Lymphangiogenesis: A new player in cancer progression

CEACAM1 increased the lymphangiogenesis through miR-423-5p and NF- kB in Non-Small Cell Lung Cancer

Background

Lung cancer causes significant mortality, with invasion and metastasis being the main features that cause most cancer deaths. Lymph node metastasis is the primary metastatic route in non-small cell carcinoma (NSCLC) and influences the staging and prognosis of NSCLC. Cumulative studies have reported that Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) is involved in the progression of various cancers. However, few studies have discussed the function of CEACAM1 in lymphangiogenesis in NSCLC. Here, we examined how CEACAM1 influences lymphangiogenesis in NSCLC.

Methods

A total of 30 primary squamous cell carcinoma (LUSC) patients diagnosed with LN metastasis were prospectively selected. LUSC tumor tissues, para-cancerous tissues, and positive lymph node tissues were harvested. The expression and subcellular location of CEACAM1, CD31, and LVYE1 in clinical samples were detected by immunohistochemistry. Next, the CEACAM1 and hsa-miR-423-5p expressions were detected by qPCR. The protein expression of lymphangiogenesis-associated proteins and critical cytokines of the NF-κB pathway in HDLECs was detected by Western blot. A tube formation assay was performed to detect the lymphangiogenesis in different groups. The interaction between CEACAM1 and hsa-miR-423-5p was verified using a dual luciferase assay.

Results

CEACAM1 was found to be a potential gene associated with lung cancer prognosis. It was positively correlated with angiogenesis and lymphangiogenesis. Then, we detected the function of CEACAM1 in lymphangiogenesis and found that CEACAM1 promoted lymphangiogenesis. hsa-miR-423-5p overexpression inhibited lymphangiogenesis via targeting CEACAM1. Finally, we observed that CEACAM1 can activate the NF-κB pathway and, therefore, promote lymphangiogenesis.

Conclusion

We found that CEACAM1 enhanced lymphangiogenesis in NSCLC via NF-kB activation and was repressed by miR-423-5p. This suggests the value of CEACAM1 as a new therapeutic marker in NSCLC.

Advances in lymphatic metastasis of non-small cell lung cancer

Lung cancer is a deeply malignant tumor with high incidence and mortality. Despite the rapid development of diagnosis and treatment technology, abundant patients with lung cancer are still inevitably faced with recurrence and metastasis, contributing to death. Lymphatic metastasis is the first step of distant metastasis and an important prognostic indicator of non-small cell lung cancer. Tumor-induced lymphangiogenesis is involved in the construction of the tumor microenvironment, except promoting malignant proliferation and metastasis of tumor cells, it also plays a crucial role in individual response to treatment, especially immunotherapy. Thus, this article reviews the current research status of lymphatic metastasis in non-small cell lung cancer, in order to provide some insights for the basic research and clinical and translational application in this field.

Targeting Sphingosine-1-Phosphate Signaling in Breast Cancer

In recent years, newly emerging therapies, such as immune checkpoint inhibitors and antibody-drug conjugates, have further improved outcomes for breast cancer patients. However, recurrent and metastatic breast cancer often eventually develops resistance to these drugs, and cure is still rare. As such, the development of new therapies for refractory breast cancer that differ from conventional mechanisms of action is necessary. Sphingosine-1-phosphate (S1P) is a key molecule with a variety of bioactive activities, including involvement in cancer cell proliferation, invasion, and metastasis. S1P also contributes to the formation of the cancer microenvironment by inducing surrounding vascular- and lymph-angiogenesis and regulating the immune system. In this article, we outline the basic mechanism of action of S1P, summarize previous findings on the function of S1P in cancer cells and the cancer microenvironment, and discuss the clinical significance of S1P in breast cancer and the therapeutic potential of targeting S1P signaling.

CircVPRBP inhibits nodal metastasis of cervical cancer by impeding RACK1 O-GlcNAcylation and stability

Lymph node (LN) metastasis is one of the most malignant clinical features in patients with cervical cancer (CCa). Understanding the mechanism of lymph node metastasis will provide treatment strategies for patients with CCa. Circular RNAs (circRNA) play a critical role in the development of human cancers. However, the role and mechanism of circRNAs in lymph node metastasis remain largely unknown. Here, it is reported that loss expression of circRNA circVPRBP was closely associated with LN metastasis and poor survival of CCa patients. In vitro and in vivo assays showed that circVPRBP overexpression notably inhibited lymphangiogenesis and LN metastasis, whereas RfxCas13d mediated silencing of circVPRBP promoted lymphangiogenesis and the ability of the cervical cancer cells to metastasize to the LNs. Mechanistically, circVPRBP could bind to RACK1 and shield the S122 O-GlcNAcylation site to promote RACK1 degradation, resulting in inhibition of Galectin-1 mediated lymphangiogenesis and LN metastasis in CCa. Taken together, the results demonstrate that circVPRBP is a potential prognostic biomarker and a novel therapeutic target for LN metastasis in CCa patients.

Lymphatic Vessel Regression and Its Therapeutic Applications: Learning From Principles of Blood Vessel Regression

Aberrant lymphatic system function has been increasingly implicated in pathologies such as lymphedema, organ transplant rejection, cardiovascular disease, obesity, and neurodegenerative diseases including Alzheimer's disease and Parkinson's disease. While some pathologies are exacerbated by lymphatic vessel regression and dysfunction, induced lymphatic regression could be therapeutically beneficial in others. Despite its importance, our understanding of lymphatic vessel regression is far behind that of blood vessel regression. Herein, we review the current understanding of blood vessel regression to identify several hallmarks of this phenomenon that can be extended to further our understanding of lymphatic vessel regression. We also summarize current research on lymphatic vessel regression and an array of research tools and models that can be utilized to advance this field. Additionally, we discuss the roles of lymphatic vessel regression and dysfunction in select pathologies, highlighting how an improved understanding of lymphatic vessel regression may yield therapeutic insights for these disease states.

Intratumoral lymphatic endothelial cell infiltration reflecting lymphangiogenesis is counterbalanced by immune responses and better cancer biology in the breast cancer tumor microenvironment

Lymphangiogenesis, the generation of new lymphatic vessels from existing ones, results from the dynamic interactions of lymphatic endothelial cells and the tumor microenvironment (TME). It is well known that lymphangiogenesis occurs during the initial stage of metastasis in various types of malignant tumors. However, it is currently not used as a biomarker partially because gold standard method to quantify it is labor and cost intensive. We hypothesized that the quantity of intratumoral lymphatic endothelial cells (iLECs) in the TME is an indicator of lymphangiogenesis and a predictor of metastatic potential and overall survival in breast cancer. We analyzed a total of 4145 breast cancer patients from the Cancer Genome Atlas (TCGA) and GSE96058 by quantifying their iLECs using the xCell algorithm, and correlated these scores with patient survival, tumor grade, and cancer stage. We also assessed various pro- and anti-cancer gene sets for each tumor to characterize tumor behavior and aggressiveness. As we expected, high-iLEC breast cancer demonstrated enriched lymphoangiogenesis and angiogenesis gene sets and was associated with increased expressions of related genes. Also enriched were inflammatory response and immune response-related gene sets; IL2/STAT5 pathway, IL6/JAK/STAT3 pathway, TNFα pathway, allograft rejection, and complement as well as cancer stemness related gene sets like Notch signaling, Hedgehog signaling, epithelial mesenchymal transition, and Wnt beta-catenin signaling. Tumors with high-iLEC showed higher proportions of stromal cells and fewer anti-cancer immune cells. On the other hand, iLEC score did not correlate with patient survival or lymph node metastasis. Surprisingly, breast cancers with fewer iLECs demonstrated enriched E2F Targets, G2M Checkpoint, MYC Targets v1, and MTORC1 signaling which are cancer cell proliferation-related gene sets and exhibited an abundance of pro-cancer immune cells. The amount of iLEC correlated inversely with Ki67 expression and histological grade, which is in agreement that low-iLEC breast cancer was associated with enhanced cancer cell proliferation. In conclusion, while iLECs can be used as a surrogate for lymphangiogenesis in breast cancer, low-iLEC tumors also exhibit features which correspond to aggressive tumor biology, which may explain why the amount of iLECs was not associated with patient survival in our cohorts.

