Discovery of the antitumor effects of a porphyrazine diol (Pz 285) in MDA-MB-231 breast tumor xenograft models in mice

A series of porphyrazines (Pzs) with chiral bis-acetal moieties in the β-pyrrole positions ((2R,3R)-2,3-dimethyl-2,3-dimethoxy-1,4-diox-2-ene) have been synthesized and screened as antitumor agents in MDA-MB-231 breast tumor cellsin vitro. The leadPz 285was further tested in a mouse tumor xenograft model with Td-tomato-luc2 fluorescent breast tumor cells (MDA-MB-231 LM24 Her2+) that are highly metastatic to the lungs.Pz 285shows marked antitumor effectsin vivo, with treated mice exhibiting longer median survival that we attribute to smaller primary tumor regrowth after resection and less occurrence of metastasis when compared to vehicle control groups.Pz 285is further compared to the clinically approved chemotherapeutic doxorubicin (Dox). This report lays the groundwork for development of an understudied class of compounds for classical chemotherapy

A predictive model for the selective accumulation of chemicals in tumor cells

Cationic lipophilic dyes can accumulate in mitochondria, and especially in mitochondria of tumor cells. We investigated the chemical properties and the processes allowing selective uptake into tumor cells using the Fick–Nernst–Planck equation. The model simulates uptake into cytoplasm and mitochondria and is valid for neutral molecules and ions, and thus also for weak electrolytes. The differential equation system was analytically solved for the steady-state and the dynamic case. The parameterization was for a generic human cell, with a 60 mV more negative potential at the inner mitochondrial membrane of generic tumor cells. The chemical input data were the lipophilicity (logKOW), the acid/base dissociation constant (pKa) and the electric charge (z). Accumulation in mitochondria occurred for polar acids with pKa between 5 and 9 owing to the ion trap, and for lipophilic bases with pKa>11 or permanent cations owing to electrical attraction. Selective accumulation in tumor cells was found for monovalent cations or strong bases with logKOW of the cation between −2 and 2, with the optimum near 0. The results are in agreement with experimental results for rhodamine 123, a series of cationic triarylmethane dyes, F16 and MKT-077, an anticancer drug targeting tumor mitochondria

Inducing fluorescence of uranyl acetate as a dual-purpose contrast agent for correlative light-electron microscopy with nanometre precision

Abstract Correlative light-electron microscopy (CLEM) combines the high spatial resolution of transmission electron microscopy (TEM) with the capability of fluorescence light microscopy (FLM) to locate rare or transient cellular events within a large field of view. CLEM is therefore a powerful technique to study cellular processes. Aligning images derived from both imaging modalities is a prerequisite to correlate the two microscopy data sets, and poor alignment can limit interpretability of the data. Here, we describe how uranyl acetate, a commonly-used contrast agent for TEM, can be induced to fluoresce brightly at cryogenic temperatures (−195 °C) and imaged by cryoFLM using standard filter sets. This dual-purpose contrast agent can be used as a general tool for CLEM, whereby the equivalent staining allows direct correlation between fluorescence and TEM images. We demonstrate the potential of this approach by performing multi-colour CLEM of cells containing equine arteritis virus proteins tagged with either green- or red-fluorescent protein, and achieve high-precision localization of virus-induced intracellular membrane modifications. Using uranyl acetate as a dual-purpose contrast agent, we achieve an image alignment precision of ~30 nm, twice as accurate as when using fiducial beads, which will be essential for combining TEM with the evolving field of super-resolution light microscopy