Tumor lymphangiogenesis and lymphangiogenic growth factors

Lymph Node Metastasis in Gastrointestinal Carcinomas: A View from a Proteomics Perspective

Lymph node metastasis (LNM) is one of the major prognostic factors in human gastrointestinal carcinomas (GICs). The lymph node-positive patients have poorer survival than node-negative patients. LNM is directly associated with the recurrence and poor survival of patients with GICs. The early detection of LNM in patients and designing effective therapies to suppress LNM may significantly impact the survival of these patients. The rapid progress made in proteomic technologies could be successfully applied to identify molecular targets for cancers at high-throughput levels. LC-MS/MS analysis enables the identification of proteins involved in LN metastasis, which can be utilized for diagnostic and therapeutic applications. This review summarizes the studies on LN metastasis in GICs using proteomic approaches to date.

NAT10-mediated ac4C-modified ANKZF1 promotes tumor progression and lymphangiogenesis in clear-cell renal cell carcinoma by attenuating YWHAE-driven cytoplasmic retention of YAP1

BACKGROUND

Lymphatic metastasis is one of the most common metastatic routes and indicates a poor prognosis in clear-cell renal cell carcinoma (ccRCC). N-acetyltransferase 10 (NAT10) is known to catalyze N4-acetylcytidine (ac4C) modification of mRNA and participate in many cellular processes. However, its role in the lymphangiogenic process of ccRCC has not been reported. This study aimed to elucidate the role of NAT10 in ccRCC lymphangiogenesis, providing valuable insights into potential therapeutic targets for intervention.

METHODS

ac4C modification and NAT10 expression levels in ccRCC were assessed using public databases and clinical samples. Functional investigations involved manipulating NAT10 expression in cellular and mouse models to study its role in ccRCC. Mechanistic insights were gained through a combination of RNA sequencing, mass spectrometry, co-immunoprecipitation, RNA immunoprecipitation, immunofluorescence, and site-specific mutation analyses.

RESULTS

We found that ac4C modification and NAT10 expression levels increased in ccRCC. NAT10 promoted tumor progression and lymphangiogenesis of ccRCC by enhancing the nuclear import of Yes1-associated transcriptional regulator (YAP1). Subsequently, we identified ankyrin repeat and zinc finger peptidyl tRNA hydrolase 1 (ANKZF1) as the functional target of NAT10, and its upregulation in ccRCC was caused by NAT10-mediated ac4C modification. Mechanistic analyses demonstrated that ANKZF1 interacted with tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein epsilon (YWHAE) to competitively inhibit cytoplasmic retention of YAP1, leading to transcriptional activation of pro-lymphangiogenic factors.

CONCLUSIONS

These results suggested a pro-cancer role of NAT10-mediated acetylation in ccRCC and identified the NAT10/ANKZF1/YAP1 axis as an under-reported pathway involving tumor progression and lymphangiogenesis in ccRCC.

Downregulation of ITGA5 inhibits lymphangiogenesis and cell migration and invasion in male laryngeal squamous cell carcinoma

ITGA5, a fibronectin receptor was highly expressed in laryngeal squamous cell carcinoma (LSCC) samples and was related to poor survival. However, the potential mechanism remains unclear. To elucidate the regulatory role of ITGA5 in LSCC progression, we investigated the effect of ITGA5 expression on lymphangiogenesis, migration, and invasion of LSCC cells in vitro and in vivo using immunohistochemistry, siRNA transfection, qRT-PCR, western blotting, enzyme-linked immunosorbent assay, flow cytometry, transwell co-culture, tube formation, cell migration, and invasion assays, and a subcutaneous graft tumor model. The expression of ITGA5 was higher in the LSCC tissues and linked to lymph node metastasis and T staging. Moreover, ITGA5 expression was significantly positively correlated with VEGF-C expression, and the lymphatic vessel density of patients with high ITGA5 expression was noticeably higher than that of patients with low ITGA5 expression. Additionally, it was found in vitro that downregulation of ITGA5 expression not only inhibited the expression and secretion of VEGF-C, but also suppressed the tube-forming ability of human lymphatic endothelial cells (HLECs) and the migration and invasion ability of LSCC cells, while exogenous VEGF-C supplementation reversed these phenomena. Furthermore, a tumor xenograft assay showed that si-ITGA5 restrained the growth and metastasis of TU212-derived tumors in vivo. Our findings suggested that ITGA5 induces lymphangiogenesis and LSCC cell migration and invasion by enhancing VEGF-C expression and secretion.

Interactions between Platelets and Tumor Microenvironment Components in Ovarian Cancer and Their Implications for Treatment and Clinical Outcomes

Platelets, the primary operatives of hemostasis that contribute to blood coagulation and wound healing after blood vessel injury, are also involved in pathological conditions, including cancer. Malignancy-associated thrombosis is common in ovarian cancer patients and is associated with poor clinical outcomes. Platelets extravasate into the tumor microenvironment in ovarian cancer and interact with cancer cells and non-cancerous elements. Ovarian cancer cells also activate platelets. The communication between activated platelets, cancer cells, and the tumor microenvironment is via various platelet membrane proteins or mediators released through degranulation or the secretion of microvesicles from platelets. These interactions trigger signaling cascades in tumors that promote ovarian cancer progression, metastasis, and neoangiogenesis. This review discusses how interactions between platelets, cancer cells, cancer stem cells, stromal cells, and the extracellular matrix in the tumor microenvironment influence ovarian cancer progression. It also presents novel potential therapeutic approaches toward this gynecological cancer.

