Effects of cancer on platelets

Tumor-educated platelets

Beyond traditional roles in homeostasis and coagulation, growing evidence suggests that platelets also reflect malignant transformation in cancer. Platelets are present in the tumor microenvironment where they interact with cancer cells. This interaction results in direct and indirect "education" as evident by platelet alterations in adhesion molecules, glycoproteins, nucleic acids, proteins and various receptors. Subsequently, these tumor-educated platelets (TEPs) circulate throughout the body and play pivotal roles in promotion of tumor growth and dissemination. Accordingly, platelet status can be considered a unique blood-based biomarker that can potentially predict prognosis and therapeutic success. Recently, liquid biopsies including TEPs have received much attention as safe, minimally invasive and sensitive alternatives for patient management. Herein, we provide an overview of TEPs and explore their benefits and limitations in cancer.

Platelet-derived microvesicles (PMVs) in cancer progression and clinical applications

Platelet-derived microvesicles (PMVs), the microvesicles with the highest concentration in the bloodstream, play a key role in the regulation of hemostasis, inflammation, and angiogenesis. PMVs have recently been identified as key factors in the link between platelets and cancer. PMVs bind to both cancer cells and nontransformed cells in the microenvironment of the tumor, and then transfer platelet-derived contents to the target cell. These contents have the potential to either stimulate or modulate the target cell's response. PMVs are encased in a lipid bilayer that contains surface proteins and lipids as well as components found inside the PMV. Each of these components participates in known and potential PMV roles in cancer. The complicated roles played by PMVs in the onset, development, and progression of cancer and cancer-related comorbidities are summarized in this study.

Galectin functions in cancer-associated inflammation and thrombosis

Galectins are carbohydrate-binding proteins that regulate many cellular functions including proliferation, adhesion, migration, and phagocytosis. Increasing experimental and clinical evidence indicates that galectins influence many steps of cancer development by inducing the recruitment of immune cells to the inflammatory sites and modulating the effector function of neutrophils, monocytes, and lymphocytes. Recent studies described that different isoforms of galectins can induce platelet adhesion, aggregation, and granule release through the interaction with platelet-specific glycoproteins and integrins. Patients with cancer and/or deep-venous thrombosis have increased levels of galectins in the vasculature, suggesting that these proteins could be important contributors to cancer-associated inflammation and thrombosis. In this review, we summarize the pathological role of galectins in inflammatory and thrombotic events, influencing tumor progression and metastasis. We also discuss the potential of anti-cancer therapies targeting galectins in the pathological context of cancer-associated inflammation and thrombosis.

Hemostasis and cancer: Impact of haemostatic biomarkers for the prediction of clinical outcomes in patients with cancer

Patients with cancer are characterized by a dysregulation of the hemostatic system and systemic hypercoagulability. Different components of the hemostatic system are involved in tumor-promoting mechanisms including primary tumor growth, cancer cell invasion, immune evasion, angiogenesis, and the metastatic process. Therefore, different degrees of systemic hemostatic activation in patients with cancer can reflect distinct underlying biological phenotypes of cancer and seem to correlate with cancer aggressiveness. Peripheral blood levels of hemostatic biomarkers, indicating the activation status of different parts of the hemostatic system including the coagulation cascade, fibrinolytic activity, platelet activation, or endothelial activation, can be used to reflect cancer-associated systemic hypercoagulability. Thereby, hemostatic biomarkers represent promising candidates to investigate as surrogate markers for underlying cancer activity and progression dynamics and therefore as biomarkers for the prediction of clinical outcomes in cancer patients. In the present review, we provide an up-to-date summary of available data on hemostatic biomarkers for prognostication of overall survival and prediction of therapy response in patients with cancer, including specific oncologic treatment settings for potential clinical application. We provide a thorough discussion on potential clinical implementation and current limitations and highlight the most promising emerging biomarkers that might be used to contribute to risk-stratified, personalized oncologic decision making in the future.

Uptake of platelets by cancer cells and recycling of the platelet protein CD42a

BACKGROUND

It is well accepted that the bidirectional crosstalk between platelets and cancer cells promotes tumorigenesis and metastasis. In an early step, cancer cells trigger platelet granule and extracellular vesicle release that is needed to facilitate cancer cell survival in circulation.

OBJECTIVES

To discover the early crosstalk of cancer cells and platelets.

METHODS

Cancer cells were incubated with freshly isolated and stained human platelets. Confocal laser scanning microscopy and flow cytometry was used to visualize and to quantify platelet uptake and the membrane presence of CD42 on cancer cells. Dyngo4a was used to test if platelet uptake is a dynamin-dependent process.

RESULTS

We found a dynamin-dependent uptake of platelets by cancer cells. This is followed by the recycling of the platelet-specific protein CD42a and its incorporation into cancer cells' plasma membrane, which is not a result of platelet RNA transfer by platelet-derived microparticles and exosomes. Time course of platelet uptake follows a sigmoid function revealing that 50% of the cancer cells are positive for platelets after approximately 38 min. Platelet uptake was observed for the tested cancerous cells (A549, MCF-7, and MV3) but not for the non-cancerous cell line 16HBE14o-.

CONCLUSIONS

Our results demonstrate that cancer cells hijack platelets by phagocytosis and recycling of platelet membrane proteins. The uptake of platelets has additional advantages for cancer cells: access to the entire and undiluted platelet proteome, transcriptome, and secretome. These novel findings will allow further mechanistic elucidation and thus help us gain deeper insights into platelet-assisted hematogenous metastasis.

The induction of a mesenchymal phenotype by platelet cloaking of cancer cells is a universal phenomenon

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Platelet cancer cell interactions are a key factor in driving the pro-metastatic phenotype.

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Platelet cancer cell interactions appear to be mediated by 5 key genes which have established roles in metastasis.

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Targeting these mediators of metastasis could improve outcomes for cancer patients.

Tumour metastasis accounts for over 90% of cancer related deaths. The platelet is a key blood component, which facilitates efficient metastasis. This study aimed to understand the molecular mechanisms involved in tumour-platelet cell interactions.

