Purpose: Cannabinoids have been recently proposed as a new family of potential antitumor agents. The present study was undertaken to investigate the expression of the two cannabinoid receptors, CB 1 and CB 2 , in colorectal cancer and to provide new insight into the molecular pathways underlying the apoptotic activity induced by their activation. Experimental Design: Cannabinoid receptor expression was investigated in both human cancer specimens and in the DLD-1 and HT29 colon cancer cell lines. The effects of the CB 1 agonist arachinodyl-2'-chloroethylamide and the CB 2 agonist N-cyclopentyl-7-methyl-1-(2-morpholin-4-ylethyl)-1,8-naphthyridin-4(1H)-on-3-carboxamide (CB13) on tumor cell apoptosis and ceramide and tumor necrosis factor (TNF)-a production were evaluated. The knockdown of TNF-a mRNA was obtained with the use of selective small interfering RNA. Results: We show that the CB 1 receptor was mainly expressed in human normal colonic epithelium whereas tumor tissue was strongly positive for the CB 2 receptor. The activation of the CB 1 and, more efficiently, of the CB 2 receptors induced apoptosis and increased ceramide levels in the DLD-1 and HT29 cells. Apoptosis was prevented by the pharmacologic inhibition of ceramide de novo synthesis. The CB 2 agonist CB13 also reduced the growth of DLD-1 cells in a mouse model of colon cancer. The knockdown of TNF-a mRNA abrogated the ceramide increase and, therefore, the apoptotic effect induced by cannabinoid receptor activation.Conclusions: The present study shows that either CB 1 or CB 2 receptor activation induces apoptosis through ceramide de novo synthesis in colon cancer cells. Our data unveiled, for the first time, thatTNF-a acts as a link between cannabinoid receptor activation and ceramide production.

Because cells are constantly exposed to micro-environmental changes, they require the ability to adapt to maintain a dynamic equilibrium. Proteins are considered critical for the regulation of gene expression, which is a fundamental process in determining the cellular responses to stimuli. Recently, revolutionary findings in RNA research and the advent of high-throughput genomic technologies have revealed a pervasive transcription of the human genome, which generates many long non-coding RNAs (lncRNAs) whose roles are largely undefined. However, there is evidence that lncRNAs are involved in several cellular physiological processes such as adaptation to stresses, cell differentiation, maintenance of pluripotency and apoptosis. The correct balance of lncRNA levels is crucial for the maintenance of cellular equilibrium, and the dysregulation of lncRNA expression is linked to many disorders; certain transcripts are useful prognostic markers for some of these pathologies. This review revisits the classic concept of cellular homeostasis from the perspective of lncRNAs specifically to understand how this novel class of molecules contributes to cellular balance and how its dysregulated expression can lead to the onset of pathologies such as cancer.

Cyclooxygenase (COX)-2 and 5-lipoxygenase (5-LOX) are key enzymes involved in arachidonic acid metabolism. Their products, prostaglandins and leukotrienes, are involved in colorectal tumor development. We aimed at evaluating whether combined blocking of the COX-2 and 5-LOX pathways might have additive antitumor effects in colorectal cancer. The expression/activity of COX-2 and 5-LOX were assessed in 24 human colorectal cancer specimens. The effects of the COX-2 inhibitor celecoxib and the 5-LOX inhibitor MK886 on prostaglandin E 2 and cysteinyl leukotriene production, tumor cell proliferation, cell apoptosis, and Bcl-2/Bax expression were evaluated in the Caco-2 and HT29 colon cancer cells. We also investigated the effect of the enzymatic inhibition on mitochondrial membrane depolarization, one of the most important mechanisms involved in ceramide-induced apoptosis. Up-regulation of the COX-2 and 5-LOX pathways was found in the tumor tissue in comparison with normal colon mucosa. Inhibition of either COX-2 or 5-LOX alone resulted in activation of the other pathway in colon cancer cells. Combined treatment with 10 Mmol/L celecoxib and MK886 could prevent this activation and had additive effects on inhibiting tumor cell proliferation, inducing cell apoptosis, decreasing Bcl-2 expression, increasing Bax expression, and determining mitochondrial depolarization in comparison with treatment with either inhibitor alone. The administration of the ceramide synthase inhibitor fumonisin B1 could prevent some of these antineoplastic effects. In conclusion, our study showed that inhibition of 5-LOX by MK886 could augment the antitumor activity of celecoxib in human colorectal cancer. [Mol Cancer Ther 2006;5(11):2716 -26]

The communication reports the use of liquid crystalline networks (LCNs) for engineering tissue cultures with human cells. Their ability as cell scaffolds for different cell lines is demonstrated. Preliminary assessments of the material biocompatibility are performed on human dermal fibroblasts and murine muscle cells (C2C12), demonstrating that coatings or other treatments are not needed to use the acrylate-based materials as support. Moreover, it is found that adherent C2C12 cells undergo differentiation, forming multinucleated myotubes, which show the typical elongated shape, and contain bundles of stress fibers. Once biocompatibility is demonstrated, the same LCN films are used as a substrate for culturing human induced pluripotent stem cell-derived cardiomyocites (hiPSC-CMs) proving that LCNs are capable to develop adult-like dimensions and a more mature cell function in a short period of culture in respect to standard supports. The demonstrated biocompatibility together with the extraordinary features of LCNs opens to preparation of complex cell scaffolds, both patterned and stimulated, for dynamic cell culturing. The ability of these materials to improve cell maturation and differentiation will be developed toward engineered heart and skeletal muscular tissues exploring regenerative medicine toward bioartificial muscles for injured sites replacement.

There is growing evidence to suggest that bone marrow‐derived mesenchymal stem cells (BM‐MSCs) are key players in tumour stroma. Here, we investigated the cross‐talk between BM‐MSCs and osteosarcoma (OS) cells. We revealed a strong tropism of BM‐MSCs towards these tumour cells and identified monocyte chemoattractant protein (MCP)‐1, growth‐regulated oncogene (GRO)‐α and transforming growth factor (TGF)‐β1 as pivotal factors for BM‐MSC chemotaxis. Once in contact with OS cells, BM‐MSCs trans‐differentiate into cancer‐associated fibroblasts, further increasing MCP‐1, GRO‐α, interleukin (IL)‐6 and IL‐8 levels in the tumour microenvironment. These cytokines promote mesenchymal to amoeboid transition (MAT), driven by activation of the small GTPase RhoA, in OS cells, as illustrated by the in vitro assay and live imaging. The outcome is a significant increase of aggressiveness in OS cells in terms of motility, invasiveness and transendothelial migration. In keeping with their enhanced transendothelial migration abilities, OS cells stimulated by BM‐MSCs also sustain migration, invasion and formation of the in vitro capillary network of endothelial cells. Thus, BM‐MSC recruitment to the OS site and the consequent cytokine‐induced MAT are crucial events in OS malignancy.