3-O-Acetyloleanolic acid inhibits angiopoietin-1-induced angiogenesis and lymphangiogenesis via suppression of angiopoietin-1/Tie-2 signaling

Tumor angiogenesis and lymphangiogenesis are important processes in tumor progression and metastasis. The inhibitory effects of 3-O-acetyloleanolic acid (3AOA), a pentacyclic triterpenoid compound isolated from Vigna sinensis K., on tumor-induced angiogenesis and lymphangiogenesis in vitro and in vivo were studied. Angiopoietin-1 is an important angiogenic and lymphangiogenic factor secreted from colon carcinoma CT-26 cells under hypoxia conditions. 3AOA inhibited proliferation, migration, and tube formation of angiopoietin-1-treated human umbilical vein endothelial cells (HUVEC) and human lymphatic microvascular endothelial cells (HLMEC). 3AOA reduced angiogenesis and lymphangiogenesis in angiopoietin-1-stimulated Matrigel plugs. Also, 3AOA inhibited tumor growth and tumor-induced angiogenesis and lymphangiogenesis in an angiopoietin-1-induced CT-26 allograft colon carcinoma animal model. 3AOA inhibited activation of the angiopoietin-1 receptor Tie-2 and activation of the downstream signaling factors FAK, AKT, and ERK1/2 that are involved in the angiopoietin-1/Tie-2-signaling pathway. Thus, 3AOA has an inhibitory effect on angiogenesis and lymphangiogenesis induced by angiopoietin-1 both in vitro and in vivo, and the inhibitory effect of 3AOA is probably due to suppression of angiopoietin-1/Tie-2 signaling in HUVEC and HLMEC.

Small Peptide Modulation of Fibroblast Growth Factor Receptor 3-Dependent Postnatal Lymphangiogenesis

BACKGROUND

The fibroblast growth factor receptor (FGFR) family includes transmembrane receptors involved in a wide range of developmental and postdevelopmental biologic processes as well as a wide range of human diseases. In particular, FGFR3 has been implicated in the mechanism by which 9-cis retinoic acid (9-cisRA) induces lymphangiogenesis and improves lymphedema. The purpose of this study was to validate the efficacy of a novel small peptide FGFR3 inhibitor, peptide P3 (VSPPLTLGQLLS), and to elucidate the role of FGFR3 in 9-cisRA-induced lymphangiogenesis using this peptide.

METHODS AND RESULTS

Peptide P3 effectively inhibited FGFR3 phosphorylation. In vitro, peptide P3-mediated FGFR3 inhibition did not decrease lymphatic endothelial cell (LEC) proliferation, migration, or tubule formation. However, peptide P3-mediated FGFR3 inhibition did block 9-cisRA-stimulated LEC proliferation, migration, and tubule formation. In vivo, peptide P3-mediated FGFR3 inhibition was sufficient to inhibit 9-cisRA-induced tracheal lymphangiogenesis.

CONCLUSION

FGFR3 does not appear to be essential to nonpromoted LEC proliferation, migration, and tubule formation. However, FGFR3 may play a key role in LEC proliferation, migration, tubule formation, and postnatal in vivo lymphangiogenesis when pharmacologically induced by 9-cisRA. P3 may have the potential to be used as a precise regulatory control element for 9-cisRA-mediated lymphangiogenesis.

Critical review: Cardiac telocytes vs cardiac lymphatic endothelial cells

The study of cardiac interstitial Cajal-like cells (ICLCs) began in 2005 and continued until 2010, when these cells were renamed as telocytes (TCs). Since then, numerous papers on cardiac ICLCs and TCs have been published. However, in the initial descriptions upon which further research was based, lymphatic endothelial cells (LECs) and initial lymphatics were not considered. No specific antibodies for LECs (such as podoplanin or LYVE-1) were used in cardiac TC studies, although ultrastructurally, LECs and TCs have similar morphological traits, including the lack of a basal lamina. When tissues are longitudinally cut, migrating LECs involved in adult lymphangiogenesis have an ICLC or TC morphology, both in light and transmission electron microscopy. In this paper, we present evidence that at least some cardiac TCs are actually LECs. Therefore, a clear-cut distinction should be made between TCs and LECs, at both the molecular and the ultrastructural levels, in order to avoid obtaining invalid data.

The chromosome 11q13.3 amplification associated lymph node metastasis is driven by miR-548k through modulating tumor microenvironment

Background

The prognosis for esophageal squamous cell carcinoma (ESCC) patients with lymph node metastasis (LNM) is still dismal. Elucidation of the LNM associated genomic alteration and underlying molecular mechanisms may provide clinical therapeutic strategies for ESCC treatment.

Methods

Joint analysis of ESCC sequencing data were conducted to comprehensively survey SCNAs and identify driver genes which significantly associated with LNM. The roles of miR-548k in lymphangiogensis and lymphatic metastasis were validated both in vitro and in vivo. ESCC tissue and blood samples were analyzed for association between miR-548k expression and patient clinicopathological features and prognosis and diagnosis.

Results

In the pooled cohort of 314 ESCC patients, we found 76 significant focused regions including 43 amplifications and 33 deletions. Clinical implication analysis revealed a panel of genes associated with LNM with the most frequently amplified gene being MIR548K harbored in the 11q13.3 amplicon. Overexpression of miR-548k remarkably promotes lymphangiogenesis and lymphatic metastasis in vitro and in vivo. Furthermore, we demonstrated that miR-548k modulating the tumor microenvironment by promoting VEGFC secretion and stimulating lymphangiogenesis through ADAMTS1/VEGFC/VEGFR3 pathways, while promoting metastasis by regulating KLF10/EGFR axis. Importantly, we found that serum miR-548k and VEGFC of early stage ESCC patients were significantly higher than that in healthy donators, suggesting a promising application of miR-548k and VEGFC as biomarkers in early diagnosis of ESCC.

