Hemoglobin Is a Co-Factor of Human Trypanosome Lytic Factor

Trypanosome lytic factor (TLF) is a high-density lipoprotein (HDL) subclass providing innate protection to humans against infection by the protozoan parasite Trypanosoma brucei brucei. Two primate-specific plasma proteins, haptoglobin-related protein (Hpr) and apolipoprotein L-1 (ApoL-1), have been proposed to kill T. b. brucei both singularly or when co-assembled into the same HDL. To better understand the mechanism of T. b. brucei killing by TLF, the protein composition of TLF was investigated using a gentle immunoaffinity purification technique that avoids the loss of weakly associated proteins. HDL particles recovered by immunoaffinity absorption, with either anti-Hpr or anti-ApoL-1, were identical in protein composition and specific activity for T. b. brucei killing. Here, we show that TLF-bound Hpr strongly binds Hb and that addition of Hb stimulates TLF killing of T. b. brucei by increasing the affinity of TLF for its receptor, and by inducing Fenton chemistry within the trypanosome lysosome. These findings suggest that TLF in uninfected humans may be inactive against T. b. brucei prior to initiation of infection. We propose that infection of humans by T. b. brucei causes hemolysis that triggers the activation of TLF by the formation of Hpr–Hb complexes, leading to enhanced binding, trypanolytic activity, and clearance of parasites

Novel small molecule drugs inhibit tumor cell metabolism and show potent anti-tumorigenic potential

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C/D-box snoRNA-derived RNA production is associated with malignant transformation and metastatic progression in prostate cancer

Small nucleolar RNAs (snoRNAs) are dynamically regulated in different tissues and affected in disease. SnoRNAs are processed further to stable smaller RNAs. We sequenced the small RNA transcriptome of prostate cancer (PCa) at different PCa stages and generated a quantified catalogue of 3927 small non-coding RNAs (sncRNAs) detected in normal and malignant prostate tissue. From these, only 1524 are microRNAs. The remaining 2401 sncRNAs represent stable sncRNAs species that originate from snoRNA, tRNA and other sncRNAs. We show that snoRNA-derived RNAs (sdRNAs) display stronger differential expression than microRNAs and are massively upregulated in PCa. SdRNAs account for at least one third of all small RNAs with expression changes in tumor compared to normal adjacent tissue. Multiple sdRNAs can be produced from one snoRNA in a manner related to the conservation of structural snoRNA motifs. Q-PCR analysis in an independent patient cohort (n=106) confirmed the processing patterns of selected snoRNAs (SNORD44, SNORD78, SNORD74 and SNORD81) and the cancer-associated up-regulation of their sdRNAs observed in sequencing data. Importantly, expression of SNORD78 and its sdRNA is significantly higher in a subset of patients that developed metastatic disease demonstrating that snoRNA and sdRNAs may present as novel diagnostic and/or prognostic biomarkers for PCa.This article has supplementary files, which can be found here:http://dx.doi.org/10.18632/oncotarget.417

Synthetic lethality between Rb, p53 and Dicer or miR-17-92 in retinal progenitors suppresses retinoblastoma formation.

Synthetic lethality is a promising strategy for specific targeting of cancer cells that carry mutations that are absent in normal cells. This approach may help overcome the challenge associated with targeting dysfunctional tumour suppressors, such as p53 and Rb (refs 1, 2). Here we show that Dicer1 targeting prevents retinoblastoma formation in mice by synthetic lethality with combined inactivation of p53 and Rb. Although Dicer1 functions as a haploinsufficient tumour suppressor, its complete loss of function is selected against during tumorigenesis(3-5). We show that Dicer1 deficiency is tolerated in Rb-deficient retinal progenitor cells harbouring an intact p53 pathway, but not in the absence of p53. This synthetic lethality is mediated by the oncogenic miR-17-92 cluster because its deletion phenocopies Dicer1 loss in this context. miR-17-92 inactivation suppresses retinoblastoma formation in mice and co-silencing of miR-17/20a and p53 cooperatively decreases the viability of human retinoblastoma cells. These data provide an explanation for the selective pressure against loss of Dicer1 during tumorigenesis and a proof-of-concept that targeting miRNAs may potentially represent a general approach for synthetic lethal targeting of cancer cells that harbour specific cancer-inducing genotypes.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe