Identifying New Targets in Cancer Metabolism and Treatment

Progress in cancer research over the past ten years has helped scientists gain a greater understanding of cancer cell metabolism and how cancer cells interact – metabolically speaking – with neighboring cells in the tumor microenvironment in order to secure the nutrients they need to proliferate.

“Learning which conversations between cancer cells and their neighbors to interrupt could potentially point us to new targets for treatments that are more effective than those in use today,” said Deepak Nagrath, associate professor, who joined the BME faculty in January 2017.

In ongoing work begun at Rice University, Nagrath takes a systems biology approach, combining a metabolic isotope tracing technique with a computational framework, together known as 13C-based metabolic flux analysis. He has conducted a number of studies to more fully understand the metabolism of cancer cells as well as their interactions with their immediate environment.

In work published in November 2016 in Cell Metabolism, Nagrath focused on glutamine, an amino acid for which many types of cancer cells have been shown to have a voracious appetite. He also focused on the related enzyme glutamine synthetase in the stroma, or the connective tissue that makes up the tumor microenvironment.

In ovarian cancer cells, Nagrath’s team found greater expression of genes that control glutamine production than in normal cells and that, when the cancer cells were put into a glutamine-deprived environment, surrounding cells known as cancer-associated fibroblasts (CAFs) began producing higher than normal levels of the amino acid.

Upon further investigation, the researchers observed an interesting dynamic between the cancer and stromal cells: The cancer cells appeared to barter with their neighbors. The cancer cells contributed two enzymes, lactate and glutamate, and in exchange, the neighboring CAFs used the enzymes to produce – and share – glutamine.

But when the team inhibited glutamine production by the neighboring CAFs using drugs or through depriving them of nutrients, the ovarian cancer cells stopped growing.

Precisely how ovarian and other types of cancer cells metabolically coax their neighbors to produce nutrients is still not fully known, but Nagrath’s latest work helps snap another important puzzle piece in place.

“We now know that targeting glutamine-producing enzymes in the tumor microenvironment slowed the growth of tumors,” he said. “This suggests to us that using a combination of therapies, rather than just one, to simultaneously target glutamine production and metabolism within cancer cells as well as in their surrounding environment may help us improve treatment.”

The work was funded by a St. Louis Ovarian Cancer Research Awareness grant.

Yang, L. Targeting stromal glutamine synthetase in tumors disrupts tumor microenvironment-regulated cancer cell growth. Cell Metabolism, 24 (2016), 685-700; dx.doi.org/10.1016/j.cmet.2016.10.011


Reading cancer’s chemical clues A nanoparticle-assisted optical imaging technique could one day read the chemical makeup of a tumor.

 

A tumor’s chemical makeup holds valuable clues about how to fight it. But today, it’s difficult or impossible to examine the chemistry inside a tumor. A nanoparticle-assisted optical imaging technique could one day enable doctors to read those clues in real time, providing a non-invasive precision medicine approach that could match treatment to individual tumors.

“Tumors vary widely from one patient to the next, so the more we know about them, the more effective our treatments become. This is especially important with chemotherapy because of its high cost and severe side effects,” said Xueding Wang, a University of Michigan professor of biomedical engineering who helped develop the technique. “This could form the basis of precision medicine treatments that offer better outcomes, fewer side effects and lower costs.”

Most of us are working in the dark with regard to tumor imaging. -Xueding Wang

Doctors already know, for example, that some treatments don’t work on acidic tumors while others are ineffective against tumors that have low oxygen levels. If they know the chemical makeup of a given tumor, they can start the right treatment immediately, then keep close tabs on its effectiveness over time.

In a recent paper, U-M researchers successfully used the process to get a three-dimensional view of the pH level inside tumors in mice, and they believe that they will also be able to use it to read a variety of other important chemical markers inside cancers. The new technology is detailed in a paper published September 7 in Nature Communication.

Images of a mouse tumor obtained with the new technique. Row A shows the presence of the nanoparticle itself, in blue. Row B shows the pH of the tumor. Image C shows oxygen saturation and image D shows hemoglobin concentration. Photo courtesy of Janggun Jo, Michigan Engineering

“Most of us are working in the dark with regard to tumor imaging. There are very few cases where we can study the chemistry of a tumor,” said Wang. ”We hope to change that with this technology, which offers a spatially detailed, real-time look at the chemistry inside a tumor, even when it’s deep inside the body.”

The technique uses a two-part system, starting with a purpose-built, injectable nanoparticle that’s absorbed only by cancerous cells. The particles were loaded with a marker dye that changes color in response to the tumor’s pH to measure acidity.

Wang and Raoul Kopelman, the Richard Smalley Distinguished University Professor of Chemistry, Physics and Applied Physics, made the nanoparticles small enough to fit through tiny cracks in the walls of cancer cells called fenestrations—imperfections that form because cancer cells grow so quickly. They then coated the particles with protein fragments, or peptides, that are attracted to cancerous cells.

