Tumor-induced lymphangiogenesis: a target for cancer therapy?

Ultrasound radiomics-based nomogram to predict lymphovascular invasion in invasive breast cancer: a multicenter, retrospective study

OBJECTIVES

To develop and validate an ultrasound (US) radiomics-based nomogram for the preoperative prediction of the lymphovascular invasion (LVI) status in patients with invasive breast cancer (IBC).

MATERIALS AND METHODS

In this multicentre, retrospective study, 456 consecutive women were enrolled from three institutions. Institutions 1 and 2 were used to train (n = 320) and test (n = 136), and 130 patients from institution 3 were used for external validation. Radiomics features that reflected tumour information were derived from grey-scale US images. The least absolute shrinkage and selection operator and the maximum relevance minimum redundancy (mRMR) algorithm were used for feature selection and radiomics signature (RS) building. US radiomics-based nomogram was constructed by using multivariable logistic regression analysis. Predictive performance was assessed with the receiving operating characteristic curve, discrimination, and calibration.

RESULTS

The nomogram based on clinico-ultrasonic features (menopausal status, US-reported lymph node status, posterior echo features) and RS yielded an optimal AUC of 0.88 (95% confidence interval [CI], 0.84-0.91), 0.89 (95% CI, 0.84-0.94) and 0.95 (95% CI, 0.92-0.99) in the training, internal and external validation cohort. The nomogram outperformed the clinico-ultrasonic and RS model (p < 0.05). The nomogram performed favourable discrimination (C-index, 0.88; 95% CI: 0.84-0.91) and was confirmed in the validation (0.88 for internal, 0.95 for external) cohorts. The calibration and decision curve demonstrated the nomogram showed good calibration and was clinically useful.

CONCLUSIONS

The radiomics nomogram incorporated in the RS and US and the clinical findings exhibited favourable preoperative individualised prediction of LVI.

CLINICAL RELEVANCE STATEMENT

The US radiomics-based nomogram incorporating menopausal status, posterior echo features, US reported-ALN status, and radiomics signature has the potential to predict lymphovascular invasion in patients with invasive breast cancer.

KEY POINTS

• The clinico-ultrsonic model of menopausal status, posterior echo features, and US-reported ALN status achieved a better predictive efficacy for LVI than either of them alone. • The radiomics nomogram showed optimal prediction in predicting LVI from patients with IBC (ROC, 0.88 and 0.89 in the training and validation sets). • A nomogram demonstrated favourable performance (area under the receiver operating characteristic curve, 0.95) and well calibration (C-index, 0.95) in an independent validation cohort (n = 130).

Drug transport modeling in solid tumors: A computational exploration of spatial heterogeneity of biophysical properties

Inadequate uptake of therapeutic agents by tumor cells is still a major barrier in clinical cancer therapy. Mathematical modeling is a powerful tool to describe and investigate the transport phenomena involved. However, current models for interstitial flow and drug delivery in solid tumors have not yet embedded the existing heterogeneity of tumor biomechanical properties. The purpose of this study is to introduce a novel and more realistic methodology for computational models of solid tumor perfusion and drug delivery accounting for these regional heterogeneities as well as lymphatic drainage effects. Several tumor geometries were studied using an advanced computational fluid dynamics (CFD) modeling approach of intratumor interstitial fluid flow and drug transport. Hereby, the following novelties were implemented: (i) the heterogeneity of tumor-specific hydraulic conductivity and capillary permeability; (ii) the effect of lymphatic drainage on interstitial fluid flow and drug penetration. Tumor size and shape both have a crucial role on the interstitial fluid flow regime as well as drug transport illustrating a direct correlation with interstitial fluid pressure (IFP) and an inverse correlation with drug penetration, except for large tumors having a diameter larger than 50 mm. The results also suggest that the interstitial fluid flow and drug penetration in small tumors depend on tumor shape. A parameter study on the necrotic core size illustrated that the core effect (i.e. fluid flow and drug penetration alteration) was only profound in small tumors. Interestingly, the impact of a necrotic core on drug penetration differs depending on the tumor shape from having no effect in ideally spherical tumors to a clear effect in elliptical tumors with a necrotic core. A realistic presence of lymphatic vessels only slightly affected tumor perfusion, having no substantial effect on drug delivery. In conclusion, our findings illustrated that our novel parametric CFD modeling strategy in combination with accurate profiling of heterogeneous tumor biophysical properties can provide a powerful tool for better insights into tumor perfusion and drug transport, enabling effective therapy planning.

IFN-γ-dependent tumor-antigen cross-presentation by lymphatic endothelial cells promotes their killing by T cells and inhibits metastasis

Tumor-associated lymphatic vessels promote metastasis and regulate antitumor immune responses. Here, we assessed the impact of cytotoxic T cells on the local lymphatic vasculature and concomitant tumor dissemination during an antitumor response. Interferon-γ (IFN-γ) released by effector T cells enhanced the expression of immunosuppressive markers by tumor-associated lymphatic endothelial cells (LECs). However, at higher effector T cell densities within the tumor, T cell-based immunotherapies induced LEC apoptosis and decreased tumor lymphatic vessel density. As a consequence, lymphatic flow was impaired, and lymph node metastasis was reduced. Mechanistically, T cell-mediated tumor cell death induced the release of tumor antigens and cross-presentation by tumor LECs, resulting in antigen-specific LEC killing by T cells. When LECs lacked the IFN-γ receptor expression, LEC killing was abrogated, indicating that IFN-γ is indispensable for reducing tumor-associated lymphatic vessel density and drainage. This study provides insight into how cytotoxic T cells modulate tumor lymphatic vessels and may help to improve immunotherapeutic protocols.

BACH family members regulate angiogenesis and lymphangiogenesis by modulating VEGFC expression

Angiogenesis and lymphangiogenesis are key processes during embryogenesis as well as under physiological and pathological conditions. Vascular endothelial growth factor C (VEGFC), the ligand for both VEGFR2 and VEGFR3, is a central lymphangiogenic regulator that also drives angiogenesis. Here, we report that members of the highly conserved BACH (BTB and CNC homology) family of transcription factors regulate VEGFC expression, through direct binding to its promoter. Accordingly, down-regulation of bach2a hinders blood vessel formation and impairs lymphatic sprouting in a Vegfc-dependent manner during zebrafish embryonic development. In contrast, BACH1 overexpression enhances intratumoral blood vessel density and peritumoral lymphatic vessel diameter in ovarian and lung mouse tumor models. The effects on the vascular compartment correlate spatially and temporally with BACH1 transcriptional regulation of VEGFC expression. Altogether, our results uncover a novel role for the BACH/VEGFC signaling axis in lymphatic formation during embryogenesis and cancer, providing a novel potential target for therapeutic interventions.

Primary Preclinical and Clinical Evaluation of 68Ga-DOTA-TMVP1 as a Novel VEGFR-3 PET Imaging Radiotracer in Gynecological Cancer

PURPOSE

Tumor periphery and lymph nodes of tumor-induced lymphangiogenesis often abundantly express VEGFR-3. In our previous study, we identified a 5-amino acid peptide named TMVP1, which binds specifically to VEGFR-3. The objective of this study was to develop a novel ⁶⁸Ga-labeled TMVP1 for VEGFR-3 PET imaging and to investigate its safety, biodistribution, and tumor-localizing efficacy in xenograft tumor models and a small cohort of patients with recurrent ovarian and cervical cancer.

