DEPDC1B Promotes Melanoma Angiogenesis and Metastasis through Sequestration of Ubiquitin Ligase CDC16 to Stabilize Secreted SCUBE3

The ability of melanoma to acquire metastasis through the induction of angiogenesis is one of the major causes of skin cancer death. Here, it is found that high transcript levels of DEP domain containing 1B (DEPDC1B) in cutaneous melanomas are significantly associated with a poor prognosis. Tissue microarray analysis indicates that DEPDC1B expression is positively correlated with SOX10 in the different stages of melanoma. Consistently, DEPDC1B is both required and sufficient for melanoma growth, metastasis, angiogenesis, and functions as a direct downstream target of SOX10 to partly mediate its oncogenic activity. In contrast to other tumor types, the DEPDC1B-mediated enhancement of melanoma metastatic potential is not dependent on the activities of RHO GTPase signaling and canonical Wnt signaling, but is acquired through secretion of signal peptide, CUB domain and EGF like domain containing 3 (SCUBE3), which is crucial for promoting angiogenesis in vitro and in vivo. Mechanistically, DEPDC1B regulates SCUBE3 protein stability through the competitive association with ubiquitin ligase cell division cycle 16 (CDC16) to prevent SCUBE3 from undergoing degradation via the ubiquitin-proteasome pathway. Importantly, expression of SOX10, DEPDC1B, and SCUBE3 are positively correlated with microvessel density in the advanced stage of melanomas. In conclusion, it is revealed that a SOX10-DEPDC1B-SCUBE3 regulatory axis promotes melanoma angiogenesis and metastasis, which suggests that targeting secreted SCUBE3 can be a therapeutic strategy against metastatic melanoma.

Down Syndrome Candidate Region 1 Isoform 1L regulated tumor growth by targeting both angiogenesis and tumor cells

Angiogenesis is critical for solid tumor growth beyond its minimal size. Previously, we reported that Down Syndrome Candidate Region 1 isoform 1L (DSCR1-1L) was one of the most up-regulated genes in endothelial cells induced by VEGF and histamine, and regulated endothelial cell proliferation, migration and angiogenesis. However, it was not known whether DSCR1-1L played a role in tumor growth. In this study, we found that DSCR1-1L shRNAs significantly inhibited the growth of transplanted melanoma in mice and its associated tumoral angiogenesis. In the gain of function assay, overexpression of DSCR1-1L cDNA in mouse endothelium is sufficient to significantly increase the tumor initiation induced by carcinogen, the growth of xenografted tumor, and the tumor metastasis in our endothelially-expressed DSCR1-1L transgenic mice, in which angiogenesis was induced. It was the first time to find that DSCR1-1L was also expressed in various tumor cells. DSCR1-1L shRNAs inhibited, but overexpression of DSCR1-1L cDNA increased, the tumor cell proliferation and migration. Most recently, we reported that DSCR1-1L modulated angiogenesis by down-regulation of VE-cadherin expression. Here, we found that DSCR1-1L down-regulated the expression of E-cadherin. Hence, DSCR1-1L is an excellent therapeutic target for cancers by regulation of both the endothelial and tumor cells through down-regulating (V)E-cadherin. DSCR1-1L shRNAs have the potential to be developed for clinical application.

Indocyanine Green Angiographic Assessment of Conjunctival Melanocytic Disorders

PURPOSE

To investigate whether transvascular indocyanine green (ICG) dye leakage is associated with conjunctival malignancy.

METHODS

This is a prospective interventional study. Patients presenting with circumscribed conjunctival melanocytic disorders (CMDs) were included and examined using color photography, anterior segment optical coherence tomography to measure lesion size, and fluorescein and ICG angiography to measure vascular pattern and leakage. Time to vascular leakage was measured by 2 independent observers. Lesions were characterized as benign or malignant based on histopathological features.

RESULTS

Thirty patients with CMD were included: 22 lesions were benign (conjunctival nevus, n = 20; conjunctival melanocytic intraepithelial neoplasia without atypia, n = 2) and 8 were malignant (in situ conjunctival melanoma n = 2; invasive conjunctival melanoma, n = 6). Malignant lesions had larger mean maximal diameters (11.0 ± 4.5 vs. 4.2 ± 2.5 mm, P = 0.003) and more frequently showed intrinsic tumor vasculature (8 of 8 vs. 10 of 22, P = 0.007). The mean time to ICG leakage was 350.9 ± 165.9 seconds in benign and 59.6 ± 22.1 seconds (P = 0.002) in malignant lesions and was inversely correlated with lesion size and thickness.

CONCLUSIONS

Time to angiographic ICG dye leakage is significantly shorter in malignant versus benign CMD.

The Roles of Extracellular Vesicles in Malignant Melanoma

Different types of cells, such as endothelial cells, tumor-associated fibroblasts, pericytes, and immune cells, release extracellular vesicles (EVs) in the tumor microenvironment. The components of EVs include proteins, DNA, RNA, and microRNA. One of the most important functions of EVs is the transfer of aforementioned bioactive molecules, which in cancer cells may affect tumor growth, progression, angiogenesis, and metastatic spread. Furthermore, EVs affect the presentation of antigens to immune cells via the transfer of nucleic acids, peptides, and proteins to recipient cells. Recent studies have also explored the potential application of EVs in cancer treatment. This review summarizes the mechanisms by which EVs regulate melanoma development, progression, and their potentials to be applied in therapy. We initially describe vesicle components; discuss their effects on proliferation, anti-melanoma immunity, and drug resistance; and finally focus on the effects of EV-derived microRNAs on melanoma pathobiology. This work aims to facilitate our understanding of the influence of EVs on melanoma biology and initiate ideas for the development of novel therapeutic strategies.

SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY IN SMALL CHOROIDAL MELANOMAS AND CHOROIDAL NEVI

PURPOSE

To evaluate the use of swept-source optical coherence tomography angiography to detect distinct vascular features in small choroidal melanomas and choroidal nevi.

METHODS

Patients with a choroidal nevus or a treatment-naïve choroidal melanoma were imaged with color fundus photography, ultrasound, and swept-source optical coherence tomography angiography (12 × 12 mm). High-risk features including overlying fluid, orange pigment, shaggy photoreceptors, acoustic hollowness, depth >2 mm, and basal diameter >5 mm were assessed. Optical coherence tomography angiography vascular markers included: choroidal vessel visualization, choroidal vessel depth, and choriocapillaris flow signal, assessed qualitatively by comparison with surrounding, unaffected choriocapillaris.

RESULTS

Twenty-nine lesions were included in this study, seven flat choroidal nevi, 17 elevated choroidal nevi, and 5 choroidal melanomas. Distinct vascular patterns were noted between flat nevi, elevated nevi, and small choroidal melanomas. Choroidal melanomas displayed two types of vasculature: "nevus-like" vasculature with straight parallel vessels and complex vasculature with vascular loops and crosslinking. Visualized choroidal vessels were significantly deeper in melanomas (110 µm) than elevated (84 µm) or flat nevi (70 µm). In a size-matched subanalysis of 5 elevated choroidal nevi and 5 choroidal melanomas, choroidal melanomas had increased mean choroidal vessel depth (P = 0.015), deepest choroidal vessel visualized (P = 0.034), and presence of a deep choroidal vessel >155 µm (P = 0.048).

CONCLUSION

Swept-source optical coherence tomography angiography may detect distinct vascular features in choroidal nevi and small choroidal melanomas.

