Pressure control in interfacial systems: Atomistic simulations of vapor nucleation.

A large number of phenomena of scientific and technological interest involve multiple phases and occur at constant pressure of one of the two phases, e.g., the liquid phase in vapor nucleation. It is therefore of great interest to be able to reproduce such conditions in atomistic simulations. Here we study how popular barostats, originally devised for homogeneous systems, behave when applied straightforwardly to heterogeneous systems. We focus on vapor nucleation from a super-heated Lennard-Jones liquid, studied via hybrid restrained Monte Carlo simulations. The results show a departure from the trends predicted for the case of constant liquid pressure, i.e., from the conditions of classical nucleation theory. Artifacts deriving from standard (global) barostats are shown to depend on the size of the simulation box. In particular, for Lennard-Jones liquid systems of 7000 and 13 500 atoms, at conditions typically found in the literature, we have estimated an error of 10-15 kBT on the free-energy barrier, corresponding to an error of 104-106 s-1σ-3 on the nucleation rate. A mechanical (local) barostat is proposed which heals the artifacts for the considered case of vapor nucleation.

Therapeutic targeting of membrane-associated GRP78 in leukemia and lymphoma: preclinical efficacy in vitro and formal toxicity study of BMTP-78 in rodents and primates.

Translation of drug candidates into clinical settings requires demonstration of preclinical efficacy and formal toxicology analysis for filling an Investigational New Drug (IND) application with the US Food and Drug Administration (FDA). Here, we investigate the membrane-associated glucose response protein 78 (GRP78) as a therapeutic target in leukemia and lymphoma. We evaluated the efficacy of the GRP78-targeted proapoptotic drug bone metastasis targeting peptidomimetic 78 (BMTP-78), a member of the D(KLAKLAK)2-containing class of agents. BMTP-78 was validated in cells from patients with acute myeloid leukemia and in a panel of human leukemia and lymphoma cell lines, where it induced dose-dependent cytotoxicity in all samples tested. Based on the in vitro efficacy of BMTP-78, we performed formal good laboratory practice toxicology studies in both rodents (mice and rats) and nonhuman primates (cynomolgus and rhesus monkeys). These analyses represent required steps towards an IND application of BMTP-78 for theranostic first-in-human clinical trials.

Luminescent silica nanoparticles for cancer diagnosis.

Fluorescence imaging techniques are becoming essential for preclinical investigations, necessitating the development of suitable tools for in vivo measurements. Nanotechnology entered this field to help overcome many of the current technical limitations, and luminescent nanoparticles (NPs) are one of the most promising materials proposed for future diagnostic implementation. NPs also constitute a versatile platform that can allow facile multi-functionalization to perform multimodal imaging or theranostics (simultaneous diagnosis and therapy). In this contribution we have mainly focused on dye doped silica or silica-based NPs conjugated with targeting moieties to enable imaging of specific cancer cells. We also cite and briefly discuss a few non-targeted systems for completeness. We summarize common synthetic approaches to these materials, and then survey the most recent imaging applications of silica-based nanoparticles in cancer. The field of theranostics is particularly important and stimulating, so, even though it is not the central topic of this paper, we have included some significant examples. We conclude with a short section on NP-based systems already in clinical trials and examples of specific applications in childhood tumors. This review aims to describe and discuss, through focused examples, the great potential of these materials in the medical field, with the aim to encourage further research to implement applications, which today are still rare.

Vascular endothelial growth factor-C stimulates the migration and proliferation of Kaposi's sarcoma cells.

Recent evidence suggesting vascular endothelial growth factor-C (VEGF-C), which is a regulator of lymphatic and vascular endothelial development, raised the question whether this molecule could be involved in Kaposi's sarcoma (KS), a strongly angiogenic and inflammatory tumor often associated with infection by human immunodeficiency virus-1. This disease is characterized by the presence of a core constituted of three main populations of "spindle" cells, having the features of lymphatic/vascular endothelial cells, macrophagic/dendritic cells, and of a mixed macrophage-endothelial phenotype. In this study we evaluated the biological response of KS cells to VEGF-C, using an immortal cell line derived from a KS lesion (KS IMM), which retains most features of the parental tumor and can induce KS-like sarcomas when injected subcutaneously in nude mice. We show that VEGFR-3, the specific receptor for VEGF-C, is expressed by KS IMM cells grown in vitro and in vivo. In vitro, VEGF-C induces the tyrosine phosphorylation of VEGFR-2, a receptor also for VEGF-A, as well as that of VEGFR-3. The activation of these two receptors in KS IMM cells is followed by a dose-responsive mitogenic and motogenic response. The stimulation of KS IMM cells with a mutant VEGF-C unable to bind and activate VEFGR-2 resulted in no proliferative response and in a weak motogenic stimulation, suggesting that VEGFR-2 is essential in transducing a proliferative signal and cooperates with VEGFR-3 in inducing cell migration. Our data add new insights on the pathogenesis of KS, suggesting that the involvement of endothelial growth factors may not only determine KS-associated angiogenesis, but also play a critical role in controlling KS cell growth and/or migration and invasion.

c-fos-induced growth factor/vascular endothelial growth factor D induces angiogenesis in vivo and in vitro.

c-fos-induced growth factor/vascular endothelial growth factor D (Figf/Vegf-D) is a secreted factor of the VEGF family that binds to the vessel and lymphatic receptors VEGFR-2 and VEGFR-3. Here we report that Figf/Vegf-D is a potent angiogenic factor in rabbit cornea in vivo in a dose-dependent manner. In vitro Figf/Vegf-D induces tyrosine phosphorylation of VEGFR-2 and VEGFR-3 in primary human umbilical cord vein endothelial cells (HUVECs) and in an immortal cell line derived from Kaposi's sarcoma lesion (KS-IMM). The treatment of HUVECs with Figf/Vegf-D induces dose-dependent cell growth. Figf/VEGF-D also induces HUVEC elongation and branching to form an extensive network of capillary-like cords in three-dimensional matrix. In KS-IMM cells Figf/Vegf-D treatment results in dose-dependent mitogenic and motogenic activities. Taken together with the previous observations that Figf/Vegf-D expression is under the control of the nuclear oncogene c-fos, our data uncover a link between a nuclear oncogene and angiogenesis, suggesting that Figf/Vegf-D may play a critical role in tumor cell growth and invasion.

Overexpression of the RON gene in human breast carcinoma.

Constitutive activation of the RON gene, known to code for the tyrosine-kinase receptor for Macrophage Stimulating Protein (also known as Scatter Factor 2), has been shown to induce invasive-metastatic phenotype in vitro. As yet, nothing is known about the expression of this novel member of the MET-oncogene family in spontaneously occurring human cancers. Here we report that Ron is expressed at abnormally high levels in about 50% primary breast carcinomas (35/74 patients). Among these, the expression is increased more than 20-fold in 12 cases and the overexpressed protein is constitutively phosphorylated on tyrosine residues. Notably, Ron is only barely detectable in epithelial cells of the mammary gland, and its expression remains unchanged in benign breast lesions (including adenomas and papillomas). Overexpression was observed in different histotypic variants of carcinomas; it is associated with the disease at any stage and correlates with the post-menopausal status. In breast carcinoma cells grown in vitro, activation of the Ron receptor resulted in proliferation, migration and invasion through reconstituted basement membranes. Altogether, these data suggest a role for the RON gene in progression of human breast carcinomas to the invasive-metastatic phenotype.