“The peptides on the particle are like tugboats guiding an ocean liner,” Kopelman explained.

The particles were injected into mice, where they infiltrated the cancerous cells and the pH-sensitive dye did its work. Next, the team read the dye by flashing pulses of laser light into the tumor from outside the mouse’s body and recording the ultrasound signal that’s reflected back.

Chang Lee, Ph.D., examines the pH-sensitive dye used in the new cancer imaging technique. Photo: Akhil Kantipuly, Michigan Engineering

“Inside the body, the laser’s energy turns from light into heat, then from heat into sound, a bit like thunder,” said Wang. “We can use ultrasound to read that sound energy, then digitally convert it back to optical information. That provides a painless, non-invasive way for us to see the color change in the injected dye, even when it’s deep inside the body.”

The researchers caution that an approved treatment is several years off. But they note that the imaging technology is already under clinical trial, as are the individual components of the nanoparticle. In the meantime, they are working on similar approaches that could be used to measure markers other than pH, like potassium and oxygen levels. They envision a treatment that could measure several different aspects of a tumor’s chemistry using a single scan.

The paper is titled “In vivo quantitative imaging of tumor pH by nanosonophore assisted multi-spectral photoacoustic imaging.” The research was supported by funding from the National Institutes of Health through the National Cancer Institute (grant number R01CA186769).

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Lab-grown lung tissue could lead to new cancer, asthma treatments A look at how Michigan Engineers created a biomaterial scaffold to help researchers from the U-M Medical School grow mature human lung tissue.

In a breakthrough that could one day lead to new treatments for lung diseases like asthma and lung cancer, researchers have successfully coaxed stem cells—the body’s master cells—to grow into three-dimensional lung tissue. This could be useful in future cell-based therapies that repair damaged lungs by cultivating new, healthy tissue.

University of Michigan researchers grew the tissue by injecting stem cells into a specially developed biodegradable scaffold, then implanting the device in mice, where the cells grew and matured into lung tissue. The team’s findings were published in the Nov. 1 issue of the journal eLife.

Briana Dye, a PhD candidate in Cell & Developmental Biology at the University of Michigan Medical School, demonstrates the process of developing lung organoid tissue samples. This research was conducted partly in the lab of Lonnie Shea, the William and Valerie Hall Department Chair and Professor of Biomedical Engineering. Photo: Evan Dougherty, Michigan Engineering Communications & Marketing

Respiratory diseases account for nearly 1 in 5 deaths worldwide, and lung cancer survival rates remain low despite numerous therapeutic advances during the past 30 years. Cell-based therapies could be a key to improving treatment, helping damaged lungs heal in much the same way as a bone marrow transplant can treat leukemia. But the complexity of lung tissue makes such treatments much more difficult to develop.

“Lung tissue needs to be able to form into specific structures like airways and bronchi, and they all need to be able to work together inside the lung. So we can’t just add in healthy adult cells,” said Lonnie Shea, the William and Valerie Hall Department Chair of Biomedical Engineering and a professor of biomedical engineering at U-M. “Instead, we’re looking at delivering the precursors to these cells, then giving them the cues they need to develop and mature on their own. This project was a step in that direction.”

While previous experiments had successfully grown lung cells, the cells were immature and disorganized. So Shea worked with a U-M medical school team led by Briana Dye, a graduate student in the U-M Department of Cell and Developmental Biology, on a new approach. They developed a three-dimensional, biodegradable scaffold that helped the lung cells mature and begin to develop into structures like those inside an actual lung.

Made of PLG, a spongy, biodegradable material, the scaffold was shaped like a small cylinder approximately five millimeters wide and two millimeters tall. The team injected stem cells into the scaffold, transplanted it into mice, then allowed the cells to mature for eight weeks.

The scaffold provided a stiff structure that supported growth of the mini lungs after transplantation while still allowing the transplanted tissue to become vascularized, growing blood vessels that supplied it with nutrients.

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When the team examined the tissue, they found that it had not only survived, it had developed tube-shaped airway structures similar to the airways in adult lungs. It also developed mucus-producing cells, multiciliated cells and stem cells similar to those found in adult lungs.

“In many ways, the tissue grown in the study was indistinguishable from human adult tissue,” says senior study author Jason Spence, Ph.D., associate professor in the U-M Department of Internal Medicine and the Department of Cell and Developmental Biology at the U-M Medical School.

The researchers caution that they’re far from growing anything like a complete human lung—the tissue grown in the experiment was a mass of lung cells scattered among other types of cells inside the scaffold. But they say it’s an important early step that can yield valuable information about how healthy cells grow and develop. In the future, that could lead to new treatments for lung disease.

