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Bruce Stillman

Leemor Joshua-Tor. Photo from CSHL

By Daniel Dunaief

Like many of the other talented and driven professionals at Cold Spring Harbor Laboratory, Leemor Joshua-Tor often works far from the kind of spotlight that follows well-known actors or authors.

That changed in April and early May. First, the American Academy of Arts and Sciences elected her a member on April 11. Other members joining the academy this year include Carol Burnett, New York Times columnist Nicholas Kristof, actor Ian McKellen, who played Gandalf in the Hobbit films and Magneto in the X-Men movies, and Israeli writer David Grossman.

Then, on May 2, the National Science Foundation elected the Cold Spring Harbor Laboratory professor and Howard Hughes medical investigator to join its ranks. “I got a huge amount of congratulatory emails from many friends, some of which I haven’t been in touch with for a while,” Joshua-Tor said. “It’s humbling.”

Joshua-Tor’s research covers a range of areas in structural and molecular biology. She works with RNA interference, where she focuses on how small molecules regulate gene expression or translation. She has also worked with Cold Spring Harbor Laboratory President Bruce Stillman on the early stages of DNA replication.

Early this year, Joshua-Tor and Stillman published a paper in eLife Sciences in which they offered more details about the human origin recognition complex. Stillman suggested that Joshua-Tor was the “main driver” for the research, studying the structure of a protein he had isolated years ago. “I am not a structural biologist, but she is an outstanding one and together, we came up with a very satisfying result.”

The origin recognition complex begins the process of replication, recruiting a helicase, which unwinds DNA. It also brings in regulatory factors that ensure smooth timing and then other factors such as polymerase and a clamp that keeps the process flowing and ensures accurate copying of the genetic code. “We don’t know how ORC’s motor activity is used,” Joshua-Tor explained. “We don’t really know what it is on the DNA that the ORC likes to bind to.”

In the recent work, the scientists explored the ORC’s structure and tinkered with it biochemically to understand it. The ORC binds and hydrolyzes the energy molecule adenosine triphosphate, or ATP, in the same way a motor would, although it probably isn’t continuous. “It might use ATP hydrolysis to perform one sort of movement, perhaps a detachment,” Joshua-Tor suggested.

In the early stages of replication, ATP is necessary for the integrity of the ORC complex, as well as the helicase that gets recruited. “We knew from biochemistry that ORC bounds multiple ATP molecules, but we did not know precisely how,” Stillman explained in an email. “The structure told us. ORC does not open the DNA by itself, but loads a protein complex onto the DNA that, when activated, can open the DNA.” Stillman is working on that process now. The next step for the CSHL collaborators is to get a structure of human ORC bound to DNA.

In their recent work, the researchers characterized how mutations involved in ATP hydrolysis affect a condition called Meier-Gorlin syndrome. Of the mutations they characterized, one affects the ability to hydrolyze ATP. Patients with this syndrome have one copy of the gene with typical function and the other that doesn’t. This likely leaves the patient with half of the molecules to do the required job.

The misregulation of replication is often associated with cancer and is something Joshua-Tor and others consider when they conduct these studies.

ATP, meanwhile, is associated with all kinds of activities, including cell adhesion and taking down misfolded proteins. Many processes in the cell connect to these types of molecular machines.

In her research with RNA interference, she is studying how a microRNA called Let7 is produced. Let7 is involved in development. Before cells differentiate when they are stem cells, they make Let7 continuously and then destroy it. She is studying the pathway for this process. Let7 is absent from stem cells and in some cancers.

Interested in science and theater when she was young, Joshua-Tor grew up in Israel, where she participated in activities at the Weizmann Institute of Science. The institute has biology, biochemistry, chemistry, math, computer science and physics, as well as an archeology unit that didn’t exist when she was there. Later, when she was a graduate student, Joshua-Tor returned to the institute and became an instructor.

An important moment in her scientific development occurred when she was in seventh grade. She was learning about elements and she put each one on a card. She brought these cards to class to study them. Her mother gave her a container that had housed her perfumes, which created a positive association for chemistry every time she studied the elements.

Joshua-Tor was also interested in theater, where she was initially in shows and then became an assistant director. The researcher lives with her daughter Avery, who is 8 and attends the Jack Abrams Magnet School. The tandem have a Schnauzer named Charles Darwin. Her daughter is proud of her mother and tells “anyone that would listen” about the awards her mother recently won, Joshua-Tor said.

Joshua-Tor, whose lab now has 11 people, said she is excited for the opportunity to meet some of her fellow honorees this fall.

Stillman expressed pride in “all our scientists and especially when they make major discoveries and they receive such peer recognition,” he wrote in an email. Joshua-Tor is “one of our best, but we have many scientists who will go on to gain substantial peer recognition. This is her turn, at least for these two awards!”

From left, David Tuveson with Kerri Kaplan, the executive director and chief operating officer of the Lustgarten Foundation, and Sung Poblete, the CEO of Stand Up to Cancer. Photo courtesy of the Lustgarten Foundation

By Daniel Dunaief

Even as David Tuveson was recently fishing for tautog for dinner, he conducted conference calls on a cellphone while watching the clock before an afternoon meeting. A professor at Cold Spring Harbor Laboratory and a world-renowned expert in pancreatic cancer, Tuveson describes the research of some of the students in his laboratory as having considerable bait in the water.

