Glutamine Ratio is Key Ovarian Cancer Indicator

Glutamine plays an important role in cellular growth in several cancers. A Rice University-led study shows how ovarian cancer metabolism changes between early and late stages. In this study, a further link between glutamine dependency and tumor invasiveness is established in ovarian cancer.

A Rice University-led analysis of the metabolic profiles of hundreds of ovarian tumors has revealed a new test to determine whether ovarian cancer cells have the potential to metastasize, or spread to other parts of the body. The study also suggests how ovarian cancer treatments can be tailored based on the metabolic profile of a particular tumor.

The research, which appears online this week in Molecular Systems Biology, was conducted at the Texas Medical Center in Houston by researchers from Rice University, the University of Texas M.D. Anderson Cancer Center, and the Baylor College of Medicine.

Deepak Nagrath, Assistant Professor of Chemical and Biomolecular Engineering at Rice University

“We found a striking difference between the metabolic profiles of poorly aggressive and highly aggressive ovarian tumor cells, particularly with respect to their production and use of the amino acid glutamine,” said lead researcher Deepak Nagrath Ph.D. of Rice University. “For example, we found that highly aggressive ovarian cancer cells are glutamine-dependent, and in our laboratory studies, we showed that depriving such cells of external sources of glutamine — as some experimental drugs do — was an effective way to kill late-stage cells.

“The story for poorly aggressive cells was quite different,” said Nagrath, Assistant Professor of Chemical and Biomolecular Engineering at Rice. “These cells use an internal metabolic pathway to produce a significant portion of the glutamine that they consume, so a different type of treatment — one aimed toward internal glutamine sources — will be needed to target cells of this type.”

The research is part of a growing effort among cancer researchers worldwide to create treatments that target the altered metabolism of cancer cells. It has long been known that cancer cells adjust their metabolism in subtle ways that allow them to proliferate faster and survive better. In 1924, Otto Warburg showed that cancer cells produced far more energy from glycolysis than did normal cells. The Nobel Prize-winning discovery became known as the “Warburg effect,” and researchers long believed that all cancers behaved in this way. Intense research in recent decades has revealed a more nuanced picture.

“Each type of cancer appears to have its own metabolic signature,” Nagrath said. “For instance, kidney cancer does not rely on glutamine, and though breast cancer gets some of its energy from glutamine, it gets even more from glycolysis. For other cancers, including glioblastoma and pancreatic cancer, glutamine appears to be the primary energy source.”

Researchers at Rice University’s Laboratory for Systems Biology of Human Diseases analyzed the metabolic profiles of hundreds of ovarian tumors and discovered a new test to determine whether ovarian cancer cells have the potential to metastasize. Study co-authors include, from left, Julia Win, Stephen Wahlig, Deepak Nagrath, Hongyun Zhao, Lifeng Yang and Abhinav Achreja.

Nagrath, director of Rice University’s Laboratory for Systems Biology of Human Diseases, said the new metabolic analysis indicates that ovarian cancer may be susceptible to multidrug cocktails, particularly if the amounts of the drugs can be tailored to match the metabolic profile of a patient’s tumor.

The research also revealed a specific biochemical test that pathologists could use to guide such treatments. The test involves measuring the ratio between the amount of glutamine that a cell takes up from outside and the amount of glutamine it makes internally.

“This ratio proved to be a robust marker for prognosis,” said University of Texas M.D. Anderson Cancer Center co-author Anil Sood, M.D., Professor of Gynecologic Oncology and Reproductive Medicine and co-director of the Center for RNA Interference and Non-Coding RNA. “A high ratio was directly correlated to tumor aggression and metastatic capability. Patients with this profile had the worst prognosis for survival.”

The three-year study included cell culture studies at Rice as well as a detailed analysis of gene-expression profiles of more than 500 patients from the Cancer Genome Atlas and protein-expression profiles from about 200 M.D. Anderson patients.

