Multifaceted role of cancer educated platelets in survival of cancer cells

Platelet-derived microparticles and their cargos: The past, present and future

All eukaryotic cells can secrete extracellular vesicles, which have a double-membrane structure and are important players in the intercellular communication involved in a variety of important biological processes. Platelets form platelet-derived microparticles (PMPs) in response to activation, injury, or apoptosis. This review introduces the origin, pathway, and biological functions of PMPs and their importance in physiological and pathological processes. In addition, we review the potential applications of PMPs in cancer, vascular homeostasis, thrombosis, inflammation, neural regeneration, biomarkers, and drug carriers to achieve targeted drug delivery. In addition, we comprehensively report on the origin, biological functions, and applications of PMPs. The clinical transformation, high heterogeneity, future development direction, and limitations of the current research on PMPs are also discussed in depth. Evidence has revealed that PMPs play an important role in cell-cell communication, providing clues for the development of PMPs as carriers for relevant cell-targeted drugs. The development history and prospects of PMPs and their cargos are explored in this guidebook.

Secretomics reveals hormone-therapy of breast cancer may induce survival by facilitating hypercoagulation and immunomodulation in vitro

Tumour cell haematogenous dissemination is predicated on molecular changes that enhance their capacity for invasion and preparation of the pre-metastatic niche. It is increasingly evident that platelets play an essential role in this transformation. The systemic nature of signalling molecules and extravascular factors that participate in mediating platelet-tumour cell interactions led to the development of an in vitro co-culture using whole blood and breast tumour cells, allowing us to decipher the impact of hormone-therapy on tumour cells and associated changes in the plasma proteome. Using mass spectrometry, we determined dysregulation of proteins associated with maintaining an invasive tumour phenotype. Tumour changes in genes associated with EMT and survival were documented. This is postulated to be induced via tumour cell interactions with the coagulatory and immune systems. Results highlight tumour cell adaptability to both treatment and blood resulting in a pro-tumorigenic response and a hypercoagulatory state. We illustrate that the breast cancer cell secretome can be altered by hormone-therapy, subject to the tumour subphenotype and linked to platelet activation. More sophisticated co-culture systems are required to recapitulate these interactions to better understand tumorigenesis. Moreover, deeper plasma profiling, using abundant protein depleted and/or vesicle enriched strategies, will likely reveal additional secretory proteins related to tumour cell-platelet interactions.

The role of platelets in the regulation of tumor growth and metastasis: the mechanisms and targeted therapy

Platelets are a class of pluripotent cells that, in addition to hemostasis and maintaining vascular endothelial integrity, are also involved in tumor growth and distant metastasis. The tumor microenvironment is a complex and comprehensive system composed of tumor cells and their surrounding immune and inflammatory cells, tumor-related fibroblasts, nearby interstitial tissues, microvessels, and various cytokines and chemokines. As an important member of the tumor microenvironment, platelets can promote tumor invasion and metastasis through various mechanisms. Understanding the role of platelets in tumor metastasis is important for diagnosing the risk of metastasis and prolonging survival. In this study, we more fully elucidate the underlying mechanisms by which platelets promote tumor growth and metastasis by modulating processes, such as immune escape, angiogenesis, tumor cell homing, and tumor cell exudation, and further summarize the effects of platelet-tumor cell interactions in the tumor microenvironment and possible tumor treatment strategies based on platelet studies. Our summary will more comprehensively and clearly demonstrate the role of platelets in tumor metastasis, so as to help clinical judgment of the potential risk of metastasis in cancer patients, with a view to improving the prognosis of patients.

Neutrophil interactions with T cells, platelets, endothelial cells, and of course tumor cells

Neutrophils sense microbes and host inflammatory mediators, and traffic to sites of infection where they direct a broad armamentarium of antimicrobial products against pathogens. Neutrophils are also activated by damage-associated molecular patterns (DAMPs), which are products of cellular injury that stimulate the innate immune system through pathways that are similar to those activated by microbes. Neutrophils and platelets become activated by injury, and cluster and cross-signal to each other with the cumulative effect of driving antimicrobial defense and hemostasis. In addition, neutrophil extracellular traps are extracellular chromatin and granular constituents that are generated in response to microbial and damage motifs and are pro-thrombotic and injurious. Although neutrophils can worsen tissue injury, neutrophils may also have a role in facilitating wound repair following injury. A central theme of this review relates to how critical functions of neutrophils that evolved to respond to infection and damage modulate the tumor microenvironment (TME) in ways that can promote or limit tumor progression. Neutrophils are reprogrammed by the TME, and, in turn, can cross-signal to tumor cells and reshape the immune landscape of tumors. Importantly, promising new therapeutic strategies have been developed to target neutrophil recruitment and function to make cancer immunotherapy more effective.

