Lymphangiogenesis and hemangiogenesis: potential targets for therapy

Clinical Relevancy of Circulating Tumor Cells in Breast Cancer: Epithelial or Mesenchymal Characteristics, Single Cells or Clusters?

Metastatic breast cancer (MBC) is typically an incurable disease with high mortality rates; thus, early identification of metastatic features and disease recurrence through precise biomarkers is crucial. Circulating tumor cells (CTCs) consisting of heterogeneous subpopulations with different morphology and genetic, epigenetic, and gene expression profiles represent promising candidate biomarkers for metastatic potential. The experimentally verified role of epithelial-to-mesenchymal transition in cancer dissemination has not been clearly described in BC patients, but the stemness features of CTCs strongly contributes to metastatic potency. Single CTCs have been shown to be protected in the bloodstream against recognition by the immune system through impaired interactions with T lymphocytes and NK cells, while associations of heterotypic CTC clusters with platelets, leucocytes, neutrophils, tumor-associated macrophages, and fibroblasts improve their tumorigenic behavior. In addition to single CTC and CTC cluster characteristics, we reviewed CTC evaluation methods and clinical studies in early and metastatic BCs. The variable CTC tests were developed based on specific principles and strategies. However, CTC count and the presence of CTC clusters were shown to be most clinically relevant in existing clinical trials. Despite the known progress in CTC research and sampling of BC patients, implementation of CTCs and CTC clusters in routine diagnostic and treatment strategies still requires improvement in detection sensitivity and precise molecular characterizations, focused predominantly on the role of CTC clusters for their higher metastatic potency.

miR-205-5p Downregulation and ZEB1 Upregulation Characterize the Disseminated Tumor Cells in Patients with Invasive Ductal Breast Cancer

Background: Dissemination of breast cancer (BC) cells through the hematogenous or lymphogenous vessels leads to metastatic disease in one-third of BC patients. Therefore, we investigated the new prognostic features for invasion and metastasis. Methods: We evaluated the expression of miRNAs and epithelial-to-mesenchymal transition (EMT) genes in relation to CDH1/E-cadherin changes in samples from 31 patients with invasive ductal BC including tumor centrum (TU-C), tumor invasive front (TU-IF), lymph node metastasis (LNM), and CD45-depleted blood (CD45-DB). Expression of miRNA and mRNA was quantified by RT-PCR arrays and associations with clinico-pathological characteristics were statistically evaluated by univariate and multivariate analysis. Results: We did not verify CDH1 regulating associations previously described in cell lines. However, we did detect extremely high ZEB1 expression in LNMs from patients with distant metastasis, but without regulation by miR-205-5p. Considering the ZEB1 functions, this overexpression indicates enhancement of metastatic potential of lymphogenously disseminated BC cells. In CD45-DB samples, downregulated miR-205-5p was found in those expressing epithelial and/or mesenchymal markers (CTC+) that could contribute to insusceptibility and survival of hematogenously disseminated BC cells mediated by increased expression of several targets including ZEB1. Conclusions: miR-205-5p and potentially ZEB1 gene are promising candidates for markers of metastatic potential in ductal BC.

Comparison of Vascular Invasion With Lymph Node Metastasis as a Prognostic Factor in Stage I-III Colon Cancer: An Observational Cohort Study

Purpose: This study aimed to evaluate the prognostic impact of vascular invasion (VI) in comparison with that of lymph node metastasis (LNM) in non-metastatic colon cancer.

Methods: Patients who underwent curative surgery for stage I-III colon cancer were divided into four groups depending on the status of VI and LNM (Group I: VI-/LNM-; Group II: VI+/LNM-; Group III: VI-/LNM+; Group IV: VI+/LNM+). Group III was subdivided according to the nodal (N) stage (Group IIIA: VI-/N1; Group IIIB: VI-/N2). Oncological outcomes were compared between Groups II and III.

