Endothelial progenitor cells and circulating endothelial cells in early prostate cancer: a comparison with plasma vascular markers

Plasma von Willebrand factor levels in patients with cancer: A meta‑analysis

von Willebrand Factor (VWF) is well recognized for being dysregulated in various malignancies and has emerged as a potential biomarker for cancer detection. The present meta-analysis aimed to elucidate the association between plasma VWF and the incidence and metastasis of cancer. For this purpose, a comprehensive search was conducted across multiple databases from their inception until March 3, 2023. This culminated in the selection of 15 original studies on various types of cancer, including a collective sample of 1,403 individuals. The standardized mean difference (SMD) and 95% confidence intervals (CIs) were employed as statistical parameters to determine the association between plasma VWF and the incidence and metastasis of cancer. These were estimated using a random-effects model. The pooled data revealed that the plasma VWF levels of patients with cancer were significantly elevated compared with those of healthy controls (SMD, 0.98; 95% CI, 0.59-1.36), and a significant association was observed between plasma VWF levels and cancer metastasis (SMD, 0.69; 95% CI, 0.33-1.06). The symmetry of the Begg's funnel plots indicated that no significant bias was present in the analyses of VWF in cancer and its metastasis. In summary, the results of the present meta-analysis support the hypothesis that increased plasma VWF levels may serve as a biomarker for cancer and metastatic progression.

Proteome profiling of ductal carcinoma in situ

BACKGROUND AND AIM

DCIS is the most common type of non-invasive breast cancer, accounting for about 15 to 30%. Proteome profile is used to detect biomarkers in the tissues of breast cancer patients by mass spectrometry. This study aimed to obtain the expression profile of DCIS proteome, and the expression profile of invasive biomarkers, and finally to introduce a dedicated biomarker panel to facilitate the prognosis and early detection for in situ breast cancer patients.

METHODS AND MATERIALS

In this study, 10 patients with breast cancer (DCIS) were studied. Benign (marginal) and cancerous tissue samples were obtained from patients for proteomics experiments. Initially, all tissue proteins were extracted using standard methods, and the proteins were separated using two-dimensional electrophoresis. Then, the expression amount of the extracted proteins was determined by ITRAQ. The data were analysed by R software, and gene ontology was utilised for describing the protein in detail.

RESULTS

30 spots on gel electrophoresis were found in the tumor tissue group (sample), and 15 spots in the margin group (control) with P < 0.05. Healthy and cancerous tissue gels showed that 5 spots had different expression. VWF, MMP9, ITGAM, MPO and PLG protein spots were identified using the site www.ebi.ac.uk/IPI. Finally, protein biomarkers for breast tumor tissue with margin were introduced with the names of P04406, P49915, P05323, P06733, and P02768.

DISCUSSION

There are 5 critical proteins in inducing cancer pathways especially complement and coagulation cascades. The hall markers of a healthy cell to be cancerous are proliferation, invasion, angiogenesis, and changes in the immune system. Hence, regulation of protein plays a key role in developing recurrence to breast cancer in margins.

The role of von Willebrand factor in breast cancer metastasis

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VWF plays an important role in breast tumour progression and metastasis.

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Patients with metastatic breast cancer have significantly elevated plasma VWF.

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Increased levels of highly adhesive VWF may regulate platelet-tumour interactions.

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VWF may protect disseminated tumour cells from chemotherapy.

Breast cancer is the most common female cancer globally, with approximately 12% of patients eventually developing metastatic disease. Critically, limited effective treatment options exist for metastatic breast cancer. Recently, von Willebrand factor (VWF), a haemostatic plasma glycoprotein, has been shown to play an important role in tumour progression and metastasis. In breast cancer, a significant rise in the plasma levels of VWF has been reported in patients with malignant disease compared to benign conditions and healthy controls, with an even greater increase seen in patients with disseminated disease. Direct interactions between VWF, tumour cells, platelets and endothelial cells may promote haematogenous dissemination and thus the formation of metastatic foci. Intriguingly, patients with metastatic disease have unusually large VWF multimers. This observation has been proposed to be a result of a dysfunctional or deficiency of VWF-cleaving protease activity, ADAMTS-13 activity, which may then regulate the platelet-tumour adhesive interactions in the metastatic process. In this review, we provide an overview of VWF in orchestrating the pathological process of breast cancer dissemination, and provide supporting evidence of the role of VWF in mediating metastatic breast cancer.