Sentinel Lymph Node Metastasis on Clinically Negative Patients: Preliminary Results of a Machine Learning Model Based on Histopathological Features

The reported incidence of node metastasis at sentinel lymph node biopsy is generally low, so that the majority of women underwent unnecessary invasive axilla surgery. Although the sentinel lymph node biopsy is time consuming and expensive, it is still the intra-operative exam with the highest performance, but sometimes surgery is achieved without a clear diagnosis and also with possible serious complications. In this work, we developed a machine learning model to predict the sentinel lymph nodes positivity in clinically negative patients. Breast cancer clinical and immunohistochemical features of 907 patients characterized by a clinically negative lymph node status were collected. We trained different machine learning algorithms on the retrospective collected data and selected an optimal subset of features through a sequential forward procedure. We found comparable performances for different classification algorithms: on a hold-out training set, the logistics regression classifier with seven features, i.e., tumor diameter, age, histologic type, grading, multiplicity, in situ component and Her2-neu status reached an AUC value of 71.5% and showed a better trade-off between sensitivity and specificity (69.4 and 66.9%, respectively) compared to other two classifiers. On the hold-out test set, the performance dropped by five percentage points in terms of accuracy. Overall, the histological characteristics alone did not allow us to develop a support tool suitable for actual clinical application, but it showed the maximum informative power contained in the same for the resolution of the clinical problem. The proposed study represents a starting point for future development of predictive models to obtain the probability for lymph node metastases by using histopathological features combined with other features of a different nature.

Colon Cancer Progression Is Reflected to Monotonic Differentiation in Gene Expression and Pathway Deregulation Facilitating Stage-specific Drug Repurposing

BACKGROUND/AIM

Colon cancer is one of the most common cancer types and the second leading cause of death due to cancer. Many efforts have been performed towards the investigation of molecular alterations during colon cancer progression. However, the identification of stage-specific molecular markers remains a challenge. The aim of this study was to develop a novel computational methodology for the analysis of alterations in differential gene expression and pathway deregulation across colon cancer stages in order to reveal stage-specific biomarkers and reinforce drug repurposing investigation.

MATERIALS AND METHODS

Transcriptomic datasets of colon cancer were used to identify (a) differentially expressed genes with monotonicity in their fold changes (MEGs) and (b) perturbed pathways with ascending monotonic enrichment (MEPs) related to the number of the participating differentially expressed genes (DEGs), across the four colon cancer stages. Through an in silico drug repurposing pipeline we identified drugs that regulate the expression of MEGs and also target the resulting MEPs.

RESULTS

Our methodology highlighted 15 MEGs and 32 candidate repurposed drugs that affect their expression. We also found 51 MEPs divided into two groups according to their rate of DEG content alteration across colon cancer stages. Focusing on the target MEPs of the highlighted repurposed drugs, we found that one of them, the neuroactive ligand-receptor interaction, was targeted by the majority of the candidate drugs. Moreover, we observed that two of the drugs (PIK-75 and troglitazone) target the majority of the resulting MEPs.

CONCLUSION

These findings highlight significant genes and pathways that can be used as stage-specific biomarkers and facilitate the discovery of new potential repurposed drugs for colon cancer. We expect that the computational methodology presented can be applied in a similar way to the analysis of any progressive disease.

Inhibition of NADPH oxidase 4 attenuates lymphangiogenesis and tumor metastasis in breast cancer

Lymphangiogenesis is thought to contribute to promote tumor cells to enter lymphatic vessels and plant at a secondary site. Endothelial cells are the cornerstone of the generation of new lymphatic vessels. NADPH oxidase 4 (Nox4) is the most abundant one of NADPH oxidases in endothelial cells and the most studied one in relevance with cancer. Our purpose is to analyze the relationship between Nox4 and lymphangiogenesis and find out whether the newborn lymphatic vessels lead to cancer metastasis. We first explored the expression of Nox4 in lymphatic endothelial cells of primary invasive breast tumors and human normal mammary glands using GEO databases and found that Nox4 was upregulated in primary invasive breast tumors samples. In addition, its high expression correlated with lymph node metastasis in breast cancer patients. Nox4 could increase the tube formation and lymphatic vessel sprouting in a three-dimensional setting. In vivo, inhibition of Nox4 in 4T1 tumor-bearing mice could significantly decrease the tumor lymphangiogenesis and metastasis. Nox4 may increase tumor lymphangiogenesis via ROS/ERK/CCL21 pathway and attract CCR7-positive breast cancer cells to entry lymphatic vessels and distant organs. In conclusion, our results show that Nox4 is a factor that promotes lymphangiogenesis and is a potential target of antitumor metastasis.

Compelling Long-Term Results for Liver Resection in Early Cholangiocarcinoma

Surgery for intrahepatic cholangiocarcinoma (iCCA) is associated with a high rate of recurrence even after complete resection. To achieve acceptable results, preoperative patient selection is crucial. Hence, we aimed to identify preoperative characteristics with prognostic value focusing on certain radiological features. Patients who underwent hepatectomy for iCCA between 2010 and 2020 at University Hospital, RWTH Aachen were included. Kaplan–Meier and Cox regressions were applied for survival analysis and associations of overall survival (OS) and recurrence-free survival (RFS) with clinical/radiological characteristics, respectively. Based on radiological features patients were stratified into three groups: single nodule ≤ 3 cm, single nodule > 3 cm, and ≥2 nodules. Analysis of 139 patients revealed a mean OS of 142 months for those with a single nodule ≤3 cm, median OS of 28 months with a single nodule >3 cm, and 19 months with ≥2 nodules, respectively. Multivariable analyses based on preoperative characteristics showed the radiological stratification to be independently associated with OS (HR (hazard ratio) = 4.25 (1 nodule, >3 cm), HR = 5.97 (≥2 nodules), p = 0.011), RFS (HR = 4.18 (1 nodule, >3 cm), and HR = 11.07 (≥2 nodules), p = 0.001). In conclusion, patients with single iCCA ≤3 cm show compelling OS and RFS. Basic radiological features (e.g., nodule size, number) are prognostic for patients undergoing surgery and useful in preoperative patient selection.

Clinical relevance of tumor microenvironment: immune cells, vessels, and mouse models

The tumor microenvironment (TME) plays a crucial role in tumor progression, therapeutic response, and patient outcomes. TME includes immune cells, blood and lymphatic vessels, and so on. There are anti-cancer and pro-cancer immune cells. In general, infiltration of anti-cancer immune cells, such as cytotoxic T cells (CTLs), is associated with a favorable patient prognosis. In contrast, infiltration of pro-cancer immune cells, such as regulatory T cells (Tregs), tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs), is associated with a worse prognosis. However, some immune cells, which play an ambivalent role in cancer immunity, have demonstrated contradictory impacts on patient prognosis. Blood and lymphatic vessels play crucial roles in TME not only as delivery and draining systems of fluid and molecules, but also allowing cancer cells access to systematic circulation to metastasize. Angiogenesis promotes cancer aggressiveness and is associated with a worse prognosis. Its targeted therapy shows a benefit in some cancers, however, because the target can vary by caner type, a benefit of anti-angiogenesis therapy is limited in the current standard of care. Lymphangiogenesis plays a role in lymph node metastasis, thus, it is associated with a poor prognosis in some cancers. To study TME, the mouse model is one of the most commonly used tools. The choice of appropriate mouse model depends on the hypothesis being tested and the scientific question being asked. Here, we review recent studies that investigated the clinical relevance of TME components and introduce mouse models to study TME.