Results: In total, 793 non-metastatic colon cancer patients were included. Group II [hazard ratio (HR) 2.34, 1.01–5.41] and Group III (HR 1.91, 1.26–2.89) were independently associated with poor disease-free survival (DFS). The 5-year DFS rates were comparable in Groups II (71.6%) and III (72.5%) (P = 0.637). When Group III was subdivided into Groups IIIA and IIIB, DFS deteriorated in the following order: Groups IIIA, II, and IIIB. The 5-year DFS rates were 79.7, 71.6, and 61.4% in Groups IIIA, II, and IIIB, respectively. Group II had a tendency toward early recurrence. The 1- and 2-year DFS rates were 76.3 and 71.6% in Group II and 88.3 and 79.8% in Group III, respectively (P = 0.067 and 0.247). All recurrences in Group II were distant metastases.

Conclusion: VI is a prognostic factor as significant as LNM and may be a stronger prognostic factor than N1 stage in non-metastatic colon cancer. Furthermore, a potential association was observed between VI and recurrence patterns, such as early recurrence and distant metastasis.

Galectins as modulators of receptor tyrosine kinases signaling in health and disease

Receptor tyrosine kinases (RTKs) constitute a large group of cell surface proteins that mediate communication of cells with extracellular environment. RTKs recognize external signals and transfer information to the cell interior, modulating key cellular activities, like metabolism, proliferation, motility, or death. To ensure balanced stream of signals the activity of RTKs is tightly regulated by numerous mechanisms, including receptor expression and degradation, ligand specificity and availability, engagement of co-receptors, cellular trafficking of the receptors or their post-translational modifications. One of the most widespread post-translational modifications of RTKs is glycosylation of their extracellular domains. The sugar chains attached to RTKs form a new layer of information, so called glyco-code that is read by galectins, carbohydrate binding proteins. Galectins are family of fifteen lectins implicated in immune response, inflammation, cell division, motility and death. The versatility of cellular activities attributed to galectins is a result of their high abundance and diversity of their cellular targets. A various sugar specificity of galectins and the differential ability of galectin family members to form oligomers affect the spatial distribution and the function of their cellular targets. Importantly, galectins and RTKs are tightly linked to the development, progression and metastasis of various cancers. A growing number of studies points on the close cooperation between RTKs and galectins in eliciting specific cellular responses. This review focuses on the identified complexes between galectins and RTK members and discusses their relevance for the cell physiology both in healthy tissues and in cancer.

Lymphatic and Mixed Malformations

Lymphatic and mixed malformations are rare and variable in presentation. They arise due to errors in vascular and lymphatic formation during early embryonic development. This leads to persistent infiltration of lymph fluid into soft tissues and causes a locally invasive mass with pathologic sequelae. Departing from historically descriptive terminology, such as "cystic hygroma," lymphatic malformations are now categorized as macrocystic, microcystic, or mixed lesions, based on size. Advances in imaging modalities, such as ultrasonography and magnetic resonance imaging, have made accurate characterization of these lesions possible and ultimately allow for early diagnosis and implementation of appropriate treatment based on the morphology of the lymphatic malformation. Management of lymphatic malformations can be quite challenging, and a multidisciplinary approach is most effective for optimum aesthetic and functional outcomes. New discoveries in the molecular biology of lymphatic malformations have provided treatment targets and established a role for pharmacotherapy. Sclerotherapy, laser, and radiofrequency ablation have all proven to be effective as minimally invasive treatment options for lymphatic malformations. Surgical intervention has a role in the treatment of focal lesions recalcitrant to these less invasive techniques. Operative planning is dictated by clinical goals, size, anatomic location, characteristics, and extent of infiltration.

A novel hydrazide compound exerts anti-metastatic effect against breast cancer

Background

There are currently a number of barriers hindering the successful treatment of breast cancer, including the metastatic spread of cancer cells. In looking for new anticancer agents, we reported two novel hydrazide derivatives with anti-cancer activity in human breast cancer cells. The current study aims to explore the therapeutic potential of the most effective one, N'-((5-nitrothiophen-2-yl)methylene)-2-(phenylthio)benzohydrazide (compound B), on metastatic breast cancer, which is resistant to available chemotherapeutics.

Methods

4T1 mammary carcinoma cells were inoculated into the fat pad mammary of 5–7-week-old female BALB/c mice and then the effective compound was intraperitoneally administered for 4 weeks. Proliferation index and angiogenesis in tumor and lung tissues were examined with immunohistochemistry. In vitro assessments were also carried out to evaluate the effect of the compound on invasion of MDA-MB-231 cells.

