Molecular mechanisms of platelet activation and aggregation induced by breast cancer cells

Identification of Podoplanin Aptamers by SELEX for Protein Detection and Inhibition of Platelet Aggregation Stimulated by C-Type Lectin-like Receptor 2

Tumor cell-induced platelet aggregation (TCIPA) is a mechanism for the protection of tumor cells in the bloodstream and the promotion of tumor progression and metastases. The platelet C-type lectin-like receptor 2 (CLEC-2) can bind podoplanin (PDPN) on a cancer cell surface to facilitate TCIPA. Selective blockage of PDPN-mediated platelet-tumor cell interaction is a plausible strategy for inhibiting metastases. In this study, we aimed to screen for aptamers, which are the single-stranded DNA oligonucleotides that form a specific three-dimensional structure, bind to specific molecular targets with high affinity and specificity, bind to PDPN, and interfere with PDPN/CLEC-2 interactions. The systematic evolution of ligands by exponential enrichment (SELEX) was employed to enrich aptamers that recognize PDPN. The initial characterization of ssDNA pools enriched by SELEX revealed a PDPN aptamer designated as A1 displaying parallel-type G-quadruplexes and long stem-and-loop structures and binding PDPN with a material with a dissociation constant (Kd) of 1.3 ± 1.2 nM. The A1 aptamer recognized both the native and denatured form of PDPN. Notably, the A1 aptamer was able to quantitatively detect PDPN proteins in Western blot analysis. The A1 aptamer could interfere with the interaction between PDPN and CLEC-2 and inhibit PDPN-induced platelet aggregation in a concentration-dependent manner. These findings indicated that the A1 aptamer is a candidate for the development of biosensors in detecting the levels of PDPN expression. The action by A1 aptamer could result in the prevention of tumor cell metastases, and if so, could become an effective pharmacological agent in treating cancer patients.

Cancer progression and tumor hypercoagulability: a platelet perspective

Venous thromboembolism, which is common in cancer patients and accompanies or even precedes malignant tumors, is known as cancer-related thrombosis and is an important cause of cancer- associated death. At present, the exact etiology of the elevated incidence of venous thrombosis in cancer patients remains elusive. Platelets play a crucial role in blood coagulation, which is intimately linked to the development of arterial thrombosis. Additionally, platelets contribute to tumor progression and facilitate immune evasion by tumors. Tumor cells can interact with the coagulation system through various mechanisms, such as producing hemostatic proteins, activating platelets, and directly adhering to normal cells. The relationship between platelets and malignant tumors is also significant. In this review article, we will explore these connections.

Platelet-derived microvesicles isolated from type-2 diabetes mellitus patients harbour an altered miRNA signature and drive MDA-MB-231 triple-negative breast cancer cell invasion

The underlying causes of breast cancer are diverse, however, there is a striking association between type 2 diabetes and poor patient outcomes. Platelet activation is a common feature of both type 2 diabetes and breast cancer and has been implicated in tumourigenesis through a multitude of pathways. Here transcriptomic analysis of type 2 diabetes patient-derived platelet microvesicles revealed an altered miRNA signature compared with normoglycaemic control patients. Interestingly, interrogation of these data identifies a shift towards an oncogenic signature in type 2 diabetes-derived platelet microvesicles, with increased levels of miRNAs implicated in breast cancer progression and poor prognosis. Functional studies demonstrate that platelet microvesicles isolated from type 2 diabetes patient blood are internalised by triple-negative breast cancer cells in vitro, and that co-incubation with type 2 diabetes patient-derived platelet microvesicles led to significantly increased expression of epithelial to mesenchymal transition markers and triple-negative breast cancer cell invasion compared with platelet microvesicles from healthy volunteers. Together, these data suggest that circulating PMVs in type 2 diabetes patients may contribute to the progression of triple-negative breast cancer.

Cost-effective prognostic evaluation of breast cancer: using a STAR nomogram model based on routine blood tests

Background

Breast cancer (BC) is the most common and prominent deadly disease among women. Predicting BC survival mainly relies on TNM staging, molecular profiling and imaging, hampered by subjectivity and expenses. This study aimed to establish an economical and reliable model using the most common preoperative routine blood tests (RT) data for survival and surveillance strategy management.

Methods

We examined 2863 BC patients, dividing them into training and validation cohorts (7:3). We collected demographic features, pathomics characteristics and preoperative 24-item RT data. BC risk factors were identified through Cox regression, and a predictive nomogram was established. Its performance was assessed using C-index, area under curves (AUC), calibration curve and decision curve analysis. Kaplan-Meier curves stratified patients into different risk groups. We further compared the STAR model (utilizing HE and RT methodologies) with alternative nomograms grounded in molecular profiling (employing second-generation short-read sequencing methodologies) and imaging (utilizing PET-CT methodologies).

Results

The STAR nomogram, incorporating subtype, TNM stage, age and preoperative RT data (LYM, LYM%, EOSO%, RDW-SD, P-LCR), achieved a C-index of 0.828 in the training cohort and impressive AUCs (0.847, 0.823 and 0.780) for 3-, 5- and 7-year OS rates, outperforming other nomograms. The validation cohort showed similar impressive results. The nomogram calculates a patient's total score by assigning values to each risk factor, higher scores indicating a poor prognosis. STAR promises potential cost savings by enabling less intensive surveillance in around 90% of BC patients. Compared to nomograms based on molecular profiling and imaging, STAR presents a more cost-effective, with potential savings of approximately $700-800 per breast cancer patient.

Conclusion

Combining appropriate RT parameters, STAR nomogram could help in the detection of patient anemia, coagulation function, inflammation and immune status. Practical implementation of the STAR nomogram in a clinical setting is feasible, and its potential clinical impact lies in its ability to provide an early, economical and reliable tool for survival prediction and surveillance strategy management. However, our model still has limitations and requires external data validation. In subsequent studies, we plan to mitigate the potential impact on model robustness by further updating and adjusting the data and model.

Design, Synthesis, and Antitumor Evaluation of an Opioid Growth Factor Bioconjugate Targeting Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) presents a formidable challenge with high lethality and limited effective drug treatments. Its heightened metastatic potential further complicates the prognosis. Owing to the significant toxicity of current chemotherapeutics, compounds like [Met5]-enkephalin, known as opioid growth factor (OGF), have emerged in oncology clinical trials. OGF, an endogenous peptide interacting with the OGF receptor (OGFr), plays a crucial role in inhibiting cell proliferation across various cancer types. This in vitro study explores the potential anticancer efficacy of a newly synthesized OGF bioconjugate in synergy with the classic chemotherapeutic agent, gemcitabine (OGF-Gem). The study delves into assessing the impact of the OGF-Gem conjugate on cell proliferation inhibition, cell cycle regulation, the induction of cellular senescence, and apoptosis. Furthermore, the antimetastatic potential of the OGF-Gem conjugate was demonstrated through evaluations using blood platelets and AsPC-1 cells with a light aggregometer. In summary, this article demonstrates the cytotoxic impact of the innovative OGF-Gem conjugate on pancreatic cancer cells in both 2D and 3D models. We highlight the potential of both the OGF-Gem conjugate and OGF alone in effectively inhibiting the ex vivo pancreatic tumor cell-induced platelet aggregation (TCIPA) process, a phenomenon not observed with Gem alone. Furthermore, the confirmed hemocompatibility of OGF-Gem with platelets reinforces its promising potential. We anticipate that this conjugation strategy will open avenues for the development of potent anticancer agents.

The C-Type Lectin Receptor CD93 Regulates Platelet Activation and Surface Expression of the Protease Activated Receptor 4

BACKGROUND

 The C-type lectin receptor CD93 is a single pass type I transmembrane glycoprotein involved in inflammation, immunity, and angiogenesis. This study investigates the role of CD93 in platelet function. CD93 knockout (KO) mice and wild-type (WT) controls were compared in this study.