Conclusions

Our study comprehensively characterized SCNAs in ESCC and highlighted the crucial role of miR-548k in promoting lymphatic metastasis, which might be employed as a new diagnostic and prognostic marker for ESCC.

Electronic supplementary material

The online version of this article (10.1186/s12943-018-0871-4) contains supplementary material, which is available to authorized users.

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.

A Novel Role of Cab45-G in Mediating Cell Migration in Cancer Cells

Ca²⁺-binding protein of 45 kDa (Cab45), a CREC family member, is reported to be associated with Ca²⁺-dependent secretory pathways and involved in multiple diseases including cancers. Cab45-G, a Cab45 isoform protein, plays an important role in protein sorting and secretion at Golgi complex. However, its role in cancer cell migration remains elusive. In this study, we demonstrate that Cab45-G exhibited an increased expression in cell lines with higher metastatic potential and promoted cell migration in multiple types of cancer cells. Overexpression of Cab45-G resulted in an altered expression of the molecular mediators of epithelial-mesenchymal transition (EMT), which is a critical step in the tumor metastasis. Quantitative real-time PCR showed that overexpression of Cab45-G increased the expression of matrix metalloproteinase-2 and -7 (MMP-2 and MMP-7). Conversely, knock-down of Cab45-G reduced the expression of the above MMPs. Moreover, forced expression of Cab45-G upregulated the level of phosphorylated ERK and modulated the secretion of extracellular proteins fibronectin and fibulin. Furthermore, in human cervical and esophageal cancer tissues, the expression of Cab45-G was found to be significantly correlated with that of MMP-2, further supporting the importance of Cab45-G on regulating cancer metastasis. Taken together, these results suggest that Cab45-G could regulate cancer cell migration through various molecular mechanisms, which may serve as a therapeutic target for the treatment of cancers.

The lymphatic system and pancreatic cancer

This review summarizes current knowledge of the biology, pathology and clinical understanding of lymphatic invasion and metastasis in pancreatic cancer. We discuss the clinical and biological consequences of lymphatic invasion and metastasis, including paraneoplastic effects on immune responses and consider the possible benefit of therapies to treat tumors that are localized to lymphatics. A review of current techniques and methods to study interactions between tumors and lymphatics is presented.

Lymphatic drainage from the eye: A new target for therapy

Lowering intraocular pressure (IOP) has been central to glaucoma care for over a century. In order to prevent sight loss from disease, there has been considerable focus on medical and surgical methods to improve fluid drainage from the eye. In spite of this, our understanding of exactly how aqueous humor leaves the eye is not complete. Recently, lymphatic vessels have been discovered in the human uvea, with studies showing lymphatic fluid outflow in several models, in addition to evidence for their pharmacological enhancement. The presence of a lymphatic outflow system points to an exciting, expanded understanding of how fluid and particulate materials such as proteins move out of the eye, and how IOP may be regulated. We coin the term "uveolymphatic pathway"-to reflect a comprehensive and compelling new target for glaucoma and an exciting opportunity for future investigations to better understand the eye in health and disease.

HIF-2α attenuates lymphangiogenesis by up-regulating IGFBP1 in hepatocellular carcinoma

BACKGROUND INFORMATION

Tumour-associated lymphangiogenesis was identified as an important clinical determinant for the prognosis of hepatocellular carcinoma (HCC) and significantly influences patient survival. However, in this context, little is known about regulation of lymphangiogenesis by hypoxia-inducible factors (HIF). In HCC, mainly HIF-1α was positively correlated with lymphatic invasion and metastasis, whereas a defined role of HIF-2α is missing.

RESULTS

We created a stable knockdown (k/d) of HIF-1α and HIF-2α in HepG2 cells and generated co-cultures of HepG2 spheroids with embryonic bodies. This constitutes an in vitro tumour model mimicking the cancer microenvironment and allows addressing the role of distinct HIF isoforms in regulating HCC lymphangiogenesis. In co-cultures with a HIF-2α k/d, lymphangiogenesis was significantly increased, whereas the k/d of HIF-1α showed no effect. The HIF-2α-dependent lymphangiogenic phenotype was confirmed in vivo using matrigel plug assays with supernatants of HIF-2α k/d HepG2 cells. We identified and verified insulin-like growth factor binding protein 1 (IGFBP1) as a HIF-2α target gene. The potential of HepG2 cells to induce lymphangiogenesis in two independent functional assays was significantly enhanced either by a k/d of HIF-2α or by silencing IGFBP1. Moreover, we confirmed IGF as a potent pro-lymphatic growth factor with IGFBP1 being its negative modulator.

CONCLUSIONS

We propose that HIF-2α acts as an important negative regulator of hepatic lymphangiogenesis in vitro and in vivo by inducing IGFBP1 and thus, interfering with IGF signalling. Therefore, HIF-2α may constitute a critical target in HCC therapy.