EXPERIMENTAL DESIGN

The DOTA-conjugated TMVP1 peptide was labeled with radionuclide ⁶⁸Ga. SPR and saturation binding assays were used for the receptor-binding studies. Gynecologic xenograft tumors were employed for small-animal PET imaging and biodistribution of ⁶⁸Ga-DOTA-TMVP1 in vivo. In the clinical study, 5 healthy volunteers and 8 patients with gynecologic cancer underwent whole-body PET/CT after being injected with ⁶⁸Ga-DOTA-TMVP1.

RESULTS

DOTA-TMVP1 was successfully labeled with ⁶⁸Ga. LECs showed higher binding capacity with ⁶⁸Ga-DOTA-TMVP1 than LEC(shVEGFR-3) and human umbilical vein endothelial cells. In mice with subcutaneous C33-A and SKOV-3 xenografts, the tracer was rapidly eliminated through the kidney to the bladder, and the small-animal PET/CT helped to clearly visualize the tumors. In patients with recurrent ovarian cancer and cervical cancer, tracer accumulation well above the background level was demonstrated in most identified sites of disease; especially with recurrent endodermal sinus tumors, the diagnostic value of ⁶⁸Ga-DOTA-TMVP1 was comparable with that of ¹⁸F-FDG PET/CT.

CONCLUSIONS

⁶⁸Ga-DOTA-TMVP1 is a potential PET tracer for imaging VEGFR-3 with favorable pharmacokinetics.

Rapamycin suppresses angiogenesis and lymphangiogenesis in melanoma by downregulating VEGF-A/VEGFR-2 and VEGF-C/VEGFR-3 expression

Background: Cutaneous melanoma is a highly malignant tumor which tends to metastasize in the early stage and leads to poor prognosis. Hematogenous and lymphatic metastasis are common in the dissemination of melanoma. Rapamycin, an mTOR inhibitor, was reported to have anti-angiogenic and anti-lymphangiogenic properties.

Aim: The aim of this study was to investigate if rapamycin can inhibit the formation of blood vessels and lymphatic vessels in melanoma.

Methods: A melanoma xenograft model was generated by subcutaneously transplanting A375 human melanoma cells into the back of immunodeficient mice. Two weeks after cell transplantation, rapamycin was injected intraperitoneally every other day seven times. Then, tumors were harvested. Hematoxylin-eosin (H-E) staining, immunohistochemical staining, Western blot, and quantitative PCR were performed to observe the pathological structure of the tumor, the distribution of blood vessels and lymphatic vessels, and the expression of mTOR signal pathway, VEGF-A/VEGFR-2, and VEGF-C/VEGFR-3.

Results: The results showed that CD34(+) blood vessels and LYVE-1(+) lymphatic vessels decreased in the peritumor and intratumor region in rapamycin-treated tumors. Expression of p-4EBP1 and p-S6K1 proteins was downregulated. Expression of both proteins and mRNAs of VEGF-A/VEGFR-2 and VEGF-C/VEGFR-3 was downregulated.

Conclusion: In conclusion, rapamycin suppresses angiogenesis and lymphangiogenesis in melanoma by blocking the mTOR signal pathway and subsequently downregulating the expression of VEGF-A/VEGFR-2 and VEGF-C/VEGFR-3. Therefore, targeted therapy via mTOR signal pathway may control the hematogenous and lymphatic metastasis of melanoma, and even prolong patients’ survival time.

Point your SmartPhone at the code above. If you have a QR code reader the video abstract will appear. Or use:

https://youtu.be/Q1fo3NUeLpY

Lymphangiogenesis, lymphatic systemomics, and cancer: context, advances and unanswered questions

Ever since it was discovered that endothelial cells line lymphatic vessels, investigators have been working on unraveling the mechanisms that control the growth of this distinctive endothelium and its role in normal physiology and human disease. Recent technological advances have ushered in a new era of "omics" research on the lymphatic system. Research on the genome, transcriptome, proteome, and metabolome of lymphatics has increased our understanding of the biology of the lymphatic vasculature. Here, we introduce the context-lymphatic "systemomics," then briefly review some of the latest advances in research on tumor-associated lymphatic vessels highlighting several "omic" studies that have shed light on mechanisms controlling the growth and function of tumor-associated lymphatic vessels. We conclude by returning, with unanswered questions, to the larger context of cancer and the lymphatic system as a vasculature, circulation, route of entry and transport, and control center of the immune network.

Effects of fatty acid synthase inhibitors on lymphatic vessels: an in vitro and in vivo study in a melanoma model

Fatty acid synthase (FASN) is responsible for the endogenous production of fatty acids from acetyl-CoA and malonyl-CoA. Its overexpression is associated with poor prognosis in human cancers including melanomas. Our group has previously shown that the inhibition of FASN with orlistat reduces spontaneous lymphatic metastasis in experimental B16-F10 melanomas, which is a consequence, at least in part, of the reduction of proliferation and induction of apoptosis. Here, we sought to investigate the effects of pharmacological FASN inhibition on lymphatic vessels by using cell culture and mouse models. The effects of FASN inhibitors cerulenin and orlistat on the proliferation, apoptosis, and migration of human lymphatic endothelial cells (HDLEC) were evaluated with in vitro models. The lymphatic outgrowth was evaluated by using a murine ex vivo assay. B16-F10 melanomas and surgical wounds were produced in the ears of C57Bl/6 and Balb-C mice, respectively, and their peripheral lymphatic vessels evaluated by fluorescent microlymphangiography. The secretion of vascular endothelial growth factor C and D (VEGF-C and -D) by melanoma cells was evaluated by ELISA and conditioned media used to study in vitro lymphangiogenesis. Here, we show that cerulenin and orlistat decrease the viability, proliferation, and migration of HDLEC cells. The volume of lymph node metastases from B16-F10 experimental melanomas was reduced by 39% in orlistat-treated animals as well as the expression of VEGF-C in these tissues. In addition, lymphatic vessels from orlistat-treated mice drained more efficiently the injected FITC-dextran. Orlistat and cerulenin reduced VEGF-C secretion and, increase production of VEGF-D by B16-F10 and SK-Mel-25 melanoma cells. Finally, reduced lymphatic cell extensions, were observed following the treatment with conditioned medium from cerulenin- and orlistat-treated B16-F10 cells. Altogether, our results show that FASN inhibitors have anti-metastatic effects by acting on lymphatic endothelium and melanoma cells regardless the increase of lymphatic permeability promoted by orlistat.

The role of lymphangiogenesis and angiogenesis in tumor metastasis

BACKGROUND

Metastasis is the main cause of mortality in cancer patients. Two major routes of cancer cell spread are currently being recognized: dissemination via blood vessels (hematogenous spread) and dissemination via the lymphatic system (lymphogenous spread). Here, our current knowledge on the role of both blood and lymphatic vessels in cancer cell metastasis is summarized. In addition, I will discuss why cancer cells select one or both of the two routes to disseminate and I will provide a short description of the passive and active models of intravasation. Finally, lymphatic vessel density (LVD), blood vessel density (BVD), interstitial fluid pressure (IFP) and tumor hypoxia, as well as regional lymph node metastasis and the recently discovered primo vascular system (PVS) will be highlighted as important factors influencing tumor cell motility and spread and, ultimately, clinical outcome.

CONCLUSIONS

Lymphangiogenesis and angiogenesis are important phenomena involved in the spread of cancer cells and they are associated with a poor prognosis. It is anticipated that new discoveries and advancing knowledge on these phenomena will allow an improvement in the treatment of cancer patients.

