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Assistant Professor Tobias Janowitz

By Daniel Dunaief

This is part 2 of a two-part series.

Cancers not only compromise human health, but they can also suppress the body’s immune response. A little studied small protein called cystatin C, which is secreted by numerous cells, may render the immune system less effective in its response to tumors.

Sam Kleeman, a PhD student in Cold Spring Harbor Laboratory Assistant Professor Tobias Janowitz’s lab, recently published results in the journal Cell Genomics that demonstrate a link between elevated levels of this protease inhibitor, the suppression of the immune system, and the development of cancer.

Kleeman was able to demonstrate a potential role “Cystatin C might play in damping down the immune response to tumors,” he said.

Cystatin C is a known cysteine protease inhibitor, but the biological and organ-level relevance of this has not been characterized in detail. This protein could be one of many mechanisms by which glucocorticoids can reduce the effectiveness of the immune system.

Cystatin C could drive the progression of the disease, which could explain why Kleeman has found evidence that higher levels coordinate with worse outcomes.

Starting with the data

Pursuing an interest in data- driven research, Kleeman, who has a Bachelor of Medicine and Surgery from New College at the University of Oxford, searched the UK Biobank, which provides health data for numerous people in the United Kingdom. 

In this Biobank, Kleeman, who joined Cold Spring Harbor Laboratory in August of 2020, found that cystatin C was the best prognostic indicator of cancer deaths.

“I was a little surprised by this,” Kleeman said as he had heard of cystatin C as a marker of kidney function, but was not aware of any association with cancer mortality. Some studies had found evidence for this previously, but those were in small cohorts and were poorly understood, he explained.

A healthy kidney clears most proteins quickly, pumping it out into urine. A kidney that’s not functioning optimally, however, allows it to accumulate.

In his research, Kleeman removed cystatin C selectively in cancer cells, causing the tumors to grow more slowly. The main changes in the architecture of the tumor was that it reduced the frequency of macrophages with expression of a protein called Trem2. While the exact mechanism is not known, it’s likely that immune control of the tumor increases without cystatin C.

Kleeman also demonstrated a similar effect on the connection between levels of Covid-19 and mortality in a paper published in iScience.

The biological mechanism explaining the correlation is nuanced. Patients with higher levels of glucocorticoids can be associated with poor outcomes. It is not a simple relationship, he said, which makes causality difficult to assess.

Kleeman believes cystatin C secretion in response to glucocorticoids has context dependency. Not all cells posses inducible cystatin C secretion.

The research primarily found that only macrophages and cancer cells can secrete cystatin C in response to glucocorticoids.

He describes a “two hit” model, by which glucocorticoids plus an inflammatory stimulus recruit macrophages. The model applies to all inflammatory stores, but is co-opted in the case of cancer.

At this point, drugs aren’t available to inhibit or reduce cystatin C. Instead, Kleeman suggested that a viable research target route might involve creating a specific antibody.

Some researchers have created so-called knockout mice, which don’t have this protein. These mice can survive without it, although eliminating all cystatin C creates other problems.

Kleeman speculated that the protein could play a role in preventing significant immune reaction against sperm.

Indeed, this protein is secreted at high levels in the testes. Males without it have lower sperm function and production.

Kleeman hopes this work acts as a starting point to understand the mechanism better by which glucocorticoids modify immune response to cancer, and to investigate cystatin C as a possible therapeutic target.

Long standing partnership

As an undergraduate, Kleeman took a class with Janowitz, which kicked off a mentorship that now spans two continents.

Kleeman appreciates the comfort level Janowitz has in working on higher-risk, higher-reward topics or on ideas that haven’t already attracted considerable attention from other scientists.

“There’s a tendency in science towards group think,” Kleeman said. In the history of medicine and science, many widely accepted theories turn out to be wrong. “Patients undoubtedly benefit from a diversity of thought in science and medicine,” he explained.