Noncanonical EphA2 Signaling Is a Driver of Tumor-Endothelial Cell Interactions and Metastatic Dissemination in BRAF Inhibitor‒Resistant Melanoma

Acquired BRAF/MAPK/extracellular signal‒regulated kinase inhibitor resistance in melanoma results in a new transcriptional state associated with an increased risk of metastasis. In this study, we identified noncanonical ephrin receptor (Eph) EphA2 signaling as a driver of the resistance-associated metastatic state. We used mass spectrometry‒based proteomic and phenotypic assays to demonstrate that the expression of active noncanonical EphA2-S897E in melanoma cells led to a mesenchymal-to-amoeboid transition driven by Cdc42 activation. The induction of mesenchymal-to-amoeboid transition promoted melanoma cell invasion, survival under shear stress, adhesion to endothelial cells under continuous-flow conditions, increased permeability of endothelial cell monolayers, and stimulated melanoma transendothelial cell migration. In vivo, melanoma cells expressing EphA2-S897E or active Cdc42 showed superior lung retention after tail-vain injection. Analysis of BRAF inhibitor‒sensitive and ‒resistant melanoma cells demonstrated resistance to be associated with a mesenchymal-to-amoeboid transition switch, upregulation of Cdc42 activity, increased invasion, and transendothelial migration. The drug-resistant metastatic state was dependent on histone deacetylase 8 activity. Silencing of histone deacetylase 8 led to the inhibition of EphA2 and protein kinase B phosphorylation, reduced invasion, and impaired melanoma cell-endothelial cell interactions. In summary, we have demonstrated that the metastatic state associated with acquired BRAF inhibitor resistance is dependent on noncanonical EphA2 signaling, leading to increased melanoma-endothelial cell interactions and enhanced tumor dissemination.

Pericyte FAK negatively regulates Gas6/Axl signalling to suppress tumour angiogenesis and tumour growth

The overexpression of the protein tyrosine kinase, Focal adhesion kinase (FAK), in endothelial cells has implicated its requirement in angiogenesis and tumour growth, but how pericyte FAK regulates tumour angiogenesis is unknown. We show that pericyte FAK regulates tumour growth and angiogenesis in multiple mouse models of melanoma, lung carcinoma and pancreatic B-cell insulinoma and provide evidence that loss of pericyte FAK enhances Gas6-stimulated phosphorylation of the receptor tyrosine kinase, Axl with an upregulation of Cyr61, driving enhanced tumour growth. We further show that pericyte derived Cyr61 instructs tumour cells to elevate expression of the proangiogenic/protumourigenic transmembrane receptor Tissue Factor. Finally, in human melanoma we show that when 50% or more tumour blood vessels are pericyte-FAK negative, melanoma patients are stratified into those with increased tumour size, enhanced blood vessel density and metastasis. Overall our data uncover a previously unknown mechanism of tumour growth by pericytes that is controlled by pericyte FAK.

Gambogic acid exhibits anti-metastatic activity on malignant melanoma mainly through inhibition of PI3K/Akt and ERK signaling pathways

Gambogic acid (GA) is a potential anti-cancer compound that is extracted from the resin of Garciania hanburyi. The present study was designed to evaluate the anti-metastatic effect of GA on melanoma cell lines in vitro and to explore the underlying mechanism. The anti-proliferative activity of GA on melanoma cells was assessed by CCK-8 assay. The Wound-healing, transwell, adhesion, and tube formation assays were performed to examine the inhibition of GA on the cell's migration, invasion, adhesion, and angiogenesis capacities, respectively. Enzymatic activity of MMP-2 and MMP-9 were detected by gelatin zymography assay. Protein expressions regulated by GA treatment were tested by Western blot assay. The present results showed that GA significantly inhibited the proliferation of highly metastatic melanoma A375, B16-F10 cells and human umbilical vein endothelial cells (HUVECs) in time- and doses-dependent manners. Furthermore, GA significantly inhibited the migratory, invasive and adhesive properties of A375 and B16-F10 cells, and tube-forming potential of HUVECs at sub-IC50 concentrations, where no significant cytotoxicity was observed. Mechanistically, GA treatment suppressed the EMT and angiogenesis processes and reduced the enzymatic activity of MMP-2 and MMP-9. Moreover, abnormal PI3K/Akt and ERK signaling pathways in A375 and B16-F10 cells and HUVECs were notably suppressed by GA treatment. Collectively, our results suggest that GA exerts anti-metastasis activity in melanoma cells by suppressing the EMT and angiogenesis through the PI3K/Akt and ERK signaling pathways, and might be used as a phytomedicine against metastatic melanoma.

The role of vascular mimicry as a biomarker in malignant melanoma: a systematic review and meta-analysis

BACKGROUND

Vasculogenic mimicry (VM) a microvascular system consisting of non-endothelial cells that is newly formed by aggressive tumors, has been proposed as an important therapeutic target in malignant melanoma (MM). We performed a systematic literature review to evaluate the diagnostic and prognostic accuracy of VM status for overall survival of MM patients.

METHODS

The quality of the included studies was evaluated using the QUADAS-2 tool. Diagnostic capacity of VM variables, including sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and the area under summary receiver operating characteristic (SROC), were pooled using Meta-DiSc software.

RESULTS

A retrospective observational study was conducted based on twelve clinical studies including 978 clinically confirmed melanoma patients with proportion (P). VM+ melanoma cells were associated with poor prognosis in 38% of MM group (P = 0.35, 95% confidence intervals (CI): 0.27-0.42, p < 0.001). The pooled sensitivity and specificity were 0.82 (95% CI: 0.79-0.84) and 0.69 (95% CI: 0.66-0.71), respectively. Furthermore, the pooled PLR, NLR, and DOR were 2.56 (95% CI: 1.94-3.93), 0.17 (95% CI: 0.07-0.42), and 17.75 (95% CI: 5.30-59.44), respectively. Furthermore, the AUC of SROC was 0.63, indicating high reliability of VM status as a biomarker. Importantly, subgroup results suggested that VM+ status is a significantly accurate prognostic biomarker when diagnosed by the CD31-/PAS+ staining methods in Asian MM samples (p < 0.001).

CONCLUSIONS

Our findings support the potential of VM status of tumors as a promising prognostic biomarker and emphasize an effective adjuvant therapeutic strategy in the prognosis of Asian MM patients.

Density of PAS positive patterns in uveal melanoma: Correlation with vasculogenic mimicry, gene expression class, BAP-1 expression, macrophage infiltration, and risk for metastasis

Purpose

Periodic acid-Schiff (PAS) positive patterns of vasculogenic mimicry (VM) have been associated with poor prognosis in uveal melanoma (UM). We examined these patterns with digital image analysis and transmission electron microscopy, and correlated them with BAP-1 expression, gene expression class, macrophage infiltration, and metastatic disease in full tumor cross-sections and intratumor regions.

Methods

Thirty-two enucleated eyes with UM were stained immunohistochemically (BAP-1, laminin, CD31, and CD68) and with PAS without hematoxylin counterstain. Retrospective data on gene expression class and patient survival were retrieved. Tumor sections were digitally scanned and analyzed with the QuPath Bioimage analysis software, and imaged with transmission electron microscopy.

Results

The mean area proportion covered by CD31, laminin, and PAS positive patterns in tumor cross-sections was 0.9% (SD 0.6), 3.0% (SD 1.9), and 8.4% (SD 5.9), respectively. PAS density was statistically significantly greater in tumors with gene expression class 2 (p=0.02). The cumulative 5-year metastasis-free survival decreased for each quartile of increased PAS density (1.0, 0.75, 0.40, and 0.17, p=0.004). Forty percent of the tumors had heterogeneous BAP-1 expression. Intratumor regions with low BAP-1 expression were more likely to harbor VM (p<0.0001), and had statistically significantly greater PAS density (p<0.0001) and number of CD68 positive cells (p=0.01).

Conclusions

PAS positive patterns in UM are composed of a mixture of blood vessels and extracellular matrix (ECM), including VM. Increased density of PAS positive patterns correlated with gene expression class and metastasis, and colocated to tumor regions with macrophage infiltration and low BAP-1 expression.

Scutellarin inhibits the invasive potential of malignant melanoma cells through the suppression epithelial-mesenchymal transition and angiogenesis via the PI3K/Akt/mTOR signaling pathway

Malignant melanoma is the leading cause of death from skin disease, due in large part to its propensity to metastasize. Scutellarin is an active flavone extracted from traditional Chinese herb Erigeron breviscapus (Vant.) Hand. Mazz. Recent studies have reported that scutellarin can be utilized to treat various types of tumors. In this study, we investigated the effects of scutellarin on melanoma cancer cell invasive potential and the molecular mechanisms underlying these effects using A375 melanoma cells lines. The in-vitro antitumor activity of scutellarin was evaluated by CCK-8 assay, wound-healing assay, transwell assays, adhesion assays, and tube formation assays to assess the cell viability, migration, invasion, adhesion, and angiogenesis, respectively. Also, western blotting assay was used to assess the level of PI3K/Akt/mTOR signaling pathway proteins in A375 cells. We found that scutellarin significantly inhibited melanoma cell lines and HUVECs viability in a time- and concentration-dependent manners. Additionally, scutellarin effectively suppressed tumor cell migration, invasion, adhesion through the suppression of EMT and angiogenesis by inhibiting the PI3K/Akt/mTOR signaling pathway. These results indicated that scutellarin could markedly inhibit the invasive potential of melanoma cell lines by suppressing the EMT and angiogenesis through the PI3K/Akt/mTOR signaling pathway. It suggests that scutellarin might be a potential compound in malignant melanoma treatment.