Lymphovascular invasion in breast cancer is associated with gene expression signatures of cell proliferation but not lymphangiogenesis or immune response

BACKGROUND

While the prognostic relevance of lymphovascular invasion (LVI) in breast cancer is well known, its molecular biology is poorly understood. We hypothesized that pathologically determined LVI reflects molecular features of tumors and can be discerned from their genomic and transcriptomic profiles.

METHODS

LVI status and Nottingham histological scores of primary breast tumors of The Cancer Genome Atlas (TCGA) project were assessed from pathology reports; other clinical and molecular data were obtained from TCGA data portals and publications. Two independent datasets (GSE5460 and GSE7849) were combined and used for validation.

RESULTS

LVI status was determinable for 639 and 196 cases of the TCGA and validation cohorts, among whom LVI incidence was 37.8% and 37.2%, respectively. LVI was associated with high tumor Ki67 expression, advanced pathologic stage, and high Nottingham scores. LVI-positive cases had worse overall and progression-free survival regardless of cancer subtype. Surprisingly, in both cohorts, LVI was not associated with lymphangiogenesis or lymphatic vessel density as estimated from tumor expression of lymphatic endothelium-associated genes. LVI-positive tumors had higher genome copy number aberrations, aneuploidy, and homologous recombination defects, but not single-nucleotide variations or intra-tumor genome heterogeneity. Tumor immune cell composition and cytolytic activity was not associated with LVI status. On the other hand, expression of cell proliferation-related genes was significantly increased in LVI-positive tumors.

CONCLUSION

Our study suggests that breast cancer with LVI is a highly proliferative cancer, and it does not correlate with gene expression markers for lymphangiogenesis or immune response.

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.

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The prognostic role of lymphovascular invasion and lymph node metastasis in perihilar and intrahepatic cholangiocarcinoma

INTRODUCTION

Cholangiocellular carcinoma (CCA) is an aggressive malignancy with a dismal prognosis. Among curative treatment options for CCA, radical surgical resection with extrahepatic bile duct resection, hepatectomy and en-bloc lymphadenectomy are considered the mainstay of curative therapy. Here, we aimed to identify prognostic markers of clinical outcome in CCA-patients who underwent surgical resection in curative intent.

MATERIAL AND METHODS

Between 2011 and 2016, 162 patients with CCA (perihilar CCA (pCCA): n = 91, intrahepatic CCA (iCCA): n = 71) underwent surgery in curative intent at our institution. Preoperative characteristics, perioperative data and oncological follow-up were obtained from a prospectively managed institutional database. The associations of overall- (OS) and disease-free-survival (DFS) with clinico-pathological characteristics were assessed using univariate and multivariable cox regression analyses.

RESULTS

The median OS and DFS were 38 and 36 months for pCCA and 25 and 13 months for iCCA, respectively. Lymphovascular invasion (LVI) and lymph node metastasis as well as surgical complications as assessed by the comprehensive complication index (CCI) and tumor grading were independently associated with OS for the pCCA (LVI; RR = 2.36, p = 0.028; CCI; RR = 1.04, p < 0.001) and iCCA cohorts (N-category; RR = 3.21, p = 0.040; tumor grading; RR = 3.75, p = 0.013; CCI, RR = 4.49, p = 0.010), respectively. No other clinical variable including R0-status and Bismuth classification was associated with OS.

CONCLUSION

Major liver resections for CCA are feasible and safe in experienced high-volume centers. Lymph node metastasis and LVI are associated with adverse clinical outcome, supporting the role of systematic lymphadenectomy. The assessment of LVI may be useful in identifying high-risk patients for adjuvant treatment strategies.

Phospho-Sphingosine Kinase 1 Expression in Lymphatic Spread of Esophageal Squamous Cell Carcinoma

BACKGROUND

Lymphatic spread is the main mode of progression of esophageal squamous cell carcinoma (ESCC). Sphingosine-1-phosphate (S1P) is a pleiotropic bioactive lipid mediator, which produced by sphingosine kinase 1 (SphK1) activated by phosphorylation. The SphK1-S1P axis has a crucial role in lymphangiogenesis. However, the significance of phospho-SphK1 (pSphK1) in the progression of ESCC has not been fully investigated.

MATERIALS AND METHODS

We evaluated pSphK1 expression in 92 surgically resected tumor tissues of ESCC by the immunohistochemistry. Fifty-nine (64%) patients with moderate or strong expression and 33 (36%) with negative or weak expression were classified in the pSphK1-high and pSphK1-low groups, respectively.

RESULTS

Higher pathological N category (pN) was more frequently observed in the pSphK1-high group (P < 0.01). The median number of lymph node metastasis (pSphK1-high: 2 versus pSphK1-low: 0; P < 0.01), the proportion of patients with lymphatic invasion (69% versus 18%; P < 0.01) and that with intramural metastasis (27% versus 3%; P < 0.01) were significantly higher in the pSphK1-high group. The presence of lymphatic invasion (odds ratio [OR] 5.63; P < 0.01) and pN1-3 (OR 3.26; P = 0.04) were independently associated with high pSphK1 expression. The 5-y overall survival rate of the pSphK1-high group was significantly lower than that of the pSphK1-low group (50.8% versus 67.3%; P = 0.01). High pSphK1 expression was not identified as a significant independent prognostic factor.

CONCLUSIONS

We provide the first evidence of the association between high expression of pSphK1 and both lymphatic spread and patient outcomes in ESCC.

Ovarian Tumor Microenvironment Signaling: Convergence on the Rac1 GTPase

The tumor microenvironment for epithelial ovarian cancer is complex and rich in bioactive molecules that modulate cell-cell interactions and stimulate numerous signal transduction cascades. These signals ultimately modulate all aspects of tumor behavior including progression, metastasis and therapeutic response. Many of the signaling pathways converge on the small GTPase Ras-related C3 botulinum toxin substrate (Rac)1. In addition to regulating actin cytoskeleton remodeling necessary for tumor cell adhesion, migration and invasion, Rac1 through its downstream effectors, regulates cancer cell survival, tumor angiogenesis, phenotypic plasticity, quiescence, and resistance to therapeutics. In this review we discuss evidence for Rac1 activation within the ovarian tumor microenvironment, mechanisms of Rac1 dysregulation as they apply to ovarian cancer, and the potential benefits of targeting aberrant Rac1 activity in this disease. The potential for Rac1 contribution to extraperitoneal dissemination of ovarian cancer is addressed.

Generation of sphingosine-1-phosphate is enhanced in biliary tract cancer patients and is associated with lymphatic metastasis

Lymphatic metastasis is known to contribute to worse prognosis of biliary tract cancer (BTC). Recently, sphingosine-1-phosphate (S1P), a bioactive lipid mediator generated by sphingosine kinase 1 (SPHK1), has been shown to play an important role in lymphangiogenesis and lymph node metastasis in several types of cancer. However, the role of the lipid mediator in BTC has never been examined. Here we found that S1P is elevated in BTC with the activation of ceramide-synthetic pathways, suggesting that BTC utilizes SPHK1 to promote lymphatic metastasis. We found that S1P, sphingosine and ceramide precursors such as monohexosyl-ceramide and sphingomyelin, but not ceramide, were significantly increased in BTC compared to normal biliary tract tissue using LC-ESI-MS/MS. Utilizing The Cancer Genome Atlas cohort, we demonstrated that S1P in BTC is generated via de novo pathway and exported via ABCC1. Further, we found that SPHK1 expression positively correlated with factors related to lymphatic metastasis in BTC. Finally, immunohistochemical examination revealed that gallbladder cancer with lymph node metastasis had significantly higher expression of phospho-SPHK1 than that without. Taken together, our data suggest that S1P generated in BTC contributes to lymphatic metastasis.

