Apoptotic cell and phagocyte interplay: recognition and consequences in different cell systems

Cell death by apoptosis is characterized by specific biochemical changes, including the exposure of multiple ligands, expected to tag the dying cell for prompt recognition by phagocytes. In non-pathological conditions, an efficient clearance is assured by the redundant interaction between apoptotic cell ligands and multiple receptor molecules present on the engulfing cell surface. This review concentrates on the molecular interactions operating in mammalian and non-mammalian systems for apoptotic cell recognition, as well as on the consequences of their signaling. Furthermore, some cellular models where the exposure of the phosphatidylserine (PS) phospholipid, a classical hallmark of the apoptotic phenotype, is not followed by cell death will be discussed.

Molecular aspects of prostate cancer: implications for future directions

Many studies have been developed trying to understand the complex molecular mechanisms involved in oncogenesis and progression of prostate cancer (PCa). Current biotechnological methodologies, especially genomic studies, are adding important aspects to this area. The construction of extensive DNA sequence data and gene expression profiles have been intensively explored to search for candidate biomarkers to evaluate PCa. The use of DNA micro-array robotic systems constitutes a powerful approach to simultaneously monitor the expression of a great number of genes. The resulting gene expressing profiles can be used to specifically describe tumor staging and response to cancer therapies. Also, it is possible to follow PCa pathological properties and to identify genes that anticipate the behavior of clinical disease. The molecular pathogenesis of PCa involves many contributing factors, such as alterations in signal transduction pathways, angiogenesis, adhesion molecules expression and cell cycle control. Also, molecular studies are making clear that many genes, scattered through several different chromosomal regions probably cause predisposition to PCa. The discovery of new molecular markers for PCa is another relevant advance resulting from molecular biology studies of prostate tumors. Interesting tissue and serum markers have been reported, resulting in many cases in useful novelties to diagnostic and prognostic approaches to follow-up PCa. Finally, gene therapy comes as an important approach for therapeutic intervention in PCa. Clinical trials for PCa have been demonstrating that gene therapy is relatively safe and well tolerated, although some improvements are yet to be developed.

Parasite signalling by host-derived molecules: facts and hypotheses

A series of descriptions in the literature points to the fact that an interaction between host-derived cytokines and protozoan parasites can play a role in the natural history of a disease. In this paper those examples are reviewed and discussed. In most cases, the host-derived molecules act as growth factors for the parasites, and in one case, protect the infective form from heatinduced death. Since the molecules described act as growth factores or as protectors from death when acting on cells from the host, it is suggested that their mechanism of action is the same, when targeting mammalian cells or protozoan parasites. A hypothesis is formulated that protozoan parasites might adapt to their mammalian host by "mimicking" a host cytokine-dependent system of cell growth and differentiation.