Results

Our results demonstrated that this effective derivative significantly inhibited invasion of MDA-MB-231 cells in vitro as shown by Matrigel assay and quantitative real-time method for MMP-9 expression after 48 h of treatment. Daily administration of the compound suppressed the growth of primary tumor and its metastasis to lung, which was confirmed by H&E experiment at a dose of 1 mg/kg in a well-known metastatic model of 4T1 breast cancer in syngeneic BALB/c mice. These outcomes were supported by the immunohistochemical examinations of the tumor and lung tissues of mice. Tumors and lungs in mice treated with the effective compound showed a reduced proliferation index and a smaller microvessel density compared to the control.

Conclusion

This study highlights an anti-metastatic role for a novel hydrazide derivative in both in vitro and in vivo models of breast cancer.

Electronic supplementary material

The online version of this article (10.1186/s40659-019-0247-2) contains supplementary material, which is available to authorized users.

Decreased methylation in the SNAI2 and ADAM23 genes associated with de-differentiation and haematogenous dissemination in breast cancers

BACKGROUND

In breast cancer (BC), deregulation of DNA methylation leads to aberrant expressions and functions of key regulatory genes. In our study, we investigated the relationship between the methylation profiles of genes associated with cancer invasivity and clinico-pathological parameters. In detail, we studied differences in the methylation levels between BC patients with haematogenous and lymphogenous cancer dissemination.

METHODS

We analysed samples of primary tumours (PTs), lymph node metastases (LNMs) and peripheral blood cells (PBCs) from 59 patients with sporadic disseminated BC. Evaluation of the DNA methylation levels of six genes related to invasivity, ADAM23, uPA, CXCL12, TWIST1, SNAI1 and SNAI2, was performed by pyrosequencing.

RESULTS

Among the cancer-specific methylated genes, we found lower methylation levels of the SNAI2 gene in histologic grade 3 tumours (OR = 0.61; 95% CI, 0.39-0.97; P = 0.038) than in fully or moderately differentiated cancers. We also evaluated the methylation profiles in patients with different cancer cell dissemination statuses (positivity for circulating tumour cells (CTCs) and/or LNMs). We detected the significant association between reduced DNA methylation of ADAM23 in PTs and presence of CTCs in the peripheral blood of patients (OR = 0.45; 95% CI, 0.23-0.90; P = 0.023).

CONCLUSION

The relationships between the decreased methylation levels of the SNAI2 and ADAM23 genes and cancer de-differentiation and haematogenous dissemination, respectively, indicate novel functions of those genes in the invasive processes. After experimental validation of the association between the lower values of SNAI2 and ADAM23 methylation and clinical features of aggressive BCs, these methylation profiles could improve the management of metastatic disease.

Prognostic value of radiologically enlarged lymph nodes in patients with metastatic colorectal cancer: Subgroup findings of the randomized, open-label FIRE-3/AIO KRK0306 trial

PURPOSE

To determine the prognostic impact of radiologically enlarged lymph nodes ≥ 10 mm on the survival of patients with metastatic colorectal cancer.

MATERIALS AND METHODS

The prospective, randomized, open-label FIRE-3/AIO KRK0306 trial evaluated the first-line therapy of patients with KRAS exon 2 wild-type metastatic colorectal cancer with fluorouracil, folinic acid and irinotecan plus either cetuximab or bevacizumab. In the RAS wild-type population (n = 400), adequately evaluable baseline computed tomographies (n = 339) were reviewed for enlarged regional and distant lymph nodes. Their prognostic relevance was retrospectively analyzed in uni- and multivariable Cox proportional hazard regressions.

RESULTS

Median overall survival was 21.7 months in patients with enlarged lymph nodes and 33.2 months in patients without (hazard rate ratio [HR] = 1.61, 95% confidence interval [CI], 1.23-2.09; P < 0.001). This was confirmed in multivariable analysis (HR = 1.37, 95% CI, 1.02-1.83; P = 0.036). Progression-free survival of patients with enlarged lymph nodes showed a consistent but insignificant trend (9.9 vs. 11.1 months; HR = 1.23, 95% CI, 0.98-1.54; P = 0.072). Enlarged lymph nodes were also associated with BRAF-mutations (P = 0.004).

CONCLUSION

The presence of radiologically enlarged lymph nodes in baseline staging has a negative prognostic value beyond established and potential prognostic parameters.

