Alternative vascularization mechanisms in cancer: Pathology and therapeutic implications

Gibbs point field model quantifies disorder in microvasculature of U87-glioblastoma

Microvascular proliferation in glioblastoma multiforme is a biological key mechanism to facilitate tumor growth and infiltration and a main target for treatment interventions. The vascular architecture can be obtained by Single Plane Illumination Microscopy (SPIM) to evaluate vascular heterogeneity in tumorous tissue. We make use of the Gibbs point field model to quantify the order of regularity in capillary distributions found in the U87 glioblastoma model in a murine model and to compare tumorous and healthy brain tissue. A single model parameter Γ was assigned that is linked to tissue-specific vascular topology through Monte-Carlo simulations. Distributions of the model parameter Γ differ significantly between glioblastoma tissue with mean 〈Γ_G〉=2.1±0.4, as compared to healthy brain tissue with mean 〈Γ_H〉=4.9±0.4, suggesting that the average Γ-value allows for tissue differentiation. These results may be used for diagnostic magnetic resonance imaging, where it has been shown recently that Γ is linked to tissue-inherent relaxation parameters.

Critical considerations for targeting colorectal liver metastases with nanotechnology

Colorectal cancer remains a significant cause of morbidity and mortality worldwide. Half of all patients develop liver metastases, presenting unique challenges for their treatment. The shortcomings of conventional chemotherapy has encouraged the use of nanomedicines; the application of nanotechnology in the diagnosis and treatment of disease. In spite of technological improvements in nanotechnology, the complexity of biological systems hinders the prospect of nanomedicines being applied in cancer therapy at the present time. This review highlights current biological barriers and discusses aspects of tumor biology together with the physicochemical features of the nanocarrier, that need to be considered in order to develop effective nanotherapeutics for colorectal cancer patients with liver metastases. It becomes clear that incorporating an interdisciplinary approach when developing nanomedicines should assure appropriate disease-driven design and that this will form a critical step in improving their clinical translation. This article is characterized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Endothelial Cells in the Tumor Microenvironment

Angiogenesis is a critical process required for tumor progression. Newly formed blood vessels provide nutrition and oxygen to the tumor contributing to its growth and development. However, endothelium also plays other functions that promote tumor metastasis. It is involved in intravasation, which allows invasive cancer cells to translocate into the blood vessel lumen. This phenomenon is an important stage for cancer metastasis. Besides direct association with cancer development, endothelial cells are one of the main sources of cancer-associated fibroblasts (CAFs). The heterogeneous group of CAFs is the main inductor of migration and invasion abilities of cancer cells. Therefore, the endothelium is also indirectly responsible for metastasis. Considering the above, the endothelium is one of the important targets of anticancer therapy. In the chapter, we will present mechanisms regulating endothelial function, dependent on cancer and cancer niche cells. We will focus on possibilities of suppressing pro-metastatic endothelial functions, applied in anti-cancer therapies.

The Acidic Tumor Microenvironment as a Driver of Cancer

Acidic metabolic waste products accumulate in the tumor microenvironment because of high metabolic activity and insufficient perfusion. In tumors, the acidity of the interstitial space and the relatively well-maintained intracellular pH influence cancer and stromal cell function, their mutual interplay, and their interactions with the extracellular matrix. Tumor pH is spatially and temporally heterogeneous, and the fitness advantage of cancer cells adapted to extracellular acidity is likely particularly evident when they encounter less acidic tumor regions, for instance, during invasion. Through complex effects on genetic stability, epigenetics, cellular metabolism, proliferation, and survival, the compartmentalized pH microenvironment favors cancer development. Cellular selection exacerbates the malignant phenotype, which is further enhanced by acid-induced cell motility, extracellular matrix degradation, attenuated immune responses, and modified cellular and intercellular signaling. In this review, we discuss how the acidity of the tumor microenvironment influences each stage in cancer development, from dysplasia to full-blown metastatic disease.

Vessel co-option and resistance to anti-angiogenic therapy

Vessel co-option is a non-angiogenic mechanism of tumour vascularisation in which cancer cells utilise pre-existing blood vessels instead of inducing new blood vessel formation. Vessel co-option has been observed across a range of different tumour types, in both primary cancers and metastatic disease. Importantly, vessel co-option is now implicated as a major mechanism that mediates resistance to conventional anti-angiogenic drugs and this may help to explain the limited efficacy of this therapeutic approach in certain clinical settings. This includes the use of anti-angiogenic drugs to treat advanced-stage/metastatic disease, treatment in the adjuvant setting and the treatment of primary disease. In this article, we review the available evidence linking vessel co-option with resistance to anti-angiogenic therapy in numerous tumour types, including breast, colorectal, lung and pancreatic cancer, glioblastoma, melanoma, hepatocellular carcinoma, and renal cell carcinoma. The finding that vessel co-option is a significant mechanism of resistance to anti-angiogenic therapy may have important implications for the future of anti-cancer therapy, including (a) predicting response to anti-angiogenic drugs, (b) the need to develop therapies that target both angiogenesis and vessel co-option in tumours, and (c) predicting the response to other therapeutic modalities, including immunotherapy.

KRAS Mutations Predict Response and Outcome in Advanced Lung Adenocarcinoma Patients Receiving First-Line Bevacizumab and Platinum-Based Chemotherapy

Bevacizumab, combined with platinum-based chemotherapy, has been widely used in the treatment of advanced-stage lung adenocarcinoma (LADC). Although KRAS (V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog) mutation is the most common genetic alteration in human LADC and its role in promoting angiogenesis has been well established, its prognostic and predictive role in the above setting remains unclear. The association between KRAS exon 2 mutational status and clinicopathological variables including progression-free survival and overall survival (PFS and OS, respectively) was retrospectively analyzed in 501 Caucasian stage IIIB-IV LADC patients receiving first-line platinum-based chemotherapy (CHT) with or without bevacizumab (BEV). EGFR (epidermal growth factor receptor)-mutant cases were excluded. Of 247 BEV/CHT and 254 CHT patients, 95 (38.5%) and 75 (29.5%) had mutations in KRAS, respectively. KRAS mutation was associated with smoking (p = 0.008) and female gender (p = 0.002) in the BEV/CHT group. We found no difference in OS between patients with KRAS-mutant versus KRAS wild-type tumors in the CHT-alone group (p = 0.6771). Notably, patients with KRAS-mutant tumors demonstrated significantly shorter PFS (p = 0.0255) and OS (p = 0.0186) in response to BEV/CHT compared to KRAS wild-type patients. KRAS mutation was an independent predictor of shorter PFS (hazard ratio, 0.597; p = 0.011) and OS (hazard ratio, 0.645; p = 0.012) in the BEV/CHT group. G12D KRAS-mutant patients receiving BEV/CHT showed significantly shorter PFS (3.7 months versus 8.27 months in the G12/13x group; p = 0.0032) and OS (7.2 months versus 16.1 months in the G12/13x group; p = 0.0144). In this single-center, retrospective study, KRAS-mutant LADC patients receiving BEV/CHT treatment exhibited inferior PFS and OS compared to those with KRAS wild-type advanced LADC. G12D mutations may define a subset of KRAS-mutant LADC patients unsuitable for antiangiogenic therapy with BEV.