Potential lymphangiogenesis therapies: Learning from current antiangiogenesis therapies-A review

In recent years, lymphangiogenesis, the process of lymphatic vessel formation from existing lymph vessels, has been demonstrated to have a significant role in diverse pathologies, including cancer metastasis, organ graft rejection, and lymphedema. Our understanding of the mechanisms of lymphangiogenesis has advanced on the heels of studies demonstrating vascular endothelial growth factor C as a central pro-lymphangiogenic regulator and others identifying multiple lymphatic endothelial biomarkers. Despite these breakthroughs and a growing appreciation of the signaling events that govern the lymphangiogenic process, there are no FDA-approved drugs that target lymphangiogenesis. In this review, we reflect on the lessons available from the development of antiangiogenic therapies (26 FDA-approved drugs to date), review current lymphangiogenesis research including nanotechnology in therapeutic drug delivery and imaging, and discuss molecules in the lymphangiogenic pathway that are promising therapeutic targets.

Gefitinib Leads to Complete Resolution of Postoperative Cervical Chyloma and Chylothorax in a Lung Cancer Patient

Cervical chyloma is a not uncommon complication after neck surgery, especially following diagnostic excision of supraclavicular lymph nodes. Conservative treatment remains the standard approach but is inevitably distressful. We describe the case of a 60-year-old Asian woman who was diagnosed as having adenocarcinoma of the lung with cervical and supraclavicular node involvement. She developed persistent cervical chyle leak after excisional biopsy of the supraclavicular nodes and proved refractory to all management. Subsequent gefitinib therapy led to rapid resolution of chyloma and tumor regression. This case provided a unique experience of managing intractable postoperative chyloma in a cancer patient.

Clinical Impact of Sphingosine-1-Phosphate in Breast Cancer

Breast cancer metastasizes to lymph nodes or other organs, which determine the prognosis of patients. It is difficult to cure the breast cancer patients with distant metastasis due to resistance to drug therapies. Elucidating the underlying mechanisms of breast cancer metastasis and drug resistance is expected to provide new therapeutic targets. Sphingosine-1-phosphate (S1P) is a pleiotropic, bioactive lipid mediator that regulates many cellular functions, including proliferation, migration, survival, angiogenesis/lymphangiogenesis, and immune responses. S1P is formed in cells by sphingosine kinases and released from them, which acts in an autocrine, paracrine, and/or endocrine manner. S1P in extracellular space, such as interstitial fluid, interacts with components in the tumor microenvironment, which may be important for metastasis. Importantly, recent translational research has demonstrated an association between S1P levels in breast cancer patients and clinical outcomes, highlighting the clinical importance of S1P in breast cancer. We suggest that S1P is one of the key molecules to overcome the resistance to the drug therapies, such as hormonal therapy, anti-HER2 therapy, or chemotherapy, all of which are crucial aspects of a breast cancer treatment.

S1P Provokes Tumor Lymphangiogenesis via Macrophage-Derived Mediators Such as IL-1β or Lipocalin-2

A pleiotropic signaling lipid, sphingosine-1-phosphate (S1P), has been implicated in various pathophysiological processes supporting tumor growth and metastasis. However, there are only a few descriptive studies suggesting a role of S1P in tumor lymphangiogenesis, which is critical for tumor growth and dissemination. Corroborating own data, the literature suggests that apoptotic tumor cell-derived S1P alters the phenotype of tumor-associated macrophages (TAMs) to gain protumor functions. However, mechanistically, the role of TAM-induced lymphangiogenesis has only been poorly described, mostly linked to the production of lymphangiogenic factors such as vascular endothelial growth factor C (VEGF-C) and VEGF-D, or transdifferentiation into lymphatic endothelial cells. Recent findings highlight a rather underappreciated role of S1P in tumor lymphangiogenesis, referring to the production of interleukin-1β (IL-1β) and lipocalin-2 (LCN2) by a tumor-promoting macrophage phenotype. In this review, we aim to provide to the readers with the current understanding of the molecular mechanism how apoptotic cell-derived S1P triggers TAMs to promote lymphangiogenesis.

The role of sphingosine-1-phosphate in the tumor microenvironment and its clinical implications

Elucidating the interaction between cancer and non-cancer cells, such as blood vessels, immune cells, and other stromal cells, in the tumor microenvironment is imperative in understanding the mechanisms underlying cancer progression and metastasis, which is expected to lead to the development of new therapeutics. Sphingosine-1-phosphate is a bioactive lipid mediator that promotes cell survival, proliferation, migration, angiogenesis/lymphangiogenesis, and immune responsiveness, which are all factors involved in cancer progression. Sphingosine-1-phosphate is generated inside cancer cells by sphingosine kinases and then exported into the tumor microenvironment. Although sphingosine-1-phosphate is anticipated to play an important role in the tumor microenvironment and cancer progression, determining sphingosine-1-phosphate levels in the tumor microenvironment has been difficult due to a lack of established methods. We have recently developed a method to measure sphingosine-1-phosphate levels in the interstitial fluid that bathes cancer cells in the tumor microenvironment, and reported that high levels of sphingosine-1-phosphate exist in the tumor interstitial fluid. Importantly, sphingosine-1-phosphate can be secreted from cancer cells and non-cancer components such as immune cells and vascular/lymphatic endothelial cells in the tumor microenvironment. Furthermore, sphingosine-1-phosphate affects both cancer and non-cancer cells in the tumor microenvironment promoting cancer progression. Here, we review the roles of sphingosine-1-phosphate in the interaction between cancer and non-cancer cells in tumor microenvironment, and discuss future possibilities for targeted therapies against sphingosine-1-phosphate signaling for cancer patients.

Angiopoietin pathway gene expression associated with poor breast cancer survival

PURPOSE

Angiogenesis is one of the hallmarks of cancer and is essential for cancer progression and metastasis. However, clinical trials with vascular endothelial growth factor (VEGF) pathway inhibitors have failed to show overall survival benefit in breast cancer. Targeted therapy against the angiopoietin pathway, a downstream angiogenesis cascade, could be effective in breast cancer. This study investigates the association of angiopoietin pathway gene expression with breast cancer survival using a "big data" approach employing RNA sequencing data from The Cancer Genome Atlas (TCGA).

METHODS

A total of 888 patients with adequate gene expression, disease-free survival (DFS), and overall survival (OS) data were selected for analysis. DFS and OS were calculated for patients with high and low expression of angiopoietin and VEGF pathway genes using TCGA data. Gene-specific thresholds to dichotomize patients into high and low expression were determined and survival plots were generated.

RESULTS

The TCGA cohort was representative of national breast cancer patients with respect to stage, pathology, and survival. High Ang2 gene expression was associated with not only decreased DFS (p = 0.05), but also decreased OS (p < 0.05). High co-expression of Ang2 and its receptor Tie2 was associated with both decreased DFS and OS (p < 0.05). There was strong correlation between angiopoietin and VEGF pathway genes. While high expression of VEGFA alone was not associated with survival, high co-expression with Ang2 was associated with decreased OS.

CONCLUSIONS

This study validates TCGA as a representative database providing genomic data and survival outcomes in breast cancer. Our TCGA data support the angiopoietin pathway as a key mediator in the pathologic angiogenic switch in breast cancer.

Sphingosine-1-phosphate in the lymphatic fluid determined by novel methods

Background

Sphingosine-1-phosphate (S1P) is a pleiotropic bioactive lipid mediator that regulates many physiological and pathological processes. It has been suggested that S1P gradient with high concentrations in the blood and lymphatic fluid and low concentrations in the peripheral tissue plays important roles in immune cell trafficking and potentially cancer progression. However, only a few reports have assessed S1P levels in the lymphatic fluid due to lack of an established easy-to-use method. Here, we report a simple technique for collection of lymphatic fluid to determine S1P.

