tumor-produced chemokines and the natural killer cells-expressed chemokine receptors. Increased CXCL12 and CCL21 could ameliorated colorectal cancer via generating an anti-tumor environment by preferentially attracting natural killer cells which expressed the chemokine receptor CXCR4 and CCR7. This study demonstrated that overexpressed CXCR4 and CCR7 on the surface of NK92 cell enhanced their migration to human colon cells. Moreover, the administration of such natural killer cells resulted in tumor shrinkage and a significantly increased survival of experimental mice when compared to ones undergoing the treatment of xenografts with natural killer cells expressing only the mock control. These suggested that chemokine receptor engineered natural killer cells could be a promising tool to improve adoptive tumor immunotherapy.

Cancer-associated fibroblasts and their influence on tumor immunity and immunotherapy

Fibroblasts play an essential role in organogenesis and the integrity of tissue architecture and function. Growth in most solid tumors is dependent upon remodeling 'stroma', composed of cancer-associated fibroblasts (CAFs) and extracellular matrix (ECM), which plays a critical role in tumor initiation, progression, metastasis, and therapeutic resistance. Recent studies have clearly established that the potent immunosuppressive activity of stroma is a major mechanism by which stroma can promote tumor progression and confer resistance to immune-based therapies. Herein, we review recent advances in identifying the stroma-dependent mechanisms that regulate cancer-associated inflammation and antitumor immunity, in particular, the interactions between fibroblasts and immune cells. We also review the potential mechanisms by which stroma can confer resistance to immune-based therapies for solid tumors and current advancements in stroma-targeted therapies.

Hypoxia Alters the Expression of CC Chemokines and CC Chemokine Receptors in a Tumor-A Literature Review

Hypoxia, i.e., oxygen deficiency condition, is one of the most important factors promoting the growth of tumors. Since its effect on the chemokine system is crucial in understanding the changes in the recruitment of cells to a tumor niche, in this review we have gathered all the available data about the impact of hypoxia on β chemokines. In the introduction, we present the chronic (continuous, non-interrupted) and cycling (intermittent, transient) hypoxia together with the mechanisms of activation of hypoxia inducible factors (HIF-1 and HIF-2) and NF-κB. Then we describe the effect of hypoxia on the expression of chemokines with the CC motif: CCL1, CCL2, CCL3, CCL4, CCL5, CCL7, CCL8, CCL11, CCL13, CCL15, CCL16, CCL17, CCL18, CCL19, CCL20, CCL21, CCL22, CCL24, CCL25, CCL26, CCL27, CCL28 together with CC chemokine receptors: CCR1, CCR2, CCR3, CCR4, CCR5, CCR6, CCR7, CCR8, CCR9, and CCR10. To better understand the effect of hypoxia on neoplastic processes and changes in the expression of the described proteins, we summarize the available data in a table which shows the effect of individual chemokines on angiogenesis, lymphangiogenesis, and recruitment of eosinophils, myeloid-derived suppressor cells (MDSC), regulatory T cells (T_reg), and tumor-associated macrophages (TAM) to a tumor niche.

Upregulation of mesothelial genes in ovarian carcinoma cells is associated with an unfavorable clinical outcome and the promotion of cancer cell adhesion

A hallmark of ovarian high‐grade serous carcinoma (HGSC) is its early and massive peritoneal dissemination via the peritoneal fluid. It is generally believed that tumor cells must breach the mesothelium of peritoneal organs to adhere to the underlying extracellular matrix (ECM) and initiate metastatic growth. However, the molecular mechanisms underlying these processes are only partially understood. Here, we have analyzed 52 matched samples of spheroids and solid tumor masses (suspected primary lesions and metastases) from 10 patients by targeted sequencing of 21 loci previously proposed as targets of HGSC driver mutations. This analysis revealed very similar patterns of genetic alterations in all samples. One exception was FAT3 with a strong enrichment of mutations in metastases compared with presumed primary lesions in two cases. FAT3 is a putative tumor suppressor gene that codes for an atypical cadherin, pointing a potential role in peritoneal dissemination in a subgroup of HGSC patients. By contrast, transcriptome data revealed clear and consistent differences between tumor cell spheroids from ascites and metastatic lesions, which were mirrored by the in vitro adherence of ascites‐derived spheroids. The adhesion‐induced transcriptional alterations in metastases and adherent cells resembled epithelial–mesenchymal transition, but surprisingly also included the upregulation of a specific subset of mesothelial genes, such as calretinin (CALB2) and podoplanin (PDPN). Consistent with this finding, calretinin staining was also observed in subsets of tumor cells in HGSC metastases, particularly at the invasive tumor edges. Intriguingly, a high expression of either CALB2 or PDPN was strongly associated with a poor clinical outcome. siRNA‐mediated CALB2 silencing triggered the detachment of adherent HGSC cells in vitro and inhibited the adhesion of detached HGSC cells to collagen type I. Our data suggest that the acquisition of a mesenchymal–mesothelial phenotype contributes to cancer cell adhesion to the ECM of peritoneal organs and HGSC progression.