Nomogram Based on Platelet-Albumin-Bilirubin for Predicting Tumor Recurrence After Surgery in Alpha-Fetoprotein-Negative Hepatocellular Carcinoma Patients

Purpose

In this study, we developed a nomogram based on the platelet-albumin-bilirubin (PALBI) score to predict recurrence-free survival (RFS) after curative resection in alpha-fetoprotein (AFP)-negative (≤20 ng/mL) hepatocellular carcinoma (HCC) patients.

Patients and Methods

A total of 194 pathologically confirmed AFP-negative HCC patients were retrospectively analyzed. Univariate and multivariate Cox regression analyses were performed to screen the independent risk factors associated with RFS, and a nomogram prediction model for RFS was established according to the independent risk factors. The receiver operating characteristic (ROC) curve and the C-index were used to evaluate the accuracy and the efficacy of the model prediction. The correction curve was used to assess the calibration of the prediction model, and decision curve analysis was performed to evaluate the clinical application value of the prediction model.

Results

PALBI score, MVI, and tumor size were independent risk factors for postoperative tumor recurrence (P < 0.05). A nomogram prediction model based on the independent predictive factors was developed to predict RFS, and it achieved a good C-index of 0.704 with an area under the ROC curve of 0.661 and the sensitivity was 73.2%. Patients with AFP-negative HCC could be divided into the high-risk group or the low-risk group by the risk score calculated by the nomogram, and there was a significant difference in RFS between the two groups (P < 0.05). Decision curve analysis (DCA) showed that the nomogram increased the net benefit in predicting the recurrence of AFP-negative HCC and exhibited a wider range of threshold probabilities than the independent risk factors (PALBI score, MVI, and tumor size) by risk stratification.

Conclusion

The nomogram based on the PALBI score can predict RFS after curative resection in AFP-negative HCC patients and can help clinicians to screen out high-risk patients for early intervention.

The role and pharmacological properties of P2Y12 receptor in cancer and cancer pain

The G protein-coupled P2Y12 receptor (P2Y12R) was cloned in platelets and found to play a key role in maintaining platelet function in hemostasis and thrombosis, and these effects could be mediated by the P2Y12R. However, it has recently been found that P2Y12R-mediated the progression of tumor through interactions between platelets and tumor and stromal cells, as well as through products secreted by platelets. During tumor progression, tumor cells or other cells in the tumor microenvironment (such as immune cells) can secrete large amounts of ATP into the extracellular matrix, and extracellular ATP can be hydrolyzed into ADP. ADP is a P2Y12R activator and plays an important regulatory role in the proliferation and metastasis of tumor cells. P2Y12R is involved in platelet-cancer cell crosstalk and become a potential target for anticancer therapy. Moreover, tumor progression can induce pain, which seriously affects the quality of life of patients. P2Y12R is expressed in microglia and mediates the activities of microglial and participates in the occurrence of cancer pain. Conversely, inhibiting P2Y12R activation and down-regulating its expression has the effect of inhibiting tumor progression and pain. Therefore, P2Y12R can be a common therapeutic target for both. In this article, we explored the potential link between P2Y12R and cancer, discussed the intrinsic link of P2Y12R in cancer pain and the pharmacological properties of P2Y12R antagonists in the treatment of both.