Materials and methods

Lymphatic fluid was collected directly with a catheter needle (classical method) or was absorbed onto filter paper after incision of cisterna chyli (new method) in murine models. Blood, lymphatic fluid and mesenteric lymph nodes were corrected from wild type and sphingosine kinase 2 (SphK2) knockout mice to determine S1P levels by mass spectrometry.

Results

The volume of lymphatic fluid collected by the new method was at least three times greater than those collected by the classical method. S1P concentrations in lymphatic fluid are lower than in blood and higher than in lymph nodes. Interestingly, S1P levels in lymphatic fluid from SphK2 knockout mice were significantly higher than those in wild type, suggesting an important role of SphK2 and/or SphK1 to regulate S1P levels in lymphatic fluid.

Conclusions

In agreement with the previous theory, our results confirm “S1P gradient” among blood, lymphatic fluid and peripheral lymphatic tissues. Convenient methods for collection and measurement of sphingolipids in lymphatic fluid are expected to provide new insights on functions of sphingolipids.

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.

Breast cancer sphingosine-1-phosphate is associated with phospho-sphingosine kinase 1 and lymphatic metastasis

BACKGROUND

Sphingosine-1-phosphate (S1P), a pleiotropic bioactive lipid mediator, has been implicated as a key regulatory molecule in cancer through its ability to promote cell proliferation, migration, angiogenesis, and lymphangiogenesis. Previous studies suggested that S1P produced by sphingosine kinase 1 (SphK1) in breast cancer plays important roles in progression of disease and metastasis. However, the associations between S1P and clinical parameters in human breast cancer have not been well investigated to date.

MATERIALS AND METHODS

We determined levels of S1P and other sphingolipids in breast cancer tissue by electrospray ionization-tandem mass spectrometry. Associations between S1P levels and clinicopathologic features of the tumors were analyzed. Expression of phospho-SphK1 (pSphK1) in breast cancer tissues was determined by immunohistochemical scoring.

RESULTS

Levels of S1P in breast cancer tissues were significantly higher in patients with high white blood cell count in the blood than those patients without. S1P levels were lower in patients with human epidermal growth factor receptor 2 overexpression and/or amplification than those patients without. Furthermore, cancer tissues with high pSphK1 expression showed significantly higher levels of S1P than cancer tissues without. Finally, patients with lymph node metastasis showed significantly higher levels of S1P in tumor tissues than the patients with negative nodes.

CONCLUSIONS

To our knowledge, this is the first study to demonstrate that high expression of pSphK1 is associated with higher levels of S1P, which in turn is associated with lymphatic metastasis in breast cancer.

Computational Identification of Novel Stage-Specific Biomarkers in Colorectal Cancer Progression

It is well-known that the conversion of normal colon epithelium to adenoma and then to carcinoma stems from acquired molecular changes in the genome. The genetic basis of colorectal cancer has been elucidated to a certain extent, and much remains to be known about the identity of specific cancer genes that are associated with the advancement of colorectal cancer from one stage to the next. Here in this study we attempted to identify novel cancer genes that could underlie the stage-specific progression and metastasis of colorectal cancer. We conducted a stage-based meta-analysis of the voluminous tumor genome-sequencing data and mined using multiple approaches for novel genes driving the progression to stage-II, stage-III and stage-IV colorectal cancer. The consensus of these driver genes seeded the construction of stage-specific networks, which were then analyzed for the centrality of genes, clustering of subnetworks, and enrichment of gene-ontology processes. Our study identified three novel driver genes as hubs for stage-II progression: DYNC1H1, GRIN2A, GRM1. Four novel driver genes were identified as hubs for stage-III progression: IGF1R, CPS1, SPTA1, DSP. Three novel driver genes were identified as hubs for stage-IV progression: GSK3B, GGT1, EIF2B5. We also identified several non-driver genes that appeared to underscore the progression of colorectal cancer. Our study yielded potential diagnostic biomarkers for colorectal cancer as well as novel stage-specific drug targets for rational intervention. Our methodology is extendable to the analysis of other types of cancer to fill the gaps in our knowledge.

High levels of sphingolipids in human breast cancer

BACKGROUND

Sphingolipids, including sphingosine-1-phosphate (S1P) and ceramide, have emerged as key regulatory molecules that control various aspects of cell growth and proliferation in cancer. Although important roles of sphingolipids in breast cancer progression have been reported in experimental models, their roles in human patients have yet to be determined. The aims of this study were to determine the levels of sphingolipids including S1P, ceramides, and other sphingolipids, in breast cancer and normal breast tissue and to compare the difference in levels of each sphingolipid between the two tissues.

MATERIALS AND METHODS

Tumor and noncancerous breast tissue were obtained from 12 patients with breast cancer. Sphingolipids including S1P, ceramides, and their metabolites of sphingosine, sphingomyelin, and monohexosylceramide were measured by liquid chromatography-electrospray ionization-tandem mass spectrometry.

RESULTS

The levels of S1P, ceramides, and other sphingolipids in the tumor were significantly higher than those in normal breast tissue. There was a relatively strong correlation in the levels of S1P between the tumor and those of normal breast tissue from the same person. On the other hand, there was no correlation in the levels of most of the ceramide species between the tumor and those of normal breast tissue from the same person.

CONCLUSIONS

To our knowledge, this is the first study to reveal that levels of sphingolipids in cancer tissue are generally higher than those of normal breast tissue in patients with breast cancer. The correlation of S1P levels in these tissues implicates the role of S1P in interaction between cancer and the tumor microenvironment.

[Effects of oral cancer-associated fibroblasts on the proliferation, migration, invasion and tube formation to human lymphatic endothelial cells]

OBJECTIVE

To investigate the effects of oral cancer-associated fibroblasts (CAFs) on lymphangiogenesis in oral squamous cell carcinoma (OSCC).

METHODS

CAFs and normal fibroblasts (NFs) were obtained from the tissues of patients with OSCC who did not receive radio-chemotherapy before operation. And the CAFs and NFs were isolated by method of tissue block and identified by immunohistochemical staining. The effects of CAFs (group A) and NFs (group B) to human lymphatic endothelial cells (HLEC) were detected by using a 24-multiwell transwell cell culture chamber. DMEM sugar medium was as blank control group. The number of proliferative, migratory, invasive and tubes of HLEC were counted under inverted phase contrast microscope.

RESULTS

The proliferative number of HLEC of group A for 96, 144, 196 h was significantly higher than that of group B and blank control group, group B higher than blank control group (P<0.01). The migratory and invasive number of HLEC of group A for 96 h was significantly higher than that of group B and blank control group, group B higher than blank control group (P<0.01). The number of tube formation of HLEC of group A for 24 h was significantly higher than that of group B and blank control group, group B higher than blank control group (P<0.01).

CONCLUSION

CAFs promote HLEC's proliferation, migration, invasion, tube formation, and these effects are stronger than NFs.

[Effects of oral cancer-associated fibroblasts on the proliferation, migration, invasion and tube formation to human lymphatic endothelial cells]

OBJECTIVE

To investigate the effects of oral cancer-associated fibroblasts (CAFs) on lymphangiogenesis in oral squamous cell carcinoma (OSCC).

METHODS

CAFs and normal fibroblasts (NFs) were obtained from the tissues of patients with OSCC who did not receive radio-chemotherapy before operation. And the CAFs and NFs were isolated by method of tissue block and identified by immunohistochemical staining. The effects of CAFs (group A) and NFs (group B) to human lymphatic endothelial cells (HLEC) were detected by using a 24-multiwell transwell cell culture chamber. DMEM sugar medium was as blank control group. The number of proliferative, migratory, invasive and tubes of HLEC were counted under inverted phase contrast microscope.