Hypoxia and cancer related pathology

Hypoxic environments occur normally at high altitude, or in underground burrows and in deep sea habitats. They also occur pathologically in human ischemia and in hypoxic solid tumors. Hypoxia in various cancer types and its related molecular mechanisms are associated with a poor clinical outcome. This review will discuss how hypoxia can influence two aspects of tumorigenesis, namely the direct, cell-intrinsic oncogenic effects, as well as the indirect effects on tumor progression mediated by an altered tumor microenvironment. We will also discuss recent progress in identifying the functional roles of hypoxia-related factors (HIFs), along with their regulators and downstream target genes, in cancer stem cells and therapy. Importantly, we propose, using convergent evolution schemes to identify novel biomarkers for both hypoxia adaptation and hypoxic solid tumors as an important strategy in the future.

Podoplanin-Expressing Macrophages Promote Lymphangiogenesis and Lymphoinvasion in Breast Cancer

Among mammary tumor-infiltrating immune cells, the highest expression of podoplanin (PDPN) is found in a subset of tumor-associated macrophages (TAMs). We hereby demonstrate that PDPN is involved in the attachment of this TAM subset to lymphatic endothelial cells (LECs). Mechanistically, the binding of PDPN to LEC-derived galectin 8 (GAL8) in a glycosylation-dependent manner promotes the activation of pro-migratory integrin β1. When proximal to lymphatics, PDPN-expressing macrophages (PoEMs) stimulate local matrix remodeling and promote vessel growth and lymphoinvasion. Anti-integrin β1 blockade, macrophage-specific Pdpn knockout, or GAL8 inhibition impairs TAM adhesion to LECs, restraining lymphangiogenesis and reducing lymphatic cancer spread. In breast cancer patients, association of PoEMs with tumor lymphatic vessels correlates with incidences of lymph node and distant organ metastasis.

Podoplanin in Inflammation and Cancer

Podoplanin is a small cell-surface mucin-like glycoprotein that plays a crucial role in the development of the alveoli, heart, and lymphatic vascular system. Emerging evidence indicates that it is also involved in the control of mammary stem-cell activity and biogenesis of platelets in the bone marrow, and exerts an important function in the immune response. Podoplanin expression is upregulated in different cell types, including fibroblasts, macrophages, T helper cells, and epithelial cells, during inflammation and cancer, where it plays important roles. Podoplanin is implicated in chronic inflammatory diseases, such as psoriasis, multiple sclerosis, and rheumatoid arthritis, promotes inflammation-driven and cancer-associated thrombosis, and stimulates cancer cell invasion and metastasis through a variety of strategies. To accomplish its biological functions, podoplanin must interact with other proteins located in the same cell or in neighbor cells. The binding of podoplanin to its ligands leads to modulation of signaling pathways that regulate proliferation, contractility, migration, epithelial⁻mesenchymal transition, and remodeling of the extracellular matrix. In this review, we describe the diverse roles of podoplanin in inflammation and cancer, depict the protein ligands of podoplanin identified so far, and discuss the mechanistic basis for the involvement of podoplanin in all these processes.

Detection of Alpaca Podoplanin by Immunohistochemistry Using the Antibovine Podoplanin Monoclonal Antibody PMab-44

Podoplanin (PDPN) is expressed in type I alveolar cells of the lungs, lymphatic endothelial cells, and podocytes of the kidneys, and induces platelet aggregation through the C-type lectin-like receptor-2. PDPNs of various animal species have been characterized using specific anti-PDPN monoclonal antibodies (mAbs). However, alpaca PDPN has not previously been characterized because antialpaca PDPN mAbs have not yet been developed. In this study, we investigated the potential cross-reaction between established antibovine PDPN mAbs and alpaca PDPN. Using immunohistochemical analysis, type I alveolar cells of the alpaca lungs were detected by the antibovine PDPN mAb, PMab-44. These results indicate that PMab-44 may be useful for the detection of alpaca PDPN.

