Platelets promote osteosarcoma cell growth through activation of the platelet-derived growth factor receptor-Akt signaling axis

Extracellular Vesicles, Circulating Tumor Cells, and Immune Checkpoint Inhibitors: Hints and Promises

Immune checkpoint inhibitor (ICI) therapy has revolutionized the treatment of cancer, in particular lung cancer, while the introduction of predictive biomarkers from liquid biopsies has emerged as a promising tool to achieve an effective and personalized therapy response. Important progress has also been made in the molecular characterization of extracellular vesicles (EVs) and circulating tumor cells (CTCs), highlighting their tremendous potential in modulating the tumor microenvironment, acting on immunomodulatory pathways, and setting up the pre-metastatic niche. Surface antigens on EVs and CTCs have proved to be particularly useful in the case of the characterization of potential immune escape mechanisms through the expression of immunosuppressive ligands or the transport of cargos that may mitigate the antitumor immune function. On the other hand, novel approaches, to increase the expression of immunostimulatory molecules or cargo contents that can enhance the immune response, offer premium options in combinatorial clinical strategies for precision immunotherapy. In this review, we discuss recent advances in the identification of immune checkpoints using EVs and CTCs, their potential applications as predictive biomarkers for ICI therapy, and their prospective use as innovative clinical tools, considering that CTCs have already been approved by the Food and Drug Administration (FDA) for clinical use, but providing good reasons to intensify the research on both.

Revisiting 'Hallmarks of Cancer' In Sarcomas

There is no doubt that anyone who has participated in cancer care or research has once read the 'Hallmarks of Cancer' papers published by Hanahan and Weinberg in 2001 and 2011. They initially defined the six qualities of cancer cells as cancer hallmarks in 2001, but expanded that to 11 as a next generation in 2011. In their papers, they discussed the potential treatment strategies against cancer corresponding to each of the 11 hallmarks, and to date, proposed therapies that target genes and signaling pathways associated with each of these hallmarks have guided a trail that cancer treatments should take, some of which are now used as standard in clinical practice and some of which have yet to progress that far. Along with the recent advances in cancer research such as genomic analysis with next generation sequencing, they can be reconverged to an alternative six categories defined as selective proliferative advantages, altered stress response, deregulated cellular metabolism, immune modulation and inflammation, tumor microenvironment, tissue invasion and metastasis. In this paper, we will overview the current state of these alternative hallmarks and their corresponding treatments in the current sarcoma practice, then discuss the future direction of sarcoma treatment.

The dynamic role of platelets in cancer progression and their therapeutic implications

Systemic antiplatelet treatment represents a promising option to improve the therapeutic outcomes and therapeutic efficacy of chemotherapy and immunotherapy due to the critical contribution of platelets to tumour progression. However, until recently, targeting platelets as a cancer therapeutic has been hampered by the elevated risk of haemorrhagic and thrombocytopenic (low platelet count) complications owing to the lack of specificity for tumour-associated platelets. Recent work has advanced our understanding of the molecular mechanisms responsible for the contribution of platelets to tumour progression and metastasis. This has led to the identification of the biological changes in platelets in the presence of tumours, the complex interactions between platelets and tumour cells during tumour progression, and the effects of platelets on antitumour therapeutic response. In this Review, we present a detailed picture of the dynamic roles of platelets in tumour development and progression as well as their use in diagnosis, prognosis and monitoring response to therapy. We also provide our view on how to overcome challenges faced by the development of precise antiplatelet strategies for safe and efficient clinical cancer therapy.

Macrophages and platelets in liver fibrosis and hepatocellular carcinoma

During fibrosis, (myo)fibroblasts deposit large amounts of extracellular matrix proteins, thereby replacing healthy functional tissue. In liver fibrosis, this leads to the loss of hepatocyte function, portal hypertension, variceal bleeding, and increased susceptibility to infection. At an early stage, liver fibrosis is a dynamic and reversible process, however, from the cirrhotic stage, there is significant progression to hepatocellular carcinoma. Both liver-resident macrophages (Kupffer cells) and monocyte-derived macrophages are important drivers of fibrosis progression, but can also induce its regression once triggers of chronic inflammation are eliminated. In liver cancer, they are attracted to the tumor site to become tumor-associated macrophages (TAMs) polarized towards a M2- anti-inflammatory/tumor-promoting phenotype. Besides their role in thrombosis and hemostasis, platelets can also stimulate fibrosis and tumor development by secreting profibrogenic factors and regulating the innate immune response, e.g., by interacting with monocytes and macrophages. Here, we review recent literature on the role of macrophages and platelets and their interplay in liver fibrosis and hepatocellular carcinoma.

Evaluation of cell surface vimentin positive circulating tumor cells as a prognostic biomarker for stage III/IV colorectal cancer

Currently, little is known about the phenotypes of circulating tumor cells (CTCs), particularly epithelial and mesenchymal phenotypes, and their impact on the prognosis of colorectal cancer (CRC) patients. This study aims to investigate the CTC phenotypes and their prognostic implications in stage III/IV CRC. Patients who were diagnosed with CRC and underwent CTC detection at two hospitals were included. CTCs were detected using a mesenchymal CTC kit, and the clinical and pathological characteristics of CTCs were compared with those of cell surface vimentin-positive CTCs (CSV-CTCs). Disease-free survival (DFS) was assessed and used as an indicator of CTC phenotype-related prognosis. Univariate and multivariate Cox regression analyses were made to identify risk factors, and nomogram models were employed for prognostic prediction. A total of 82 patients were enrolled, with a CTC detection rate of 86.6%. Among the detected CTCs, 60% were CSV-CTCs. The CSV-CTC count showed a positive correlation with the T-stage, the M-stage, and the location of the primary tumor (P = 0.01, P = 0.014, and P = 0.01, respectively). Kaplan-Meier survival analysis revealed that CSV-CTCs were associated with worse DFS in patients receiving first-line oxaliplatin chemotherapy (hazard ratio (HR) = 3.78, 95% CI 1.55-9.26, p = 0.04). When the cut-off value of the CSV-CTC count was 3, the optimal prognostic prediction was achieved. Compound models considering CSV-CTCs, TNM staging, the site of the primary tumor and the Ras gene status yielded the best results in both the receiver operating characteristic (ROC) analysis and the decision curve analysis (DCA). This study indicates that CSV-CTCs predominate in CTCs of CRC patients, and a count of CSV-CTCs ≥ 3 is an independent risk factor for worse prognosis.

Targeting signaling pathways in osteosarcoma: Mechanisms and clinical studies

Osteosarcoma (OS) is a highly prevalent bone malignancy among adolescents, accounting for 40% of all primary malignant bone tumors. Neoadjuvant chemotherapy combined with limb-preserving surgery has effectively reduced patient disability and mortality, but pulmonary metastases and OS cells' resistance to chemotherapeutic agents are pressing challenges in the clinical management of OS. There has been an urgent need to identify new biomarkers for OS to develop specific targeted therapies. Recently, the continued advancements in genomic analysis have contributed to the identification of clinically significant molecular biomarkers for diagnosing OS, acting as therapeutic targets, and predicting prognosis. Additionally, the contemporary molecular classifications have revealed that the signaling pathways, including Wnt/β-catenin, PI3K/AKT/mTOR, JAK/STAT3, Hippo, Notch, PD-1/PD-L1, MAPK, and NF-κB, have an integral role in OS onset, progression, metastasis, and treatment response. These molecular classifications and biological markers have created new avenues for more accurate OS diagnosis and relevant treatment. We herein present a review of the recent findings for the modulatory role of signaling pathways as possible biological markers and treatment targets for OS. This review also discusses current OS therapeutic approaches, including signaling pathway-based therapies developed over the past decade. Additionally, the review covers the signaling targets involved in the curative effects of traditional Chinese medicines in the context of expression regulation of relevant genes and proteins through the signaling pathways to inhibit OS cell growth. These findings are expected to provide directions for integrating genomic, molecular, and clinical profiles to enhance OS diagnosis and treatment.

Platelets in the tumor microenvironment and their biological effects on cancer hallmarks

The interplay between platelets and tumors has long been studied. It has been widely accepted that platelets could promote tumor metastasis. However, the precise interactions between platelets and tumor cells have not been thoroughly investigated. Although platelets may play complex roles in multiple steps of tumor development, most studies focus on the platelets in the circulation of tumor patients. Platelets in the primary tumor microenvironment, in addition to platelets in the circulation during tumor cell dissemination, have recently been studied. Their effects on tumor biology are gradually figured out. According to updated cancer hallmarks, we reviewed the biological effects of platelets on tumors, including regulating tumor proliferation and growth, promoting cancer invasion and metastasis, inducing vasculature, avoiding immune destruction, and mediating tumor metabolism and inflammation.

