Modulation of natural killer cell anti-tumor reactivity by platelets

The clinical significance of preoperative plasma fibrinogen level and platelet count in resectable esophageal squamous cell carcinoma

Background

Patients with malignant disease frequently present with activated coagulation pathways, which are potentially associated with tumor progression and prognosis. The aims of the study were to investigate the clinical significance of preoperative plasma fibrinogen level and platelet count in esophageal squamous cell carcinoma (ESCC) treated by curative surgery.

Methods

A total of 119 patients with ESCC treated by curative surgery in Qilu Hospital of Shandong University were included in the study.

Results

The preoperative plasma fibrinogen levels in the patients with ESCC ranged from 2.2 to 6.91 g/L (mean ± SD, 3.85 ± 0.95 g/L). The incidence of hyperfibrinogenemia was 43.7% (52/119, cut-off value 4.0 g/L). Hyperfibrinogenemia was found to be positively correlated with increased tumor length (P = 0.027), increased depth of invasion (P = 0.013), advanced pathological stages (P = 0.011), and disease recurrence (P = 0.026). The platelet counts ranged from 78 × 10⁹/L to 936 × 10⁹/L (mean ± SD, 254.51 ± 89.26 × 10⁹/L). The incidence of thrombocytosis was 20.2% (24/119, cut-off value 300 × 10⁹/L). Thrombocytosis was more frequently seen in male gender (P = 0.029) and non-smokers (P = 0.008). Plasma fibrinogen levels were significantly correlated with platelet counts (r = 0.018, P = 0.048). Hyperfibrinogenemia was significantly associated with poor disease-free (P = 0.009, hazard ratio (HR) = 1.784, 95% confidence interval (CI) = 1.153 to 2.761) and overall (P = 0.003, HR = 1.992, 95% CI = 1.259 to 3.152) survivals in univariate analysis, but not an independent prognostic indicator in multivariate analysis. Thrombocytosis was not significantly associated with disease-free (P = 0.765, HR = 0.918, 95% CI = 0.524 to 1.608) or overall (P = 0.809, HR = 1.072, 95% CI = 0.618 to 1.891) survivals in univariate analysis.

Conclusions

The study suggested that hyperfibrinogenemia is a valuable predictor for disease progression in ESCC. Anticoagulation therapy might be considered to control cancer progression in future studies.

Platelets enhance tissue factor protein and metastasis initiating cell markers, and act as chemoattractants increasing the migration of ovarian cancer cells

Background

An increase in circulating platelets, or thrombocytosis, is recognized as an independent risk factor of bad prognosis and metastasis in patients with ovarian cancer; however the complex role of platelets in tumor progression has not been fully elucidated. Platelet activation has been associated with an epithelial to mesenchymal transition (EMT), while Tissue Factor (TF) protein expression by cancer cells has been shown to correlate with hypercoagulable state and metastasis. The aim of this work was to determine the effect of platelet-cancer cell interaction on TF and “Metastasis Initiating Cell (MIC)” marker levels and migration in ovarian cancer cell lines and cancer cells isolated from the ascetic fluid of ovarian cancer patients.

Methods

With informed patient consent, ascitic fluid isolated ovarian cancer cells, cell lines and ovarian cancer spheres were co-cultivated with human platelets. TF, EMT and stem cell marker levels were determined by Western blotting, flow cytometry and RT-PCR. Cancer cell migration was determined by Boyden chambers and the scratch assay.

Results

The co-culture of patient-derived ovarian cancer cells with platelets causes: 1) a phenotypic change in cancer cells, 2) chemoattraction and cancer cell migration, 3) induced MIC markers (EMT/stemness), 3) increased sphere formation and 4) increased TF protein levels and activity.

Conclusions

We present the first evidence that platelets act as chemoattractants to cancer cells. Furthermore, platelets promote the formation of ovarian cancer spheres that express MIC markers and the metastatic protein TF. Our results suggest that platelet-cancer cell interaction plays a role in the formation of metastatic foci.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1304-z) contains supplementary material, which is available to authorized users.

Anti-tumor activity of a polysaccharide from blueberry

Blueberries (Vaccinium spp.) are rich in bioactive compounds. However, the biological activity of polysaccharides from blueberry has not been reported so far. This study evaluated the anti-tumor and immunological activities of a polysaccharide (BBP3-1) from blueberry in S180-bearing mice. The experimental results indicated that BBP3-1 (100 mg·kg⁻¹·d⁻¹) inhibited the tumor growth rate by 73.4%. Moreover, this group, compared with the model control, had shown an effect of increasing both the spleen and thymus indices (p < 0.05), increasing phagocytosis by macrophages (p < 0.05), boosting the proliferation and transformation of lymphocytes (p < 0.01), promoting the secretion of TNF-α, IFN-γ, and IL-2 (p < 0.05) and improving NK cell activity (p < 0.01). From this study, we could easily conclude that BBP3-1 has the ability to inhibit tumor progression and could act as a good immunomodulator.