RESULTS

The proliferative number of HLEC of group A for 96, 144, 196 h was significantly higher than that of group B and blank control group, group B higher than blank control group (P<0.01). The migratory and invasive number of HLEC of group A for 96 h was significantly higher than that of group B and blank control group, group B higher than blank control group (P<0.01). The number of tube formation of HLEC of group A for 24 h was significantly higher than that of group B and blank control group, group B higher than blank control group (P<0.01).

CONCLUSION

CAFs promote HLEC's proliferation, migration, invasion, tube formation, and these effects are stronger than NFs.

A potential small-molecule synthetic antilymphangiogenic agent norcantharidin inhibits tumor growth and lymphangiogenesis of human colonic adenocarcinomas through blocking VEGF-A,-C,-D/VEGFR-2,-3 "multi-points priming" mechanisms in vitro and in vivo

Background

Tumor lymphangiogenesis plays an important role in promoting growth and metastasis of tumors, but no antilymphangiogenic agent is used clinically. Based on the effect of norcantharidin (NCTD) on lymphangiogenesis of human lymphatic endothelial cells (LECs), we firstly investigated the antilymphangiogenic activity of NCTD as a tumor lymphangiogenic inhibitor for human colonic adenocarcinomas (HCACs).

Methods

In vivo and in vitro experiments to determine the effects of NCTD on tumor growth and lymphangiogenesis of the in-situ colonic xenografts in nude mice, and lymphatic tube formation of the three-dimensional (3-D) of the co-culture system of HCAC HT-29 cells and LECs were done. Proliferation, apoptosis, migration, invasion, Ki-67, Bcl-2 and cell cycle of LECs and the co-culture system in vitro were respectively determined. Streparidin-peroxidase staining, SABC, western blotting and RT-PCR were respectively used to examine the expression of LYVE-1, D2-40, CK20 (including their LMVD), and VEGF-A, VEGF-C, VEGF-D, VEGFR-2 and VEGFR-3 in vitro and in vivo.

Results

NCTD inhibited tumor growth and lymphangiogenesis of the in-situ colonic xenografts in vivo, and these observations were confirmed by facts that lymphatic tube formation, proliferation, apoptosis, migration, invasion, S-phase cell cycle, and Ki-67 and Bcl-2 expression in vitro, and LYVE-1, D2-40, CK20 expression and their LMVD in vitro and in vivo were inhibited and affected. Furthermore, the expression of VEGF-A, VEGF-C, VEGF-D, VEGFR-2 and VEGFR-3 at protein/mRNA levels in the process of lymphatic tube formation in vitro and tumor lymphangiogenesis in vivo was downregulated; NCTD in combination with mF4-31C1 or Sorafenib enhanced these effects.

Conclusions

NCTD inhibits tumor growth and lymphangiogenesis of HCACs through “multi-points priming” mechanisms i.e. affecting related malignant phenotypes, inhibiting Ki-67 and Bcl-2 expression, inducing S-phase cell cycle arrest, and directly or indirectly downregulating VEGF-A,-C,-D/VEGFR-2,-3 signaling pathways. The present finding strongly suggests that NCTD could serve as a potential antilymphangiogenic agent for tumor lymphangiogenesis and is of importance to explore NCTD is used for antitumor metastatic comprehensive therapy for HCACs.

Vascular endothelial growth factor C disrupts the endothelial lymphatic barrier to promote colorectal cancer invasion

BACKGROUND & AIMS

Colorectal cancer (CRC) is highly metastatic. Metastases spread directly into local tissue or invade distant organs via blood and lymphatic vessels, but the role of lymphangiogenesis in CRC progression has not been determined. Lymphangiogenesis is induced via vascular endothelial growth factor C (VEGFC) activation of its receptor, VEGFR3; high levels of VEGFC have been measured in colorectal tumors undergoing lymphangiogenesis and correlated with metastasis. We investigated VEGFC signaling and lymphatic barriers in human tumor tissues and mice with orthotopic colorectal tumors.

METHODS

We performed immunohistochemical, immunoblot, and real-time polymerase chain reaction analyses of colorectal tumor specimens collected from patients; healthy intestinal tissues collected during operations of patients without CRC were used as controls. CT26 CRC cells were injected into the distal posterior rectum of BALB/c-nude mice. Mice were given injections of an antibody against VEGFR3 or an adenovirus encoding human VEGFC before orthotopic tumors and metastases formed. Lymph node, lung, and liver tissues were collected and evaluated by flow cytometry. We measured expression of vascular endothelial cadherin (CDH5) on lymphatic vessels in mice and in human intestinal lymphatic endothelial cells.

RESULTS

Levels of podoplanin (a marker of lymphatic vessels), VEGFC, and VEGFR3 were increased in colorectal tumor tissues, compared with controls. Mice that expressed VEGFC from the adenoviral vector had increased lymphatic vessel density and more metastases in lymph nodes, lungs, and livers, compared with control mice. Anti-VEGFR3 antibody reduced numbers of lymphatic vessels in colons and prevented metastasis. Expression of VEGFC compromised the lymphatic endothelial barrier in mice and endothelial cells, reducing expression of CDH5, increasing permeability, and increasing trans-endothelial migration by CRC cells. Opposite effects were observed in mice and cells when VEGFR3 was blocked.

CONCLUSIONS

VEGFC signaling via VEGFR3 promotes lymphangiogenesis and metastasis by orthotopic colorectal tumors in mice and reduces lymphatic endothelial barrier integrity. Levels of VEGFC and markers of lymphatic vessels are increased in CRC tissues from patients, compared with healthy intestine. Strategies to block VEGFR3 might be developed to prevent CRC metastasis in patients.

Impact of the prolymphangiogenic crosstalk in the tumor microenvironment on lymphatic cancer metastasis

Lymphangiogenesis is a very early step in lymphatic metastasis. It is regulated and promoted not only by the tumor cells themselves, but also by cells of the tumor microenvironment, including cancer associated fibroblasts, mesenchymal stem cells, dendritic cells, or macrophages. Even the extracellular matrix as well as cytokines and growth factors are involved in the process of lymphangiogenesis and metastasis. The cellular and noncellular components influence each other and can be influenced by the tumor cells. The knowledge about mechanisms behind lymphangiogenesis in the tumor microenvironmental crosstalk is growing and offers starting points for new therapeutic approaches.

Sphingosine-1-phosphate transporters as targets for cancer therapy

Sphingosine-1-phosphate (S1P) is a pleiotropic lipid mediator that regulates cell survival, migration, the recruitment of immune cells, angiogenesis, and lymphangiogenesis, all of which are involved in cancer progression. S1P is generated inside cancer cells by sphingosine kinases then exported outside of the cell into the tumor microenvironment where it binds to any of five G protein coupled receptors and proceeds to regulate a variety of functions. We have recently reported on the mechanisms underlying the "inside-out" signaling of S1P, its export through the plasma membrane, and its interaction with cell surface receptors. Membrane lipids, including S1P, do not spontaneously exchange through lipid bilayers since the polar head groups do not readily go through the hydrophobic interior of the plasma membrane. Instead, specific transporter proteins exist on the membrane to exchange these lipids. This review summarizes what is known regarding S1P transport through the cell membrane via ATP-binding cassette transporters and the spinster 2 transporter and discusses the roles for these transporters in cancer and in the tumor microenvironment. Based on our research and the emerging understanding of the role of S1P signaling in cancer and in the tumor microenvironment, S1P transporters and S1P signaling hold promise as new therapeutic targets for cancer drug development.