ADAM19 and TUBB1 Correlate with Tumor Infiltrating Immune Cells and Predicts Prognosis in Osteosarcoma

BACKGROUND

Osteosarcoma is the most common type of primary malignant bone tumor.

INTRODUCTION

This study aimed to explore potential key prognostic genes and their roles in osteosarcoma.

METHODS

Three microarray datasets for osteosarcoma were downloaded from the GEO database. Differentially expressed genes (DEGs) were screened by the Limma package. Functional enrichment analysis was performed based on DAVID, GeneMANIA, and Metascape databases. Prognostic value of DEGs was elevated by survival analysis. CIBERSORT was used to assess the infiltrating abundance of 22 immune cells, followed by the Pearson correlation analysis between immune cells and prognosis-related genes. Gene set enrichment analysis and drug-gene interactions prediction were performed for prognosis-related genes.

RESULTS

A total of 8 common up-regulated DEGs and 13 common down-regulated DEGs were screened in the GSE36001 and GSE56001 datasets. Enrichment analysis showed these DEGs were implicated in platelet activation, SMAD protein phosphorylation, lymphocyte/leukocyte/T cells activation, and cell migration. Survival analysis indicated that elevated expression of ADAM19 and TUBB1 were associated with a favorable prognosis. CIBERSORT algorithm revealed the higher infiltrating level of CD8 T cells, macrophages M0, and M2 in osteosarcoma. ADAM19 expression positively correlated with naïve B cells and negatively correlated with activated dendritic cells infiltrating abundance. TUBB1 expression positively correlated with gamma delta T cells while negatively correlated with helper follicular T cells infiltrating abundance. A total of 56 drugs were found to target TUBB1.

CONCLUSION

ADAM19 and TUBB1 could be prognostic biomarkers in osteosarcoma. Both their expression correlates with tumor infiltrating immune cells. TUBB1 was a multi-drug target that might be a therapeutic target in osteosarcoma.

Receptor Tyrosine Kinase Inhibitors for the Treatment of Recurrent and Unresectable Bone Sarcomas

Bone sarcomas are a heterogeneous group of rare tumors with a predominance in the young population. Few options of systemic treatment are available once they become unresectable and resistant to conventional chemotherapy. A better knowledge of the key role that tyrosine kinase receptors (VEGFR, RET, MET, AXL, PDGFR, KIT, FGFR, IGF-1R) may play in the pathogenesis of these tumors has led to the development of multi-target inhibitors (TKIs) that are progressively being incorporated into our therapeutic arsenal. Osteosarcoma (OS) is the most frequent primary bone tumor and several TKIs have demonstrated clinical benefit in phase II clinical trials (cabozantinib, regorafenib, apatinib, sorafenib, and lenvatinib). Although the development of TKIs for other primary bone tumors is less advanced, preclinical data and early trials have begun to show their potential benefit in advanced Ewing sarcoma (ES) and rarer bone tumors (chondrosarcoma, chordoma, giant cell tumor of bone, and undifferentiated pleomorphic sarcoma). Previous reviews have mainly provided information on TKIs for OS and ES. We aim to summarize the existing knowledge regarding the use of TKIs in all bone sarcomas including the most recent studies as well as the potential synergistic effects of their combination with other systemic therapies.

Origin and Therapies of Osteosarcoma

Simple Summary

Osteosarcoma is the most common malignant bone tumor in children, with a 5-year survival rate ranging from 70% to 20% depending on the aggressiveness of the disease. The current treatments have not evolved over the past four decades due in part to the genetic complexity of the disease and its heterogeneity. This review will summarize the current knowledge of OS origin, diagnosis and therapies.

Abstract

Osteosarcoma (OS) is the most frequent primary bone tumor, mainly affecting children and young adults. Despite therapeutic advances, the 5-year survival rate is 70% but drastically decreases to 20–30% for poor responders to therapies or for patients with metastasis. No real evolution of the survival rates has been observed for four decades, explained by poor knowledge of the origin, difficulties related to diagnosis and the lack of targeted therapies for this pediatric tumor. This review will describe a non-exhaustive overview of osteosarcoma disease from a clinical and biological point of view, describing the origin, diagnosis and therapies.

Targeting Podoplanin for the Treatment of Osteosarcoma

PURPOSE

Osteosarcoma, the most common bone malignancy in children, has a poor prognosis, especially when the tumor metastasizes to the lungs. Therefore, novel therapeutic strategies targeting both proliferation and metastasis of osteosarcoma are required. Podoplanin (PDPN) is expressed by various tumors and is associated with tumor-induced platelet activation via its interaction with C-type lectin-like receptor 2 (CLEC-2) on platelets. We previously found that PDPN contributed to osteosarcoma growth and metastasis through platelet activation; thus, in this study, we developed an anti-PDPN humanized antibody and evaluated its effect on osteosarcoma growth and metastasis.

EXPERIMENTAL DESIGN

Nine osteosarcoma cell lines and two osteosarcoma patient-derived cells were collected, and we evaluated the efficacy of the anti-DPN-neutralizing antibody PG4D2 and the humanized anti-PDPN antibody AP201, which had IgG4 framework region. The antitumor and antimetastasis effect of PG4D2 and AP201 were examined in vitro and in vivo. In addition, growth signaling by the interaction between PDPN and CLEC-2 was analyzed using phospho-RTK (receptor tyrosine kinase) array, growth assay, or immunoblot analysis under the supression of RTKs by knockout and inhibitor treatment.

RESULTS

We observed that PG4D2 treatment significantly suppressed tumor growth and pulmonary metastasis in osteosarcoma xenograft models highly expressing PDPN. The contribution of PDGFR activation by activated platelet releasates to osteosarcoma cell proliferation was confirmed, and the humanized antibody, AP201, suppressed in vivo osteosarcoma growth and metastasis without significant adverse events.

CONCLUSIONS

Targeting PDPN with a neutralizing antibody against PDPN-CLEC-2 without antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity is a novel therapeutic strategy for PDPN-positive osteosarcoma.

Beyond Hemostasis: Platelet Innate Immune Interactions and Thromboinflammation

There is accumulating evidence that platelets play roles beyond their traditional functions in thrombosis and hemostasis, e.g., in inflammatory processes, infection and cancer, and that they interact, stimulate and regulate cells of the innate immune system such as neutrophils, monocytes and macrophages. In this review, we will focus on platelet activation in hemostatic and inflammatory processes, as well as platelet interactions with neutrophils and monocytes/macrophages. We take a closer look at the contributions of major platelet receptors GPIb, α_IIbβ₃, TLT-1, CLEC-2 and Toll-like receptors (TLRs) as well as secretions from platelet granules on platelet-neutrophil aggregate and neutrophil extracellular trap (NET) formation in atherosclerosis, transfusion-related acute lung injury (TRALI) and COVID-19. Further, we will address platelet-monocyte and macrophage interactions during cancer metastasis, infection, sepsis and platelet clearance.

Tetramethylpyrazine Retards the Progression and Fibrogenesis of Endometriosis

The development of more efficacious, non-hormonal therapeutics for endometriosis is still an unmet medical need begging to be fulfilled. Growing evidence indicates that endometriotic lesions are wounds undergoing repeated tissue injury and repair, and, as such, platelets play an important role in lesional progression. Tetramethylpyrazine (TMP), a compound derived from a herb that has been used for thousands of years to combat “blood stasis” in traditional Chinese medicine, is a prescription drug in China for the treatment of cerebrovascular disorders. We tested the hypothesis that TMP can decelerate lesional progression through arresting epithelial-mesenchymal transition (EMT), fibroblast-to-myofibroblast transdifferentiation (FMT), and fibrogenesis. We found in our in vitro experiments that TMP treatment suppresses platelet-induced EMT, FMT, cellular contractility, and collagen production in a concentration-dependent manner. We also showed that in a mouse model of endometriosis, treatment with TMP significantly reduced lesion weight and the extent of lesional fibrosis and improved hyperalgesia, mostly likely through the reduction of lesional aggregation of platelets and the lesional expression of markers of EMT, FMT, and fibrogenesis. In light of our results and in view of its excellent safety profiles, TMP appears to be a promising drug candidate for treating endometriosis.

The Effect of Terpenoid Natural Chinese Medicine Molecular Compound on Lung Cancer Treatment

Among all malignant tumors in the whole universe, the incidence and mortality of lung cancer disease rank first. Especially in the past few years, the occurrence of lung cancer in the urban population has continued to increase, which seriously threatens the lives and health of people. Among the many treatments for lung cancer, chemotherapy is the best one, but traditional chemotherapy has low specificity and drug resistance. To address the above issue, this study reviews the five biological pathways that common terpenoid compounds in medicinal plants interfere with the occurrence and development of lung cancer: cell proliferation, cell apoptosis, cell autophagy, cell invasion, metastasis, and immune mechanism regulation. In addition, the mechanism of the terpenoid natural traditional Chinese medicine monomer compound combined with Western medicine in the multipathway antilung cancer is summarized.

