• The gene SRFP2 had been thought to curb tumor growth.
• That’s not what UNC’s Nancy Klauber-DeMore found.
• DeMore, a surgeon with a penchant for basic research, developed a new drug—the only one that specifically targets SFRP2 in breast tumors.
Something didn’t add up. A lab in Spain had reported that the gene SFRP2 kept a protein called beta-catenin in check. And if you put the brakes on beta-catenin, you curb tumor growth. So scientists thought SFRP2 acted as a natural tumor suppressor.
But when UNC’s Nancy Klauber-DeMore ran years’ worth of experiments to find genes that might aid tumor growth, there was SFRP2. It was overexpressed during the formation of blood vessels in malignant breast tumors—a good sign that it was aiding tumor growth.
How was this possible?
DeMore, a surgeon, became a detective in the middle of a scientific controversy. Did SFRP2 suppress tumors or help them grow?
Brave new research
DeMore’s interest in the formation of microscopic blood vessels—also known as angiogenesis—began when she was a 19-year-old undergraduate at Wheaton College in Massachusetts. “I loved molecular biology, and my physiology professor worked on angiogenesis,” she says. “That’s when I read all of Judah Folkman’s papers.” Folkman is credited with founding the field of tumor angiogenesis. DeMore reached out and went to Harvard to meet him.
Inspired by his work, she considered getting a doctorate to focus on angiogenesis research, but she chose to become a medical doctor instead; working with patients mattered to her. “I really wanted to know how research was clinically relevant,” she says. During her surgical residency, she worked as a research fellow under Folkman for three years. After that—and a fellowship in surgical oncology at Memorial Sloan-Kettering Cancer Center—DeMore pursued a job as a breast surgeon. But she also wanted to continue her angiogenesis work.
“To do both, you need a home department with a strong commitment to research,” she says. “There actually aren’t a lot of surgery departments in the country you can say that about. UNC is one of them; that’s one of the reasons I chose to come here.”
During her first year at UNC, she came up with an idea to pinpoint genes that are overexpressed in microscopic blood vessels. It was novel, but the NIH rejected her proposal. “They said it wasn’t technically feasible,” DeMore says. So she set out to prove it was.
With private grants, including one from a foundation her own patients started, she worked for three years to figure out how to stain breast tissue samples in such a way that allowed her team to identify blood vessels that fed tumor growth.
Using a camera attached to a microscope, DeMore’s team looks at the stained tissue samples on a computer screen and circles specific vessels. Then the microscope uses a laser to cut out the circled section. This is called microdissection. Just one lab had proven that it was possible to use the technique to extract RNA from single cells; DeMore’s lab now specializes in it.
Once cut from the sample, the dissected tissue falls into a pool of RNA buffer—a solution that stabilizes the sample and allows DeMore’s team to extract RNA from the cells. Then the lab measures gene expression during angiogenesis.
The NIH took notice and gave her a grant to continue her work.
The team quickly identified 55 genes that were substantially overexpressed in malignant samples. Using an online database, DeMore found that six of the genes were either on the cell membrane or on secreted proteins through the cell membrane. Those sorts of genes make the easiest targets for drugs. That whittled her list to a handful of suspects. One of them was SFRP2.
“This made no sense,” DeMore says. And that’s why she focused on it.
Before DeMore started her latest study, scientists who had studied SFRP2 believed that the gene played a role in suppressing tumor growth.
But DeMore says that those scientists conducted experiments using cell cultures. “No one had ever looked at SFRP2 in actual human tumors,” she says.
When DeMore found that SFRP2 was overexpressed in malignant tumors, she set out to describe how it activates angiogenesis. Turns out that SFRP2 triggers the expression of NFAT proteins, which stimulate angiogenesis.
With that piece of information in hand, she teamed up with UNC pharmacologist Russ Mumper to create an antibody—a drug molecule—to suppress SFRP2. The results were impressive.
In mouse models, the drug triggered a 67 percent reduction of new blood vessels in malignant tumors and a 50 percent reduction in tumor size. And DeMore found that her antibody—the only drug that targets SFRP2—reduces tumors that don’t respond to Avastin, a popular drug for certain cancer types.
DeMore’s lab also found that targeting SFRP2 did not, in fact, block beta-catenin. “That was a major concern,” DeMore says. Turns out, the original research about SFRP2’s suppressing angiogenesis was on the wrong track.
DeMore’s drug, meanwhile, shows great promise, though approval for clinical use is still a ways off.
The road ahead
DeMore’s research is unique—she started with human tissue samples from UNC’s procurement facility and then used a mouse model to find the exact mechanism to suppress the SFRP2 gene.
“I think that’s why this is promising,” she says. “One of the pitfalls of the past was that people spent a lot of time discovering drug targets in mouse tumors.” But many of those discoveries haven’t panned out; they don’t seem to be as relevant to human tumors as researchers had hoped.
DeMore is now seeking funding to start clinical trials. For that, she and UNC cardiologist Cam Patterson—DeMore’s mentor and collaborator—formed the start-up company Enci Therapeutics. Along with developing antibodies, the company works with pharmaceutical companies to create clinical trials.
Fundraising—it’s a common crossroads for researchers. Let’s hope she’s not there for too long.