Von Willebrand factor and cancer; metastasis and coagulopathies

Von Willebrand factor (VWF) is a multimeric procoagulant plasma glycoprotein that mediates platelet adhesion along the endothelium. In addition to its role maintaining normal hemostasis, more recently novel biological functions for VWF have been described, including inflammation, angiogenesis, and metastasis. Significantly increased plasma VWF levels have been reported across a variety of cancer patient cohorts. Given that VWF is established as a risk factor for venous thrombosis, this is of direct clinical importance. Moreover, elevated VWF has also been observed localized within the tumor microenvironment, correlating with advanced disease stage and poorer clinical outcome. Critically, evidence suggests that elevated VWF levels in cancer patients may not only contribute to cancer associated coagulopathies but may also mediate cancer progression and metastasis. Studies have shown that VWF can promote pro-inflammatory signaling, regulate angiogenesis and vascular permeability, which may facilitate tumor cell growth and extravasation across the vessel wall. Endothelial secreted VWF multimers contribute to the adhesion and transendothelial migration of tumor cells key for tumor dissemination. In support of this, VWF inhibition attenuated metastasis in vivo. Perhaps most intriguingly, specific tumor cells have been reported to acquire de novo VWF expression which increases tumor-platelet heteroaggregates and confers enhanced metastatic activity. Current knowledge on the roles of VWF in cancer and in particular its contribution to metastasis and cancer associated coagulopathies is summarized in this review.

Long-lasting prothrombotic state implied by changes of plasma von Willebrand factor parameters after radical prostatectomy for prostate malignancy

OBJECTIVES

Thromboembolic complications are present in 0.8%-16.8% of the cases after radical prostatectomy (RP). Association between elevated plasma von Willebrand factor (VWF) levels-as an endothelial activation marker-and increased risk of thrombotic events has been evidenced. We aimed to elicit new data on the VWF after RP in prostate cancer patients and explore the role of it as a thrombotic risk factor. Upon perioperative plasma VWF levels (VWF:Ag) its collagen-binding (CB) activity (VWF:CB), multimerization, and cleaving enzyme (ADAMTS13 [a disintegrin and metalloprotease with thrombospondin type repeats, motif 1, type 13]) of the VWF multimers were quantitated along with Factor VIII and routine laboratory parameters in this observational pilot study.

METHODS

Plasma samples of 24 prostate cancer patients were collected before (-1 day; D-1) and after RP (1 hour, 6 days, 1 month, and 10 months; H1, D6, M1, and M10). VWF:Ag, VWF:CB, ADAMTS13:Ag were measured by ELISA, and the multimer distribution by electrophoresis and quantitative densitometry. Factor VIII, fibrinogen, D-dimer, and other routine laboratory parameters were determined as well. Preoperative values served as baselines which were compared to controls (24 healthy individuals).

RESULTS

VWF:Ag and CB elevated by 122% and 143% respectively at H1 after RP then plateaued at D6 compared to baseline values. ADAMTS13/VWF:Ag ratio reduced by 41% at H1, and by 46% at D6, meanwhile the ratio of high molecular weight multimers increased as well. Values returned to baseline at M1 and further reduced to the levels of the controls at M10. All of the 24 patients at H1 and D6 and 14 at M10 were in potential prothombotic state according ROC analysis of the VWF parameters as indicators.

CONCLUSIONS

Prostate malignancy and then surgical stress, and inflammatory reactions induced release of VWF from the endothelial cells, along with an increasing amount of large multimers and relative reduction of ADAMTS13 level. Because these changes mark a prothrombotic state even at M1 after RP, more than 1 month follow-up and prophylactic targeting through the thrombotic and inflammatory activity of the VWF is proposed. Evaluation of VWF parameters provides new information about the long-term disturbances of primary hemostasis after radical pelvic oncologic surgery like RP and might improve the understanding the physiological and pathological recovery.

The role of ADAMTS-13 and von Willebrand factor in cancer patients: Results from the Vienna Cancer and Thrombosis Study

BACKGROUND

Cancer-associated venous thromboembolism (VTE) is an important complication in the course of a malignant disease. Low ADAMTS-13 (a disintegrin-like and metalloproteinase with thrombospondin type 1 motif 13) and increased von Willebrand Factor (VWF) levels in cancer patients have been described numerously.

OBJECTIVES

Investigation of the influence of ADAMTS-13 and VWF on the probability of VTE and survival in malignancy.

PATIENTS/METHODS

In the framework of the ongoing prospective Cancer and Thrombosis Study (CATS) ADAMTS-13 activity and VWF antigen levels were investigated in cancer patients.