Cancer-Cell-Derived IgG and Its Potential Role in Tumor Development

Human immunoglobulin G (IgG) is the primary component of the human serum antibody fraction, representing about 75% of the immunoglobulins and 10-20% of the total circulating plasma proteins. Generally, IgG sequences are highly conserved, yet the four subclasses, IgG1, IgG2, IgG3, and IgG4, differ in their physiological effector functions by binding to different IgG-Fc receptors (FcγR). Thus, despite a similarity of about 90% on the amino acid level, each subclass possesses a unique manner of antigen binding and immune complex formation. Triggering FcγR-expressing cells results in a wide range of responses, including phagocytosis, antibody-dependent cell-mediated cytotoxicity, and complement activation. Textbook knowledge implies that only B lymphocytes are capable of producing antibodies, which recognize specific antigenic structures derived from pathogens and infected endogenous or tumorigenic cells. Here, we review recent discoveries, including our own observations, about misplaced IgG expression in tumor cells. Various studies described the presence of IgG in tumor cells using immunohistology and established correlations between high antibody levels and promotion of cancer cell proliferation, invasion, and poor clinical prognosis for the respective tumor patients. Furthermore, blocking tumor-cell-derived IgG inhibited tumor cells. Tumor-cell-derived IgG might impede antigen-dependent cellular cytotoxicity by binding antigens while, at the same time, lacking the capacity for complement activation. These findings recommend tumor-cell-derived IgG as a potential therapeutic target. The observed uniqueness of Ig heavy chains expressed by tumor cells, using PCR with V(D)J rearrangement specific primers, suggests that this specific part of IgG may additionally play a role as a potential tumor marker and, thus, also qualify for the neoantigen category.

Platelet-derived lysophosphatidic acid mediated LPAR1 activation as a therapeutic target for osteosarcoma metastasis

Osteosarcoma is the most common primary malignant bone cancer, with high rates of pulmonary metastasis. Osteosarcoma patients with pulmonary metastasis have worse prognosis than those with localized disease, leading to dramatically reduced survival rates. Therefore, understanding the biological characteristics of metastatic osteosarcoma and the molecular mechanisms of invasion and metastasis of osteosarcoma cells will lead to the development of innovative therapeutic intervention for advanced osteosarcoma. Here, we identified that osteosarcoma cells commonly exhibit high platelet activation-inducing characteristics, and molecules released from activated platelets promote the invasiveness of osteosarcoma cells. Given that heat-denatured platelet releasate maintained the ability to promote osteosarcoma invasion, we focused on heat-tolerant molecules, such as lipid mediators in the platelet releasate. Osteosarcoma-induced platelet activation leads to abundant lysophosphatidic acid (LPA) release. Exposure to LPA or platelet releasate induced morphological changes and increased invasiveness of osteosarcoma cells. By analyzing publicly available transcriptome datasets and our in-house osteosarcoma patient-derived xenograft tumors, we found that LPA receptor 1 (LPAR1) is notably upregulated in osteosarcoma. LPAR1 gene KO in osteosarcoma cells abolished the platelet-mediated osteosarcoma invasion in vitro and the formation of early pulmonary metastatic foci in experimental pulmonary metastasis models. Of note, the pharmacological inhibition of LPAR1 by the orally available LPAR1 antagonist, ONO-7300243, prevented pulmonary metastasis of osteosarcoma in the mouse models. These results indicate that the LPA-LPAR1 axis is essential for the osteosarcoma invasion and metastasis, and targeting LPAR1 would be a promising therapeutic intervention for advanced osteosarcoma.

Light-Responsive Micelles Loaded With Doxorubicin for Osteosarcoma Suppression

The enhancement of tumor targeting and cellular uptake of drugs are significant factors in maximizing anticancer therapy and minimizing the side effects of chemotherapeutic drugs. A key challenge remains to explore stimulus-responsive polymeric nanoparticles to achieve efficient drug delivery. In this study, doxorubicin conjugated polymer (Poly-Dox) with light-responsiveness was synthesized, which can self-assemble to form polymeric micelles (Poly-Dox-M) in water. As an inert structure, the polyethylene glycol (PEG) can shield the adsorption of protein and avoid becoming a protein crown in the blood circulation, improving the tumor targeting of drugs and reducing the cardiotoxicity of doxorubicin (Dox). Besides, after ultraviolet irradiation, the amide bond connecting Dox with PEG can be broken, which induced the responsive detachment of PEG and enhanced cellular uptake of Dox. Notably, the results of immunohistochemistry in vivo showed that Poly-Dox-M had no significant damage to normal organs. Meanwhile, they showed efficient tumor-suppressive effects. This nano-delivery system with the light-responsive feature might hold great promises for the targeted therapy for osteosarcoma.

Genomic and Transcriptomic Characterization of Canine Osteosarcoma Cell Lines: A Valuable Resource in Translational Medicine

Osteosarcoma (OSA) represents the most common primary bone tumor in dogs and is characterized by a highly aggressive behavior. Cell lines represent one of the most suitable and reproducible pre-clinical models, and therefore the knowledge of their molecular landscape is mandatory to investigate oncogenic mechanisms and drug response. The present study aims at determining variants, putative driver genes, and gene expression aberrations by integrating whole-exome and RNA sequencing. For this purpose, eight canine OSA cell lines and one matched pair of primary tumor and normal tissue were analyzed. Overall, cell lines revealed a mean tumor mutational burden of 9.6 mutations/Mb (range 3.9–16.8). Several known oncogenes and tumor suppressor genes, such as ALK, MYC, and MET, were prioritized as having a likely role in canine OSA. Mutations in eight genes, previously described as human OSA drivers and including TP53, PTCH1, MED12, and PI3KCA, were retrieved in our cell lines. When variants were cross-referenced with human OSA driver mutations, the E273K mutation of TP53 was identified in the Wall cell line and tumor sample. The transcriptome profiling detected two possible p53 inactivation mechanisms in the Wall cell line on the one hand, and in D17 and D22 on the other. Moreover, MET overexpression, potentially leading to MAPK/ERK pathway activation, was observed in D17 and D22 cell lines. In conclusion, our data provide the molecular characterization of a large number of canine OSA cell lines, allowing future investigations on potential therapeutic targets and associated biomarkers. Notably, the Wall cell line represents a valuable model to empower prospective in vitro studies both in human and in dogs, since the TP53 driver mutation was maintained during cell line establishment and was widely reported as a mutation hotspot in several human cancers.

Platelets, immune cells and the coagulation cascade; friend or foe of the circulating tumour cell?

Cancer cells that transit from primary tumours into the circulatory system are known as circulating tumour cells (CTCs). These cancer cells have unique phenotypic and genotypic characteristics which allow them to survive within the circulation, subsequently extravasate and metastasise. CTCs have emerged as a useful diagnostic tool using "liquid biopsies" to report on the metastatic potential of cancers. However, CTCs by their nature interact with components of the blood circulatory system on a constant basis, influencing both their physical and morphological characteristics as well as metastatic capabilities. These properties and the associated molecular profile may provide critical diagnostic and prognostic capabilities in the clinic. Platelets interact with CTCs within minutes of their dissemination and are crucial in the formation of the initial metastatic niche. Platelets and coagulation proteins also alter the fate of a CTC by influencing EMT, promoting pro-survival signalling and aiding in evading immune cell destruction. CTCs have the capacity to directly hijack immune cells and utilise them to aid in CTC metastatic seeding processes. The disruption of CTC clusters may also offer a strategy for the treatment of advance staged cancers. Therapeutic disruption of these heterotypical interactions as well as direct CTC targeting hold great promise, especially with the advent of new immunotherapies and personalised medicines. Understanding the molecular role that platelets, immune cells and the coagulation cascade play in CTC biology will allow us to identify and characterise the most clinically relevant CTCs from patients. This will subsequently advance the clinical utility of CTCs in cancer diagnosis/prognosis.

Cold Atmospheric Plasma: A New Strategy Based Primarily on Oxidative Stress for Osteosarcoma Therapy

Osteosarcoma is the most common primary bone tumor, and its first line of treatment presents a high failure rate. The 5-year survival for children and teenagers with osteosarcoma is 70% (if diagnosed before it has metastasized) or 20% (if spread at the time of diagnosis), stressing the need for novel therapies. Recently, cold atmospheric plasmas (ionized gases consisting of UV-Vis radiation, electromagnetic fields and a great variety of reactive species) and plasma-treated liquids have been shown to have the potential to selectively eliminate cancer cells in different tumors through an oxidative stress-dependent mechanism. In this work, we review the current state of the art in cold plasma therapy for osteosarcoma. Specifically, we emphasize the mechanisms unveiled thus far regarding the action of plasmas on osteosarcoma. Finally, we review current and potential future approaches, emphasizing the most critical challenges for the development of osteosarcoma therapies based on this emerging technique.

