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Background Chronic lymphocytic leukemia (CLL), the most common adulthood leukemia, is characterized by the accumulation of abnormal [CD5.sup.+] B lymphocytes, which results in a progressive failure of the immune system. Despite intense research efforts, drug resistance remains a major cause of treatment failure in CLL, particularly in patients with dysfunctional TP53. The objective of our work was to identify potential approaches that might overcome CLL drug refractoriness by examining the pro-apoptotic potential of targeting the cell surface receptor CD47 with serum-stable agonist peptides. Methods and Findings In peripheral blood samples collected from 80 patients with CLL with positive and adverse prognostic features, we performed in vitro genetic and molecular analyses that demonstrate that the targeting of CD47 with peptides derived from the C-terminal domain of thrombospondin-1 efficiently kills the malignant CLL B cells, including those from high-risk individuals with a dysfunctional TP53 gene, while sparing the normal T and B lymphocytes from the CLL patients. Further studies reveal that the differential response of normal B lymphocytes, collected from 20 healthy donors, and leukemic B cells to CD47 peptide targeting results from the sustained activation in CLL B cells of phospholipase C gamma-1 (PLC[gamma]1), a protein that is significantly over-expressed in CLL. Once phosphorylated at tyrosine 783, PLC[gamma]1 enables a [Ca.sup.2+]-mediated, caspase-independent programmed cell death (PCD) pathway that is not down-modulated by the lymphocyte microenvironment. Accordingly, down-regulation of PLC[gamma]1 or pharmacological inhibition of PLC[gamma]1 phosphorylation abolishes CD47-mediated killing. Additionally, in a CLL-xenograft model developed in NOD/scid gamma mice, we demonstrate that the injection of CD47 agonist peptides reduces tumor burden without inducing anemia or toxicity in blood, liver, or kidney. The limitations of our study are mainly linked to the affinity of the peptides targeting CD47, which might be improved to reach the standard requirements in drug development, and the lack of a CLL animal model that fully mimics the human disease. Conclusions Our work provides substantial progress in (i) the development of serum-stable CD47 agonist peptides that are highly effective at inducing PCD in CLL, (ii) the understanding of the molecular events regulating a novel PCD pathway that overcomes CLL apoptotic avoidance, (iii) the identification of PLC[gamma]1 as an over-expressed protein in CLL B cells, and (iv) the description of a novel peptide-based strategy against CLL., Introduction Chronic lymphocytic leukemia (CLL), a human malignancy caused by an imbalance between proliferation and programmed cell death (PCD) [1], is the most common form of leukemia in adults. CLL [...]

The application of fluorinated diaminocyclopentanes as chiral sensitive NMR probes for a topological footprint of the RNA structure is demonstrated. The study provides evidence for the ability of small fluorinated moderate binders to act as external probes of RNA structures.

The general strategy for the synthesis of beta(super 2)-amino acids starting from alpha-amino acids, via the Reformatsky reaction and Mannich-type iminium electrophile is described. This strategy is of great value for rapid generation of beta(super 2)-amino acids and this method can be scaled up for the industrial production of these compounds.

Development of new methods for the synthesis of β-amino acids is important as polymers of these compounds are promising peptidomimetic candidates in medicinal chemistry. We report here our findings on a new and highly efficient general strategy for the synthesis of β²-amino acids by homologation of α-amino acids, involving the Reformatsky reaction and Mannich-type imminium electrophile. [ABSTRACT FROM AUTHOR]