Infection of the macrophage cell line NR8383 with Mycobacterium tuberculosis (H37Ra) leads to an increase in oligodeoxynucleotide accumulation

Characterizing Oligonucleotide Uptake in Cultured Cells: A Case Study Using AS1411 Aptamer

Oligonucleotides can be designed or evolved to bind to specific DNA, RNA, protein, or small molecule targets and thereby alter the biological function of the target. The therapeutic potential of oligonucleotides targeted to intracellular molecules will depend largely on their ability to be taken up by the cells of interest, as well as their subsequent subcellular distribution. Here we describe methods to characterize the extent and mechanism of cellular uptake of AS1411, an aptamer oligonucleotide that has progressed to human clinical trials and which is also widely used by researchers as a cancer-targeting ligand.

Primary Lung Dendritic Cell Cultures to Assess Efficacy of Spectinamide-1599 Against Intracellular Mycobacterium tuberculosis

There is an urgent need to treat tuberculosis (TB) quickly, effectively and without side effects. Mycobacterium tuberculosis (Mtb), the causative organism of TB, can survive for long periods of time within macrophages and dendritic cells and these intracellular bacilli are difficult to eliminate with current drug regimens. It is well established that Mtb responds differentially to drug treatment depending on its extracellular and intracellular location and replicative state. In this study, we isolated and cultured lung derived dendritic cells to be used as a screening system for drug efficacy against intracellular mycobacteria. Using mono- or combination drug treatments, we studied the action of spectinamide-1599 and pyrazinamide (antibiotics targeting slow-growing bacilli) in killing bacilli located within lung derived dendritic cells. Furthermore, because IFN-γ is an essential cytokine produced in response to Mtb infection and present during TB chemotherapy, we also assessed the efficacy of these drugs in the presence and absence of IFN-γ. Our results demonstrated that monotherapy with either spectinamide-1599 or pyrazinamide can reduce the intracellular bacterial burden by more than 99.9%. Even more impressive is that when TB infected lung derived dendritic cells are treated with spectinamide-1599 and pyrazinamide in combination with IFN-γ a strong synergistic effect was observed, which reduced the intracellular burden below the limit of detection. We concluded that IFN-γ activation of lung derived dendritic cells is essential for synergy between spectinamide-1599 and pyrazinamide.

Inhibition of human carcinoma and neuroblastoma cell proliferation by anti-c-myc siRNA

Suppression of c-myc proto-oncogene expression by small interfering RNA (siRNA) in human epidermoid carcinoma KB-3-1 and neuroblastoma SK-N-MC cell lines was investigated. The siRNA duplex targeted to the exon 3 of c-myc mRNA (siRNA-I) was prepared by in vitro transcription using T7 RNA polymerase and short double-stranded DNA (dsDNA) templates. siRNA-I was shown to efficiently decrease c-myc mRNA expression in both tumor cell lines and to arrest their proliferation. Incubation of KB-3-1 cells with 150 nM siRNA-I results in a 92% decrease in the c-myc mRNA level and an 83% decrease in the protein level. In SK-N-MC cells, 150 nM siRNA-I causes a 60% decrease in the c-myc mRNA level and a 55% decrease in the protein level. The reduction of the c-myc mRNA level correlates with the inhibition of cell proliferation; 150 nM siRNA-I causes a 2.5-fold reduction in the SK-N-MC proliferation rate and a 15-fold decrease in the proliferation rate and complete arrest of cell division in KB-3-1 cells. siRNA-I has little effect on proliferation of the IMR-32 cells that overexpress the N-myc but not the c-myc gene, demonstrating that siRNA-I antiproliferation activity is mediated by specific block of c-myc expression.

Infection by Mycoplasma hyorhinis strongly enhances uptake of antisense oligonucleotides: a reassessment of receptor-mediated endocytosis in the HepG2 cell line

This paper shows that the approximately 66 kDa band, previously isolated from the HepG2 cell line as an oligonucleotide (ON) plasma membrane 'receptor', is induced by Mycoplasma infection. Moreover, this band has been identified as the invariant membrane protein of Mycoplasma hyorhinis, p70, based on ribosomal DNA sequencing combined with ON ligand blotting after p70 immunoprecipitation by a monoclonal antibody. Whereas antibiotic treatment of infected HepG2 cells strongly decreased ON capture, as measured by a biochemical assay, conversely, deliberate infection of HeLa cells with M.hyorhinis dramatically promoted ON uptake but did not affect receptor-mediated endocytosis of transferrin. This was confirmed by confocal microscopy of infected HepG2 cells, which also showed an indistinguishable labelling pattern after exposure of living cells to fluorescent ON and after p70 immunolabelling in permeabilised fixed cells. We propose that ON binds to p70 on M.hyorhinis attached at the cell surface, after which the complex is internalised by 'piggy-back' endocytosis.