Immunological monitoring for prediction of clinical response to antitumor vaccine therapy.

Immunotherapy has shown promising results in a variety of cancers, including melanoma. However, the responses to therapy are usually heterogeneous, and understanding the factors affecting clinical outcome is still not achieved. Here, we show that immunological monitoring of the vaccine therapy for melanoma patients may help to predict the clinical course of the disease. We studied cytokine profile of cellular Th1 (IL-2, IL-12, IFN-γ) and humoral Th2 (IL-4, IL-10) immune response, vascular endothelial growth factor (VEGFA), transforming growth factor-ß 2 (TGF-ß 2), S100 protein (S100A1B and S100BB), adhesion molecule CD44 and serum cytokines ß2-microglobulin to analyze different peripheral blood mononuclear cell subpopuations of patients treated with dendritic vaccines and/or cyclophosphamide in melanoma patients in the course of adjuvant treatment. The obtained data indicate predominance of cellular immunity in the first adjuvant group of patients with durable time to progression and shift to humoral with low cellular immunity in patients with short-term period to progression (increased levels of IL-4 and IL- 10). Beta-2 microglobulin was differentially expressed in adjuvant subgroups: its higher levels correlated with shorter progression-free survival and the total follow-up time. Immunoregulatory index was overall higher in patients with disease progression compared to the group of patients with no signs of disease progression.

Three-dimensional in vivo imaging of tumors expressing red fluorescent proteins.

3D imaging of genetically-engineered fluorescent tumors enables quantitative monitoring of tumor growth/regression, metastatic processes, including during anticancer therapy in real-time.Fluorescent tumor models for 3D imaging require stable expression of genetically encoded fluorescent proteins and maintenance of the properties of tumor cell line including growth rate, morphology, and immunophenotype.In this chapter, the protocol for 3D imaging of tumors expressing red fluorescent protein are described in detail.

Cancer/testis genes expression in human melanoma cell lines.

We analyzed the expression of 15 cancer/testis and four melanoma differentiation antigens in 21 metastatic melanoma cell lines using reverse transcriptase-polymerase chain reaction (RT-PCR) assay. On the basis of morphological characteristics, tumor cell lines were divided into three groups with high, moderate, and low grade of differentiation. Evaluation of gene expression and melanoma cell morphology has revealed a correlation between increased expression of cancer/testis genes and differentiation grade of cancer cells. The gene expression pattern for lymph node metastases and primary tumors exhibits the distribution of expression level and frequency similar to that found for established cell lines. Nevertheless, only 60% lymph node metastases or primary tumor tissue of randomly selected patients show marked expression of the most prominent cancer/testis genes, and almost 90% lesion tissue expresses at least one of 15 cancer/testis genes.

Melanoma vasculogenic mimicry is strongly related to reactive oxygen species level.

The concept of 'vasculogenic mimicry' (VM) was introduced to describe the unique ability of highly invasive tumor cells to form capillary-like structures (CLS) and matrix-rich patterned network in three-dimensional culture that mimic embryonic vasculogenic network. Recently, we have shown that CLS formation requires apoptotic cell death through activation of caspase-3-dependent mechanism. In this study, to identify some molecular determinants driving aggressive melanoma cells to express a latent 'angiogenic program' that recapitulates the early events of CLS formation, we focused on the involvement of antioxidants (AOs) in the process of melanoma VM. We have studied the effects of resveratrol, (-)-epigallocathechin gallate, N-acetyl-cysteine (NAC) and Trolox on the ability of melanoma cells to form/destroy CLS. We observed that the formation of CLS was strongly related to reactive oxygen species level. In vivo animal experiments confirmed the involvement of reactive oxygen species level in melanoma VM. To understand the molecular mechanisms of this phenomenon, we specifically looked for induction of apoptosis and vascular endothelial growth factor (VEGF) release. Western blot analysis revealed that the level of VEGF, VEGF receptors (VEGF-Rs) and active caspase-3 dramatically decreased in cells treated with AOs. Here, we also report further experiments designed to determine whether the crosstalk between AOs and apoptosis exists in melanoma VM.

The involvement of apoptosis in melanoma vasculogenic mimicry.

During development, the formation and remodeling of the primary vascular network occurs by vasculogenesis and angiogenesis. In 1999, the concept of vasculogenic mimicry was introduced to describe the unique ability of highly aggressive tumor cells to form a capillary-like structure and a matrix-rich patterned network in three-dimensional culture that mimic the embryonic vasculogenic network. In this study, we examined the ability of melanoma cells derived from patients with disseminated melanoma to engage in vasculogenic mimicry in order to identify key parameters in the complexity of the formation of capillary-like structure. We showed that disseminated melanoma as well as uveal and cutaneous melanoma adopts a vascular-related phenotype and engages in vasculogenic mimicry: the main geometrical features of capillary-like structure are determined during the first step of the vascular network assembly. We provided experimental evidence that capillary-like structure formation requires apoptotic cell death through activation of a caspase-dependent mechanism: a broad range caspase inhibitor zVAD-fmk and a caspase-3 inhibitor DEVD blocked capillary-like structure formation. Apoptosis occurs before capillary-like structure formation but not after capillary-like structures have assembled. These observations may provide a better understanding of the mechanisms involved in melanoma vasculogenic mimicry.