The interaction between cancer cells and platelets was examined in 15 epithelial cell lines, representing 7 cancer types. Gene expression analysis of EMT-associated and cancer stemness genes was performed by RT-PCR. Whole transcriptome analysis (WTA) was performed using Affymetrix 2.0ST arrays on a platelet co-cultured ovarian model.

Platelet adhesion and activation occurred across all tumour types. WTA identified increases in cellular movement, migration, invasion, adhesion, development, differentiation and inflammation genes and decreases in processes associated with cell death and survival following platelet interaction. Increased invasive capacity was also observed in a subset of cell lines. A cross-comparison with a platelet co-cultured mouse model identified 5 common altered genes; PAI-1, PLEK2, CD73, TNC, and SDPR.

Platelet cancer cell interactions are a key factor in driving the pro-metastatic phenotype and appear to be mediated by 5 key genes which have established roles in metastasis. Targeting these metastasis mediators could improve cancer patient outcomes.

Arterial Thrombosis in Cancer Patients: An Update

Cancer is associated with an increased incidence of both venous thromboembolism (VTE) and arterial thrombosis (cardiovascular events and ischemic stroke). Cancer-associated arterial thrombotic events are less well studied than VTE, but increasingly recognized, particularly in specific malignancies and in association with specific anticancer therapies. The pathogenesis of arterial thrombotic events in cancer is complex and involves generation of tumor-associated procoagulant factors and a variety of alterations in platelet function as well as in the coagulation and fibrinolytic systems, and endothelial injury and dysfunction, that combine to produce hypercoagulability. The multifactorial interaction between this prothrombotic state, the individual cardiovascular risk, advanced age and presence of comorbidities, and the specific neoplasm characteristics and therapy, may induce the vascular events. Recent studies based on population databases and prospective or retrospective analyses with prolonged follow-up highlight that cancer patients experience an increased (approximately 1.5-2-fold) risk of both cerebrovascular and cardiovascular events compared with noncancer individuals, which peaks in the time period of the diagnosis of cancer but may persist for years. Beyond the type of cancer, the risk reflects the tumor burden, being higher in advanced stages and metastatic cancers. The occurrence of arterial thromboembolic events is also associated with increased overall mortality. We here present an update of the pathophysiology, risk factors, clinical evidence, and treatment considerations on cancer-associated arterial thrombosis, in the light of the need for specific multidisciplinary prevention and surveillance strategies in this setting, in the frame of cardio-oncology approaches.

Cardiac metastasis causes paradoxical malignant embolism

Background

Embolic events play an important role in clinical everyday practice. Malignant arterial embolism is a rare nevertheless often fatal entity for cardiac, cerebral or systemic ischemia, requiring immediate diagnosis and treatment.

Case

This is a case report of a 65 years‐old female, suffering from pulmonal adenocarcinoma, who was hospitalized due to neurological deficits caused by an acute ischemic stroke, followed by anterior myocardial infarction within 3 days. Diagnostic work‐up revealed metastasis of the pulmonal adenocarcinoma in the right atrium and a patent foramen ovale. Histopathological examination of the coronary embolus verified paradoxical arterial embolism of the pulmonal adenocarcinoma into a coronary vessel and consequently cerebral arteries.

Conclusion

The present case underlines the need for (i), consideration of malignant embolism, (ii) histopathological examination of the embolus to determine its etiology, and (iii) interdisciplinary discussion of individual therapeutic and prevention strategies in cancer patients with cerebral, cardiac or systemic embolic events.

Prognostic value of the systemic immune-inflammation index in non-muscle invasive bladder cancer

Purpose

We assessed the prognostic value of systemic immune-inflammation index (SII) to refine risk stratification of the heterogeneous spectrum of patients with non-muscle-invasive bladder cancer (NMIBC)

Methods

In this multi-institutional cohort, preoperative blood-based SII was retrospectively assessed in 1117 patients with NMIBC who underwent transurethral resection of bladder (TURB) between 1996 and 2007. The optimal cut-off value of SII was determined as 580 using the best Youden index. Cox regression analyses were performed. The concordance index (C-index) and decision curve analysis (DCA) were used to assess the discrimination of the predictive models.

Results

Overall, 309 (28%) patients had high SII. On multivariable analyses, high SII was significantly associated with worse PFS (hazard ratio [HR] 1.84; 95% confidence interval [CI] 1.23–2.77; P = 0.003) and CSS (HR 2.53; 95% CI 1.42–4.48; P = 0.001). Subgroup analyses, according to the European Association of Urology guidelines, demonstrated the main prognostic impact of high SII, with regards to PFS (HR 3.39; 95%CI 1.57–7.31; P = 0.002) and CSS (HR 4.93; 95% CI 1.70–14.3; P = 0.005), in patients with intermediate-risk group; addition of SII to the standard predictive model improved its discrimination ability both on C-index (6% and 12%, respectively) and DCA. In exploratory intergroup analyses of patients with intermediate-risk, the improved discrimination ability was retained the prediction of PFS and CSS.

Conclusion

Preoperative SII seems to identify NMIBC patients who have a worse disease and prognosis. Such easily available and cheap standard biomarkers may help refine the decision-making process regarding adjuvant treatment in patients with intermediate-risk NMIBC.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00345-021-03740-3.

Preoperative plasma D-dimer independently predicts survival in patients with pancreatic ductal adenocarcinoma undergoing radical resection

Background

Elevated plasma D-dimer levels have been reported as an unfavorable prognostic indicator in many solid tumors. However, there are limited relevant studies in pancreatic cancer patients following radical surgery, and the clinical significance remains controversial. The aim of this study was to investigate the clinical and prognostic significance of preoperative plasma D-dimer in patients with pancreatic ductal adenocarcinoma (PDAC) undergoing resection.

Methods

A retrospective analysis was performed on all patients who consecutively underwent radical surgery for PDAC by laparotomy or robotic surgery from December 2011 to December 2018. Baseline clinicopathologic characteristics, preoperative laboratory parameters, and follow-up information were collected. Univariate and multivariate analyses were performed to analyze the prognostic value of preoperative plasma D-dimer.