Richard Youngblood, a second year PhD student in Biomedical Engineering at the University of Michigan, demonstrates the construction of a lung organoid PLG scaffold. This research was conducted partly in the lab of Lonnie Shea, the William and Valerie Hall Department Chair and Professor of Biomedical Engineering. Photo: Evan Dougherty, Michigan Engineering Communications & Marketing

“What if we could regrow a portion of a damaged lung, like a patch?” Shea said. “Treatments like that, while challenging, may be possible.”

The lung tissue is one of several types of cultured organ tissue, or “organoids” that U-M research teams have developed—other cell types they’ve created include intestines, pancreatic cells and placenta cells. In addition to their uses in developing new cell-based therapy, Shea says the cells can provide a human model for screening drugs, studying gene function, generating transplantable tissue and studying complex human diseases like asthma.

“Organoids enable us to see the development and formation of an organ without having to conduct a test on an entire organism. And once we understand that, we can find new ways of repairing organs that are injured, or that haven’t developed properly.”

The paper is titled “A bioengineered niche promotes in vivo engraftment and maturation of pluripotent stem cell derived human lung organoids.” The research was supported by the National Institutes of Health (grant number R01 HL119215), by the NIH Cellular and Molecular Biology training grant at Michigan and by the U-M Tissue Engineering and Regeneration Training Grant.

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‘Sister cell’ profiling aims to shut down cancer metastasis Michigan engineers release individual cells from a specially-designed chip using laser pulses.

In work that could improve understanding of how cancer spreads, a team of engineers and medical researchers at the University of Michigan developed a new kind of microfluidic chip that can capture rare, aggressive cancer cells, grow them on the chip and release single cells on demand.

For the first time, they can easily compare two different “sister” cells – born of the same original cancer cell – to explore how different genes are activated and deactivated as cancer cells divide and spread. Studies with the new chip could also reveal why some cancer cells are resistant to drugs.

Scientist at work in a dark lab

IMAGE:  Yu-Chih Chen views the chip through a microscope. Photo: Evan Dougherty, Michigan Engineering

The ultimate goal of the project – led by Euisik Yoon, a professor of electrical engineering and computer science and corresponding author on the paper in ACS Nano – is to find out what drives the “self-renewal” processes that enable these aggressive cancer cells to behave like stem cells. These cells are known as cancer stem cells – they are capable of dividing and turning into different kinds of cancer cells, with different genes turned on or off. Cancer researchers believe that if the stem-like properties can be switched off, the cancer will not be able to grow and spread.

“When a tumor forms, some cancer stem cells maintain stemness, while others are differentiated. By understanding this, we will know more about tumor formation and discover ways to inhibit it,” said Yu-Chih Chen, a research scientist in electrical engineering and computer science and co-first-author on the paper.

The base of the new chip is composed of carbon nanotubes covered in a plastic coating. When a cancer cell settles on the chip, it sticks itself to that coating. To release the cell, the researchers shone extremely short pulses of laser light near it. The light is readily absorbed by the carbon nanotubes, flash-heating them, while the plastic insulates the cell.

The heat causes trapped air between the nanotubes and plastic to expand, blowing a bubble under the cell. When the bubble bursts through the plastic, the cell detaches. Then, the cell can be flushed out of the chip and captured for genetic profiling.

Gif showing lasers releasing the cell

IMAGE:  The laser creates a bubble under the cell that bursts out and releases the cell so that it can flow out of the chip. Yu-Chih Chen, Yoon Lab, University of Michigan.

Most existing methods for freeing individual captured cancer cells are either damaging to the cells or else cannot get them out of the chip reliably. The laser was precise enough that it could detach one side of a cell, leaving the other side anchored.

And the bubble detachment process was so gentle that even surface proteins on the cell membrane were unscathed. The surface proteins are an important nondestructive avenue for identifying cancer stem cells.

To begin exploring the differences in gene expression between sister cells, the team first looked at a gene called Notch, which is associated with both normal and cancerous stem cells. If Notch was expressed in the daughter cells, it was a rough indication that the division was self-renewing. A Notch-positive cell could go on to produce two cells expressing the same gene, one Notch-positive and one Notch-negative, or two Notch-negative cells.

Their analyses demonstrated that Notch does not serve as a sole indicator for a cancer cell’s stem-like properties. Other genes associated with stem cells could be switched on or switched off in daughter cells with either Notch expression.

Some cells are very resistant; some are easily killedEuisik Yoon, EECS

The task ahead of cancer researchers, with the help of the new chip, is to identify which of these genes are critical to a cancer stem cell’s self-renewing capabilities. If these can be shut down, forcing all cancer stem cells to produce only non-stem cells when they divide, it may be possible to subvert a tumor’s ability to grow and spread.

“If we identify some key genes, or a potential drug target, then pharmaceutical researchers can develop a compound to hit this drug target,” said Chen.