When he completes his PhD, Kleeman said it would be a “dream to have a dual appointment” in which he could conduct research and work in the clinic with patients. To get there, he knows he needs to establish his research profile that includes a genuine track record of achievement while demonstrating that he can function as a reliable and effective clinician.

Kleeman’s thesis research lies outside the field of cystatin C, which started out as a curiosity and developed into the recent publication. He wanted to “understand what UK Biobank could teach us about cancer patients.” With Janowitz and Cold Spring Harbor Laboratory Professor Hiro Furukawa, Kleeman is working to understand how a specific type of cancer could cause an auto-immune disease.

A resident of Forest Hills, Kleeman lives about 45 minutes from the lab. Outside of work, he enjoys visiting national parks. He has visited 10 so far, including Yosemite National Park, Zion and Rocky Mountain National Park. 

Professionally, Kleeman feels it is a privilege to be a PhD student. He appreciates that he can explore his interests without too many restrictions and is eager to make the most of the opportunity.

From left, Sam Kleeman, Assistant Professor Tobias Janowitz, Miriam Ferrer Gonzalez and Emma Davidson. Photo by Caryn Koza/CSHL

By Daniel Dunaief

This part one of a two part series.

It’s a bit like shaking corn kernels over an open flame. At first, the kernels rustle around in the bag, making noise as they heat up, preparing for the metamorphosis.

That’s what can happen in any of the many laboratories scattered throughout Long Island, as researchers pursue their projects with support, funding and guidance from lab leaders or, in the science vernacular, principal investigators.

Sometimes, as happened recently at the benches of Cold Spring Harbor Laboratory Assistant Professor Tobias Janowitz, several projects can pop at around the same time, producing compelling results, helping advance the careers of developing scientists and leading to published papers.

PhD graduate Miriam Ferrer Gonzalez and MD/ PhD student Sam Kleeman recently published separate studies.

In an email, Janowitz suggested the work for these papers is “time consuming and requires a lot of energy.” He called the acceptance of the papers “rewarding.” 

In a two-part series, Times Beacon Record News Media will describe the research from each student. This week, the focus is on Ferrer Gonzalez. Check back next week for a profile of the work of Kleeman.

Miriam Ferrer Gonzalez

Miriam Ferrer Gonzalez. Photo by Caryn Koza/CSHL

Miriam Ferrer Gonzalez was stuck. She had two results, but couldn’t seem to figure out how to connect them. First, in a mouse model of the ketogenic diet — heavy on fats, without including carbohydrates —cancer tumors shrunk. That was the good news.

The bad news, which was even more pronounced than the good, was that this diet was not only starving the tumors, but was triggering an earlier onset of cachexia, in which bodies weaken and waste away. The cachexia overpowered the mice, causing them to die sooner than if they had a normal diet.

Ferrer, a student in residence from Spain who was conducting her research at Cold Spring Harbor Laboratory while earning her PhD at the University of Cambridge in the UK, thought the two discoveries were paradoxically uncoupled. A lower tumor burden, she reasoned, should have been beneficial.

In presenting and discussing her findings internally to the lab group, Ferrer received the kind of feedback that helped her hone in on the potential explanation.

“Finding out the mechanism by which a ketogenic diet was detrimental for both the body and the cancer was the key to explaining this uncoupling,” Ferrer explained.

The adrenal glands of mice fed a ketogenic diet were not producing the necessary amount of the hormone corticosterone to sustain survival. She validated this broken pathway when she discovered higher levels of corticosterone precursors that didn’t become functional hormones.

To test this hypothesis, she gave mice dexamethasone, which boosted their corticosterone levels. These mice had slower growing tumors and longer lives.

Ferrer recently published her paper in the journal Cell Metabolism.

To date, the literature on the ketogenic diet and cancer has been “confusing,” she said, with studies that show positive and negative effects.

“In our study, we go deeper to explain the mechanism rather than only talking about glucose-dependency of cancer cells and the use of nutritional interventions that deprive the tumor of glucose,” said Ferrer. She believed those factors are contributing to slower tumor growth, but are not solely responsible.

