Development of Gene Editing Technology That Selectively Treats Cancer Cells

KAIST Research Team

Schematic diagram of gene editing technology that selectively targets disease cells to correct genes

[Asia Economy Reporter Kim Bong-su] Domestic researchers have developed a gene-editing system that selectively targets disease cells such as cancer cells for treatment through gene correction.

KAIST announced on the 14th that a research team led by Professor Lee Ji-min of the Graduate School of Medical Science and Engineering at KAIST, in collaboration with Senior Researcher Oh Seung-ja of the Korea Institute of Science and Technology (KIST) and Professor Lee Ju-yong of Kangwon National University, developed a gene-editing system (CRISPR/Cas9) capable of performing gene correction within the nucleus only in disease cells.

The research team designed a gene-editing system linked with a linker that can be specifically cleaved by microRNAs overexpressed in disease cells, utilizing the characteristic that intracellular microRNAs recognize and cleave specific sequences. This designed system remains in the cytoplasm without performing gene correction in normal cells with low levels of disease cell-specific microRNAs, but in disease cells, the linker is cleaved, allowing the gene-editing enzyme to enter the nucleus and perform gene correction.

This platform enables the gene-editing system to function only in disease cells, making it possible to conduct effective gene correction therapy even in actual patients where normal and disease cells are mixed.

MicroRNAs are RNA molecules 19 to 24 nucleotides (the basic units of DNA or RNA) in length that regulate genes post-transcriptionally. MicroRNAs bind to messenger RNAs transcribed from DNA through Argonaute (Ago) proteins and cleave the bound messenger RNAs. Abnormal expression of microRNAs has been reported in various diseases and is extensively studied as target biomarkers for disease treatment.

Although therapies targeting microRNAs are rapidly being researched for various diseases, challenges remain regarding delivery and dosage of therapeutic agents, cytotoxicity, and abnormal immune response activation.

The gene-editing system is a highly effective tool that performs precise gene correction by combining single guide RNA. However, there are technical limitations to its practical use. The biggest issue is stability, specifically off-target effects where genes other than the target gene are edited. Additionally, gene correction is difficult in environments where various cell types are mixed.

To address these issues, the research team devised an approach that utilizes the inherent ecology of disease cells. They created a gene-editing enzyme by attaching a nuclear export signal (NES) to the existing gene-editing enzyme (Cas9) with a nuclear localization signal (NLS), combined with the messenger RNA target sequence of disease cell microRNAs, naming this system the gene-editing 'Self Check-in.'

The team compared the gene correction function within human disease cells of gene-editing enzymes linked to the target sequence of microRNA-21, which is overexpressed in human disease cells, and microRNA-294, which is from experimental mice. They confirmed that only the gene-editing enzyme linked to the microRNA-21 target sequence is cleaved by intracellular microRNA-21, delivered to the nucleus, and able to perform its function.

The researchers demonstrated a positive correlation between the expression levels of microRNA-21 and the oncogenic protein Ezh2 in various lung cancer cells, and successfully performed gene correction of the oncogene Ezh2 in lung cancer cells overexpressing microRNA-21 using the 'Self Check-in' system.

Furthermore, cancer cells acquire drug resistance when continuously exposed to anticancer drugs. The team confirmed that the expression of microRNA-21 and Ezh2 in lung cancer cells actually increases upon administration of the anticancer drug cisplatin. Through mouse experiments, they showed that combining Ezh2 gene correction using the gene-editing Self Check-in technology with cisplatin treatment more effectively suppresses the growth of lung cancer cells.

The gene-editing Self Check-in technology developed by the research team functions only in disease cells, minimizing off-target effects and offering high stability by utilizing an intracellular system. Additionally, since the single guide RNA and messenger RNA target sequences can be replaced according to the situation, it is expected to be applicable to various diseases.

The research team stated, "The gene-editing Self Check-in technology improves the problems of existing gene-editing systems, confirming that it can specifically correct genes in disease cells with high specificity," and added, "The technology can be applied to various disease-associated microRNAs."

The research results were published online on the 30th of last month in the international journal Nucleic Acids Research (IF 16.971). The paper is titled 'Cytosolic microRNA-inducible nuclear translocation of Cas9 protein for disease-specific genome modification.'

This content was produced with the assistance of AI translation services.