Reduced CTL motility and activity in avascular tumor areas

Patchy infiltration of tumors by cytotoxic T cells (CTLs) predicts poorer prognosis for cancer patients. The factors limiting intratumoral CTL dissemination, though, are poorly understood. To study CTL dissemination in tumors, we histologically examined human melanoma samples and used mice to image B16-OVA tumors infiltrated by OT-I CTLs using intravital two-photon microscopy. In patients, most CTLs concentrated around peripheral blood vessels, especially in poorly infiltrated tumors. In mice, OT-I CTLs had to cluster around tumor cells to efficiently kill them in a contact-and perforin-dependent manner and cytotoxicity was strictly antigen-specific. OT-I CTLs as well as non-specific CTLs concentrated around peripheral vessels, and cleared the tumor cells around them. This was also the case when CTLs were injected directly into the tumors. CTLs crawled rapidly only in areas within 50 µm of flowing blood vessels and transient occlusion of vessels immediately, though reversibly, stopped their migration. In vitro, oxygen depletion and blockade of oxidative phosphorylation also reduced CTL motility. Taken together, these results suggest that hypoxia limits CTL migration away from blood vessels, providing immune-privileged niches for tumor cells to survive. Normalizing intratumoral vasculature may thus synergize with tumor immunotherapy.

Herbacetin suppressed MMP9 mediated angiogenesis of malignant melanoma through blocking EGFR-ERK/AKT signaling pathway

Malignant melanoma remains a challenge for clinical practice and novel therapeutic strategies are urgently needed. Herbacetin, a natural flavonoid compound that has multiple pharmacological activities, exerts anticancer effects on several human tumors. In this study, the anti-angiogenesis effect of Herbacetin in human malignant melanoma was investigated. The results indicated that Herbacetin treatment significantly suppressed tumor growth and angiogenesis of malignant melanoma both in vitro and in vivo. In melanoma A375 and Hs294T cells, Herbacetin treatment suppressed both EGF-induced and constitutive phosphorylation of EGFR, accelerated the internalization and degradation of EGFR, and subsequently suppressed the activation of the downstream kinases (AKT and ERK). Moreover, MMP9 was determined as a key angiogenic factor in Herbacetin treated melanoma cells. Knockdown of MMP9 suppressed the in vitro angiogenesis while overexpression of MMP9 in Herbacetin treated melanoma cells restored the angiogenesis ability. We concluded that Herbacetin suppressed melanoma angiogenesis through blocking EGFR-ERK/AKT-MMP9 signaling pathway and Herbacetin may be developed as a potential drug for melanoma treatment.

Quantitative analysis on in vivo tumor-microvascular images from optical-resolution photoacoustic microscopy

Optical-resolution photoacoustic microscopy (OR-PAM) has been shown to be an excellent imaging modality for monitoring and study of tumor microvasculature. However, previous studies focused mainly on the normal tissues and did not quantify the tumor microvasculature. In this study, we present an in vivo OR-PAM imaging of the melanomas and hepatoma implanted in the mouse ear. We quantify the vessel growth by extracting the skeletons of both dense and thin branches of the tumor microvasculature obtained by Hessian matrix enhancement followed by improved two-step multistencils fast marching method. Compared with the previous methods of using OR-PAM for normal tissues, our method was more effective in extracting the binary vascular network in the tumor images and in obtaining the complete and continuous microvascular skeleton maps. Our demonstration of using OR-PAM in improving microvasculature of tumors and quantification of tumor growth would push deep this technology for the early diagnosis and treatment of cancers.

Coupling tumor growth and bio distribution models

We couple a tumor growth model embedded in a microenvironment, with a bio distribution model able to simulate a whole organ. The growth model yields the evolution of tumor cell population, of the differential pressure between cell populations, of porosity of ECM, of consumption of nutrients due to tumor growth, of angiogenesis, and related growth factors as function of the locally available nutrient. The bio distribution model on the other hand operates on a frozen geometry but yields a much refined distribution of nutrient and other molecules. The combination of both models will enable simulating the growth of a tumor in a whole organ, including a realistic distribution of therapeutic agents and allow hence to evaluate the efficacy of these agents.

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.

Gold Nanoprisms as Optical Coherence Tomography Contrast Agents in the Second Near-Infrared Window for Enhanced Angiography in Live Animals

Optical coherence tomography angiography (OCTA) is an important tool for investigating vascular networks and microcirculation in living tissue. Traditional OCTA detects blood vessels via intravascular dynamic scattering signals derived from the movements of red blood cells (RBCs). However, the low hematocrit and long latency between RBCs in capillaries make these OCTA signals discontinuous, leading to incomplete mapping of the vascular networks. OCTA imaging of microvascular circulation is particularly challenging in tumors due to the abnormally slow blood flow in angiogenic tumor vessels and strong attenuation of light by tumor tissue. Here, we demonstrate in vivo that gold nanoprisms (GNPRs) can be used as OCT contrast agents working in the second near-infrared window, significantly enhancing the dynamic scattering signals in microvessels and improving the sensitivity of OCTA in skin tissue and melanoma tumors in live mice. With GNPRs as contrast agents, the postinjection OCT angiograms showed 41 and 59% more microvasculature than preinjection angiograms in healthy mouse skin and melanoma tumors, respectively. By enabling better characterization of microvascular circulation in vivo, GNPR-enhanced OCTA could lead to better understanding of vascular functions during pathological conditions, more accurate measurements of therapeutic response, and improved patient prognoses.

Tissue-engineered 3D melanoma model with blood and lymphatic capillaries for drug development

While being the rarest skin cancer, melanoma is also the deadliest. To further drug discovery and improve clinical translation, new human cell-based in vitro models are needed. Our work strives to mimic the melanoma microenvironment in vitro as an alternative to animal testing. We used the self-assembly method to produce a 3D human melanoma model exempt of exogenous biomaterial. This model is based on primary human skin cells and melanoma cell lines while including a key feature for tumor progression: blood and lymphatic capillaries. Major components of the tumor microenvironment such as capillaries, human extracellular matrix, a stratified epidermis (involucrin, filaggrin) and basement membrane (laminin 332) are recapitulated in vitro. We demonstrate the persistence of CD31+ blood and podoplanin+/LYVE-1+ lymphatic capillaries in the engineered tissue. Chronic treatment with vemurafenib was applied to the model and elicited a dose-dependent response on proliferation and apoptosis, making it a promising tool to test new compounds in a human-like environment.

Correlation of Microcirculation Architecture with Ultrasound Backscatter Parameters of Uveal Melanoma

Ultrasound tissue characterization parameters of size and acoustic concentration can be used to sub-classify uveal melanoma and estimate the patient's risk of death. Histologically determined microcirculation patterns have also been found to sub-classify uveal melanoma and predict patient's risk of death. This study examines the spatial relationship between tumor features detected by the two techniques. Three dimensional ultrasound images that depict the size and relative concentration of scattering elements in uveal melanoma within a range of approximately 50-120 microns were compared with PAS (without hematoxylin) stained histological sections graded and localized according to tumor microvascular patterns. Both ultrasound parameter imaging and histopathology were accomplished by workers masked to the other procedure. In three of five patients vascular networks were identified histopathologically. The predominant ultrasound feature seen in the regions of the histologically identified networks were clusters of scatterers in the range of approximately 50-80 microns. In the two cases without a network vascular pattern, lower range scatterers dominated the tumor volume. All the cases could be distinguished by the size and distribution of contiguous spatial clusters of acoustic scatterers. Scatterer size features detected in three dimensional ultrasound parameter images can identify tumor regions containing a specific microvascular pattern. Ultrasound tissue characterization features used to sub-classify uveal melanoma may have a biophysical basis related to patterns of tumor microcirculation.

