CRISPR, the much-feted gene editing technology, has many uses outside of genetically altering organismal traits. Here's one.
CRISPR technology is an incredibly useful and versatile tool in health science, and has recently been used in a study to give insights into influences on cancer metastasis. Of all the technologies associated with modern genetics and genomics, CRISPR-Cas systems of gene editing are easily the most controversial, and likely the most publicly known. Most people with a passing interest in science, biological or otherwise, have probably heard the phrase CRISPR before. CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats (hence the acronym), and is a viral defence system native to bacteria which we have recently adopted to use to edit genes and genomes.
This is not the article in which I explain how CRISPR works and its notable features, though that is coming soon. This is the point where I’d like to start showing alternative uses of CRISPR than the popular notions of what CRISPR means for society. In our science fiction affected minds, gene editing means not only the eradication of genetic diseases and disorders, but the creation of a better class of human- people who are smarter, taller, more athletic, who live longer. Admittedly I haven’t done a great deal of research into how many people with the requisite expertise are seriously attempting such things (or even whether the requisite expertise to improve these things exists yet), but I’m fairly confident saying that most genetic scientists find this kind of hand-of-God style eugenics a dangerous and slippery slope to a more nefarious divisive type of genetic editing. Personally, the last thing I’d want to bring into society right now is another line we can use to divide people into in and out groups.
So, if that’s the popular idea of what CRISPR means for us as a species, how was CRISPR used in this study?
Scratchpad cells and family trees
Metastasis (plural metastases) occurs when cancerous cells leave the main origin tumour and enter other systems in the cancer patient’s body. It is a point at which the cancer becomes much, much more difficult to treat and is strongly associated with cancer remission. Hence, understanding how metastasis happens and whether there are ways of preventing it are integral to modern cancer research.
This study took mice with implanted human lung cancer and tracked the cancer cells to see how the cancer cells moved and eventually metastasised. This incredibly simple premise has a complication: as cancer cells replicate, with each cell generating its own lineage of offspring, how can we track single cells and their lineages? We can put a glowing protein in a cell of interest, but when that cell replicates, its offspring won’t have the glowing protein.
This is where CRISPR was uniquely helpful. CRISPR was used to create ‘scratchpad cells’, where each cell had its genome altered in a unique way by a CRISPR system. CRISPR created a small mutations in huge numbers of cancer cells, each mutation different and detectable, which was then passed on to each of the cells’ offspring. After metastasis was detected, it was possible to trace the metastatic cells’ origin to see if they developed from one cell from the original tumour or multiple.
Furthermore, it was found that when damage was done by CRISPR to one of the genes of the cancer cells, a gene called KRT17, metastasis occurred more frequently, suggesting the gene suppressed metastatic invasiveness.
Having an understanding of how cancers progress around the body, even in mice, is hugely helpful and scientists hope that this will lead to the ability to predict and even eventually kerb the metastasis of cancers before it takes place.
Conclusion
So that’s it- a reasonably simple* experiment using CRISPR as a genetic marker pen- marking cancer cells and their descendants to see where they go. It’s important to understand that CRISPR’s many uses extend beyond the obvious editing of the human genome, which is fraught with medical and ethical controversy, to experiments such as this one, where it is a simple solution to an otherwise complex problem. I hope this article gave you a new perspective on CRISPR as an experimental tool, and that you learned something new!
*simple to understand, maybe not so simple to perform
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