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Insight from the Sea Urchin
How a spiky invertebrate helps unlock secrets of genes, reproduction, and cancer
One of the hallmarks of cancer is uncontrolled cell division. Researchers can learn more about how to treat cancer by studying urchin eggs like this one. The DNA in this cell has been damaged. This movie shows the cell trying to divide, but failing to do so because it can't replicate its DNA properly.

Knowing the why behind the how

Once again, solving one of the major mysteries in cell biology raised new questions. What makes cells divide in the first place? How do they know when to "rev up" for mitosis? Solving these mysteries would provide insight into a host of diseases-most notably cancer. And once again, the urchin provided answers.

As late as 1980, the secrets of what controlled cell division remained elusive. Preliminary experiments had pointed toward possible explanations, but it wasn't until 1982 that the real driver of cell division was spotted. That summer, researcher Tim Hunt was experimenting on fertilized urchin eggs, following the rate at which proteins were made in the cells. He noticed that the level of one particular protein built up until a cell began to divide. Then, during division, the protein disappeared, only to build up again until the next round. He dubbed this new protein cyclin and published a paper describing it as the controller of cell division.

At first, Hunt's ideas were met with skepticism, until research by other scientists showed not only that cyclin indeed played a key role in orchestrating cell division, but that similar proteins-cyclins-performed that same function in organisms from yeast cells to human beings. In 2001, Hunt, along with two other researchers who were also studying the cell cycle, received the Nobel Prize, giving the sea urchin some recognition for its hard work over the previous century.

Hold it Right There

It's no surprise that Hunt's work moved from cell cycle control to cancer research. Cancer is caused by a form of uncontrolled cell division, so understanding and regulating the cell cycle holds keys to cancer treatments. The urchin's contribution to our understanding of cancer began with Boveri, who noted abnormal division in cells with irregular chromosomes. Today, researchers employ urchins in the development of chemotherapy drugs that prevent mitosis by interfering with the formation of the mitotic apparatus of the replication of DNA. Again, the urchin is specially qualified: its eggs cells can be fertilized in a sea-water-like bath containing different drugs, and researchers can watch as the cells divide-or try to, but fail.

However, these drugs attack every dividing cell, not just tumor cells, which is why chemotherapy patients lose their hair and go through other physical challenges. Ideally, a drug would interfere with cell division only if there was a problem with DNA replication or regulation of the cycle. Fine-tuning new drugs to target only cancer cells is a key challenge in current cancer research.

Sea urchins in tidepool

Though the urchin has been contributing to biology for over a century, it remains on the cutting edge of research. In recent years, scientists have begun to use urchins to study gene regulatory networks, groups of genes that, working together, control the expression of traits. In fact, the urchin genome (which is relatively close to ours-another advantage of urchin-based research) has recently been sequenced. Urchins may one day help us understand the special properties of stem cells, the secrets to longevity, and how to prevent of skin cancer. So the next time you spot an urchin in an aquarium, or find its eggs glistening atop your sushi, stop a moment to thank this prickly invertebrate for all it's taught us.