Copresentation of BMP-6 and RGD Ligands Enhances Cell Adhesion and BMP-Mediated Signaling.

We report on the covalent immobilization of bone morphogenetic protein 6 (BMP-6) and its co-presentation with integrin ligands on a nanopatterned platform to study cell adhesion and signaling responses which regulate the transdifferentiation of myoblasts into osteogenic cells. To immobilize BMP-6, the heterobifunctional linker MU-NHS is coupled to amine residues of the growth factor; this prevents its internalization while ensuring that its biological activity is maintained. Additionally, to allow cells to adhere to such platform and study signaling events arising from the contact to the surface, we used click-chemistry to immobilize cyclic-RGD carrying an azido group reacting with PEG-alkyne spacers via copper-catalyzed 1,3-dipolar cycloaddition. We show that the copresentation of BMP-6 and RGD favors focal adhesion formation and promotes Smad 1/5/8 phosphorylation. When presented in low amounts, BMP-6 added to culture media of cells adhering to the RGD ligands is less effective than BMP-6 immobilized on the surfaces in inducing Smad complex activation and in inhibiting myotube formation. Our results suggest that a local control of ligand density and cell signaling is crucial for modulating cell response.

Early events in foamy virus-host interaction and intracellular trafficking.

Here we review viral and cellular requirements for entry and intracellular trafficking of foamy viruses (FVs) resulting in integration of viral sequences into the host cell genome. The virus encoded glycoprotein harbors all essential viral determinants, which are involved in absorption to the host membrane and triggering the uptake of virus particles. However, only recently light was shed on some details of FV's interaction with its host cell receptor(s). Latest studies indicate glycosaminoglycans of cellular proteoglycans, particularly heparan sulfate, to be of utmost importance. In a species-specific manner FVs encounter endogenous machineries of the target cell, which are in some cases exploited for fusion and further egress into the cytosol. Mostly triggered by pH-dependent endocytosis, viral and cellular membranes fuse and release naked FV capsids into the cytoplasm. Intact FV capsids are then shuttled along microtubules and are found to accumulate nearby the centrosome where they can remain in a latent state for extended time periods. Depending on the host cell cycle status, FV capsids finally disassemble and, by still poorly characterized mechanisms, the preintegration complex gets access to the host cell chromatin. Host cell mitosis finally allows for viral genome integration, ultimately starting a new round of viral replication.

Metronomic treatment with low-dose trofosfamide leads to a long-term remission in a patient with docetaxel-refractory advanced metastatic prostate cancer.

The treatment of metastatic prostate cancer patients refractory to androgen withdrawal and docetaxel therapy is currently discouraging and new therapeutic approaches are vastly needed. Here, we report a long-term remission over one year in a 68-year-old patient with metastatic docetaxel-refractory prostate cancer employing low-dose trofosfamide. The patient suffered from distant failure with several bone lesions and lymph node metastases depicted by a (11) C-Choline positron emission tomography/computerized tomography (PET/CT). After initiation of trofosfamide 100 mg taken orally once a day we observed a steadily decreasing PSA value from initial 46.6 down to 2.1 mug/L. The Choline-PET/CT was repeated after 10 months of continuous therapy and demonstrated a partial remission of the bone lesions and a regression of all involved lymph nodes but one. Taken together we found an astonishing and durable activity of the alkylating agent trofosfamide given in a metronomic fashion. We rate the side effects as low and state an excellent therapeutic ratio of this drug in our patient.