“The enzyme glutaminase is key to glutamine uptake from outside the cell, and glutaminase is the primary target that everybody is thinking about right now in developing drugs,” Nagrath said. “We found that targeting only glutaminase will miss the less aggressive ovarian cancer cells because they are at a metabolic stage where they are not yet glutamine-dependent.”

Lifeng Yang, Study Lead Author & Graduate Student, Systems Biology of Human Diseases, Rice University

Rice University graduate student Lifeng Yang, lead author of the study, designed a preclinical experiment to test the feasibility of a multidrug approach, involving the use of a JAK inhibitor and a glutaminase inhibitor. This “drug cocktail” approach inhibited the early stage production of internal glutamine, while also limiting the uptake of external glutamine.

“That depleted all sources of glutamine for the cells, and we found that cell proliferation decreased significantly,” Yang said.

Nagrath said the study also revealed another key finding — a direct relationship between glutamine and an ovarian cancer biomarker called “STAT3” (Signal Transducer And Activator Of Transcription 3).

“A systems-level understanding of the interactions between metabolism and signaling is vital to developing novel strategies to tackle cancer,” said M.D. Anderson co-author Prahlad Ram Ph.D., Associate Professor of Systems Biology and co-director of the M.D. Anderson Cancer Center’s Systems Biology Program. “STAT3 is the primary marker that is used today to ascertain malignancy, tumor aggression and metastasis in ovarian cancer.”

Nagrath said, “The higher STAT3 is, the more aggressive the cancer. For the first time, we were able to show how glutamine regulates STAT3 expression through a well-known metabolic pathway called the TCA cycle, which is also known as the ‘Krebs cycle.’”

Nagrath said the research is ongoing. Ultimately, Dr. Nagrath hopes the investigations will lead to new treatment regimens for cancer as well as a better understanding of the role of cancer-cell metabolism in metastasis and drug resistance.

Co-authors include Hongyun Zhao, Stephen Wahlig, Abhinav Achreja and Julia Win (all affiliated with Rice University); Tyler Moss, Lingegowda Mangala, Guillermo Armaiz-Pena, Dahai Jiang, Rajesha Roopaimoole, Cristian Rodriguez-Aguayo, Imelda Mercado-Uribe, Gabriel Lopez-Berestein and Jinsong Liu (all affiliated with M.D. Anderson Cancer Center); Juan Marini of Baylor College of Medicine; and Takashi Tsukamoto of Johns Hopkins University.

The research was supported by seed funding from (i) the Collaborative Advances in Biomedical Computing Program at Rice Univesity’s Ken Kennedy Institute for Information Technology, (ii) Rice University’s John and Ann Doerr Fund for Computational Biomedicine, (iii) the Odyssey Fellowship Program at the MD Anderson Cancer Center, (iv) the estate of C.G. Johnson Jr., (v) the National Institutes of Health, (vi) the Cancer Prevention and Research Institute of Texas, (v) the Ovarian Cancer Research Fund, (vi) the Blanton-Davis Ovarian Cancer Research Program, (vii) the Gilder Foundation, and (viii) the MD Anderson Cancer Center.

Sources: 

• “Glutamine ratio is key ovarian cancer indicator,” by Jade Boyd, Press Release, Rice University, May 5, 2014.

• Yang L, et. al. “Metabolic shifts toward glutamine regulate tumor growth, invasion and bioenergetics in ovarian cancer.” Mol Syst Biol. (2014) 10: 728. DOI: 10.1002/msb.20134892, published May 5, 2014.

Ovarian Cancer Cells Are More Aggressive On Soft Tissues

When ovarian cancer spreads from the ovaries it almost always does so to a layer of fatty tissue that lines the gut. A new study has found that ovarian cancer cells are more aggressive on these soft tissues due to the mechanical properties of this environment. The finding is contrary to what is seen with other malignant cancer cells that seem to prefer stiffer tissues.