Drug testing inspired Yoon to develop this chip. On earlier chips, some cancer survived treatments, and he wanted to understand these cells better.

“Some cells are very resistant; some are easily killed,” said Yoon. “We wanted to take individual cells out after drug screening and look at their genetic profiles to see if we can see what makes cancer cells stem-like.”

Future experiments could lead to what some cancer researchers call “functional cures,” similar to the management of HIV. The cancer doesn’t necessarily have to be eradicated. Stopping the cancer from spreading may be enough to enable a cancer patient to live a healthy life.

This work is reported in a paper titled “Selective photo-mechanical detachment and retrieval of divided sister cells from enclosed microfluidics for downstream analyses”, appearing today in ACS Nano.

The study was funded in part by the Department of Defense and the National Institutes of Health.

Euisik Yoon is also a professor of biomedical engineering.

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Researchers use ovarian follicles to preserve fertility Technique could be beneficial for women with cancer; study in mice produced live births

From: U-M Comprehensive Cancer Center News
Media contact: Nicole Fawcett, 734-764-2220 |  Patients may contact Cancer AnswerLine™, 800-865-1125

ANN ARBOR, Mich. — Researchers at the University of Michigan have identified a potential new approach to fertility preservation for young cancer patients that addresses concerns about beginning cancer treatment immediately and the possibility of reintroducing cancer cells during the fertility preservation process.

The work, done in mice, has potential to expand options for girls and women undergoing cancer treatments that may impact their future fertility.

The researchers isolated primary ovarian follicles, consisting of the oocyte and surrounding cells. They encapsulated the follicles in a gel and then reimplanted them in mice. All mice transplanted with the follicles resumed normal ovarian cycles. One-third produced live births.

For many young women diagnosed with cancer, concerns about fertility rank high and may influence their decisions about cancer treatment. Current fertility preservation options for women include embryo or egg freezing, performed using hormonal stimulation to induce ovulation. Hormonal stimulation is not possible for all young patients. Some are too young and some cannot afford to delay cancer treatment.

Jacqueline Jeruss“This research is an important advance in the potential expansion of fertility preservation options for young patients who may not be able to undergo hormone stimulation to induce ovulation before beginning chemotherapy,” says study author Jacqueline S. Jeruss, M.D., Ph.D., associate professor of surgery and director of the Breast Care Center at the University of Michigan Comprehensive Cancer Center.

“This study also provides new information on a method to reduce or eliminate cancer cell exposure during the fertility preservation process,” she adds.

Fear of reintroducing cancer

Researchers are also studying ovarian tissue transplantation for patients with cancer. A key concern with this approach is the risk that the ovarian tissue may harbor latent cancer cells that, upon transplantation, could be reintroduced back into the patient. Cancer cells are known to circulate throughout the body even in early stage invasive disease.

In this new study, when researchers isolated the follicles, they substantially reduced the presence of cancer cells. Two of the five tested transplanted materials had no residual cancer cells.

Lonnie Shea“The success rate for traditional in vitro fertilization is approximately 33 percent per cycle. For cancer patients, the oocytes or embryos that are cryo-preserved before cancer treatment may become their entire reproductive future,” says study author Lonnie D. Shea, Ph.D., William and Valerie Hall Chair and professor of biomedical engineering at the University of Michigan.

“The ovary can have tens to hundreds of thousands of follicles. If we can access that pool to preserve fertility, we could potentially create many more chances for reproductive success for these patients,” Shea adds.

Refining the technique

The authors tested three types of biomaterial for preserving the follicles. They hope that by refining their study techniques they can produce even better results. Additional research is also needed to ensure that all cancer cells are consistently eliminated from the follicles every time this tissue is transplanted.

As the work’s promise continues, the researchers envision that ovarian follicles could be extracted and preserved till the woman was ready to pursue pregnancy. At that point, the follicles would be matured and then fertilized. More research is needed before this technique can be tested in humans.

“Fertility is an important part of survivorship for young cancer patients,” Jeruss says. “It’s crucial to identify new techniques to make more fertility preservation options available for women and girls being treated for cancer.”

The study is published in the Nature journal Scientific Reports.

Note to patients: This work was done in mice and is not currently available for use in humans. Call the Cancer AnswerLine at 800-865-1125 to speak to a nurse about available fertility preservation options.

Additional authors: Ekaterina Kniazeva and Teresa K. Woodruff, from Northwestern University; A.N. Hardy from Fox Chase Cancer Center; Samir Boukaidi, from Centre Hospitalier Universitaire de Nice

Funding: National Institutes of Health grant U54 HD076188

Disclosure: None

Reference: Scientific Reports, “Primordial Follicle Transplantation within Designer Biomaterial Grafts Produce Live Births in a Mouse Infertility Model,” published online Dec. 3, 2015,doi:10.1038/srep17709