Platelet supernatant with longer storage inhibits tumor cell growth

BACKGROUND

Platelet transfusion is an essential supportive treatment for cancer patients. Platelets promote metastasis, but their role in tumor growth remains controversial. This study aimed to explore the impact of apheresis platelet supernatants of different storage periods on tumor cell growth, optimize blood transfusion timing, and provide a reference for reducing the risks of platelet transfusion in cancer patients.

METHODS

Eight human tumor cell lines, including HepG2, HuH7, SMMC-7721, HeLa, HCT116, MCF-7, K562, and Jurkat were cultured. After culturing the platelet supernatant of days 0, 3, 5, and 7 with tumor cells, counting kit 8 (CCK-8), scratch assay, and propidium iodide (PI) were used to evaluate cell proliferation, migration, and cell cycle, respectively. Metabolomics analysis was performed to confirm whether differential metabolites produced during platelet storage are involved in the cancer pathway.

RESULTS

Platelet supernatants inhibit tumor cell proliferation by blocking the cell cycle at the G0/G1 phase, and their inhibitory effect increases with storage time. However, platelets promote tumor cells to form cytoskeletal connections, thereby promoting migration. Besides, metabonomics analysis of platelet supernatants during different storage periods reveals that upregulated differential metabolites are involved in cancer-related pathways.

CONCLUSION

The role of platelets in tumor cells is two-sided, that is, they inhibit proliferation while promoting migration. Therefore, additional in-depth studies on the appropriate timing of platelet transfusion are necessary.

Identification of CDCA8, DSN1 and BIRC5 in Regulating Cell Cycle and Apoptosis in Osteosarcoma Using Bioinformatics and Cell Biology

Introduction:

Osteosarcoma is the most common primary tumor of bone, although some molecular markers have been identified, the detailed molecular mechanisms underlying osteosarcoma are currently not fully understood. In the present study, we attempted to identify the potential key genes and pathways in osteosarcoma using bioinformatics analysis.

Methods:

GSE14359 was downloaded from the GEO database, and analyzed using Limma package. Gene Ontology and pathway enrichment analyses of the DEGs were performed in the DAVID database, followed by the construction of a protein–protein interaction (PPI) network with software Cytoscape, subnetwork modules were subsequently identified and analyzed, and further validation in human osteosarcoma tissues and osteosarcoma cells line was performed.

Results:

964 Differentially expressed genes (DEGs) identified, of which 222 were up-regulated and 742 were down-regulated. Among them, 10 genes (including BIRC5, MAD2L1, Bub1, DSN1, SPC24, CDCA8, STAG2, CENPA, MLF1IP and Mis12) were identified as hub genes and they were mainly enriched in pathways, including mRNA surveillance, RNA transport and PI3K-Akt signaling pathways. Further validation indicated 6 gene (DSN1, BIRC5, CDCA8, MLF1IP, MAD2L1 and SPC24) is highly expressed in osteosarcoma tissues. Among them, CDCA8, DSN1 and BIRC5 significantly promoted the proliferation of osteosarcoma cells in vitro. In terms of mechanism, DSN1 and CDCA8 were mainly involved in cell cycle regulation, while BIRC5 was mainly involved in the regulation of apoptosis pathway.

Conclusions:

We identified some key genes and pathways in osteosarcoma, which might be used as molecular targets or diagnostic biomarker for the diagnosis and therapy of osteosarcoma.

Mesothelial Cells Participate in Endometriosis Fibrogenesis Through Platelet-Induced Mesothelial-Mesenchymal Transition

CONTEXT

While fibrosis in endometriosis has recently loomed prominently, the sources of myofibroblasts, the principal effector cell in fibrotic diseases, remain largely obscure. Mesothelial cells (MCs) can be converted into myofibroblasts through mesothelial-mesenchymal transition (MMT) in many fibrotic diseases and adhesion.

OBJECTIVE

To evaluate whether MCs contribute to the progression and fibrogenesis in endometriosis through MMT.

SETTING, DESIGN, PATIENTS, INTERVENTION, AND MAIN OUTCOME MEASURES

Dual immunofluorescence staining and immunohistochemistry using antibodies against calretinin, Wilms' tumor-1 (WT-1), and α-smooth muscle actin (α-SMA) were performed on lesion samples from 30 patients each with ovarian endometrioma (OE) and deep endometriosis (DE), and 30 normal endometrial (NE) tissue samples. Human pleural and peritoneal MCs were co-cultured with activated platelets or control medium with and without neutralization of transforming growth factor β1 (TGF-β1) and/or platelet-derived growth factor receptor (PDGFR) and their morphology, proliferation, and expression levels of genes and proteins known to be involved in MMT were evaluated, along with their migratory and invasive propensity, contractility, and collagen production.

RESULTS

The number of calretinin/WT-1 and α-SMA dual-positive fibroblasts in OE/DE lesions was significantly higher than NE samples. The extent of lesional fibrosis correlated positively with the lesional α-SMA staining levels. Human MCs co-cultured with activated platelets acquire a morphology suggestive of MMT, concomitant with increased proliferation, loss of calretinin expression, and marked increase in expression of mesenchymal markers. These changes coincided with functional differentiation as reflected by increased migratory and invasive capacity, contractility, and collagen production. Neutralization of TGF-β1 and PDGFR signaling abolished platelet-induced MMT in MCs.

CONCLUSIONS

MCs contribute to lesional progression and fibrosis through platelet-induced MMT.

Role of Platelet C-Type Lectin-Like Receptor 2 in Promoting Lung Metastasis in Osteosarcoma

The overall prognosis of patients with sarcoma-based cancers has changed little in the last 20 years. There is an urgent need to investigate the metastatic potential of these tumors and to develop anti-metastatic drugs. It is becoming increasingly clear that platelets play an important role in the establishment of metastasis of carcinoma cells and could be a useful therapeutic target for patients with carcinoma. However, little is known about the role of platelets in sarcoma progression. Here, we investigated how osteosarcoma progression relates to platelet function to explore the possibility of anti-platelet therapy. We found that, similar to carcinoma cells, podoplanin (also known as Aggrus)-positive osteosarcoma cells induce platelet aggregation and activation. Administration of anti-glycoprotein Ibα (GPIbα, also known as CD42b) antibody reduced the lung metastasis of osteosarcoma. The supernatant from platelets cocultured with osteosarcoma cells contained several growth factors and promoted proliferation, invasiveness, and sphere formation of osteosarcoma cells in vitro. In addition, the development of lung metastasis was highly dependent on direct interaction between osteosarcoma cells and platelets. To explore the therapeutic target, we focused on the interactions between podoplanin on osteosarcoma and C-type lectin-like receptor (CLEC)-2 on platelets. The administration of a depleting antibody against CLEC-2 efficiently suppressed osteosarcoma metastasis into the lung. We also analyzed clinical data from patient samples at primary and metastatic sites. Although GPIbα expression was similar between the two sites, there was a significant increase in podoplanin at the metastatic site compared to that in the primary site, and the level of podoplanin expression in the primary site correlated with patient prognosis. These findings suggest that blockade of interactions between platelets CLEC-2 and osteosarcoma podoplanin represent the most promising therapeutic strategy for preventing the lung metastasis of osteosarcoma. © 2020 American Society for Bone and Mineral Research.

Receptor Tyrosine Kinases in Osteosarcoma Treatment: Which Is the Key Target?

Recent clinical trials have shown several multi-target tyrosine kinase inhibitors (TKIs) to be effective in the treatment of osteosarcoma. However, these TKIs have a number of targets, and it is yet unclear which of these targets has a key role in osteosarcoma treatment. In this review, we first summarize the TKIs that were studied in clinical trials registered on ClinicalTrials.gov. Further, we compare and discuss the targets of these TKIs. We found that TKIs with promising therapeutic effect for osteosarcoma include apatinib, cabozantinib, lenvatinib, regorafenib, and sorafenib. The key targets for osteosarcoma treatment may include VEGFRs and RET. The receptor tyrosine kinases (RTKs) MET, IGF-1R, AXL, PDGFRs, KIT, and FGFRs might be relevant but unimportant targets for osteosarcoma treatment. Inhibition of one type of RTK for the treatment of osteosarcoma is not effective. It is necessary to inhibit several relevant RTKs simultaneously to achieve a breakthrough in osteosarcoma treatment. This review provides comprehensive information on TKI targets relevant in osteosarcoma treatment, and it will be useful for further research in this field.