The director of research for the Lustgarten Foundation, Tuveson recently assumed greater responsibility for a larger boat, when he was named director of the Cancer Center at Cold Spring Harbor Laboratory, taking over a role the lab’s president Bruce Stillman held for 25 years. The Cancer Center, which is one part of CSHL, will be in “great hands since Dave Tuveson has wide respect int he cancer community because of his research accomplishments and his talents in leading others,” Stillman explained in an email.

Stillman, who will continue to run his own lab and serve as the President and CEO of CSHL, described Tuveson as a “thought leader” and a “great scientist.” Tuveson and his team of 20 in his laboratory are approaching pancreatic cancer in several directions. They are searching for biomarkers for early detection, developing and testing drugs that preferentially target cancer cells and seeking to uncover the molecular pathways that turn a mutated gene, inflammation, or an illness into a tumor.

Tuveson, who has MD and PhD degrees, focuses on finding ways to use science to help patients. He will continue the Cancer Center’s mission to understand the fundamental causes of the disease, while adding some new strategies. He plans to develop nutrition and metabolism as new areas for the Cancer Center and will recruit “ a few outstanding faculty,” he explained in an email.

CSHL will also expand its skills in immunology and chemistry. Tuveson has dedicated himself and his laboratory to taking innovative approaches to a disease that had received only one-half of 1 percent of the National Cancer Institute’s annual research budget in 1999. That is up to 2 percent today, according to the Lustgarten Foundation, which is the largest private funder of pancreatic cancer research.

Tuveson and his team have become leaders in the developing field of organoids. By taking cells from a tumor or cyst, scientists can produce a smaller copy of the tumor from inside a partial, reproduced patient pancreas. The painstaking work enables researchers to look for the specific type of tumor in a patient, while it also provides a model for testing drugs that might treat the cancer. The technique of growing organoids has become so refined that researchers can create a structure that’s a mix of normal, healthy cells blended with the tumor.

Scientists can then take the resulting structure, called a chimera, and test the effectiveness of therapies in destroying cancers, while monitoring the side effects on healthy cells. Stillman believes Tuveson’s work with pancreas cancer organoids “is at the cutting edge of research in this area.” Tuveson’s lab is using organoids to study what Tuveson, for whom metaphors roll off the tongue as often as characters break into song in Disney movies, describes as kelp-like projections. Each cell has parts that project out from the membrane. His staff is looking for changes in the kelp.

Tuveson is encouraged by work that might help find a subtle protein shift, or changes in the structure of the kelp, as a telltale sign about the type of tumor a patient who is otherwise asymptomatic might have. Doctors might one day screen for these during annual physical exams. Other scientists are so interested in the potential benefits of these organoids that they are attending a training session in Tuveson’s lab that started early this month.

A post doctoral candidate in Tuveson’s lab, Christine Chio, is studying how reactive oxygen affects the growth and stability of cancer. In general, medical professionals have recommended antioxidants to protect health and prevent disease. In pancreatic cancer, however, antioxidants are necessary to keep cancer cells alive. An abundance of reactive oxygen can cause cancer cells to shut down.

“The irony is that cancer cells make their own anti-oxidants and are very sensitive to reactive oxygen — thus we use reactive oxygen to kill cancer cells,” Tuveson explained. Chio, Darryl Pappin, a research professor at CSHL, and several other scientists published their work this summer, in which they identified protein translation as the pathway protected from reactive oxygen species in cancer cells.

At the same time that Tuveson is overseeing the work searching for biomarkers and treatments in his lab, he is also encouraging other research efforts through his work with the Lustgarten Foundation. Started in 1998 when former Cablevision executive Marc Lustgarten developed pancreatic cancer, the Foundation invested $19.4 million in 2015 to pancreatic cancer research and is projected to invest $21 million in 2016.

The mission of the Foundation is to advance research related to the diagnosis, treatment and cure of pancreatic cancer. It also offers patient advice, information and a sense of community through events. Indeed, recently, as a part of a phase 2 clinical trial at Johns Hopkins Kimmel Center, the Foundation offered to provide a free genetic test for microsatellite instability, or MSI, to anyone who might benefit from it as a part of a diagnosis and treatment. MSI occurs in about 2 percent of pancreatic cancer patients. Those with this genetic characteristic responded to a particular type of treatment, called pembrolizumab. The study is still seeking to increase enrollment.

The Foundation is encouraged by the progress scientists like Tuveson have made. “We are hopeful about the future because we know that we have the most talented cancer researchers working on this devastating disease,” Kerri Kaplan, the President and Chief Operating Officer at the Lustgarten Foundation, explained in an email. “We are particularly optimistic about the organoid project and the implications it has for more effective treatments and the work being done on our ‘earlier’ detection program.”

Still, Tuveson and the Foundation, which received donations from 62,000 people in 2015, realize there’s a long way to go. “Pancreatic cancer is an incredibly complex and difficult disease which is why we need to stay focused on funding the most promising research,” Kaplan said.