Vasculogenic Mimicry: Become an Endothelial Cell "But Not So Much"

Blood vessels supply all body tissues with nutrients and oxygen, take away waste products and allow the arrival of immune cells and other cells (pericytes, smooth muscle cells) that form part of these vessels around the principal endothelial cells. Vasculogenic mimicry (VM) is a tumor blood supply system that takes place independently of angiogenesis or endothelial cells, and is associated with poor survival in cancer patients. Aberrant expression of VE-cadherin has been strongly associated with VM. Even more, VE-cadherin has constitutively high phosphorylation levels on the residue of Y658 in human malignant melanoma cells. In this review we focus on non-endothelial VE-cadherin and its post-translational modifications as a crucial component in the development of tumor VM, highlighting the signaling pathways that lead to their pseudo-endothelial and stem-like phenotype and the role of tumor microenvironment. We discuss the importance of the tumor microenvironment in VM acquisition, and describe the most recent therapeutic targets that have been proposed for the repression of VM.

Glioblastoma multiforme restructures the topological connectivity of cerebrovascular networks

Glioblastoma multiforme alters healthy tissue vasculature by inducing angiogenesis and vascular remodeling. To fully comprehend the structural and functional properties of the resulting vascular network, it needs to be studied collectively by considering both geometric and topological properties. Utilizing Single Plane Illumination Microscopy (SPIM), the detailed capillary structure in entire healthy and tumor-bearing mouse brains could be resolved in three dimensions. At the scale of the smallest capillaries, the entire vascular systems of bulk U87- and GL261-glioblastoma xenografts, their respective cores, and healthy brain hemispheres were modeled as complex networks and quantified with fundamental topological measures. All individual vessel segments were further quantified geometrically and modular clusters were uncovered and characterized as meta-networks, facilitating an analysis of large-scale connectivity. An inclusive comparison of large tissue sections revealed that geometric properties of individual vessels were altered in glioblastoma in a relatively subtle way, with high intra- and inter-tumor heterogeneity, compared to the impact on the vessel connectivity. A network topology analysis revealed a clear decomposition of large modular structures and hierarchical network organization, while preserving most fundamental topological classifications, in both tumor models with distinct growth patterns. These results augment our understanding of cerebrovascular networks and offer a topological assessment of glioma-induced vascular remodeling. The findings may help understand the emergence of hypoxia and necrosis, and prove valuable for therapeutic interventions such as radiation or antiangiogenic therapy.

Vessel co-option in cancer

All solid tumours require a vascular supply in order to progress. Although the ability to induce angiogenesis (new blood vessel growth) has long been regarded as essential to this purpose, thus far, anti-angiogenic therapies have shown only modest efficacy in patients. Importantly, overshadowed by the literature on tumour angiogenesis is a long-standing, but continually emerging, body of research indicating that tumours can grow instead by hijacking pre-existing blood vessels of the surrounding nonmalignant tissue. This process, termed vessel co-option, is a frequently overlooked mechanism of tumour vascularization that can influence disease progression, metastasis and response to treatment. In this Review, we describe the evidence that tumours located at numerous anatomical sites can exploit vessel co-option. We also discuss the proposed molecular mechanisms involved and the multifaceted implications of vessel co-option for patient outcomes.

Establishment of three-dimensional canine osteosarcoma cell lines showing vasculogenic mimicry and evaluation of biological properties after treatment with 17-AAG

Vasculogenic mimicry (VM) is an alternative type of blood perfusion characterized by formation of non-endothelial cell-lined microcirculatory channels and is responsible for aggressive tumour biology and increased tumour-related mortality. VM-correlated genes are associated with vascular endothelial grown factor receptor 1 (VEGFR1), and hypoxia-related (hypoxia inducible factor 1 α-HIF1α) signalling pathways, whose molecules are client proteins of Hsp90 (heat shock protein 90) and are potential therapeutic targets. This pilot study was aimed to investigate vasculogenic mimicry in a three-dimensional (3D) cell culture system of two aggressive canine osteosarcoma (OSA) cell lines (D22 and D17), and to evaluate the response of these cells to 17-AAG (17-N-allylamino-17-demethoxygeldanamycin) treatment in relation to tubular-like structure formation in vitro. Only D17 cell line formed hollow matrix channels in long-term 3D cultures and assumed endothelial morphology, with cells expressing both Hsp90 and VEGFR1, but lacking expression of endothelial marker CD31. 17-AAG treatment inhibited migration of D17 OSA cells, also decreasing VM markers in vitro and inducing a reduction of HIF1α transcript and protein in this cell line. Taken together, these preliminary data indicate that the biological effects of 17-AAG on D17 3D culture and on HIF1α regulation can provide interesting information to translate these findings from the basic research to clinical approach for the treatment of canine OSA as a model in comparative oncology.

Correlations between quantitative parameters of contrast-enhanced ultrasound and vasculogenic mimicry in murine tumor model: a novel noninvasive technique for assessment?

Objective

Vasculogenic mimicry (VM) is a novel mechanism of tumor blood supply distinct from endothelial vessel (EV). VM is associated with malignancy, invasion, metastasis, and poor prognosis. Hitherto a noninvasive method for the assessment of VM in vivo has been lacking.

Methods

Contrast-enhanced ultrasound (CEUS) was performed to evaluate the quantitative parameters of tumors in mice. CD31 immunohistochemistry-Periodic Acid-Schiff double staining was conducted to identify the VM or EV in tumor tissues. Correlations between perfusion parameters and VM density was analyzed by Pearson correlation test.

Results

By the 15th day after tumor inoculation, the EV and VM density was 31.15 ± 7.14 and 14.11 ± 2.99 per 200× field. The maximal intensity (IMAX) was 301.19 ± 191.56%, and the rise time (RT), time to peak (TTP) and mean transit time (mTT) were 17.38 ± 7.82 s, 20.27 ± 9.61 s and 58.09 ± 26.44 s, respectively. VM density positively correlated to RT (r = 0.3598, P = 0.0226), TTP (r = 0.3733, P = 0.0177) and mTT(r = 0.6483, P <  0.0001), whereas EV density positively correlated to IMAX (r = 0.4519, P = 0.0034). The vascular diameter of VM was substantially larger than that of EV (43.81 ± 5.88 μm vs 11.21 ± 4.13 μm).

Conclusion

Three quantitative parameters related to VM were obtained and the relationships between CEUS and VM were established. CEUS might thus provide a novel noninvasive method to assess VM in vivo.

