Posted on Leave a comment

Disconnect between brain's dopamine system and cocaine addiction

Researchers at The University of Texas at San Antonio have revealed significant insight into cocaine addiction, a phenomenon which has grown significantly in the United States since 2015.

Now new data by UTSA shows how the release of the neurotransmitter dopamine changes when working for cocaine. Our brains naturally release dopamine to reward us for working hard for something gratifying, for example, enjoying a sweet piece of chocolate. Yet when it comes to illicit substances such as cocaine, the harder the effort put into getting cocaine, the less likely there will be a large jolt of dopamine.

With the new understanding that there is a difference between how the brain responds to additional effort in relation to a specific object of desire, either food vs. illicit drugs, the UTSA data suggests that this new finding into the dopamine production complex could help guide future solutions for drug addiction.

“By identifying these differences, you can come up with pharmacological or behavior strategies so you can maintain normal responses for natural rewards but at the same time manage the responses for drugs,” says Matthew Wanat, assistant professor in the Department of Biology at UTSA.

Dopamine is a neurotransmitter that plays key roles in the brain and body. The chemical messenger is involved in regulating physical movement. It’s a catalyst for a person to be able to engage in motivated behaviors and also facilitates learning. Scientific studies show that a disruption in dopamine production can lead to neurological disorders such as Parkinson’s but also drug addiction.

Wanat’s previous research showed that there is a larger dopamine response when we delay gratification for food. Now his work on cocaine adds another dimension which can aid to solve the complex puzzle of the impact of illicit drug use on brain chemistry. The latest UTSA research will be published in an upcoming issue of the Journal of Neuroscience.

Professor Wanat and post-doctoral fellow Idaira Oliva, the lead researcher on the project, used rats that were trained to work for infusions of cocaine. The rodents in order to obtain the desired stimulant, had to engage in a progressive series of nose pokes before getting another dose of cocaine. Later, voltammetry measurements of the dopamine levels in the rats’ brain were taken while they worked to obtain cocaine.

As to why there is an opposite effect of dopamine surge in cocaine usage with added effort is still not fully understood. However, UTSA scientists don’t necessarily think it’s related to the actual drug.

“We think there might be a change in the subjective value. It’s just perceived as less valuable. It fits in with the idea that you don’t like the drug as much,” says Wanat. “They (drug users) want it but they don’t like it as much as they would.”

Although much of the recent drug crisis which impacts the country has centered on opioids, cocaine usage in the United States has surged since 2015. The latest Centers for Disease Control data suggests that after marijuana, cocaine is the second most abused illicit drug, and deaths have grown by 37%. Moreover, the DEA shows that another factor for increased cocaine usage is the boom in global cultivation and coca production of the psychostimulant.

The independent effects of illicit drugs are difficult to tease out. Many drug users tend to rely on several abused substances and the interplay between them and the combined impact on the body is not understood. For now, researchers at UTSA will still continue future investigations on what beyond dopamine causes addiction.

“This effect is not due to cocaine levels in the brain, it’s something upstream to what’s getting the dopamine neurons to fire,” says Wanat.

Story Source:

Materials provided by University of Texas at San Antonio. Note: Content may be edited for style and length.

Posted on Leave a comment

Bioinspired nanoscale drug delivery method

Washington State University researchers have developed a novel way to deliver drugs and therapies into cells at the nanoscale without causing toxic effects that have stymied other such efforts.

The work could someday lead to more effective therapies and diagnostics for cancer and other illnesses.

Led by Yuehe Lin, professor in WSU’s School of Mechanical and Materials Engineering, and Chunlong Chen, senior scientist at the Department of Energy’s Pacific Northwest National Laboratory (PNNL), the research team developed biologically inspired materials at the nanoscale that were able to effectively deliver model therapeutic genes into tumor cells. They published their results in the journal, Small.

Researchers have been working to develop nanomaterials that can effectively carry therapeutic genes directly into the cells for the treatment of diseases such as cancer. The key issues for gene delivery using nanomaterials are their low delivery efficiency of medicine and potential toxicity.

“To develop nanotechnology for medical purposes, the first thing to consider is toxicity — That is the first concern for doctors,” said Lin.

The flower-like particle the WSU and PNNL team developed is about 150 nanometers in size, or about one thousand times smaller than the width of a piece of paper. It is made of sheets of peptoids, which are similar to natural peptides that make up proteins. The peptoids make for a good drug delivery particle because they’re fairly easy to synthesize and, because they’re similar to natural biological materials, work well in biological systems.

The researchers added fluorescent probes in their peptoid nanoflowers, so they could trace them as they made their way through cells, and they added the element fluorine, which helped the nanoflowers more easily escape from tricky cellular traps that often impede drug delivery.

The flower-like particles loaded with therapeutic genes were able to make their way smoothly out of the predicted cellular trap, enter the heart of the cell, and release their drug there.

“The nanoflowers successfully and rapidly escaped (the cell trap) and exhibited minimal cytotoxicity,” said Lin.

After their initial testing with model drug molecules, the researchers hope to conduct further studies using real medicines.

“This paves a new way for us to develop nanocargoes that can efficiently deliver drug molecules into the cell and offers new opportunities for targeted gene therapies,” he said.

The WSU and PNNL team have filed a patent application for the new technology, and they are seeking industrial partners for further development.

Story Source:

Materials provided by Washington State University. Note: Content may be edited for style and length.

Posted on Leave a comment

Decades-old question about protein found in Alzheimer's brain plaques

Alzheimer’s-affected brains are riddled with so-called amyloid plaques: protein aggregates consisting mainly of amyloid-β. However, this amyloid-β is a fragment produced from a precursor protein whose normal function has remained enigmatic for decades. A team of scientists at VIB and KU Leuven led by professors Joris de Wit and Bart De Strooper has now uncovered that this amyloid precursor protein modulates neuronal signal transmission through binding to a specific receptor. Modulating this receptor could potentially help treat Alzheimer’s or other brain diseases. The results are published in Science.