Results

Among 1351 patients, elevated preoperative plasma D-dimer levels (≥ 0.55 ng/mL) were found in 417 (30.9%) patients. Three hundred twelve (23.09%) underwent minimally invasive robotic pancreatectomy. The median overall survival (OS) of patients with elevated D-dimer levels was 6.3 months shorter than that of patients with normal D-dimer levels (15.0 months vs 21.3 months, p < 0.001). Multivariate analysis showed that elevated D-dimer levels independently predicted poorer OS (hazard ratio, 1.33; 95% confidence interval, 1.17-1.51, p < 0.001). Subgroup analysis demonstrated that D-dimer was a reliable prognostic factor in patients who underwent R0 resection. In addition, integration of D-dimer, carbohydrate antigen 19-9 (CA19-9), and NLR provided a better prognostic model for PDAC patients before operation.

Conclusion

An elevated preoperative plasma D-dimer level was a reliable independent prognostic factor for OS in patients with PDAC undergoing resection. Combination of D-dimer, CA19-9, and NLR can enhance the prognostic accuracy before operation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-021-02281-8.

High pretreatment platelet-to-lymphocyte ratio is related to poor prognosis in the squamous cell carcinoma of the larynx and hypopharynx in male patients

BACKGROUND

There were heterogeneous or even conflicting data regarding the ability of platelet-to-lymphocyte ratio (PLR) for predicting the prognosis of laryngeal/hypopharyngeal squamous cell carcinoma (LHSCC). The discrepancies were found to be largely due to the cutoff value of PLR.

AIMS

The aims of this study were to rationally select an optimal PLR cutoff value and to analyze the relationship between pretreatment PLR and the prognosis.

METHODS

A total of 180 male patients were eligible for this retrospective study. We included another 180 healthy male individuals as controls. The relationship between PLR and age in patients and the controls was determined. The optimal cutoff values of PLR were identified. PLR value was then dichotomized into two categories, and the relationship between PLR and the clinicopathologic parameters were calculated. Kaplan-Meier curves were used to evaluate the overall survival (OS), and the association between PLR and the OS was analyzed.

RESULTS

The linear regression analysis showed a positive correlation between age and PLR in the control group, but not the patients. The optimal cutoff value of PLR was 112.5. The high PLR value group of patients exhibited significantly decreased OS. PLR was related to prognosis, as revealed by the univariate Cox regression.

CONCLUSION

Patients with LHSCC have abnormal high PLR, and a high pretreatment PLR portends adverse survival.

Spontaneous arterial thrombosis in a patient with advanced ovarian clear cell cancer: a case report and literature review

Patients with ovarian cancer are often in a hypercoagulable state and have a high risk of venous thrombosis, including deep vein thrombosis and pulmonary embolism. However, arterial thrombosis is relatively rare in ovarian cancer. We report a case a 46-year-old woman with ovarian clear cell carcinoma who developed arterial and venous thrombosis in the lower extremities as the first manifestation. Her arterial thrombosis-related ischemic symptoms were not responsive to anticoagulant treatment of low-molecular-weight heparin, but improved after neoadjuvant chemotherapy and surgery. Therefore, we hypothesize that the optimal therapy for arterial thrombosis in ovarian cancer is treatment for the underlying disease (i.e., ovarian cancer). A thorough investigation is required to determine the relationships between arterial thrombosis and ovarian cancer and antithrombotic treatments for ovarian cancer related-arterial thrombosis.

Platelets in aging and cancer-"double-edged sword"

Platelets control hemostasis and play a key role in inflammation and immunity. However, platelet function may change during aging, and a role for these versatile cells in many age-related pathological processes is emerging. In addition to a well-known role in cardiovascular disease, platelet activity is now thought to contribute to cancer cell metastasis and tumor-associated venous thromboembolism (VTE) development. Worldwide, the great majority of all patients with cardiovascular disease and some with cancer receive anti-platelet therapy to reduce the risk of thrombosis. However, not only do thrombotic diseases remain a leading cause of morbidity and mortality, cancer, especially metastasis, is still the second cause of death worldwide. Understanding how platelets change during aging and how they may contribute to aging-related diseases such as cancer may contribute to steps taken along the road towards a "healthy aging" strategy. Here, we review the changes that occur in platelets during aging, and investigate how these versatile blood components contribute to cancer progression.

Platelet-T cell aggregates in lung cancer patients: Implications for thrombosis

Platelet-leukocyte aggregates (PLAs) are associated with increased thrombosis risk. The influence of PLA formation is especially important for cancer patients, since thrombosis accounts for approximately 10% of cancer-associated deaths. Our objective was to characterize and quantify PLAs in whole blood samples from lung cancer patients compared to healthy volunteers with the intent to analyze PLA formation in the context of lung cancer-associated thrombosis. Consenting lung cancer patients (57) and healthy volunteers (56) were enrolled at the Dana Cancer Center at the University of Toledo Health Science Campus. Peripheral blood samples were analyzed by flow cytometry. Patient medical history was reviewed through electronic medical records. Most importantly, we found lung cancer patients to have higher percentages of platelet-T cell aggregates (PTCAs) than healthy volunteers among both CD4+ T lymphocyte and CD8+ T lymphocyte populations. Our findings demonstrate that characterization of PTCAs may have clinical utility in differentiating lung cancer patients from healthy volunteers and stratifying lung cancer patients by history of thrombosis.

Soluble levels of sCD40L and s4-1BB are associated with a poor prognosis in elderly patients with colorectal cancer

BACKGROUND AND OBJECTIVES

The prognosis of colorectal cancer (CRC) has improved in the last decades, however, a lower overall survival persists in the elderly. The understanding of immunity changes in the elderly with CRC will allow the emergence of new treatments with higher response rates. 4-1BB and CD40L, an immune checkpoint stimulator, play an important role in T-cell responses and platelets. Our aim was to characterize the soluble levels of CD40L and 4-1BB in CRC elderly patients.

METHODS

A cross-sectional study was performed in 41 patients with CRC and 35 healthy elderly controls. Patients with CRC were divided into three groups according to staging: 13 patients with advanced tumor restricted to the organ (stages II); 16 patients with lymph node metastasis (stage III); and 12 patients with distant metastasis (stage IV).