Innate immune receptors in platelets and platelet-leukocyte interactions

Platelets are chief cells in hemostasis. Apart from their hemostatic roles, platelets are major inflammatory effector cells that can influence both innate and adaptive immune responses. Activated platelets have thromboinflammatory functions linking hemostatic and immune responses in several physiological and pathological conditions. Among many ways in which platelets exert these functions, platelet expression of pattern recognition receptors (PRRs), including TLR, Nod-like receptor, and C-type lectin receptor families, plays major roles in sensing and responding to pathogen-associated or damage-associated molecular patterns (PAMPs and DAMPs, respectively). In this review, an increasing body of evidence is compiled showing the participation of platelet innate immune receptors, including PRRs, in infectious diseases, sterile inflammation, and cancer. How platelet recognition of endogenous DAMPs participates in sterile inflammatory diseases and thrombosis is discussed. In addition, platelet recognition of both PAMPs and DAMPs initiates platelet-mediated inflammation and vascular thrombosis in infectious diseases, including viral, bacterial, and parasite infections. The study also focuses on the involvement of innate immune receptors in platelet activation during cancer, and their contribution to tumor microenvironment development and metastasis. Finally, how innate immune receptors participate in platelet communication with leukocytes, modulating leukocyte-mediated inflammation and immune functions, is highlighted. These cell communication processes, including platelet-induced release of neutrophil extracellular traps, platelet Ag presentation to T-cells and platelet modulation of monocyte cytokine secretion are discussed in the context of infectious and sterile diseases of major concern in human health, including cardiovascular diseases, dengue, HIV infection, sepsis, and cancer.

Down-regulation of PDGFRβ suppresses invasion and migration in osteosarcoma cells by influencing epithelial-mesenchymal transition

Osteosarcoma (OS) is the most common malignant bone tumor primarily influencing children and adults. Approximately one‐fifth of patients have micrometastasis in the lungs when OS is diagnosed. Platelet‐derived growth factor receptor (PDGFR) beta (PDGFRβ) is a subtype of PDGFR. PDGFRβ has been noted to be highly expressed in OS cell lines and patient specimens, and is associated with metastasis and poor prognosis of OS. However, mechanistic insights into the exact role of PDGFRβ in OS pathogenesis and development are still lacking. Here we assessed the effects of PDGFRβ on invasive and migratory abilities, such as the epithelial–mesenchymal transition and phosphatidylinositol 3‐kinase (PI3K), Akt and mammalian target of rapamycin (mTOR) pathways in HOS cells. Depleting PDGFRβ resulted in reduced migration of HOS cells in the small interfering RNA duplexes specific for the PDGFRβ group compared with the mock and scramble‐treated groups in Transwell invasion assays. Using wound‐healing assays, we demonstrate the rate of wound healing in the PDGF‐BB‐stimulated group was higher compared with the mock‐treated group. Western blot showed that down‐regulation of PDGFRβ decreased the expression of stromal phenotype markers and phosphorylation pathway proteins (PI3K, AKT and mTOR), but the epithelial phenotype marker was increased in HOS cells. Treating HOS cells with PDGF‐BB revealed a treatment time‐dependent increase of phosphorylated, but not total, PI3K, AKT and mTOR. Taken together, we suggest that PDGFRβ plays an important role in OS invasion, migration and epithelial–mesenchymal transition by influencing the PI3K, Akt and mTOR pathways, hence highlighting PDGFRβ as a potential therapeutic target for OS.

Extravasated platelet aggregation contributes to tumor progression via the accumulation of myeloid-derived suppressor cells in gastric cancer with peritoneal metastasis

Extravasated platelet aggregation (EPA) serves an important role in the cancer microenvironment during cancer progression, and has been demonstrated to interact with tumor cells in several types of cancer. EPA induces epithelial-mesenchymal transition (EMT) via transforming growth factor-β, and also recruits immunosuppressive cells, including regulatory T (Treg) cells and myeloid-derived suppressor cells (MDSCs). However, the role of EPA in gastric cancer with peritoneal metastasis remains unknown. The present study analyzed the association between EPA and prognosis in patients with gastric cancer with peritoneal metastasis. The present study evaluated 62 patients diagnosed with advanced gastric cancer with peritoneal metastasis between 2001 and 2016. EPA, EMT, Treg cells and MDSCs in peritoneal metastatic lesions were detected by immunohistochemical evaluation of CD42b, SNAIL, FOXP3 and CD33, respectively. CD42b expression was observed in 56.5% (35/62) of peritoneal metastatic lesions. CD42b expression in peritoneal metastatic lesions was associated with poor overall survival compared with lower frequencies (hazard ratio, 2.03; 95% confidence interval, 1.12–3.69; P=0.018). SNAIL, FOXP3 and CD33 expression were not associated with overall survival, but CD33 expression was markedly higher in CD42b-positive patients (P=0.022). These results indicated that EPA affects immunosuppression by recruiting MDSCs in the tumor microenvironment via the secretion of soluble factors, resulting in tumor progression. EPA may be a novel therapeutic target for gastric cancer with peritoneal metastasis.

Platelets induce endothelial-mesenchymal transition and subsequent fibrogenesis in endometriosis

RESEARCH QUESTION

Do endometriotic lesions undergo endothelial-mesenchymal transition (EndoMT)?

DESIGN

Lesion samples from 30 patients with ovarian endometriomas and deep endometriosis, and control endometrial tissue samples from 30 women without endometriosis, were analysed. In-vitro experimentation using the human umbilical vein endothelial cell (HUVEC) line were conducted. Immunofluorescence staining and immunohistochemistry analysis using antibodies against endothelial cell and mesenchymal cell markers were conducted. The HUVEC cells were co-cultured with activated platelets or control medium with and without neutralization of TGF-β1 PDGFR, or both. Their morphology, proliferation and expression levels of genes and proteins known to be involved in EndoMT were evaluated, along with their migratory and invasive propensity, contractility and collagen production capability.

RESULTS

The proportion of CD31 and FSP-1 dual-positive cells in FSP-1+ fibroblasts was 74.7% (±5.4%) in ovarian endometrioma lesions, significantly higher than that in deep endometriosis lesions (26.8% ± 26.0%; P = 5.7 × 10^-5), and was zero in normal endometrium. The extent of lesional fibrosis correlated positively with staining levels of the lesional mesenchymal markers FSP-1 and α-SMA (r = 0.91; P < 2.2 × 10^-16, r = 0.81; P = 5.8 × 10^-15, respectively). Human endothelial cells co-cultured with activated platelets acquire a morphology suggestive of EndoMT, concomitant with increased proliferation, loss of CD31 but marked increase in expression of mesenchymal markers. Morphological and gene and protein expression changes are accompanied by functional differentiation reflected by increased migratory and invasive capacity, contractility and collagen production. Neutralization of TGF-β1 and PDGFR signalling abolished platelet-induced EndoMT in human endothelial cells.

CONCLUSIONS

Multiple sources of myofibroblasts exist in endometriotic lesions, and implicates platelets, EndoMT, or both, as potential therapeutic targets for treating endometriosis.

Pretreatment inflammatory indexes as prognostic predictors for survival in osteosarcoma patients

Pretreatment inflammatory indexes including neutrophil-lymphocyte ratio (NLR), lymphocyte-monocyte ratio (LMR), platelet-lymphocyte ratio (PLR), and systemic immune-inflammation index (SII) are associated with poor outcomes in various malignant tumors, but their prognostic value in patients with osteosarcoma is poorly known. This was a retrospective study of patients with osteosarcoma treated between 01/2010 and 12/2013 at Chongqing University Cancer Hospital. Follow-up was calculated from the date of initial histological diagnosis to December 2018 or death or loss of follow-up. Receiver operating characteristic (ROC) analysis was used to determine the NLR, LMR, PLR, and SII cut-off values (low (L) vs. high (H)). The Kaplan-Meier method was used for survival analysis. Univariable and multivariable Cox analyses were performed to determine the independent prognostic factors. Patients with LNLR had better survival than those with HNLR (median, 38.0 vs. 13.0, P<0.001). Patients with LSII had better survival (26.0 vs. 10.0 months, P=0.001) than those with HSII. The areas under the curves for NLR, LMR, PLR, SII, and ALP were 0.761 (P<0.001), 0.683 (P=0.012), 0.697 (P=0.002), 0.653 (P=0.031), and 0.515 (P=0.837), respectively. In the univariable analyses, Enneking's stage, systemic chemotherapy, surgery, NLR, PLR, LMR, and SII were associated with overall survival (OS). The multivariable analysis showed that HNLR (HR=2.507; 95% CI=1.364-4.606; P=0.003) was independent unfavorable prognostic factors. This preliminary study suggests that NLR is associated with poor prognosis in osteosarcoma. NLR could be a potential prognostic marker of osteosarcoma.