RESULTS

In total, 795 patients with various tumor types (364 female/431 male, median age 62 years) were included; of those, 56 developed VTE and 359 patients died during a median follow-up time of 730 days. The hazard ratio (HR) of VTE per doubling of VWF level was 1.56 (95% confidence interval [CI] 1.13-2.16) in multivariable competing risk analysis. ADAMTS-13 levels showed no correlation with the incidence of VTE in univariate competing risk analysis. The HR of mortality per doubling of VWF level was 1.46 (95% CI 1.28-1.66) and per SD increment of ADAMTS-13was 0.90 (95% CI 0.81-1.00) in multivariable Cox regression analysis. Patients with VWF >75th percentile and concomitant low (<25th percentile) or medium (25-75th percentile) ADAMTS-13 values had the highest probability of mortality (HR 4.31 and 4.75, respectively).

CONCLUSIONS

High VWF levels were significantly associated with the risk of developing VTE in cancer patients, whereas ADAMTS-13 was not. Low ADAMTS-13 and increased VWF levels were independently associated with worse overall survival.

Flow cytometric analysis of circulating endothelial cells and endothelial progenitors for clinical purposes in oncology: A critical evaluation

Malignant tumors are characterized by uncontrolled cell growth and metastatic spread, with a pivotal importance of the phenomenon of angiogenesis. For this reason, research has focused on the development of agents targeting the vascular component of the tumor microenvironment and regulating the angiogenic switch. As a result, the therapeutic inhibition of angiogenesis has become an important component of anticancer treatment, however, its utility is partly limited by the lack of an established methodology to assess its efficacy in vivo. Circulating endothelial cells (CECs), which are rare in healthy subjects and significantly increased in different tumor types, represent a promising tool for monitoring the tumor clinical outcome and the treatment response. A cell population circulating into the blood also able to form endothelial colonies in vitro and to promote vasculogenesis is represented by endothelial progenitor cells (EPCs). The number of both of these cell types is extremely low and they cannot be identified using a single marker, therefore, in absence of a definite consensus on their phenotype, require discrimination using combinations of antigens. Multiparameter flow cytometry (FCM) is ideal for rapid processing of high numbers of cells per second and is commonly utilized to quantify CECs and EPCs, however, remains technically challenging since there is as yet no standardized protocol for the identification and enumeration of these rare events. Methodology in studies on CECs and/or EPCs as clinical biomarkers in oncology is heterogeneous and data have been obtained from different studies leading to conflicting conclusions. The present review presented a critical review of the issues that limit the comparability of results of the most significant studies employing FCM for CEC and/or EPC detection in patients with cancer.

Increased pre-surgical numbers of endothelial progenitor cells and circulating endothelial cells in colorectal cancer fail to predict outcome

INTRODUCTION

The endothelium and angiogenesis are therapeutic targets in cancer. Response to treatment may be assessed by laboratory plasma markers such as circulating endothelial cells (CECs), endothelial progenitor cells (EPCs), von Willebrand factor (vWf), soluble E selectin, vascular endothelial growth factor (VEGF) and angiogenin. We hypothesised that these markers, obtained before surgery, would predict 2-year outcome after surgery with or without anti-angiogenic therapy for colorectal cancer (CRC).

METHODS

We recruited 154 patients with CRC, of whom 51 were treated with surgery alone, 74 were treated with standard chemotherapy (5-fluorouracil) and 29 were treated with standard chemotherapy plus anti-VEGF therapy (Avastin). Peripheral blood was taken before surgery. CD34(+)/CD45(-)/CD146(+) CECs and CD34(+)/CD45(-)/CD309 [KDR](+) EPCs were measured by flow cytometry and plasma markers by ELISA.

RESULTS

After a mean of 2.1 years follow-up (range 1.9-2.3 years), 52 of the patients (33.7 %) experienced a poor outcome (radiological and/or histological evidence of tumour spread or recurrence, or death [n = 26]). In univariate analysis, poor outcome was linked to Dukes' stage (p < 0.001), American Joint Committee on Cancer (AJCC) stage (p < 0.001), type of treatment (surgery alone, standard chemotherapy with or without anti-antigenic therapy) (p = 0.047), CECs (p < 0.02) and EPCs (p < 0.01). In subsequent binary logistic regression analysis, only Dukes' stage (hazard ratio 2.3, 95 % confidence interval 1.0-5.3, p = 0.047) and modified AJCC stage (4.62, 1.88-11.33, p < 0.001) predicted a poor outcome.