Significance of Cyclooxygenase-2 in Oncogenesis

The cyclooxygenase-2 (COX-2) enzyme catalyses the first stage of biosynthesis of prostanoids, proteins that are implicated in various physiological and pathological processes in humans and animals. The expression of COX-2 increases significantly during pathological processes accompanied by inflammation, pain and fever. Overexpression of COX-2 was determined in tumour tissues, which suggests that this enzyme participates in oncogenesis. In this paper the topics discussed are mechanisms regulating COX-2 expression, COX isoforms, their role in the body and the oncogenic mechanisms triggered by the overexpression of COX-2, including inhibition of apoptosis, intensification of neoangiogenesis, increased metastatic capacity, and weakening of the immune system. The significance of and the mechanisms by which COX-2 participates in oncogenesis have been studied intensively in recent years. The results are highly promising, and they expand our understanding of the complex processes and changes at the molecular, cellular and tissue level that promote oncogenesis and cancer progression. Notwithstanding the knowledge already gleaned, many processes and mechanisms have not yet been elucidated in human medicine and, in particular, in veterinary medicine. Further research is required to develop effective tumour diagnostic methods and treatment procedures for humans and animals.

Liver Metastases and Histological Growth Patterns: Biological Behavior and Potential Clinical Implications-Another Path to Individualized Medicine?

Colorectal cancer is a major health burden and despite the recent advances in healthcare and screening programs, a great percentage of patients already present metastases once their disease is found. In those cases, liver surgery has an essential role, but even with neoadjuvant chemotherapy there is a high rate of intrahepatic recurrence. New prognostic factors are needed in order to decide the best surgical approach considering the biological behavior of the tumors in order to tailor the used therapies, moving towards individualized medicine/treatment. However, the majority of the factors described in literature are expensive, time consuming, and difficult to apply on a daily basis. Histological growth patterns have emerged over the past few years as a reproducible characteristic, an easy to apply one, and with very low costs since it only needs the standard Haematoxylin and Eosin stained slides of observation. In this article, we provide a review of the histological growth patterns of liver metastases and their prognostic significance, biological meaning, and therapeutic importance.

Neuropilins in the Context of Tumor Vasculature

Neuropilin-1 and Neuropilin-2 form a small family of plasma membrane spanning receptors originally identified by the binding of semaphorin and vascular endothelial growth factor. Having no cytosolic protein kinase domain, they function predominantly as co-receptors of other receptors for various ligands. As such, they critically modulate the signaling of various receptor tyrosine kinases, integrins, and other molecules involved in the regulation of physiological and pathological angiogenic processes. This review highlights the diverse neuropilin ligands and interacting partners on endothelial cells, which are relevant in the context of the tumor vasculature and the tumor microenvironment. In addition to tumor cells, the latter contains cancer-associated fibroblasts, immune cells, and endothelial cells. Based on the prevalent neuropilin-mediated interactions, the suitability of various neuropilin-targeted substances for influencing tumor angiogenesis as a possible building block of a tumor therapy is discussed.

Prognostic value of uPAR expression and angiogenesis in primary and metastatic melanoma

Angiogenesis is important for the progression of cutaneous melanoma. Here, we analyzed the prognostic impact of the angiogenic factor urokinase plasminogen activator resecptor (uPAR), vascular proliferation index (VPI) and tumor necrosis as a measure of hypoxia in a patient series of nodular melanomas (n = 255) and matched loco-regional metastases (n = 78). Expression of uPAR was determined by immunohistochemistry and VPI was assessed by dual immunohistochemistry using Factor-VIII/Ki67 staining. Necrosis was recorded based on HE-slides. As novel findings, high uPAR expression and high VPI were associated with each other, and with increased tumor thickness, presence of tumor necrosis, tumor ulceration, increased mitotic count and reduced cancer specific survival in primary melanoma. In matched cases, VPI was decreased in metastases, whereas the frequency of necrosis was increased. Our findings demonstrate for the first time the impact on melanoma specific survival of uPAR expression and VPI in primary tumors, and of increased necrosis as an indicator of tumor hypoxia in loco-regional metastases. These findings support the importance of tumor angiogenesis in melanoma aggressiveness, and suggest uPAR as an indicator of vascular proliferation and a potential biomarker in melanoma.

Role of Endoglin (CD105) in the Progression of Hepatocellular Carcinoma and Anti-Angiogenic Therapy

The liver is perfused by both arterial and venous blood, with a resulting abnormal microenvironment selecting for more-aggressive malignancies. Hepatocellular carcinoma (HCC) is the most frequent primary liver cancer, the sixth most common cancer globally, and the third leading cause of cancer-related mortality worldwide. HCC is characterized by its hypervascularization. Improving the efficiency of anti-angiogenic treatment and mitigation of anti-angiogenic drug resistance are the top priorities in the development of non-surgical HCC therapies. Endoglin (CD105), a transmembrane glycoprotein, is one of the transforming growth factor β (TGF-β) co-receptors. Involvement of that protein in angiogenesis of solid tumours is well documented. Endoglin is a marker of activated endothelial cells (ECs), and is preferentially expressed in the angiogenic endothelium of solid tumours, including HCC. HCC is associated with changes in CD105-positive ECs within and around the tumour. The large spectrum of endoglin effects in the liver is cell-type- and HCC- stage-specific. High expression of endoglin in non-tumour tissue suggests that this microenvironment might play an especially important role in the progression of HCC. Evaluation of tissue expression, as well as serum concentrations of this glycoprotein in HCC, tends to confirm its role as an important biomarker in HCC diagnosis and prognosis. The role of endoglin in liver fibrosis and HCC progression also makes it an attractive therapeutic target. Despite these facts, the exact molecular mechanisms of endoglin functioning in hepatocarcinogenesis are still poorly understood. This review summarizes the current data concerning the role and signalling pathways of endoglin in hepatocellular carcinoma development and progression, and provides an overview of the strategies available for a specific targeting of CD105 in anti-angiogenic therapy in HCC.

The prognostic impact of consensus molecular subtypes (CMS) and its predictive effects for bevacizumab benefit in metastatic colorectal cancer: molecular analysis of the AGITG MAX clinical trial

BACKGROUND

The consensus molecular subtypes (CMS) is a transcriptome-based classification of colorectal cancer (CRC) initially described in early-stage cohorts, but the associations of CMS with treatment outcomes in the metastatic setting are yet to be established. This study aimed to evaluate the prognostic impact of CMS classification and its predictive effects for bevacizumab benefit in metastatic CRC by correlative analysis of the AGITG MAX trial.

