Contribution of mutant HSC clones to immature and mature cells in MDS and CMML, and variations with AZA therapy

Myelodysplastic neoplasms (MDSs) and chronic myelomonocytic leukemia (CMML) are clonal disorders driven by progressively acquired somatic mutations in hematopoietic stem cells (HSCs). Hypomethylating agents (HMAs) can modify the clinical course of MDS and CMML. Clinical improvement does not require eradication of mutated cells and may be related to improved differentiation capacity of mutated HSCs. However, in patients with established disease it is unclear whether (1) HSCs with multiple mutations progress through differentiation with comparable frequency to their less mutated counterparts or (2) improvements in peripheral blood counts following HMA therapy are driven by residual wild-type HSCs or by clones with particular combinations of mutations. To address these questions, the somatic mutations of individual stem cells, progenitors (common myeloid progenitors, granulocyte monocyte progenitors, and megakaryocyte erythroid progenitors), and matched circulating hematopoietic cells (monocytes, neutrophils, and naïve B cells) in MDS and CMML were characterized via high-throughput single-cell genotyping, followed by bulk analysis in immature and mature cells before and after AZA treatment. The mutational burden was similar throughout differentiation, with even the most mutated stem and progenitor clones maintaining their capacity to differentiate to mature cell types in vivo. Increased contributions from productive mutant progenitors appear to underlie improved hematopoiesis in MDS following HMA therapy.

Glycopeptide dendrimer colchicine conjugates targeting cancer cells

Screening of a 65,536-member one-bead-one-compound (OBOC) combinatorial library of glycopeptide dendrimers of structure ((betaGal)(n)(+1)X(8)X(7)X(6)X(5))(2)DapX(4)X(3)X(2)X(1)(beta-Gal)(m) (betaGal=beta-galactosyl-thiopropionic acid, X(8-1)=variable amino acids, Dap=l-2,3-diaminopropionic acid, n, m=0, or 1 if X(8)=Lys resp. X(1)=Lys) for binding of Jurkat cells to the library beads in cell culture, resynthesis and testing lead to the identification of dendrimer J1 (betaGal-Gly-Arg-His-Ala)(2)Dap-Thr-Arg-His-Asp-CysNH(2) and related analogues as delivery vehicles. Cell targeting is evidenced by FACS with fluorescein conjugates such as J1F. The colchicine conjugate J1C is cytotoxic with LD(50)=1.5 microM. The beta-galactoside groups are necessary for activity, as evidenced by the absence of cell-binding and cytotoxicity in the non-galactosylated, acetylated analogue AcJ1F and AcJ1C, respectively. The pentagalactosylated dendrimer J4 betaGal(4)(Lys-Arg-His-Leu)(2)Dap-Thr-Tyr-His-Lys(betaGal)-Cys) selectively labels Jurkat cell as the fluorescein derivative J4F, but its colchicine conjugate J4C lacks cytotoxicity. Tubulin binding assays show that the colchicine dendrimer conjugates do not bind to tubulin, implying intracellular degradation of the dendrimers releasing the active drug.

Neoglycopeptide dendrimer libraries as a source of lectin binding ligands

[structure: see text] A 15 625-membered peptide dendrimer combinatorial library was acylated with an alpha-C-fucosyl residue at its four N-termini and screened for binding to fucose-specific lectins. Dendrimer FD2 (Fuc-alpha-CH2CO-Lys-Pro-Leu)4(Lys-Phe-Lys-Ile)2Lys-His-Ile-NH2 was identified as a potent ligand against Ulex europaeus lectin UEA-I (IC50 = 11 microM) and Pseudomonas aeruginosa lectin PA-IIL (IC50 = 0.14 microM).