Tumor-associated Lymphatic Endothelial Cells Promote Lymphatic Metastasis By Highly Expressing and Secreting SEMA4C

PURPOSE

Lymphatic vessels are mainly regarded as passive conduits for the dissemination of cancer cells. In this study, we investigate whether and how the tumor-associated lymphatic vessels may play an active role in tumor metastasis.

EXPERIMENTAL DESIGN

In situ laser capture microdissection of lymphatic vessels followed by cDNA microarray analysis was used to determine the expression profiling of lymphatic endothelial cells (LEC). Gene expression levels and activity of signaling pathways were measured by real-time RT-PCR, ELISA, or immunoblotting. Lymphangiogenesis was assessed by IHC. Lymph node metastasis was measured using fluorescence imaging. The effects of SEMA4C on lymphangiogenesis in vitro were evaluated using migration assay and tube-formation assay of LECs.

RESULTS

Tumor-associated LECs are molecularly and functionally different from their normal counterparts. In addition to expressing high levels of membrane-bound SEMA4C, tumor-associated LECs also produced soluble SEMA4C (sSEMA4C). Increased serum sSEMA4C was detected in patients with breast cancer and cervical cancer. Patients with metastasis had much higher levels of serum sSEMA4C. sSEMA4C promoted lymphangiogenesis by activating PlexinB2-ERBB2 signaling in LECs, and promoted the proliferation and migration of tumor cells by activating PlexinB2-MET signaling, thus promoting lymphatic metastasis. Although the SEMA4C signaling pathways differ between LECs and tumor cells, RHOA activation was necessary for the effects of SEMA4C in both types of cells.

CONCLUSIONS

Tumor-associated LECs produce sSEMA4C to promote lymphatic metastasis of tumors. Our results suggest that SEMA4C and RHOA might be potential therapeutic targets, and that higher serum sSEMA4C could be a marker for breast cancer and cervical cancer. Clin Cancer Res; 23(1); 214-24. ©2016 AACR.

Vasohibin-1 suppresses colon cancer

Vasohibin-1 (VASH1) is an endogenous angiogenesis inhibitor.However, the clinical relevance of VASH1 in colon cancer and its regulations on cancer angiogenesis and cancer cell biological characteristics are still unknown. Here we showed that stromal VASH1 levels were negatively correlated with tumor size, advanced clinical stage and distant metastases in colon cancer patients. Overexpression of VASH1 in colon cancer cells induced apoptosis and senescence, inhibiting cancer cell growth and colony formation in vitro and tumor growth in vivo. In addition, knockdown of VASH1 in cancer cells promoted cell growth, adhesion and migration in vitro, and enhanced tumorigenesis and metastasis in vivo.

Tumor Interstitial Fluid Formation, Characterization, and Clinical Implications

The interstitium, situated between the blood and lymph vessels and the cells, consists of a solid or matrix phase and a fluid phase representing the tissue microenvironment. In the present review, we focus on the interstitial fluid phase of solid tumors, the tumor interstitial fluid (TIF), i.e., the fluid bathing the tumor and stroma cells, also including immune cells. This is a component of the internal milieu of a solid tumor that has attracted regained attention. Access to this space may provide important insight into tumor development and therapy response. TIF is formed by transcapillary filtration, and since this fluid is not readily available we discuss available techniques for TIF isolation, results from subsequent characterization and implications of recent findings with respect to fluid filtration and uptake of macromolecular therapeutic agents. There appear to be local gradients in signaling substances from neoplastic tissue to plasma that may provide new understanding of tumor biology. The development of sensitive proteomic technologies has made TIF a valuable source for tumor specific proteins and biomarker candidates. Potential biomarkers will appear locally in high concentrations in tumors and may eventually be found diluted in the plasma. Access to TIF that reliably reflects the local tumor microenvironment enables identification of substances that can be used in early detection and monitoring of disease.

TBL1XR1 promotes lymphangiogenesis and lymphatic metastasis in esophageal squamous cell carcinoma

OBJECTIVE

Transducin (β)-like 1 X-linked receptor 1 (TBL1XR1) plays an important role in controlling the precisely regulated switch between gene repression and gene activation in transcriptional regulation. We investigated its biological function and clinical significance in esophageal squamous cell carcinoma (ESCC).

DESIGN

Immunoblotting and immunochemistry were used to determine TBL1XR1 expression in ESCC cell lines, ESCC clinical tissues and 230 clinicopathologically characterised ESCC specimens. The role of TBL1XR1 in lymphangiogenesis and lymphatic metastasis was examined by tube formation, cell invasion and wound-healing assays in vitro, and by a popliteal lymph node metastasis model in vivo. The molecular mechanism by which TBL1XR1 upregulates vascular endothelial growth factor C (VEGF-C) expression was explored using real-time PCR, ELISA, luciferase reporter assay and chromatin immunoprecipitation.

RESULTS

TBL1XR1 expression was significantly upregulated in ESCC, positively correlated with disease stage and patient survival, and identified as an independent prognostic factor for patient outcome. We found that TBL1XR1 overexpression promoted lymphangiogenesis and lymphatic metastasis in ESCC in vitro and in vivo, whereas TBL1XR1 silencing had the converse effect. We demonstrated that TBL1XR1 induced VEGF-C expression by binding to the VEGF-C promoter. We confirmed the correlation between TBL1XR1 and VEGF-C expression in a large cohort of clinical ESCC samples and through analysis of published datasets in gastric, colorectal and breast cancer.

CONCLUSIONS

Our results demonstrated that TBL1XR1 induced lymphangiogenesis and lymphatic metastasis in ESCC via upregulation of VEGF-C, and may represent a novel prognostic biomarker and therapeutic target for patients with ESCC.

Antilymphangiogenic therapy to promote transplant survival and to reduce cancer metastasis: what can we learn from the eye?

The lymphatic vasculature is - amongst other tasks - essentially involved in inflammation, (auto)immunity, graft rejection and cancer metastasis. The eye is mainly devoid of lymphatic vessels except for its adnexa, the conjunctiva and the limbus. However, several pathologic conditions can result in the secondary ingrowth of lymphatic vessels into physiologically alymphatic parts of the eye such as the cornea or the inner eye. Therefore, the cornea has served as an excellent in vivo model system to study lymphangiogenesis, and findings from such studies have substantially contributed to the understanding of central principles of lymphangiogenesis also with relevance outside the eye. Grafting experiments at the cornea have been extensively used to analyze the role of lymphangiogenesis in transplant immunology. In this regard, we recently demonstrated the crucial role of lymphatic vessels in mediating corneal allograft rejection and could show that antilymphangiogenic therapy increases graft survival. In the field of cancer research, we recently detected tumor-associated lymphangiogenesis in the most common malignant tumors of the eye, such as conjunctival carcinoma and melanoma, and ciliochoroidal melanoma with extraocular extension. These neolymphatics correlate with an increased risk of local recurrence, metastasis and tumor related death, and may offer potential therapeutic targets for the treatment of these tumors. This review will focus on corneal and tumor-associated ocular lymphangiogenesis. First, we will describe common experimentally used corneal lymphangiogenesis models and will recapitulate recent findings regarding the involvement of lymphatic vessels in corneal diseases and transplant immunology. The second part of this article will summarize findings about the participation of tumor-associated lymphangiogenesis in ocular malignancies and their implications for the development of future therapeutic strategies.