A narrative review for platelets and their RNAs in cancers: New concepts and clinical perspectives

Recent years have witnessed a growing body of evidence suggesting that platelets are involved in several stages of the metastatic process via direct or indirect interactions with cancer cells, contributing to the progression of neoplastic malignancies. Cancer cells can dynamically exchange components with platelets in and out of blood vessels, and directly phagocytose platelets to hijack their proteome, transcriptome, and secretome, or be remotely regulated by metabolites or microparticles released by platelets, resulting in phenotypic, genetic, and functional modifications. Moreover, platelet interactions with stromal and immune cells in the tumor microenvironment lead to alterations in their components, including the ribonucleic acid (RNA) profile, and complicate the impact of platelets on cancers. A deeper understanding of the roles of platelets and their RNAs in cancer will contribute to the development of anticancer strategies and the optimization of clinical management. Encouragingly, advances in high-throughput sequencing, bioinformatics data analysis, and machine learning have allowed scientists to explore the potential of platelet RNAs for cancer diagnosis, prognosis, and guiding treatment. However, the clinical application of this technique remains controversial and requires larger, multicenter studies with standardized protocols. Here, we integrate the latest evidence to provide a broader insight into the role of platelets in cancer progression and management, and propose standardized recommendations for the clinical utility of platelet RNAs to facilitate translation and benefit patients.

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.

Proteomics profiling identifies extracellular vesicles' cargo associated with tumour cell induced platelet aggregation

Background

Cancer patients have an increased risk of developing venous thromboembolism, with up to 30% dying within a month of their development. Some cancer cells are known to induce platelet aggregation, and this interaction is understood to contribute to thrombosis and haematogenous metastasis. Many researchers have reported on extracellular vesicles (EVs) released from platelets. However, less is known about how cancer cells’ EVs may affect platelet function. Here EVs released by triple-negative breast cancer (TNBC) cell line variants were extensively investigated in this regard.

Methods

EVs were separated from conditioned media of TNBC Hs578T and Hs578Ts(i)₈ cells using filtration and ultracentrifugation and were characterised by nanoparticle tracking analysis, immunoblots, and transmission electron microscopy. Blood samples from consenting donors were procured, and their platelets collected by differential centrifugation. Light transmission aggregometry and optical microscopy evaluated the potential interaction of TNBC cells and their EVs with platelets. Global proteomic analysis was performed on the EVs, by in-solution digestion and mass spectrometry. Data analysis included the use of Perseus, FunRich, and Vesiclepedia. Immunoblotting was used as a secondary method to investigate some key EV cargo proteins identified by the global proteomics approach.

Results

Both TNBC cell variants induced platelet aggregation. Increasing cell numbers significantly reduced the time taken for platelet aggregation to occur. EVs released by the cells also resulted in platelet aggregation. The time to induce platelet aggregation was EV dose-dependent. Proteomics profiling and immunoblotting of the EVs’ cargo identified candidate proteins (including uPAR and PDGFRβ) that may be involved during this process.

Conclusions

TNBC cells induce platelet aggregation. Furthermore, the cell-free EVs induced this undesirable effect. A number of EV cargo proteins were identified that may be relevant as therapeutic targets.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-10068-7.

Pancreatic Cancer Cells Induce MicroRNA Deregulation in Platelets

Pancreatic cancer is a pathology with a high mortality rate since it is detected at advanced stages, so the search for early-stage diagnostic biomarkers is essential. Liquid biopsies are currently being explored for this purpose and educated platelets are a good candidate, since they are known to present a bidirectional interaction with tumor cells. In this work, we analyzed the effects of platelets on cancer cells’ viability, as determined by MTT, migration using transwell assays, clonogenicity in soft agar and stemness by dilution assays and stem markers’ expression. We found that the co-culture of platelets and pancreatic cancer cells increased the proliferation and migration capacity of BXCP3 cells, augmented clonogenicity and induced higher levels of Nanog, Sox2 and Oct4 expression. As platelets can provide horizontal transfer of microRNAs, we also determined the differential expression of miRNAs in platelets obtained from a small cohort of pancreatic cancer patients and healthy subjects. We found clear differences in the expression of several miRNAs between platelets of patients with cancer healthy subjects. Moreover, when we analyzed microRNAs from the platelets of the pancreatic juice and blood derived from each of the cancer patients, interestingly we find differences between the blood- and pancreatic juice-derived platelets suggesting the presence of different subpopulations of platelets in cancer patients, which warrant further analysis.

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.