PATIENTS AND METHODS

The MAX trial previously reported improved progression-free survival (PFS) for the addition of bevacizumab (B) to chemotherapy [capecitabine (C)±mitomycin (M)]. Archival primary tumours from 237 patients (50% of trial population) underwent gene expression profiling and classification into CMS groups. CMS groups were correlated to PFS and overall survival (OS). The interaction of CMS with treatment was assessed by proportional hazards model.

RESULTS

The distribution of CMS in MAX were CMS1 18%, CMS2 47%, CMS3 12%, CMS4 23%. CMS1 was the predominant subtype in right-sided primary tumours, while CMS2 was the predominant subtype in left-sided. CMS was prognostic of OS (P = 0.008), with CMS2 associated with the best outcome and CMS1 the worst. CMS remained an independent prognostic factor in a multivariate analysis. There was a significant interaction between CMS and treatment (P-interaction = 0.03), for PFS, with hazard ratios (95% CI) for CB+CBM versus C arms in CMS1, 2, 3 and 4: 0.83 (0.43-1.62), 0.50 (0.33-0.76), 0.31 (0.13-0.75) and 1.24 (0.68-2.25), respectively.

CONCLUSIONS

This exploratory study found that CMS stratified OS outcomes in metastatic CRC regardless of first-line treatment, with prognostic effects of CMS groups distinct from those previously reported in early-stage cohorts. In CMS associations with treatment, CMS2 and possibly CMS3 tumours may preferentially benefit from the addition of bevacizumab to first-line capecitabine-based chemotherapy, compared with other CMS groups. Validation of these findings in additional cohorts is warranted.

CLINICAL TRIAL NUMBER

This is a molecular sub-study of MAX clinical trial (NCT00294359).

Nonlinear Model Predictive Control Using Robust Fixed Point Transformation-Based Phenomena for Controlling Tumor Growth

In this paper a novel control strategy is introduced in order to create optimal dosage profiles for individualized cancer treatment. This approach uses Nonlinear Model Predictive Control to construct optimal dosage protocols in conjunction with Robust Fixed Point Transformations which hinders the negative effect of inherent model uncertainties and measurement disturbances. The results are validated by extensive simulation on the proposed control algorithm from which conclusions were drawn.

An Improved In Vivo Methodology to Visualise Tumour Induced Changes in Vasculature Using the Chick Chorionic Allantoic Membrane Assay

BACKGROUND/AIM

Decreasing the vascularity of a tumour has proven to be an effective strategy to suppress tumour growth and metastasis. Anti-angiogenic therapies have revolutionized the treatment of advanced-stage cancers, however there is still demand for further improvement. This necessitates new experimental models that will allow researchers to reliably study aspects of angiogenesis. The aim of this study was to demonstrate an in vivo technique in which the highly vascular and accessible chorioallantoic membrane (CAM) of the chick embryo is used to study tumour-induced changes in the macro and microvessels.

MATERIALS AND METHODS

Two cancer cell lines (human melanoma (C8161) and human prostate cancer (PC3)) were selected as model cells. Human dermal fibroblasts were used as a control. One million cells were labelled with green fluorescent protein and implanted on the CAM of the chick embryo at embryonic development day (EDD) 7 and angiogenesis was evaluated at EDDs 10, 12 and 14. A fluorescently-tagged lectin (lens culinaris agglutinin (LCA)) was injected intravenously into the chick embryo to label endothelial cells. The LCA is known to label the luminal surface of endothelial cells, or dextrans, in the CAM vasculature. Macrovessels were imaged by a hand-held digital microscope and images were processed for quantification. Microvessels were evaluated by confocal microscopy. Tumour invasion was assessed by histological and optical sectioning.

RESULTS

Tumour cells (C8161 and PC3) produced quantifiable increases in the total area covered by blood vessels, compared to fibroblasts when assessed by digital microscopy. Tumour invasion could be demonstrated by both histological and optical sectioning. The most significant changes in tumour vasculature observed were in the microvascular structures adjacent to the tumour cells, which showed an increase in the endothelial cell coverage. Additionally, tumour intravasation and tumour thrombus formation could be detected in the areas adjacent to tumour cells. The fragility of tumour blood vessels could be demonstrated when tumour cells seeded on a synthetic scaffold were grown on CAM.

CONCLUSION

We report on a modification to a well-studied CAM in vivo assay, which can be effectively used to study tumour induced changes in macro and microvasculature.

Histopathologic patterns as markers of prognosis in patients undergoing hepatectomy for colorectal cancer liver metastases - Pushing growth as an independent risk factor for decreased survival

INTRODUCTION

Liver resection combined with neoadjuvant chemotherapy (NAC) has reported notable results in patients with colorectal liver metastases (CRLM). Tumoral response to NAC is associated with specific histopathologic patterns with prognostic implications. The main objective of this study was to evaluate the influence of pathological findings on overall survival (OS), disease-free survival (DFS) and liver recurrence-free survival (LRFS).

PATIENTS AND METHODS

Analysis of clinical and outcome data from 110 patients who underwent first CRLM resection between January 2010 and July 2013. Blinded pathological review of histological material of several parameters: resection margin, tumor regression grade (TRG), tumor thickness at the tumor-normal interface (TTNI) and the growth pattern (GP).

RESULTS

The median survival following hepatic resection was 52 months and 3- and 5- year Kaplan-Meier estimates were 69 and 48%, respectively. Seventy-four patients developed recurrent disease. Oxaliplatin-based chemotherapy was significantly associated with a pushing GP. A positive resection margin was an independent predictor of decreased DFS (p = 0.018) but not of decreased OS. LRFS was strongly reduced by the absence of histologic tumor response (p = 0.018). The pushing pattern had an adverse impact on both OS (p = 0.007) and DFS (p = 0.004) on multivariate analysis.

CONCLUSION

The prognostic value of histopathological features in patients who underwent CRLM's resection is undeniable. The pushing GP was related with worse prognosis. Further studies are required to clarify the biological mechanisms underlying these findings in order to enhance a more personalized and efficient treatment of these patients.

Circulating endothelial cells and microparticles as diagnostic and prognostic biomarkers in small-cell lung cancer

OBJECTIVES

It has been proposed that circulating endothelial cells (CECs) and microparticles (MPs) may be useful for the assessment of patients with non-small-cell lung cancer (NSCLC). However, little is known about the potential clinical relevance of these biomarkers in small-cell lung cancer (SCLC). Therefore, we investigated the utility of baseline levels of CECs and MPs in SCLC patients.

MATERIALS AND METHODS

An immunomagnetic separation (IMS) technique was used to isolate and quantify CECs in the peripheral blood, while plasma samples were analyzed using flow cytometry for the measurement of circulating MPs.