METHODS

 Platelet activation and aggregation were investigated by flow cytometry and light transmission aggregometry, respectively. Protein expression and phosphorylation were analyzed by immunoblotting. Subcellular localization of membrane receptors was investigated by wide-field and confocal microscopy.

RESULTS

 The lack of CD93 in mice was not associated to any evident bleeding defect and no alterations of platelet activation were observed upon stimulation with thromboxane A2 analogue and convulxin. Conversely, platelet aggregation induced by stimulation of the thrombin receptor PAR4 was significantly reduced in the absence of CD93. This defect was associated with a significant reduction of α-granule secretion, integrin αIIbβ3 activation, and protein kinase C (PKC) stimulation. Resting WT and CD93-deficient platelets expressed comparable amounts of PAR4. However, upon stimulation with a PAR4 activating peptide, a more pronounced clearance of PAR4 from the platelet surface was observed in CD93-deficient platelets compared with WT controls. Confocal microscopy analysis revealed a massive movement of PAR4 in cytosolic compartments of activated platelets lacking CD93. Accordingly, platelet desensitization following PAR4 stimulation was more pronounced in CD93 KO platelets compared with WT controls.

CONCLUSION

 These results demonstrate that CD93 supports platelet activation triggered by PAR4 stimulation and is required to stabilize the expression of the thrombin receptor on the cell surface.

A change of rhodocytin's suprastructure turns the agonist into an antagonist of tumor cell induced platelet aggregation

Cancer cells circulating in the blood attach to platelets by direct cell-cell interactions via several receptor-counterreceptor contacts and indirectly by fibrin bridges which connect the two cell types by distinct integrin receptors. In the microenvironment of these tumor cell platelet aggregates (TCPAs), the tumor cells are shielded from the shear stress of the blood flow and from attack by the immune system. This supports hematogenous metastasis and tumor cell induced thrombosis. Platelet activation is triggered by binding of podoplanin on cancer cells to the platelet receptor Clec-2. Therefore, we hypothesize that targeting this initial step will prevent the entire cascade leading to the formation of TCPAs. Rhodocytin, a heterodimeric (αβ)2 C-type lectin from the Malayan pit viper Calloselasma rhodostoma, binds to Clec-2 and thereby induces TCPA formation. Remarkably, mutations in rhodocytin that disturbed formation of oligomers, blocked the podoplanin-Clec-2 axis and prevented platelet activation. Therefore, we used lysine reactive chemicals to modify rhodocytin isolated from the crude snake venom. Blue native gel electrophoresis and far western blotting showed a change of rhodocytin's suprastructure triggered by acetylation and PEGylation. Mass spectrometry analysis of altered lysines suggested that their modifications interfered with the formation of rhodocytin tetramers. When tested in assays for tumor cell induced platelet aggregation, we found that derivatization turned rhodocytin from an agonist into an antagonist. This observation indicates that Clec-2 is a valid target receptor molecule to curb TCPA formation and to prevent hematogenous metastasis and tumor cell induced thrombosis in cancer patients.

Impact of platelet-derived mitochondria transfer in the metabolic profiling and progression of metastatic MDA-MB-231 human triple-negative breast cancer cells

Introduction: An active role of platelets in the progression of triple-negative breast cancer (TNBC) cells has been described. Even the role of platelet-derived extracellular vesicles on the migration of MDA-MB-231 cells has been reported. Interestingly, upon activation, platelets release functional mitochondria into the extracellular environment. However, the impact of these platelet-derived mitochondria on the metabolic properties of MDA-MB-231 cells remains unclear. Methods: MDA-MB-231 and MDA-MB-231-Rho-0 cells were co-cultured with platelets, which were isolated from donor blood. Mitochondrial transfer was assessed through confocal microscopy and flow cytometry, while metabolic analyses were conducted using a Seahorse XF HS Mini Analyzer. The mito-chondrial DNA (mtDNA) copy number was determined via quantitative PCR (qPCR) following platelet co-culture. Finally, cell proliferation and colony formation assay were performed using crystal violet staining. Results and Discussion: We have shown that platelet-derived mitochondria are internalized by MDA-MB-231 cells in co-culture with platelets, increasing ATP production, oxygen (O2) consumption rate (OCR), cell proliferation, and metabolic adaptability. Additionally, we observed that MDA-MB-231 cells depleted from mtDNA restore cell proliferation in uridine/pyruvate-free cell culture medium and mitochondrial O2 consumption after co-culture with platelets, indicating a reconstitution of mtDNA facilitated by platelet-derived mitochondria. In conclusion, our study provides new insights into the role of platelet-derived mitochondria in the metabolic adaptability and progression of metastatic MDA-MB-231 TNBC cells.

P2 purinergic receptors regulate the progression of colorectal cancer

More and more studies have revealed that P2 purinergic receptors play a key role in the progression of colorectal cancer (CRC). P2X and P2Y purinergic receptors can be used as promoters and regulators of CRC and play a dual role in the progression of CRC. CRC microenvironment is rich in ATP and its cleavage products (ADP, AMP, Ado), which act as activators of P2X and P2Y purinergic receptors. The activation of P2X and P2Y purinergic receptors regulates the progression of CRC mainly by regulating the function of immune cells and mediating different signal pathways. In this paper, we focus on the specific mechanisms and functional roles of P2X7, P2Y12, and P2Y2 receptors in the growth and progression of CRC. The antagonistic effects of these selective antagonists of P2X purinergic receptors on the growth, invasion, and metastasis of CRC were further discussed. Moreover, different studies have reported that P2X7 receptor can be used as an effective predictor of patients with CRC. All these indicate that P2 purinergic receptors are a key regulator of CRC. Therefore, antagonizing P2 purinergic receptors may be an innovative treatment for CRC.

Circulating tumor cells participate in the formation of microvascular invasion and impact on clinical outcomes in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a common malignant tumor worldwide. Although the treatment strategies have been improved in recent years, the long-term prognosis of HCC is far from satisfactory mainly due to high postoperative recurrence and metastasis rate. Vascular tumor thrombus, including microvascular invasion (MVI) and portal vein tumor thrombus (PVTT), affects the outcome of hepatectomy and liver transplantation. If vascular invasion could be found preoperatively, especially the risk of MVI, more reasonable surgical selection will be chosen to reduce the risk of postoperative recurrence and metastasis. However, there is a lack of reliable prediction methods, and the formation mechanism of MVI/PVTT is still unclear. At present, there is no study to explore the possibility of tumor thrombus formation from a single circulating tumor cell (CTC) of HCC, nor any related study to describe the possible leading role and molecular mechanism of HCC CTCs as an important component of MVI/PVTT. In this study, we review the current understanding of MVI and possible mechanisms, discuss the function of CTCs in the formation of MVI and interaction with immune cells in the circulation. In conclusion, we discuss implications for potential therapeutic targets and the prospect of clinical treatment of HCC.

Identification of a coagulation-related signature correlated with immune infiltration and their prognostic implications in lung adenocarcinoma

BACKGROUND

Lung adenocarcinoma (LUAD) is a fatal form of lung cancer with a poor prognosis. Coagulation system had been confirmed closely related to tumor progression and the hypercoagulable state encouraged the immune infiltration and development of tumor cells, leading to a poor prognosis in cancer patients. However, the use of the coagulation-related genes (CRGs) for prognosis in LUAD has yet to be determined. In this study, we constructed an immune-related signature (CRRS) and identified a potential coagulation-related biomarker (P2RX1).

METHODS

We obtained a total of 209 CRGs based on two coagulation-related KEGG pathways, then developed the CRRS signature by using the TCGA-LUAD RNA-seq data via the procedure of LASSO-Cox regression, stepwise-Cox regression, univariate and multivariate Cox regression. Grouped by the CRRS, Kaplan-Meier survival curves and receiver operating characteristic curves were drawn for the training and validation sets, respectively. In addition, single-sample gene set enrichment analysis was exploited to explore immune infiltration level. Moreover, immunophenotypes and immunotherapy grouped by CRRS were further analyzed.