CRISPR/Cas9 application in cancer therapy: a pioneering genome editing tool

The progress of genetic engineering in the 1970s brought about a paradigm shift in genome editing technology. The clustered regularly interspaced short palindromic repeats/CRISPR associated protein 9 (CRISPR/Cas9) system is a flexible means to target and modify particular DNA sequences in the genome. Several applications of CRISPR/Cas9 are presently being studied in cancer biology and oncology to provide vigorous site-specific gene editing to enhance its biological and clinical uses. CRISPR's flexibility and ease of use have enabled the prompt achievement of almost any preferred alteration with greater efficiency and lower cost than preceding modalities. Also, CRISPR/Cas9 technology has recently been applied to improve the safety and efficacy of chimeric antigen receptor (CAR)-T cell therapies and defeat tumor cell resistance to conventional treatments such as chemotherapy and radiotherapy. The current review summarizes the application of CRISPR/Cas9 in cancer therapy. We also discuss the present obstacles and contemplate future possibilities in this context.

Targeted Inhibition of Tumor Inflammation and Tumor-Platelet Crosstalk by Nanoparticle-Mediated Drug Delivery Mitigates Cancer Metastasis

Sowing malignant cells (the "seeds" of metastasis) to engraft secondary sites requires a conducive premetastatic niche (PMN, the "soil" of metastasis). Inflammation and tumor associated platelet (TAP) has been hijacked by primary tumors to induce PMN "soil" in distant organs, as well as facilitate the dissemination of "seeds". This study reports a combinatory strategy with activated platelet-targeting nanoparticles to aim at the dynamic process of entire cancer metastasis, which exerts robust antimetastasis efficacy by simultaneously inhibiting tumor inflammation and tumor-platelet crosstalk. Our results reveals that the PSN peptide (a P-selectin-targeting peptide) modification enriched the accumulation of nanoparticles in primary tumor, pulmonary PMN, and metastases via capturing activated platelet. Such characteristics contribute to the efficient inhibition on almost every crucial and consecutive step of the metastasis cascade by retarding epithelial-mesenchymal transition (EMT) progression within tumors, specifically blocking the tumor-platelet crosstalk to remove the platelets "protective shield" around disseminated "seeds", and reversing the inflammatory microenvironment to interfere with the "soil" formation. Consisting of inflammation inhibiting and TAP impeding nanoparticles, this approach prominently reduces various metastasis in abscopal lung, including spontaneous metastasis, disseminated tumor cells metastasis, and post-operative metastasis. This work provides a generalizable nanoplatform of parallel inflammation disturbance and tumor-TAP crosstalk blockade to resist metastatic tumors.

Platelet CLEC2-Podoplanin Axis as a Promising Target for Oral Cancer Treatment

Cancer tissues are not just simple masses of malignant cells, but rather complex and heterogeneous collections of cellular and even non-cellular components, such as endothelial cells, stromal cells, immune cells, and collagens, referred to as tumor microenvironment (TME). These multiple players in the TME develop dynamic interactions with each other, which determines the characteristics of the tumor. Platelets are the smallest cells in the bloodstream and primarily regulate blood coagulation and hemostasis. Notably, cancer patients often show thrombocytosis, a status of an increased platelet number in the bloodstream, as well as the platelet infiltration into the tumor stroma, which contributes to cancer promotion and progression. Thus, platelets function as one of the important stromal components in the TME, emerging as a promising chemotherapeutic target. However, the use of traditional antiplatelet agents, such as aspirin, has limitations mainly due to increased bleeding complications. This requires to implement new strategies to target platelets for anti-cancer effects. In oral squamous cell carcinoma (OSCC) patients, both high platelet counts and low tumor-stromal ratio (high stroma) are strongly correlated with increased metastasis and poor prognosis. OSCC tends to invade adjacent tissues and bones and spread to the lymph nodes for distant metastasis, which is a huge hurdle for OSCC treatment in spite of relatively easy access for visual examination of precancerous lesions in the oral cavity. Therefore, locoregional control of the primary tumor is crucial for OSCC treatment. Similar to thrombocytosis, higher expression of podoplanin (PDPN) has been suggested as a predictive marker for higher frequency of lymph node metastasis of OSCC. Cumulative evidence supports that platelets can directly interact with PDPN-expressing cancer cells via C-type lectin-like receptor 2 (CLEC2), contributing to cancer cell invasion and metastasis. Thus, the platelet CLEC2-PDPN axis could be a pinpoint target to inhibit interaction between platelets and OSCC, avoiding undesirable side effects. Here, we will review the role of platelets in cancer, particularly focusing on CLEC2-PDPN interaction, and will assess their potentials as therapeutic targets for OSCC treatment.

