from the debugging-the-debugging-of-wetware dept.
Editing cells' genomes with CRISPR-Cas9 might increase the risk that the altered cells, intended to treat disease, will trigger cancer, two studies published on Monday warn — a potential game-changer for the companies developing CRISPR-based therapies.
[...] The CEO of CRISPR Therapeutics, Sam Kulkarni, told STAT the results are "plausible." Although they likely apply to only one of the ways that CRISPR edits genomes (replacing disease-causing DNA with healthy versions) and not the other (just excising DNA), he said, "it's something we need to pay attention to, especially as CRISPR expands to more diseases. We need to do the work and make sure edited cells returned to patients don't become cancerous."
Another leading CRISPR scientist, who asked not to be named because of involvement with genome-editing companies, called the new data "pretty striking," and raised concerns that a potential fatal flaw in some uses of CRISPR had "been missed."
[...] "We found that cutting the genome with CRISPR-Cas9 induced the activation of ... p53[*]," said Emma Haapaniemi, the lead author of the Karolinska study. That "makes editing much more difficult."
The flip side of p53 repairing CRISPR edits, or killing cells that accept the edits, is that cells that survive with the edits do so precisely because they have a dysfunctional p53 and therefore lack this fix-it-or-kill-it mechanism.
I've been skeptical about this for awhile, and arguing this exact point: double stranded breaks would induce the majority of cells with the target sequence to self-destruct, lyse, or go senescent. I've seen this reflected in the data on cell counts of almost every paper that includes it. Things are much worse than I thought if "leading CRISPR scientists" are now acting surprised at this.
[*] Entry on Wikipedia for p53 states:
Tumor protein p53, also known as p53, cellular tumor antigen p53 (UniProt name), phosphoprotein p53, tumor suppressor p53, antigen NY-CO-13, or transformation-related protein 53 (TRP53), is any isoform of a protein encoded by homologous genes in various organisms, such as TP53 (humans) and Trp53 (mice). This homolog (originally thought to be, and often spoken of as, a single protein) is crucial in multicellular organisms, where it prevents cancer formation, thus, functions as a tumor suppressor. As such, p53 has been described as "the guardian of the genome" because of its role in conserving stability by preventing genome mutation. Hence TP53 is classified as a tumor suppressor gene. (Italics are used to denote the TP53 gene name and distinguish it from the protein it encodes.)