Patients with Huntington's disease, a fatal genetic illness that causes the breakdown of nerve cells in the brain, have up to 80 percent less cancer than the general population.

Scientists have discovered why Huntington's is so toxic to cancer cells and harnessed it for a novel approach to treat cancer, a new study reports.

Huntington's is caused by an over abundance of a certain type of repeating RNA sequences in one gene, huntingtin, present in every cell. The defect that causes the disease also is highly toxic to tumor cells. These repeating sequences -- in the form of so-called small interfering RNAs -- attack genes in the cell that are critical for survival. Nerve cells in the brain are vulnerable to this form of cell death, however, cancer cells appear to be much more susceptible.

"This molecule is a super assassin against all tumor cells," said senior author. "We've never seen anything this powerful." The study is published in the journal EMBO Reports.

To test the super assassin molecule in a treatment situation, researchers delivered the molecule in nanoparticles to mice with human ovarian cancer. The treatment significantly reduced the tumor growth with no toxicity to the mice, senior author said. Importantly, the tumors did not develop resistance to this form of cancer treatment.

Researchers are now refining the delivery method to increase its efficacy in reaching the tumor. The other challenge for the scientists is figuring out how to stabilize the nanoparticles, so they can be stored.

First author also used the molecule to treat human and mouse ovarian, breast, prostate, liver, brain, lung, skin and colon cancer cell lines. The molecule killed all cancer cells in both species.

In the case of people who have Huntington's, the gene huntingtin has too many repeating sequences of the triplet sequence CAG. The longer the repeating sequence, the earlier they will develop the disease.
"We believe a short-term treatment cancer therapy for a few weeks might be possible, where we could treat a patient to kill the cancer cells without causing the neurological issues that Huntington's patients suffer from," senior author said.

http://embor.embopress.org/content/early/2018/02/07/embr.201745336