In VitroMembrane Penetration of Modified Peptide Nucleic Acid (PNA)

Abstract

Efficient cellular uptake is crucial for the success of any drug directed towards targets inside cells. Peptide nucleic acid (PNA), a DNA analog with a promising potential as a gene-directed drug, has been shown to display slow membrane penetration in cell cultures. We here used liposomes as an in vitro model of cell membranes to investigate the effect on penetration of a PNA molecule colvalently modified with a lipophilic group, an adamantyl moiety. The adamantyl attachment was found to increase the membrane-penetration rate of PNA three-fold, as compared to corresponding unmodified PNA. From the penetration behaviour of a number of small and large molecules we could conclude that passive diffusion is the mechanism for liposome-membrane passage. Flow linear dichroism (LD) of the modified PNA in presence of rod-shaped micelles, together with octanol-water distribution experiments, showed that the adamantyl-modified PNA is amphiphilic; the driving force behind the observed increased membrane-penetration rate appears to be an accumulation of the PNA in the lipid double layer.

Proteomic Analysis Identifies Oxidative Stress Induction by Adaphostin

“…5A). Results show marked similarity between treatments in that K562 cells were more resistant to each of the treatments than HL60 cells (IC 50 (Fig. 5B).…”

“…The IC 50 values determined for cell viability were 2.0, 1.5, and 1.5 Amol/L for HL60 cells and 10, 7, and 7 Amol/L for K562 cells for days 1, 2, and 3, respectively. In both assays, the Bcr/abl -negative cell line, HL60, was f5-to 10-fold more sensitive to adaphostin than the Bcr/abl -positive cell line, K562 (protein synthesis: IC 50 0.35 and 3.5 Amol/L; cell viability: IC 50 2.0 and 10 Amol/L, HL60 and K562, respectively). In the second set of assays, flow cytometry was used to monitor the induction of apoptosis using Annexin V/propidium iodide (Fig.…”

“…Attempts at transfecting the same construct into HL60 cells resulted in unacceptable levels of cell death (>50%). However, transfection of IGROV1 cells with the GSTP1 construct confirmed increased adaphostin resistance (data not shown) using both [ 14 C]leucine (IC 50 5.0 to 15 Amol/L) and WST assays (IC 50 15 to >30 Amol/L). Western blotting of a panel of cell lines using an anti-GSTP1 antibody was then done to determine whether a correlation exists between GSTP1 expression and adaphostin activity (Fig.…”

“…7A). The relative expression of each protein was then compared with the IC 50 values determined from protein synthesis inhibition assays. Catalase expression was constant throughout the panel, whereas myeloperoxidase was only detected in HL60 cells.…”

Semitelechelic HPMA Copolymers Functionalized with Triphenylphosphonium as Drug Carriers for Membrane Transduction and Mitochondrial Localization

“…These results can be compared to the coefficient for PNAs, which has been determined to be between 1 × 10 −2 and 2 × 10 −2 . 44 …”