Novel application assigned to toluquinol: inhibition of lymphangiogenesis by interfering with VEGF-C/VEGFR-3 signalling pathway

BACKGROUND AND PURPOSE

Lymphangiogenesis is an important biological process associated with the pathogenesis of several diseases, including metastatic dissemination, graft rejection, lymphoedema and other inflammatory disorders. The development of new drugs that block lymphangiogenesis has become a promising therapeutic strategy. In this study, we investigated the ability of toluquinol, a 2-methyl-hydroquinone isolated from the culture broth of the marine fungus Penicillium sp. HL-85-ALS5-R004, to inhibit lymphangiogenesis in vitro, ex vivo and in vivo.

EXPERIMENTAL APPROACH

We used human lymphatic endothelial cells (LECs) to analyse the effect of toluquinol in 2D and 3D in vitro cultures and in the ex vivo mouse lymphatic ring assay. For in vivo approaches, the transgenic Fli1:eGFPy1 zebrafish, mouse ear sponges and cornea models were used. Western blotting and apoptosis analyses were carried out to search for drug targets.

KEY RESULTS

Toluquinol inhibited LEC proliferation, migration, tubulogenesis and sprouting of new lymphatic vessels. Furthermore, toluquinol induced apoptosis of LECs after 14 h of treatment in vitro, blocked the development of the thoracic duct in zebrafish and reduced the VEGF-C-induced lymphatic vessel formation and corneal neovascularization in mice. Mechanistically, we demonstrated that this drug attenuates VEGF-C-induced VEGFR-3 phosphorylation in a dose-dependent manner and suppresses the phosphorylation of Akt and ERK1/2.

CONCLUSIONS AND IMPLICATIONS

Based on these findings, we propose toluquinol as a new candidate with pharmacological potential for the treatment of lymphangiogenesis-related pathologies. Notably, its ability to suppress corneal neovascularization paves the way for applications in vascular ocular pathologies.

Pathological lymphangiogenesis is modulated by galectin-8-dependent crosstalk between podoplanin and integrin-associated VEGFR-3

Lymphangiogenesis plays a pivotal role in diverse pathological conditions. Here, we demonstrate that a carbohydrate-binding protein, galectin-8, promotes pathological lymphangiogenesis. Galectin-8 is markedly upregulated in inflamed human and mouse corneas, and galectin-8 inhibitors reduce inflammatory lymphangiogenesis. In the mouse model of corneal allogeneic transplantation, galectin-8-induced lymphangiogenesis is associated with an increased rate of corneal graft rejection. Further, in the murine model of herpes simplex virus keratitis, corneal pathology and lymphangiogenesis are ameliorated in Lgals8(-/-) mice. Mechanistically, VEGF-C-induced lymphangiogenesis is significantly reduced in the Lgals8(-/-) and Pdpn(-/-) mice; likewise, galectin-8-induced lymphangiogenesis is reduced in Pdpn(-/-) mice. Interestingly, knockdown of VEGFR-3 does not affect galectin-8-mediated lymphatic endothelial cell (LEC) sprouting. Instead, inhibiting integrins α1β1 and α5β1 curtails both galectin-8- and VEGF-C-mediated LEC sprouting. Together, this study uncovers a unique molecular mechanism of lymphangiogenesis in which galectin-8-dependent crosstalk among VEGF-C, podoplanin and integrin pathways plays a key role.

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.

Intrahepatic lymphatic invasion but not vascular invasion is a major prognostic factor after resection of colorectal cancer liver metastases

BACKGROUND

Despite advances in diagnosis and surgical strategies, up to 70% of patients will develop recurrence of the disease after resection of colorectal cancer liver metastases (CRCLM). The purpose of our study was to determine the frequency of four different mechanisms of intrahepatic dissemination, and to evaluate the impact of each mechanism on patient outcomes.

METHODS

The medical records of 118 patients who underwent a first resection of CRCLM during the period between 2000 and 2010 were reviewed. Clinicopathologic variables and outcome parameters were examined. Resected specimens were submitted to routine histological evaluation, and immunohistochemical staining with D2-40 (lymphatic vessels), CD34 (blood vessels), CK-7 (biliary epithelium), and CK-20 (CRC cells).

