Biology subjects

Kitowski, A.

Publications and source records attributed to Kitowski, A..

4 recordsLinked to original sources

bioRxiv2025

The delivery of nano-formulated drugs to solid tumours is selectively increased by co-application of the vascular disrupting agent CA4P

Improving the efficacy of existing cytotoxic chemotherapeutics requires increasing drug delivery to tumours while minimising systemic toxicity. Formulating these drugs as nanoparticles can reduce their exposure to healthy tissues, but broadly applicable strategies to enhance tumoral accumulation are lacking. Here, we show that co-administering small molecule vascular disrupting agents together with nanoparticle formulations (e.g. diagnostic reporters, or clinical drugs irinotecan and doxorubicin) increases their tumoral uptake by up to threefold, without raising systemic exposure. In a syngeneic mouse model of triple-negative breast cancer, this enhancement diminished when co-treatments were repeated, limiting its therapeutic benefit. However, since most solid tumour types are susceptible to vascular disrupting agents, this approach may be a broadly applicable strategy to improve the selectivity of drug delivery: with particular relevance for single dose use in diagnostic or research settings. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=101 SRC="FIGDIR/small/669501v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@a5b07corg.highwire.dtl.DTLVardef@1e5dcd2org.highwire.dtl.DTLVardef@49134org.highwire.dtl.DTLVardef@1d90aae_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2025

Cellularly-Retained Fluorogenic Probes for Sensitive Cell-Resolved Bioactivity Imaging

Here, we develop a general design for high-quality fluorogenic activity probes to quantify biological processes in live cells, by creating a scaffold that efficiently generates cell-retained bright fluorescent soluble products upon reaction with biochemical targets. Live cell probes must be designed to be membrane-permeable; but that often means that their fluorophore products are similarly permeable, resulting in rapid signal loss from the activating cell: which limits their cell-by-cell resolution as well as their sensitivity for quantifying low-turnover processes. Current strategies to retain fluorescent products within cells usually disrupt native biology: e.g. by non-specific alkylation or solid precipitation. Here, scanning charge- and polarity-based approaches to trigger cell retention, we developed a bright fluorogenic rhodol scaffold Trappable Green (TraG) that balances all key requirements for signal integration (rapid probe entry, but effective product retention, across a variety of cell lines) and is easily adaptable to quantify many target types (shown here with probes for GSH, TrxR, and H2O2). The simple and rugged TraG scaffold can now permit straightforward elaboration to a range of cell-retained enzyme activity probes, that enable more accurate cell-resolved imaging as well as higher-sensitivity integration of low-turnover processes, without the drawbacks of alkylation or precipitation-based strategies. O_FIG O_LINKSMALLFIG WIDTH=176 HEIGHT=200 SRC="FIGDIR/small/649302v1_ufig1.gif" ALT="Figure 1"> View larger version (49K): org.highwire.dtl.DTLVardef@1d5a99forg.highwire.dtl.DTLVardef@730dd8org.highwire.dtl.DTLVardef@191ea65org.highwire.dtl.DTLVardef@b393d8_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2023

Imaging membrane damage in ferroptosis and necrosis by wash-free fluorogenic chemical probes

Selectively labelling cells with damaged membranes is needed in contexts as simple as identifying dead cells in culture, or as complex as imaging membrane barrier functionality in vivo. The commonly used dyes are permanently coloured/fluorescent dyes that are simply excluded by intact membranes, but to achieve good image contrast therefore requires removing their extracellular signal by washing or background subtraction, which are not possible in vivo. Here, we develop fluorogenic probes which sensitively and selectively reveal damaged cells, without needing washing steps since their fluorescence turns on from near-zero background. From a set of novel fluorogenic probes impermeabilised by sulfonations along different vectors, we identify a specific disulfonated fluorogenic scaffold that enters cells only upon membrane damage, where it is enzymatically activated to mark them. The esterase probe iPS-FS2 is a reliable tool to reveal live cells that have been permeabilised by biological, biochemical, or physical membrane damage; and it can be used in multicolour microscopy. We confirm the modularity of this approach by also adapting it for redox-unmasked cell-excluded probes with improved hydrolytic stability. This scaffold-based design thus provides tools for wash-free in vivo imaging of membrane damage, which is relevant across many pathologies. The insightss gained from these probes should also be translatable to damage-targeted prodrugs, for selective therapy of membrane-compromised cells. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=145 SRC="FIGDIR/small/543437v1_ufig1.gif" ALT="Figure 1"> View larger version (53K): org.highwire.dtl.DTLVardef@1594016org.highwire.dtl.DTLVardef@7e7053org.highwire.dtl.DTLVardef@1008cb0org.highwire.dtl.DTLVardef@1148bd7_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2022

Cyclic dichalcogenides extend the reach of bioreductive prodrugs to harness the thioredoxin system: applications to seco-duocarmycins

Small molecule prodrug approaches that can activate cancer therapeutics selectively in tumors are urgently needed. Here, we developed the first antitumor prodrugs designed for activation by the thioredoxin (Trx) oxidoreductase system. This critical cellular disulfide redox axis is tightly linked to dysregulated redox/metabolic states in cancer, yet it cannot be addressed by current bioreductive prodrugs, which mainly cluster around oxidised nitrogen species. We instead harnessed Trx/TrxR-specific artificial dichalcogenides to gate the bioactivity of a series of 10 "off-to-on" reduction-activated duocarmycin prodrugs. The prodrugs were tested for cell-free and cellular activity dependent on reducing enzyme systems in 177 cell lines, to establish broad trends for redox-based cellular bioactivity of the dichalcogenides. They were well tolerated in vivo in mice, indicating low systemic release of their duocarmycin cargo, and in vivo anti-tumor efficacy trials in mouse models of breast and pancreatic cancer gave promising initial results indicating effective tumoral drug release, presumably by in situ bioreductive activation. This work therefore presents a chemically novel class of bioreductive prodrugs against a previously unaddressed reductase type, validates its ability to access in vivo compatible small-molecule prodrugs even of potently cumulative toxins, and so introduces carefully tuned dichalcogenides as a platform strategy for specific bioreduction-based release.

biochemistry↗