Corosolic Acid Exhibits Anti-angiogenic and Anti-lymphangiogenic Effects on In Vitro Endothelial Cells and on an In Vivo CT-26 Colon Carcinoma Animal Model

We describe the anti-angiogenic and anti-lymphangiogenic effects of corosolic acid, a pentacyclic triterpenoid isolated from Cornus kousa Burg. A mouse colon carcinoma CT-26 animal model was employed to determine the in vivo anti-angiogenic and anti-lymphangiogenic effects of corosolic acid. Corosolic acid induced apoptosis in CT-26 cells, mediated by the activation of caspase-3. In addition, it reduced the final tumor volume and the blood and lymphatic vessel densities of tumors, indicating that it suppresses in vivo angiogenesis and lymphangiogenesis. Corosolic acid inhibited the proliferation and tube formation of human umbilical vein endothelial cells and human dermal lymphatic microvascular endothelial cells. In addition, corosolic acid decreased the proliferation and migration of human umbilical vein endothelial cells stimulated by angiopoietin-1. Pretreatment with corosolic acid decreased the phosphorylation of focal adhesion kinase (FAK) and ERK1/2, suggesting that corosolic acid contains anti-angiogenic activity that can suppress FAK signaling induced by angiopoietin-1.

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.

Key architectural changes in tumor-negative lymph nodes from metastatic-free oral cancer patients are valuable prognostic factors

Regional lymph node (LN) metastasis in oral cancer patients is the most significant grave prognostic factor. We evaluated the relationship between clinical outcomes and different histopathological changes in tumor-negative LNs (LN0) selected from neck dissections without metastatic disease (pN0). A total of 435 LN0 selected from pN0 neck dissections (up to three nodes in each level) were scored for histopathological parameters of LN areas, capsule thickness, subcapsular and medullary sinus ectasia, lobular architecture and percent of cortical reactive follicles. These were compared to 328 LN0 selected from neck dissections with metastases (pN+) after exclusion of metastatic LNs. Data were presented by maximum scores of each parameter in I-III (close) and in IV-V (distant) levels. Limited data from level V and regression analyses inferred that the values in level IV represented the worst changes for most patients. Cox proportional hazard regression on each parameter in close and distant levels demonstrated that capsule thickness, number of lobules and percent of reactive follicles were significantly associated with time to death from disease. The higher the change in distant levels, the shorter the time to death, while the higher the change in close levels (given a stable change in distant levels), the longer the time to death. After adjustment for gender, age and location, only the effect of the percent of reactive follicles retained their significant effect. Logistic regression of metastases demonstrated that all parameters except for percent of reactive follicles were significantly associated with risk of metastases, with differences between close and distant levels similar to those found for time to death. After adjustment for gender, age and location, only the area and number of lobes retained their significance. The findings of this study suggested that selective histopathological changes in tumor-negative LNs in metastatic-free patients provide new valuable prognostic parameters.

Expression of MACC1 and c-Met in human gastric cancer and its clinical significance

BACKGROUND

Recent studies have suggested that the metastasis-associated colon cancer1 (MACC1) gene can promote tumor proliferation, invasion and metastasis through an upregulation of c-Met expression. However, its role in gastric cancer is controversial. Our study investigated expression of MACC1 and c-Met in gastric cancer, as well as correlated this with clinicopathological parameters.

METHODS

Expressions of MACC1 and c-Met protein in a sample of 98 gastric carcinoma and adjacent nontumorous tissues were detected by immunohistochemistry. Their relationships and correlations with clinicopathological features were analyzed.

RESULTS

The positive rates of MACC1 and c-Met protein in primary tumors were 61.22% and 59.18%, respectively. A significant correlation was found between expression of MACC1 and c-Met (P<0.05). Expression of the MACC1 protein in gastric cancer tissue was correlated with lymph node metastasis (χ2 = 10.555,P = 0.001), peritoneal metastasis (χ2 = 5.694, P = 0.017), and hepatic metastasis (χ2 = 4.540,P = 0.033), but not with age, gender, tumor size, location, clinical stage or the distant metastases (P>0.05).

CONCLUSION

The positive rate of MACC1 protein expression was related to the protein expression of c-Met. Both had a correlation with the presence of peritoneal metastasis, lymph node metastasis and hepatic metastasis, all of which contribute to a poor prognosis for gastric cancer patients.

STAT3 targets suggest mechanisms of aggressive tumorigenesis in diffuse large B-cell lymphoma

The signal transducer and activator of transcription 3 (STAT3) is a transcription factor that, when dysregulated, becomes a powerful oncogene found in many human cancers, including diffuse large B-cell lymphoma. Diffuse large B-cell lymphoma is the most common form of non-Hodgkin's lymphoma and has two major subtypes: germinal center B-cell-like and activated B-cell-like. Compared with the germinal center B-cell-like form, activated B-cell-like lymphomas respond much more poorly to current therapies and often exhibit overexpression or overactivation of STAT3. To investigate how STAT3 might contribute to this aggressive phenotype, we have integrated genome-wide studies of STAT3 DNA binding using chromatin immunoprecipitation-sequencing with whole-transcriptome profiling using RNA-sequencing. STAT3 binding sites are present near almost a third of all genes that differ in expression between the two subtypes, and examination of the affected genes identified previously undetected and clinically significant pathways downstream of STAT3 that drive oncogenesis. Novel treatments aimed at these pathways may increase the survivability of activated B-cell-like diffuse large B-cell lymphoma.

Insulin-like growth factor-1 induces lymphangiogenesis and facilitates lymphatic metastasis in colorectal cancer

AIM: To investigate the expression of insulin-like growth factor-1 (IGF-1)/insulin-like growth factor-1 receptor (IGF-1R) in colorectal cancer (CRC) tissues and to analyze their correlation with lymphangiogenesis and lymphatic metastasis.

