Prostate cancer is notoriously resistant to immunotherapy — the tumors are “cold,” hiding from the immune system. Scientists have now found a way to switch them “hot,” at least in mice, using a CRISPR tool that edits RNA rather than DNA.
The molecular problem
Researchers at the University of Rochester and Duke, writing in Nature Biomedical Engineering, traced the resistance to a protein called SPSB1. In cancer cells, a shortened version of SPSB1's messenger RNA leads to excess SPSB1, which destroys MHC-1 — the surface flag T cells rely on to recognize a tumor. No flag, no immune attack.
The fix
Using CRISPR-Cas13 (which targets RNA), the team forced SPSB1's mRNA back to its normal length. That lowered SPSB1, restored MHC-1, and made the tumors visible to the immune system again.
“No one has ever done this before. It's an excellent preclinical model showing that mRNAs can be forced to re-lengthen,” said Eric J. Wagner, PhD, of the University of Rochester.
In mice, the approach dramatically improved the tumors' response to immune checkpoint therapy — with no detectable off-target CRISPR effects.
Why it matters
If it holds up, re-lengthening RNA could become a new lever for making immunotherapy work in cancers that currently shrug it off. But this is early, preclinical work in mice; RNA-editing therapies face real delivery and safety hurdles before any human use.