Microenvironment of tumor-draining lymph nodes: opportunities for liposome-based targeted therapy

The World Health Organization (WHO) recently reported that the total number of global cancer cases in 2013 reached 14 million, a 10% rise since 2008, while the total number of cancer deaths reached 8.2 million, a 5.2% increase since 2008. Metastasis is the major cause of death from cancer, accounting for 90% of all cancer related deaths. Tumor-draining lymph nodes (TDLN), the sentinel nodes, are the first organs of metastasis in several types of cancers. The extent of metastasis in the TDLN is often used in disease staging and prognosis evaluation in cancer patients. Here, we describe the microenvironment of the TDLN and review the recent literature on liposome-based therapies directed to immune cells within the TDLN with the intent to target cancer cells.

Head and neck squamous cell carcinoma lymphatic spread and survival: Relevance of vascular endothelial growth factor family for tumor evaluation

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is primarily a locoregional disease in which the cervical lymph nodes are the chief site of metastasis. The purpose of this study was to examine the relationship between lymphangiogenesis and clinicopathological aspects of HNSCC and its metastasis.

METHODS

Fifty-two patients with HNSCC and metastatic lymph nodes from 21 of these subjects were analyzed by immunohistochemistry.

RESULTS

The HNSCC samples were predominantly negative for vascular endothelial growth factor (VEGF)-C, VEGF-D, and vascular endothelial growth factor receptor (VEGFR)3. There was an association between the density of lymph vessels (measured by D2-40 staining) in the lymph nodes and advanced-stage tumors. There was no link between the expression of these proteins and survival rates.

CONCLUSION

Although lymphatic spread is a significant event in the progression of HNSCC, the expression of VEGF-C, VEGF-D, and VEGFR3 does not correlate with clinicopathological characteristics, suggesting that other signaling pathways mediate lymphangiogenesis in HNSCC.

The FAK scaffold inhibitor C4 disrupts FAK-VEGFR-3 signaling and inhibits pancreatic cancer growth

Even with successful surgical resection and perioperative chemotherapy and radiation, pancreatic ductal adenocarcinoma (PDA) has a high incidence of recurrence. Tumor cell survival depends on activation of signaling pathways that suppress the apoptotic stimuli of invasion and metastasis. Focal adhesion kinase (FAK) is a critical signaling molecule that has been implicated in tumor cell survival, invasion and metastasis. We have previously shown that FAK and vascular endothelial growth factor receptor 3 (VEGFR-3) are overexpressed in cancer cells and physically interact to confer a significant survival advantage. We subsequently identified a novel small molecule inhibitor C4 that targeted the VEGFR-3-FAK site of interaction. In this study, we have shown that C4 disrupted the FAK-VEGFR-3 complexes in PDA cells. C4 treatment caused dose-dependent dephosphorylation and inactivation of the VEGFR-3 and FAK, reduction in cell viability and proliferation, cell cycle arrest and apoptosis in PDA cells. C4 increased the sensitivity of tumor cells to gemcitabine chemotherapy in vitro that lead to apoptosis at nanomolar concentrations of both drugs. C4 reduced tumor growth in vivo in subcutaneous and orthotopic murine models of PDA. The drug alone at low dose, decreased tumor growth; however, concomitant administration with low dose of gemcitabine had significant synergistic effect and led to 70% tumor reduction. Combination of C4 with gemcitabine had a prolonged cytostatic effect on tumor growth after treatment withdrawal. Finally, we report an anecdotal case of stage IV pancreatic cancer treated with gemcitabine in combination with C4 that showed a significant clinical response in primary tumor and complete clinical response in liver metastasis over an eight month period. Taken together, these results demonstrate that targeting the scaffolding function of FAK with a small-molecule FAK-VEGFR-3 inhibitor can be an effective therapeutic strategy against PDA.

[Lymphatic extension and lymphangiogenesis in non-small cell lung cancer]

Lymph node metastasis is a major adverse prognostic factor of malignant tumors, including non-small cell lung carcinoma (NSCLC). However the characterization of tumor associated lymphatic vessels and lymphangiogenic mediators in NSCLC are recent and their prognostic role is debated. Lymphatic vascular invasion (LVI) appears like a robust adverse prognostic factor when reported in NSCLC. This parameter should be better standardized and could be of use in adjuvant therapy indications. Moreover, anti-lymphangiogenesis therapies are currently under investigation and may become part of the anti-cancer strategy.

Microarray gene expression analysis of tumorigenesis and regional lymph node metastasis in laryngeal squamous cell carcinoma

BACKGROUND

Laryngeal squamous cell carcinoma (LSCC) is the most common type in head and neck squamous cell carcinoma (HNSCC), and the development and progression of LSCC are multistep processes accompanied by changes of molecular biology.

OBJECTIVE

The purpose of this study was to investigate the molecular basis of tumorigenesis and regional lymph node metastasis in LSCC, and provide a set of genes that may be useful for the development of novel diagnostic markers and/or more effective therapeutic strategies.

METHODS

A total number of 10 patients who underwent surgery for primary laryngeal squamous cell carcinoma were recruited for microarray analysis. LSCC tissues compared with corresponding adjacent non-neoplastic tissues were analysed by Illumina mRNA microarrays, and LSCC tissues with regional lymph node metastasis and LSCC tissues without regional lymph node metastasis were analyzed in the same manner. The most frequently differently expressed genes screened by microarrays were also validated by qRT-PCR in another 42 patients diagnosed for LSCC.

RESULTS

Analysed by Illumina mRNA microarrays, there were 361 genes significantly related to tumorigenesis while 246 genes significantly related to regional lymph node metastasis in LSCC. We found that the six genes (CDK1, CDK2, CDK4, MCM2, MCM3, MCM4) were most frequently differently expressed functional genes related to tumorigenesis while eIF3a and RPN2 were most frequently differently expressed functional genes related to regional lymph node metastasis in LSCC. The expressions of these genes were also validated by qRT-PCR.

CONCLUSIONS

The research revealed a gene expression signature of tumorigenesis and regional lymph node metastasis in laryngeal squamous cell carcinoma. Of the total, the deregulation of several genes (CDK1, CDK2, CDK4, MCM2, MCM3, MCM4, EIF3a and RPN2) were potentially associated with disease development and progression. The result will contribute to the understanding of the molecular basis of LSCC and help to improve diagnosis and treatment.

Interstitial fluid-a reflection of the tumor cell microenvironment and secretome

The interstitium or interstitial space describes the space outside the blood and lymphatic vessels. It contains two phases; the interstitial fluid (IF) and the extracellular matrix. In this review we focus on the interstitial fluid phase, which is the physical and biochemical microenvironment of the cells, and more specifically that of tumors. IF is created by transcapillary filtration and cleared by lymphatic vessels, and contains substances that are either produced and secreted locally, thus denoted secretome, or brought to the organ by the circulation. The structure of the interstitium is discussed briefly and moreover techniques for IF isolation focusing on those that are relevant for studies of the secretome. Accumulated data show that tumor IF is hypoxic and acidic compared with subcutaneous IF and plasma, and that there are gradients between IF and plasma giving information on where substances are produced and thereby reflecting the local microenvironment. We review recent data on the origin of tissue specific substances, challenges related to isolating a representative secretome and the use of this as a substrate for biomarker identification. Finally we perform a comparative analysis across human tumor types and techniques and show that there is great variation in the results obtained that may at least partially be due to the isolation method used. We conclude that when care is taken in isolation of substrate, analysis of the secretome may give valuable biological insight and result in identification of biomarker candidates. This article is part of a Special Issue entitled: An Updated Secretome.