Tumor-Educated Platelets: A Review of Current and Potential Applications in Solid Tumors

In this current era of precision medicine, liquid biopsy poses a unique opportunity for an easily accessible, comprehensive molecular profile that would allow for the identification of therapeutic targets and sequential monitoring. Solid tumors are definitively diagnosed by analyzing primary tumor tissue, but surgical sampling is not always sufficient to generate a comprehensive genetic fingerprint at the time of diagnosis, or an appropriate means for continued monitoring. Platelets are known to have a dynamic, bidirectional relationship with tumors, acting beyond their role of hemostasis. Tumor-educated platelets (TEP) are modified by the tumor in multiple ways and act as a carrier and protector of metastasis. Data so far have shown that the mRNA in TEP can be harnessed for cancer diagnostics, with many potential applications.

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.

Platelet infiltration predicts survival in postsurgical colorectal cancer patients

Platelets promote tumor growth and metastasis in several tumor types. Recent research has found platelets can extravasate and infiltrate into the tumor stroma and interact with the tumor microenvironment. The prognostic role of platelet infiltration in colorectal cancer (CRC) remains controversial. A pan-cancer survival analysis was performed to find the potential prognostic value of platelet infiltration in patients with cancer. A survival analysis and a nomogram prognostic model were established to further confirm the results with data from our center. The correlations between patient outcomes and tumor-infiltrating platelets (TIPs) were identified by immunohistochemical staining for CD42b. The prognostic accuracy and discriminative ability of the nomogram were determined by the concordance index (C-index) and a calibration curve. The pan-cancer survival analysis showed platelet infiltration can lead to a poor prognosis in patients with several types of cancers, including CRC. Platelet infiltration was associated with overall survival (OS) and disease-free survival (DFS) in both primary and validation cohorts. The C-index values of the nomogram for predicting OS and DFS were 0.774 and 0.769, respectively, which were higher than that of the TNM staging system alone. Our study found platelet infiltration has a potential prognostic value regarding postsurgical survival in CRC patients. The proposed nomogram resulted in a more accurate prognostic prediction for postsurgical CRC patients.

Platelets and tumor-associated RNA transfer

Until recently, the nucleic acid content of platelets was considered to be fully determined by their progenitor megakaryocyte. However, it is now well understood that additional mediators (eg, cancer cells) can intervene, thereby influencing the RNA repertoire of platelets. Platelets are highly dynamic cells that are able to communicate and influence their environment. For instance, platelets have been involved in various steps of cancer development and progression by supporting tumor growth, survival, and dissemination. Cancer cells can directly and/or indirectly influence platelet RNA content, resulting in tumor-mediated "education" of platelets. Alterations in the tumor-educated platelet RNA profile have been described as a novel source of potential biomarkers. Individual platelet RNA biomarkers as well as complex RNA signatures may be used for early detection of cancer and treatment monitoring. Here, we review the RNA transfer occurring between cancer cells and platelets. We explore the potential use of platelet RNA biomarkers as a liquid biopsy biosource and discuss methods to evaluate the transcriptomic content of platelets.

Platelet transfusion for cancer secondary thrombocytopenia: Platelet and cancer cell interaction

Chemoradiotherapy and autoimmune disorder often lead to secondary thrombocytopenia in cancer patients, and thus, platelet transfusion is needed to stop or prevent bleeding. However, the effect of platelet transfusion remains controversial for the lack of agreement on transfusion strategies. Before being transfused, platelets are stored in blood banks, and their activation is usually stimulated. Increasing evidence shows activated platelets may promote metastasis and the proliferation of cancer cells, while cancer cells also induce platelet activation. Such a vicious cycle of interaction between activated platelets and cancer cells is harmful for the prognosis of cancer patients, which results in an increased tumor recurrence rate and decreased five-year survival rate. Therefore, it is important to explore platelet transfusion strategies, summarize mechanisms of interaction between platelets and tumor cells, and carefully evaluate the pros and cons of platelet transfusion for better treatment and prognosis for patients with cancer with secondary thrombocytopenia.

