3 research outputs found
Flavones Inhibit the Activity of AKR1B10, a Promising Therapeutic Target for Cancer Treatment
AKR1B10 is an NADPH-dependent reductase
that plays an important
function in several physiological reactions such as the conversion
of retinal to retinol, reduction of isoprenyl aldehydes, and biotransformation
of procarcinogens and drugs. A growing body of evidence points to
the important role of the enzyme in the development of several types
of cancer (e.g., breast, hepatocellular), in which it is highly overexpressed.
AKR1B10 is regarded as a therapeutic target for the treatment of these
diseases, and potent and specific inhibitors may be promising therapeutic
agents. Several inhibitors of AKR1B10 have been described, but the
area of natural plant products has been investigated sparingly. In
the present study almost 40 diverse phenolic compounds and alkaloids
were examined for their ability to inhibit the recombinant AKR1B10
enzyme. The most potent inhibitorsapigenin, luteolin, and
7-hydroxyflavonewere further characterized in terms of IC<sub>50</sub>, selectivity, and mode of action. Molecular docking studies
were also conducted, which identified putative binding residues important
for the interaction. In addition, cellular studies demonstrated a
significant inhibition of the AKR1B10-mediated reduction of daunorubicin
in intact cells by these inhibitors without a considerable cytotoxic
effect. Although these compounds are moderately potent and selective
inhibitors of AKR1B10, they constitute a new structural type of AKR1B10
inhibitor and may serve as a template for the development of better
inhibitors
Catalytic Soman Scavenging by the Y337A/F338A Acetylcholinesterase Mutant Assisted with Novel Site-Directed Aldoximes
Exposure to the nerve agent soman
is difficult to treat due to
the rapid dealkylation of the soman-acetylcholinesterase (AChE) conjugate
known as aging. Oxime antidotes commonly used to reactivate organophosphate
inhibited AChE are ineffective against soman, while the efficacy of
the recommended nerve agent bioscavenger butyrylcholinesterase is
limited by strictly stoichiometric scavenging. To overcome this limitation,
we tested <i>ex vivo</i>, in human blood, and <i>in
vivo</i>, in soman exposed mice, the capacity of aging-resistant
human AChE mutant Y337A/F338A in combination with oxime HI-6 to act
as a catalytic bioscavenger of soman. HI-6 was previously shown <i>in vitro</i> to efficiently reactivate this mutant upon soman,
as well as VX, cyclosarin, sarin, and paraoxon, inhibition. We here
demonstrate that <i>ex vivo</i>, in whole human blood, 1
μM soman was detoxified within 30 min when supplemented with
0.5 μM Y337A/F338A AChE and 100 μM HI-6. This combination
was further tested <i>in vivo</i>. Catalytic scavenging
of soman in mice improved the therapeutic outcome and resulted in
the delayed onset of toxicity symptoms. Furthermore, in a preliminary <i>in vitro</i> screen we identified an even more efficacious oxime
than HI-6, in a series of 42 pyridinium aldoximes, and 5 imidazole
2-aldoxime <i>N</i>-propylpyridinium derivatives. One of
the later imidazole aldoximes, RS-170B, was a 2–3-fold more
effective reactivator of Y337A/F338A AChE than HI-6 due to the smaller
imidazole ring, as indicated by computational molecular models, that
affords a more productive angle of nucleophilic attack
Two-Step Mechanism of Cellular Uptake of Cationic Gold Nanoparticles Modified by (16-Mercaptohexadecyl)trimethylammonium Bromide
Cationic
colloidal gold nanorods (GNRs) have a great potential
as a theranostic tool for diverse medical applications. GNRs’
properties such as cellular internalization and stability are determined
by physicochemical characteristics of their surface coating. GNRs
modified by (16-mercaptohexadecyl)trimethylammonium bromide (MTAB), <sup>MTAB</sup>GNRs, show excellent cellular uptake. Despite their promise
for biomedicine, however, relatively little is known about the cellular
pathways that facilitate the uptake of GNRs, their subcellular fate
and intracellular persistence. Here we studied the mechanism of cellular
internalization and long-term fate of GNRs coated with MTAB, for which
the synthesis was optimized to give higher yield, in various human
cell types including normal diploid versus cancerous, and dividing
versus nondividing (senescent) cells. The process of <sup>MTAB</sup>GNRs internalization into their final destination in lysosomes proceeds
in two steps: (1) fast passive adhesion to cell membrane mediated
by sulfated proteoglycans occurring within minutes and (2) slower
active transmembrane and intracellular transport of individual nanorods
via clathrin-mediated endocytosis and of aggregated nanorods via macropinocytosis.
The expression of sulfated proteoglycans was the major factor determining
the extent of uptake by the respective cell types. Upon uptake into
proliferating cells, <sup>MTAB</sup>GNRs were diluted equally and
relatively rapidly into daughter cells; however, in nondividing/senescent
cells the loss of <sup>MTAB</sup>GNRs was gradual and very modest,
attributable mainly to exocytosis. Exocytosed <sup>MTAB</sup>GNRs
can again be internalized. These findings broaden our knowledge about
cellular uptake of gold nanorods, a crucial prerequisite for future
successful engineering of nanoparticles for biomedical applications
such as photothermal cancer therapy or elimination of senescent cells
as part of the emerging rejuvenation approach