Novel anti(lymph)angiogenic treatment strategies for corneal and ocular surface diseases

The cornea is one of the few tissues which actively maintain an avascular state, i.e. the absence of blood and lymphatic vessels (corneal [lymph]angiogenic privilege). Nonetheless do several diseases interfere with this privilege and cause pathologic corneal hem- and lymphangiogenesis. The ingrowths of pathologic blood and lymphatic vessels into the cornea not only reduce transparency and thereby visual acuity up to blindness, but also significantly increases the rate of graft rejections after subsequent corneal transplantation. Therefore great interest exists in new strategies to target pathologic corneal (lymph)angiogenesis to promote graft survival. This review gives an overview on the vascular anatomy of the normal ocular surface, on the molecular mechanisms contributing to the corneal (lymph)angiogenic privilege and on the cellular and molecular mechanisms occurring during pathological neovascularization of the cornea. In addition we summarize the current preclinical and clinical evidence for three novel treatment strategies against ocular surface diseases based on targeting pathologic (lymph)angiogenesis: (a) modulation of the immune responses after (corneal) transplantation by targeting pathologic (lymph)angiogenesis prior to and after transplantation, (b) novel concepts against metastasis and recurrence of ocular surface tumors such as malignant melanoma of the conjunctiva by anti(lymph)angiogenic therapy and (c) new ideas on how to target ocular surface inflammatory diseases such as dry eye by targeting conjunctival and corneal lymphatic vessels. Based on compelling preclinical evidence and early data from clinical trials the novel therapeutic concepts of promoting graft survival, inhibiting tumor metastasis and dampening ocular surface inflammation and dry eye disease by targeting (lymph)angiogenesis are on their way to translation into the clinic.

Screening of peptides bound to breast cancer stem cell specific surface marker CD44 by phage display

CD44, a cancer-associated membrane glycoprotein involved in cell adhesion and tumor progression, has been implicated as a cancer stem cell antigen in several cancers including breast cancer. If the detection sensitivity of CD44 as an early marker for cancer could be improved, this would have important clinical applications. As compared with early stage treatments of other kinds of cancer, treatment of breast cancer is more likely to results in positive outcomes, so this early detection is crucial. Therefore, CD44 is a potential diagnostic target for cancer detection. Herein, we have used a peptide library to screen novel diverse peptides that bind to CD44 with high affinity and characterized the specific binding of these peptides. Our work provides a basis to develop novel diagnostic peptides which may replace antibodies as CD44 detection probes.

Lymphangiogenesis and cancer

Historically, lymphatic vessels were considered passive participants in tumor metastasis by simply providing channels for tumor cells to transit to draining lymph nodes. The discovery of several key lymphatic-specific molecular markers and an increased availability of in vitro and in vivo experimental systems to study lymphatic biology have however highlighted a much more complex, active role for the lymphatic vasculature in metastatic tumor spread. This review will briefly describe the lymphatic system and lymphangiogenesis and then focus on the role of the lymphatic system in cancer metastasis. The progression of our understanding from the lymphatic system as a somewhat passive conduit for metastasis to an active participant in metastatic tumor dissemination, regulated by a complex array of lymphangiogenic factors, chemokines, and immune cell subsets, will be described.

VEGFR-3 is expressed on megakaryocyte precursors in the murine bone marrow and plays a regulatory role in megakaryopoiesis

VEGFR-3 is a transmembrane receptor tyrosine kinase that is activated by its ligands VEGF-C and VEGF-D. Although VEGFR-3 has been linked primarily to the regulation of lymphangiogenesis, in the present study, we demonstrate a role for VEGFR-3 in megakaryopoiesis. Using a human erythroleukemia cell line and primary murine BM cells, we show that VEGFR-3 is expressed on megakaryocytic progenitor cells through to the promegakaryoblast stage. Functionally, specific activation of VEGFR-3 impaired the transition to polyploidy of CD41+ cells in primary BM cultures. Blockade of VEGFR-3 promoted endoreplication consistently. In vivo, long-term activation or blockade of VEGFR-3 did not affect steady-state murine megakaryopoiesis or platelet counts significantly. However, activation of VEGFR-3 in sublethally irradiated mice resulted in significantly elevated numbers of CD41+ cells in the BM and a significant increase in diploid CD41+ cells, whereas the number of polyploid CD41+ cells was reduced significantly. Moreover, activation of VEGFR-3 increased platelet counts in thrombopoietin-treated mice significantly and modulated 5-fluorouracil-induced thrombocytosis strongly, suggesting a regulatory role for VEGFR-3 in megakaryopoiesis.

The role of targeted therapy and biomarkers in breast cancer treatment

Breast cancer is the most prevalent life-threatening cancer in women and the second leading cause of cancer associated deaths. Consequently, optimizing breast cancer therapy to increase cure rates in early stage disease and improve life expectancy and palliation for patients with metastasis is a critical need and major area of research in medical oncology. This article focuses on the development of personalized therapy in breast cancer though the use of targeted therapies and their associated biomarkers. Topics reviewed include the historic advances in targeting the HER2 receptor and the current avenues being studied to circumvent resistance; new developments in the management of triple negative and metastatic breast cancer; and the challenges and pitfalls associated with targeting angiogenesis. Using these as examples, many of the innovations and challenges in the treatment of women with breast cancer are explored.

Angiogenesis and lymphangiogenesis as prognostic factors after therapy in patients with cervical cancer

AIM OF THE STUDY

This retrospective study attempts to evaluate the influence of serum vascular endothelial growth factor C (VEGF-C), microvessel density (MVD) and lymphatic vessel density (LMVD) on the result of tumour treatment in women with cervical cancer.

MATERIAL AND METHODS

The research was carried out in a group of 58 patients scheduled for brachytherapy for cervical cancer. All women were patients of the Department and University Hospital of Oncology and Brachytherapy, Collegium Medicum in Bydgoszcz of Nicolaus Copernicus University in Toruń. VEGF-C was determined by means of a quantitative sandwich enzyme immunoassay using a human antibody VEGF-C ELISA produced by Bender MedSystem, enzyme-linked immunosorbent detecting the activity of human VEGF-C in body fluids. The measure for the intensity of angiogenesis and lymphangiogenesis in immunohistochemical reactions is the number of blood vessels within the tumour. Statistical analysis was done using Statistica 6.0 software (StatSoft, Inc. 2001). The Cox proportional hazards model was used for univariate and multivariate analyses. Univariate analysis of overall survival was performed as outlined by Kaplan and Meier. In all statistical analyses p < 0.05 (marked red) was taken as significant.

RESULTS

In 51 patients who showed up for follow-up examination, the influence of the factors of angiogenesis, lymphangiogenesis, patients' age and the level of haemoglobin at the end of treatment were assessed. Selected variables, such as patients' age, lymph vessel density (LMVD), microvessel density (MVD) and the level of haemoglobin (Hb) before treatment were analysed by means of Cox logical regression as potential prognostic factors for lymph node invasion. The observed differences were statistically significant for haemoglobin level before treatment and the platelet number after treatment. The study revealed the following prognostic factors: lymph node status, FIGO stage, and kind of treatment. No statistically significant influence of angiogenic and lymphangiogenic factors on the prognosis was found.

CONCLUSION

Angiogenic and lymphangiogenic factors have no value in predicting response to radiotherapy in cervical cancer patients.