Chemokine Receptors and Exercise to Tackle the Inadequacy of T Cell Homing to the Tumor Site

While cancer immune therapy has revolutionized the treatment of metastatic disease across a wide range of cancer diagnoses, a major limiting factor remains with regard to relying on adequate homing of anti-tumor effector cells to the tumor site both prior to and after therapy. Adoptive cell transfer (ACT) of autologous T cells have improved the outlook of patients with metastatic melanoma. Prior to the approval of checkpoint inhibitors, this strategy was the most promising. However, while response rates of up to 50% have been reported, this strategy is still rather crude. Thus, improvements are needed and within reach. A hallmark of the developing tumor is the evasion of immune destruction. Achieved through the recruitment of immune suppressive cell subsets, upregulation of inhibitory receptors and the development of physical and chemical barriers (such as poor vascularization and hypoxia) leaves the microenvironment a hostile destination for anti-tumor T cells. In this paper, we review the emerging strategies of improving the homing of effector T cells (TILs, CARs, TCR engineered T cells, etc.) through genetic engineering with chemokine receptors matching the chemokines of the tumor microenvironment. While this strategy has proven successful in several preclinical models of cancer and the strategy has moved into the first phase I/II clinical trial in humans, most of these studies show a modest (doubling) increase in tumor infiltration of effector cells, which raises the question of whether road blocks must be tackled for efficient homing. We propose a role for physical exercise in modulating the tumor microenvironment and preparing the platform for infiltration of anti-tumor immune cells. In a time of personalized medicine and genetic engineering, this "old tool" may be a way to augment efficacy and the depth of response to immune therapy.

The role of hypoxia in shaping the recruitment of proangiogenic and immunosuppressive cells in the tumor microenvironment

Hypoxia characterizes growing tumors and contributes significantly to their aggressiveness. Hypoxia-inducible factors (HIFs 1 and 2) are stabilized and act differentially as transcription factors on tumor growth and are responsible for important cancer hallmarks such as pathologic angiogenesis, cellular proliferation, apoptosis, differentiation and genetic instability as well as affecting tumor metabolism, tumor immune responses, invasion and metastasis. Taking into account the tumor tissue as a whole and considering the interplay of the various partners which react with hypoxia in the tumor site lead to reconsideration of the treatment strategies. Key limitations of treatment success result from the adaptation to the hypoxic milieu sustained by tumor anarchic angiogenesis. This raises immune tolerance by influencing the recruitment of immunosuppressive cells as bone marrow derived suppressor cells (MDSC) or by impairing the infiltration and killing of tumor cells by cytotoxic cells at the level of the endothelial cell wall of the hypoxic tumor vessels, as summarized in the schematic abstract.

Podoplanin increases the migration of human fibroblasts and affects the endothelial cell network formation: A possible role for cancer-associated fibroblasts in breast cancer progression

In our previous studies we showed that in breast cancer podoplanin-positive cancer-associated fibroblasts correlated positively with tumor size, grade of malignancy, lymph node metastasis, lymphovascular invasion and poor patients’ outcome. Therefore, the present study was undertaken to assess if podoplanin expressed by fibroblasts can affect malignancy-associated properties of breast cancer cells. Human fibroblastic cell lines (MSU1.1 and Hs 578Bst) overexpressing podoplanin and control fibroblasts were co-cultured with breast cancer MDA-MB-231 and MCF7 cells and the impact of podoplanin expressed by fibroblasts on migration and invasiveness of breast cancer cells were studied in vitro. Migratory and invasive properties of breast cancer cells were not affected by the presence of podoplanin on the surface of fibroblasts. However, ectopic expression of podoplanin highly increases the migration of MSU1.1 and Hs 578Bst fibroblasts. The present study also revealed for the first time, that podoplanin expression affects the formation of pseudo tubes by endothelial cells. When human HSkMEC cells were co-cultured with podoplanin-rich fibroblasts the endothelial cell capillary-like network was characterized by significantly lower numbers of nodes and meshes than in co-cultures of endothelial cells with podoplanin-negative fibroblasts. The question remains as to how our experimental data can be correlated with previous clinical data showing an association between the presence of podoplanin-positive cancer-associated fibroblasts and progression of breast cancer. Therefore, we propose that expression of podoplanin by fibroblasts facilitates their movement into the tumor stroma, which creates a favorable microenvironment for tumor progression by increasing the number of cancer-associated fibroblasts, which produce numerous factors affecting proliferation, survival and invasion of cancer cells. In accordance with this, the present study revealed for the first time, that such podoplanin-mediated effects can affect tube formation by endothelial cells and participate in their pathological properties in the tumor context. Our experimental data were supported by clinical studies. First, when IDC and DCIS were analyzed by immunohistochemistry according to the presence of podoplanin-expressing cells, the numbers of cancer-associated fibroblasts with high expression of this glycoprotein were significantly higher in IDC than in DCIS cases. Second, using immunofluorescence, the co-localization of PDPN-positive CAFs with blood vessels stained with antibody directed against CD34 was observed in tumor stroma of IDC samples.