RESULTS

We prospectively collected data from 56 patients and 41 healthy individuals. Forty-three patients presented at initial diagnosis and 13 patients presented at relapse. Baseline levels of CECs and MPs were significantly higher in SCLC patients either at initial diagnosis or at relapse than in healthy subjects (p < 0.0002 and p < 0.007, respectively). However, estimated tumor volume (ETV) was significantly correlated with basal MP values (p < 0.0001) but not with pretreatment CECs (p =  0.57). The amount of baseline CECs and MPs was significantly lower in patients with an objective response (OR, n = 23) than in those with progressive disease (PD, n = 15) after treatment (p =  0.016 and 0.05, respectively). With cut-off values of 110 cells/mL for CECs and 1257 events/μL for MPs according to receiver operating characteristics (ROC) analysis, baseline levels of these biomarkers were not significantly correlated with either progression-free survival (PFS) or overall survival (OS). However, patients with 6-month PFS displayed significantly decreased pretreatment CEC counts (p =  0.042), whereas basal MP values significantly increased in 1-year survivors compared with those in non-survivors (p =  0.05).

CONCLUSION

Our results suggest that baseline CECs and MPs may be predictive biomarkers of tumor response and long-term survival in SCLC patients.

Anaerobic Growth and Maintenance of Mammalian Cell Lines

Most mucosal surfaces along with the midpoints in tumors and stem cell niches are geographic areas of the body that are anoxic. Previous studies show that the incubation in normoxic (5% CO2 in air) or hypoxic (low oxygen levels) conditions followed by an anoxic incubation (an absence of free oxygen) results in limited viability (2-3 days). A novel methodology was developed that enables an anoxic cell cultivation (for at least 17 days; the maximum time tested). The most critical aspect of this methodology is to ensure that no oxygen is introduced into the system. This is obtained by the degassing of media, and by flushing tubes, dishes, flasks, and pipettes with an anaerobic gas mixture (H2, CO2, N2) followed by permitting the materials to equilibrate to the anoxic (non-oxygen) environment prior to usage. Additional care must be exercised when acquiring photomicrographs to ensure that the micrographs obtained do not contain artifacts. In the absence of oxygen, cell morphology is significantly altered. Two distinct morphotypes are noted for all anaerobically-grown cells. The ability to grow and maintain mammalian cells in the absence of oxygen can be applied to the analysis of cell physiology, polymicrobial interactions, and the characterization of biosynthetic pathways for novel cancer drug development.

Angiogenesis in NSCLC: is vessel co-option the trunk that sustains the branches?

The critical role of angiogenesis in tumor development makes its inhibition a valuable new approach in therapy, rapidly making anti-angiogenesis a major focus in research. While the VEGF/VEGFR pathway is the main target of the approved anti-angiogenic molecules in NSCLC treatment, the results obtained are still modest, especially due to resistance mechanisms. Accumulating scientific data show that vessel co-option is an alternative mechanism to angiogenesis during tumor development in well-vascularized organs such as the lungs, where tumor cells highjack the existing vasculature to obtain its blood supply in a non-angiogenic fashion. This can explain the low/lack of response to current anti-angiogenic strategies. The same principle applies to lung metastases of other primary tumors. The exact mechanisms of vessel co-option need to be further elucidated, but it is known that the co-opted vessels regress by the action of Angiopoietin-2 (Ang-2), a vessel destabilizing cytokine expressed by the endothelial cells of the pre-existing mature vessels. In the absence of VEGF, vessel regression leads to tumor cell loss and hypoxia, with a subsequent switch to a neoangiogenic phenotype by the remaining tumor cells. Unravelling the vessel co-option mechanisms and involved players may be fruitful for numerous reasons, and the particularities of this form of vascularization should be carefully considered when planning anti-angiogenic interventions or designing clinical trials for this purpose. In view of the current knowledge, rationale for therapeutic approaches of dual inhibition of Ang-2 and VEGF are swiftly gaining strength and may serve as a launchpad to more successful NSCLC anti-vascular treatments.

Non-angiogenic tumours and their influence on cancer biology

Solid tumours need a blood supply, and a large body of evidence has previously suggested that they can grow only if they induce the development of new blood vessels, a process known as tumour angiogenesis. On the basis of this hypothesis, it was proposed that anti-angiogenic drugs should be able to suppress the growth of all solid tumours. However, clinical experience with anti-angiogenic agents has shown that this is not always the case. Reports of tumours growing without the formation of new vessels can be found in the literature dating back to the 1800s, yet no formal recognition, description and demonstration of their special biological status was made until recently. In 1996, we formally recognized and described non-angiogenic tumours in lungs where the only blood vessels present were those originating from normal lung tissue. This is far from an isolated scenario, as non-angiogenic tumour growth has now been observed in tumours of many different organs in both humans and preclinical animal models. In this Opinion article, we summarize how these tumours were discovered and discuss what we know so far about their biology and the potential implications of this knowledge for cancer treatment.

Foe or friend? Janus-faces of the neurovascular unit in the formation of brain metastases

Despite the potential obstacle represented by the blood-brain barrier for extravasating malignant cells, metastases are more frequent than primary tumors in the central nervous system. Not only tightly interconnected endothelial cells can hinder metastasis formation, other cells of the brain microenvironment (like astrocytes and microglia) can also be very hostile, destroying the large majority of metastatic cells. However, malignant cells that are able to overcome these harmful mechanisms may benefit from the shielding and even support provided by cerebral endothelial cells, astrocytes and microglia, rendering the brain a sanctuary site against anti-tumor strategies. Thus, cells of the neurovascular unit have a Janus-faced attitude towards brain metastatic cells, being both destructive and protective. In this review, we present the main mechanisms of brain metastasis formation, including those involved in extravasation through the brain vasculature and survival in the cerebral environment.

Endothelial progenitor cells contribute to neovascularization of non-small cell lung cancer via histone deacetylase 7-mediated cytoskeleton regulation and angiogenic genes transcription

To supply tumor tissues with nutrients and oxygen, endothelial progenitor cells (EPCs) home to tumor sites and contribute to neovascularization. Although the precise mechanism of EPCs-induced neovascularization remains poorly understood in non-small cell lung cancer (NSCLC), histone deacetylase 7 (HDAC7) is considered as a critical regulator. To explore the function of HDAC7 in neovascularization induced by EPCs, tube formation assay, immunofluorescence, microarray, Western blot analysis and animal models were performed. In vitro, HDAC7 abrogation led to the activation of Rho-associated coiled-coil containing protein kinase/myosin light chain 2 pathway concomitant with ERK dephosphorylation, causing the instability of cytoskeleton and collapse of tube formation. In vivo, absence of HDAC7 impaired the vascular lumen integrity and decreased the functional blood perfusion, inhibiting the growth of tumor. At the level of transcription, HDAC7 silencing upregulated antiangiogenic genes and suppressed proangiogenic genes collectively, turning off the angiogenic switch during vessel formation. Taken together, HDAC7 plays a dual role in maintaining the structural and nonstructural functions of EPCs. Our work demonstrates the molecular mechanism by which HDAC7 contributes to the angiogenic property of EPCs and provides a rational basis for specific targeting of antiangiogenic strategies in lung cancer.