RESULTS

There were higher levels of soluble s4-1BB and sCD40L in CRC elderly stage II patients when compared with healthy controls (P = .0009 and P < .0001, respectively), stage III patients (P = .008 and P < .0001, respectively) and stage IV patients (P = .007 and P < .0001, respectively).

CONCLUSIONS

We concluded that sCD40L and s4-1BB molecules may be prognostic biomarkers, since the reduction in plasma levels of these molecules was associated with disease progression.

Neutrophil extracellular traps induced by activated platelets contribute to procoagulant activity in patients with colorectal cancer

Patients with colorectal cancer (CRC) are at increased risk of venous thrombosis, but the precise mechanisms of thrombogenesis in CRC remain largely unknown. We aimed to identify the novel role of neutrophil extracellular traps (NETs) in the induction of procoagulant activity (PCA) in CRC, and to evaluate its interactions with platelets and endothelial cells (ECs). In this study, we first showed that the levels of NETs in the peripheral blood of CRC patients were increased in parallel with cancer progression and reached significance in stage II patients compared to healthy subjects. In addition, neutrophils from CRC patients were more prone to produce NETs, resulting in shortened coagulation time, significantly increased thrombin-antithrombin (TAT) complexes and fibrin fibrils compared to healthy controls. Furthermore, platelets from CRC patients stimulated healthy neutrophils to extrude NETs, which could be inhibited by the depletion of HMGB1. Conversely, NETs from CRC patients could also induce the exposure of PS on platelets, leading to markedly enhanced PCA. Importantly, ECs were also converted to a procoagulant phenotype when exposed to NETs from CRC patients. The PCA of NETs-activated platelets or ECs could be inhibited either by the cleavage of NETs with DNase1 or the blockage of histone with activated protein C (APC). Our results reveal the complex interactions between neutrophils, platelets and ECs and their potential role in the hypercoagulable state in CRC. We propose that NETs may provide new therapeutic targets to combat the thrombotic consequences of CRC.

Influence of Resveratrol on the Immune Response

Resveratrol is the most well-known polyphenolic stilbenoid, present in grapes, mulberries, peanuts, rhubarb, and in several other plants. Resveratrol can play a beneficial role in the prevention and in the progression of chronic diseases related to inflammation such as diabetes, obesity, cardiovascular diseases, neurodegeneration, and cancers among other conditions. Moreover, resveratrol regulates immunity by interfering with immune cell regulation, proinflammatory cytokines’ synthesis, and gene expression. At the molecular level, it targets sirtuin, adenosine monophosphate kinase, nuclear factor-κB, inflammatory cytokines, anti-oxidant enzymes along with cellular processes such as gluconeogenesis, lipid metabolism, mitochondrial biogenesis, angiogenesis, and apoptosis. Resveratrol can suppress the toll-like receptor (TLR) and pro-inflammatory genes’ expression. The antioxidant activity of resveratrol and the ability to inhibit enzymes involved in the production of eicosanoids contribute to its anti-inflammation properties. The effects of this biologically active compound on the immune system are associated with widespread health benefits for different autoimmune and chronic inflammatory diseases. This review offers a systematic understanding of how resveratrol targets multiple inflammatory components and exerts immune-regulatory effects on immune cells.

Thrombin Generation and Cancer: Contributors and Consequences

The high occurrence of cancer-associated thrombosis is associated with elevated thrombin generation. Tumour cells increase the potential for thrombin generation both directly, through the expression and release of procoagulant factors, and indirectly, through signals that activate other cell types (including platelets, leukocytes and erythrocytes). Furthermore, cancer treatments can worsen these effects. Coagulation factors, including tissue factor, and inhibitors of coagulation are altered and extracellular vesicles (EVs), which can promote and support thrombin generation, are released by tumour and other cells. Some phosphatidylserine-expressing platelet subsets and platelet-derived EVs provide the surface required for the assembly of coagulation factors essential for thrombin generation in vivo. This review will explore the causes of increased thrombin production in cancer, and the availability and utility of tests and biomarkers. Increased thrombin production not only increases blood coagulation, but also promotes tumour growth and metastasis and as a consequence, thrombin and its contributors present opportunities for treatment of cancer-associated thrombosis and cancer itself.

Akt-mediated platelet apoptosis and its therapeutic implications in immune thrombocytopenia

Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by low platelet count which can cause fatal hemorrhage. ITP patients with antiplatelet glycoprotein (GP) Ib-IX autoantibodies appear refractory to conventional treatments, and the mechanism remains elusive. Here we show that the platelets undergo apoptosis in ITP patients with anti-GPIbα autoantibodies. Consistent with these findings, the anti-GPIbα monoclonal antibodies AN51 and SZ2 induce platelet apoptosis in vitro. We demonstrate that anti-GPIbα antibody binding activates Akt, which elicits platelet apoptosis through activation of phosphodiesterase (PDE3A) and PDE3A-mediated PKA inhibition. Genetic ablation or chemical inhibition of Akt or blocking of Akt signaling abolishes anti-GPIbα antibody-induced platelet apoptosis. We further demonstrate that the antibody-bound platelets are removed in vivo through an apoptosis-dependent manner. Phosphatidylserine (PS) exposure on apoptotic platelets results in phagocytosis of platelets by macrophages in the liver. Notably, inhibition or genetic ablation of Akt or Akt-regulated apoptotic signaling or blockage of PS exposure protects the platelets from clearance. Therefore, our findings reveal pathogenic mechanisms of ITP with anti-GPIbα autoantibodies and, more importantly, suggest therapeutic strategies for thrombocytopenia caused by autoantibodies or other pathogenic factors.

