Maureen Van de Velde

Consensus guidelines for the use and interpretation of angiogenesis assays

AbstractThe formation of new blood vessels, or angiogenesis, is a complex process that plays important roles in growth and development, tissue and organ regeneration, as well as numerous pathological conditions. Angiogenesis undergoes multiple discrete steps that can be individually evaluated and quantified by a large number of bioassays. These independent assessments hold advantages but also have limitations. This article describes in vivo, ex vivo, and in vitro bioassays that are available for the evaluation of angiogenesis and highlights critical aspects that are relevant for their execution and proper interpretation. As such, this collaborative work is the first edition of consensus guidelines on angiogenesis bioassays to serve for current and future reference.

Assessment of oxidative stress in tumors and histologically normal mucosa from patients with head and neck squamous cell carcinoma: a preliminary study.

Over 90% of head and neck cancers are squamous cell carcinomas (HNSCC) and the overall 5-year survival rate is up to 50%. The redox status of these cancers is an important factor in carcinogenesis and plays a role in radioresistance and therefore locoregional recurrences. However, knowledge of the redox status is rather limited. Glutathione is the major reactive oxygen species scavenger in normal cells. We compared the levels of tissue redox potential in HNSCC tumor tissue and compared them with those of the adjacent, histologically cancer-free, mucosa. A total of 36 patients with HNSCC were included in the study. The redox status of tumor and normal adjacent tissue was measured by the oxidized/reduced glutathione (GSSG/GSH) ratio in capillary electrophoresis. The GSSG/GSH ratio in the tumor tissue was lower compared with adjacent normal tissue in 38% of the patients. Pretherapy HNSCC tumor tissue has variable GSH levels compared with adjacent cancer-free mucosa. This difference was not related to clinical and pathological parameters. Further studies are required to determine whether the GSSG/GSH ratio plays a role in carcinogenesis and could predict radioresistance.

Targeting VEGFR-3/-2 signaling pathways with AD0157: a potential strategy against tumor-associated lymphangiogenesis and lymphatic metastases

BackgroundLymphatic metastasis is one of the leading causes of death in patients with different types of cancer and is the main prognostic factor for the disease survival. The formation of new lymphatic vessels (lymphangiogenesis) in primary tumors facilitates tumor cell dissemination to regional lymph nodes and correlates with distant metastases. Lymphangiogenesis has thus emerged as a suitable therapeutic target to block metastases, but no anti-lymphangiogenic compounds have been approved for clinical use to date. Therefore, new or improved therapies blocking lymphatic metastases are urgently required.MethodsWe established murine breast tumors to assess the effect of AD0157 on tumor growth, lymphangiogenesis, and lymphatic dissemination. Then, a battery of in vivo (mouse corneal neovascularization and ear sponges), ex vivo (mouse lymphatic rings and rat mesentery explants), and in vitro (proliferation, tubulogenesis, wound-healing, Boyden chambers, and spheroids) assays was used to give insight into the lymphangiogenic steps affected by AD0157. Finally, we investigated the molecular pathways controlled by this drug.ResultsAD0157 was found to inhibit the growth of human breast cancer xenografts in mice, to strongly reduce tumor-associated lymphangiogenesis and to block metastatic dissemination to both lymph nodes and distant organs. The high anti-lymphangiogenic potency of AD0157 was further supported by its inhibitory activity at low micromolar range in two in vivo pathological models and in two ex vivo assays. In addition, AD0157 inhibited lymphatic endothelial cell proliferation, migration and invasion, cellular sprouting, and tube formation. Mechanistically, this compound induced apoptosis in lymphatic endothelial cells and decreased VEGFR-3/-2, ERK1/2, and Akt phosphorylations.ConclusionsThese findings demonstrate the suitability of AD0157 to suppress tumor-associated lymphangiogenesis. Beyond discovering a new potent anti-lymphangiogenic drug that is worth considering in future clinical settings, our study supports the interest of designing anti-lymphangiogenic therapies to avoid distant metastatic processes.

Modeling pre-metastatic lymphvascular niche in the mouse ear sponge assay

Lymphangiogenesis, the formation of new lymphatic vessels, occurs in primary tumors and in draining lymph nodes leading to pre-metastatic niche formation. Reliable in vivo models are becoming instrumental for investigating alterations occurring in lymph nodes before tumor cell arrival. In this study, we demonstrate that B16F10 melanoma cell encapsulation in a biomaterial, and implantation in the mouse ear, prevents their rapid lymphatic spread observed when cells are directly injected in the ear. Vascular remodeling in lymph nodes was detected two weeks after sponge implantation, while their colonization by tumor cells occurred two weeks later. In this model, a huge lymphangiogenic response was induced in primary tumors and in pre-metastatic and metastatic lymph nodes. In control lymph nodes, lymphatic vessels were confined to the cortex. In contrast, an enlargement and expansion of lymphatic vessels towards paracortical and medullar areas occurred in pre-metastatic lymph nodes. We designed an original computerized-assisted quantification method to examine the lymphatic vessel structure and the spatial distribution. This new reliable and accurate model is suitable for in vivo studies of lymphangiogenesis, holds promise for unraveling the mechanisms underlying lymphatic metastases and pre-metastatic niche formation in lymph nodes, and will provide new tools for drug testing.