RESULTS

We developed an immune-related signature (CRRS) composed of COL1A2, F2, PLAUR, C4BPA, and P2RX1 in LUAD. CRRS was an independent risk factor for overall survival and displayed stable and powerful performance. Additionally, CRRS possessed distinctly superior accuracy than traditional clinical variables and molecular features. Functional analysis indicated that the differentially high expressed genes in the low-risk group significantly enriched in T cell and B cell receptor signaling pathways. The low-risk group was sensitive to anti-PD-1/PD-L1 immunotherapy and displayed abundant immune infiltration and immune checkpoint gene expression. Finally, we identified an independent prognostic gene P2RX1. Low expression of P2RX1 associated with poor overall survival and decreased immune infiltration.

CONCLUSIONS

Our study revealed a significant correlation between CRRS and immune infiltration. CRRS could serve as a promising tool to improve the clinical outcomes for individual LUAD patients.

Reprogramming the immunosuppressive tumor microenvironment: exploiting angiogenesis and thrombosis to enhance immunotherapy

This review focuses on the immunosuppressive effects of tumor angiogenesis and coagulation on the tumor microenvironment (TME). We summarize previous research efforts leveraging these observations and targeting these processes to enhance immunotherapy outcomes. Clinical trials have documented improved outcomes when combining anti-angiogenic agents and immunotherapy. However, their overall survival benefit over conventional therapy remains limited and certain tumors exhibit poor response to anti-angiogenic therapy. Additionally, whilst preclinical studies have shown several components of the tumor coagulome to curb effective anti-tumor immune responses, the clinical studies reporting combinations of anticoagulants with immunotherapies have demonstrated variable treatment outcomes. By reviewing the current state of the literature on this topic, we address the key questions and future directions in the field, the answers of which are crucial for developing effective strategies to reprogram the TME in order to further the field of cancer immunotherapy.

Tumor educated platelet: the novel BioSource for cancer detection

Platelets, involved in the whole process of tumorigenesis and development, constantly absorb and enrich tumor-specific substances in the circulation during their life span, thus called "Tumor Educated Platelets" (TEPs). The alterations of platelet mRNA profiles have been identified as tumor markers due to the regulatory mechanism of post-transcriptional splicing. Small nuclear RNAs (SnRNAs), the important spliceosome components in platelets, dominate platelet RNA splicing and regulate the splicing intensity of pre-mRNA. Endogenous variation at the snRNA levels leads to widespread differences in alternative splicing, thereby driving the development and progression of neoplastic diseases. This review systematically expounds the bidirectional tumor-platelets interactions, especially the tumor induced alternative splicing in TEP, and further explores whether molecules related to alternative splicing such as snRNAs can serve as novel biomarkers for cancer diagnostics.

G protein-coupled P2Y12 receptor is involved in the progression of neuropathic pain

The pathological mechanism of neuropathic pain is complex, which seriously affects the physical and mental health of patients, and its treatment is also difficult. The role of G protein-coupled P2Y12 receptor in pain has been widely recognized and affirmed. After nerve injury, stimulated cells can release large amounts of nucleotides into the extracellular matrix, act on P2Y12 receptor. Activated P2Y12 receptor activates intracellular signal transduction and is involved in the development of pain. P2Y12 receptor activation can sensitize primary sensory neurons and receive sensory information. By transmitting the integrated information through the dorsal root of the spinal cord to the secondary neurons of the posterior horn of the spinal cord. The integrated information is then transmitted to the higher center through the ascending conduction tract to produce pain. Moreover, activation of P2Y12 receptor can mediate immune cells to release pro-inflammatory factors, increase damage to nerve cells, and aggravate pain. While inhibits the activation of P2Y12 receptor can effectively relieve pain. Therefore, in this article, we described P2Y12 receptor antagonists and their pharmacological properties. In addition, we explored the potential link between P2Y12 receptor and the nervous system, discussed the intrinsic link of P2Y12 receptor and neuropathic pain and as a potential pharmacological target for pain suppression.

Stimulation of platelet aggregation by affinity captured rhodocytin from the Malayan pit viper Calloselasma rhodostoma

The receptor protein CLEC-2 on platelet membranes is the target of the endogenous ligand podoplanin found on cancer cells and of rhodocytin, a snake venom component of the Malayan pit viper Calloselasma rhodostoma. Ligand binding results in platelet activation, increased blood coagulation and thrombosis. In an effort to isolate rhodocytin, we have purified CLEC-2 as bait from E. coli. Affinity captured rhodocytin interacted with mammalian CLEC-2 and stimulated platelet aggregation in a dose dependent manner.

Prostate cancer cell-platelet bidirectional signaling promotes calcium mobilization, invasion and apoptotic resistance via distinct receptor-ligand pairs

Platelets play a crucial role in cancer and thrombosis. However, the receptor-ligand repertoire mediating prostate cancer (PCa) cell-platelet interactions and ensuing consequences have not been fully elucidated. Microvilli emanating from the plasma membrane of PCa cell lines (RC77 T/E, MDA PCa 2b) directly contacted individual platelets and platelet aggregates. PCa cell-platelet interactions were associated with calcium mobilization in platelets, and translocation of P-selectin and integrin α_IIbβ₃ onto the platelet surface. PCa cell-platelet interactions reciprocally promoted PCa cell invasion and apoptotic resistance, and these events were insensitive to androgen receptor blockade by bicalutamide. PCa cells were exceedingly sensitive to activation by platelets in vitro, occurring at a PCa cell:platelet coculture ratio as low as 1:10 (whereas PCa patient blood contains 1:2,000,000 per ml). Conditioned medium from cocultures stimulated PCa cell invasion but not apoptotic resistance nor platelet aggregation. Candidate transmembrane signaling proteins responsible for PCa cell-platelet oncogenic events were identified by RNA-Seq and broadly divided into 4 major categories: (1) integrin-ligand, (2) EPH receptor-ephrin, (3) immune checkpoint receptor-ligand, and (4) miscellaneous receptor-ligand interactions. Based on antibody neutralization and small molecule inhibitor assays, PCa cell-stimulated calcium mobilization in platelets was found to be mediated by a fibronectin1 (FN1)-α_IIbβ₃ signaling axis. Platelet-stimulated PCa cell invasion was facilitated by a CD55-adhesion G protein coupled receptor E5 (ADGRE5) axis, with contribution from platelet cytokines CCL3L1 and IL32. Platelet-stimulated PCa cell apoptotic resistance relied on ephrin-EPH receptor and lysophosphatidic acid (LPA)-LPA receptor (LPAR) signaling. Of participating signaling partners, FN1 and LPAR3 overexpression was observed in PCa specimens compared to normal prostate, while high expression of CCR1 (CCL3L1 receptor), EPHA1 and LPAR5 in PCa was associated with poor patient survival. These findings emphasize that non-overlapping receptor-ligand pairs participate in oncogenesis and thrombosis, highlighting the complexity of any contemplated clinical intervention strategy.

Contents in tumor-educated platelets as the novel biosource for cancer diagnostics

Liquid biopsy, a powerful non-invasive test, has been widely used in cancer diagnosis and treatment. Platelets, the second most abundant cells in peripheral blood, are becoming one of the richest sources of liquid biopsy with the capacity to systematically and locally respond to the presence of cancer and absorb and store circulating proteins and different types of nucleic acids, thus called "tumor-educated platelets (TEPs)". The contents of TEPs are significantly and specifically altered, empowering them with the potential as cancer biomarkers. The current review focuses on the alternation of TEP content, including coding and non-coding RNA and proteins, and their role in cancer diagnostics.