Hypercoagulation in colorectal cancer: what can platelet indices tell us?

Colorectal cancer, as all solid malignancies, is accompanied by changes in the haemostatic mechanism favoring the establishment of a thrombotic potential, with platelets playing a key-role in this framework; they further link colorectal cancer progression and hypercoagulation with the immune-response against the neoplastic spread. Under this rationale, various studies have assessed the use of platelet indices as prognostic markers of the biological behavior of colorectal cancer, demonstrating significant results. We herein attempt to summarize in a narrative and critical approach the relevant available data and the underlying pathophysiology, stressing the necessity of a more thorough understanding and future implementation of platelet indices in all stages of care we deliver to colorectal cancer patients.

Clinical significance of thrombocytosis before preoperative chemoradiotherapy in rectal cancer: predicting pathologic tumor response and oncologic outcome

BACKGROUND

Thrombocytosis is considered an adverse prognostic factor in various malignancies. However, the clinical significance of thrombocytosis in rectal cancer patients is unknown. We investigated the predictive value of thrombocytosis for pathologic tumor response to preoperative chemoradiotherapy (CRT) and oncologic outcomes in patients with rectal cancer.

METHODS

A total of 314 patients who underwent preoperative CRT and subsequent rectal resection for rectal cancer were retrospectively evaluated at two tertiary institutions. Univariate and multivariate analyses of the clinical parameters were performed to identify markers predictive of a pathologic complete response (pCR). The Kaplan-Meier method was used to estimate 3-year disease-free and overall survival rates.

RESULTS

Sixty-nine patients (22 %) had thrombocytosis before CRT, which significantly correlated with a large tumor size and advanced tumor depth. Thirty-nine patients (12.4 %) achieved a pCR. In the multivariate analyses, a platelet count of <370,000/μl (odds ratio 5.483; 95 % confidence interval, 1.271-23.653; P = 0.023) and a carcinoembryonic antigen (CEA) level of <5 ng/dl (odds ratio, 3.084; 95 % confidence interval, 1.291-7.368; P = 0.011) were identified as independent predictive factors for a pCR. Patients with pretreatment thrombocytosis had lower 3-year disease-free (P = 0.037) and overall survival (P = 0.001) rates than patients with normal pretreatment platelet counts.

CONCLUSIONS

Thrombocytosis is a negative predictive factor for a pCR and has an adverse impact on survival in rectal cancer. The predictive value of this easily available clinical factor should not be underestimated, and better therapeutic strategies for these tumors are required.

Living in shear: platelets protect cancer cells from shear induced damage

Pharmacologically and genetically induced thrombocytopenia is associated with decreased metastasis, highlighting the importance of platelets in the bloodborne dissemination of cancer cells. It is frequently suggested that platelets support metastasis, in part, by protecting cancer cells from shear stress, a biomechanical force generated by blood flow. However, there is currently no evidence to support this hypothesis. To address this, we investigated the effect of shear stress on A2780 ovarian cancer cells in the presence and absence of platelets. Using a cone and plate viscometer, suspensions of A2780 cells with and without platelets were exposed to shear rates representing venous (200 s(-1)) and arterial (1,500 s(-1)) blood flow. Lactate dehydrogenase (LDH) release was used to quantify shear induced membrane damage. Both venous and arterial shear rates induced the release of LDH from A2780 cells, demonstrating their susceptibility to shear forces. In contrast, platelets released minimal levels of LDH in response to similar conditions. In the presence of platelets, there was a significant decrease in LDH release by A2780 cells under shear conditions, suggesting that platelets can confer protection against shear induced damage. The disruption of platelet-cancer cell interactions could increase the shear stress induced destruction of cancer cells in vivo.

Preoperative platelet count in esophageal squamous cell carcinoma: is it a prognostic factor?

PURPOSE

Platelet count is inversely related to prognosis in many cancers; however, its role in esophageal cancer is still controversial. The purpose of this study was to determine the prognostic value of preoperative platelet count in esophageal squamous cell carcinoma (ESCC).

METHODS

From January 2006 to December 2008, a retrospective analysis of 425 consecutive patients with ESCC was conducted. A receiver operating characteristic (ROC) curve for survival prediction was plotted to verify the optimum cutoff point for preoperative platelet count. Univariate and multivariate analyses were performed to evaluate the prognostic parameters.