Alantolactone suppresses human osteosarcoma through the PI3K/AKT signaling pathway

Osteosarcoma is the most common type of malignant bone cancer and results in cancer-related deaths among adolescents. Alantolactone (ALT) demonstrates antitumor properties in various diseases; however, its potential role in osteosarcoma is relatively unclear. The aim of the present study was to evaluate the effect of ALT on osteosarcoma. ALT significantly decreased the viability of U2OS and HOS osteosarcoma cell lines. Cells flow cytometry assay and Hoechst 33258 staining assay revealed that ALT significantly increased the proportion of apoptotic U2OS cells. In addition, wound healing and Transwell invasion assays demonstrated that the invasion and migration of osteosarcoma were markedly reduced upon ALT treatment. It was hypothesized that the antitumor functions of ALT are mediated through inhibition of the PI3K/AKT signaling pathway. In conclusion, the results of the present study confirmed the inhibition of ALT on osteosarcoma cells via downregulation of PI3K/AKT signaling pathways, suggesting ALT as a potential therapeutic candidate for osteosarcoma.

Osteomimetic matrix components alter cell migration and drug response in a 3D tumour-engineered osteosarcoma model

Osteosarcoma management continues to lack the appropriate prognostic tools to assign personalised treatment. This leaves non-responders to standard care vulnerable to recurring disease and pulmonary metastases. Developing 3D in vitro disease models to serve as a test bed for personalised treatment is a promising approach to address this issue. This study describes the generation of 3D osteosarcoma models termed "tumouroids", which are geometrically compartmentalised to reproduce the bone cancer mass and its surrounding. Although the tumour microenvironment impacts osteosarcoma in many ways, this model focussed on interrogating the influence of a biomimetic matrix on tumour cell behaviour. The 3D matrix was supplemented with the bone-marrow proteins laminin, fibronectin and NuOss® bone granules. This led to increased invasion of osteosarcoma cell aggregates from within the bone-like matrix into the surrounding acellular bone marrow-like ECM. The presence of bone granules also yielded an atypical molecular profile of osteosarcoma cells, suggesting malignant metabolic reprogramming. Changes include decreased MMP-9 (p < 0.05) and increased PTEN (p < 0.05), MCP-1 (p < 0.01) and MCT-4 (p < 0.05) gene expression. This complex 3D biomimetic composition also changed cellular responses to doxorubicin, a common chemotherapeutic agent used to treat osteosarcoma, and reproduced key issues of in vivo treatment like drug penetrance and doxorubicin-induced bone toxicity. This work highlights the importance of a biomimetic matrix in 3D osteosarcoma models for both basic and translational research. STATEMENT OF SIGNIFICANCE: This study describes the generation of 3D osteosarcoma models termed "tumouroids", which are geometrically compartmentalised to reproduce the bone cancer mass and its environment. Utilising this novel model, specific parameters of osteosarcoma growth and invasion were investigated. Osteosarcoma cell lines proliferate at a slower rate, exhibit malignant metabolic reprogramming, and respond to drug intervention at lower concentrations of doxorubicin hydrochloride in matrix-complex compared to basic tumouroids. As such, this study provides evidence that the tumour microenvironment impacts osteosarcoma in many ways. The osteosarcoma tumouroid described herein may form the basis of a personalised-medicine strategy, which will allow the testing of drug effectiveness similar to that used for antibiotic selection for pathogenic bacteria.

Effect of tumor microenvironment on pathogenesis of the head and neck squamous cell carcinoma: a systematic review

The tumor microenvironment (TME) is comprised of many different cell populations, such as cancer-associated fibroblasts and various infiltrating immune cells, and non-cell components of extracellular matrix. These crucial parts of the surrounding stroma can function as both positive and negative regulators of all hallmarks of cancer development, including evasion of apoptosis, induction of angiogenesis, deregulation of the energy metabolism, resistance to the immune detection and destruction, and activation of invasion and metastasis. This review represents a summary of recent studies focusing on describing these effects of microenvironment on initiation and progression of the head and neck squamous cell carcinoma, focusing on oral squamous cell carcinoma, since it is becoming clear that an investigation of differences in stromal composition of the head and neck squamous cell carcinoma microenvironment and their impact on cancer development and progression may help better understand the mechanisms behind different responses to therapy and help define possible targets for clinical intervention.

Three gold indicators for breast cancer prognosis: a case-control study with ROC analysis for novel ratios related to CBC with (ALP and LDH)

Science is still unable to develop a specific strategy for predicting breast cancer in humans. Several attempts are done to obtain the best and closest prognostic predictive biomarkers for breast cancer. The present study aimed to evaluate the impact of novel ratios calculated between the blood indices with CA15.3, alkaline phosphatase and lactate dehydrogenase as prognostic biomarkers in breast cancer. This study was conducted on two groups (Breast cancer Patients group in comparison to a control group who has no tumor family history). All the volunteers are subjected to the routine analysis included liver and kidney function tests, complete blood count with blood indices, tumor markers (CA15.3) assessment, alkaline phosphatase, and lactate dehydrogenase analysis. Thirty different ratios were calculated in the present research between blood indices and three inexpensive serum biomarkers; CA15.3, alkaline phosphatase and lactate dehydrogenase. Fifteen ratios of them were significant in breast cancer group than the control group. Three ratios (PDW/lymphocytes, MPV/lymphocytes, and ALP/RDW) of them gave a sensitivity of 100% with high specificity as indicators for breast cancer incidence. The correlation between significant ratios was very interesting. The more interesting was in the results of subgroup analysis which showed that the ALP/RDW ratio is more specific for pre-menopause while PDW/lymphocytes ratio is more specific for post-menopause. The ratios PDW/lymphocytes, MPV/lymphocytes, and ALP/RDW can be used as prognostic biomarkers in breast cancer patients. The interesting advantage in the results depends on the availability of these indicators in routine blood analysis and will not increase the cost of the diagnostic plan.

Cancer cell-derived immunoglobulin G activates platelets by binding to platelet FcγRIIa

Tumor-associated thrombosis is the second leading risk factor for cancer patient death, and platelets activity is abnormal in cancer patients. Discovering the mechanism of platelet activation and providing effective targets for therapy are urgently needed. Cancer cell- derived IgG has been reported to regulate development of tumors. However, studies on the functions of cancer cell-derived IgG are quite limited. Here we investigated the potential role of cancer cell-derived IgG in platelet activation. We detected the expression of CD62P on platelets by flow cytometry and analyzed platelet function by platelets aggregation and ATP release. The content of IgG in cancer cell supernatants was detected by enzyme-linked immune sorbent assay. The distribution of cancer-derived IgG in cancer cells was analyzed by immunofluorescence assay. Western blot was performed to quantify the relative expression of FcγRIIa, syk, PLCγ2. The interaction between cancer cell-derived IgG and platelet FcγRIIa was analyzed by co-immunoprecipitation. The results showed that higher levels of CD62P were observed in cancer patients' platelets compared with that of healthy volunteers. Cancer cell culture supernatants increased platelet CD62P and PAC-1 expression, sensitive platelet aggregation and ATP release in response to agonists, while blocking FcγRIIa or knocking down IgG reduced the activation of platelets. Coimmunoprecipitation results showed that cancer cell-derived IgG interacted directly with platelet FcγRIIa. In addition, platelet FcγRIIa was highly expressed in liver cancer patients. In summary, cancer cell-derived IgG interacted directly with FcγRIIa and activated platelets; targeting this interaction may be an approach to prevent and treat tumor-associated thrombosis.