RESULTS

The mean follow-up after resection was 38 months. Tumor recurrence was observed in 76 patients, with a median interval of 13 months after resection. Overall survival and disease-free survival (DFS) rates after hepatectomy were 62 and 56%, and 26 and 24% at 3 and 5 years, respectively. Intrahepatic microscopic invasion included portal venous in 49 patients, sinusoidal in 43 patients, biliary in 20 patients, and lymphatic in 33 patients. Intra-hepatic lymphatic invasion was the only mechanism of dissemination independently associated with the risk of hepatic recurrence (odds ratio 2.75) and shorter DFS (p = 0.006).

CONCLUSION

Intrahepatic lymphatic invasion is a significant prognostic factor. Other mechanisms of invasion, although frequently observed, are not related to recurrence or survival, suggesting that the lymphatic system is the main route for dissemination of CRCLM. Furthermore, immunohistochemical detection of intrahepatic lymphatic invasion might be of value in clinical practice.

VEGF-C induces lymphangiogenesis and angiogenesis in the rat mesentery culture model

OBJECTIVE

Lymphatic and blood microvascular systems are critical for tissue function. Insights into the coordination of both systems can be gained by investigating the relationships between lymphangiogenesis and angiogenesis. Recently, our laboratory established the rat mesentery culture model as a novel tool to investigate multicellular interactions during angiogenesis in an intact microvascular network scenario. The objective of this study was to determine whether the rat mesentery culture model can be used to study lymphangiogenesis.

METHODS

Mesenteric tissue windows were harvested from adult male Wistar rats and cultured for three or five days in either serum-free MEM or MEM supplemented with VEGF-C. Tissues were immunolabeled for PECAM and LYVE-1 to identify blood and lymphatic endothelial cells, respectively. Tissues selected randomly from those containing vascular networks were quantified for angiogenesis and lymphangiogenesis.

RESULTS

VEGF-C treatment resulted in an increase in the density of blood vessel sprouting compared to controls by day 3. By day 5, lymphatic sprouting was increased compared to controls.

CONCLUSIONS

These results are consistent with in vivo findings that lymphangiogenesis lags angiogenesis after chronic stimulation and establish a tool for investigating the interrelationships between lymphangiogenesis and angiogenesis in a multisystem microvascular environment.

Impact of proteolytic enzymes in colorectal cancer development and progression

Tumor invasion and metastasis is a highly complicated, multi-step phenomenon. In the complex event of tumor progression, tumor cells interact with basement membrane and extracellular matrix components. Proteolytic enzymes (proteinases) are involved in the degradation of extracellular matrix, but also in cancer invasion and metastasis. The four categories of proteinases (cysteine-, serine-, aspartic-, and metalloproteinases) are named and classified according to the essential catalytic component in their active site. We and others have shown that proteolytic enzymes play a major role not only in colorectal cancer (CRC) invasion and metastasis, but also in malignant transformation of precancerous lesions into cancer. Tissue and serum-plasma antigen concentrations of proteinases might be of great value in identifying patients with poor prognosis in CRC. Our results, in concordance with others indicate the potential tumor marker impact of proteinases for the early diagnosis of CRC. In addition, proteinases may also serve as potential target molecules for therapeutic agents.

Lymphatic drainage of the liver and its implications in the management of colorectal cancer liver metastases

The liver is the most common site of distant metastases in patients with colorectal cancer. Surgery represents the mainstream for curative treatment of colorectal cancer liver metastases (CRCLM) with long-term survival up to 58 and 36 % at 5 and 10 years, respectively. Despite advances on diagnosis, staging and surgical strategies, 60-70 % of patients will develop recurrence of the disease even after R0 resection of CRCLM. Tumor staging, prognosis, and therapeutic approaches for cancer are most often based on the extent of involvement of regional lymph nodes (LNs) and, to a lesser extent, on the invasion of regional lymphatic vessels draining the primary tumor. For CRCLM, the presence of intra hepatic lymphatic and blood vascular dissemination has been associated with an increased risk of intra hepatic recurrence, poorer disease-free and overall survival after liver resection. Also, several studies have reviewed the role of surgery in the patient with concomitant CRCLM and liver pedicle LN metastasis. Although pedicle LN involvement is related to worst survival rates, it does not differentiate patients that will relapse from those that will not. This review aims to briefly describe the anatomy of the liver's lymphatic drainage, the incidence of intrahepatic lymphatic invasion and hilar lymph node involvement, as well as their clinical impact in CRCLM. A better understanding of the role of liver lymphatic metastasis might, in the near future, impact the strategy of systemic therapies after liver resection as for primary colorectal tumors.