Overexpression of Receptor Tyrosine Kinase EphB4 Triggers Tumor Growth and Hypoxia in A375 Melanoma Xenografts: Insights from Multitracer Small Animal Imaging Experiments

Experimental evidence has associated receptor tyrosine kinase EphB4 with tumor angiogenesis also in malignant melanoma. Considering the limited in vivo data available, we have conducted a systematic multitracer and multimodal imaging investigation in EphB4-overexpressing and mock-transfected A375 melanoma xenografts. Tumor growth, perfusion, and hypoxia were investigated by positron emission tomography. Vascularization was investigated by fluorescence imaging in vivo and ex vivo. The approach was completed by magnetic resonance imaging, radioluminography ex vivo, and immunohistochemical staining for blood and lymph vessel markers. Results revealed EphB4 to be a positive regulator of A375 melanoma growth, but a negative regulator of tumor vascularization. Resulting in increased hypoxia, this physiological characteristic is considered as highly unfavorable for melanoma prognosis and therapy outcome. Lymphangiogenesis, by contrast, was not influenced by EphB4 overexpression. In order to distinguish between EphB4 forward and EphrinB2, the natural EphB4 ligand, reverse signaling a specific EphB4 kinase inhibitor was applied. Blocking experiments show EphrinB2 reverse signaling rather than EphB4 forward signaling to be responsible for the observed effects. In conclusion, functional expression of EphB4 is considered a promising differentiating characteristic, preferentially determined by non-invasive in vivo imaging, which may improve personalized theranostics of malignant melanoma.

Effects of ursolic and oleanolic on SK‑MEL‑2 melanoma cells: In vitro and in vivo assays

Among the triterpenoids, oleanolic acid (OA) and its isomer, ursolic acid (UA) are promising therapeutic candidates, with potential benefits in the management of melanoma. In this study, we aimed to examine the in vitro and in vivo anti‑invasive and anti‑metastatic activity of OA and UA to determine their possible usefulness as chemopreventive or chemotherapeutic agents in melanoma. For the in vitro experiments, the anti‑proliferative activity of the triterpenic compounds on SK‑MEL‑2 melanoma cells was examined. The anti‑invasive potential was assessed by testing the effects of the active compound on vascular cell adhesion molecule (VCAM) and intercellular adhesion molecule (ICAM) adhesion to melanoma cells. Normal and tumor angiogenesis were evaluated in vivo by chicken embryo chorioallantoic membrane (CAM) assay. The two test triterpenoid acids, UA and OA, exerted differential effects in vitro and in vivo on the SK‑MEL‑2 melanoma cells. UA exerted a significant and dose‑dependent anti‑proliferative effect in vitro, compared to OA. The cytotoxic effects in vitro on the melanoma cells were determined by the examining alterations in the cell cycle phases induced by UA that lead to cell arrest in the S phase. Moreover, UA was found to affect SK‑MEL‑2 melanoma cell invasiveness by limiting the cell adhesion capacity to ICAM molecules, but not influencing their adhesion to VCAM molecules. On the whole, in this study, by assessing the effects of the two triterpenoids in vivo, our results revealed that OA had a greater potential to impair the invasive capacity and tumor angiogenesis compared with UA.

Metastatic pathway and the microvascular and physicochemical microenvironments of human melanoma xenografts

BACKGROUND

Malignant melanoma of the skin can metastasize through blood vessels and lymphatics. The primary tumor develops a vascular microenvironment characterized by abnormal blood vessels and lymphatics and a physicochemical microenvironment characterized by low oxygen tension, regions with hypoxic tissue, and high interstitial fluid pressure (IFP). This study aimed at identifying relationships between the metastatic route of melanomas and characteristic features of the microvascular and physicochemical microenvironments of the primary tumor.

METHODS

Two patient-derived xenograft (PDX) models (E-13, N-15) and four cell line-derived xenografts (CDX) models (C-10, D-12, R-18, T-22) of human melanoma were included in the study. Tumors were transplanted to an orthotopic site in BALB/c-nu/nu mice, and when the tumors had grown to a volume of 500-600 mm3, the IFP of the primary tumor was measured and the hypoxia marker pimonidazole was administered before the host mouse was euthanized. The primary tumor, lungs, and six pairs of lymph nodes were evaluated by examining hematoxylin/eosin-stained and immunostained histological preparations. The expression of angiogenesis-related genes was assessed by quantitative PCR.

RESULTS

C-10, D-12, and E-13 tumors disseminated primarily by the hematogenous route and developed pulmonary metastases. These tumors showed high angiogenic activity and high expression of the F3 gene as well as ANGPT2 and TIE1, genes encoding proteins of the angiopoietin-tie system. N-15, R-18, and T-22 tumors disseminated mainly by the lymphogenous route and developed metastases in draining lymph nodes. These tumors had highly elevated IFP and showed high expression of NRP2, a gene encoding neuropilin-2.

CONCLUSION

The primary metastatic route of orthotopic human melanoma xenografts and the development of lung and lymph node metastases are influenced significantly by the microvascular and physicochemical microenvironments of the primary tumor.

Focal Adhesion Kinase (FAK) tyrosine 397E mutation restores the vascular leakage defect in endothelium-specific FAK-kinase dead mice

Focal adhesion kinase (FAK) inhibitors have been developed as potential anticancer agents and are undergoing clinical trials. In vitro activation of the FAK kinase domain triggers autophosphorylation of Y397, Src activation, and subsequent phosphorylation of other FAK tyrosine residues. However, how FAK Y397 mutations affect FAK kinase-dead (KD) phenotypes in tumour angiogenesis in vivo is unknown. We developed three Pdgfb-iCreert -driven endothelial cell (EC)-specific, tamoxifen-inducible homozygous mutant mouse lines: FAK wild-type (WT), FAK KD, and FAK double mutant (DM), i.e. KD with a putatively phosphomimetic Y397E mutation. These ECCre+;FAKWT/WT , ECCre+;FAKKD/KD and ECCre+;FAKDM/DM mice were injected subcutaneously with syngeneic B16F0 melanoma cells. Tumour growth and tumour blood vessel functions were unchanged between ECCre+;FAKWT/WT and ECCre-;FAKWT/WT control mice. In contrast, tumour growth and vessel density were decreased in ECCre+;FAKKD/KD and ECCre+;FAKDM/DM mice, as compared with Cre - littermates. Despite no change in the percentage of perfused vessels or pericyte coverage in either genotype, tumour hypoxia was elevated in ECCre+;FAKKD/KD and ECCre+;FAKDM/DM mice. Furthermore, although ECCre+;FAKKD/KD mice showed reduced blood vessel leakage, ECCre+;FAKDM/DM and ECCre-;FAKDM/DM mice showed no difference in leakage. Mechanistically, fibronectin-stimulated Y397 autophosphorylation was reduced in Cre+;FAKKD/KD ECs as compared with Cre+;FAKWT/WT cells, with no change in phosphorylation of the known Src targets FAK-Y577, FAK-Y861, FAK-Y925, paxillin-Y118, p130Cas-Y410. Cre+;FAKDM/DM ECs showed decreased Src target phosphorylation levels, suggesting that the Y397E substitution actually disrupted Src activation. Reduced VE-cadherin-pY658 levels in Cre+;FAKKD/KD ECs were rescued in Cre+FAKDM/DM ECs, corresponding with the rescue in vessel leakage in the ECCre+;FAKDM/DM mice. We show that EC-specific FAK kinase activity is required for tumour growth, angiogenesis, and vascular permeability. The ECCre+;FAKDM/DM mice restored the KD-dependent tumour vascular leakage observed in ECCre+;FAKKD/KD mice in vivo. This study opens new fields in in vivo FAK signalling. © 2017 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

The Long Non-Coding RNA RHPN1-AS1 Promotes Uveal Melanoma Progression

Increasing evidence suggests that aberrant long non-coding RNAs (lncRNAs) are significantly correlated with the pathogenesis, development and metastasis of cancers. RHPN1 antisense RNA 1 (RHPN1-AS1) is a 2030-bp transcript originating from human chromosome 8q24. However, the role of RHPN1-AS1 in uveal melanoma (UM) remains to be clarified. In this study, we aimed to elucidate the molecular function of RHPN1-AS1 in UM. The RNA levels of RHPN1-AS1 in UM cell lines were examined using the quantitative real-time polymerase chain reaction (qRT-PCR). Short interfering RNAs (siRNAs) were designed to quench RHPN1-AS1 expression, and UM cells stably expressing short hairpin (sh) RHPN1-AS1 were established. Next, the cell proliferation and migration abilities were determined using a colony formation assay and a transwell migration/invasion assay. A tumor xenograft model in nude mice was established to confirm the function of RHPN1-AS1 in vivo. RHPN1-AS1 was significantly upregulated in a number of UM cell lines compared with the normal human retinal pigment epithelium (RPE) cell line. RHPN1-AS1 knockdown significantly inhibited UM cell proliferation and migration in vitro and in vivo. Our data suggest that RHPN1-AS1 could be an oncoRNA in UM, which may serve as a candidate prognostic biomarker and target for new therapies in malignant UM.