Exosomes play roles in sequential processes of tumor metastasis

Overwhelming evidence demonstrates that exosomes, a series of biologically functional small vesicles of endocytic origin carrying a variety of active constituents, especially tumor-derived exosomes, contribute to tumor progression and metastasis. This review focuses on the specific multifaceted roles of exosomes in affecting sequenced four crucial processes of metastasis, through which cancer cells spread from primary to secondary organs and finally form macroscopic metastatic lesions. First, exosomes modulate the primary tumor sites to assist cancer growth and dissemination. In this part, five main biological events are reviewed, including the transfer of oncogenic constituents, the recruitment and activation of fibroblasts, the induction of angiogenesis, immunosuppression and epithelial-mesenchymal transition (EMT) promotion. In Step 2, we list two recently disclosed mechanisms during the organ-specific homing process: the exosomal integrin model and exosomal epidermal growth factor receptor (EGFR)/miR-26/hepatocyte growth factor (HGF) model. Subsequently, Step 3 focuses on the interactions between exosomes and pre-metastatic niche, in which we highlight the specific functions of exosomes in angiogenesis, lymphangiogenesis, immune modulation and metabolic, epigenetic and stromal reprogramming of pre-metastatic niche. Finally, we summarize the mechanisms of exosomes in helping the metastatic circulating tumor cells escape from immunologic surveillance, survive in the blood circulation and proliferate in host organs.

Survival Mechanisms and Influence Factors of Circulating Tumor Cells

Circulating tumor cells (CTCs) are cancer cells shed from either the primary tumor or its metastases that circulate in the peripheral blood. The CTCs are regarded as the source of tumor recurrence and metastasis and speculated as the indicators of residual tumors, thereby indicating a poor prognosis. Although CTCs play a vital role in tumor metastasis and recurrence, little is known about the underlying survival mechanisms in the blood circulation. The accumulating evidence has revealed that CTCs might survive in the peripheral blood by overcoming the mechanical damage due to shear stress, resistance to anoikis, evasion of immune destruction, and resistance to chemotherapy. The present review addresses the putative survival mechanisms underlying the formation and migration of CTCs according to their biological characteristics and blood microenvironment. In addition, the relationship between CTCs and microenvironment is illustrated, and the influencing factors related to the interactions of CTCs with various components in the peripheral blood are reviewed with respect to the platelets, immune cells, cytokines, and circulating tumor microemboli (CTM). Furthermore, the recent advances in the new treatment strategies targeting the survival mechanisms of CTCs are also discussed.

Arterial thrombosis and cancer

Cancer-associated arterial thrombotic events (ATEs) are increasingly recognized in specific malignancies and in association with the expanding armamentarium of novel chemotherapeutic agents. The improved cancer survival led to cardiovascular complications becoming clinically relevant many years after cancer diagnosis. The pathobiology of ATEs in cancer is complex and the individual patient risk for an ATE entails a multifactorial interaction between the traditional cardiovascular risk factors and comorbidities, the specific malignancy and selected therapy. Treatment with several specific chemotherapeutic agents, immunomodulatory drugs, vascular endothelial growth factor pathway inhibitors, tyrosine kinase inhibitors, and radiotherapy, impart increased risk for ATEs that result from specific therapy-related mechanisms, often involving endothelial injury. Cancer cell-specific prothrombotic properties are important players in the pathogenesis of cancer-associated hypercoagulability. There are distinct biological and molecular processes preferentially activated in specific cancer cells which can trigger ATEs, including platelet activation, increased expression of procoagulants and suppression of fibrinolytic activity. ATEs portend adverse prognosis in cancer patients. Prevention and treatment of cancer-associated ATEs may be improved by greater awareness and careful monitoring for vascular toxicity, aggressive effort to optimize conventional cardiovascular risk factors, and use of antiplatelet and antithrombotic agents in selected patients. These issues are targets for future studies aimed to reduce ATEs in patients with cancer.

Neutrophil-to-lymphocyte and platelet-to-lymphocyte ratios may aid in identifying patients with non-small cell lung cancer and predicting Tumor-Node-Metastasis stages

The present study aimed to identify a high-risk population with non-small cell lung cancer (NSCLC) and to predict TNM stages using the neutrophil-to-lymphocyte ratio (NLR) and the platelet-to-lymphocyte ratio (PLR). This retrospective study included preoperative data of 171 patients and 105 controls. Compared with healthy controls, patients with NSCLC had higher levels of NLR and PLR (NLR, 2.719±0.183 vs. 1.813±0.079, P<0.01; PLR, 135.800±4.778 vs. 112.000±5.651, P<0.01, respectively). The associations between Tumor-Node-Metastasis stages and the aforementioned parameters were detected (both P<0.01). NLR and PLR improved the rate of early diagnosis of NSCLC, particularly for stages III and IV with a higher area under curve value (0.752 and 0.759, respectively) compared with stage I and II NSCLC. In addition, PLR with a T stage-dependent increase may be a potential and independent predictive marker for T stage (P<0.05); the NLR exhibited an N stage-dependent increase (except for stage N3) and was identified as a marker for N stage (P<0.0001). It was subsequently concluded that NLR and PLR are useful biomarkers in the early diagnosis of NSCLC; that these two parameters were capable of indicating advanced stages, III and IV; and that PLR and NLR were independent predictors for T and N stages, respectively.

Neutrophil-to-lymphocyte and platelet-to-lymphocyte ratios may aid in identifying patients with non-small cell lung cancer and predicting Tumor-Node-Metastasis stages

The present study aimed to identify a high-risk population with non-small cell lung cancer (NSCLC) and to predict TNM stages using the neutrophil-to-lymphocyte ratio (NLR) and the platelet-to-lymphocyte ratio (PLR). This retrospective study included preoperative data of 171 patients and 105 controls. Compared with healthy controls, patients with NSCLC had higher levels of NLR and PLR (NLR, 2.719±0.183 vs. 1.813±0.079, P<0.01; PLR, 135.800±4.778 vs. 112.000±5.651, P<0.01, respectively). The associations between Tumor-Node-Metastasis stages and the aforementioned parameters were detected (both P<0.01). NLR and PLR improved the rate of early diagnosis of NSCLC, particularly for stages III and IV with a higher area under curve value (0.752 and 0.759, respectively) compared with stage I and II NSCLC. In addition, PLR with a T stage-dependent increase may be a potential and independent predictive marker for T stage (P<0.05); the NLR exhibited an N stage-dependent increase (except for stage N3) and was identified as a marker for N stage (P<0.0001). It was subsequently concluded that NLR and PLR are useful biomarkers in the early diagnosis of NSCLC; that these two parameters were capable of indicating advanced stages, III and IV; and that PLR and NLR were independent predictors for T and N stages, respectively.