Targeting Platelet Activation Pathways to Limit Tumour Progression: Current State of Affairs

The association between cancer and a hypercoagulatory environment is well described. Thrombotic complications serve not only as a major mortality risk but the underlying molecular structure and function play significant roles in enhancing tumour progression, which is defined as the tumour's capacity to survive, invade and metastasise, amongst other hallmarks of the disease. The use of anticoagulant or antiplatelet drugs in cardiovascular disease lessens thrombotic effects, but the consequences on tumour progression require interrogation. Therefore, this review considered developments in the management of platelet activation pathways (thromboxane, ADP and thrombin), focusing on the use of Aspirin, Clopidogrel and Atopaxar, and their potential impacts on tumour progression. Published data suggested a cautionary tale in ensuring we adequately investigate not only drug-drug interactions but also those unforeseen reciprocal interactions between drugs and their targets within the tumour microenvironment that may act as selective pressures, enhancing tumour survival and progression.

Proteomic and functional profiling of platelet-derived extracellular vesicles released under physiological or tumor-associated conditions

During hemostasis, thrombosis, and inflammation, activated blood platelets release extracellular vesicles (PEVs) that represent biological mediators of physiological and pathological processes. We have recently demonstrated that the activation of platelets by breast cancer cells is accompanied by a massive release of PEVs, evidence that matches with the observation that breast cancer patients display increased levels of circulating PEVs. A core concept in PEVs biology is that their nature, composition and biological function are strongly influenced by the conditions that induced their release. In this study we have performed a comparative characterization of PEVs released by platelets upon activation with thrombin, a potent thrombotic stimulus, and upon exposure to the breast cancer cell line MDA-MB-231. By nanoparticle tracking analysis and tandem mass spectrometry we have characterized the two populations of PEVs, showing that the thrombotic and tumoral stimuli produced vesicles that largely differ in protein composition. The bioinformatic analysis of the proteomic data led to the identification of signaling pathways that can be differently affected by the two PEVs population in target cells. Specifically, we have demonstrated that both thrombin- and cancer-cell-induced PEVs reduce the migration and potentiate Ca2+-induced apoptosis of Jurkat cells, but only thrombin-derived PEVs also potentiate cell necrosis. Our results demonstrate that stimulation of platelets by thrombotic or tumoral stimuli induces the release of PEVs with different protein composition that, in turn, may elicit selective biological responses in target cells.

Pharmacological Actions of 5-Hydroxyindolin-2 on Modulation of Platelet Functions and Thrombus Formation via Thromboxane A2 Inhibition and cAMP Production

Platelets play a very significant role in hemostasis while simultaneously posing a risk for the development of various cardiovascular diseases. Platelet-mediated issues can occur in blood vessels and trigger various medical problems. Therefore, controlling platelet function is important in the prevention of thrombosis. In this regard, we need to find compounds that provide potent antiplatelet activity with minimum side effects. Therefore, we examined the effect of 5-hydroxyindolin-2-one isolated from Protaetia brevitarsis larvae having antiplatelet properties and investigated different pathways that mediate the antiplatelet activity. We examined the effect of 5-hydroxyindolin-2-one (5-HI) on the regulation of phosphoproteins, thromboxane A₂ generation, and integrin αIIbβ3 action. Our data showed that human platelet aggregation was inhibited by 5-HI (75, 100, 150, 200 μM) without cytotoxicity, and it suppressed intracellular Ca²⁺ concentration through the regulation of inositol 1, 4, 5-triphosphate receptor I (Ser¹⁷⁵⁶) and extracellular signal-regulated kinase (ERK). Moreover, collagen-elevated thromboxane A₂ production and αIIbβ3 action were inhibited by 5-HI through the regulation of cytosolic phospholipase A₂ (cPLA₂), mitogen-activated protein kinase p38 (p38^MAPK), vasodilator-stimulated phosphoprotein (VASP), phosphoinositide 3-kinase (PI3K), and Akt (protein kinase B). Therefore, we suggested that 5-HI could be a potential substance for the prevention of thrombosis-mediated thrombosis.

Pivotal role of PD-1/PD-L1 immune checkpoints in immune escape and cancer progression: Their interplay with platelets and FOXP3+Tregs related molecules, clinical implications and combinational potential with phytochemicals

Immune checkpoint proteins including programmed cell death protein 1 (PD-1), its ligand PD-L1 and cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) are involved in proliferation, angiogenesis, metastasis, chemoresistance via immune escape and immune tolerance by disturbing cytotoxic T cell activation. Though many clinical trials have been completed in several cancers by using immune checkpoint inhibitors alone or in combination with other agents to date, recently multi-target therapy is considered more attractive than monotherapy, since immune checkpoint proteins work with other components such as surrounding blood vessels, dendritic cells, fibroblasts, macrophages, platelets and extracellular matrix within tumor microenvironment. Thus, in the current review, we look back on research history of immune checkpoint proteins and discuss their associations with platelets or tumor cell induced platelet aggregation (TCIPA) and FOXP3+ regulatory T cells (Tregs) related molecules involved in immune evasion and tumor progression, clinical implications of completed trial results and signaling networks by phytochemicals for combination therapy with immune checkpoint inhibitors and suggest future research perspectives.

Characterization of coagulation-related gene signature to predict prognosis and tumor immune microenvironment in skin cutaneous melanoma

Backgroud

Skin cutaneous melanoma (SKCM) is an extremely metastatic form of skin cancer. However, there are few valuable molecular biomarkers, and accurate diagnosis is still a challenge. Hypercoagulable state encourages the infiltration and development of tumor cells and is significantly associated with poor prognosis in cancer patients. However, the use of a coagulation-related gene (CRG) signature for prognosis in SKCM, on the other hand, has yet to be determined.

Method

We used data from The Cancer Genome Atlas (TCGA) and Genotype Tissue Expression (GTEx) databases to identify differentially expressed CRGs, then designed a prognostic model by using the LASSO algorithm, univariate and multivariate Cox regression analysis, and constructed a nomogram which was evaluated by calibration curves. Moreover, the Gene Expression Omnibus (GEO), GSE54467 was used as an independent validation. The correlation between risk score and clinicopathological characteristics, tumor microenvironment (TME), and immunotherapy was further analyzed.

Results

To develop a prognostic model, seven CRGs in SKCM patients related to overall survival (OS) were selected: ANG, C1QA, CFB, DUSP6, KLKB1, MMP7, and RABIF. According to the Kaplan-Meier survival analysis, an increased OS was observed in the low-risk group than in the high-risk group (P<0.05). Immunotherapy was much more beneficial in the low-risk group, as per immune infiltration, functional enrichment, and immunotherapy analysis.

Conclusions

The prognosis of SKCM patients may now be predicted with the use of a CRG prognostic model, thus guiding the development of treatment plans for SKCM patients and promoting OS rates.

Modelling the procoagulatory effect of Anastrozole relative to ERα and ERβ expression in breast cancer cells

BACKGROUND

Anastrozole is commonly used for the treatment of oestrogen receptor (ER)-positive breast cancer but can increase thromboembolic risk. It is unclear if ER presentation is associated with platelet-mediated hypercoagulation. We investigated the relationship between hypercoagulation and ERα and ERβ expression in breast cancer cell lines under Anastrozole treatment.

METHODS

In Model 1, MCF-7 or T47D cancer cells were treated with Anastrozole, then exposed to whole blood and platelet-rich plasma, modelling platelet engagement in the tumour bed. In Model 2, blood components were treated with Anastrozole, then exposed to cancer cells, modelling circulatory effects in the vasculature. Hypercoagulation was assessed as a combined function of thrombin activity, platelet CD62P and CD63 expression, and corresponding platelet ultrastructure. Tumour ERα and ERβ were immunolocalised and following quantification assessed for correlation with hypercoagulatory parameters.

RESULTS

Anastrozole enhanced hypercoagulation in both Models and cell lines. T47D cells induced more distinct features of hypercoagulation and responded by heightening ERβ expression and sustaining expression of ERα, indicative of a more aggressive phenotype. Post-exposure to cell lines, CD62P and CD63 expression correlated, but this was not maintained following Anastrozole treatment. Substantive correlations could not be found explaining the changes in ER expression and hypercoagulatory parameters, indicating unknown causative factors.

