Texas A&M Research Shows Biological Clocks Could Improve Brain Cancer Treatment

Biological clocks throughout the body play a major role in human health and performance, from sleep and energy use to how food is metabolized and even stroke severity. Now, Texas A&M University researchers found that circadian rhythms could hold the key to novel therapies for glioblastoma, the most prevalent type of brain cancer in adults—and one with a grim prognosis.

Scientists in the Texas A&M Center for Biological Clocks Research (CBCR) determined that the timed production of a particular protein, associated with tumor proliferation and growth, is disrupted in glioblastoma cells, and they believe that this may lead to a more effective technique to treat the cancerous cells without damaging the healthy surrounding tissue. These findings, which were supported in part by the National Institutes of Health, were published today (Jan. 10) in the international journal BMC Cancer.

Texas A&M biologist Deborah Bell-Pedersen, PhD, a co-corresponding author on the study, found in her previous research that the biological clock in the model fungal system Neurospora crassa controls daily rhythms in the activity of a signaling molecule, called p38 mitogen activated protein kinase (MAPK). This signaling protein plays a role in glioblastoma’s highly invasive and aggressive properties.

In the new research, David J. Earnest, PhD, a mammalian biological clocks expert at the Texas A&M College of Medicine and co-corresponding author on the study, collaborated with Bell-Pedersen to show that the clock controls daily rhythms in p38 MAPK activity in a variety of mammalian cells as well, including normal glial cells, the supporting “helper” cells surrounding neurons.

Furthermore, their work found that such regulation is absent in glioblastoma cells. “We tested to see if inhibition of this cancer-promoting protein in glioblastoma cells would alter their invasive properties,” said Bell-Pedersen, an internationally recognized leader in the fields of circadian and fungal biology. “Indeed, we found that inhibition of p38 MAPK at specific times of the day—times when the activity is low in normal glial cells under control of the circadian clock—significantly reduced glioblastoma cell invasiveness to the level of noninvasive glioma cells.”

These findings indicate that glioblastoma might be a good candidate for chronochemotherapy, meaning treating cancer at specific times of day to get the most impact.

“Chronotherapeutic strategies have had a significant positive impact on the treatment of many types of cancer by optimizing the specific timing of drug administration to improve the efficacy and reduce the toxicity of chemotherapy,” Bell-Pedersen said. “However, circadian biology has not been applied to the development of chronotherapeutic strategies for the treatment of glioblastoma, and clinical outcomes for this common primary brain tumor have shown limited improvement over the past 30 years.”

Glioblastomas gained some attention this summer when Senator John McCain was diagnosed with the condition. “A big reason for poor prognosis for patients with this aggressive type of tumor is that the glioblastoma cells rapidly and unabatedly invade and disrupt the surrounding brain cells,” said Gerard Toussaint, MD, a clinician and assistant professor at the Texas A&M College of Medicine who specializes in glioblastoma. Current treatments—including chemotherapy, surgical resection, immunotherapy and radiation—are largely ineffective in prolonging life expectancy beyond 18 months.

“We found that an inhibitor of p38 MAPK activity would make the cells behave less invasively, and if you can control the invasive properties, you can improve prognosis,” Earnest said. In addition, the team’s data indicate such treatment may be more effective and less toxic if administered at the appropriate time of the day.

This reduced toxicity is important, because a drug to inhibit the cancer-promoting activity of this protein was tested but found to be too harmful, with too many side effects. “If treatment with the drug can be timed to when the normal glial cells naturally have low activity of p38 MAPK, the addition of the drug might not be as toxic for these cells, and yet would still be very effective on the cancerous cells,” Earnest said.

Although promising, the current studies were done using cell cultures. The team’s next step is to test p38 inhibitor chronochemotherapy in an animal model for glioblastoma. If successful, they would then move on to clinical trials.

“We work on a model system, and the reason to do that is that we can make progress quickly, and we always hope that what we’re working on will lead to something useful, and I think this is a prime example of how putting effort into basic research can pay off,” Bell-Pedersen said. “We’re very hopeful and encouraged by our data that we’ll find a treatment.”

KU Reseachers Find Statins May Hold Keys to Future Cancer Treatment

Researchers at the University of Kansas Medical Center have found that high doses of drugs commonly used to fight high cholesterol can destroy a rogue protein produced by a damaged gene that is associated with nearly half of all human cancers.

Tomoo Iwakuma, M.D., Ph.D., an associate professor in the Department of Cancer Biology, and his team have published the first research showing how the use of statins, such as Lipitor (atorvastatin), Crestor (rosuvastatin) and Mevacor (lovastatin), can shut down structurally mutated p53 proteins that can accelerate cancer progression, while not harming proteins produced by healthy p53 genes. Although statins are not a cancer treatment per se, the understanding of how they affect mutated forms of p53 could lead to new medications designed specifically to knock out the damaged p53.