Platelets contribute to the initiation of colitis-associated cancer by promoting immunosuppression

Essentials Inflammation plays a key role in the development of colorectal cancer. Understanding mechanisms of cancer initiation might reveal new anticancer preventive strategy. Hyperactive platelets promote tumor formation by fostering immune evasion of cancer. Platelet inhibition by clopidogrel prevents carcinogenesis by restoring antitumor immunity.

SUMMARY

Background Clinical and experimental evidence support a role for inflammation in the development of colorectal cancer, although the mechanisms are not fully understood. Beyond thrombosis and hemostasis, platelets are key actors in inflammation; they have also been shown to be involved in cancer. However, whether platelets participate in the link between inflammation and cancer is unknown. Objective To investigate the contribution of platelets and platelet-derived proteins to inflammation-elicited colorectal tumor development. Methods We used a clinically relevant mouse model of colitis-associated cancer. Platelet secretion and platelet reactivity to thrombin were assessed at each stage of carcinogenesis. We conducted an unbiased proteomic analysis of releasates of platelets isolated at the pretumoral stage to identify soluble factors that might act on tumor development. Plasma levels of the identified proteins were measured during the course of carcinogenesis. We then treated the mice with clopidogrel to efficiently inhibit platelet release reaction. Results At the pretumoral stage, hyperactive platelets constituted a major source of circulating protumoral serum amyloid A (SAA) proteins. Clopidogrel prevented the early elevation of the plasma SAA protein level, decreased colitis severity, and delayed the formation of dysplastic lesions and adenocarcinoma. Platelet inhibition hindered the expansion and function of immunosuppressive myeloid cells, as well as their infiltration into tumors, but increased the number of tissue CD8+ T cells. Platelets and releasates of platelets from mice with cancer were both able to polarize myeloid cells towards an immunosuppressive phenotype. Conclusions Thus, platelets promote the initiation of colitis-associated cancer by enhancing myeloid cell-dependent immunosuppression. Antiplatelet agents may help to prevent inflammation-elicited carcinogenesis by restoring antitumor immunity.

The Potential Role of Senescence As a Modulator of Platelets and Tumorigenesis

In addition to thrombus formation, alterations in platelet function are frequently observed in cancer patients. Importantly, both thrombus and tumor formation are influenced by age, although the mechanisms through which physiological aging modulates these processes remain poorly understood. In this context, the potential effects of senescent cells on platelet function represent pathophysiological mechanisms that deserve further exploration. Cellular senescence has traditionally been viewed as a barrier to tumorigenesis. However, far from being passive bystanders, senescent cells are metabolically active and able to secrete a variety of soluble and insoluble factors. This feature, known as the senescence-associated secretory phenotype (SASP), may provide senescent cells with the capacity to modify the tissue environment and, paradoxically, promote proliferation and neoplastic transformation of neighboring cells. In fact, the SASP-dependent ability of senescent cells to enhance tumorigenesis has been confirmed in cellular systems involving epithelial cells and fibroblasts, leaving open the question as to whether similar interactions can be extended to other cellular contexts. In this review, we discuss the diverse functions of platelets in tumorigenesis and suggest the possibility that senescent cells might also influence tumorigenesis through their ability to modulate the functional status of platelets through the SASP.

Immunological Consequences of Epithelial-Mesenchymal Transition in Tumor Progression

Microenvironments that tumor cells encounter are different during the stages of cancer progression-primary tumor, metastasis, and at the metastatic site. This suggests potential differences in immune surveillance of primary tumor and metastasis. Epithelial-mesenchymal transition (EMT) is a key reversible process in which cancer cells transition into highly motile and invasive cells for dissemination. Only a tiny proportion successfully metastasize, supporting the notion of metastasis-specific immune surveillance. EMT involves extensive molecular reprogramming of cells conferring many clinically relevant features to cancer cells and affects tumor cell interactions within the tumor microenvironment. We review the impact of tumor immune infiltrates on tumor cell EMT and the consequences of EMT in shaping the immune microenvironment of tumors. The usefulness of EMT as a model to investigate metastasis-specific immune surveillance mechanisms are also explored. Finally, we discuss potential implications of EMT for tumor immunogenicity, as well as current immunotherapies and future strategies.

Platelet-derived Extracellular Vesicles: An Emerging Therapeutic Approach

Extracellular vesicles (EVs) are a newly-discovered way by which cells communicate with their neighbors, as well as transporting cargos which once were considered to be limited by membrane barriers, including membrane proteins, cytosolic proteins and RNA. The discovery of platelet-derived EVs (P-EVs), the most abundant EVs in human blood, has been a very tortuous process. At first, P-EVs were identified as nothing but 'platelet dust', and subsequent research did not progress smoothly because of the limited research techniques to study EVs. Following leaps and bounds of technical progress in studying EVs, more and more attractive features of P-EVs were revealed and they began to be further researched. The aim of this review is to present the latest knowledge about the role of P-EVs in tissue repair and tumor progression. The potential mechanism of P-EVs is emphasized. Then the limitations of the present study and future research directions are discussed.

Platelet "first responders" in wound response, cancer, and metastasis

Platelets serve as "first responders" during normal wounding and homeostasis. Arising from bone marrow stem cell lineage megakaryocytes, anucleate platelets can influence inflammation and immune regulation. Biophysically, platelets are optimized due to size and discoid morphology to distribute near vessel walls, monitor vascular integrity, and initiate quick responses to vascular lesions. Adhesion receptors linked to a highly reactive filopodia-generating cytoskeleton maximizes their vascular surface contact allowing rapid response capabilities. Functionally, platelets normally initiate rapid clotting, vasoconstriction, inflammation, and wound biology that leads to sterilization, tissue repair, and resolution. Platelets also are among the first to sense, phagocytize, decorate, or react to pathogens in the circulation. These platelet first responder properties are commandeered during chronic inflammation, cancer progression, and metastasis. Leaky or inflammatory reaction blood vessel genesis during carcinogenesis provides opportunities for platelet invasion into tumors. Cancer is thought of as a non-healing or chronic wound that can be actively aided by platelet mitogenic properties to stimulate tumor growth. This growth ultimately outstrips circulatory support leads to angiogenesis and intravasation of tumor cells into the blood stream. Circulating tumor cells reengage additional platelets, which facilitates tumor cell adhesion, arrest and extravasation, and metastasis. This process, along with the hypercoagulable states associated with malignancy, is amplified by IL6 production in tumors that stimulate liver thrombopoietin production and elevates circulating platelet numbers by thrombopoiesis in the bone marrow. These complex interactions and the "first responder" role of platelets during diverse physiologic stresses provide a useful therapeutic target that deserves further exploration.

