Researchers have just discovered that a giant fungus first found 25 years ago in a forest on Michigan's Upper Peninsula has gotten much, much larger, and the secret to its phenomenal growth might hold the cure to cancer, reports Phys.org.

When it was first discovered, the mammoth mushroom, an Armillaria gallica specimen (also known as a honey mushroom), was estimated to weigh about 220,000 pounds, covering roughly 15 hectares. When it was recently reexamined, the fungus had ballooned to over 850,000 pounds spread across 70 hectares. Researchers also now believe the specimen is much older than previously estimated — 2,500 years old, to be exact.

"I view these estimates as the lower bound," explained James B. Anderson, a professor emeritus of biology at the University of Toronto Mississauga, who discovered the shroom. "The fungus could actually be much older. However, we think we have circumscribed its entire dimensions, which wasn't the case in 1992 [when it was first discovered.]"

A clue for cancer research?

Anderson was curious how this individual fungus could have survived so long, so he took samples to compare to a reference genome and to look at how its cell mutations accumulated over time. What he found was remarkable. The mutation rate was so low that even frequently occurring mutations "didn't have much of an impact on the fitness of the organism or on its appearance," he said. "What we think that tells us is that there must be some mechanism by which the fungus protects itself from mutations."

This adaptation is especially interesting because it could offer a counterpoint to cancer cell growth.

Although researchers are still studying how this fungus has avoided harmful mutations, they believe it might possess a mechanism whereby it localizes mutations to areas where they don't cause much damage. The next step will be to examine the DNA mechanisms at work inside this miraculous mushroom, to compare their stability to what happens inside cancer cells, which are highly unstable.

"It could be an interesting point of comparison," said Anderson. "Cancer is so unstable, mutates at a high rate and is prone to genomic changes, while A. gallica is a very persistent organism with few mutations."

A. gallica, like most fungi, produces mushrooms above the ground, but these growths on the surface are just a fraction of what's growing beneath. Much of the totality of the organism is composed of a network of underground tendrils called mycelium, which branch out looking for new food sources. This is how they can sometimes grow to such gargantuan sizes. In fact, the largest known fungus in the world, an Armillaria ostoyae found in Oregon, covers an area of about 925 acres.

First, they gave us antibiotics; it would be remarkable if fungi also gave us the cure to cancer. We'll just have to wait and see what researchers discover next.