“I could have kept working for 20 years or longer without any big finding,” said Iwakuma, whose work appeared in the November 2016 issue of Nature Cell Biology and has been recommended for F1000Prime, a prestigious peer-review service that identifies research that is likely to influence biomedical and clinical knowledge. “This is the most exciting work of my science life, because it will contribute to treating cancer.”

P53 gene and cancer

Cancer is essentially caused by mutations to the genes that regulate cell growth or cell death. Of the hundreds of genetic culprits that have been implicated with causing various cancers, p53, dubbed the “guardian of the genome,” is the mightiest of them all. Mutant forms of p53 have been found in nearly half of all malignant tumors and nearly every type of human cancer.

When p53 works properly, it produces proteins that keep cells from growing and dividing too quickly. When p53 becomes mutated, either spontaneously or through heredity, its regulating abilities no longer work and cells can grow out of control, forming tumors and invading normal tissues – that’s cancer.

Compounding the problem that mutant p53 can no longer suppress the growth of tumors is that fact that it can also actually accelerate the progression of cancer and drug resistance.

The challenge for Iwakuma and his team was to find out how to eliminate the misbehaving protein, while leaving cells containing healthy p53 needed for normal cell growth unharmed.

Hunting for a weapon

Four years ago, Iwakuma and his lab team collaborated with the High Throughput Screening Laboratory (HTC) on the University of Kansas Lawrence campus to screen compounds to find out which ones might degrade mutant p53. Of the nearly 9,000 compounds they tested, about 2,400 were Food and Drug Administration (FDA)-approved drugs, while the others were non-FDA approved and uncharacterized compounds.

When Iwakuma got an email from the HTC listing the 10 compounds that the screenings had shown promise in reducing mutant p53 levels, he was shocked to see that some of them were statins.

“At first I thought, ‘What? This must be wrong,'” said Iwakuma, who first became interested in p53 as a post-doctoral student at the University of Texas MD Anderson Cancer Center.

Early screenings often produce false positives, so Iwakuma had to verify the lab results, first testing them in cells and then in mice. The KU researchers injected the mice with cells expressing mutant p53, waited for tumors to form, and then treated them with high doses of statins for 21 days. They found that tumors did not grow well in mice treated with statins compared to the controls, and they learned the statins worked only on structurally mutated (misfolded) p53, as opposed to p53 mutated at the spot where it binds to DNA. This was an important discovery, particularly since clinical research with statins had not considered the type of p53 mutation.

“We found that only the structural mutation is affected,” Iwakuma said. “Which explains why clinical studies with statins were inconclusive.”

Just the beginning

While the team was elated with its findings, the researchers knew their work was just beginning.

“Once we knew for sure statins degraded mutant p53, we still had to figure out how,” explained Atul Ranjan, Ph.D., a post-doctoral researcher in cancer biology at KU and co-author on the study. “We needed to find out exactly how the statins work for p53 degradation; which other proteins are involved in the mechanism.”

So Alejandro Parrales, Ph.D., another co-author on the study and a post-doc in Iwakuma’s lab, began looking at heat shock proteins, which are known for their efforts to correct misfolded proteins, as a possible piece to the puzzle. The researchers identified DNAJA1 as a heat shock protein that binds to misfolded mutant p53 and thus protects the mutant p53 from an enzyme that flags damaged or misshapen proteins for destruction.

It turned out that the same mechanisms that help statins reduce cholesterol are at work preventing mutant p53 from binding to DNAJA1, leaving these mutant proteins unprotected. As a result, mutant p53 is free to attach to the enzyme that leads to its degradation. And since mutant p53 is not usually present in normal cells, all this happens without affecting healthy cells.

Going forward, researchers know that many challenges await them, including finding ways to target DNAJA1 directly, now that they know its absence results in mutant p53 being degraded. Iwakuma also sees potential to use statins or another p53-degrading drug in conjunction with chemotherapy.

Mutant p53 makes human cancer cells more metastatic and resistant to chemotherapy,” he said. “That’s a primary reason to get rid of it — to improve survival in cancer patients.”

Reducing Radiation Successfully Treats HPV-Positive Oropharynx Cancers and Minimizes Side Effects

Human papillomavirus-positive oropharynx cancers (cancers of the tonsils and back of the throat) are on rise. After radiation treatment, patients often experience severe, lifelong swallowing, eating, and nutritional issues. However, new clinical trial research shows reducing radiation for some patients with HPV-associated oropharyngeal squamous cell carcinomas can maintain high cure rates while sparing some of these late toxicities.

“We found there are some patients have very high cure rates with reduced doses of radiation,” said Barbara Burtness, MD, Professor of Medicine (Medical Oncology), Yale Cancer Center, Disease Research Team Leader for the Head and Neck Cancers Program at Smilow Cancer Hospital, and the chair of the ECOG-ACRIN head and neck committee. “Radiation dose reduction resulted in significantly improved swallowing and nutritional status,” she said.

