June 13, 2009
MicroRNA Stops Liver Cancer In Mice

This treatment is roughly analogous to a security patch to an operating system.

A new study suggests that delivering small RNAs, known as microRNAs, to cancer cells could help to stop the disease in its tracks. microRNAs control gene expression and are commonly lost in cancerous tumors. Researchers have shown that replacement of a single microRNA in mice with an extremely aggressive form of liver cancer can be enough to halt their disease, according to a report in the June 12 issue of the journal Cell, a Cell Press publication.

Cancer amounts of cells that have damaged programs. Their information state is incorrect. MicroRNAs work naturally in cells to regulate gene expression. Using microRNAs to change how the genetic program of a cell executes amounts to attacking cancer on the level where it goes wrong in the first place. This is how I expect cancer will eventually be cured.

The microRNA was packed into viruses and those viruses carried the microRNA into cells. That can be problematic for a few reasons including immune attacks against viruses. But the viruses worked well in this instance..

They delivered the microRNA to the mice using a virus that has been applied in other forms of gene therapy. That so-called adeno-associated virus (AAV) is particularly good at targeting new genetic material to the liver.

"Mice given the control virus showed no change in the growth rate of their tumors and within three weeks, the cancer had taken over," said Joshua Mendell of Johns Hopkins University School of Medicine. "When we gave them the microRNA-carrying virus, some animals showed essentially complete regression of their tumors." In other cases, he said, the tumors were much smaller and far fewer.

Mendell said his team, which included his father Jerry Mendell at The Research Institute at Nationwide Children's Hospital, was hopeful the strategy would work based on previous evidence. Nonetheless, he added, "it is always surprising to see results this striking."

One problem with curing cancer is that large numbers of of cells are usually involved by the time of diagnosis. Viruses would need to enter just about every cancer cell in order to totally eradicate the cancer. I'm therefore surprised this treatment worked as well as it did.

The microRNA was highly selective in only changing cancer cells.

They were also amazed by how specifically the microRNA affected cancer cells, while leaving normal cells unscathed. "We found that the tumor cells are exquisitely sensitive [to microRNA replacement]--they not only stopped proliferating, but they actually died," he said. Meanwhile, the mice showed no evidence of any damage to their normal liver tissue.

Cancer is a major problem for those of us who want to reverse aging with rejuvenation therapies. Even young people die from cancer. Youthfulness is not a guaranteed protector against cancer. Rejuvenation by itself is not enough to protect us against cancer. We also need the ability to wipe out cancer cells and do so with little collateral damage. Therapies based on microRNAs might provide us with this capability.

Also see here and here for more details on this study.

Share |      Randall Parker, 2009 June 13 11:04 PM  Biotech Cancer

Fly said at June 14, 2009 1:10 PM:

"Viruses would need to enter just about every cancer cell in order to totally eradicate the cancer."

A virus infected cancer cell might produce large amounts of the microRNA. Some of that microRNA should be exported and taken up by neighboring cells. So infecting a fraction of the cancer cells might suffice. (Membrane tunnels that can form between cells and support transport of large molecules between cells may also play a role. http://en.wikipedia.org/wiki/Membrane_nanotube )

It should also be possible to use nanocapsules to carry the microRNA. Surface molecules embedded in the nanocapsule would target the cancer cell. It should be easy to manufacture large quantities of the microRNA carrying nanocapsules.

I don't think it is necessary to totally eradicate the cancer. You just have to keep the total number of cancer cells small. Evolving resistance requires millions of growing cells. Also a large cancer mass may make it easier for a new metastatic cancer to grow. The large cancer releases factors into the blood system that then affect the cellular environment at the new cancer site, e.g., angiogenesis, immune response, and tissue repair. So reducing the large cancer mass can help the body fight new metastatic sites.

Timothy said at June 16, 2009 9:47 PM:

When do they expect to have human trials???


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