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Highly immunogenic cancers such as malignant melanoma are capable of inexorable tumor growth despite the presence of antitumor immunity. Thus, only a restricted minority of tumorigenic malignant cells may possess the phenotypic and functional characteristics needed to modulate tumor-directed immune activation. Here we provide evidence supporting this hypothesis. Tumorigenic ABCB5 + malignant melanoma initiating cells

Background:The aim of this study was to elucidate the prognostic impact of putative cancer stem cell markers CD133, CD166, CD44s, EpCAM, and aldehyde dehydrogenase-1 (ALDH1) in colorectal cancer.Methods:A tissue microarray of 1420 primary colorectal cancers and 57 normal mucosa samples was immunostained for CD133, CD166, CD44s, EpCAM, and ALDH1 in addition to 101 corresponding whole tissue sections. Invasive potential of three colorectal cancer cell lines was tested.Results:Differences between normal tissue and cancer were observed for all markers (P<0.001). Loss of membranous CD166 and CD44s were linked to higher pT (P=0.002, P=0.014), pN (P=0.004, P=0.002), an infiltrating growth pattern (P<0.001, P=0.002), and worse survival (P=0.015, P=0.019) in univariate analysis only. Loss of membranous EpCAM expression was also linked to higher pN (P=0.023) and infiltrating growth pattern (P=0.005). The CD44s, CD166, and EpCAM expression were lost towards the invasive front. The CD44−/CD166− cells from three colorectal cancer cell lines exhibited significantly higher invasive potential in vitro than their positive counterparts.Conclusions:Loss, rather than overexpression, of membranous CD44s, CD166, and EpCAM is linked to tumour progression. This supports the notion that the membranous evaluation of these proteins assessed by immunohistochemistry may be representative of their cell adhesion rather than their intra-cellular functions.

Growth in three-dimensional (3D) architectures has been suggested to play an important role in tumor expansion and in the resistance of cancers to treatment with drugs or cytokines or irradiation. To obtain an insight into underlying molecular mechanisms, we addressed gene expression profiles of NA8 melanoma cells cultured in bidimensional monolayers (2D) or in 3D multicellular tumor spheroids (MCTS). MCTS containing 10-30,000 cells were generated upon overnight culture in poly-Hydroxyethylmethacrylate (polyHEMA) coated plates. Kinetics of cell proliferation in MCTS was significantly slower than in monolayer cultures. Following long-term culture (>10 days), however, MCTS showed highly compact and organised cell growth in outer layers, with necrotic cores. Oligonucleotide microarray analysis of the expression of over 20,000 genes was performed on cells cultured in standard 2D, in the presence of collagen as model of extracellular matrix (ECM), or in MCTS. Gene expression profiles of cells cultured in 2D in the presence or absence of ECM were highly similar, with >/=threefold differences limited to five genes. In contrast, culture in MCTS resulted in the significant, >/=threefold, upregulation of the expression of >100 transcripts while 73 were >/=threefold downregulated. In particular, genes encoding CXCL1, 2, and 3 (GRO-alpha, -beta, and gamma), IL-8, CCL20 (MIP-3alpha), and Angiopoietin-like 4 were significantly upregulated, whereas basic FGF and CD49d encoding genes were significantly downregulated. Oligonucleotide chip data were validated at the gene and protein level by quantitative real-time PCR, ELISA, and cell surface staining assays. Taken together, our data indicate that structural modifications of the architecture of tumor cell cultures result in a significant upregulation of the expression of a number of genes previously shown to play a role in melanoma progression and metastatic process.

Our results provide evidence that gene patterns related to chondrocyte differentiation discriminate between CTR and OA human cartilage with higher sensitivity than single ECM genes. The method described here has the potential to improve understanding of the progression of OA and could become a valuable diagnostic tool.

Culture of cancerous cells in standard monolayer conditions poorly mirrors growth in three-dimensional architectures typically observed in a wide majority of cancers of different histological origin. Multicellular tumor spheroid (MCTS) culture models were developed to mimic these features. However, in vivo tumor growth is also characterized by the presence of ischemic and necrotic areas generated by oxygenation gradients and differential access to nutrients. Hypoxia and necrosis play key roles in tumor progression and resistance to treatment. To provide in vitro models recapitulating these events in highly controlled and standardized conditions, we have generated colorectal cancer (CRC) cell spheroids of different sizes and analyzed their gene expression profiles and sensitivity to treatment with 5FU, currently used in therapeutic protocols. Here we identify three MCTS stages, corresponding to defined spheroid sizes, characterized by normoxia, hypoxia, and hypoxia plus necrosis, respectively. Importantly, we show that MCTS including both hypoxic and necrotic areas most closely mimic gene expression profiles of in vivo-developing tumors and display the highest resistance to 5FU. Taken together, our data indicate that MCTS may mimic in vitro generation of ischemic and necrotic areas in highly standardized and controlled conditions, thereby qualifying as relevant models for drug screening purposes.

Gut microbiota stimulate chemokine production by CRC cells, thus favouring recruitment of beneficial T cells into tumour tissues.

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