Emerging Role of Sphingosine-1-phosphate in Inflammation, Cancer, and Lymphangiogenesis

The main function of the lymphatic system is to control and maintain fluid homeostasis, lipid transport, and immune cell trafficking. In recent years, the pathological roles of lymphangiogenesis, the generation of new lymphatic vessels from preexisting ones, in inflammatory diseases and cancer progression are beginning to be elucidated. Sphingosine-1-phosphate (S1P), a bioactive lipid, mediates multiple cellular events, such as cell proliferation, differentiation, and trafficking, and is now known as an important mediator of inflammation and cancer. In this review, we will discuss recent findings showing the emerging role of S1P in lymphangiogenesis, in inflammation, and in cancer.

Natural history of hepatic metastases from colorectal cancer - pathobiological pathways with clinical significance

Colorectal cancer hepatic metastases represent the final stage of a multi-step biological process. This process starts with a series of mutations in colonic epithelial cells, continues with their detachment from the large intestine, dissemination through the blood and/or lymphatic circulation, attachment to the hepatic sinusoids and interactions with the sinusoidal cells, such as sinusoidal endothelial cells, Kupffer cells, stellate cells and pit cells. The metastatic sequence terminates with colorectal cancer cell invasion, adaptation and colonisation of the hepatic parenchyma. All these events, termed the colorectal cancer invasion-metastasis cascade, include multiple molecular pathways, intercellular interactions and expression of a plethora of chemokines and growth factors, and adhesion molecules, such as the selectins, the integrins or the cadherins, as well as enzymes including matrix metalloproteinases. This review aims to present recent advances that provide insights into these cell-biological events and emphasizes those that may be amenable to therapeutic targeting.

Export of sphingosine-1-phosphate and cancer progression

Sphingosine-1-phosphate (S1P) is a bioactive lipid mediator that promotes cell survival, proliferation, migration, angiogenesis, lymphangiogenesis, and immune response; all are critical processes of cancer progression. Although some important roles of intracellular S1P have recently been uncovered, the majority of its biological effects are known to be mediated via activation of five specific G protein-coupled receptors [S1P receptor (S1PR)1-S1PR5] located on the cell surface. Secretion of S1P produced inside cells by sphingosine kinases can then signal through these receptors in autocrine, paracrine, and/or endocrine manners, coined "inside-out" signaling of S1P. Numerous studies suggest that secreted S1P plays important roles in cancer progression; thus, understanding the mechanism by which S1P is exported out of cells, particularly cancer cells, is both interesting and important. Here we will review the current understanding of the transport of S1P out of cancer cells and its potential roles in the tumor microenvironment.

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.

VEGF-C and VEGF-D overexpression is more common in left-sided and well-differentiated colon adenocarcinoma

Tumour vessel network formation, including blood and lymph vessels, is a major step involved in the process of carcinogenesis. The discovery of vascular growth factors has led to a better understanding of tumour biology, thus, creating new possibilities for cancer treatment that targets angiogenesis within tumour-associated stroma, including therapy for colon cancer patients. The present study evaluated the relationships between increased expression of lymphangiogenic factors (VEGF-C and VEGF-D) and vessel density in the tumour-surrounding stroma, patient survival and other standard prognostic factors. The expression of VEGF-C and VEGF-D and vessel density were immunohistochemically assessed in 114 primary tumour specimens from colon adenocarcinoma patients after surgical resection between January 1, 2003 and December 31, 2008. Concomittant overexpression of VEGF-C and VEGF-D was found in 51 (44.7%) colon tumours and low expression was observed in 63 (55.3%) cases. Mean vessel density was 52.87/field. A significant correlation was found between the expression of factors influencing lymph vessel growth and increased vessel density in the tumour-surrounding stroma (p=0.03). A relationship between lymphangiogenic factor overexpression and left-sided tumour location was also found (p=0.00002). Overexpression of these factors was likely to occur in well-differentiated tumours (p=0.003). No association between patient survival and the expression levels of lymphangiogenic factors was observed. The study results indicate that the overexpression of lymphangiogenic factors tends to be associated with tumours of favourable prognosis, i.e. well-differentiated and those localized in the left-side of the colon.

Sphingosine-1-phosphate in chronic intestinal inflammation and cancer

Sphingosine-1-phosphate (S1P), a pleiotropic bioactive lipid mediator, and the kinase that produces it have now emerged as key regulators of numerous cellular processes involved in inflammation and cancer. Here, we review the importance of S1P in colitis and colitis-associated cancer (CAC) and discuss our recent work demonstrating that S1P produced by upregulation of SphK1 during colitis and associated cancer is essential for production of the multifunctional NF-κB-regulated cytokine IL-6, persistent activation of the transcription factor Stat3, and consequent upregulation of the S1P receptor, S1PR1. The effectiveness of the pro-drug FTY720 (known as fingolimod), approved for the treatment of multiple sclerosis, has become the gold standard for S1P-centric drugs, and will be used to illustrate the therapeutic value of modulating SphK1 and S1P receptor functions. We will discuss our recent results showing that FTY720/fingolimod administration interferes with the SphK1/S1P/S1PR1 axis and suppresses the NF-κB/IL-6/Stat3 malicious amplification loop and CAC. These preclinical studies suggest that FTY720/fingolimod may be useful in treating colon cancer in individuals with ulcerative colitis.

Is tail vein injection a relevant breast cancer lung metastasis model?

BACKGROUND

TWO MOST COMMONLY USED ANIMAL MODELS FOR STUDYING BREAST CANCER LUNG METASTASIS ARE: lung metastasis after orthotopic implantation of cells into the mammary gland, and lung implantations produced after tail vein (TV) injection of cells. Tail vein injection can produce lung lesions faster, but little has been studied regarding the differences between these tumors, thus, we examined their morphology and gene expression profiles.

METHODS

Syngeneic murine mammary adenocarcinoma, 4T1-luc2 cells, were implanted either subcutaneously (Sq), orthotopically (OS), or injected via TV in Balb/c mice. Genome-wide microarray analyses of cultured 4T1 cells, Sq tumor, OS tumor, lung metastases after OS (LMet), and lung tumors after TV (TVt) were performed 10 days after implantation.

RESULTS

Bioluminescence analysis demonstrated different morphology of metastases between LMet and TVt, confirmed by histology. Gene expression profile of cells were significantly different from tumors, OS, Sq, TVt or LMet (10,350 probe sets; FDR≤1%; P<0.0001). Sq tumors were significantly different than OS tumors (700 probe sets; FDR≤15%; P<0.01), and both tumor types (Sq and OS) were significantly different than LMet (1,247 probe sets; >1.5-fold-change; P<0.01), with no significant difference between TVt and LMet.

CONCLUSIONS

There were significant differences between the gene profiles of cells in culture and OS versus LMet, but there were no differences between LMet versus TVt. Therefore, the lung tumor generated by TVt can be considered genetically similar to those produced after OS, and thus TVt is a relevant model for breast cancer lung metastasis.

Photoacoustic imaging: a potential tool to detect early indicators of metastasis

The metastasis of cancer is a multistage process involving complex biological interactions and difficult to predict outcomes. Accurate assessment of the extent of metastasis is critical for clinical practice; unfortunately, medical imaging methods capable of identifying the early stages of invasion and metastasis are lacking. Photoacoustic imaging is capable of providing noninvasive, real-time imaging of significant anatomical and physiological changes. indicating the progression of cancer invasion and metastasis. Preclinically, photoacoustic methods have been used to image lymphatic anatomy, including the sentinel lymph nodes, to identify circulating tumor cells within vasculature and to detect micrometastases. Progress has begun toward the development of clinically applicable photoacoustic imaging systems to assist with the determination of cancer stage and likelihood of metastatic invasion.

Prognostic and survival analysis of 837 Chinese colorectal cancer patients

AIM: To develop a prognostic model to predict survival of patients with colorectal cancer (CRC).