Tumor lymphangiogenesis as a potential therapeutic target

Metastasis the spread of cancer cells to distant organs, is the main cause of death for cancer patients. Metastasis is often mediated by lymphatic vessels that invade the primary tumor, and an early sign of metastasis is the presence of cancer cells in the regional lymph node (the first lymph node colonized by metastasizing cancer cells from a primary tumor). Understanding the interplay between tumorigenesis and lymphangiogenesis (the formation of lymphatic vessels associated with tumor growth) will provide us with new insights into mechanisms that modulate metastatic spread. In the long term, these insights will help to define new molecular targets that could be used to block lymphatic vessel-mediated metastasis and increase patient survival. Here, we review the molecular mechanisms of embryonic lymphangiogenesis and those that are recapitulated in tumor lymphangiogenesis, with a view to identifying potential targets for therapies designed to suppress tumor lymphangiogenesis and hence metastasis.

Interaction of tumor cells and lymphatic vessels in cancer progression

Metastatic spread of cancer through the lymphatic system affects hundreds of thousands of patients yearly. Growth of new lymphatic vessels, lymphangiogenesis, is activated in cancer and inflammation, but is largely inactive in normal physiology, and therefore offers therapeutic potential. Key mediators of lymphangiogenesis have been identified in developmental studies. During embryonic development, lymphatic endothelial cells derive from the blood vascular endothelium and differentiate under the guidance of lymphatic-specific regulators, such as the prospero homeobox 1 transcription factor. Vascular endothelial growth factor-C (VEGF-C) and VEGF receptor 3 signaling are essential for the further development of lymphatic vessels and therefore they provide a promising target for inhibition of tumor lymphangiogenesis. Lymphangiogenesis is important for the progression of solid tumors as shown for melanoma and breast cancer. Tumor cells may use chemokine gradients as guidance cues and enter lymphatic vessels through intercellular openings between endothelial cell junctions or, possibly, by inducing larger discontinuities in the endothelial cell layer. Tumor-draining sentinel lymph nodes show enhanced lymphangiogenesis even before cancer metastasis and they may function as a permissive 'lymphovascular niche' for the survival of metastatic cells. Although our current knowledge indicates that the development of anti-lymphangiogenic therapies may be beneficial for the treatment of cancer patients, several open questions remain with regard to the frequency, mechanisms and biological importance of lymphatic metastases.

Lymphatic vessels and high endothelial venules are increased in the sentinel lymph nodes of patients with oral squamous cell carcinoma before the arrival of tumor cells

PURPOSE

To investigate the change of vasculature in the sentinel lymph node (SLN) of patients with oral squamous cell carcinoma.

METHODS

Immunohistochemical staining of SLNs in 58 patients was performed with two monoclonal antibodies (MAb): anti-D2-40 MAb for lymphatic endothelial cells, and anti-MECA-79 MAb for high endothelial venules (HEV). Twelve metastatically involved (m(+)) SLNs, 120 uninvolved (m(-)) SLNs, and 35 non-SLNs (control) were available for analyses. Vessel densities were measured by computer-assisted analyses in the entire region of SLN. Correlations were assessed between vessel density and clinicopathologic variables, including vascular endothelial growth factor C of primary tumor.

RESULTS

Lymphatic vessel density (LVD) in SLNs was higher than that in control LNs [2361.8 μm(2)/high-power field (HPF) (624.3-4758.5) vs. 1621.9 μm(2)/HPF (465.3-3453.5), P = 0.005]. LVD of m(-) SLNs [2662.4 μm(2)/HPF (624.3-4758.5)] and m(±) SLNs [4946.6 μm(2)/HPF (2009.3-8698.8)] were both statistically significantly higher compared to control. HEV densities in m(-) SLNs [14029.7 μm(2)/HPF (10465.7-17927.1)] as well as m(±) SLNs [18258.5 μm(2)/HPF (8408.9-27706.0)] were also significantly higher than those in control [10350.5 μm(2)/HPF (7807.8-12541.1)]. By multivariate analysis, the degree of vascular endothelial growth factor C expression of primary tumor showed significant correlation with LVD of SLNs (odds ratio 9.46, 95% confidence interval 1.73-51.5, P = 0.009), which was not the case in HEV.

CONCLUSIONS

Lymphatic vessels and HEVs were increased in SLNs, regardless of metastatic status of SLNs. Vascular endothelial growth factor C expression of primary tumor may contribute to the premetastatic change within SLNs of oral squamous cell carcinoma.

Endostatin suppresses colorectal tumor-induced lymphangiogenesis by inhibiting expression of fibronectin extra domain A and integrin α9

Endostatin is a natural occurring anti-angiogenic peptide and has been shown to inhibit tumor lymphangiogenesis by suppressing the expression of tumor-stimulating growth factors. We have previously shown that fibronectin alternative extra domain A (EDA) facilitates lymphangiogenesis of colorectal tumors. Since it is known that EDA interacts with integrin α9 in the lymphatic endothelial cells (LECs), we hypothesized that endostatin may target EDA-integrin α9 pathway to inhibit colorectal tumor-induced lymphangiogenesis. To test this hypothesis, we examined the effect of endostatin on EDA secreted by SW480 colorectal cancer cells and treated human LECs with different doses of endostatin in the presence of conditional medium from SW480 cells. We found that endostatin significantly reduced EDA secretion by SW480 cells and the expression of integrin α9 in LECs. Immunofluorescence studies showed that EDA and integrin α9 colocalized on the cell membrane of LECs and these colocalizations were dramatically reduced by endostatin. Co-immunoprecipitation studies demonstrated that EDA interacted with integrin α9 in LECs, and showed that endostatin treatment inhibited the formation of EDA-integrin α9 complex in LECs. Furthermore, we found that the arrangement and polarity of LEC cytoskeletons were destroyed by endostatin substantially, leading to a reduced formation of tube-like structures of LECs and a suppressed chemotaxis of LECs toward SW480 cells. Consistently, EDA and integrin α9 expressions as well as lymphangiogenesis were significantly suppressed by endostatin in colorectal cancer xenografts. In conclusion, our results suggest that endostatin reduces colorectal tumor-induced lymphangiogenesis, at least in part, by inhibiting EDA-integrin α9 pathway.

Lymphangiogenesis in cancers: A therapy target

Tumor metastasis is a major cause of death among cancer patients. The lymphatic vasculature is an important route for the metastatic spread of cancer. Recent research has indicated that vascular endothelial growth factor C (VEGF-C), VEGF-D and VEGF receptor-3 (VEGFR-3) are closely related to tumor-induced lymphangiogenesis, tumor metastasis and prognosis. Numerous studies demonstrate that the VEGF-C/VEGF-D/VEGFR-3 signaling axis plays a leading role in the regulation of tumor lymphangiogenesis and is related to tumor metastasis and prognosis. It has been confirmed that inhibition of the VEGF-C/VEGF-D/VEGFR-3 signaling axis can exert anti-lymphangiogenic effect and thereby prevent tumor metastasis in animal models. In this paper we review the molecular biology of lymphangiogenesis, its relationship with cancer metastasis, and the clinical implications of inhibition of lymphangiogenesis.