Thus far, there have been case studies with the ketogenic diet shrinking tumors in patients with cancer and, in particular, with glioblastoma, but no one has conducted a conclusive clinical trial on the ketogenic diet.

Researchers have reported on the beneficial effects of this diet on epilepsy and other neurological diseases, but cancer results have been inconclusive.  For the experiments in Janowitz’s lab, Ferrer and technician Emma Davidson conducted research on mouse models.

Ferrer, who is the first author on the paper, has been working with this system for about four years. Davidson, who graduated from the College of Wooster in Ohio last year and is applying to MD and MD/PhD programs, contributed to this effort for about a year.

Next steps

From left, Emma Davidson, Assistant Professor Tobias Janowitz, Sam Kleeman and Miriam Ferrer Gonzalez. Photo by Caryn Koza/CSHL

Now that she earned her PhD, Ferrer is thinking about the next steps in her career and is considering different institutions across the country. Specifically, she’s interested in eating behavior, energy homeostasis, food intake and other metabolic parameters in conditions of stress. She would also like to focus on how hormonal cycles in women affect their eating behavior.

Originally from a small city in Spain called Lleida, which is in the western part of Catalonia, Ferrer appreciated the opportunity to learn through courses and conferences at Cold Spring Harbor Laboratory.

Until she leaves the lab in the next few months, Ferrer plans to work with Davidson to prepare her to take over the project for the next year.

The follow up experiments will include pharmacologically inducing ferroptosis of cancer cells in mice fed a ketogenic diet. They hope to demonstrate that early induction of ferroptosis, or a type of programmed cell death, prevents tumor growth and prevents the tumor-induced reprogramming of the rest of the body that causes cachexia.

These experiments will involve working with mice that have smaller and earlier tumors than the ones in the published paper. In addition, they will combine a ketogenic diet, dexamethasone and a ferroptosis inducing drug, which they didn’t use in the earlier experiments.

Janowitz has partnered with Ferrer since 2018, when she conducted her master’s research at the University of Cambridge. As the most senior person in Janowitz’s lab, Ferrer has helped train many of the people who have worked in his lab. She has found mentoring rewarding and appreciates the opportunity to invest in people like Davidson.

Ferrer, who is planning a wedding in Spain in September, is a fitness and wellness fan and has taken nutrition courses. She does weight lifting and running.

Ferrer’s parents don’t have advanced educational degrees and they supported their three children in their efforts to earn their degrees.

“I wanted to be the best student for my parents,” said Ferrer, who is the middle child. She “wanted to make my parents proud.

The hand off

Emma Davidson and Miriam Gonzalez Ferrer examine an adrenal gland sample section from a cachectic mouse. Photo by Caryn Koza/CSHL

For her part, Davidson is looking forward to addressing ways to implement further treatment methods with a ketogenic diet and supplemental glucocorticoids to shrink tumors and prevent cachexia. 

Davidson appreciated how dependable Ferrer was during her time in the lab. Just as importantly, she admired how Ferrer provided a “safe area to fail.”

At one point, Davidson had taken all the cells she was planning to use to inject in mice. Ferrer reminded her to keep some in stock.

“Open lines of communication have been very beneficial to avoid more consequential failures,” Davidson said, ”as this mistake would have been.”

Davidson developed an interest in science when she took a high school class called Principles in Biological Science and Human Body Systems. When she was learning about the cardiovascular system, her grandfather had a heart attack. In speaking with doctors, Davidson acted as a family translator, using the language she had studied to understand what doctors were describing.

Like Ferrer, Davidson lives an active life. Davidson is preparing for the Jones Beach Ironman Triathlon in September, in which she’ll swim 1.2 miles, bike 56 miles and run a half marathon. She plans to train a few hours during weekdays and even more on weekends for a competition she expects could take about six hours to complete.

Davidson started training for these events with her father Mark, an independent technology and operations consultant and owner of Exoro Consulting Group.

Longer term, Davidson is interested in medicine and research. After she completes her education, she will try to balance between research and clinical work.