METHODS: Immunohistochemistry was used to evaluate IGF-1 and IGF-1R expression and lymphatic vessel density (LVD) in 40 CRC specimens. The correlation between IGF-1/IGF-1R and LVD was investigated. Effects of IGF-1 on migration and invasion of CRC cells were examined using transwell chamber assays. A LoVo cell xenograft model was established to further detect the role of IGF-1 in CRC lymphangiogenesis in vivo.

RESULTS: Elevated IGF-1 and IGF-1R expression in CRC tissues was correlated with lymph node metastasis (r = 0.715 and 0.569, respectively, P < 0.05) and tumor TNM stage (r = 0.731 and 0.609, P < 0.05). A higher LVD was also found in CRC tissues and was correlated with lymphatic metastasis (r = 0.405, P < 0.05). A positive correlation was found between LVD and IGF-1R expression (r = 0.437, P < 0.05). Transwell assays revealed that IGF-1 increased the migration and invasion of CRC cells. In vivo mouse studies showed that IGF-1 also increased LVD in LoVo cell xenografts.

CONCLUSION: IGF-1/IGF-1R signaling induces tumor-associated lymphangiogenesis and contributes to lymphatic metastasis of CRC.

Lymphatic microvessel density and vascular endothelial growth factor-C and -D as prognostic factors in breast cancer: a systematic review and meta-analysis of the literature

The use of lymphatic microvessel density (LVD) and pro-lymphangiogenic mediators as prognostic factors for survival in breast cancer remains controversial. We searched the electronic databases PubMed and EMBASE without language restrictions for relevant literature to aggregate the survival results. To be eligible, every study had to include the assessment of the LVD or the expression of vascular endothelial growth factor (VEGF)-C or -D in patients with breast cancer and provide a survival comparison, including disease-free survival (DFS) or overall survival (OS), according to the LVD, VEGF-C or VEGF-D status. Across all studies, 56.64 % of patients were considered to have a VEGF-C-positive tumor, and 65.54 % of patients had VEGF-D-positive tumors. High LVD had an unfavorable impact on DFS, with a pooled hazard ratio (HR) of 2.222 (95 % CI 1.579-3.126) and an OS with a HR of 2.493 (95 % CI 1.183-5.25). According to the different lymphatic makers, the subgroup HR in the D2-40 studies was 2.431 (95 % CI 1.622-3.644) for DFS and 4.085 (95 % CI 1.896-8.799) for OS. VEGF-C overexpression, as assessed by immunochemistry, was a prognostic factor for decreased DFS (HR 2.164; 95 % CI 1.256-3.729) and for decreased OS (HR 2.613; 95 % CI 1.637-4.170). VEGF-D overexpression was a significant although weak prognostic factor for DFS only when assessed by immunochemistry, with a HR of 2.108 (95 % CI 1.014-4.384). Our meta-analysis demonstrated that LVD, VEGF-C and VEGF-D could predict poor prognosis in patients with breast cancer. However, standardization of the assessment of LVD and for the expression of lymphangiogenesis factors is needed.

Recombinant canstatin inhibits angiopoietin-1-induced angiogenesis and lymphangiogenesis

We describe the effect of recombinant canstatin, the NC1 domain of the α2 chain of Type IV collagen, on suppression of angiogenesis and lymphangiogenesis both in vitro and in vivo. Recombinant canstatin produced from stably transformed Drosophila S2 cells reduced the expression of angiopoietin-1 in hypoxia mimetic agent, CoCl(2) -treated CT-26 cells. Recombinant canstatin inhibited proliferation, tube formation and migration of human angiopoietin-1 (rhAngpt-1)-treated human umbilical vein endothelial cells (HUVEC) and lymphatic endothelial cells (LEC). Recombinant canstatin suppressed the expression of Tie-2 and vascular endothelial growth factor-3 (VEGFR-3) transcripts in rhAngpt-1-treated HUVEC and LEC, respectively. The inhibitory effect of recombinant canstatin on tumor growth was also investigated using a heterotopic CT-26 colon carcinoma animal (BALB/c mice) model. Recombinant canstatin reduced the final volume and weight of tumors, and blood and lymphatic vessel densities of tumors, which were evaluated by CD-31 and LYVE-1 immunostaining. Immunohistochemical analysis showed that recombinant canstatin dramatically reduced the expression of angiopoietin-1 in CT-26 colon carcinoma-induced tumor, but not the expression of VEGF-C. Tie-2 and VEGFR-3 expressions were also reduced in recombinant canstatin-treated tumors. These results indicate that recombinant canstatin has anti-tumoral activities against CT-26 colon carcinoma cells. Recombinant canstatin reduces the expression of angiopoietin-1 in hypoxia-induced CT-26 cells and inhibits the angiogenic and lymphangiogenic signaling induced by angiopoietin-1. Recombinant canstatin probably inhibits angiogenesis and lymphangiogenesis via suppression of the integrin-dependent FAK signaling induced by angiopoietin-1/Tie-2 and/or VEGFR-3.