Synthesis and Biological Evaluation of N-[2-(4-Hydroxyphenylamino)-pyridin-3-yl]-4-methoxy-benzenesulfonamide (ABT-751) Tricyclic Analogues as Antimitotic and Antivascular Agents with Potent in Vivo Antitumor Activity

Benzopyridothiadiazepine (2a) and benzopyridooxathiazepine (2b) were modified to produce tricyclic quinazolinone 15-18 or benzothiadiazine 26-27 derivatives. These compounds were evaluated in cytotoxicity and tubulin inhibition assays and led to potent inhibitors of tubulin polymerization. N-[2(4-Methoxyphenyl)ethyl]-1,2-dihydro-pyrimidino[2,1-b]quinazolin-6-one (16a) exhibited the best in vitro cytotoxic activity (GI50 10-66.9 nM) against the NCI 60 human tumor cell line and significant potency against tubulin assembly (IC50 0.812 μM). In mechanism studies, 16a was shown to block cell cycle in G2/M phase and to disrupt microtubule formation and displayed good antivascular properties as inhibition of cell migration, invasion, and endothelial tube formation. Compound 16a was evaluated in C57BL/6 mouse melanoma B16F10 xenograft model to validate its antitumor activity, in comparison with reference ABT-751 (1). Compound 16a displayed strong in vivo antitumor and antivascular activities at a dose of 5 mg/kg without obvious toxicity, whereas 1 needed a 10-fold higher concentration to reach similar effects.

Expression of Heat Shock Protein 27 in Melanoma Metastases Is Associated with Overall Response to Bevacizumab Monotherapy: Analyses of Predictive Markers in a Clinical Phase II Study

The aim of this study was to identify potential predictive biomarkers in 35 patients with metastatic melanoma treated with anti-angiogenic bevacizumab monotherapy in a clinical phase II study. The immunohistochemical expression of various angiogenic factors in tissues from primary melanomas and metastases as well as their concentration in blood samples were examined. Strong expression of Heat Shock Protein 27 (HSP27) in metastases correlated significantly with complete or partial response to bevacizumab (p = 0.044). Furthermore, clinical benefit, i.e., complete or partial response or stable disease for at least 6 months, was more frequent in patients with strong expression of HSP27 in primary tumors (p = 0.046). Tissue expression of vascular endothelial growth factor (VEGF-A), its splicing variant VEGF165b or basic fibroblast growth factor (bFGF) did not correlate with response, and the concentration of HSP27, VEGF-A or bFGF measured in blood samples before treatment did not show predictive value. Further, microvessel density, proliferating microvessel density and presence of glomeruloid microvascular proliferations were assessed in sections of primary tumors and metastases. Microvessel density in primary melanomas was significantly higher in patients with clinical benefit than in non-responders (p = 0.042). In conclusion, our findings suggest that strong HSP27 expression in melanoma metastases predicts response to bevacizumab treatment.

Speckle-variance optical coherence tomography: a novel approach to skin cancer characterization using vascular patterns

Non-invasive imaging devices are currently being utilized in research and clinical settings to help visualize, characterize, anddiagnose cancers of the skin. Speckle-variance optical coherence tomography (svOCT) is one such technology that offers considerable promise for non-invasive, real time detection of skin cancers given its added ability to show changes in microvasculature. We present four early lesions of the face namely sebaceous hyperplasia, basal cell skin cancer, pigmented actinic keratosis, and malignant melanoma in situ that each display different important identification markers on svOCT. Up until now, svOCT has mainly been evaluated for lesion diagnosis using transversal (vertical) sections. Our preliminary svOCT findings use dynamic en face (horizontal) visualization to differentiate lesions based on their specific vascular organizations. These observed patterns further elucidate the potential of this imaging device to become a powerful tool in patient disease assessment.

Imaging of Angiotropism/Vascular Co-Option in a Murine Model of Brain Melanoma: Implications for Melanoma Progression along Extravascular Pathways

Angiotropism/pericytic mimicry and vascular co-option involve tumor cell interactions with the abluminal vascular surface. These two phenomena may be closely related. However, investigations of the two processes have developed in an independent fashion and different explanations offered as to their biological nature. Angiotropism describes the propensity of tumor cells to spread distantly via continuous migration along abluminal vascular surfaces, or extravascular migratory metastasis (EVMM). Vascular co-option has been proposed as an alternative mechanism by which tumors cells may gain access to a blood supply. We have used a murine brain melanoma model to analyze the interactions of GFP human melanoma cells injected into the mouse brain with red fluorescent lectin-labeled microvascular channels. Results have shown a striking spread of melanoma cells along preexisting microvascular channels and features of both vascular co-option and angiotropism/pericytic mimicry. This study has also documented the perivascular expression of Serpin B2 by angiotropic melanoma cells in the murine brain and in human melanoma brain metastases. Our findings suggest that vascular co-option and angiotropism/pericytic mimicry are closely related if not identical processes. Further studies are needed in order to establish whether EVMM is an alternative form of cancer metastasis in addition to intravascular cancer dissemination.

Biomarker Analysis in a Phase II Study of Sunitinib in Patients with Advanced Melanoma

AIM

To investigate the efficacy of sunitinib in patients with advanced melanoma and to correlate angiogenic biomarkers with response and survival.

PATIENTS AND METHODS

We performed a phase II study in patients with advanced pre-treated melanoma. The primary endpoint was tumor response. Blood samples for biomarker analysis including vascular endothelial growth factor (VEGF), and its receptors VEGFR1 and -2, placental growth factor (PlGF) and circulating endothelial cells (CEC) were collected at baseline and during the first cycle.

RESULTS

Four out of 39 patients (13%) achieved a partial response and eight (26%) stable disease. Time to progression was at least six months in seven patients. High baseline VEGFR1 levels and high baseline PlGF levels were both associated with a non-significant worse survival (p=0.08 for both).

CONCLUSION

Sunitinib demonstrates limited activity in unselected patients with refractory advanced melanoma, but a minority of patients experienced long-term disease control. Identification of these patients remains a challenge.

Peritumoral D2-40 Chalkley score independently predicts metastases and survival in patients with cutaneous malignant melanoma

BACKGROUND

Many observational studies investigated the prognostic significance of angiogenesis and lymphangiogenesis in patients with melanoma. However, the obtained results are rather contradictory, probably due to the lack of the consensus methodology.

METHODS

To investigate the prognostic significance of angiogenesis and lymphangiogenesis-related parameters in patients with melanoma, we performed a retrospective investigation following the consensus recommendations for angiogenesis and lymphangiogenesis quantification in solid tumors and reporting recommendations for tumor marker (REMARK) criteria for reporting the results. Blood and lymphatic vessel Chalkley scores, endothelial cell proliferation fractions and microvessel densities were quantified using a double immunostaining for endothelial marker CD34 or lymphendothelial marker D240 and the proliferation marker Ki-67 in 196 patients with melanoma. These parameters were evaluated separately for peritumoral (PT) and intratumoral areas and were correlated with outcome.