The prognostic value of D-dimer levels in endometrial cancer patients treated with intensity-modulated radiation therapy

Explain the important role of plasma D-dimer in cancers. Plasma D-dimer is increased in various tumors. However, the predictive value of plasma D-dimer is unclear. This study is aimed to evaluate the prognostic value of the D-dimer level in patients managed with intensity-modulated radiation for endometrial cancer. The D-dimer levels of forty patients with endometrial cancer were assessed before (D1) and after (D2) intensity-modulated radiation therapy (IMRT), respectively. The D-dimer level changes (ΔD) were defined as D2 minus D1. Cox regression and log-rank tests were used to evaluate the D-dimer levels in relation to progression free survival (PFS) and overall survival (OS). The OS and PFS of patients with a low D1 were significantly longer than those with a high D1 (P< 0.001, P< 0.001). We saw the similar correlation between D2, PFS and OS (P< 0.001, P< 0.001). Multivariate survival analyses showed that D-dimer was independently associated with OS and PFS in patients with endometrial cancer. The ΔD level was not related to the OS and PFS in endometrial cancer patients. The levels of D-dimer may be considered as an important predictor of PFS and OS in endometrial cancer patients treated with IMRT.

Procoagulant effects of lung cancer chemotherapy: impact on microparticles and cell-free DNA

Lung cancer is the second leading type of cancer, with venous thromboembolism being the second leading cause of death. Studies have shown increased levels of microparticles and cell-free DNA (CFDNA) in cancer patients, which can activate coagulation through extrinsic and intrinsic pathways, respectively. However, the impact of lung cancer chemotherapy on microparticle and/or CFDNA generation is not completely understood. The aim of the study was to study the effects of platinum-based chemotherapeutic agents on generation of procoagulant microparticles and CFDNA in vitro and in vivo. Microparticles were isolated from chemotherapy-treated monocytes, human umbilical vein endothelial cells, or cancer cells. Tissue factor (TF) and phosphatidylserine levels were characterized and thrombin/factor Xa generation assays were used to determine microparticle procoagulant activity. CFDNA levels were isolated from cell supernatants and plasma. A murine xenograft model of human lung carcinoma was used to study the procoagulant effects of TF microparticles and CFDNA in vivo. In vitro, platinum-based chemotherapy induced TF/phosphatidylserine microparticle shedding from A549 and A427 lung cancers cells, which enhanced thrombin generation in plasma in a FVII-dependent manner. CFDNA levels were increased in supernatants of chemotherapy-treated neutrophils and plasma of chemotherapy-treated mice. TF microparticles were elevated in plasma of chemotherapy-treated tumour-bearing mice. Plasma CFDNA levels are increased in chemotherapy-treated tumour-free mice and correlate with increased thrombin generation. In tumour-bearing mice, chemotherapy increases plasma levels of CFDNA and TF/phosphatidylserine microparticles. Platinum-based chemotherapy induces the shedding of TF/phosphatidylserine microparticles from tumour cells and the release of CFDNA from host neutrophils.

Nutritional immunology: function of natural killer cells and their modulation by resveratrol for cancer prevention and treatment

Natural killer (NK) cells as part of the innate immune system represent the first line of defence against (virus-) infected and malignantly transformed cells. The emerging field of nutritional immunology focuses on compounds featuring immune-modulating activities in particular on NK cells, which e.g. can be exploited for cancer prevention and treatment. The plant-based nutrition resveratrol is a ternary hydroxylated stilbene, which is present in many foods and beverages, respectively. In humans it comprises a large variety of distinct biological activities. Interestingly, resveratrol strongly modulates the immune response including the activity of NK cells. This review will give an overview on NK cell functions and summarize the resveratrol-mediated modulation thereof.

Prognostic role of the combination of platelet count and neutrophil-lymphocyte ratio in patients with hypopharyngeal squamous cell carcinoma

Hypopharyngeal squamous cell carcinoma (HPSCC) is an aggressive disease with poor prognosis; but has no established biomarkers on the order of human papilloma virus and p16 in oropharyngeal carcinoma. This study investigated pre-treatment serum markers, including the combination of platelet count and neutrophil-lymphocyte ratio (COP-NLR) as a prognosis predictor in patients with HPSCC treated in our hospital. We retrospectively reviewed electronic medical records of 118 consecutive patients treated with curative intent at our hospital between 2007 and 2013. Of these 118 patients, we enrolled 100 patients for whom we had sufficient data to analyze relationships between clinico-laboratory characteristics and survival, including the prognostic significance of pre-treatment serum markers and previous reported clinical factors. Multivariate analysis of clinico-laboratory characteristics associated COP-NLR with cancer-specific survival, as were lymph node metastases. Kaplan-Meier analysis and log-rank tests showed that the COP-NLR could stratify those patients into three independent groups (P = 0.003). COP-NLR might be a useful predictor of survival in patients with HPSCC.