Platelet Activation In Situ in Breasts at High Risk of Cancer: Relationship with Mammographic Density and Estradiol

CONTEXT

High mammographic density in postmenopausal women is an independent risk factor for breast cancer by undetermined mechanisms. No preventive therapy for this risk group is available. Activated platelets release growth factors that modulate the microenvironment into a protumorigenic state. Estrogens may affect the risk of breast cancer and platelet function. Whether platelets are activated in situ in breast cancer or in normal breast tissue at high risk of breast cancer and the association to estradiol remains elusive.

OBJECTIVE

To investigate whether platelets are activated in situ in breast cancers and in dense breast tissue of postmenopausal women and explore correlations between estradiol, released platelet factors, and inflammatory proteins.

SETTING AND DESIGN

Sampling of in vivo proteins was performed using microdialysis in a total of 71 women: 10 with breast cancer, 42 healthy postmenopausal women with different breast densities, and 19 premenopausal women.

RESULTS

Our data demonstrate increased levels of coagulation factors in dense breast tissue similar to that found in breast cancers, indicating excessive platelet activation. Premenopausal breasts exhibited similar levels of coagulation factors as postmenopausal dense breasts. Out of 13 coagulations factors that were upregulated in dense breasts, 5 exhibited significant correlations with estradiol, both locally in the breast and systemically. In breast tissue, positive correlations between coagulation factors and key inflammatory proteins and matrix metalloproteinases were detected.

CONCLUSIONS

Breast density, not estradiol, is the major determinant of local platelet activation. Inactivation of platelets may be a therapeutic strategy for cancer prevention in postmenopausal women with dense breasts.

Platelet supernatant with longer storage inhibits tumor cell growth

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Huayu Wan Prevents Lewis Lung Cancer Metastasis in Mice via the Platelet Pathway

Objective

To study the mechanism of Huayu Wan on the metastasis of Lewis lung cancer in mice via the platelet pathway.

Method

Construction of the lung metastasis model by injection of Lewis cells through the tail vein. The next day, 72 mice were randomly divided into the Huayu Wan group (HYW), the aspirin group, the control group, and the normal group . Treatment was given for 5 days per week for a total of 16 days. The size and distribution of lung metastases were observed. Thromboelastography was used to detect platelet function, flow cytometry was used to analyze platelet activation, and ELISA was used to detect platelet tumor metastasis-related factor expression.

Result

Lung weight in the control group was significantly higher than that in the HYW group (P < 0.05). The distribution of lung metastases in the control group was obviously more than that in the HYW group. The thromboelastogram showed that the R value of the control group was significantly lower than the normal group, while the R values of the HYW and aspirin groups were higher than the control group (P < 0.05). Flow cytometry analysis showed that the expression of CD62P in platelet-rich plasma in the control group was significantly higher than that in the normal group, while the expression of CD62P in the HYW and aspirin groups was lower than that in the control group (P < 0.05). In addition, ELISA showed that the expression of VEGF, bFGF, and CD62P in serum of the HYW group was significantly decreased than the control group (P < 0.05), and the expression of VEGF and bFGF in serum of the aspirin group was significantly decreased than the control group (P < 0.05).

Conclusion

The mechanism of Huayu Wan inhibiting the metastasis of lung cancer in mice may be related to the improvement of blood hypercoagulability, the inhibition of platelet activation, and the expression of VEGF, bFGF, and CD62P.

The aegis: platelets as biomarkers of tumor progression

There is increasing awareness that platelets play a significant role in creating a hypercoagulable environment that mediates tumor progression, beyond their classical hemostatic function. Platelets have heterogenic responses to agonists, and differential release and uptake of bioactive molecules may be manipulated via reciprocal cross-talk with cells of the tumor microenvironment. Platelets thus promote tumor progression by enhancing tumor growth, promoting the development of tumor-associated vasculature and encouraging invasion. In the metastatic process, platelets form the shield that protects tumor cells from high-velocity forces and immunosurveillance, while ensuring the establishment of the pre-metastatic niche. This review presents the complexity of these concepts, considering platelets as biomarkers for diagnosis, prognosis and potentially as therapeutic targets in cancer.