Erythropoietin induces lymph node lymphangiogenesis and lymph node tumor metastasis

Cancer therapy often produces anemia, which is treated with erthropoietin (EPO) to stimulate erythrocyte production. However, concerns have recently arisen that EPO treatment may promote later tumor metastasis and mortality. The mechanisms underlying such effects are unknown, but it is clear that EPO has pleiotropic effects in cell types other than hematopoietic cells. In this study, we investigated how EPO affects lymphangiogenesis and lymph node tumor metastasis in mouse models of breast cancer and melanoma. In these models, EPO increased lymph node lymphangiogenesis and lymph node tumor metastasis in a manner associated with increased migration, capillary-like tube formation, and dose- and time-dependent proliferation of human lymphatic endothelial cells. EPO increased sprouting of these cells in a thoracic duct lymphatic ring assay. These effects were abrogated by cotreatment with specific inhibitors of phosphoinositide 3-kinase or mitogen-activated protein kinase, under conditions in which EPO increased Akt and extracellular signal-regulated kinase 1/2 phosphorylation. Intraperitoneal administration of EPO stimulated peritoneal lymphangiogenesis, and systemic treatment of EPO increased infiltration of CD11b(+) macrophages in tumor-draining lymph nodes. Finally, EPO increased VEGF-C expression in lymph node-derived CD11b(+) macrophages as well as in bone marrow-derived macrophages in a dose- and time-dependent manner. Our results establish that EPO exerts a powerful lymphangiogenic function and can drive both lymph node lymphangiogenesis and nodal metastasis in tumor-bearing animals.

Lymphangiogenesis in post-natal tissue remodeling: lymphatic endothelial cell connection with its environment

The main physiological function of the lymphatic vasculature is to maintain tissue fluid homeostasis. Lymphangiogenesis or de novo lymphatic formation is closely associated with tissue inflammation in adults (i.e. wound healing, allograft rejection, tumor metastasis). Until recently, research on lymphangiogenesis focused mainly on growth factor/growth factor-receptor pathways governing this process. One of the lymphatic vessel features is the incomplete or absence of basement membrane. This close association of endothelial cells with the underlying interstitial matrix suggests that cell-matrix interactions play an important role in lymphangiogenesis and lymphatic functions. However, the exploration of interaction between extracellular matrix (ECM) components and lymphatic endothelial cells is in its infancy. Herein, we describe ECM-cell and cell-cell interactions on lymphatic system function and their modification occurring in pathologies including cancer metastasis.

VEGF-C promotes the development of esophageal cancer via regulating CNTN-1 expression

Vascular endothelial growth factor C (VEGF-C) is a key regulator of angiogenesis and lymphangiogenesis. VEGF-C is also implicated in the development of esophageal cancer. We investigated the mRNA levels of VEGF-C and its receptors in 38 esophageal squamous cell carcinoma specimens (ESCCs) and matched adjacent normal esophageal tissues via real-time PCR. The mRNA levels of VEGF-C, VEGFR-2 and VEGFR-3 were significantly upregulated in ESCCs versus respective side normal tissues. To explore the influence of VEGF-C on esophageal cancer progression, the expression of VEGF-C was manipulated in esophageal cancer cell lines TE-1 and Eca-109. VEGF-C transcription, translation and secretion were significantly enhanced in cells stably transfected with a VEGF-C overexpression vector or attenuated in VEGF-C shRNA-transfected cell lines. In vitro, TE-1 cells stably transfected with a VEGF-C overexpression vector exhibited an increased rate of cell proliferation, migration and focus formation, whereas knockdown of VEGF-C inhibited cell proliferation, migration and focus formation. Similar results were obtained for Eca-109 cells. VEGF-C mediated biological function through transcription of CNTN-1, which is implicated in tumor invasion and metastasis. The expression of VEGF-C was correlated with that of CNTN-1 and cell proliferation and migration induced by VEGF-C were reversed by silencing of CNTN-1. In addition, nude mice inoculated with VEGF-C shRNA-transfected cells exhibited a significantly decreased tumor size in vivo via reduced VEGFR-2 and VEGFR-3 phosphorylation and microvessel formation. VEGF-C upregulation may be involved in esophageal tumor progression. Vector-based RNA interference (RNAi) targeting VEGF-C is a potential therapeutic method for human esophageal carcinoma.

MAPK and PI3K signalling differentially regulate angiogenic and lymphangiogenic cytokine secretion in squamous cell carcinoma of the head and neck

Vascular endothelial growth factors (VEGF-C and VEGF-A) play important roles in tumour-induced lymphangiogenesis and angiogenesis, respectively, key processes implicated in promoting tumour growth and metastatic spread. Previous work from our laboratory has shown that EGFR overexpression in squamous carcinomas of the head and neck (SCCHN) is linked to high levels of VEGF-A and VEGF-C (but low levels of VEGF-D) and is associated with poor prognosis. The present study explored the signalling pathways regulating the induction of VEGF-C and VEGF-A in the SCCHN cell lines CAL 27 and Detroit 562. The addition of exogenous EGF induced the expression of VEGF-C and VEGF-A in a concentration-dependent manner and this was blocked by a selective EGFR inhibitor, gefitinib. In both cell lines stimulated with endogenous or exogenous ligand, inhibition of MEK1/2 (with U0126 or PD98059) or PI3K (with PI-103 or LY294002) resulted in a marked reduction of EGFR-induced VEGF-A expression, whereas exogenous EGF-induced VEGF-C upregulation was blocked by inhibitors of MEK but not PI3K. Inhibition of p38 MAPK suppressed EGF-induced VEGF-C upregulation in CAL 27 cells, but inhibited EGF-induced VEGF-A upregulation in Detroit 562. Taken together, our evidence suggests that both endogenous and exogenous EGFR activation induces VEGF-A expression requiring both PI3K and MAPK signalling whereas VEGF-C expression is dependent on MAPK, but not the PI3K or mTOR pathways in SCCHN cell lines. p38 MAPK appears to be differentially linked to either VEGF-A or VEGF-C regulation in different cellular contexts.