Inhibition of lymphoma vascularization and dissemination by estrogen receptor β agonists

Most lymphomas show an increased incidence and poorer prognosis in males vs females, suggesting endocrine regulation. We have previously shown that tumor growth in vivo of a murine T-cell-derived lymphoma is repressed following activation of estrogen receptor β (ERβ, ESR2). By using ERβ-deficient mice, we now demonstrate that this inhibition is mediated via a direct effect on the tumor cells and not on the microenvironment. Furthermore, we show that the growth-suppressing effects of ERβ agonist are also valid for human B-cell lymphomas as demonstrated in tumors derived from Granta-519 mantle cell lymphoma (MCL) and Raji Burkitt lymphoma (BL) cells. In Granta-519 MCL tumors, activation of ERβ reduced expression of BAFF and GRB7, 2 important molecules involved in B-cell proliferation and survival. Importantly, activation of ERβ inhibited angiogenesis and lymphangiogenesis, possibly mediated by impaired vascular endothelial growth factor C expression. Furthermore, using disseminating Raji BL cells, we show that ERβ activation reduces dissemination of grafted Raji BL tumors. We also show by immunohistochemistry that ERβ is expressed in primary MCL tissue. These results suggest that targeting ERβ with agonists may be valuable in the treatment of some lymphomas, affecting several aspects of the malignant process, including proliferation, vascularization, and dissemination.

The behavior of matrix metalloproteinases and their inhibitors in colorectal cancer

Matrix metalloproteinases (MMPs) play an important role in the degradation of extracellular matrix components crucial for tumor growth, invasion and metastasis. MMPs are controlled by natural inhibitors called tissue inhibitors of metalloproteinases (TIMPs). We and others have demonstrated that MMPs and TIMPs are especially important in the process of tumor invasion, progression and the metastasis of colorectal cancer (CRC). It has been proposed that MMPs and TIMPs might play a part not only in tumor invasion and initiation of metastasis but also in carcinogenesis from colorectal adenomas. Several recent studies demonstrated that high preoperative serum or plasma MMP-2, MMP-9 and TIMP-1 antigen levels are strong predictive factors for poor prognosis in patients with CRC and their determination might be useful for identification of patients with higher risk for cancer recurrence. MMP-9 and TIMP-1 have significant potential tumor marker impact in CRC. Their diagnostic sensitivity is consistently higher than those of conventional biomarkers. The pharmacological targeting of CRC by the development of a new generation of selective inhibitors of MMPs, that is highly specific for certain MMPs, is a promising and challenging area for the future.

Lymphatics, lymph nodes and the immune system: barriers and gateways for cancer spread

Metastasis to the regional lymph node is the most important prognostic indicator for the outcomes of patients with sold cancer. In general, it is well recognized that cancer development is genetically determined with progression from the microenvironment of the primary tumor site, oftentimes via the SLN gateway, to the distant sites. In about 20 % of the time, the cancer cells may spread directly through the blood vascular system to the distant sites. Thus, in general, cancer progression is consistent with Hellman's spectrum theory in that development of nodal and systemic metastasis from a localized cancer growth is a progressive process. Cancer proliferation within the tumor microenvironment may give rise to increased tumor heterogeneity, which is further complicated by its continuous change through its evolution within the host in a Darwinian sense. It is crucial to understand the molecular process of lymphangiogenesis and hemangiogenesis in the tumor microenvironment with respect to the initial steps of cancer cells entering into the lymphatic and vascular systems so that rational therapy can be developed to curb the process of specific routes of metastasis. This chapter elucidates the role of lymphatics, nodal metastasis and antitumor immunity. We present novel immune targets in nodal metastases, the importance of the lymph node as a pre-metastatic niche, and immune-related proteins as biomarkers of metastasis.