CONCLUSION

These results provide basic science evidence showing that the hypercoagulatory effects induced by Anastrozole treatment may be related to the tumour subphenotype. Clinical studies are required to determine whether tracking of hypercoagulatory parameters may hold value in describing subphenotypic alterations or metastatic potential during tumour progression.

Emerging roles of platelets in cancer biology and their potential as therapeutic targets

The main role of platelets is to control bleeding and repair vascular damage via thrombosis. They have also been implicated to promote tumor metastasis through platelet-tumor cell interactions. Platelet-tumor cell interactions promote tumor cell survival and dissemination in blood circulation. Tumor cells are known to induce platelet activation and alter platelet RNA profiles. Liquid biopsies based on tumor-educated platelet biomarkers can detect tumors and correlate with prognosis, personalized therapy, treatment monitoring, and recurrence prediction. Platelet-based strategies for cancer prevention and tumor-targeted therapy include developing drugs that target platelet receptors, interfere with the release of platelet particles, inhibit platelet-specific enzymes, and utilize platelet-derived “nano-platelets” as a targeted drug delivery platform for tumor therapy. This review elaborates on platelet-tumor cell interactions and the molecular mechanisms and discusses future research directions for platelet-based liquid biopsy techniques and platelet-targeted anti-tumor strategies.

Investigation of Biomarkers Associated with Low Platelet Counts in Normal Karyotype Acute Myeloid Leukemia

Acute myeloid leukemia (AML) patients are at risk of bleeding due to disease-related lack of platelets and systemic coagulopathy. Platelets play a role in hemostasis. Leukemic blasts have been shown to alter platelet activation in vitro. Here we investigated biomarkers associated with thrombocytopenia in normal karyotype AML (NK-AML). From The Cancer Genome Atlas database, case-control study was performed between normal karyotype (NK) platelet-decreased AML (PD-AML, platelet count < 100 × 109/L, n = 24) and NK platelet-not-decreased AML (PND-AML, with platelet count ≥ 100 × 109/L, n = 13). Differentially expressed gene analysis, pathway analysis and modelling for predicting platelet decrease in AML were performed. DEG analysis and pathway analysis revealed 157 genes and eight pathways specific for PD-AML, respectively. Most of the eight pathways were significantly involved in G-protein-coupled receptor-related pathway, cytokine-related pathway, and bone remodeling pathway. Among the key genes involved in at least one pathway, three genes including CSF1R, TNFSF15 and CLEC10A were selected as promising biomarkers for predicting PD-AML (0.847 of AUC in support vector machine model). This is the first study that identified biomarkers using RNA expression data analysis and could help understand the pathophysiology in AML with low platelet count.

Tumor Cell-Induced Platelet Aggregation as an Emerging Therapeutic Target for Cancer Therapy

Tumor cells have the ability to induce platelet activation and aggregation. This has been documented to be involved in tumor progression in several types of cancers, such as lung, colon, breast, pancreatic, ovarian, and brain. During the process, platelets protect circulating tumor cells from the deleterious effects of shear forces, shield tumor cells from the immune system, and provide growth factors, facilitating metastatic spread and tumor growth at the original site as well as at the site of metastasis. Herein, we present a wider view on the induction of platelet aggregation by specific factors primarily developed by cancer, including coagulation factors, adhesion receptors, growth factors, cysteine proteases, matrix metalloproteinases, glycoproteins, soluble mediators, and selectins. These factors may be presented on the surface of tumor cells as well as in their microenvironment, and some may trigger more than just one simple receptor-ligand mechanism. For a better understanding, we briefly discuss the physiological role of the factors in the platelet activation process, and subsequently, we provide scientific evidence and discuss their potential role in the progression of specific cancers. Targeting tumor cell-induced platelet aggregation (TCIPA) by antiplatelet drugs may open ways to develop new treatment modalities. On the one hand, it may affect patients' prognosis by enhancing known therapies in advanced-stage tumors. On the other hand, the use of drugs that are mostly easily accessible and widely used in general practice may be an opportunity to propose an unparalleled antitumor prophylaxis. In this review, we present the recent discoveries of mechanisms by which cancer cells activate platelets, and discuss new platelet-targeted therapeutic strategies.

Antiplatelet Agents Affecting GPCR Signaling Implicated in Tumor Metastasis

Metastasis requires that cancer cells survive in the circulation, colonize distant organs, and grow. Despite platelets being central contributors to hemostasis, leukocyte trafficking during inflammation, and vessel stability maintenance, there is significant evidence to support their essential role in supporting metastasis through different mechanisms. In addition to their direct interaction with cancer cells, thus forming heteroaggregates such as leukocytes, platelets release molecules that are necessary to promote a disseminating phenotype in cancer cells via the induction of an epithelial-mesenchymal-like transition. Therefore, agents that affect platelet activation can potentially restrain these prometastatic mechanisms. Although the primary adhesion of platelets to cancer cells is mainly independent of G protein-mediated signaling, soluble mediators released from platelets, such as ADP, thromboxane (TX) A2, and prostaglandin (PG) E2, act through G protein-coupled receptors (GPCRs) to cause the activation of more additional platelets and drive metastatic signaling pathways in cancer cells. In this review, we examine the contribution of the GPCRs of platelets and cancer cells in the development of cancer metastasis. Finally, the possible use of agents affecting GPCR signaling pathways as antimetastatic agents is discussed.

Platelet Membrane: An Outstanding Factor in Cancer Metastasis

In addition to being biological barriers where the internalization or release of biomolecules is decided, cell membranes are contact structures between the interior and exterior of the cell. Here, the processes of cell signaling mediated by receptors, ions, hormones, cytokines, enzymes, growth factors, extracellular matrix (ECM), and vesicles begin. They triggering several responses from the cell membrane that include rearranging its components according to the immediate needs of the cell, for example, in the membrane of platelets, the formation of filopodia and lamellipodia as a tissue repair response. In cancer, the cancer cells must adapt to the new tumor microenvironment (TME) and acquire capacities in the cell membrane to transform their shape, such as in the case of epithelial−mesenchymal transition (EMT) in the metastatic process. The cancer cells must also attract allies in this challenging process, such as platelets, fibroblasts associated with cancer (CAF), stromal cells, adipocytes, and the extracellular matrix itself, which limits tumor growth. The platelets are enucleated cells with fairly interesting growth factors, proangiogenic factors, cytokines, mRNA, and proteins, which support the development of a tumor microenvironment and support the metastatic process. This review will discuss the different actions that platelet membranes and cancer cell membranes carry out during their relationship in the tumor microenvironment and metastasis.

Improving hemocompatibility of decellularized liver scaffold using Custodiol solution

Organ decellularization is one of the most promising approaches of tissue engineering to overcome the shortage of organs available for transplantation. However, there are key hurdles that still hinder its clinical application, and the lack of hemocompatibility of decellularized materials is a central one. In this work, we demonstrate that Custodiol (HTK solution), a common solution used in organ transplantation, increased the hemocompatibility of acellular scaffolds obtained from rat livers. We showed that Custodiol inhibited ex vivo, in vitro, and in vivo blood coagulation to such extent that allowed successful transplantation of whole-liver scaffolds into recipient animals. Scaffolds previously perfused with Custodiol showed no signs of platelet aggregation and maintained in vitro and in vivo cellular compatibility. Proteomic analysis revealed that proteins related to platelet aggregation were reduced in Custodiol samples while control samples were enriched with thrombogenicity-related proteins. We also identified distinct components that could potentially be involved with this anti-thrombogenic effect and thus require further investigation. Therefore, Custodiol perfusion emerge as a promising strategy to reduce the thrombogenicity of decellularized biomaterials and could benefit several applications of whole-organ tissue engineering.