The study, published in the December 26 issue of the Journal of Clinical Oncology, showed that patients treated with reduced radiation had less difficulty swallowing solids (40 percent versus 89 percent of patients treated with standard doses of radiation) or impaired nutrition (10 percent versus 44 percent of patients treated with regular doses of radiation).

“Today, many younger patients are presenting with HPV-associated squamous cell carcinoma of the oropharynx,” said Dr. Burtness. “And while traditional chemoradiation has demonstrated good tumor control and survival rates for patients, too often they encounter unpleasant outcomes that can include difficulty swallowing solid foods, impaired nutrition, aspiration and feeding tube dependence,” said Dr. Burtness. “Younger patients may have to deal with these side effects for decades after cancer treatment. We want to help improve our patients’ quality of life.”

The study included 80 patients from 16 ECOG-ACRIN Cancer Research Group sites who had stage three or four HPV-positive squamous cell carcinoma of the oropharynx, and were candidates for surgery. Eligible patients received three courses of induction chemotherapy with the drugs cisplatin, paclitaxel, and cetuximab. Patients with good clinical response then received reduced radiation.

Study results also showed that patients who had a history of smoking less than 10 packs of cigarettes a year had a very high disease control compared with heavy smokers.

St. Jude Researchers Reveal How Two Types of Immune Cells Can Arise From One

The fates of immune cells can be decided at the initial division of a cell. Researchers at St. Jude Children’s Research Hospital have discovered that the production of daughter cells with different roles in the immune system is driven by the lopsided distribution of the signaling protein c-Myc. Nudging c-Myc in one direction or the other could make vaccines more effective or advance immunotherapies for cancer treatment. The research appears online today in the scientific journal Nature.

Asymmetric cell division generates two types of cells with distinct properties. This type of cell division is essential for producing various cell types and plays an important role in development. Rather than producing two identical daughter cells, the cells undergoing asymmetric division produce daughter cells that are fated for vastly different roles. In the case of activated T cells, researchers knew that one daughter cell became the rapidly dividing effector T cells that launch the immediate attack on infectious agents and other threats. The other daughter cell became the slowly dividing memory T cells that function like sentries to provide long-term protection against recurring threats. Until now, the mechanism underlying the process was unknown.

“Our study shows that the way in which the regulatory protein c-Myc distributes during asymmetric cell division directly influences the fate and roles of activated T cells,” said corresponding author Douglas Green, Ph.D., St. Jude Department of Immunology chair. “We also show how this asymmetry is established and sustained.”

The researchers worked with cells growing in the laboratory and in mice. Scientists showed that during asymmetric cell division of activated T cells, high levels of c-Myc accumulated in one daughter cell. There, c-Myc functioned like a shot of caffeine to launch and sustain the rapid proliferation of effector T cells, including those in mice infected with the influenza virus. In contrast, the daughter cells with low levels of c-Myc functioned like memory T cells, proliferating to mount an immune response a month later when mice were again exposed to the virus.

Researchers also identified the metabolic and signaling pathways that serve as a positive feedback loop to sustain the high levels of c-Myc that effector T-cells require to maintain their identities and function. The scientists showed that disrupting certain components of the system disturbed c-Myc production, which altered the fate of T cells and caused effector T cells to operate like memory T cells.

“Our work suggests that it may be possible to manipulate the immune response by nudging production of c-Myc in one direction or the other,” Green said. “Potentially that could mean more effective vaccines or help to advance T-cell immune therapy for cancer treatment.”

c-Myc is an important transcription factor that regulates expression of a variety of genes and plays a pivotal role in cell growth, differentiation and death via apoptosis (programmed cell death). Excessive or inappropriate production of c-Myc is a hallmark of a wide variety of cancers. Previous research from Green and his colleagues showed that c-Myc also drives metabolic changes following T cell activation. The metabolic reprogramming fuels proliferation of effector T cells. “Activated T cells divide every four to six hours. There is no other cell in adults that can divide that fast, not even cancer cells,” Green explained.

In this study, the researchers observed several metabolic changes that arose from the way c-Myc partitioned in the cell. These metabolic changes help regulate the way the cells divide, proliferate and differentiate. In a series of experiments, researchers showed how manipulating that system could affect T cell fate following asymmetric cell division by modifying production of c-Myc. “While daughter cells of activated T cells seem to have very different fates, we showed their behavior could be altered by manipulating these metabolic and regulatory pathways to increase or decrease c-Myc levels.” Green said.

Asymmetric cell division is an important driver of other fundamental processes in cells, including early embryonic development and the self-renewal of stem cells.

“Similar control mechanisms exist in other cells that divide asymmetrically, including stem cells in the digestive and nervous systems,” he added.