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Space Experiment Provides Insights for Developing Cancer Drugs

Cancer,ISS,Micro Gravity
Kat Friedrich
Burton Booz
April 2, 202410:00 AM UTC (UTC +0)

The quest for a cure for pancreatic, lung, and colon cancer has led to space.

Researchers from the Frederick National Laboratory sent several cancer-causing, mutant KRAS proteins to the International Space Station to crystallize in December 2018. The samples orbited in space for five weeks, and were then photographed in a laboratory using X-rays after they splashed down into the Pacific Ocean.

The research resulted in progress being made toward a goal of developing a drug that can "lock" the KRAS proteins' tails, effectively preventing cancers from growing. This could potentially help many cancer patients.

“This was a very exciting opportunity,” said Albert Chan, a scientist at FNL. “Before I signed up for it, I had heard of crystallizing proteins in space on the International Space Station, but actually being involved in it was an amazing experience. I learned a lot. I learned how to not take things for granted. I had to analyze everything."

There's a long history to this area of research. According to the National Aeronautics and Space Administration, as of 2021, university researchers and drug companies had engaged in over 500 experiments on the ISS that involved growing protein crystals, over a period of 20 years.

What role do proteins play in the human body?

And why are they important for researchers to study?

According to the U.S. government website Medline Plus, “Proteins are large, complex molecules that play many critical roles in the body. They do most of the work in cells and are required for the structure, function and regulation of the body’s tissues and organs."

Scientists generally agree that there are close to 20,000 proteins in the human body, according to an article by Nathan Ahlgren, assistant professor of biology at Clark University.

Launches carrying sensitive research are exciting (and stressful) times for the teams involved in this type of research. In a blog post for the National Cancer Institute, Chan described the Dec. 5 Falcon 9 rocket launch carrying the experimental equipment as “a flash of fire, followed by an unrelenting rumbling sound that crescendos to a deafening roar, shaking the ground and the air.” The launch was part of SpaceX CRS-16, a commercial resupply mission on a Dragon spacecraft departing from Cape Canaveral, Florida.

The experimental equipment onboard needed to withstand both cold temperatures — since the samples were sent up to space frozen — and also the intense vibration from re-entry and a violent splash-down in the Pacific Ocean. 

“The [crystallization research] steps are actually quite similar to what we would do under normal Earth gravity,” Chan said. But instead of mixing the proteins and the crystallization solutions together on Earth and waiting for crystals to appear, the team froze the samples immediately after mixing them, packaged them in dry ice, and sent them to Florida.

In Florida, staff loaded them into the capsule and sent them up to the ISS, Chan said. On Dec. 9, Alexander Gerst, an astronaut from the European Space Agency, unpacked the samples so they could defrost and the proteins could crystallize in a microgravity environment.

The samples were then ejected from the ISS, after which they splashed down in the Pacific Ocean near the California coast. Chan took a commercial plane to retrieve them. He brought the samples on a plane to Argonne National Laboratory, where they were photographed using an X-ray technique.

“They have a facility called a synchrotron,” Chan said. “It is a very strong X-ray source. So it shoots the X-ray to the protein crystals. And from there we can get a diffraction pattern that we convert back into a 3D model of the protein.”

Chan and his coworker Dhirendra Simanshu, a principal scientist at FNL, compared the results to a similar experiment conducted at FNL. 

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Why was this experiment conducted in microgravity?

“Protein crystal growth (PCG) is a major area of cancer-related study in microgravity,” NASA says. “A detailed look at the early decades of cancer research in space highlighted the benefits of microgravity: cells grow into 3D forms that behave much as they do in the body, cell growth and function such as gene expression and cell signaling are different, and cell cultures experience lack of sedimentation and reduced fluid shear.”

Crystallizing proteins in microgravity can produce better-quality specimens.

“We thought that maybe by crystallizing in microgravity, changing the gravity parameter, we would be able to get good protein crystals, and get the full structure of it,” Chan said. “The crystal-growth process is more controlled without all the turbulence introduced by Earth’s gravity.”

“Since there is evidence that crystals grown in low Earth orbit appear to be more perfect — they are bigger, more ordered, and diffract better in general — we decided to give it a shot,” Chan wrote in his blog post.

Researchers will use these crystals to discover the structures of proteins so that they can develop treatments that are targeted and effective.

Part of their study involves using a molecular "glue" that they could use to anchor the proteins’ tails to their cores, Chan said. With further research they will be able to better understand how these tails and cores interact, which will lead to more refined techniques.

Cancer drugs could then be designed that would bond with the proteins in their initial state, according to an article from the magazine Upward. These would lock the tails and prevent the proteins from adhering to nearby cell membranes — stopping these cancers from growing.

“Drugs are often small molecules that bind to proteins to interfere with their normal functions,” Chan said. “The binding usually involves a set of contacts and electrostatic interactions that are unique to the drug and the protein pocket. A carefully designed drug should fit only to the protein pocket it is designed for, like a key that can only fit into a very specific lock. This way, we can avoid the drug binding to other non-disease-causing proteins and therefore minimize side effects.”

While the team was able to see the 3D structure of protein cores with their molecular glue, they were not yet able to clearly see the tails, and how exactly these structures interact. “We believe maybe our glue wasn't strong enough to really attach the tail strongly to the core, so maybe it was whipping around a little bit,” Chan said. “It was still a step forward.”

Simanshu said that the experiment resulted in better-quality data than similar experiments that were conducted on Earth. “The crystallographic properties of the crystal which was grown in microgravity is certainly better than what we grow on Earth.”

“About 25% of the microgravity crystals were visibly bigger and had nicer appearances (smoother surfaces, sharper edges, etc.),” Chan wrote in his blog post.

“The data collected with X-ray was also better. We saw as much as five-fold improvement in signal-to-noise... this shows that the beauty of our crystals is not only skin-deep; they are beautiful inside as well. With the data-quality improvement, we were finally able to solve protein structures that we could not solve with the Earth crystals before.”

Meanwhile, other cancer researchers continue to partner with the ISS on a variety of experiments as part of the Cancer Moonshot Initiative. In the summer and fall of 2023, the ISS and NASA provided a funding opportunity for further cancer research in space to support this initiative.

Kat Friedrich
Burton Booz
April 2, 202410:00 AM UTC (UTC +0)