CONCLUSION

Endothelial cell markers (CECs, EPCs, vWf, soluble E selectin) and growth factors (VEGF and angiogenin), measured before surgery, have nothing extra to offer in predicting 2-year outcome in colorectal cancer when compared to Dukes' or AJCC stage.

Circulating endothelial progenitor cell: a promising biomarker in clinical oncology

Human cancers are endowed with sustained vascularization capability, and their growth, invasion, and metastasis are vascularization dependent. Recently, accumulated body of evidence suggests that endothelial progenitor cells (EPCs) can support vasculogenesis and induce angiogenesis through paracrine mechanisms. In addition, numerous clinical studies have revealed the increase in the number of EPCs in the peripheral blood of cancer patients and demonstrated the correlation of circulating EPCs (CEPCs) with the clinical outcomes. This review highlights current enrichment procedures and methods for the detection of CEPCs and different biomarkers to identify CEPCs as well as the functions of EPCs in tumor vascularization. Furthermore, we systematically review available studies on the clinical relevance of CEPCs in cancer patients to explore the potential diagnostic and prognostic values of CEPCs. Although several contrasting results exist, CEPCs can conceivably serve as a promising biomarker for the early diagnosis, prognosis prediction, and treatment response indication in the future. Additionally, further well-designed clinical studies with larger sample size and unique, specific enumeration procedures are warranted to achieve further insight into the clinical implications of CEPCs.

Effect of standard chemotherapy and antiangiogenic therapy on plasma markers and endothelial cells in colorectal cancer

Introduction:

The importance of the endothelium in angiogenesis and cancer is undisputed, and its integrity may be assessed by laboratory markers such as circulating endothelial cells (CECs), endothelial progenitor cells (EPCs), plasma von Willebrand factor (vWf), soluble E selectin, vascular endothelial growth factor (VEGF) and angiogenin. Antiantigenic therapy may be added to standard cytotoxic chemotherapy as a new treatment modality. We hypothesised that additional antiangiogenic therapy acts in a contrasting manner to that of standard chemotherapy on the laboratory markers.

Methods:

We recruited 68 patients with CRC, of whom 16 were treated with surgery alone, 32 were treated with surgery followed by standard chemotherapy (5-flurouracil), and 20 were treated with surgery followed by standard chemotherapy plus anti-VEGF therapy (Avastin). Peripheral blood was taken before surgery, and again 3 months and 6 months later. CD34⁺/CD45⁻/CD146⁺ CECs and CD34⁺/CD45⁻/CD309[KDR]⁺ EPCs were measured by flow cytometry, plasma markers by ELISA.

Results:

In each of the three groups, CECs and EPCs fell at 3 months but were back at pre-surgery levels at 6 months (P<0.05). VEGF was lower in both 3-and 6-month samples in the surgery-only and surgery plus standard chemotherapy groups (P<0.05), but in those on surgery followed by standard chemotherapy plus anti-VEGF therapy, low levels at 3 months (P<0.01) increased to pre-surgery levels at 6 months. In those having surgery and standard chemotherapy, soluble E selectin was lower, whereas angiogenin was higher at 6 months than at baseline (both P<0.05).

Conclusions:

We found disturbances in endotheliod cells regardless of treatment, whereas VEGF returned to levels before surgery in those on antiangiogenic therapy. These observations may have clinical and pathophysiological implications.

Circulating endothelial progenitor cells in castration resistant prostate cancer: a randomized, controlled, biomarker study

Background

Endothelial progenitor cells (CEPs) and circulating endothelial cells (CECs) are potential biomarkers of response to anti-angiogenic treatment regimens. In the current study, we investigated the effect of docetaxel and sunitinib on CEP/CEC kinetics and clinical response in castration resistant prostate cancer (CRPC) patients.

Patients and methods

Chemonaive patients with CRPC were enrolled in this study to receive either sunitinib (37.5 mg/d), in combination with docetaxel (75 mg/m²) or docetaxel alone. CEP and CEC kinetics were analyzed for every cycle. The primary objective was to compare CEP/CEC pharmacodynamics between both treatment arms. We also investigated if CEC/CEP spikes, induced by MTD docetaxel, are suppressed by sunitinib in patients treated with docetaxel/sunitinib relative to docetaxel monotherapy.