RESULTS

In multivariate analysis PT D240 Chalkley score was identified as a strongest predictor for sentinel lymph node metastases, non-sentinel lymph node metastases, distant metastases, disease free survival and overall survival in patients with melanoma.

CONCLUSIONS

If additional studies corroborate our findings, we believe that the inclusion of PT D240 Chalkley counts to the routine pathology examination of melanoma samples would provide additional information for identifying high-risk patients.

Defining the dermoscopic characteristics of fast-growing cutaneous melanomas

A high growth rate in melanomas has been associated with a more aggressive phenotype and worse survival. The aim of this study was to define the dermoscopic characteristics associated with this type of cutaneous melanoma. We carried out a retrospective study of 132 cutaneous melanomas, analyzing certain clinical characteristics and the most important dermoscopic variables related to the melanomas. Fast-growing melanomas were considered to be those with a growth rate of more than 0.5 mm per month. Fast-growing melanomas more often lacked an atypical network, were symmetrical, presented ulceration, and were hypopigmented. The dermoscopic vascular pattern often showed atypical irregular vessels and milky-red areas. The association of these two is a specific characteristic. Fast-growing melanomas have a characteristic phenotype and dermoscopy can be useful for their identification.

Vasculogenic mimicry: lessons from melanocytic tumors

Tumor cell vasculogenic mimicry refers to the formation of tumor cell-lined vessels that contribute to tumor neovascularization and nutrient and oxygen supply. These tumor cells express many endothelial and stem cell markers, resulting in them having a unique phenotype. This phenomenon is observed in a variety of neoplasms, such as glioblastomas and sarcomas, as well as breast, ovarian, liver and lung carcinomas. It is also evident in melanocytic lesions, regardless of their benign or malignant nature. The biochemical and molecular events that regulate vasculogenic mimicry provide opportunities for development of novel forms of tumor-targeted treatments. Furthermore, the presence of this process in a tumor might have prognostic implications.

The changes of angiogenesis and immune cell infiltration in the intra- and peri-tumoral melanoma microenvironment

Malignant melanoma (MM) urgently needs identification of new markers with better predictive value than currently-used clinical and histological parameters. Cancer cells stimulate the formation of a specialized tumor microenvironment, which reciprocally affects uncontrolled proliferation and migration. However, this microenvironment is heterogeneous with different sub-compartments defined by their access to oxygen and nutrients. This study evaluated microvascular density (MVD), CD3+ lymphocytes (TILs) and FOXP3+ T-regulatory lymphocytes (Tregs) on formalin-fixed paraffin-embedded tissue sections using light microscopy. We analyzed 82 malignant melanomas, divided according to the AJCC TNM classification into four groups--pT1 (35), pT2 (17), pT3 (18) and pT4 (12)--and 25 benign pigmented nevi. All parameters were measured in both the central areas of tumors (C) and at their periphery (P). A marked increase in all parameters was found in melanomas compared to nevi (p = 0.0001). There was a positive correlation between MVD, TILs, FOXP3+ Tregs and the vertical growth phase. The results show that MVD, TILs and FOXP3+ Tregs substantially influence cutaneous melanoma microenvironment. We found significant topographic differences of the parameters between central areas of tumors and their boundaries.

Pushing the optical imaging limits of cancer with multi-frequency-band raster-scan optoacoustic mesoscopy (RSOM)

Angiogenesis is a central cancer hallmark, necessary for supporting tumor growth and metastasis. In vivo imaging of angiogenesis is commonly applied, to understand dynamic processes in cancer development and treatment strategies. However, most radiological modalities today assess angiogenesis based on indirect mechanisms, such as the rate of contrast enhancement after contrast agent administration. We studied the performance of raster-scan optoacoustic mesoscopy (RSOM), to directly reveal the vascular network supporting melanoma growth in vivo, at 50 MHz and 100 MHz, through several millimeters of tumor depth. After comparing the performance at each frequency, we recorded, for the first time, high-resolution images of melanin tumor vasculature development in vivo, over a period of several days. Image validation was provided by means of cryo-slice sections of the same tumor after sacrificing the mice. We show how optoacoustic (photoacoustic) mesoscopy reveals a potentially powerful look into tumor angiogenesis, with properties and features that are markedly different than other radiological modalities. This will facilitate a better understanding of tumor's angiogenesis, and the evaluation of treatment strategies.

Microvessel density, lymphovascular density, and lymphovascular invasion in primary cutaneous melanoma-correlation with histopathologic prognosticators and BRAF status

The relationship between microvessel density (MVD), lymphovascular density (LVD), and lymphovascular invasion (LVI) in primary cutaneous melanoma (PCM) remains unclear. Given this, a total of 102 PCMs were assessed for MVD (vascular endothelial growth factor receptor 2 and Endocan), LVD (D2-40), and LVI (immunostaining with D2-40/S-100 and hematoxylin and eosin); tumoral S-100A13, vascular endothelial growth factor receptor 2, and Endocan; and BRAF status. LVD was associated with MVD (P = .01). MVD was higher in PCMs with depth greater than or equal to 2 mm and ulceration (P = .04, .05), whereas LVD was higher in PCMs with depth greater than or equal to 2 mm and mitoses (P = .03, .02). After adjusting for MVD and LVD, only ulceration was associated with LVI (P < .02). A BRAF mutation was seen in 30.4% cases, and when present, both LVD and host response (P = .0008 and .04, respectively) were significantly associated with MVD. Immunostaining with S-100A13 was noted in 99% of cases and a significant association noted only with ulceration (P = .05). Immunostaining increased LVI positivity (46.5% versus 4.9% by hematoxylin and eosin, P < .0001). MVD and LVD are not associated with LVI, appear to be closely related with each other, and are associated with select markers of poor prognosticative value. The association between a host response and LVD and MVD in PCMs with a BRAF mutation suggests that they exhibit potential for strategizing immunotherapies.

Mechanisms of tumour vascularization in cutaneous malignant melanoma: clinical implications

Malignant melanoma represents < 10% of all skin cancers but is responsible for the majority of skin-cancer-related deaths. Metastatic melanoma has historically been considered as one of the most therapeutically challenging malignancies. Fortunately, for the first time after decades of basic research and clinical investigation, new drugs have produced major clinical responses. Angiogenesis has been considered an important target for cancer treatment. Initial efforts have focused primarily on targeting endothelial and tumour-related vascular endothelial growth factor signalling. Here, we review different mechanisms of tumour vascularization described in melanoma and discuss the potential clinical implications.

The role of strong hypoxia in tumors after treatment in the outcome of bacteriochlorin-based photodynamic therapy

Blood flow and pO2 changes after vascular-targeted photodynamic therapy (V-PDT) or cellular-targeted PDT (C-PDT) using 5,10,15,20-tetrakis(2,6-difluoro-3-N-methylsulfamoylphenyl) bacteriochlorin (F2BMet) as photosensitizer were investigated in DBA/2 mice with S91 Cloudman mouse melanoma, and correlated with long-term tumor responses. F2BMet generates both singlet oxygen and hydroxyl radicals under near-infrared radiation, which consume oxygen. Partial oxygen pressure was lowered in PDT-treated tumors and this was ascribed both to oxygen consumption during PDT and to fluctuations in oxygen transport after PDT. Similarly, microcirculatory blood flow changed as a result of the disruption of blood vessels by the treatment. A novel noninvasive approach combining electron paramagnetic resonance oximetry and laser Doppler blood perfusion measurements allowed longitudinal monitoring of hypoxia and vascular function changes in the same animals, after PDT. C-PDT induced parallel changes in tumor pO2 and blood flow, i.e., an initial decrease immediately after treatment, followed by a slow increase. In contrast, V-PDT led to a strong and persistent depletion of pO2, although the microcirculatory blood flow increased. Strong hypoxia after V-PDT led to a slight increase in VEGF level 24h after treatment. C-PDT caused a ca. 5-day delay in tumor growth, whereas V-PDT was much more efficient and led to tumor growth inhibition in 90% of animals. The tumors of 44% of mice treated with V-PDT regressed completely and did not reappear for over 1 year. In conclusion, mild and transient hypoxia after C-PDT led to intense pO2 compensatory effects and modest tumor inhibition, but strong and persistent local hypoxia after V-PDT caused tumor growth inhibition.

