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Red fluorescent dyes are usually charged, lipophilic molecules with relatively high molecular weight, which tend to localize in specific intracellular locations, e. g., a cyanine dye Cy5 is biased towards mitochondria. They are often used as markers of biomolecules including nucleic acids and proteins. Since the molecular weight of the dyes is much smaller than that of the biomolecules, the labelling has a negligible effect on the properties of the biomolecules. In contrast, conjugation of the dyes to low molecular weight (pro)drugs can dramatically alter their properties. For example, conjugates of Cy5 with lysosome‐targeting aminoferrocenes accumulate in mitochondria and exhibit no intracellular effects characteristic for the parent (pro)drugs. Herein we tested several neutral and negatively charged dyes for labelling lysosome‐targeting aminoferrocenes 7 and 8 as well as a non‐targeted control 3. We found that a BODIPY derivative BDP‐TR exhibits the desired unbiased properties: the conjugation does not disturb the intracellular localization of the (pro)drugs, their mode of action, and cancer cell specificity. We used the conjugates to clarify the mechanism of action of the aminoferrocenes. In particular, we identified new intermediates, explained why lysosome‐targeting aminoferrocenes are more potent than their non‐targeted counterparts, and evaluated their distribution in vivo. [ABSTRACT FROM AUTHOR]

Pro-drugs, which ideally release their active compound only at the site of action, i.e., in a cancer cell, are a promising approach towards an increased specificity and hence reduced side effects in chemotherapy. A popular form of pro-drugs is esters, which are activated upon their hydrolysis. Since carboxylesterases that catalyse such a hydrolysis reaction are also abundant in normal tissue, it is of great interest whether a putative pro-drug is a probable substrate of such an enzyme and hence bears the danger of being activated not just in the target environment, i.e., in cancer cells. In this work, we study the binding mode of carboxylesters of the drug molecule camptothecin, which is an inhibitor of topoisomerase I, of varying size to human carboxylesterase 2 (HCE2) by molecular docking and molecular dynamics simulations. A comparison to irinotecan, known to be a substrate of HCE2, shows that all three pro-drugs analysed in this work can bind to the HCE2 protein, but not in a pose that is well suited for subsequent hydrolysis. Our data suggest, moreover, that for the irinotecan substrate, a reactant-competent pose is stabilised once the initial proton transfer from the putative nucleophile Ser202 to the His431 of the catalytic triad has already occurred. Our simulation work also shows that it is important to go beyond the static models obtained from molecular docking and include the flexibility of enzyme–ligand complexes in solvents and at a finite temperature. Under such conditions, the pro-drugs studied in this work are unlikely to be hydrolysed by the HCE2 enzyme, indicating a low risk of undesired drug release in normal tissue. [ABSTRACT FROM AUTHOR]

As new generations of targeted therapies emerge and tumor genome sequencing discovers increasingly comprehensive mutation repertoires, the functional relationships of mutations to tumor phenotypes remain largely unknown. Here, we measured ex vivo sensitivity of 246 blood cancers to 63 drugs alongside genome, transcriptome, and DNA methylome analysis to understand determinants of drug response. We assembled a primary blood cancer cell encyclopedia data set that revealed disease-specific sensitivities for each cancer. Within chronic lymphocytic leukemia (CLL), responses to 62% of drugs were associated with 2 or more mutations, and linked the B cell receptor (BCR) pathway to trisomy 12, an important driver of CLL. Based on drug responses, the disease could be organized into phenotypic subgroups characterized by exploitable dependencies on BCR, mTOR, or MEK signaling and associated with mutations, gene expression, and DNA methylation. Fourteen percent of CLLs were driven by mTOR signaling in a non-BCR-dependent manner. Multivariate modeling revealed immunoglobulin heavy chain variable gene (IGHV) mutation status and trisomy 12 as the most important modulators of response to kinase inhibitors in CLL. Ex vivo drug responses were associated with outcome. This study overcomes the perception that most mutations do not influence drug response of cancer, and points to an updated approach to understanding tumor biology, with implications for biomarker discovery and cancer care., Introduction The clinical response to anticancer agents is heterogeneous, which is a major barrier to effective cancer care. Being able to more accurately predict response before choice of treatment would [...]

Despite their long history and their synthetic potential underlined by various recent advances, radical thiol‐yne coupling reactions have so far only rarely been exploited for the functionalization of biomolecules, and no examples yet exist for their application in live cells ‐ although natural thiols show widespread occurrence therein. By taking advantage of the particular cellular conditions of mitochondria in cancer cells, we have demonstrated that radical thiol‐yne coupling represents a powerful reaction principle for the selective targeting of these organelles. Within our studies, fluorescently labeled reactive alkyne probes were investigated, for which the fluorescent moiety was chosen to enable both mitochondria accumulation as well as highly sensitive detection. After preliminary studies under cell‐free conditions, the most promising alkyne‐dye conjugates were evaluated in various cellular experiments comprising analysis by flow cytometry and microscopy. All in all, these results pave the way for improved future therapeutic strategies relying on live‐cell compatibility and selectivity among cellular compartments. [ABSTRACT FROM AUTHOR]

A catalytic DNA-templated reaction of hydrolysis of an ester group in an N-modified peptide nucleic acid that is activated by a Cu(super 2+) complex-PNA is discovered and optimized. This reaction helps in developing a fully homogeneous and sensitive assay for sequence-specific DNA detection.