Results

A total of 27 patients were enrolled. We observed a significant increase of CEP/CEC (total/viable) counts over time within each cycle (coefficients 0.29233, 0.22092 and 0.26089, respectively; p<0.001). However, no differences between the treatment groups, in terms of CEP and CEC kinetics, were detected. In the docetaxel monotherapy arm 4 (30%) patients responded to therapy with a 50% PSA decline, while 9 (64%) patients showed a PSA decline in the combination group (n.s.). The median PFS in the docetaxel monotherapy group was 3.1 months (2.6–3.6 months, 95% CI) and 6.2 months (4.9–7.4 months, 95% CI; p = 0.062) in the combination arm. Sunitinib/docetaxel was reasonably well tolerated and toxicity manageable.

Conclusion

In summary, no significant differences in CEC and CEP kinetics between the treatment arms were observed, although a highly significant increase of CEPs/CECs within each cycle over time was detected. These results mirror the challenge we have to face when employing anti-angiogenic strategies in CRPC. Additional preclinical research is needed to elucidate the underlying molecular mechanisms. However, docetaxel/sunitinib therapy resulted in a better response in terms of PSA decline and a trend towards improved PFS.

Trial Registery

clinicaltrialsregister.eu EudraCT 2007-003705-27

Fluid phase biopsy for detection and characterization of circulating endothelial cells in myocardial infarction

Elevated levels of circulating endothelial cells (CECs) occur in response to various pathological conditions including myocardial infarction (MI). Here, we adapted a fluid phase biopsy technology platform that successfully detects circulating tumor cells in the blood of cancer patients (HD-CTC assay), to create a high-definition circulating endothelial cell (HD-CEC) assay for the detection and characterization of CECs. Peripheral blood samples were collected from 79 MI patients, 25 healthy controls and six patients undergoing vascular surgery (VS). CECs were defined by positive staining for DAPI, CD146 and von Willebrand Factor and negative staining for CD45. In addition, CECs exhibited distinct morphological features that enable differentiation from surrounding white blood cells. CECs were found both as individual cells and as aggregates. CEC numbers were higher in MI patients compared with healthy controls. VS patients had lower CEC counts when compared with MI patients but were not different from healthy controls. Both HD-CEC and CellSearch® assays could discriminate MI patients from healthy controls with comparable accuracy but the HD-CEC assay exhibited higher specificity while maintaining high sensitivity. Our HD-CEC assay may be used as a robust diagnostic biomarker in MI patients.

Tumor vascularity in prostate cancer: an update on circulating endothelial cells and platelets as noninvasive biomarkers

In order to individually tailor prostate cancer (PCa) treatment, clinicians need better tools to predict prognosis and treatment response. Given the relationship between angiogenesis and cancer progression, circulating endothelial cells (CECs) and their progenitors have logically been proposed as potential biomarkers. The utility of their baseline levels and kinetics has been investigated for years. However, owing to a lack of standardization and validation of CEC and circulating endothelial progenitors enumeration protocols, results have been inconsistent in prostate and other cancers. Similarly, platelets play a significant part in cancer progression, yet the role of platelet-related biomarkers in PCa is unclear. While there have been a number of theoretically interesting platelet-related markers proposed, limited research has been conducted in PCa patients. Currently, CECs and platelets do not have a clear role as biomarkers in routine PCa care. Given the theoretical merits of these cells, prospective trials are warranted.

Angiogenin outperforms VEGF, EPCs and CECs in predicting Dukes' and AJCC stage in colorectal cancer

BACKGROUND

Circulating endothelial cells (CECs), endothelial progenitor cells (EPCs), Willebrand factor (vWf), soluble E-selectin, vascular endothelial growth factor (VEGF) and angiogenin are of interest in cancer vascular biology. However, few studies have looked at more than one in combination. We set out to determine which would be best in predicting the Dukes' and American Joint Committee on Cancer (AJCC) scores in colorectal cancer patients.

METHODS

We recruited 154 patients with colorectal cancer, 29 healthy controls and 26 patients with benign bowel disease. CD34(+) /CD45(-) /CD146(+) CECs and CD34(+) /CD45(-) /CD309[KDR](+) EPCs were measured by flow cytometry, plasma markers by ELISA.

RESULTS

All research indices were raised in colorectal cancer (P < 0·05) compared to control groups. Although CECs (P < 0·05), EPCs (P < 0·01) and angiogenin (P < 0·01) increased stepwise across the four Dukes' stages and four AJCC stages, only angiogenin remained significant in multiple regression analysis (P = 0·003 for Dukes, P = 0·01 for AJCC). Angiogenin levels were higher in Dukes' stages C and D compared to stage A, and AJCC stages 4-6 and 7-10 compared to stage 1 (all P < 0·05). Adding a second research marker to angiogenin did not markedly improve this relationship.