Platelet-Derived TGF-β Induces Tissue Factor Expression via the Smad3 Pathway in Osteosarcoma Cells

Over the last three decades, the prognosis of osteosarcoma has remained unchanged; the prognosis for patients with lung metastasis is still poor, and the development of new treatments is urgently required. We previously showed that aggressive osteosarcoma cells express more tissue factor (TF) and demonstrate enhanced extrinsic pathway capacity. Furthermore, tumor growth can be suppressed with the anticoagulant low molecular weight heparin. However, the molecular mechanisms underlying TF regulation are still unclear. Here, we report that transforming growth factor-β (TGF-β) upregulates TF, which can occur via activated platelets. TF was found to be expressed on osteosarcoma cell surfaces, which mediated the production of Xa and thrombin. TF induction by TGF-β was observed in several osteosarcoma cells, and especially in MG 63 cells. Both TF expression by TGF-β and extrinsic pathway activity through TF were rapidly increased. This reaction was inhibited by a TGF-β type I receptor inhibitor and TGF-β neutralizing antibody. Although TGF-β was found to phosphorylate both Smad2 and Smad3, their roles were markedly disparate. Surprisingly, Smad2 knockdown resulted in no inhibitory effect, whereas Smad3 knockdown completely suppressed TGF-β-induced TF expression. Next, data suggested that platelets were the source of TGF-β. We confirmed that thrombin-activated platelets and osteosarcoma cells could release TGF-β, and that platelet-derived TGF-β could induce TF expression. These processes were also inhibited by a TGF-β type I receptor inhibitor and Smad3 knockdown. Moreover, CD42b, TF, TGF-β, Smad2/3, and p-Smad2/3 were also detected in a biopsy sample from an osteosarcoma patient. Collectively, these finding suggested that the interaction between osteosarcoma cells and platelets, via thrombin and TGF-β, results in a continuous cycle, and that anti-platelet or anti-TGF-β therapy could be a promising tool for disease treatment. © 2018 American Society for Bone and Mineral Research.

Role of platelets and platelet receptors in cancer metastasis

The interaction of tumor cells with platelets is a prerequisite for successful hematogenous metastatic dissemination. Upon tumor cell arrival in the blood, tumor cells immediately activate platelets to form a permissive microenvironment. Platelets protect tumor cells from shear forces and assault of NK cells, recruit myeloid cells by secretion of chemokines, and mediate an arrest of the tumor cell platelet embolus at the vascular wall. Subsequently, platelet-derived growth factors confer a mesenchymal-like phenotype to tumor cells and open the capillary endothelium to expedite extravasation in distant organs. Finally, platelet-secreted growth factors stimulate tumor cell proliferation to micrometastatic foci. This review provides a synopsis on the current literature on platelet-mediated effects in cancer metastasis and particularly focuses on platelet adhesion receptors and their role in metastasis. Immunoreceptor tyrosine-based activation motif (ITAM) and hemi ITAM (hemITAM) comprising receptors, especially, glycoprotein VI (GPVI), FcγRIIa, and C-type lectin-like-2 receptor (CLEC-2) are turned in the spotlight since several new mechanisms and contributions to metastasis have been attributed to this family of platelet receptors in the last years.

Platelet-activating factor podoplanin: from discovery to drug development

Tumor cell-induced platelet aggregation facilitates hematogenous metastasis by promoting tumor embolization, preventing immunological assaults and shear stress, and the platelet-releasing growth factors support tumor growth and invasion. Podoplanin, also known as Aggrus, is a type I transmembrane mucin-like glycoprotein and is expressed on wide range of tumor cells. Podoplanin has a role in platelet aggregation and metastasis formation through the binding to its platelet receptor, C-type lectin-like receptor 2 (CLEC-2). The podoplanin research was originally started from the cloning of highly metastatic NL-17 subclone from mouse colon 26 cancer cell line and from the establishment of 8F11 monoclonal antibody (mAb) that could neutralize NL-17-induced platelet aggregation and hematogenous metastasis. Later on, podoplanin was identified as the antigen of 8F11 mAb, and its ectopic expression brought to cells the platelet-aggregating abilities and hematogenous metastasis phenotypes. From the 8F11 mAb recognition epitopes, podoplanin is found to contain tandemly repeated, highly conserved motifs, designated platelet aggregation-stimulating (PLAG) domains. Series of analyses using the cells expressing the mutants and the established neutralizing anti-podoplanin mAbs uncovered that both PLAG3 and PLAG4 domains are associated with the CLEC-2 binding. The neutralizing mAbs targeting PLAG3 or PLAG4 could suppress podoplanin-induced platelet aggregation and hematogenous metastasis through inhibiting the podoplanin–CLEC-2 binding. Therefore, these domains are certainly functional in podoplanin-mediated metastasis through its platelet-aggregating activity. This review summarizes the platelet functions in metastasis formation, the role of platelet aggregation-inducing factor podoplanin in pathological and physiological situations, and the possibility to develop podoplanin-targeting drugs in the future.

Logistic regression analysis for the identification of the metastasis-associated signaling pathways of osteosarcoma

Osteosarcoma (OS) is the most common histological type of primary bone cancer. The present study was designed to identify the key genes and signaling pathways involved in the metastasis of OS. Microarray data of GSE39055 were downloaded from the Gene Expression Omnibus database, which included 19 OS biopsy specimens before metastasis (control group) and 18 OS biopsy specimens after metastasis (case group). After the differentially expressed genes (DEGs) were identified using the Linear Models for Microarray Analysis package, hierarchical clustering analysis and unsupervised clustering analysis were performed separately, using orange software and the self-organization map method. Based upon the Database for Annotation, Visualization and Integrated Discovery tool and Cytoscape software, enrichment analysis and protein-protein interaction (PPI) network analysis were conducted, respectively. After function deviation scores were calculated for the significantly enriched terms, hierarchical clustering analysis was performed using Cluster 3.0 software. Furthermore, logistic regression analysis was used to identify the terms that were significantly different. Those terms that were significantly different were validated using other independent datasets. There were 840 DEGs in the case group. There were various interactions in the PPI network [including intercellular adhesion molecule-1 (ICAM1), transforming growth factor β1 (TGFB1), TGFB1-platelet-derived growth factor subunit B (PDGFB) and PDGFB-platelet-derived growth factor receptor-β (PDGFRB)]. Regulation of cell migration, nucleotide excision repair, the Wnt signaling pathway and cell migration were identified as the terms that were significantly different. ICAM1, PDGFB, PDGFRB and TGFB1 were identified to be enriched in cell migration and regulation of cell migration. Nucleotide excision repair and the Wnt signaling pathway were the metastasis-associated pathways of OS. In addition, ICAM1, PDGFB, PDGFRB and TGFB1, which were involved in cell migration and regulation of cell migration may affect the metastasis of OS.

The prognostic impact of the platelet distribution width-to-platelet count ratio in patients with breast cancer

Activated platelets promote tumor cell growth, angiogenesis, and invasion. Platelet activity can be inferred by platelet volume indices (PVIs), which include platelet distribution width (PDW), mean platelet volume (MPV), platelet distribution width-to-platelet count ratio (PDW/P), and mean platelet volume-to-platelet count ratio. Platelets and platelet-related markers, such as the platelet-to-lymphocyte ratio, have been found to be significant prognostic factors in patients with breast cancer. However, the role of PVIs for predicting survival in breast cancer remains unknown; hence, we performed this retrospective analysis of 275 patients with breast cancer. PVIs were compared with clinicopathological variables, and were assessed to identify independent indicators associated with disease-free survival (DFS) using the Cox proportional hazards model. An elevated PDW/P significantly correlated with age and HER2 status. Univariate analysis revealed that elevated PDW, MPV, and PDW/P as well as tumor size, nuclear grade, and lymph node involvement were significantly associated with inferior DFS rates (tumor size: p<0.01; nuclear grade, lymph node involvement, PDW, MPV, and PDW/P: p<0.05). On multivariate analysis, a large tumor size and elevated PDW/P were significant prognostic factors for DFS, with hazard ratios of 3.24 (95% confidence interval [CI]: 1.24-8.47) and 2.99 (95% CI: 1.18-7.57), respectively (p<0.05). Our study is the first to reveal that an elevated PDW/P significantly reduces DFS in patients with breast carcinoma. Measuring the PDW/P is simple, relatively inexpensive, and almost universally available using routine blood counts; this makes it an attractive biomarker for improved risk assessment.

Platelet-inspired medicine for tumor therapy

As the number of patients with tumor increases dramatically recent years, traditional therapies expose more and more problems which can even lead to death. Many researchers and clinicians quest for an efficient drug delivery system to deal with tumor as a result. With the researches further develop, we find that platelet can interact with tumor cells through a variety of ways. So it can be used as a carrier broadly to deliver different anti-tumor drugs for tumor treatment. In the present review, we summarize the interaction of tumor cells and platelet. At the same time, we focus on recent progress on the application of platelet drug-loaded system in the anti-tumor prospects.