Glioma stem cells activate platelets by plasma-independent thrombin production to promote glioblastoma tumorigenesis

Background

The interaction between platelets and cancer cells has been underexplored in solid tumor models that do not metastasize, for example, glioblastoma (GBM) where metastasis is rare. Histologically, it is known that glioma stem cells (GSCs) are found in perivascular and pseudsopalisading regions of GBM, which are also areas of platelet localization. High platelet counts have been associated with poor clinical outcomes in many cancers. While platelets are known to promote the progression of other tumors, mechanisms by which platelets influence GBM oncogenesis are unknown. Here, we aimed to understand how the bidirectional interaction between platelets and GSCs drives GBM oncogenesis.

Methods

Male and female NSG mice were transplanted with GSC lines and treated with antiplatelet and anti-thrombin inhibitors. Immunofluorescence, qPCR, and Western blots were used to determine expression of coagulation mechanism in GBM tissue and subsequent GSC lines.

Results

We show that GSCs activate platelets by endogenous production of all the factors of the intrinsic and extrinsic coagulation cascades in a plasma-independent manner. Therefore, GSCs produce thrombin resulting in platelet activation. We further demonstrate that the endogenous coagulation cascades of these cancer stem cells are tumorigenic: they activate platelets to promote stemness and proliferation in vitro and pharmacological inhibition delays tumor growth in vivo.

Conclusions

Our findings uncover a specific preferential relationship between platelets and GSCs that drive GBM malignancies and identify a therapeutically targetable novel interaction.

Combination of Nanomaterials in Cell-Based Drug Delivery Systems for Cancer Treatment

Cell-based drug delivery systems have shown tremendous advantages in cancer treatment due to their distinctive properties. For instance, delivery of therapeutics using tumor-tropic cells like neutrophils, lymphocytes and mesenchymal stem cells can achieve specific tumor targeting due to the "Trojan Horse" effect. Other circulatory cells like erythrocytes and platelets can greatly improve the circulation time of nanoparticles due to their innate long circulation property. Adipocytes, especially cancer-associated adipocytes, play key roles in tumor development and metabolism, therefore, adipocytes are regarded as promising bio-derived nanoplatforms for anticancer targeted drug delivery. Nanomaterials are important participants in cell-based drug delivery because of their unique physicochemical characteristics. Therefore, the integration of various nanomaterials with different cell types will endow the constructed delivery systems with many attractive properties due to the merits of both. In this review, a number of strategies based on nanomaterial-involved cell-mediated drug delivery systems for cancer treatment will be summarized. This review discusses how nanomaterials can be a benefit to cell-based therapies and how cell-derived carriers overcome the limitations of nanomaterials, which highlights recent advancements and specific biomedical applications based on nanomaterial-mediated, cell-based drug delivery systems.

Bidirectional Interaction Between Cancer Cells and Platelets Provides Potential Strategies for Cancer Therapies

Platelets are essential components in the tumor microenvironment. For decades, clinical data have demonstrated that cancer patients have a high risk of thrombosis that is associated with adverse prognosis and decreased survival, indicating the involvement of platelets in cancer progression. Increasing evidence confirms that cancer cells are able to induce production and activation of platelets. Once activated, platelets serve as allies of cancer cells in tumor growth and metastasis. They can protect circulating tumor cells (CTCs) against the immune system and detachment-induced apoptosis while facilitating angiogenesis and tumor cell adhesion and invasion. Therefore, antiplatelet agents and platelet-based therapies should be developed for cancer treatment. Here, we discuss the mechanisms underlying the bidirectional cancer-platelet crosstalk and platelet-based therapeutic approaches.

Platelet-mediated tumor metastasis mechanism and the role of cell adhesion molecules

Mounting evidence suggests that platelets play an essential role in cancer metastasis. The interactions between platelets and circulating tumor cells (CTCs) promote cancer metastasis. CTCs induce platelet activation and aggregation, and activated platelets gather and protect CTCs from shear stress and natural killer cells. Finally, platelets stimulate CTC anoikis resistance, epithelial-to-mesenchymal transition, angiogenesis, extravasation, and eventually, metastasis. Cell adhesion molecules (CAMs) have been identified as active players during the interaction of CTCs with platelets, but the specific mechanism underlying the contribution of platelet-associated CAMs to CTC metastasis remains unclear. In this review, we introduce the mechanism of platelet-related tumor metastasis and particularly focus on the role of CAMs in it.

Single, Dual, and Triple Antithrombotic Therapy in Cancer Patients with Coronary Artery Disease: Searching for Evidence and Personalized Approaches

Improvement in life expectancy of patients suffering from oncohematologic disorders has turned cancer from an acute into a chronic condition, making the management of comorbidities problematic, especially when it comes to both acute and chronic cardiovascular diseases. Treatment-related adverse events and drug-drug interactions often influence the therapeutic approach of patients with active malignancies and cardiovascular disease. Furthermore, tumor cells and platelets maintain a complex crosstalk that on one hand enhances tumor dissemination and on the other hand induces hemostasis abnormalities. Hence, clinicians should move carefully in the intricate land mines established by patients with active cancer under antithrombotic therapy. To date, there is no consensus on the antithrombotic treatment of patients with cardiovascular diseases and concomitant malignancies. The aim of this review is to collect the available scientific evidence, including the latest clinical trials and guidelines, in order to provide guidance on the management of antithrombotic treatment (both antiplatelet and anticoagulant therapy) in cancer patients with either pre-existent or new-onset coronary artery disease. Randomized-controlled trials on antithrombotic treatment in oncologic populations, which by far have thus far been excluded, have to be promoted to supply recommendations in the oncohematologic setting.

Platelet-Cancer Interplay: Molecular Mechanisms and New Therapeutic Avenues

Although platelets are critically involved in thrombosis and hemostasis, experimental and clinical evidence indicate that platelets promote tumor progression and metastasis through a wide range of physical and functional interactions between platelets and cancer cells. Thrombotic and thromboembolic events are frequent complications in patients with solid tumors. Hence, cancer modulates platelet function by directly inducing platelet-tumor aggregates and triggering platelet granule release and altering platelet turnover. Also, platelets enhance tumor cell dissemination by activating endothelial cell function and recruiting immune cells to primary and metastatic tumor sites. In this review, we summarize current knowledge on the complex interactions between platelets and tumor cells and the host microenvironment. We also critically discuss the potential of anti-platelet agents for cancer prevention and treatment.

Platelet-Mediated Protection of Cancer Cells From Immune Surveillance - Possible Implications for Cancer Immunotherapy

The growing insights in the complex interactions between metastatic cancer-cells and platelets have revealed that platelet tumor cell interactions in the blood stream are an important factor supporting tumor metastasis. An increased coagulability of platelets facilitates the vascular evasion and establishment of solid tumor metastasis. Furthermore, platelets can support an immunosuppressive tumor microenvironment or shield tumor cells directly from engagement of cytotoxic lymphocytes as e.g., natural killer (NK) cells. Platelets are both in the tumor microenvironment and systemically the quantitatively most important source of TGF-β, which is a key cytokine for immunosuppression in the tumor microenvironment. If similar platelet-tumor interactions are of physiological relevance in hematological malignancies remains less well-studied. This might be important, as T- and NK cell mediated graft vs. leukemia effects (GvL) are well-documented and malignant hematological cells have a high exposure to platelets compared to solid tumors. As NK cell-based immunotherapies gain increasing attention as a therapeutic option for patients suffering from hematological and other malignancies, we review the known interactions between platelets and NK cells in the solid tumor setting and discuss how these could also apply to hematological cancers. We furthermore explore the possible implications for NK cell therapy in patients with solid tumors and patients who depend on frequent platelet transfusions. As platelets have a protective and supportive effect on cancer cells, the impact of platelet transfusion on immunotherapy and the combination of immunotherapy with platelet inhibitors needs to be evaluated.