Mean platelet counts are relatively decreased with malaria but relatively increased with endemic Burkitt Lymphoma in Uganda, Tanzania, and Kenya

Platelet counts are decreased in Plasmodium falciparum malaria, which is aetiologically linked with endemic Burkitt lymphoma (eBL). However, the pattern of platelet counts in eBL cases is unknown. We studied platelet counts in 582 eBL cases and 2 248 controls enrolled in a case-control study in Uganda, Tanzania and Kenya (2010-2016). Mean platelet counts in controls or eBL cases with or without malaria-infection in controls versus eBLcases were compared using Student's t-test. Odds ratios (ORs) and two-sided 95% confidence intervals (95% CIs) were estimated using multiple logistic regression, controlling for age, sex, haemoglobin and white blood cell counts. Platelets were decreased with malaria infection in the controls [263 vs. 339 × 10⁹ platelets/l, P < 0·0001; adjusted OR (aOR) = 3·42, 95% CI: 2·79-4·18] and eBL cases (314 vs. 367 × 10⁹ platelets/l, P-value = 0·002; aOR = 2·36, 95% CI: 1·49-3·73). Unexpectedly, platelets were elevated in eBL cases versus  controls in overall analyses (mean: 353 vs. 307 × 10⁹ platelets/l, P < 0·0001; aOR = 1·41; 95% CI: 1·12-1·77), and when restricted to malaria-positive (mean 314 vs. 263 × 10⁹ platelets/l, P < 0·0001; OR = 2·26; 95% CI: 1·56-3·27) or malaria-negative (mean 367 vs. 339 × 10⁹ platelets/l, P < 0·001; OR = 1·46; 95% CI: 1·17-1·83) subjects. Platelets were decreased with malaria infection in controls and eBL cases but elevated with eBL.

Tumor-educated platelet as liquid biopsy in lung cancer patients

Lung cancer is the most frequent cancer for males and third most frequent cancer for females. Targeted therapy drugs based on molecular alterations, such as angiogenesis inhibitors, epidermal growth factor receptor (EGFR) inhibitors, and anaplastic lymphoma kinase (ALK) inhibitors are important part of treatment of NSCLC. However, the quality of the available tumor biopsy and/or cytology material is sometimes not adequate to perform the necessary molecular testing, which has prompted the search for alternatives. This review examines the use of tumor-educated platelet (TEP) as a liquid biopsy in lung cancer patients. The development of sensitive and accurate techniques have made it possible to detect the specific genetic alterations for which targeted therapies are already available. Liquid biopsy offers opportunities to detect resistance mechanisms at an early stage. To conclude, tumor-educated platelet has the potential to be used as liquid biopsy for a variety of clinical and investigational applications.

Delivery of platelet TPM3 mRNA into breast cancer cells via microvesicles enhances metastasis

Platelets are implicated in the pathophysiology of breast and other cancers through their role in exchanging biomolecules with tumor cells in the tumor microenvironment. Such exchange results in tumor‐educated platelets with altered RNA expression profiles. Multiple lines of evidence indicate that platelet RNA profiles may be suitable as diagnostic biomarkers for cancer‐related biological processes. In this study, we characterized the gene expression signatures of platelets in breast cancer (BC) by high‐throughput sequencing and quantitative real‐time RT‐PCR. Our results indicate that the expression of TPM3 (tropomyosin 3) mRNA is significantly elevated in platelets from patients with BC compared with age‐matched healthy control subjects. Furthermore, up‐regulation of TPM3 mRNA in platelets was found to be significantly correlated with metastasis in patients with BC. Finally, we report that platelet TPM3 mRNA is delivered into BC cells through microvesicles and leads to enhanced migrative phenotype of BC cells. In summary, our findings suggest that the transfer of platelet TPM3 mRNA into cancer cells via microvesicles promotes cancer cell migration, and thus platelet‐derived TPM3 mRNA may be a suitable biomarker for early diagnosis of metastatic BC.

Platelets are implicated in the pathophysiology of breast and other cancers through their role in exchanging biomolecules with tumor cells in the tumor microenvironment. In this study, we found that platelet TPM3 (tropomyosin 3) mRNA can be delivered into cancer cells via microvesicles to promote cancer cell migration. Platelet‐derived TPM3 mRNA may be a suitable biomarker for early diagnosis of metastatic breast cancer.