Genetic Engineering Publications - GEG Tech top picks

One of the biggest challenges facing cancer researchers is understanding why some patients do not respond to treatment. In some cases, tumours have what is known as multi-drug resistance (MDR), which severely limits treatment options for patients. However, researchers have discovered one of the causes of MDR and a potential strategy to combat it. In their study, the researchers began by using CRISPR technology in mouse stem cells to search for mutations that generate resistance to antitumor agents such as cisplatin, rigosertib or ultraviolet light. Mutations in the FBXW7 gene appeared early on, suggesting that this mutation could confer MDR. In addition, FBXW7-deficient cells showed an excess of mitochondrial proteins, which has already been shown to be associated with drug resistance. Nevertheless, a detailed analysis of these organelles further revealed that the mitochondria of these multi-drug resistant cells appeared to be under severe stress. Finally, the researchers showed that the antibiotic tigecycline is toxic to FBXW7-deficient cells because it activates the 'integrated stress response'. This study thus opens a new avenue of research to combat multidrug resistance.

The analysis of stem cell hierarchies in human cancers has been hampered by the impossibility of identifying or tracking tumor cell populations in an intact environment. To overcome this limitation, the scientists devised a strategy based on editing the genomes of patient‐derived tumor organoids using CRISPR/Cas9 technology to integrate reporter cassettes at desired marker genes. As proof of concept, they engineered human colorectal cancer (CRC) organoids that carry EGFP and lineage‐tracing cassettes knocked in the LGR5 locus.

The strategy described herein may have broad applications to study cell heterogeneity in human tumors.

Here, the scientists examined the piggyBac (PB) transposon as an alternative vehicle to deliver a guide RNA (gRNA) library for in vivo screening. Through hydrodynamic tail vein injections, they delivered a PB-CRISPR library into mouse liver. Rapid tumor formation could be observed in less than 2 mo. By sequencing analysis of PB-mediated gRNA insertions, they identified corresponding genes mediating tumorigenesis. Their results demonstrate that PB is a simple and nonviral choice for efficient in vivo delivery of CRISPR libraries for phenotype-driven screens.

In this review, the authors proposed that brain tumor modeling could be well established via CRISPR/Cas9 techniques. CRISPR/Cas9-mediated brain tumor modeling was likely to be more suitable for figuring out the pathogenesis of brain tumors, as CRISPR/Cas9 platform was a simple and more efficient biological toolbox for implementing mutagenesis of oncogenes or tumor suppressors that were closely linked with brain tumors.

In this study, the authors performed an unbiased CRISPR–Cas9 knockout screen on melanoma cells that were both resistant and addicted to inhibition of the serine/threonine-protein kinase BRAF, in order to functionally mine their genome for ‘addiction genes’.  Their results uncover a pathway that underpins drug addiction in cancer cells, which may help to guide the use of alternating therapeutic strategies for enhanced clinical responses in drug-resistant cancers.