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[5] [6] These molecules can be composed of single-stranded DNA or RNA and are generally 13–25 nucleotides long. [6] [7] The antisense oligonucleotides can affect gene expression in two ways: by using an RNase H-dependent mechanism or by using a steric blocking mechanism.
Classic DNA inhibitors such as the quinolones act upon DNA gyrase as a topoisomerase inhibitor. [2] Another group of DNA inhibitors, including nitrofurantoin and metronidazole, act upon anaerobic bacteria. [3] These act by generating metabolites that are incorporated into DNA strands, which then are more prone to breakage. [4] These drugs are ...
A hypomethylating agent (or demethylating agent [1]) is a drug that inhibits DNA methylation: the modification of DNA nucleotides by addition of a methyl group.Because DNA methylation affects cellular function through successive generations of cells without changing the underlying DNA sequence, treatment with a hypomethylating agent is considered a type of epigenetic therapy.
To carry out gene expression, a cell must control the coiling and uncoiling of DNA around histones.This is accomplished with the assistance of histone acetyl transferases (HAT), which acetylate the lysine residues in core histones leading to a less compact and more transcriptionally active euchromatin, and, on the converse, the actions of histone deacetylases (HDAC), which remove the acetyl ...
Azacitidine is a chemical analogue of the nucleoside cytidine, which is present in DNA and RNA.It is thought to have antineoplastic activity via two mechanisms – at low doses, by inhibiting of DNA methyltransferase, causing hypomethylation of DNA, [16] and at high doses, by its direct cytotoxicity to abnormal hematopoietic cells in the bone marrow through its incorporation into DNA and RNA ...
Drug resistance can emerge as a result of continued and repetitive usage of a drug, giving pathogens time to develop defenses against drugs designed to kill them. [20] In cancer, overexpression, for instance in DNA methylation and histone deactylase, can cause deleterious effects which can enhance drug resistance behaviors such as drug efflux ...
Lomustine also has other biologic effects including inhibition of DNA synthesis and some cell phase specificity. In general, nitrosureas lack cross-resistance with other alkylating agents. Since lomustine is a nitrosurea, it inhibits several processes such as carbomylation and the modification of cellular proteins. [ 18 ]
Dialkylating agents can react with two different 7-N-guanine residues, and, if these are in different strands of DNA, the result is cross-linkage of the DNA strands, which prevents uncoiling of the DNA double helix. If the two guanine residues are in the same strand, the result is called limpet attachment of the drug molecule to the DNA.