Morphological Aspects of Tumor Angiogenesis

The tumor vasculature is a chaotic mixture of abnormal, hierarchically disorganized vessels that differ from those of normal tissues with respect to organization, structure and function. Firstly, tumor vessel wall structure is abnormal and heterogeneous within the tumor. Besides contractile wall components, the perivascular compartment is often lacking pericytes, what makes the tumor vessels fragile and leaky. Secondly, another group of abnormalities involves distortions in angioarchitecture and vasculature as network. Common features of tumor vessels, irrespective of their origin, size and growth pattern, are absence of hierarchical organization, formation of vessels with irregular contours and their heterogeneous distribution within the tumor.

Endothelial Progenitor Cells as Shuttle of Anticancer Agents

Cell therapies are treatments in which stem or progenitor cells are stimulated to differentiate into specialized cells able to home to and repair damaged tissues. After their discovery, endothelial progenitor cells (EPCs) stimulated worldwide interest as possible vehicles to perform autologous cell therapy of tumors. Taking into account the tumor-homing properties of EPCs, two different approaches to control cancer progression have been pursued by combining cell-based therapy with gene therapy or with nanomedicine. The first approach is based on the possibility of engineering EPCs to express different transgenes, and the second is based on the capacity of EPCs to take up nanomaterials. Here we review the most important progress covering the following issues: the characterization of bona fide endothelial progenitor cells, their role in tumor vascularization and metastasis, and preclinical data about their use in cell-based tumor therapy, considering antiangiogenic, suicide, immune-stimulating, and oncolytic virus gene therapy. The mixed approach of EPC cell therapy and nanomedicine is discussed in terms of plasmonic-dependent thermoablation and molecular imaging.

The role of CEUS in characterization of superficial lymph nodes: a single center prospective study

Accurate lymph node characterization is important in a large number of clinical settings. We evaluated the usefulness of Contrast Enhanced Ultrasound (CEUS) in distinguishing between benign and malignant lymph nodes compared with conventional ultrasonography in the differential diagnosis of superficial lymphadenopathy.

We present our experience for 111 patients enrolled in a single center.

111 superficial lymph nodes were selected and only 1 lymph node per patient underwent CEUS. A definitive diagnosis for all lymph nodes was obtained by ultrasonographically guided biopsy and/or excision biopsy.

The size of the lymph nodes, the site (neck, axilla, inguinal region) being easily accessible for biopsy, and the US and color Doppler US characteristics guided us in selecting the nodes to be evaluated by CEUS.

In our study we identified different enhancement patterns in benign and malignant lymph nodes, with a high degree of diagnostic accuracy for superficial lymphadenopathy in comparison with conventional US.

A method for the long-term cultivation of mammalian cells in the absence of oxygen: Characterization of cell replication, hypoxia-inducible factor expression and reactive oxygen species production

The center of tumors, stem cell niches and mucosal surfaces all represent areas of the body that are reported to be anoxic. However, long-term study of anoxic cell physiology is hindered by the lack of a sustainable method permitting cell cultivation in the complete absence of oxygen. A novel methodology was developed that enabled anoxic cell cultivation (17d maximum time tested) and cell passage. In the absence of oxygen, cell morphology is significantly altered. All cells tested exhibited morphologic changes, i.e., a combination of tethered (monolayer-like) and runagate (suspension-like) morphologies. Both morphologies replicated (Vero and HeLa cells tested) and could be passaged anaerobically. In the absence of exogenous oxygen, anoxic cells produced reactive oxygen species (ROS). Anaerobic runagate HeLa and Vero cells increased ROS production from day 3 to day 10 by 2- and 3-fold, respectively. In contrast, anoxic tethered HeLa and Vero cells either showed no significant change in ROS production between days 3 and 10 or exhibited a 3-fold decrease in ROS, respectively. Detection of ROS was inversely related to detection of hypoxia-inducible factor-1α (HIF1) mRNA and HIF-1 protein expression which cycled over a 10-day period. This methodology has broad applications for the study of tumor and stem cell physiology as well as gastrointestinal cell-microbiome interactions. In addition, sustainable anaerobic cell culture may lead to the identification of novel pathways and targets for chemotherapeutic drug development.

Modeling angiogenesis with micro- and nanotechnology

Angiogenesis plays an important role not only in the growth and regeneration of tissues in humans but also in pathological conditions such as inflammation, degenerative disease and the formation of tumors. Angiogenesis is also vital in thick engineered tissues and constructs, such as those for the heart and bone, as these can face difficulties in successful implantation if they are insufficiently vascularized or unable to connect to the host vasculature. Considerable research has been carried out on angiogenic processes using a variety of approaches. Pathological angiogenesis has been analyzed at the cellular level through investigation of cell migration and interactions, modeling tissue level interactions between engineered blood vessels and whole organs, and elucidating signaling pathways involved in different angiogenic stimuli. Approaches to regenerative angiogenesis in ischemic tissues or wound repair focus on the vascularization of tissues, which can be broadly classified into two categories: scaffolds to direct and facilitate tissue growth and targeted delivery of genes, cells, growth factors or drugs that promote the regeneration. With technological advancement, models have been designed and fabricated to recapitulate the innate microenvironment. Moreover, engineered constructs provide not only a scaffold for tissue ingrowth but a reservoir of agents that can be controllably released for therapeutic purposes. This review summarizes the current approaches for modeling pathological and regenerative angiogenesis in the context of micro-/nanotechnology and seeks to bridge these two seemingly distant aspects of angiogenesis. The ultimate aim is to provide insights and advances from various models in the realm of angiogenesis studies that can be applied to clinical situations.

MMP-2 and MMP-13 affect vasculogenic mimicry formation in large cell lung cancer

Matrix metalloproteinases (MMPs) have critical functions in tumour vasculogenic mimicry (VM). This study explored the mechanisms underlying MMP-13 and MMP-2 regulation of tumour VM formation in large cell lung cancer (LCLC). In our study, laminin5 (Ln-5) fragments cleaved by MMP-2 promoted tubular structure formation by the LCLC cell lines H460 and H661 in three-dimensional (3D) cultures. Transient up-regulation of MMP-13 or treatment with recombinant MMP-13 protein abrogated tubular structure formation of H460 cells in 3D culture. Treated cells with Ln-5 fragments cleaved by MMP-2 stimulated EGFR and F-actin expression. Ln-5 fragments cleaved by MMP-13 decreased EGFR/F-actin expression and disrupted VM formation. MMP-13 expression was negatively correlated with VM, Ln-5 and EGFR in LCLC tissues and xenograft. In vivo experiments revealed that VM was decreased when the number of endothelium-dependent vessels (EDVs) increased during xenograft tumour growth, whereas MMP-13 expression was progressively increased. In conclusion, MMP-2 promoted and MMP-13 disrupted VM formation in LCLC by cleaving Ln-5 to influence EGFR signal activation. MMP-13 may regulate VM and EDV formation.