Prognostic value of pretherapy platelet elevation in oropharyngeal cancer patients treated with chemoradiation

The purpose of this study is to evaluate potential associations between increased platelets and oncologic outcomes in oropharyngeal cancer patients receiving concurrent chemoradiation. A total of 433 oropharyngeal cancer patients (OPC) treated with intensity-modulated radiation therapy (IMRT) with concurrent chemotherapy between 2002 and 2012 were included under an approved IRB protocol. Complete blood count (CBC) data were extracted. Platelet and hemoglobin from the last phlebotomy (PLTpre-chemoRT, Hgbpre-chemoRT ) before start of treatment were identified. Patients were risk-stratified using Dahlstrom-Sturgis criteria and were tested for association with survival and disease-control outcomes. Locoregional control (LRC), freedom from distant metastasis (FDM) and overall survival (OS) were decreased (p < 0.03, p < 0.04 and p < 0.0001, respectively) for patients with PLTpre-chemoRT value of ≥350 × 10(9) /L. Actuarial 5-year locoregional control (LRC) and FDM were 83 and 85% for non-thrombocythemic patients while patient with high platelets had 5-year LRC and FDM of 73 and 74%, respectively. Likewise, 5-year OS was better for patients with normal platelet counts by comparison (76 vs. 57%; p < 0.0001). Comparison of univariate parametric models demonstrated that PLTpre-chemoRT was better among tested models. Multivariate assessment demonstrated improved performance of models which included pretherapy platelet indices. On Bayesian information criteria analysis, the optimal prognostic model was then used to develop nomograms predicting 3-, 5- and 10-year OS. In conclusion, pretreatment platelet elevation is a promising predictor of prognosis, and further work should be done to elucidate the utility of antiplatelets in modifying risk in OPC patients.

Pre-therapeutic fibrinogen levels are of prognostic significance in locally advanced head and neck cancer

OBJECTIVES

The objective of this retrospective study was to clarify the potential prognostic significance of pre-therapeutic fibrinogen levels in head and neck squamous cell carcinoma (HNSCC) patients treated with curative intent by primary radiotherapy (RT) or with postoperative radiotherapy (PORT).

PATIENTS AND METHODS

We retrospectively analyzed data from 347 patients with histologically confirmed locally advanced HNSCC. Analysis was conducted separately for the patient collective treated with PORT (N = 141; 85.1 % AJCC stage III/IV) and for patients treated with primary RT (N = 206; 97.1 % AJCC stage III/IV). Kaplan Meier analyses as well as univariate and multivariate survival analyses were performed to identify factors associated with overall survival (OS).

RESULTS

The most relevant observation was that plasma fibrinogen levels were significantly associated with a reduction of overall survival rates. In the low-fibrinogen (below 411 mg/dL) postoperatively irradiated group, OS rates at 2 and 3 years were 86 and 83 %, and in the high-fibrinogen group 66 and 51 %, respectively. In the RT group with low fibrinogen levels, OS rates after 2 and 3 years were 74 and 53 %, and in the high-fibrinogen group 40 and 22 %, respectively. In multivariate analysis, elevated fibrinogen concentrations were associated with inferior OS in both the postoperatively (HR = 2.5; p = 0.001) as well as in the primarily irradiated (HR = 1.7; p = 0.003) group.

CONCLUSIONS

We conclude from these results that elevated pre-therapeutic fibrinogen may serve as a biomarker associated with worsened prognosis in locally advanced head and neck cancer patients treated by either RT or surgery followed by adjuvant radiotherapy.

Venous thrombosis and cancer: from mouse models to clinical trials

Cancer patients have a ~4 fold increased risk of venous thromboembolism (VTE) compared with the general population and this is associated with significant morbidity and mortality. This review summarizes our current knowledge of VTE and cancer, from mouse models to clinical studies. Notably, the risk of VTE varies depending on the type and stage of cancer. For instance, pancreatic and brain cancer patients have a higher risk of VTE than breast and prostate cancer patients. Moreover, patients with metastatic disease have a higher risk than those with localized tumors. Tumor-derived procoagulant factors and growth factors may directly and indirectly enhance VTE. For example, increased levels of circulating tumor-derived, tissue factor-positive microvesicles may trigger VTE. In a mouse model of ovarian cancer, tumor-derived IL-6 and hepatic thrombopoietin have been linked to increased platelet production and thrombosis. In addition, mouse models of mammary and lung cancer showed that tumor-derived granulocyte colony-stimulating factor causes neutrophilia and activation of neutrophils. Activated neutrophils can release neutrophil extracellular traps (NETs) that enhance thrombosis. Cell-free DNA in the blood derived from cancer cells, NETs and treatment with cytotoxic drugs can activate the clotting cascade. These studies suggest that there are multiple mechanisms for VTE in patients with different types of cancer. Preventing and treating VTE in cancer patients is challenging; the current recommendations are to use low-molecular-weight heparin. Understanding the underlying mechanisms may allow the development of new therapies to safely prevent VTE in cancer patients.

The prothrombotic activity of cancer cells in the circulation

The hemostatic system is often subverted in patients with cancer, resulting in life-threatening venous thrombotic events. Despite the multifactorial and complex etiology of cancer-associated thrombosis, changes in the expression and activity of cancer-derived tissue factor (TF) - the principle initiator of the coagulation cascade - are considered key to malignant hypercoagulopathy and to the pathophysiology of thrombosis. However, many of the molecular and cellular mechanisms coupling the hemostatic degeneration to malignancy remain largely uncharacterized. In this review we discuss some of the tumor-intrinsic and tumor-extrinsic mechanisms that may contribute to the prothrombotic state of cancer, and we bring into focus the potential for circulating tumor cells (CTCs) in advancing our understanding of the field. We also summarize the current status of anti-coagulant therapy for the treatment of thrombosis in patients with cancer.

Information transfer by exosomes: A new frontier in hematologic malignancies

Exosomes are small (30-150 mm) vesicles secreted by all cell types and present in all body fluids. They are emerging as vehicles for delivery of membrane-tethered signaling molecules and membrane enclosed genes to target cells. Exosome-mediated information transfer allows for crosstalk of cells within the hematopoietic system and for interactions between hematopoietic cells and local or distant tissue cells. Exosomes carry physiological signals essential for health and participate in pathological processes, including malignant transformation. In hematologic malignancies, exosomes reprogram the bone marrow microenvironment, creating a niche for abnormal cells and favoring their expansion. The molecular and genetic mechanisms exosomes utilize to shuttle information between cells are currently being examined as are the potential roles exosomes play as biomarkers of disease or future therapeutic targets.