Professor Michelle Dawson and graduate student Daniel McGrail used traction force microscopy to measure the forces exerted by cancer cells on soft and stiff surfaces. (Photo Credit: Rob Felt, Georgia Institute of Technology)

“What we found is that there are some cancer cells that respond to softness as opposed to stiffness,” said Michelle Dawson, an assistant professor in the School of Chemical and Biomolecular Engineering at the Georgia Institute of Technology. “Ovarian cancer cells that are highly metastatic respond to soft environments by becoming more aggressive.”

Ovarian cancer cells spread, or metastasize, by a different method than other cancer cells. Breast cancer cells, for example, break off from a solid tumor and flow through the blood until they arrest in small blood vessels. The cancer cells then penetrate the vessel surface to form a tumor. Because ovarian tumors are in the abdomen, these cancer cells are shed into the surrounding fluid and not distributed through the blood. They must be able to adhere directly to the fatty tissue that lines the gut, called the omentum, to begin forming a tumor. The new study discovered details about how ovarian cancer cells seem to prefer the mechanical properties of this soft tissue.

The study was published in a recent advance online edition of the Journal of Cell Science and was sponsored by the National Science Foundation and the Georgia Tech and Emory Center for Regenerative Medicine.

The research team, led by Daniel McGrail, a graduate student in the Dawson lab, found that ovarian cancer cells in vitro were more adherent to a layer of soft fat cells than a layer of stiffer bone cells, and that this behavior was also repeated using gels of similar rigidities.

“All the behaviors that we associate with breast cancer cells on these more rigid environments are flipped for ovarian cancer cells,” Dawson said.

After adhering to these soft surfaces, metastatic ovarian cancer cells became more aggressive. Their proliferation increased and they were less responsive to chemotherapeutics. The ovarian cancer cells were also more motile on soft surfaces, moving nearly twice as fast as on rigid surfaces.

The team also found that less aggressive cells that do not metastasize do not exhibit any of these changes.

The researchers used techniques that haven’t been traditionally used in the study of ovarian cancer. They measured the force exerted by the cells by tracking the displacement of beads in the environment around the cells. The researchers found that the metastatic cells increased their traction forces – used to generate motion – by three-fold on soft surfaces, but no such change was present in the less aggressive cells.

“We think the behavior that metastatic ovarian cancer cells exert on these soft surfaces is representative of the mechanical tropism that they have for these softer tissues in the gut,” Dawson said.

In future work, the researchers will investigate whether ovarian cancer cells have some natural inclination towards this uniquely more aggressive behavior in softer environments.

“We’re trying to find out whether there is some internal programming that leads to this aggressive behavior,” Dawson said.

This research is supported by the National Science Foundation under award number 1032527, and the Georgia Tech and Emory Center for Regenerative Medicine under award number 1411304. Any conclusions or opinions are those of the authors and do not necessarily represent the official views of the sponsoring agencies.

Source:  McGrail DJ, et al., “The malignancy of metastatic ovarian cancer cells is increased on soft matrices through a mechanosensitive Rho-ROCK pathway.” (Journal of Cell Science, 2014). http://dx.doi.org/10.1242/?jcs.144378.

“Decisions Are Made By Those Who Show Up”*

Responding to a threat of a funding reduction to the Department of Defense’s Ovarian Cancer Research Program, during the last week of October the Ovarian Cancer National Alliance urged advocates to contact their Members of Congress to appeal to the Appropriations Defense Subcommittee to increase funding for the research program. As a result of the Ovarian Cancer National Alliance’s advocacy efforts, 14 Senators and 77 Representatives showed their opposition to the funding cut by signing a Dear Colleague letter sent to the Subcommittee Tuesday, November 3, 2009. …

Advocates Work To Prevent Slash In Ovarian Cancer Research Funding

Responding to a threat of a funding reduction to the Department of Defense’s Ovarian Cancer Research Program, during the last week of October the Ovarian Cancer National Alliance (OCNA) urged advocates to contact their Members of Congress to appeal to the Appropriations Defense Subcommittee to increase funding for the research program.