Collateral Damage Intended-Cancer-Associated Fibroblasts and Vasculature Are Potential Targets in Cancer Therapy

After oncogenic transformation, tumor cells rewire their metabolism to obtain sufficient energy and biochemical building blocks for cell proliferation, even under hypoxic conditions. Glucose and glutamine become their major limiting nutritional demands. Instead of being autonomous, tumor cells change their immediate environment not only by their metabolites but also by mediators, such as juxtacrine cell contacts, chemokines and other cytokines. Thus, the tumor cells shape their microenvironment as well as induce resident cells, such as fibroblasts and endothelial cells (ECs), to support them. Fibroblasts differentiate into cancer-associated fibroblasts (CAFs), which produce a qualitatively and quantitatively different extracellular matrix (ECM). By their contractile power, they exert tensile forces onto this ECM, leading to increased intratumoral pressure. Moreover, along with enhanced cross-linkage of the ECM components, CAFs thus stiffen the ECM. Attracted by tumor cell- and CAF-secreted vascular endothelial growth factor (VEGF), ECs sprout from pre-existing blood vessels during tumor-induced angiogenesis. Tumor vessels are distinct from EC-lined vessels, because tumor cells integrate into the endothelium or even mimic and replace it in vasculogenic mimicry (VM) vessels. Not only the VM vessels but also the characteristically malformed EC-lined tumor vessels are typical for tumor tissue and may represent promising targets in cancer therapy.

Out of the frying pan and into the fire: damage-associated molecular patterns and cardiovascular toxicity following cancer therapy

Cardio-oncology is a new and rapidly expanding field that merges cancer and cardiovascular disease. Cardiovascular disease is an omnipresent side effect of cancer therapy; in fact, it is the second leading cause of death in cancer survivors after recurrent cancer. It has been well documented that many cancer chemotherapeutic agents cause cardiovascular toxicity. Nonetheless, the underlying cause of cancer therapy-induced cardiovascular toxicity is largely unknown. In this review, we discuss the potential role of damage-associated molecular patterns (DAMPs) as an underlying contributor to cancer therapy-induced cardiovascular toxicity. With an increasing number of cancer patients, as well as extended life expectancy, understanding the mechanisms underlying cancer therapy-induced cardiovascular disease is of the utmost importance to ensure that cancer is the only disease burden that cancer survivors have to endure.

Notch4 inhibition suppresses invasion and vasculogenic mimicry formation of hepatocellular carcinoma cells

Vasculogenic mimicry (VM) is a process by which aggressive tumor cells generate non-endothelial cell-lined channels in malignant tumors including hepatocellular carcinoma (HCC). It has provided new insights into tumor behavior and has surfaced as a potential target for drug therapy. The molecular events underlying the process of VM formation are still poorly understood. In this study, we attempted to elucidate the relationship between Notch4 and VM formation in HCC. An effective siRNA lentiviral vector targeting Notch4 was constructed and transfected into Bel7402, a HCC cell line. VM networks were observed with a microscope in a 3 dimensional cell culture system. Cell migration and invasion were evaluated using wound healing and transwell assays. Matrix metalloproteinases (MMPs) activity was detected by gelatin zymography. Furthermore, the role of Notch4 inhibition in Bel7402 cells in vivo was examined in subcutaneous xenograft tumor model of mice. The results showed that downregulation of Notch4 destroyed VM network formation and inhibited migration and invasion of tumor cells in vitro (P<0.05). In vivo, tumor growth was also inhibited in subcutaneous xenograft model (P<0.05). The potential mechanisms might be related with down-regulation of MT1-MMP, MMP-2, MMP-9 expression and inhibition of the activation of MMP2 and MMP9. These results indicated that Notch4 may play an important role in VM formation and tumor invasion in HCC. Related molecular pathways may be used as novel therapeutic targets for HCC antiangiogenesis therapy.

Bone Marrow Stroma and Vascular Contributions to Myeloma Bone Homing

PURPOSE OF THE REVIEW

Herein we dissect mechanisms behind the dissemination of cancer cells from primary tumor site to the bone marrow, which are necessary for metastasis development, with a specific focus on multiple myeloma.

RECENT FINDINGS

The ability of tumor cells to invade vessels and reach the systemic circulation is a fundamental process for metastasis development; however, the interaction between clonal cells and the surrounding microenvironment is equally important for supporting colonization, survival, and growth in the secondary sites of dissemination. The intrinsic propensity of tumor cells to recognize a favorable milieu where to establish secondary growth is the basis of the "seed and soil" theory. This theory assumes that certain tumor cells (the "seeds") have a specific affinity for the milieu of certain organs (the "soil"). Recent literature has highlighted the important contributions of the vascular niche to the hospitable "soil" within the bone marrow. In this review, we discuss the crucial role of stromal cells and endothelial cells in supporting primary growth, homing, and metastasis to the bone marrow, in the context of multiple myeloma, a plasma cell malignancy with the unique propensity to primarily grow and metastasize to the bone marrow.

Acidic stress induces apoptosis and inhibits angiogenesis in human bone marrow-derived endothelial progenitor cells

Bone marrow-derived endothelial progenitor cells (BM-EPCs) are exposed to acidotic environments in a variety of physiological and pathological conditions, including in tumors. However, the effect of acidosis on the function of BM-EPCs is still not fully understood. In the present study, BM-EPCs were isolated and cultured at an extracellular pH (pHe) of 6.5 or pHe 7.4 in vitro prior to various experiments being performed. Cellular proliferation, migration and tube formation ability were detected by DNA content quantification, Transwell assay and Matrigel-based angiogenesis assay. ELISA and western blot analysis measured protein secretion and expression, respectively. The results demonstrated that BM-EPCs cultured at pHe 6.5 compared with at pHe 7.4 demonstrated: Induced apoptosis; inhibited cellular proliferation, migration and adhesion; markedly reduced vascular endothelial growth factor (VEGF) expression; and the capacity to incorporate into vascular networks. Acidic pHe 6.5 induced ratio expression of B-cell lymphoma 2 (Bcl2)/Bcl2 associated X-protein (Bax), which in turn induced apoptosis, and inhibited cellular proliferation and other functional activities, with involvement of activation of VEGF receptor 2, protein kinase B and p38 mitogen activated protein kinase. These observations raise the possibility that the acidic extracellular environment may perform an important role in the vasculogenesis of BM-EPCs in tumor microenvironments. Therefore, culturing cancer cells at a lower pH that simulates endogenous tumor conditions may improve retention of the cellular heterogeneity identified in tumors.

