New derivatives of the antimalarial drug Pyrimethamine in the control of melanoma tumor growth: an in vitro and in vivo study.

BACKGROUND: The antimalarial drug Pyrimethamine has been suggested to exert an antitumor activity by inducing apoptotic cell death in cancer cells, including metastatic melanoma cells. However, the dose of Pyrimethamine to be considered as an anticancer agent appears to be significantly higher than the maximum dose used as an antiprotozoal drug. METHODS: Hence, a series of Pyrimethamine analogs has been synthesized and screened for their apoptosis induction in two cultured metastatic melanoma cell lines. One of these analogs, the Methylbenzoprim, was further analyzed to evaluate cell-cycle and the mechanisms of cell death. The effects of Methylbenzoprim were also analyzed in a severe combined immunodeficiency (SCID)-mouse xenotransplantation model. RESULTS: Low dose of Methylbenzoprim was capable of inducing cytotoxic activity and a potent growth-inhibitory effect by arresting cell cycle in S-phase in melanoma cells. Methylbenzoprim was also detected as powerful antineoplastic agents in SCID-mouse although used at very low dose and as a single agent. CONCLUSIONS: Our screening approach led to the identification of a "low cost" newly synthesized drug (methylbenzoprim), which is able to act as an antineoplastic agent in vitro and in vivo, inhibiting melanoma tumor growth at very low concentrations.

Autophagic flux and autophagosome morphogenesis require the participation of sphingolipids.

Apoptosis and autophagy are two evolutionary conserved processes that exert a critical role in the maintenance of tissue homeostasis. While apoptosis is a tightly regulated cell program implicated in the removal of damaged or unwanted cells, autophagy is a cellular catabolic pathway that is involved in the lysosomal degradation and recycling of proteins and organelles, and is thereby considered an important cytoprotection mechanism. Sphingolipids (SLs), which are ubiquitous membrane lipids in eukaryotes, participate in the generation of various membrane structures, including lipid rafts and caveolae, and contribute to a number of cellular functions such as cell proliferation, apoptosis and, as suggested more recently, autophagy. For instance, SLs are hypothesized to be involved in several intracellular processes, including organelle membrane scrambling, whilst at the plasma membrane lipid rafts, acting as catalytic domains, strongly contribute to the ignition of critical signaling pathways determining cell fate. In particular, by targeting several shared regulators, ceramide, sphingosine-1-phosphate, dihydroceramide, sphingomyelin and gangliosides seem able to differentially regulate the autophagic pathway and/or contribute to the autophagosome formation. This review illustrates recent studies on this matter, particularly lipid rafts, briefly underscoring the possible implication of SLs and their alterations in the autophagy disturbances and in the pathogenesis of some human diseases.

Mitochondria hyperfusion and elevated autophagic activity are key mechanisms for cellular bioenergetic preservation in centenarians.

Mitochondria have been considered for long time as important determinants of cell aging because of their role in the production of reactive oxygen species. In this study we investigated the impact of mitochondrial metabolism and biology as determinants of successful aging in primary cultures of fibroblasts isolated from the skin of long living individuals (LLI) (about 100 years old) compared with those from young (about 27 years old) and old (about 75 years old) subjects. We observed that fibroblasts from LLI displayed significantly lower complex I-driven ATP synthesis and higher production of H2O2 in comparison with old subjects. Despite these changes, bioenergetics of these cells appeared to operate normally. This lack of functional consequences was likely due to a compensatory phenomenon at the level of mitochondria, which displayed a maintained supercomplexes organization and an increased mass. This appears to be due to a decreased mitophagy, induced by hyperfused, elongated mitochondria. The overall data indicate that longevity is characterized by a preserved bioenergetic function likely attained by a successful mitochondria remodeling that can compensate for functional defects through an increase in mass, i.e. a sort of mitochondrial "hypertrophy".