A role for bone morphogenetic protein-4 in lymph node vascular remodeling and primary tumor growth

Lymph node metastasis, an early and prognostically important event in the progression of many human cancers, is associated with expression of VEGF-D. Changes to lymph node vasculature that occur during malignant progression may create a metastatic niche capable of attracting and supporting tumor cells. In this study, we sought to characterize molecules expressed in lymph node endothelium that could represent therapeutic or prognostic targets. Differential mRNA expression profiling of endothelial cells from lymph nodes that drained metastatic or nonmetastatic primary tumors revealed genes associated with tumor progression, in particular bone morphogenetic protein-4 (BMP-4). Metastasis driven by VEGF-D was associated with reduced BMP-4 expression in high endothelial venules, where BMP-4 loss could remodel the typical high-walled phenotype to thin-walled vessels. VEGF-D expression was sufficient to suppress proliferation of the more typical BMP-4-expressing high endothelial venules in favor of remodeled vessels, and mechanistic studies indicated that VEGF receptor-2 contributed to high endothelial venule proliferation and remodeling. BMP-4 could regulate high endothelial venule phenotype and cellular function, thereby determining morphology and proliferation responses. Notably, therapeutic administration of BMP-4 suppressed primary tumor growth, acting both at the level of tumor cells and tumor stromal cells. Together, our results show that VEGF-D-driven metastasis induces vascular remodeling in lymph nodes. Furthermore, they implicate BMP-4 as a negative regulator of this process, suggesting its potential utility as a prognostic marker or antitumor agent.

Digging deeper into lymphatic vessel formation in vitro and in vivo

BACKGROUND

Abnormal lymphatic vessel formation (lymphangiogenesis) is associated with different pathologies such as cancer, lymphedema, psoriasis and graft rejection. Lymphatic vasculature displays distinctive features than blood vasculature, and mechanisms underlying the formation of new lymphatic vessels during physiological and pathological processes are still poorly documented. Most studies on lymphatic vessel formation are focused on organism development rather than lymphangiogenic events occurring in adults. We have here studied lymphatic vessel formation in two in vivo models of pathological lymphangiogenesis (corneal assay and lymphangioma). These data have been confronted to those generated in the recently set up in vitro model of lymphatic ring assay. Ultrastructural analyses through Transmission Electron Microscopy (TEM) were performed to investigate tube morphogenesis, an important differentiating process observed during endothelial cell organization into capillary structures.

RESULTS

In both in vivo models (lymphangiogenic corneal assay and lymphangioma), migrating lymphatic endothelial cells extended long processes exploring the neighboring environment and organized into cord-like structures. Signs of intense extracellular matrix remodeling were observed extracellularly and inside cytoplasmic vacuoles. The formation of intercellular spaces between endothelial cells led to tube formation. Proliferating lymphatic endothelial cells were detected both at the tips of sprouting capillaries and inside extending sprouts. The different steps of lymphangiogenesis observed in vivo are fully recapitulated in vitro, in the lymphatic ring assay and include: (1) endothelial cell alignment in cord like structure, (2) intracellular vacuole formation and (3) matrix degradation.

CONCLUSIONS

In this study, we are providing evidence for lymphatic vessel formation through tunneling relying on extensive matrix remodeling, migration and alignment of sprouting endothelial cells into tubular structures. In addition, our data emphasize the suitability of the lymphatic ring assay to unravel mechanisms underlying lymphangiogenesis.

Role of endoglin and VEGF family expression in colorectal cancer prognosis and anti-angiogenic therapies

Colorectal cancer (CRC) is one of the cancer models and most of the carcinogenic steps are presently well understood. Therefore, successful preventive measures are currently used in medical practice. However, CRC is still an important public health problem as it is the third most common cancer and the fourth most frequent cause of cancer death worldwide. Nowadays, pathologic stage is a unique and well-recognized prognostic indicator, however, more accurate indicators of the biologic behavior of CRC are expected to improve the specificity of medical treatment. Angiogenesis plays an important role in the growth and progression of cancer but its role as a prognostic factor is still controversial. Probably the most important clinical implication of tumor angiogenesis is the development of anti-angiogenic therapy. The goal of this review is to critically evaluate the role of angiogenic markers, assessed by either endoglin-related microvessel density or expression of vascular endothelial growth factor family members in the CRC setting and discuss the role of these angiogenic markers in anti-angiogenic therapies.

Immunostaining patterns of CD31 and podoplanin in previously untreated advanced oral/oropharyngeal cancer: prognostic implications

BACKGROUND

The objective of this study was to assess angiogenesis and lymphangiogenesis patterns in advanced oral/oropharyngeal cancer by immunohistochemical techniques.

METHODS

Forty-five patients with advanced oral/oropharyngeal cancer, treated by primary surgery between January 1996 and December 2005, were selected. All cases were followed for at least 24 months. Angiogenesis and lymphangiogenesis were evaluated with antibodies against CD31 and podoplanin, respectively. Survival outcomes were calculated by the Kaplan-Meier method, whereas univariate comparisons were obtained by log-rank, chi-square, and Mann-Whitney tests.

RESULTS

Survival correlated with the area of peritumoral blood vessels (p = .02), whereas the number of intratumoral lymphatics (p = .02) correlated with the occurrence of nodal metastasis. The risk for distant metastasis correlated with the perimeter of intratumoral lymphatics (p = .02).

CONCLUSIONS

Peritumoral angiogenesis presented different expression patterns between survivors and patients who died of disease. Intratumoral lymphangiogenesis was correlated with a higher risk of developing lymph node (LN) and distant metastasis.

Interstitial fluid: the overlooked component of the tumor microenvironment?

Background

The interstitium, situated between the blood and lymph vessels and the cells, consists of a solid or matrix phase and a fluid phase, together constituting the tissue microenvironment. Here we focus on the interstitial fluid phase of tumors, i.e., the fluid bathing the tumor and stromal cells. Novel knowledge on this compartment may provide important insight into how tumors develop and how they respond to therapy.

Results

We discuss available techniques for interstitial fluid isolation and implications of recent findings with respect to transcapillary fluid balance and uptake of macromolecular therapeutic agents. By the development of new methods it is emerging that local gradients exist in signaling substances from neoplastic tissue to plasma. Such gradients may provide new insight into the biology of tumors and mechanistic aspects linked to therapy. The emergence of sensitive proteomic technologies has made the interstitial fluid compartment in general and that of tumors in particular a highly valuable source for tissue-specific proteins that may serve as biomarker candidates. Potential biomarkers will appear locally at high concentrations in the tissue of interest and will eventually appear in the plasma, where they are diluted.

Conclusions

Access to fluid that reliably reflects the local microenvironment enables us to identify substances that can be used in early detection and monitoring of disease.

Does plasminogen activator inhibitor-1 drive lymphangiogenesis?

The purpose of this study is to explore the function of plasminogen activator inhibitor-1 (PAI-1) during pathological lymphangiogenesis. PAI-1, the main physiological inhibitor of plasminogen activators is involved in pathological angiogenesis at least by controlling extracellular proteolysis and by regulating endothelial cell survival and migration. Protease system's role in lymphangiogenesis is unknown yet. Thus, based on its important pro-angiogenic effect, we hypothesized that PAI-1 may regulate lymphangiogenesis associated at least with metastatic dissemination of cancer cells. To address this issue, we studied the impact of PAI-1 deficiency in various murine models of tumoral lymphangiogenesis. Wild-type PAI-1 proficient mice were used as controls. We provide for the first time evidence that PAI-1 is dispensable for tumoral lymphangiogenesis associated with breast cancers either induced by mammary carcinoma cell injection or spontaneously appearing in transgenic mice expressing the polyomavirus middle T antigen (PymT) under the control of a mouse mammary tumor virus long-terminal repeat promoter (MMTV-LTR). We also investigated inflammation-related lymphatic vessel recruitment by using two inflammatory models. PAI-1 deficiency did neither affect the development of lymphangioma nor burn-induced corneal lymphangiogenesis. These novel data suggest that vascular remodelling associated with lymphangiogenesis and angiogenesis involve different molecular determinants. PAI-1 does not appear as a potential therapeutic target to counteract pathological lymphangiogenesis.