Oral Squamous Cell Carcinoma Is Associated with a Low Thrombosis Risk Due to Storage Pool Deficiency in Platelets

Venous thrombo-embolism (VTE) disease is the second most common cause of mortality in cancer patients, and evaluation and prevention of thrombosis risk is essential. VTE-associated risk varies according to the type of tumor disease. Oral cancer is the most frequent type of head and neck cancer, and it represents approximately 2.1% of all cancers worldwide. Most tumors are squamous cell carcinomas and are mainly due to tobacco and alcohol abuse. VTE risk associated with oral squamous cell carcinoma (OSCC) is low. However, many studies have shown that OSCC has the following biological features of cancers associated with a high thrombosis risk: modified thrombosis and fibrinolysis mechanisms; strong expression of procoagulant proteins; secretion of procoagulant microparticles; and production of procoagulant cytokines. Using an original mouse model of tongue squamous cell carcinoma, our study aimed to clarify this paradoxical situation. First, we showed that OSCC tumors have a pro-aggregatory phenotype and a high local thrombosis risk. Second, we found that tongue tumor mice do not have an elevated systemic thrombosis risk (the risk of an "at distance" thrombosis event such as lower extremity deep venous thrombosis or pulmonary embolism) and even show a reduction in risk. Third, we demonstrated that tongue tumor mice show a reduction in platelet reactivity, which explains the low systemic thrombosis risk. Finally, we found that tongue tumor mice present granule pool deficiency, thereby explaining the reduction in platelet reactivity and systemic thrombosis risk.

Venous Thromboembolism in Cancer Patients Undergoing Chemotherapy: Risk Factors and Prevention

Ambulatory cancer patients undergoing chemotherapy are at a substantial risk for venous thromboembolism (VTE) over the course of therapy and beyond it. Factors accounting for this risk include the activation of extrinsic and intrinsic coagulation pathways, platelet activation, impaired fibrinolysis, use of catheters, infusion of blood products, and thrombogenic potential of several chemotherapeutic drugs. A few stratification models can help identify patients at a higher risk of chemotherapy-associated VTE, who may benefit from preventive strategies. Although low-molecular-weight heparins (LMWHs) effectively reduce the risk of VTE, current guidelines recommend against their routine use. Based on the results of recent randomized controlled clinical trials, the administration of prophylactic doses of the novel direct oral anticoagulants (DOACs) to ambulatory cancer patients undergoing chemotherapy has the potential to offer an effective and safe protection against VTE, obviating the inconveniences of heparins. Except for patients in whom the novel drugs are unsuitable or are contraindicated, in all other patients LMWHs should be replaced by low-dose DOACs.

Hold on or Cut? Integrin- and MMP-Mediated Cell-Matrix Interactions in the Tumor Microenvironment

The tumor microenvironment (TME) has become the focus of interest in cancer research and treatment. It includes the extracellular matrix (ECM) and ECM-modifying enzymes that are secreted by cancer and neighboring cells. The ECM serves both to anchor the tumor cells embedded in it and as a means of communication between the various cellular and non-cellular components of the TME. The cells of the TME modify their surrounding cancer-characteristic ECM. This in turn provides feedback to them via cellular receptors, thereby regulating, together with cytokines and exosomes, differentiation processes as well as tumor progression and spread. Matrix remodeling is accomplished by altering the repertoire of ECM components and by biophysical changes in stiffness and tension caused by ECM-crosslinking and ECM-degrading enzymes, in particular matrix metalloproteinases (MMPs). These can degrade ECM barriers or, by partial proteolysis, release soluble ECM fragments called matrikines, which influence cells inside and outside the TME. This review examines the changes in the ECM of the TME and the interaction between cells and the ECM, with a particular focus on MMPs.

Shotgun proteomics coupled to nanoparticle-based biomarker enrichment reveals a novel panel of extracellular matrix proteins as candidate serum protein biomarkers for early-stage breast cancer detection

Background

The lack of specificity and high degree of false positive and false negative rates when using mammographic screening for detecting early-stage breast cancer is a critical issue. Blood-based molecular assays that could be used in adjunct with mammography for increased specificity and sensitivity could have profound clinical impact. Our objective was to discover and independently verify a panel of candidate blood-based biomarkers that could identify the earliest stages of breast cancer and complement current mammographic screening approaches.

Methods

We used affinity hydrogel nanoparticles coupled with LC-MS/MS analysis to enrich and analyze low-abundance proteins in serum samples from 20 patients with invasive ductal carcinoma (IDC) breast cancer and 20 female control individuals with positive mammograms and benign pathology at biopsy. We compared these results to those obtained from five cohorts of individuals diagnosed with cancer in organs other than breast (ovarian, lung, prostate, and colon cancer, as well as melanoma) to establish IDC-specific protein signatures. Twenty-four IDC candidate biomarkers were then verified by multiple reaction monitoring (LC-MRM) in an independent validation cohort of 60 serum samples specifically including earliest-stage breast cancer and benign controls (19 early-stage (T1a) IDC and 41 controls).

Results

In our discovery set, 56 proteins were increased in the serum samples from IDC patients, and 32 of these proteins were specific to IDC. Verification of a subset of these proteins in an independent cohort of early-stage T1a breast cancer yielded a panel of 4 proteins, ITGA2B (integrin subunit alpha IIb), FLNA (Filamin A), RAP1A (Ras-associated protein-1A), and TLN-1 (Talin-1), which classified breast cancer patients with 100% sensitivity and 85% specificity (AUC of 0.93).

Conclusions

Using a nanoparticle-based protein enrichment technology, we identified and verified a highly specific and sensitive protein signature indicative of early-stage breast cancer with no false positives when assessing benign and inflammatory controls. These markers have been previously reported in cell-ECM interaction and tumor microenvironment biology. Further studies with larger cohorts are needed to evaluate whether this biomarker panel improves the positive predictive value of mammography for breast cancer detection.

Platelet-derived extracellular vesicles regulate cell cycle progression and cell migration in breast cancer cells

Platelets have been extensively implicated in the progression of cancer and platelet-derived extracellular vesicles (PEVs) are gaining growing attention as potential mediators of the platelet-cancer interplay. PEVs are shed from platelet membrane in response to extracellular stimuli and carry important biological signals for intercellular communication. In this study we demonstrate that PEVs specifically bind to different breast cancer cells and elicit cell-specific functional responses. PEVs were massively internalized by the metastatic cell lines MDA-MB-231 and SKBR3 and the ductal carcinoma cell line BT474, but not by the MCF-7 cell line. In SKBR3 cells, PEVs decreased mitochondrial dehydrogenase activities and altered cell cycle progression without affecting cell viability. Conversely, PEVs potently stimulated migration and invasion of MDA-MB-231, without affecting the distribution in the different phases of the cell cycle. In all the analyzed breast cancer cells, PEVs triggered a sustained increase of intracellular Ca²⁺, but only in MDA-MB-231 cells, this was associated to the stimulation of selected signaling proteins implicated in migration, including p38MAPK and myosin light chain. Importantly, inhibition of myosin light chain phosphorylation by a Rho kinase inhibitor prevented PEVs-stimulated migration of MDA-MB-231 cells. Our results demonstrate that PEVs are versatile regulators of cancer cell behavior and elicit a variety of different responses depending on the specific breast cancer cell subtype.

The TICONC (Ticagrelor-Oncology) Study: Implications of P2Y12 Inhibition for Metastasis and Cancer-Associated Thrombosis

Background

In cancer, platelets may facilitate metastatic spread by a number of mechanisms as well as contribute to thrombotic complications. Ticagrelor, a platelet antagonist- that blocks adenosine diphosphate activation of platelet P2Y₁₂ receptors, is widely used in the treatment of cardiovascular disease, but its efficacy in cancer remains unknown.

Objectives

This study sought to evaluate the effect of aspirin and ticagrelor monotherapy, as well as dual antiplatelet therapy, on platelet activation in cancer.

Methods

This study consisted of 2 phases: first, an in vitro study of human platelet−tumor cell interaction; and second, a randomized crossover clinical trial of 22 healthy donors and 16 patients with metastatic breast or colorectal cancer. Platelet activation and inhibition were measured by aggregometry and flow cytometry.