A phase II study of pazopanib in patients with recurrent or metastatic invasive breast carcinoma: a trial of the Princess Margaret Hospital phase II consortium

PURPOSE

Angiogenesis is an important hallmark of breast cancer growth and progression. Pazopanib, an oral small molecule inhibitor of vascular endothelial growth factor receptor, platelet-derived growth factor receptor, and KIT, has activity across a range of solid tumors. We evaluated the activity of single-agent pazopanib in recurrent or metastatic breast cancer (MBC).

PATIENTS AND METHODS

Patients with recurrent breast cancer or MBC, treated with up to two prior lines of chemotherapy, were eligible to receive pazopanib, 800 mg daily until progression. The primary endpoint was the objective response rate as measured by Response Evaluation Criteria in Solid Tumors. Secondary endpoints included time to progression, the stable disease rate, and toxicity. Using a two-stage design, confirmed response in three of 18 patients was required to proceed to stage 2.

RESULTS

Twenty evaluable patients were treated, with a median age of 56 years; 70% were estrogen receptor positive, all were human epidermal growth factor receptor 2 negative. The majority had one or two prior lines of chemotherapy. One patient (5%) had a partial response, 11 (55%) had stable disease (SD) [four (20%) with SD > or = 6 months], and seven (35%) had progressive disease as their best response. One (5%) was not evaluable. The median time to progression was 5.3 months. Pazopanib did not cause significant severe toxicity aside from grade 3-4 transaminitis, hypertension, and neutropenia in three patients each (14% each) and grade 3 gastrointestinal hemorrhage in one patient (5%).

CONCLUSION

Pazopanib provides disease stability in advanced breast cancer. The activity seen is comparable with that of other antiangiogenic agents in this setting. Pazopanib may be of interest for future studies in breast cancer, including in combination with other systemic agents.

Role of lymphangiogenesis in lung cancer

Lung cancer represents one of the most frequent causes of death due to neoplastic disease in Poland and around the world. The high mortality which accompany neoplastic diseases used to be ascribed mainly to dissemination of cancerous cells. Studies on animal models suggest that tumour lymphangiogenesis represents the principal factor in the process of metastases formation. Lymphangiogenesis involves a process of formation of new lymphatic vessels from already existing lymphatic capillaries. Lymphangiogenesis is stimulated by vascular endothelial growth factors (VEGF) and other, recently reported factors, such as, e.g., cyclooxygenase 2, fibroblast growth factor 2, angiopoetin-1 and the insulin-resembling growth factor. In lymphangiogenesis a key role is played by neutropilin 2 or podoplanin and this promoted development of studies on lymphangiogenesis. Activation of VEGF-C/VEGF-D/VEGFR-3 axis increases motility and invasiveness of neoplastic cells, promotes development of metastases in several types of tumours such as, e.g., lung cancer, mammary carcinoma, cancers of the neck, prostate and large intestine. In recent years lymphangiogenesis provided topic of many studies. A positive correlation was detected between expressions of VEGF-C/D and VEGFR-3 in non-small cell lung cancer. In patients with lung cancer with high expression of VEGF-C a markedly abbreviated survival was noted. Positive correlation was detected between expression of VEGF-C and VEGF-D on one hand and expression of LYVE-1 on the other in sentinel lymph nodes with metastases of neoplastic cells in patients with non-small cell lung cancer. Also, high density of lymphatic vessels and high density of intraneoplastic microvessels proved to be independent poor prognostic indices in patients with non-small cell lung cancer. Extensive hope is linked to studies on inhibitors of lymphangiogenesis, which may improve results of treatment also in tumour patients.

Correlations of RUNX3 and RASSF1A promoter hypermethylation with the progression and metastasis of gastric carcinoma

AIM: To investigate the clinical significance of runt-related transcription factor 3 (RUNX3) and Ras association domain family 1A (RASSF1A) promoter methylation in human gastric cancer.

METHODS: The mRNA expression and methylation of RUNX3, and RASSF1A in 62 gastric cancer specimens and 56 adjacent normal tissue specimens were detected by reverse transcription-polymerase chain reaction (RT-PCR) and methylation-specific PCR (MSP), respectively. The expression of VEGF protein was measured by immunohistochemistry in methylation-positive and -negative cancer tissue specimens and 20 normal gastric tissue specimens.

RESULTS: The mRNA expression levels of RUNX3 and RASSF1A in gastric cancer were lower than those in normal gastric tissue (0.629 ± 0.461 vs 0.893 ± 0.543 and 0.653 ± 0.476 vs 0.858 ± 0.581, respectively; both P < 0.05). The positive rates of RUNX3 and RASSF1A methylation were significantly higher in gastric cancer tissue specimens than in normal control ones (69.4% vs 26.8% and 66.1% vs 23.2%, respectively; both P < 0.01). The expression levels of RUNX3 and RASSF1A mRNAs were lower in methylation-positive cancer tissue specimens than in methylation-negative ones (P < 0.05). Neither RUNX3 nor RASSF1A promoter methylation were correlated with sex, age, tumor size, tumor differentiation degree, and Lauren classification. However, RASSF1A methylation was related with TNM stage and depth of infiltration, and RUNX3 methylation was associated with lymph node metastasis, vascular invasion and TNM stage. The positive rate of VEGF protein expression in RUNX3 methylation-positive gastric cancer specimens was significantly higher than that in RUNX3 methylation-negative ones (86.0% vs 57.9%, P < 0.05).

CONCLUSION: Aberrant RUNX3 and RASSF1A promoter methylation may lead to down-regulation of the two genes in GC and is therefore involved in the progression of the disease. RUNX3 promoter methylation may participate in the vascular/lymphatic metastasis of GC.