Enhancer of Zeste homolog 2 (EZH2) induces epithelial-mesenchymal transition in endometriosis

EZH2, a subunit of the polycomb repressive complex 2 (PRC2) catalyzing trimethylation of histone H3 lysine 27 (H3K27), induces epithelial-mesenchymal transition (EMT) in cancers. However, whether EZH2 regulates EMT in endometriosis is unclear. Here, we show that EZH2 expression, along with its associated PRC2 proteins, is significantly elevated in ectopic and eutopic endometrium from women with endometriosis as compared with control endometrium. EZH2 knockdown or inhibition restored the epithelial phenotypes of endometriotic epithelial cells, concomitant with the upregulation of E-cadherin and downregulation of vimentin and transcription factors (Snail and Slug) as well as reduced cellular migratory and invasive propensity. Conversely, overexpression of EZH2 induced the expression of Snail, Slug and vimentin and suppresses E-cadherin expression. In vivo administration of 3-Deazaneplanocin A (DZNep), an EZH2 inhibitor, significantly inhibited the growth of endometriotic lesions and improved generalized hyperalgesia, along with attenuated EMT and reduced fibrosis in endometriosis. Notably, platelets induced EZH2 upregulation and increased H3K27 and H3K9 trimethylation levels in endometriotic epithelial cells. These data identify EZH2 as a novel driver of EMT in endometriosis, implicates the link between wound healing and epigenetic changes in the context of endometriosis, and underscore the role of platelets in the development of endometriosis.

Immuno-Oncology Integrative Networks: Elucidating the Influences of Osteosarcoma Phenotypes

In vivo and in vitro functional phenotyping characterization was recently obtained with reference to an experimental pan-cancer study of 22 osteosarcoma (OS) cell lines. Here, differentially expressed gene (DEG) profiles were recomputed from the publicly available data to conduct network inference on the immune system regulatory activity across the characterized OS phenotypes. Based on such DEG profiles, and for each phenotype that was analyzed, we obtained coexpression networks and bio-annotations for them. Then, we described the immune-modulated influences in phenotype-specific networks' integrating pathway, transcription factor, and microRNA regulations. Overall, this approach seems suitable for representing heterogeneity in OS tumorigenesis.

Integrin β3/Akt signaling contributes to platelet-induced hemangioendothelioma growth

Hemangioendothelioma (HE) is a type of angiomatous lesions that features endothelial cell proliferation. Understanding the mechanisms orchestrating HE angiogenesis can provide therapeutic insights. It has been shown that platelets can support normal and malignant endothelial cells during angiogenesis. Using the mouse endothelial-derived EOMA cell line as a model of HE, we explored the regulatory effect of platelets. We found that platelets stimulated EOMA proliferation but did not mitigate apoptosis. Furthermore, direct platelet-EOMA cell contact was required and the proliferation was mediated via integrin β3/Akt signaling in EOMA cells. SiRNA knockdown of integrin β3 and inhibition of Akt activity significantly abolished platelet-induced EOMA cell proliferation in vitro and tumor development in vivo. These results provide a new mechanism by which platelets support HE progression and suggest integrin β3 as a potential target to treat HE.

Podoplanin enhances lung cancer cell growth in vivo by inducing platelet aggregation

Podoplanin/Aggrus, known as a platelet aggregation-inducing factor, is frequently overexpressed in lung squamous cell carcinomas (LSCC) and glioblastomas among other tumours, and its expression has been reported to be correlated with poor prognosis. However, the contribution of podoplanin to malignant progression has been elusive. Here we demonstrate that in podoplanin-positive LSCC cells, their growth was abrogated by podoplanin knockout in vivo but not in vitro. Conversely, ectopic expression of podoplanin promoted cell growth in vivo and facilitated intratumoral platelet activation. Consistently, LSCC cells evoked podoplanin-mediated platelet aggregation (PMPA), and the releasates from platelets during PMPA promoted the growth of LSCC cells in vitro. Phospho-receptor-tyrosine-kinase array analysis revealed that epidermal growth factor receptor (EGFR) phosphorylation of LSCC cells was responsible for the growth promotion induced by platelet releasates. Treatment with an antiplatelet agent or podoplanin-neutralizing antibody depressed the growth of an LSCC tumour xenograft via suppression of EGFR phosphorylation. These results suggested that podoplanin in LSCC enhanced cell growth by inducing PMPA in vivo and contributed to malignant progression.

Platelet releasates promote the proliferation of hepatocellular carcinoma cells by suppressing the expression of KLF6

Platelets in the primary tumor microenvironment play crucial roles in the regulation of tumor progression, but the mechanisms underlying are poorly understood. Here, we report that platelet releasates exerted a proliferative effect on hepatocellular carcinoma (HCC) cells both in vitro and in vivo. This effect depended on a reduction of KLF6 expression in HCC cells. After incubation with either platelets or platelet granule contents, SMMC.7721 and HepG2 cells exhibited significant increases in proliferation and decreases in apoptosis. However, no effect was observed when incubating cancer cells with resuspended activated platelet pellet which exhausted of releasates. Platelet releasates also increased the population of HCC cells in the S and G2/M phases of the cell cycle and reduced the cell population in the G0/G1 phase. Moreover, knocking down KLF6 expression significantly diminished the platelet-mediated enhancement of HCC growth. In addition, blocking TGF-β signaling with the TGF-β receptor inhibitor SB431542 counteracted the effect of platelets on KLF6 expression and proliferation of HCC cells. Based on these findings, we conclude that platelet releasates, especially TGF-β, promote the proliferation of SMMC.7721 and HepG2 cells by decreasing expression of KLF6. This discovery identifies a potential new therapeutic target for the prevention and treatment of hepatocellular carcinoma.

Lack of association between platelet indices and disease stage in osteosarcoma at diagnosis

Purpose

The purpose of this study was to investigate the relationship between platelet indices [mean platelet volume (MPV), platelet count (PLT), platelet distribution width (PDW) and plateletcrit (PCT)] at diagnosis in osteosarcoma.

Methods

The information of 233 patients with osteosarcoma at diagnosis between 2007 and 2015 was retrospectively reviewed. Clinical parameters such as gender, age, size and site of tumor, and tumor necrosis rate after neoadjuvant chemotherapy were analyzed.

Results

No significant difference was noted in the mean values of MPV, PLT, PDW and PCT among stage I, II and III patients. In localized patients, the median disease-free survival (DFS) values were 42 and 22 months in the PLT<300×10⁹/L and ≥300×10⁹/L groups, respectively, but the difference was not statistically significant (P = 0.2611). No difference in the DFS among the three different levels of MPV was observed.

Conclusion

No significantly different platelet indices were noted among the different stages. Although a shorter median DFS was found in localized patients with PLT≥300×10⁹/L, there was still a lack of strong evidence to demonstrate the association between platelet indices and osteosarcoma.

A critical role of platelet TGF-β release in podoplanin-mediated tumour invasion and metastasis

The tumour microenvironment is critical for various characteristics of tumour malignancies. Platelets, as part of the tumour microenvironment, are associated with metastasis formation via increasing the rate of tumour embolus formation in microvasculature. However, the mechanisms underlying the ability of tumour cells to acquire invasiveness and extravasate into target organs at the site of embolization remain unclear. In this study, we reported that platelet aggregation-inducing factor podoplanin expressed on tumour cell surfaces were found to not only promote the formation of tumour-platelet aggregates via interaction with platelets, but also induced the epithelial-mesenchymal transition (EMT) of tumour cells by enhancing transforming growth factor-β (TGF-β) release from platelets. In vitro and in vivo analyses revealed that podoplanin-mediated EMT resulted in increased invasiveness and extravasation of tumour cells. Treatment of mice with a TGF-β-neutralizing antibody statistically suppressed podoplanin-mediated distant metastasis in vivo, suggesting that podoplanin promoted haematogenous metastasis in part by releasing TGF-β from platelets that was essential for EMT of tumour cells. Therefore, our findings suggested that blocking the TGF-β signalling pathway might be a promising strategy for suppressing podoplanin-mediated haematogenous metastasis in vivo.

Osteosarcoma Overview

Osteosarcoma (OS) is the most common primary malignancy of bone and patients with metastatic disease or recurrences continue to have very poor outcomes. Unfortunately, little prognostic improvement has been generated from the last 20 years of research and a new perspective is warranted. OS is extremely heterogeneous in both its origins and manifestations. Although multiple associations have been made between the development of osteosarcoma and race, gender, age, various genomic alterations, and exposure situations among others, the etiology remains unclear and controversial. Noninvasive diagnostic methods include serum markers like alkaline phosphatase and a growing variety of imaging techniques including X-ray, computed tomography, magnetic resonance imaging, and positron emission as well as combinations thereof. Still, biopsy and microscopic examination are required to confirm the diagnosis and carry additional prognostic implications such as subtype classification and histological response to neoadjuvant chemotherapy. The current standard of care combines surgical and chemotherapeutic techniques, with a multitude of experimental biologics and small molecules currently in development and some in clinical trial phases. In this review, in addition to summarizing the current understanding of OS etiology, diagnostic methods, and the current standard of care, our group describes various experimental therapeutics and provides evidence to encourage a potential paradigm shift toward the introduction of immunomodulation, which may offer a more comprehensive approach to battling cancer pleomorphism.