Results

In vitro, tumor cells induced cellular clusters that were predominantly platelet−platelet aggregates. Ticagrelor significantly inhibited formation of large tumor cell-induced platelet−platelet aggregates: 65.4 ± 4.8% to 50.9 ± 5.9% (p = 0.002) and 62.3 ± 3.1% to 48.3 ± 7.3% (p = 0.014) for MCF-7 and HT-29-induced aggregation, respectively. Supporting this finding, cancer patients on ticagrelor had significantly reduced levels of spontaneous platelet aggregation and activation compared with baseline; 14.8 ± 2.7% at baseline to 7.8 ± 2.3% with ticagrelor (p = 0.012).

Conclusions

Our findings suggested that P2Y₁₂ inhibition with ticagrelor might reduce spontaneous platelet aggregation and activation in patients with metastatic cancer and merits further investigation in patients at high risk of cancer-associated thrombosis. (Ticagrelor-Oncology [TICONC] Study; EudraCT: 2014-004049-29)

Ex vivo interaction between blood components and hormone-dependent breast cancer cells induces alterations associated with epithelial-mesenchymal transition and thrombosis

The prevalence of breast cancer is steadily increasing with metastasis and thromboembolic complications identified as the most common causes of death. The acquisition of an aggressive phenotype by hormone-dependent breast cancers is mediated by Transforming Growth Factor Beta 1 (TGF-β₁) expression and is associated with epithelial-mesenchymal transition (EMT) and, potentially, increased propensity for thrombosis. We investigated this phenomenon by assessing the effect of platelet-rich plasma (PRP) and whole blood (WB) on parameters of EMT and hypercoagulation in vitro. MCF-7 breast cancer cells were cultured under standard conditions, followed by co-culture with PRP or WB. Cells were processed for real-time PCR (TGF-β₁ and vimentin), electron microscopy or immunocytochemistry (TGF-β₁). Micrographs were qualitatively assessed, and real-time PCR data analyzed with PAST Statistical Software. The addition of blood components heightened TGF-β₁ immunolocalization and significantly increased corresponding gene expression. Both PRP and WB significantly increased vimentin expression and induced a shape change from a typical epithelial phenotype to a spindle-shape morphology, indicative of EMT. Fibrin fiber, network and plaque formation indicated a hypercoagulatory environment. The results thus show that in preparation for hematogenous metastasis, hormone-dependent breast cancer cells assume an aggressive phenotype associated with EMT, simultaneously increasing the propensity for the formation of thrombo-emboli.

Time-dependent interactions of blood platelets and cancer cells, accompanied by extramedullary hematopoiesis, lead to increased platelet activation and reactivity in a mouse orthotopic model of breast cancer - implications for pulmonary and liver metastasis

Aging has become a significant risk factor for several diseases, including breast cancer.

Platelet activation and platelet-cancer cell aggregate fractions were found to increase with tumor progression in a mouse model of breast cancer. At advanced stages of tumor development, platelets from mice with breast cancer were hyperreactive to low agonist concentrations and hyporeactive to high ones. Platelet activation and reactivity were strongly associated with breast cancer metastasis in the lungs and extramedullary hematopoiesis in the liver. A greater fraction of platelet aggregates was observed in 4T1-injected mice at the advanced stages of breast cancer. In vitro, platelet activation was elevated after incubation with 4T1 cells, and thrombin-stimulated platelets formed aggregates with 4T1 cells. Neither GPIbα, nor GPIIb/IIIa blocking antibodies, were able to affect platelet-cancer cell aggregation in vitro.

The primed circulating platelets became more sensitive to subthreshold stimuli at advanced stages of tumor development, and the formation of platelet-cancer cell aggregates increased with cancer progression. Our findings demonstrate that the age-associated progression of breast cancer cells is connected with increased platelet functioning, and that it can be manifested by the increased number of metastases and extramedullary hematopoiesis in a time-dependent-manner.

Glycosaminoglycans as Tools to Decipher the Platelet Tumor Cell Interaction: A Focus on P-Selectin

Tumor cell–platelet interactions are regarded as an initial crucial step in hematogenous metastasis. Platelets protect tumor cells from immune surveillance in the blood, mediate vascular arrest, facilitate tumor extravasation, growth, and finally angiogenesis in the metastatic foci. Tumor cells aggregate platelets in the bloodstream by activation of the plasmatic coagulation cascade and by direct contact formation. Antimetastatic activities of unfractionated or low molecular weight heparin (UFH/LMWH) can undoubtedly be related to attenuated platelet activation, but molecular mechanisms and contribution of contact formation vs. coagulation remain to be elucidated. Using a set of non-anticoagulant heparin derivatives varying in size or degree of sulfation as compared with UFH, we provide insight into the relevance of contact formation for platelet activation. Light transmission aggregometry and ATP release assays confirmed that only those heparin derivatives with P-selectin blocking capacities were able to attenuate breast cancer cell-induced platelet activation, while pentasaccharide fondaparinux was without effects. Furthermore, a role of P-selectin in platelet activation and signaling could be confirmed by proteome profiler arrays detecting platelet kinases. In this study, we demonstrate that heparin blocks tumor cell-induced coagulation. Moreover, we identify platelet P-selectin, which obviously acts as molecular switch and controls aggregation and secretion of procoagulant platelets.

The "Janus Face" of Platelets in Cancer

Besides their vital role in hemostasis and thrombosis, platelets are also recognized to be involved in cancer, where they play an unexpected central role: They actively influence cancer cell behavior, but, on the other hand, platelet physiology and phenotype are impacted by tumor cells. The existence of this platelet-cancer loop is supported by a large number of experimental and human studies reporting an association between alterations in platelet number and functions and cancer, often in a way dependent on patient, cancer type and treatment. Herein, we shall report on an update on platelet-cancer relationships, with a particular emphasis on how platelets might exert either a protective or a deleterious action in all steps of cancer progression. To this end, we will describe the impact of (i) platelet count, (ii) bioactive molecules secreted upon platelet activation, and (iii) microvesicle-derived miRNAs on cancer behavior. Potential explanations of conflicting results are also reported: Both intrinsic (heterogeneity in platelet-derived bioactive molecules with either inhibitory or stimulatory properties; features of cancer cell types, such as aggressiveness and/or tumour stage) and extrinsic (heterogeneous characteristics of cancer patients, study design and sample preparation) factors, together with other confounding elements, contribute to “the Janus face” of platelets in cancer. Given the difficulty to establish the univocal role of platelets in a tumor, a better understanding of their exact contribution is warranted, in order to identify an efficient therapeutic strategy for cancer management, as well as for better prevention, screening and risk assessment protocols.

Aspirin inhibits platelets from reprogramming breast tumor cells and promoting metastasis

It is now recognized that compounds released from tumor cells can activate platelets, causing the release of platelet-derived factors into the tumor microenvironment. Several of these factors have been shown to directly promote neovascularization and metastasis, yet how the feedback between platelet releasate and the tumor cell affects metastatic phenotype remains largely unstudied. Here, we identify that breast tumor cells secrete high levels of interleukin 8 (IL-8, CXCL8) in response to platelet releasate, which promotes their invasive capacity. Furthermore, we found that platelets activate the Akt pathway in breast tumor cells, and inhibition of this pathway eliminated IL-8 production. We therefore hypothesized inhibiting platelets with aspirin could reverse the prometastatic effects of platelets on tumor cell signaling. Platelets treated with aspirin did not activate the Akt pathway, resulting in reduced IL-8 secretion and impaired tumor cell invasion. Of note, patients with breast cancer receiving aspirin had lower circulating IL-8, and their platelets did not increase tumor cell invasion compared with patients not receiving aspirin. Our data suggest platelets support breast tumor metastasis by inducing tumor cells to secrete IL-8. Our data further support that aspirin acts as an anticancer agent by disrupting the communication between platelets and breast tumor cells.