Overlapping biomarkers, pathways, processes and syndromes in lymphatic development, growth and neoplasia

Recent discoveries in molecular lymphology, developmental biology, and tumor biology in the context of long-standing concepts and observations on development, growth, and neoplasia implicate overlapping pathways, processes, and clinical manifestations in developmental disorders and cancer metastasis. Highlighted in this review are some of what is known (and speculated) about the genes, proteins, and signaling pathways and processes involved in lymphatic/blood vascular development in comparison to those involved in cancer progression and spread. Clues and conundra from clinical disorders that mix these processes and mute them, including embryonic rests, multicentric nests of displaced cells, uncontrolled/invasive "benign" proliferation and lymphogenous/hematogenous "spread", represent a fine line between normal development and growth, dysplasia, benign and malignant neoplasia, and "metastasis". Improved understanding of these normal and pathologic processes and their underlying pathomechanisms, e.g., stem cell origin and bidirectional epithelial-mesenchymal transition, could lead to more successful approaches in classification, treatment, and even prevention of cancer and a whole host of other diseases.

The role of inflammation and proteinases in tumor progression

Chronic inflammation is an important risk factor for the development of cancers. The link between chronic inflammation and the risk of developing cancer is now well established. At least 20% of all cancers arise in association with infection and chronic inflammation. Inflammation and cancer are linked both along intrinsic (driven by genetic events causing malignancy) and extrinsic (driven by inflammatory conditions predisposing to tumor) pathways. Proteinases are key contributors to the breakdown and reconstitution of extracellular matrix components in physiological processes and pathological conditions, including destructive diseases and tumor progression. Matrix metalloproteinases are especially essential in the complex process of coregulation between cellular components of the tumor environment, and they are considered as potential diagnostic and prognostic biomarkers in many types and stages of cancer. Although the link between chronic inflammation, proteinases and risk of developing cancer is now well established, several open questions remain. The most exciting challenge is to find the best approach to target cancer-associated inflammation in patients with cancer. With respect to matrix metalloproteinases, the development of a new generation of selective inhibitors is a promising area of research.

Endothelin-1 cooperates with hypoxia to induce vascular-like structures through vascular endothelial growth factor-C, -D and -A in lymphatic endothelial cells

AIMS

Lymphangiogenesis refers to the formation of new lymphatic vessels and is thought to constitute conduits for the tumor cells to metastasize. We previously demonstrated that endothelin (ET)-1 through its binding with ETB receptor (ET(B)R) expressed on lymphatic endothelial cells (LEC), induced cell growth and invasiveness. Since vascular endothelial growth factor (VEGF)-A/-C/-D, and hypoxia play key role in lymphatic differentiation, in this study we investigated the involvement of these growth factors and hypoxia in ET-1-induced lymphangiogenesis.

MAIN METHODS

Real time PCR and ELISA were used to quantify VEGF-A/-C/-D. LEC morphological differentiation was analyzed by tube formation assay on Matrigel.

KEY FINDINGS

Hypoxia, as well as ET-1, induced an increase in VEGF-A/-C and -D expression that was reduced in the presence of a selective ET(B)R antagonist, BQ788, and enhanced when ET-1 was administered under hypoxic conditions. We analyzed the role of hypoxia on LEC morphological differentiation, and found that hypoxia increased the formation of vascular-like structures on Matrigel and that in combination with ET-1 this effect was markedly enhanced. The use of specific antibodies neutralizing VEGF-A, or recombinant VEGFR-3/(Flt-4)/Fc that block VEGF-C/-D, inhibited the effect of ET-1 as well that of hypoxia.

SIGNIFICANCE

These results demonstrated that ET-1 and hypoxia act, at list in part, through VEGF to induce lymphangiogenic events and that these two stimuli may cooperate to induce VEGF-A/-C/-D expression and lymphatic differentiation. These data further support the role of ET-1 as potent lymphangiogenic factor that relies on the interplay with hypoxic microenvironment and with VEGF family members.

Impact of nodal status and tumor burden in sentinel lymph nodes on the clinical outcomes of cancer patients

The validation of sentinel lymph node (SLN) concept in melanoma and breast cancer has established a new paradigm in cancer metastasis that, in general, cancer cells spread in a orderly fashion from the primary site to the SLNs in the regional nodal basin and then to the distant sites. In this review article, we examine the development of SLN concept in penile carcinoma, melanoma and breast carcinoma and its application to other solid cancers with emphasis of the relationship between micrometastasis in SLNs and clinical outcomes.

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.