Differential growth inhibition of cerebral metastases by anti-angiogenic compounds

BACKGROUND

The formation of brain metastases is intrinsically linked to concomitant angiogenesis. The purpose of the present study was to investigate the combined effects of interleukin-12 (IL-12) and EMD121974 on the growth and distribution of melanoma brain metastases since both substances may interact with important steps in the cascade of brain metastases formation.

MATERIALS AND METHODS

Brain metastases were induced by either stereotactic implantation of cells to the brain parenchyma or by injection of the melanoma cells into the internal carotid artery to mimic hematogenous metastatic spread in mice. Naive or IL-12-overexpressing murine K1735 melanoma cells were used either alone or in combination with intraperitoneal anti-integrin treatment using EMD121974.

RESULTS

Solid melanoma metastases were more susceptible to daily low-dose treatment of EMD121974 than multiple hematogenous metastases. Interleukin-12 had a profound effect on both types of brain metastases. After 21 days, a marked reduction of vascularity was observed in both tumor types.

CONCLUSION

The combination of endogenous IL-12 production with integrin blockade resulted in additive effects for murine hematogenous brain metastases but not for focal brain metastases.

Potential use of contrast-enhanced ultrasound (CEUS) in the detection of metastatic superficial lymph nodes in melanoma patients

PURPOSE

Malignant melanoma represents a significant and growing public health burden worldwide. Ultrasonography is the most useful diagnostic modality for regional lymph nodal staging. Because any focal areas of cortical lobulation or thickening-swelling should also be considered as a sign of metastases, we are going to report the usefulness of contrast-enhanced ultrasonography (CEUS) in the differential diagnosis of benign or malignant lymph nodes in patients with malignant melanoma based on blood stream patterns and investigate the diagnostic capability.

PATIENTS AND METHODS

After the excision of cutaneous melanoma with positive excision margins but with negative sentinel lymph node, 540 patients underwent US of superficial lymph nodes. The inclusion criteria for CEUS consisted of both major signs (absence of the echogenic hilus, round shape, and peripheral capsular vascularity) and minor ones (the presence of focal cortical thickening). The diagnostic capability was evaluated by comparing the cytological findings with the enhancement pattern on CEUS. 

RESULTS

US in combination with CEUS correctly classified 534/540 patients. CEUS applied to lymph nodes with focal cortical thickening on grayscale US confirmed great sensitivity (0.98) and specificity (0.99) but above all, it showed a markedly improved accuracy of 0.99. The likelihood ratios confirmed the good performance of the methods used.

CONCLUSION

CEUS increases the diagnostic accuracy of US in the differential diagnosis of benign and malignant LNs but it also allows us, when possible, to avoid unnecessary invasive operations such as LN FNAC. Moreover, CEUS may guide FNAC in the case of focal cortical thickening on the basis of hypoperfusion, with a reduction in the number of false negatives and much earlier detection of nodal metastatic foci.

Correlation between lymphatic vessel density and microvessel density in cutaneous malignant melanoma

BACKGROUND

Malignant melanoma is an aggressive neoplasm, known for its propensity to early metastatic spread, via lymphatic as well as blood vessels. Tumor progression to an aggressive phenotype is associated with angiogenesis. Tumor lymphangiogenesis may represent a marker for assessing the risk of metastasis in the regional lymph nodes.

MATERIALS AND METHODS

We studied the lymphatic vessel density in peritumoral and intratumoral areas compared to overall microvessel density in 12 cases of malignant melanoma of the face. All cases were primary invasive melanomas, with a Clark level of invasion III and IV. Lymphatic vessels were marked with D2-40 murine monoclonal antibody and their density evaluated through hot-spot method by examination on optic microscopy (200×). Overall microvessel density was assessed using the same method, vascular endothelial cells being visualized using CD31 monoclonal antibody. Statistical analysis was made using SPSS 17.0 software package (Pearson correlation test and Student's t-test).

RESULTS

The disposition and aspect of the lymphatic vessels were different in peritumoral and intratumoral areas. Thus, in peritumoral areas lymphatics were generally regular, large, dilated vessels whereas intratumoral lymphatic vessels were smaller, with an irregular lumen. Lymphatic vessel density was generally higher in peritumoral areas. Intratumoral lymphatic vessel density was lower, but significantly correlated to overall microvessel density in these areas. Overall microvessels density was increased in thick cutaneous melanoma. Vessels in the peritumoral areas were larger and more numerous compared to those found in normal tissue. In cases with a dense peritumoral inflammatory infiltrate, we found the highest vascular density. Intratumoral angiogenesis was moderate in most cases, with irregular, smaller or collapsed vessels.

CONCLUSIONS

Evaluation of the lymphatic vessel density may prove to be useful for the prognostic assessment in malignant melanoma, as it may predict the patients with a risk of developing lymph node metastasis.

Tumour vasculogenic mimicry is associated with poor prognosis of human cancer patients: a systemic review and meta-analysis

BACKGROUND

Vasculogenic mimicry (VM) has been reported in various malignant tumours and is known to play an important role in cancer progression and metastasis. However, the impact of VM on the overall survival of human cancer patients remains controversial. The goal of this study was to evaluate whether VM is associated with 5-year survival of human cancer patients.

METHODS

Twenty-two eligible clinical studies with data on both tumour cell-dominant VM and the 5-year survival of 3062 patients involved in 15 types of cancers were pooled in the meta-analysis.

RESULTS

The 5-year overall survival of VM-positive and -negative cancer patients was 31% and 56%, respectively. The relative risk (RR) of the 5-year survival of VM-positive patients was significantly higher than that of VM-negative cases (RR=1.531; 95% confidence interval (CI): 1.357-1.726; P<0.001). Notably, metastatic melanoma patients demonstrated a higher VM rate (45.3%) than patients with primary melanoma (23.1%) and showed worse 5-year survival, suggesting that VM contributes to tumour metastasis and poor prognosis in cancer patients. Subgroup analysis indicated that a poor 5-year survival was significantly associated with eight types of VM-positive malignant tumours, such as lung, colon, liver cancers, sarcomas and melanoma; but was not associated with the seven other types of cancers, such as prostate cancer. Heterogeneity and publication biases were found among the 22 studies, mainly due to the divergent characteristics of cancers and extremely low survival rate in six types of malignant tumours.

CONCLUSION

VM-positive cancer patients show a poor 5-year overall survival compared with VM-negative malignant tumour cases, particularly in metastatic cancer.

Distinct roles of DKK1 and DKK2 in tumor angiogenesis

Tumor angiogenesis is essential for tumor invasive growth and metastasis, and generates abnormal vascular structures unlike developmental neovessel formation. To reduce tumor vascular abnormalities such as leakage and perivascular cell coverage deficiency that limit cancer therapy effectiveness, novel therapeutic approaches focus on vessel normalization. We have previously shown that Dickkopf-1 (DKK1), a Wnt antagonist, inhibits and its homolog DKK2 enhances, angiogenesis in normal tissues. In the present study, we investigated the effects of DKK1 and DKK2 on tumor growth and angiogenesis. Treatment of B16F10 melanoma-bearing mice with adenovirus expressing DKK1 significantly reduced tumor growth but DKK2 increased growth compared with controls. Similar pattern of tumor growth was observed in endothelial-specific DKK1 and DKK2 transgenic mice. Interestingly, tumor vascular density and perfusion were significantly decreased by DKK1 but increased by DKK2. Moreover, coverage of blood vessels by pericytes was reduced by DKK1, while DKK2 increased it. We further observed that DKK1 diminished retinal vessel density and increased avascular area in an in vivo murine model of oxygen-induced retinopathy, whereas DKK2 showed opposite results. These findings demonstrate that DKK1 and DKK2 have differential roles in normalization and functionality of tumor blood vessels, in addition to angiogenesis.