Biological Pathways Involved in Tumor Angiogenesis and Bevacizumab Based Anti-Angiogenic Therapy with Special References to Ovarian Cancer

The creation of new blood vessels from existing ones, which is a mechanism called “angiogenesis”, is essential in cancer to supply cancerous growth. Moreover, the development and the progression of the tumor and its metastases are the result of an efficient vascular response. Cancer cells release and activate different angiogenic growth factors and their receptors in the tumor microenvironment to promote the angiogenic process. The most important pro-angiogenic factor is the “Vascular Endothelial Growth Factor” (VEGF) because of its mitogen activity on vascular endothelium. Bevacizumab is a monoclonal antibody that obstructs the binding of circulating vascular endothelial growth factor to its receptors and has been approved for the treatment of primary and recurrent ovarian cancer but also for many other solid tumors.

Florid Intussusceptive-like Microvascular Dysangiogenesis in a Preterm Lung

The cellular mechanisms underlying the microvascular dysangiogenesis of bronchopulmonary dysplasia (chronic lung disease of the newborn) remain largely undetermined. We report unusual pulmonary vascular findings in a 27-week-gestation male newborn who died on the second day of life from intractable respiratory failure, following a pregnancy complicated by prolonged membrane rupture and persistent severe oligohydramnios. As expected, postmortem examination revealed pulmonary hypoplasia (lung/body weight ratio: 2.23%; 10th percentile for 27 weeks: 2.59%). In addition, lung microscopy revealed complex networks of non-sprouting, tortuous, and bulbously dilated capillaries, randomly distributed in widened airspace septa. Anti-smooth muscle actin immunohistochemistry demonstrated immunoreactive central densities within capillary lumina, suggestive of intravascular pillar formation. The plexus-forming, non-sprouting type of angiogenesis and apparent transluminal pillar formation are consistent with intussusceptive ("longitudinal splitting") angiogenesis. In concordance with previous observations made in human fetal lung xenografts, these findings support the notion that human postcanalicular lungs have the capacity to switch from sprouting to non-sprouting, intussusceptive-like angiogenesis, possibly representing an adaptive response activated by hemodynamic flow alterations and/or hypoxia. The possible relationship between the intussusceptive-like vascular changes observed in this case and the microvascular dysangiogenesis characteristic of bronchopulmonary dysplasia remains to be determined.

Hostile takeover: how tumours hijack pre-existing vascular environments to thrive

An increasing body of evidence suggests that solid tumours do not require the generation of new blood vessels, i.e. angiogenesis, to successfully grow, and to colonize normal tissue. Instead, many tumour cells make the best use of what they find: pre-existing blood vessels of the host. In these cases, the host vasculature is incorporated by the growing tumour, resulting in a new organ consisting of malignant and non-malignant cell types. In consequence, pre-existing vessels are exploited by the tumour for optimal access to oxygen and nutrients. In this perspective article, the argument is made that tumour cells might gain even more: that is, access to the very special microenvironment of the perivascular niche. Here, specific cues for invasion, metastasis, survival, stem-like features, dormancy and, potentially, also immune escape exist - for non-malignant and malignant cells alike. The consequence of the hijacking of normal blood vessels and their perivascular niches by tumours is that antiangiogenic agents have little chance to work, and that tumour cells are better protected from the adverse effects of cytotoxic and targeted therapies. Thus, disturbing vascular hijacking could make tumours less resistant to established therapies. Concepts of how to do this are just starting to be explored. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Diagnostic relevance of metastatic renal cell carcinoma in the head and neck: An evaluation of 22 cases in 671 patients

Purpose

Renal cell carcinoma (RCC) is a malignant tumor that metastasizes early, and patients often present with metastatic disease at the time of diagnosis. The aim of our evaluation was to assess the diagnostic and differential diagnostic relevance of metastatic renal cell carcinoma (RCC) with particular emphasis on head and neck manifestations in a large patient series.

Patients and methods

We retrospectively evaluated 671 consecutive patients with RCC who were treated in our urology practice between 2000 and 2013.

Results

Twenty-four months after diagnosis, 200/671 (30%) of RCC had metastasized. Distant metastases were found in 172 cases, with 22 metastases (3.3%) in the head and neck. Cervical and cranial metastases were located in the lymph nodes (n=13) and in the parotid and the thyroid gland, tongue, the forehead skin, skull, and paranasal sinuses (n=9). All head and neck metastases were treated by surgical excision, with 14 patients receiving adjuvant radiotherapy and 9 patients receiving chemotherapy or targeted therapy at some point during the course of the disease. Five patients (23%) survived. The mean time of survival from diagnosis of a head and neck metastasis was 38 months, the shortest period of observation being 12 months and the longest 83 months.

Discussion and conclusion

Our findings show that while RCC metastases are rarely found in the neck, their proportion among distantly metastasized RCC amounts to 13%. Therefore, the neck should be included in staging investigations for RCC with distant metastases, and surgical management of neck disease considered in case of resectable metastatic disease. Similarly, in patients presenting with a neck mass with no corresponding tumor of the head and neck, a primary tumor below the clavicle should be considered and the appropriate staging investigations initiated.

Autophagy-induced KDR/VEGFR-2 activation promotes the formation of vasculogenic mimicry by glioma stem cells

Antiangiogenesis with bevacizumab, an antibody against vascular endothelial growth factor (VEGF), has been used for devascularization to limit the growth of malignant glioma. However, the benefits are transient due to elusive mechanisms underlying resistance to the antiangiogenic therapy. Glioma stem cells (GSCs) are capable of forming vasculogenic mimicry (VM), an alternative microvascular circulation independent of VEGF-driven angiogenesis. Herein, we report that the formation of VM was promoted by bevacizumab-induced macroautophagy/autophagy in GSCs, which was associated with tumor resistance to antiangiogenic therapy. We established a 3-dimensional collagen scaffold to examine the formation of VM and autophagy by GSCs, and found that rapamycin increased the number of VM and enhanced KDR/VEGFR-2 phosphorylation. Treatment with chloroquine, or knockdown of the autophagy gene ATG5, inhibited the formation of VM and KDR phosphorylation in GSCs. Notably, neutralization of GSCs-produced VEGF with bevacizumab failed to recapitulate the effect of chloroquine treatment and ATG5 knockdown, suggesting that autophagy-promoted formation of VM was independent of tumor cell-derived VEGF. ROS was elevated when autophagy was induced in GSCs and activated KDR phosphorylation through the phosphoinositide 3-kinase (PI3K)-AKT pathway. A ROS inhibitor, N-acetylcysteine, abolished KDR phosphorylation and the formation of VM by GSCs. By examination of the specimens from 95 patients with glioblastoma, we found that ATG5 and p-KDR expression was strongly associated with the density of VM in tumors and poor clinical outcome. Our results thus demonstrate a crucial role of autophagy in the formation of VM by GSCs, which may serve as a therapeutic target in drug-resistant glioma.