Delphinidin inhibits a broad spectrum of receptor tyrosine kinases of the ErbB and VEGFR family

Delphinidin has been reported to inhibit EGFR signalling. To determine whether other receptor tyrosine kinases (RTKs) are also influenced by delphinidin, we examined its ability to inhibit the kinase activity of EGFR, ErbB2, VEGFR-2, VEGFR-3 and IGF1R in a cell-free test system. We found that delphinidin strongly inhibited the protein tyrosine kinase activity of all tested RTKs at low micromolar concentrations. In A431 and PAE cells, ligand-induced phosphorylation of the receptors was also potently suppressed, with a preference for the suppression of the activity of ErbB3 (IC(50) approximately 100 nM) and VEGFR-3 (IC(50) < 50 microM). Thus the inhibition of RTKs by delphinidin is not limited to cell-free assays but is also of relevance in the cellular context. The results indicate that delphinidin acts as a broad-spectrum inhibitor of RTKs. Given the crucial role of the receptors in tumour growth and metastasis, we conclude that delphinidin has the potential to act directly against tumour cells as well as to interfere with key tumour-host interactions, although the suitability of delphinidin as a drug in cancer management may be compromised by its limited stability. Nevertheless, delphinidin may represent a novel lead compound for the development of chemopreventative and chemotherapeutic intervention strategies.

Inhibition of angiotensin II receptor 1 limits tumor-associated angiogenesis and attenuates growth of murine melanoma

PURPOSE

We evaluated the involvement of angiotensin II (AngII)-dependent pathways in melanoma growth, through the pharmacological blockage of AT1 receptor by the anti-hypertensive drug losartan (LOS).

RESULTS

We showed immunolabeling for both AngII and the AT1 receptor within the human melanoma microenvironment. Like human melanomas, we showed that murine melanomas also express the AT1 receptor. Growth of murine melanoma, both locally and at distant sites, was limited in mice treated with LOS. The reduction in tumor growth was accompanied by a twofold decrease in tumor-associated microvessel density and by a decrease in CD31 mRNA levels. While no differences were found in the VEGF expression levels in tumors from treated animals, reduction in the expression of the VEGFR1 (Flt-1) at the mRNA and protein levels was observed. We also showed downregulation of mRNA levels of both Flt-4 and its ligand, VEGF-C.

CONCLUSIONS

Together, these results show that blockage of AT1 receptor signaling may be a promising anti-tumor strategy, interfering with angiogenesis by decreasing the expression of angiogenic factor receptors.

Small molecule chloropyramine hydrochloride (C4) targets the binding site of focal adhesion kinase and vascular endothelial growth factor receptor 3 and suppresses breast cancer growth in vivo

FAK is a tyrosine kinase that functions as a key orchestrator of signals leading to invasion and metastasis. Since FAK interacts directly with a number of critical proteins involved in survival signaling in tumor cells, we hypothesized that targeting a key protein-protein interface with druglike small molecules was a feasible strategy for inhibiting tumor growth. In this study, we targeted the protein-protein interface between FAK and VEGFR-3 and identified compound C4 (chloropyramine hydrochloride) as a drug capable of (1) inhibiting the biochemical function of VEGFR-3 and FAK, (2) inhibiting proliferation of a diverse set of cancer cell types in vitro, and (3) reducing tumor growth in vivo. Chloropyramine hydrochloride reduced tumor growth as a single agent, while concomitant administration with doxorubicin had a pronounced synergistic effect. Our data demonstrate that the FAK-VEGFR-3 interaction can be targeted by small druglike molecules and this interaction can provide the basis for highly specific novel cancer therapeutics.

Vascular endothelial growth factor-D is correlated with hepatic metastasis from gastric cancer after radical gastrectomy

BACKGROUND

Vascular endothelial growth factor-D (VEGF-D), the activating ligand for vascular endothelial growth factor receptor-3 (VEGFR-3), has been identified as an important endogenic tumor-associated lymphangiogenic factors which can promote lymphatic metastasis from primary tumor. Lymphatic metastasis, which is the most common metastatic method of gastric cancer (GC), is still deemed a potentially relative indicator of distant metastasis from GC. We hypothesize that VEGF-D is associated with hepatic metastasis (HM) from GC after radical gastrectomy by promoting lymphatic metastasis and/or hematogenous metastasis.

METHODS

This study included 150 GC patients who underwent radical gastrectomy (75 cases presented with HM and 75 cases presented without any recurrences). VEGF-D, VEGF-C, VEGF-A, VEGFR-2, VEGFR-3, and microvessel density (MVD) were evaluated by immunohistochemistry. Besides, clinicopathologic variables and prognosis of GC patients were analyzed statistically.

RESULTS

Significant associations were seen between Lauren classification and HM, VEGF-D and HM, VEGFR-3 and HM, MVD and HM, and between nodal status and HM. VEGF-D remained an independent factor for HM from GC after radical gastrectomy. Further significant association was evaluated between high-grade VEGF-D expression and short disease-free survival of HM from GC after radical gastrectomy.

CONCLUSION

VEGF-D, which can induce lymphangiogenesis specifically in many kinds of malignant diseases, is an important factor for predicting HM from GC following radical gastrectomy.

Safety and efficacy of sunitinib in patients with advanced hepatocellular carcinoma: an open-label, multicentre, phase II study

BACKGROUND

Hepatocellular carcinoma (HCC) tumour spread is partly dependent on neoangiogenesis. In this open-label, multicentre, phase II trial done in Europe and Asia, sunitinib, a multitargeted tyrosine-kinase inhibitor with anti-angiogenic properties, was assessed in patients with advanced unresectable HCC.

METHODS

Between February and July, 2006, eligible patients were enrolled and treated with repeated cycles of oral sunitinib (50 mg/day for 4 weeks, followed by 2 weeks off treatment). The primary endpoint of this Simon two-stage phase II trial was objective response rate according to Response Evaluation Criteria in Solid Tumours (RECIST) criteria, with an expected response rate of 15%. This trial is registered with ClinicalTrials.gov, number NCT00247676.

FINDINGS

Of 37 patients enrolled, one (2.7%) patient experienced a confirmed partial response, giving an overall objective response rate of 2.7% (95% CI 0.1-14.2); on the basis of this, the trial did not proceed to the second stage. 13 (35%) of 37 patients achieved stable disease for over 3 months. Commonly observed grade 3 and 4 adverse events included thrombocytopenia (14 of 37; 37.8%), neutropenia (nine of 37; 24.3%), asthenia (five of 37; 13.5%), hand-foot syndrome (four of 37; 10.8%), and anaemia (four of 37; 10.8%). There were four deaths among the 37 patients (10.8%) that were possibly related to treatment.

INTERPRETATION

Sunitinib showed pronounced toxicities at a dose of 50 mg/day in patients with unresectable HCC. The response rate was low, and the study did not meet the primary endpoint based on RECIST criteria.

FUNDING

Pfizer Oncology.