METHODS: Survival data of 837 CRC patients undergoing surgery between 1996 and 2006 were collected and analyzed by univariate analysis and Cox proportional hazard regression model to reveal the prognostic factors for CRC. All data were recorded using a standard data form and analyzed using SPSS version 18.0 (SPSS, Chicago, IL, United States). Survival curves were calculated by the Kaplan-Meier method. The log rank test was used to assess differences in survival. Univariate hazard ratios and significant and independent predictors of disease-specific survival and were identified by Cox proportional hazard analysis. The stepwise procedure was set to a threshold of 0.05. Statistical significance was defined as P < 0.05.

RESULTS: The survival rate was 74% at 3 years and 68% at 5 years. The results of univariate analysis suggested age, preoperative obstruction, serum carcinoembryonic antigen level at diagnosis, status of resection, tumor size, histological grade, pathological type, lymphovascular invasion, invasion of adjacent organs, and tumor node metastasis (TNM) staging were positive prognostic factors (P < 0.05). Lymph node ratio (LNR) was also a strong prognostic factor in stage III CRC (P < 0.0001). We divided 341 stage III patients into three groups according to LNR values (LNR1, LNR ≤ 0.33, n = 211; LNR2, LNR 0.34-0.66, n = 76; and LNR3, LNR ≥ 0.67, n = 54). Univariate analysis showed a significant statistical difference in 3-year survival among these groups: LNR1, 73%; LNR2, 55%; and LNR3, 42% (P < 0.0001). The multivariate analysis results showed that histological grade, depth of bowel wall invasion, and number of metastatic lymph nodes were the most important prognostic factors for CRC if we did not consider the interaction of the TNM staging system (P < 0.05). When the TNM staging was taken into account, histological grade lost its statistical significance, while the specific TNM staging system showed a statistically significant difference (P < 0.0001).

CONCLUSION: The overall survival of CRC patients has improved between 1996 and 2006. LNR is a powerful factor for estimating the survival of stage III CRC patients.

The role of sphingosine-1-phosphate in breast cancer tumor-induced lymphangiogenesis

Sphingosine-1-phosphate (S1P) is a potent sphingolipid metabolite that regulates a number of biological processes critical for cancer. S1P produced inside cancer cells is exported and exerts its extracellular functions by binding to its specific receptors in an autocrine, paracrine, and/or endocrine manner, which is known as inside-out signaling. S1P is also known to exert its intracellular functions especially in the inflammatory process, but its relevance to cancer biology remains to be elucidated. Recently, there have been growing interests in the role of S1P in breast cancer progression, including angiogenesis and lymphangiogenesis. Our group demonstrated that activation of sphingosine kinase 1, the enzyme that catalyzes the phosphorylation of sphingosine to S1P, is a key step of this process. In this review, we will cover our current knowledge on the role of S1P signaling pathway in breast cancer progression with an emphasis on its role in tumor-induced lymphangiogenesis.

Spns2, a transporter of phosphorylated sphingoid bases, regulates their blood and lymph levels, and the lymphatic network

Sphingosine-1-phosphate (S1P), a ligand for 5 specific receptors, is a potent lipid mediator that plays important roles in lymphocyte trafficking and immune responses. S1P is produced inside cells and therefore must be secreted to exert its effects through these receptors. Spinster 2 (Spns2) is one of the cell surface transporters thought to secrete S1P. We have shown that Spns2 can export endogenous S1P from cells and also dihydro-S1P, which is active at all cell surface S1P receptors. Moreover, Spns2 mice have decreased levels of both of these phosphorylated sphingoid bases in blood, accompanied by increases in very long chain ceramide species, and have defective lymphocyte trafficking. Surprisingly, levels of S1P and dihydro-S1P were increased in lymph from Spns2 mice as well as in specific tissues, including lymph nodes, and interstitial fluid. Moreover, lymph nodes from Spns2 mice have aberrant lymphatic sinus that appeared collapsed, with reduced numbers of lymphocytes. Our data suggest that Spns2 is an S1P transporter in vivo that plays a role in regulation not only of blood S1P but also lymph node and lymph S1P levels and consequently influences lymphocyte trafficking and lymphatic vessel network organization.

New model of in-situ xenograft lymphangiogenesis by a human colonic adenocarcinoma cell line in nude mice

OBJECTIVE

To explore a new model of in-situ xenograft lymphangiogenesis of human colonic adenocarcinomas in nude mice.

METHOD

On the basis of establishing subcutaneous xenograft lymphangiogenesis model of human colonic adenocarcinoms, in-situ xenografts were established through the in situ growth of the HT-29 human colonic adenocarcinoma cell line in nude mice. The numbers of lymphangiogenic microvessels, the expression of lymphatic endothelial cell markers lymphatic vessel endothelial hyaloronic acid receptor-1 (LYVE-1), D2-40 and the lymphatic endothelial growth factors vascular endothelial growth factor-C (VEGF-C), -D (VEGF-D) and receptor-3 (VEGFR-3) were compared by immunohistochemical staining, Western bolt and quantitative RT-PCR in xenograft in-situ models.

RESULTS

Some microlymphatics with thin walls, large and irregular or collapsed cavities and increased LMVD, with strong positive of LYVE-1, D2-40 in immunohistochemistry, were observed, identical with the morphological characteristics of lymphatic vessels and capillaries. Expression of LYVE-1 and D2-40 proteins and mRNAs were significantly higher in xenografts in-situ than in the negative control group (both P<0.01). Moreover, the expression of VEGF-C, VEGF-D and VEGFR-3 proteins and mRNAs were significantly higher in xenografts in-situ (both P<0.01), in conformity with the signal regulation of the VEGF-C,-D/VEGFR-3 axis of tumor lymphangiogenesis.

CONCLUSIONS

In-situ xenografts of a human colonic adenocarcinoma cell line demonstrate tumor lymphangiogenesis. This novel in-situ animal model should be useful for further studying mechanisms of lymph node metastasis, drug intervention and anti-metastasis therapy in colorectal cancer.

Recombinant human endostatin endostar suppresses angiogenesis and lymphangiogenesis of malignant pleural effusion in mice

Background

Malignant pleural effusion (MPE) is a common complication of lung cancer. One widely used treatment for MPE is Endostar, a recombined humanized endostatin based treatment. However, the mechanism of this treatment is still unclear. The aim of this study was to investigate the effects of Endostar in mice with MPE.

Methods and Materials

Lewis lung carcinoma (LLC) cell line expressing enhanced green fluorescent protein (EGFP) was injected into pleural cavity to establish MPE mice model. Mice were randomly divided into four groups. High dose of Endostar (30 mg/kg), low dose of Endostar (8 mg/kg), normal saline, or Bevacizumab (5 mg/kg) was respectively injected into pleural cavity three times with 3-day interval in each group. Transverse computed tomography (CT) was performed to observe pleural fluid formation 14 days after LLC cells injection. Mice were anesthetized and sacrificed 3 days after final administration. The volume of pleural effusion n was measured using 1 ml syringe. Micro blood vessel density (MVD), Lymphatic micro vessel density (LMVD), the expression level of vascular endothelial growth factor A (VEGF-A) and VEGF-C were observed by immunohistochemistry (IHC) staining.

Results

The volume of pleural effusion as well as the number of pleural tumor foci, MVD and the expression of VEGF-A were significantly reduced in high dose of Endostar treat group. More importantly, LMVD and the expression of VEGF-C were markedly lower in treat group than those in the other three control groups.

Conclusion

Our work demonstrated that Endostar played an efficient anti-cancer role in MPE through its suppressive effect on angiogenesis and lymphangiogenesis, which provided a certain theoretical basis for the effectiveness of Endostar on the MPE treatment.