A specific immune and lymphatic profile characterizes the pre-metastatic state of the sentinel lymph node in patients with early cervical cancer

ABSTRACT The lymph node (LN) pre-metastatic niche is faintly characterized in lymphophilic human neoplasia, although LN metastasis is considered as the strongest prognostic marker of patient survival. Due to its specific dissemination through a complex bilateral pelvic lymphatic system, early cervical cancer is a relevant candidate for investigating the early nodal metastatic process. In the present study, we analyzed in-depth both the lymphatic vasculature and the immune climate of pre-metastatic sentinel LN (SLN), in 48 cases of FIGO stage IB1 cervical neoplasms. An original digital image analysis methodology was used to objectively determine whole slide densities and spatial distributions of immunostained structures. We observed a marked increase in lymphatic vessel density (LVD) and a specific capsular and subcapsular distribution in pre-metastatic SLN when compared with non-sentinel counterparts. Such features persisted in the presence of nodal metastatic colonization. The inflammatory profile attested by CD8+, Foxp3, CD20 and PD-1expression was also significantly increased in pre-metastatic SLN. Remarkably, the densities of CD20+ B cells and PD-1 expressing germinal centers were positively correlated with LVD. All together, these data strongly support the existence of a pre-metastatic dialog between the primary tumor and the first nodal relay. Both lymphatic and immune responses contribute to the elaboration of a specific pre-metastatic microenvironment in human SLN. Moreover, this work provides evidence that, in the context of early cervical cancer, a pre-metastatic lymphangiogenesis occurs within the SLN (pre-metastatic niche) and is associated with a specific humoral immune response.

Nuclear localization of glutamate-cysteine ligase is associated with proliferation in head and neck squamous cell carcinoma

Glutathione (GSH) is the keystone of the cellular response toward oxidative stress. Elevated GSH content correlates with increased resistance to chemotherapy and radiotherapy of head and neck (HN) tumors. The purpose of the present cross-sectional study was to evaluate whether the expression of glutamate-cysteine ligase (GCL) accounts for the increased GSH availability observed in HN squamous cell carcinoma (SCC). For that purpose, the messenger (m)RNA levels of the modifier (M) and catalytic (C) subunits of GCL and its putative regulators (namely, nuclear factor erythroid 2-related factor 2, heme oxygenase-1 and nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha) were monitored in 35 surgical resections of untreated HNSCC. The localization of GCLM was evaluated using in situ hybridization and immunohistochemistry. GCLM expression was significantly increased in tumor samples, compared with normal mucosa, both at the mRNA and protein level (P=0.029), but the pathway of GCLM activation remains to be elucidated. Protein expression of GCLM was detected in the cytoplasm and nucleus. GCLM and the proliferation marker Ki-67 displayed a similar distribution, being both mainly expressed at the periphery of tumor lobules. The present study reported increased expression of GCL and the rate-limiting enzyme of GSH synthesis, within HNSCC. The nuclear localization of GCLM and the concomitant expression of Ki-67 suggested that the localization of GSH synthesis contributes to the protection against oxidative stress within hotspots of cell proliferation.

Tumor Angiogenesis and Lymphangiogenesis: Microenvironmental Soil for Tumor Progression and Metastatic Dissemination

Growing tumors induce changes in their microenvironments that support tumor growth and cancer cell spreading to distant organs. One major change is the induction of angiogenesis and lymphangiogenesis, which are the formation of new blood or lymphatic vessels from preexisting ones, respectively. Metastasis is the main cause of death for cancer patients, and in order to metastasize, tumor cells must first migrate toward blood or lymphatic vessels and intravasate into these vessels. Newly formed tumor blood vessels display incomplete basement membrane, loosely associated pericytes, and leaky cell–cell junctions. The resulting hyperpermeability of tumor blood vessels facilitates tumor intravasation and creates a microenvironment characterized by hypoxia, acidity, and a high interstitial fluid pressure. These abnormalities affect immune cell infiltration, survival, and function favoring tumor growth. The rise of the interstitial fluid pressure leads to an increase of the draining flow from the tumor to the draining lymph node enhancing the attraction of tumor cells toward lymphatic vessels as well as their dissemination into the sentinel lymph node. The entry of tumor cells into lymphatic vessels is favored by chemokine gradients and by the architecture of these vessels. Both lymphangiogenesis and angiogenesis not only occur at the primary site but also at the metastatic sites allowing the development of tumor cells at the secondary site. Nowadays, lymphangiogenesis and angiogenesis are clearly considered as therapeutic targets to prevent tumor growth and metastasis.