Deer Grow Antlers and Fight Cancer

Did you ever wonder how Rudolph grows new antlers so fast—and regenerates them? To say nothing of pronghorns, muntjacs, gazelles and buffaloes? The only completely regenerable organ found in mammals. And they don’t get cancer.

So what can we learn here about bone regeneration and fighting cancer?

A large group of scientists, mostly in China, are trying to find out. They are mining the Ruminant Genome Project.
First they did what’s become the obvious for everything:
• Map all the genomes. Sequence every cervid’s DNA and make a giant family tree.
• Find candidate genes. That is, which genes that act on development show consistent dependence on regenerable headgear? And maybe don’t appear in non-antlered cousins.
• Map transcriptomes. That is, the pattern of RNA transcripts actually copied from the DNA genomes during antler regeneration. Our technology now converts the RNA copies back into DNA, which gets sequenced on Illumina super-sequencing machines. The transcriptome tells us which genes of an organisms’ genome are actually getting used in certain tissues.
The phylogeny above shows how the relationships came out. Notice that two groups were included that had lost antlers through reductive evolution, the Moschidae and the Chinese water deer. This makes sense as a control—genes specific to antler growth should be absent or down-regulated in the bare-headed species.

So what molecular results came out? Some fascinating clues.
• Horns or antlers expressed regulators of development in the neural crest, the earliest embryonic region of cells giving rise to bones and muscle as well as nerves.
• Amazingly, the genes expressed during antler growth have more in common with osteosarcoma (bone cancer) than with normal mammalian bone. In other words, deer use the same molecular tools of cancer to rapidly grow their antlers. Yet deer have less cancer than other animals. How do they regulate antler bone growth so tightly?
• Antlers are full of nerve fibers. The “nerve growth factor receptor” is highly expressed in growing antlers.

So have we cured cancer yet? A bit early for that, although the scientists assure us that “a lot of genes that exist in cows and goats and deer and sheep also exist in humans.” In other words, just maybe if you can’t yet regrow your hair, you might grow a prong or two. 😉