Lymphangiogenesis and lymphatic metastasis in breast cancer

Lymphatic metastasis is the main prognostic factor for survival of patients with breast cancer and other epithelial malignancies. Mounting clinical and experimental data suggest that migration of tumor cells into the lymph nodes is greatly facilitated by lymphangiogenesis, a process that generates new lymphatic vessels from pre-existing lymphatics with the aid of circulating lymphatic endothelial progenitor cells. The key protein that induces lymphangiogenesis is vascular endothelial growth factor receptor-3 (VEGFR-3), which is activated by vascular endothelial growth factor-C and -D (VEGF-C and VEGF-D). These lymphangiogenic factors are commonly expressed in malignant, tumor-infiltrating and stromal cells, creating a favorable environment for generation of new lymphatic vessels. Clinical evidence demonstrates that increased lymphatic vessel density in and around tumors is associated with lymphatic metastasis and reduced patient survival. Recent evidence shows that breast cancers induce remodeling of the local lymphatic vessels and the regional lymphatic network in the sentinel and distal lymph nodes. These changes include an increase in number and diameter of tumor-draining lymphatic vessels. Consequently, lymph flow away from the tumor is increased, which significantly increases tumor cell metastasis to draining lymph nodes and may contribute to systemic spread. Collectively, recent advances in the biology of tumor-induced lymphangiogenesis suggest that chemical inhibitors of this process may be an attractive target for inhibiting tumor metastasis and cancer-related death. Nevertheless, this is a relatively new field of study and much remains to be established before the concept of tumor-induced lymphangiogenesis is accepted as a viable anti-metastatic target. This review summarizes the current concepts related to breast cancer lymphangiogenesis and lymphatic metastasis while highlighting controversies and unanswered questions.

Prognostic impact of lymphatic invasion in patients with node-negative gastric cancer

BACKGROUND AND OBJECTIVES

This study investigated the prognostic impact of lymphatic invasion on the outcome of patients with node-negative gastric cancer.

METHODS

A total of 828 patients with node-negative gastric cancer who underwent curative gastrectomy were reviewed retrospectively. The clinicopathological features and prognoses of patients with lymphatic invasion were compared to those of patients without such invasion.

RESULTS

The total rate of lymphatic invasion was 18.2% in node-negative gastric cancers, with a significant difference between early gastric cancers (9.8%) and advanced gastric cancers (49.2%). The presence of lymphatic invasion correlated significantly with tumor location, size and depth of tumor (P < 0.01). Lymphatic invasion was significantly associated with a poorer overall survival in node-negative gastric cancer patients on univariate analysis (P < 0.001) as well as multivariate analysis (P < 0.01).

CONCLUSIONS

Lymphatic invasion provides additional useful information that could be applied to identify patients at high risk for recurrence who might be candidates for adjuvant therapies in patients with node-negative gastric cancers.

Tumor lymphatics

In this article we survey more than three centuries of observation and research into tumor-associated lymphatic vessels, and their role in the metastatic spread of cancer. This historical overview documents how questions regarding tumor lymphatics have been central to concepts about the process of metastasis, and how this has subsequently influenced the clinical treatment of cancer. In turn, we show how analysis of the efficacy of these treatments has challenged long-standing notions regarding the tumor lymphatics. Starting with the discovery of VEGFR-3 and its ligands VEGF-C and VEGF-D, we also review how the rapid developments over the last 15 years in the molecular analysis of the lymphatic system and in particular lymphangiogenesis have contributed to this debate. Finally we speculate on how apparently paradoxical bodies of evidence regarding the role of tumor lymphatics in determining patterns of metastatic spread might be reconciled.

Prognostic significance of VEGF-C expression in correlation with COX-2, lymphatic microvessel density, and clinicopathologic characteristics in human non-small cell lung cancer

Lung cancer is one of the most lethal cancers in China because of high incidence and high mortality. Cyclooxygenase-2 (COX-2) and vessel endothelial growth factor C (VEGF-C) were found to play an important role in lymphangiogenesis of malignant tumors. In this study, we investigated whether lymphatic microvessel density (LMVD) is related to the prognosis in non-small cell lung cancer (NSCLC) patients, and the expressions of COX-2 and VEGF-C so as to determine the possible role of COX-2 and VEGF-C in NSCLC lymphangiogenesis. Sixty-five formalin-fixed paraffin embedded tissue samples of NSCLC were evaluated for COX-2 and VEGF-C by immunohistochemical staining. To assess tumor lymphangiogenesis, LMVD was determined by immunohistochemical staining of VEGFR-3 polyclonal antibody. The relationship among COX-2 and VEGF-C expression, LMVD, and clinicopathologic parameters was analyzed. Among the 65 samples, high LMVD was significantly associated with lymph node metastasis and poor survival. Multivariate survival analysis showed that LMVD value and lymph node metastasis were independent prognostic factors. The expression level of COX-2 and VEGF-C was significantly higher than those of the adjacent tissues. COX-2 and VEGF-C expressions in NSCLC significantly correlated with lymph node metastasis, but not with patient gender, age, tumor size, or tumor, nodes, metastasis classification stage. The mean LMVD value of COX-2- or VEGF-C-positive tumors was higher than that of COX-2- or VEGF-C-negative tumors. A significant correlation was found between the expressions of COX-2 and VEGF-C. This study suggests that LMVD may be one of the important prognostic factors for NSCLC patients. VEGF-C might play an important role in the COX-2 lymphangiogenic pathway. COX-2 and VEGF-C may play an important role in tumor progression by stimulating lymphangiogenesis. The inhibition of lymphangiogenesis, COX-2, or VEGF-C activity may have an important therapeutic benefit in the control of NSCLC.