RESULTS

A ROC curve for survival prediction was plotted to verify the optimum cutoff point for platelet count, which was 205 (× 10(9)/L). Patients with platelet count ≤ 205 had a significantly better 5-year survival than patients with a platelet count >205 (60.7 vs. 31.6 %, P < 0.001). The 5-year survival of patients either with platelet count ≤ 205 or >205 were similar (68.6 vs. 58.8 %, P = 0.085) when the nodes were negative. However, the 5-year survival of patients with platelet count ≤ 205 was better than that of patients with a platelet count >205 when the nodes were involved (32.0 vs. 12.7 %, P = 0.004). Multivariate analysis showed that platelet count (P = 0.013), T grade (P = 0.017), and N staging (P < 0.001) were independent prognostic factors.

CONCLUSIONS

Preoperative platelet count is a predictive factor for long-term survival in ESCC, especially in nodal-positive patients. We conclude that 205 (×10(9)/L) may be the optimum cutoff point for platelet count in predicting survival in ESCC patients.

Platelet count predicts prognosis in operable non-small cell lung cancer

Platelets play a significant role in cancer cell growth, progression and metastasis. However, in non-small cell lung cancer (NSCLC), the association between a patient's platelet count and prognosis has not previously been fully elucidated. The aim of the present study was to investigate the correlation between platelet count, patients' characteristics and prognosis in patients with NSCLC. A total of 510 NSCLC patients were enrolled in the present study. The median platelet count in the NSCLC patients was 203×10⁹/l (95% CI, 115-358×10⁹/l). The median platelet count in T3 and T4 patients was significantly higher than that of T1 and T2 patients (median, 263×10⁹/l and 253.5×10⁹/l vs. 199.5×10⁹/l and 196.5×10⁹/l, respectively; P<0.001). The 3-year cumulative overall survival (OS) probability was 75.3% for patients with normal platelet counts and 59.2% for patients with elevated platelet counts. When compared with the patients with normal platelet counts, the patients with elevated platelet counts had an increased risk of disease progression (HR, 1.568; 95% CI, 1.015-2.453). Pre-operative platelet counts are a novel independent prognostic biomarker in operable NSCLC.

Hemostatic factors, innate immunity and malignancy

Genetics-based studies have established the critical importance of tumor cell-associated tissue factor, circulating and endothelial cell-associated regulators of thrombin function and multiple thrombin substrates in metastasis. There appear to be multiple pathways by which procoagulants influence tumor biology, but the capacity of hemostatic factors to regulate innate immune function is at least one emerging theme. Several reports have shown that the platelet/fibrin(ogen) axis supports metastasis by limiting natural killer cellmediated lysis of newly-localized micrometastases. Furthermore, there is increasingly compelling evidence that hemostatic and innate immune system interactions also support very early events in cancer development. Analyses of the role of fibrin(ogen) in inflammation-driven colon cancer established a major role for this provisional matrix protein in early tumor development. A seminal property of fibrin(ogen) driving tumor formation in this context is the capacity to support local leukocyte activation events through engagement of the leukocyte integrin α(M)β(2). More recent studies have also suggested that hemostatic factors can, in at least some settings, program the malignant phenotype in tumor cells. Platelet-derived TGF-β1 and other platelet products were reported to trigger a more invasive and prometastatic epithelial-mesenchymal-like transition in embolic tumor cells. These findings support the intriguing concept that tumor cell functional properties can continue to evolve, even beyond the primary tumor site, in response to tumor cell-hemostatic factor interactions in the bloodstream. Taken together, there is strong evidence that the hemostatic system plays a multifaceted role in cancer pathogenesis and that therapies targeting selected hemostatic factors may present a powerful means to impede tumor development and metastasis.

Tumor-platelet interaction in solid tumors

Elevated platelet counts in patients diagnosed with malignant tumors were first described more than 100 years ago. Today it is well known that in many types of solid tumors, thrombocytosis at the time of diagnosis is associated with shorter survival. From this well-documented clinical correlation between platelet count and prognosis of solid tumors, the following questions arise: (i) Are the increased platelet counts the reason for shortened survival as platelet-secreted cytokines might boost tumor growth and angiogenesis? (ii) Do platelets affect tumor metastasis thereby shortening survival time? or (iii) Are increased platelet counts simply an epiphenomenon of tumor growth with larger tumors resulting in higher platelet counts and shorter survival times? We address these three questions within our review of the current literature to provide a comprehensive overview of the current concepts in tumor-platelet interaction.