Withdrawn: CircTDRD3 aggravates H/R-induced cardiomyocyte apoptosis via targeting miR-4295/TP63 axis.

The above article, published online on 5 December 2022, on Wiley Online Library (https://doi.org/10.1002/jbt.23003), has been withdrawn by agreement between the journal Editor in Chief, Hari Bhat, and Wiley Periodicals, LLC. The withdrawal has been agreed due to a technical error at the publisher that caused the article to be mistakenly published online although publication had been canceled because the authors did not approve their proof.

Tricking enzymes in living cells: a mechanism-based strategy for design of DNA topoisomerase biosensors.

Most activity-based molecular probes are designed to target enzymes that catalyze the breaking of chemical bonds and the conversion of a unimolecular substrate into bimolecular products. However, DNA topoisomerases are a class of enzymes that alter DNA topology without producing any molecular segments during catalysis, which hinders the development of practical methods for diagnosing these key biomarkers in living cells. Here, we established a new strategy for the effective sensing of the expression levels and catalytic activities of topoisomerases in cell-free systems and human cells. Using our newly designed biosensors, we tricked DNA topoisomerases within their catalytic cycles to switch on fluorescence and resume new rounds of catalysis. Considering that human topoisomerases have been widely recognized as biomarkers for multiple cancers and identified as promising targets for several anticancer drugs, we believe that these DNA-based biosensors and our design strategy would greatly benefit the future development of clinical tools for cancer diagnosis and treatment.

Cancer Biomarker-Triggered Disintegrable DNA Nanogels for Intelligent Drug Delivery.

Even though various techniques have been developed thus far for targeted delivery of therapeutics, design and fabrication of cancer biomarker-triggered disintegrable nanogels, which are exclusively composed of nucleic acid macromolecules, are still challenging nowadays. Here, we describe for the first time our creation of intelligent DNA nanogels whose backbones are sorely disintegrable by flap endonuclease 1 (FEN1), an enzymatic biomarker that is highly overexpressed in most cancer cells but not in their normal counterparts. It is the catalytic actions of intracellular FEN1 on bifurcated DNA structures that lead to the cancer-specific disintegration of our DNA nanogels and controlled release of drugs in target cancer cells. Consequently, the brand-new strategies introduced in the current report could break new ground in designing drug carriers for eliminating unwanted side effects of chemotherapeutic agents and live-cell probes for cancer risk assessment, diagnosis, and prognosis.

Graphene Quantum Dot-Based Nanocomposites for Diagnosing Cancer Biomarker APE1 in Living Cells.

As an essential DNA repair enzyme, apurinic/apyrimidinic endonuclease 1 (APE1) is overexpressed in most human cancers and is identified as a cancer diagnostic and predictive biomarker for cancer risk assessment, diagnosis, prognosis, and prediction of treatment efficacy. Despite its importance in cancer, however, it is still a significant challenge nowadays to sense abundance variation and monitor enzymatic activity of this biomarker in living cells. Here, we report our construction of biocompatible functional nanocomposites, which are a combination of meticulously designed unimolecular DNA and fine-sized graphene quantum dots. Upon utilization of these nanocomposites as diagnostic probes, massive accumulation of fluorescence signal in living cells can be triggered by merely a small amount of cellular APE1 through repeated cycles of enzymatic catalysis. Most critically, our delicate structural designs assure that these graphene quantum dot-based nanocomposites are capable of sensing cancer biomarker APE1 in identical type of cells under different cell conditions and can be applied to multiple cancerous cells in a highly sensitive and specific manners. This work not only brings about new methods for cytology-based cancer screening but also lays down a general principle for fabricating diagnostic probes that target other endogenous biomarkers in living cells.

DNA Binding and Cleavage Modes of Shishijimicin A.

Although shishijimicin A and its extreme potencies against an array of cancer cell lines have been known for more than a decade, its assumed DNA-cleaving mechanism has not been substantiated as yet. Herein we report studies that reveal binding and scission of double-stranded DNA by shishijimicin A. The results of these studies support the proposed hypothesis that DNA strand scissions are caused by 1,4-benzenoid diradicals formed by Bergman cycloaromatization of the enediyne core of shishijimicin A upon activation by thiols. In addition, double-stranded supercoiled DNA-cleavage experiments with shishijimicin A in competition with known minor groove binders, UV spectroscopic studies, and electrophoretic analysis were utilized to clarify the binding mode of the molecule to DNA. These investigations indicate that shishijimicin A binds to the minor groove of double-stranded DNA and that its ß-carboline moiety plays a role in the binding through intercalation. In addition, due to the fact that naked linker regions of DNA in the interphase and metaphase of eukaryotic cells are unprotected by histone proteins during entire cell cycles and because these unprotected regions of DNA are vulnerable to attack by DNA binders, it was concluded that the observed double-strand DNA cleavage and very low sequence selectivity by shishijimicin A may account for its extraordinary cytotoxicity.

Versatile Types of DNA-Based Nanobiosensors for Specific Detection of Cancer Biomarker FEN1 in Living Cells and Cell-Free Systems.

Flap structure-specific endonuclease 1 (FEN1) is overexpressed in various types of human cancer cells and has been recognized as a promising biomarker for cancer diagnosis in the recent years. In order to specifically detect the abundance and activity of this cancer-overexpressed enzyme, different types of DNA-based nanodevices were created during our investigations. It is shown in our studies that these newly designed biosensors are highly sensitive and specific for FEN1 in living cells as well as in cell-free systems. It is expected that these nanoprobes could be useful for monitoring FEN1 activity in human cancer cells, and also for cell-based screening of FEN1 inhibitors as new anticancer drugs.

Investigation of human flap structure-specific endonuclease 1 (FEN1) activity on primer-template models and exploration of a substrate-based FEN1 inhibitor.

Flap structure-specific endonuclease 1 (FEN1) is one of the enzymes that involve in Eukaryotic DNA replication and repair. Recent studies have proved that FEN1 is highly over-expressed in various types of cancer cells and is a drug target. However, a limited number of FEN1 inhibitors has been identified and approved. Herein, we investigate the catalytic activity of FEN1, and propose a substrate-based inhibitor. As a consequence, one of the phosphorothioate-modified substrates is proved to exhibit the most efficient inhibitory effect in our in vitro examinations. A novelly-designed substrate-based FEN1 inhibitor was accordingly constructed and determined a remarkable IC50 value.

Enrichment of omega-3 fatty acids in cod liver oil via alternate solvent winterization and enzymatic interesterification.

Enrichment of omega-3 fatty acids in cod liver oil via alternate operation of solvent winterization and enzymatic interesterification was attempted. Variables including separation method, solvent, oil concentration, time and temperature were optimized for the winterization. Meanwhile, Novozyme 435, Lipozyme RM IM and Lipozyme TL IM were screened for interesterification efficiency under different system air condition, time and temperature. In optimized method, alternate winterization (0.1g/mL oil/acetone, 24h, -80°C, precooled Büchner filtration) and interesterification (Lipozyme TL IM, N2 flow, 2.5h, 40°C) successfully doubled the omega-3 fatty acid content to 43.20 mol%. (1)H NMR was used to determine omega-3 fatty acid content, and GC-MS to characterize oil product, which mainly contained DHA (15.81 mol%) and EPA (20.23 mol%). The proposed method offers considerable efficiency and reduce production cost drastically. Oil produced thereof is with high quality and of particular importance for the development of omega-3 based active pharmaceutical ingredients.