CRISPR/Cas9-Mediated Genome Editing of Epigenetic Factors for Cancer Therapy

Abstract

Advances in engineered recombinant nuclease have provided facile and reliable methods for genome editing. Especially with the development of the CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 (CRISPR-associated protein-9 nuclease) system, the discovery of various versions of Cas9 proteins and delivery carriers, it is now practicable to introduce desired mutations into the genome, to correct disease-related mutations, and to activate or suppress genes of interest. Epigenetic regulators are often disturbed in cancer cells and are essential for the transformation of normal to cancerous cells. Tumor-related epigenetic alterations or epigenetic factor mutations play a major part during the various steps of carcinogenesis and affect a variety of cancer-related genes and a wide range of cancerous phenotypes. Therefore, epigenetic regulatory enzymes might be candidate targets for cancer therapy. In this review, we discuss prospects of CRISPR/Cas9-based genome editing in targeting epigenetics for cancer gene therapy.

CRISPR genome editing and its medical applications

“…The natural CRISPR/Cas9 system in bacteria has two key RNA components, mature crRNA and tracrRNA. These two RNAs share partial sequence complementarity and form a two-RNA structure that directs Cas9 to target invading viral or plasmid DNA [2,4,21]. In the natural system of crRNA, CRISPR is a fixed area between various parts of the virus genome integrated into the genome of bacteria.…”

“…Today, the CRISPR system has wide potential for applications in the field of cancer, including epigenetic cancer therapy [4], turning the genes involved in cancer development on and off, modelling cancer, examining the protein domains involved in cancer to evaluate the drug targets, reviewing and modelling the cancers in which several genes are involved or cancers that are caused by chromosomal clutter and rearrangements, and identifying the genes involved in cancer development [3,[43][44][45]. According to various genetic and epigenetic factors in cancer development, cancer modelling using the CRISPR system is expected play an important role in the detection and the identification of factors involved in cancer.…”

“…Using the CRISPR system, the desired genes can be turned on and off. CRISPR will create mutations in enzymes associated with epigenetic regulation [4].…”

“…Initially, two methods of zinc-finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs) were used for this purpose [1]. These methods had limitations due to high costs, the difficulty of endonucleases system design, and the low performance of precise cutting [2][3][4][5].…”

CRISPR/Cas9 therapeutics: a cure for cancer and other genetic diseases

“…The nuclease genome editing technologies effectively and efficiently alter genome sequences, hence providing an opportunity to correct disease causing mutations, but requires potent delivery methods to cells. The Cas9 can be delivered to cells as mRNA, however the mRNA is unstable and is not suitable for long term gene therapy purposes, however the alterations to genome remains and widely used in model organisms including mouse, zebrafish, Drosophila and C. elegans [46, 47]. The expression of Cas9 and gRNA complex in cultured mammalian cells is mostly done physically by delivering non-replicating plasmids expressing these cassettes.…”