Advocates lobbying on Capitol Hill for increased funds for ovarian cancer research. (Photo: Ovarian Cancer National Alliance)

As a result of OCNA’s advocacy efforts, 14 Senators and 77 Representatives showed their opposition to the funding cut by signing a Dear Colleague letter sent to the Subcommittee Tuesday, November 3, 2009.

The Dear Colleague letter, written by Senator Robert Menendez (D-NJ) and Congresswoman Rosa DeLauro (D-CT), requested that the Subcommittee allocate the $25 million set forth in the U.S. House of Representatives‘ version of the Defense bill, and not the $10 million outlined in the U.S. Senate version of the bill. The Senate funding level represented a 50 percent reduction from the $20 million appropriated in fiscal year (FY) 2009.

The date of the conference subcommittee meeting has yet to be announced.

Established in 1997, the Department of Defense’s Ovarian Cancer Research Program has received $10 million in funding annually from FY 1998 until FY 2008. However, for FY 2009, the program’s funding was doubled to $20 million. The Ovarian Cancer Research Program works to eliminate ovarian cancer by conducting innovative, multidisciplinary research on early detection, screening and treatment of ovarian cancer.

To read the full text of the letter and see if your elected officials signed, please click here.

The Ovarian Cancer Action Network periodically sends out action alerts to notify advocates of pressing issues that need constituent support. To sign up, please click here.

About the Ovarian Cancer National Alliance

OCNA is the advocacy arm of the ovarian cancer movement. OCNA works with federal policy makers, including the  U.S. President, U.S. Congress, and federal agencies like the U.S. Food and Drug Administration (FDA) and the Centers for Medicare and Medicaid Services (CMS). OCNA commits its resources to be a voice for ovarian cancer survivors and significantly reduce the number of deaths from this deadly disease by advocating at the federal level for the following:

• Adequate and sustained funding for ovarian cancer research and awareness programs, and

• Legislation that improves quality of life and access to care for ovarian cancer patients.

Since 1997, when OCNA was founded, death rates from ovarian cancer have not significantly changed. However, OCNA has worked to increase funding for ovarian cancer research, with the goal that this funding will support breakthroughs to help detect ovarian cancer early, treat it more thoroughly, and allow women with ovarian cancer to survive, and thrive.

OCNA has worked to ensure that (i) necessary treatments are covered by Medicare, (ii) drugs and tests on the market are safe and effective, and (iii) federal policy makers are aware of the importance of the ovarian cancer community.

Join OCNA to fight for women with ovarian cancer, and policies that help support them and their families.

Source: Advocates Work To Prevent Slash In Ovarian Cancer Research Funding, News Update, Ovarian Cancer National Alliance, November 11, 2009.

*Title Quote:  Fictional U.S. President Josiah Edward Bartlet, What Kind of Day Has It Been Episode, The West Wing, created by Aaron Sorkin, originally aired May 17, 2000 [Sorkin attributes his teleplay quote to Woody Allen (“80% of success in life is just showing up”)].

Stand Up To Cancer Funded Research Dream Team Takes Aim At Women’s Cancers

Stand Up To Cancer (SU2C), the Entertainment Industry Foundation’s charitable initiative supporting groundbreaking research aimed at getting new cancer treatments to patients in an accelerated timeframe, has reached a significant milestone, awarding the first round of three-year grants — that total $73.6 million — to five multi-disciplinary, multi-institutional research Dream Teams. … Each Dream Team’s project, funded for three years pending satisfactory achievement of stated milestones, is “translational” in nature, geared toward moving science from “bench to bedside” where it can benefit patients as quickly as possible. …

A Dream Team of leading cancer researchers will accelerate development of drugs to attack a mutated [PI3K] molecular pathway that fuels endometrial, breast and ovarian cancers, funded by a three-year $15 million grant awarded today by [SU2C] … Genetic aberrations in the network, known as the PI3K pathway, are found in half of all breast cancer patients, 60 percent of all cases of endometrial cancer and 20 percent of ovarian cancer patients. Other cancers that include a mutationally activated PI3K pathway include melanoma, colon and prostate cancers, brain tumors, and leukemia.