CONCLUSION

Although we found disturbances in endotheliod cells and plasma markers of the endothelium and growth factors, only angiogenin levels were independently associated with progression of the Dukes' stage and AJCC stage, with the association with Duke's stage being stronger. We suggest that angiogenin is a potential biomarker in risk stratification for colorectal cancer, and may aid clinical decision making.

Fatty acid synthase is a key target in multiple essential tumor functions of prostate cancer: uptake of radiolabeled acetate as a predictor of the targeted therapy outcome

Fatty acid synthase (FASN) expression is elevated in several cancers, and this over-expression is associated with poor prognosis. Inhibitors of FASN, such as orlistat, reportedly show antitumor effects against cancers that over-express FASN, making FASN a promising therapeutic target. However, large variations in FASN expression levels in individual tumors have been observed, and methods to predict FASN-targeted therapy outcome before treatment are required to avoid unnecessary treatment. In addition, how FASN inhibition affects tumor progression remains unclear. Here, we showed the method to predict FASN-targeted therapy outcome using radiolabeled acetate uptake and presented mechanisms of FASN inhibition with human prostate cancer cell lines, to provide the treatment strategy of FASN-targeted therapy. We revealed that tumor uptake of radiolabeled acetate reflected the FASN expression levels and sensitivity to FASN-targeted therapy with orlistat in vitro and in vivo. FASN-targeted therapy was noticeably effective against tumors with high FASN expression, which was indicated by high acetate uptake. To examine mechanisms, we established FASN knockdown prostate cancer cells by transduction of short-hairpin RNA against FASN and investigated the characteristics by analyses on morphology and cell behavior and microarray-based gene expression profiling. FASN inhibition not only suppressed cell proliferation but prevented pseudopodia formation and suppressed cell adhesion, migration, and invasion. FASN inhibition also suppressed genes involved in production of intracellular second messenger arachidonic acid and androgen hormones, both of which promote tumor progression. Collectively, our data demonstrated that uptake of radiolabeled acetate is a useful predictor of FASN-targeted therapy outcome. This suggests that [1-(11)C]acetate positron emission tomography (PET) could be a powerful tool to accomplish personalized FASN-targeted therapy by non-invasive visualization of tumor acetate uptake and selection of responsive tumors. FASN-targeted therapy could be an effective treatment to suppress multiple steps related to tumor progression in prostate cancers selected by [1-(11)C]acetate PET.

Circulating endothelial progenitor cells in gynaecological cancer

Objectives

To compare the frequency and absolute numbers of circulating endothelial progenitor cells (EPCs) in healthy control subjects and patients with gynaecological cancer, and to test the hypothesis that cancer treatment lowers EPC numbers.

Methods

Patients with cervical or ovarian cancer and healthy control subjects provided peripheral blood samples for the isolation of mononuclear cells. EPCs were identified by quadruple immunofluorescence staining and flow cytometry as CD45–/CD34+/CD133+/vascular endothelial growth factor receptor 2 (VEGFR2)+ cells.

Results

In total, 28 participants were enrolled. Circulating EPCs were present at higher frequencies (and in greater absolute numbers) in patients with cervical or ovarian cancer ( n = 14) than in controls ( n = 14). Concurrent chemoradiation therapy or surgery significantly reduced the frequency and number of EPCs in patients with gynaecological cancer, compared with pretreatment levels.

Conclusions

EPC levels decline throughout cancer treatment; their measurement may therefore be a useful surrogate marker to monitor treatment response.

The PCa Tumor Microenvironment

The tumor microenvironment (TME) is a very complex niche that consists of multiple cell types, supportive matrix and soluble factors. Cells in the TME consist of both host cells that are present at tumor site at the onset of tumor growth and cells that are recruited in either response to tumor- or host-derived factors. PCa (PCa) thrives on crosstalk between tumor cells and the TME. Crosstalk results in an orchestrated evolution of both the tumor and microenvironment as the tumor progresses. The TME reacts to PCa-produced soluble factors as well as direct interaction with PCa cells. In return, the TME produces soluble factors, structural support and direct contact interactions that influence the establishment and progression of PCa. In this review, we focus on the host side of the equation to provide a foundation for understanding how different aspects of the TME contribute to PCa progression. We discuss immune effector cells, specialized niches, such as the vascular and bone marrow, and several key protein factors that mediate host effects on PCa. This discussion highlights the concept that the TME offers a potentially very fertile target for PCa therapy.