Ultrasonographic staging of cutaneous malignant tumors: an ultrasonographic depth index

The objective of this paper is to assess the role of conventional and high-frequency ultrasound in the evaluation of the depth of cutaneous skin cancer. The study was performed on 46 subjects, divided into 3 categories, according to their skin pathology [basal cell carcinoma (BCC), 18 subjects; superficial spreading melanoma (SSM), 8 subjects; nodular melanoma (NM), 20 subjects]. Conventional and high-frequency ultrasonographic measurements were performed in order to assess the thickness of the tumors and the vascularization degree. We compared the mean values of the tumoral thickness obtained by using ultrasound (ultrasonographic depth index) with the histological depth index, obtained after performing histological sections stained with hematoxylin-eosin, and specific monoclonal antibodies in case of pigmented tumors. We established a correlation index between the histological and ultrasonographic values of the tumoral thickness. We found a strong correlation between the ultrasonographic index (measured by high-frequency sonography) and the histological index for nodular BCC (correlation of 98.4 %), NM subjects (correlation of 98.4 %), and SSM subjects (correlation of 99.4 %). An increase of the blood supply was noticed in nodular lesions only. Ultrasonography allows a very accurate assessment of skin cancer. The ultrasonographic depth index can be considered an objective, non-invasive marker for cutaneous tumors, comparable to the histological one, with a very good sensitivity (98-99 %).

A novel human anti-syndecan-1 antibody inhibits vascular maturation and tumour growth in melanoma

INTRODUCTION

Syndecan-1 is a cell membrane protein that, after its shedding by heparanase enzymes, is accumulated in the extracellular matrix of some tumours, e.g. myeloma and lung carcinoma, where it modulates several key processes of tumourigenesis such as cancer cell proliferation and apoptosis, angiogenesis and metastasis. Few studies have focused on syndecan-1 in malignant melanoma, a tumour for which new therapeutic targets are desperately needed. We aimed to investigate the role of syndecan-1 in melanoma and to evaluate the potential therapeutic efficacy of a novel fully human anti-syndecan-1 recombinant antibody in this deadly disease.

METHODS

The OC-46F2 recombinant antibody was generated by selecting a human antibody phage display library on human melanoma cells and by its expression in mammalian cells. The specific antigen recognised by the antibody was identified by mass spectrometry. Murine models of human melanoma and ovarian carcinoma were used in the pre-clinical in vivo experiments.

RESULTS

The fully human antibody OC-46F2, specific for the extracellular domain of syndecan-1, inhibited vascular maturation and tumour growth in an experimental human melanoma model. The therapeutic efficacy of this antibody was also demonstrated in an experimental ovarian carcinoma model. A co-distribution of syndecan-1 with vascular endothelial growth factor receptor 2 (VEGFR2) observed in the intratumour melanoma microenvironment was absent in the tumours from mice treated with OC-46F2 scFv.

CONCLUSION

These findings highlight the role of syndecan-1 as a potential therapeutic target in melanoma and ovarian carcinoma and provide a new tool able to block vessel maturation, one of the mechanisms that underpin the angiogenic process essential for solid tumour growth.

Imaging of tumor vascularization using fluorescence molecular tomography to monitor arginine deiminase treatment in melanoma

Based on their inability to express argininosuccinate synthetase (ASS), some cancer entities feature the characteristic of L-arginine (Arg) auxotrophy. This inability to intrinsically generate Arg makes them applicable for arginine deiminase (ADI) treatment, an Arg-depleting drug. Arg is also used for the synthesis of endothelial nitric oxide (NO), which mainly confers vasodilatation but is also considered to have a major influence on tumor vascularization. The purpose of this study was to define changes in tumor vasculature in an ADI-treated melanoma xenograft mouse model using the blood pool agent AngioSense 750 and fluorescence molecular tomography (FMT). We used an ASS-negative melanoma xenograft mouse model and subjected it to weekly ADI treatment. Changes in tumor size were measured, and alterations in tumor vasculature were depicted by FMT and CD31 immunohistochemistry (IHC). On ADI treatment and effective antitumor therapy, we observed a drop in NO plasma levels and visualized changes in tumor vascularization with FMT and IHC. ADI treatment in melanoma xenografts has a tumor-reducing effect, which can be noninvasively imaged by quantifying tumor vascularization with FMT and IHC.

Tumor-line specific causes of intertumor heterogeneity in blood supply in human melanoma xenografts

The efficacy of most cancer treatments is strongly influenced by the tumor blood supply. The results of experimental studies using xenografted tumors to evaluate novel cancer treatments may therefore vary considerably depending on the blood supply of the specific tumor model being used. Mechanisms underlying intertumor heterogeneity in the blood supply of xenografted tumors derived from same tumor line are poorly understood, and were investigated here by using intravital microscopy to assess tumor blood supply and vascular morphology in human melanomas growing in dorsal window chambers in BALB/c nu/nu mice. Two melanoma lines, A-07 and R-18, were included in the study. These lines differed substantially in angiogenic profiles. Thus, when the expression of 84 angiogenesis-related genes was investigated with a quantitative PCR array, 25% of these genes showed more than a 10-fold difference in expression. Furthermore, A-07 tumors showed higher vascular density, higher vessel tortuosity, higher vessel diameters, shorter vessel segments, and more chaotic vascular architecture than R-18 tumors. Both lines showed large intertumor heterogeneity in blood supply. In the A-07 line, tumors with low microvascular density, long vessel segment, and high vessel tortuosity showed poor blood supply, whereas in the R-18 line, poor tumor blood supply was associated with low tumor arteriolar diameters. Thus, tumor-line specific causes of intertumor heterogeneity in blood supply were identified in human melanoma xenografts, and these tumor-line specific mechanisms were possibly a result of tumor-line specific angiogenic profiles.

[Overexpression of the receptor tyrosine kinase EphA2 in choroidal melanoma: correlation with vesculogenic mimicry and prognosis]

OBJECTIVE

To study the correlation of EphA2 protein expression with vesculogenic mimicry (VM), clinicopathological characteristics and prognosis in choroidal melanoma (CM).

METHODS

It was a retrospective case series study. Between January 1992 and December 2005, 56 cases of human CM with clinicopathologic data from the Second Hospital of Tianjin Medical University were studied. HE stainings were performed to observe the microcirculation patterns in tumor tissue specimens. VM was found in 26 of the 56 cases using CD31/periodic acid-Schiff (PAS) double staining and transelectron microscopy. All cases were divided into two groups: VM-positive and VM-negative. Immunohistochemical staining was performed on paraffin sections of the 56 cases of CM specimens to investigate the expression of EphA2. According to tumor cells positive rate and staining intensity of the results of evaluation, the specimens were divided into low expression and high expression groups.χ(2)-test and t-test were used to analyzed the enumeration data and measurement data, respectively. Survival analysis was used to further elucidate its correlation with clinicopathological characteristics, VM and prognosis. Cox proportional hazard model was used to analyzed the influence factors of prognosis.

RESULTS

VM channels were found in 26 of the 56 CM cases and VM-negative 30 cases. VM-positivity was related to cell type, tumor size and recurrence and metastasis, and the differences were statistically significant (χ(2) = 4.612, 5.346, 5.213; P = 0.036, 0.021, 0.027). The results showed that EphA2 was up-regulated in the VM-positive group compared with the group of VM-negative group. The positive rates of EphA2 expression in the VM-positive group and VM-negative group were 92.3% (25/26) and 70.0% (21/30), respectively, with a significant difference between the two groups (t = 2.247, P = 0.009). The EphA2 protein was expressed in epithelioid (10/12), mixed (11/15) and spindle (41.40%) cell types, with a significant difference among these histological types (χ(2) = 6.513, P = 0.010). The expression rate of EphA2 protein were significantly higher in large (54.55%, 18/33) than small (45.45%, 15/33) tumors, and the expression of EphA2 in metastatic and recurrence patients (10/11) were significantly higher compared with controls (31.11%, 14/45) (χ(2) = 4.556, 8.211;P = 0.016, 0.005). Kaplan-Meier survival analysis showed the presence of VM resulted in a poor prognosis (t = 9.263, P = 0.000). The Cox proportional hazards model indicated that the EphA2 overexpression and the presence of VM were independent predictors of a poor prognosis (χ(2) = 12.041, P = 0.001). Moreover, there was a significant positive correlation between them (r = 0.412, P < 0.05).

CONCLUSION

The results of this study demonstrate that EphA2 may play a critical role in the formation process of VM in CM, implicating EphA2 as a valuable marker for the prediction of recurrence, metastasis and prognosis in CM patients.