More than 30 years have passed since the amyloid precursor protein was first identified. In the late 1980s, several research teams across the globe traced the protein fragment found in amyloid plaques back to a gene located on chromosome 21. The gene encodes a longer protein that is cleaved into several fragments, one of which ends up in amyloid plaques.

Decades of research have focused on the cleavage process that leads to the formation of the amyloid-β fragment and its subsequent aggregation, in the hope of identifying new therapeutic avenues for Alzheimer’s. Meanwhile, an important question remained unanswered: what does the rest of the amyloid precursor protein actually do?

In search of a binding partner

To answer this question, Dr. Heather Rice, a postdoctoral researcher in the labs of Joris de Wit and Bart De Strooper at the VIB-KU Leuven Center for Brain & Disease Research, set out to identify the nerve cell receptor that interacts with the amyloid precursor protein.

“We knew that the amyloid precursor protein exerts its role through the part of the protein that is released outside of the cell. To understand its function, we needed to look for binding partners located on the cell surface,” explains Rice.

The researchers identified a receptor present at the synapse, the structure where two different neurons connect to pass on signals. “We found that the secreted part of the amyloid precursor protein interacts with a receptor called GABABR1a, and that this in turn suppressed neuronal communication at the synapse,” says Rice.

Modulating signal transmission

“Although mutations in the amyloid precursor protein in familial cases of Alzheimer’s disease all affect the production of amyloid-β, we don’t really know whether other aspects of the protein’s function contribute to Alzheimer’s as well,” says Bart De Strooper. He believes that the new findings add a fresh perspective to previous studies on the amyloid precursor protein and Alzheimer’s disease. “The newly identified role of the amyloid precursor protein may underlie the neuronal network abnormalities we see in mouse models of Alzheimer’s disease and preceding clinical onset in human patients. It is exciting to consider that a therapy targeting this receptor might attenuate these abnormalities in people with Alzheimer’s.”

De Wit adds that the clinical implications may reach much further than just Alzheimer’s: “Interestingly, GABABR signaling has been implicated in a diverse range of neurological and psychiatric disorders, including epilepsy, depression, addiction and schizophrenia. Now that we know how the secreted part of the amyloid precursor protein modulates neuronal signaling through the GABAB receptor, we could think of new ways to develop drugs that can restore this type of neuronal signaling in other clinical contexts.”

Story Source:

Materials provided by VIB (the Flanders Institute for Biotechnology). Note: Content may be edited for style and length.

Posted on Leave a comment

HIV protein function that slows migration of T cells also improves viral survival

A study from a Massachusetts General Hospital (MGH) research team has identified the specific function of a protein found in HIV and related viruses that appears to slow down viral spread in the earliest stages of infection. But they also found that, after initially slowing down the spread of infection, that function may help the virus survive later on by evading the immune response. Their report has been published in Cell Host & Microbe.

“HIV uses several proteins with a number of functions predicted to change the migratory patterns of infected cells,” says Thorsten Mempel, MD, PhD, of the MGH Center for Immunology and Inflammatory Diseases, senior author of the report. “Our investigation identified a particular function of the protein Nef as responsible for disrupting the ability of infected T cells to migrate, slowing the rate at which the virus initially spreads after infection. However, that same function allowed the virus to persist at a later time when the adaptive immune response — especially the response of cytotoxic ‘killer’ T cells — has become activated. These findings suggest that this function of Nef evolved to help HIV evade the immune response but at the expense of initially slower spread in an infected animal.”

Recent studies by Mempel’s team and others have suggested that — in contrast to the conventional view that HIV spreads throughout the body as free viral particles — the virus can be transported by infected T cells that travel through tissues and the circulatory system and then spread the infection by direct contact with uninfected cells. Since Nef has previously been shown both to downregulate the function of several proteins involved in signal transduction and to disrupt processes thought to drive cellular migration, the MGH team took a detailed look at exactly how Nef and other HIV proteins exert their effects on the motility of infected T cells.

Their experiments in mice with key elements of a human immune system — the only animal model capable of being infected with HIV — supported previous findings that Nef reduces the migration of infected cells by disrupting the assembly and disassembly of a protein called actin into branched filaments. Actin filaments support the shape of cells and enable them to move by pushing the outer membrane out on one side while retracting the membrane on the other end. This function of Nef is carried out through the interaction of a “hydrophobic patch” — a group of water-repelling amino acids closely spaced on the surface of the protein — with a group of cellular proteins including an enzyme called PAK2.

In the first weeks after female mice were vaginally inoculated with two strains of HIV — one with a mutated form of Nef in which the hydrophobic patch is disrupted and one unmutated strain — the Nef-mutant strain became dominant, implying that T cells infected with that strain had spread the infection more rapidly than those with the unmutated strain. But over time the mutant strain disappeared and the unmutated strain of HIV became dominant, coinciding with increased activity of the anti-HIV cytotoxic T cell response. The authors also found that the benefit to viral survival conferred by the hydrophobic patch on the unmutated form of Nef was not seen in cellular studies, suggesting that it had developed in response to the immune system pressures present in a live animal.

“We know that other functions of Nef appear to have evolved primarily to help HIV evade the immune response, so it makes sense that disruption of the actin cytoskeleton serves a similar purpose,” says Mempel, who is an associate professor of Medicine at Harvard Medical School. “The fact that this appears only in living animals clearly suggests that important biological properties of the virus are not apparent in the cell culture systems traditionally used to study HIV. This means there is still a lot to discover about what HIV can do and what its potential weaknesses are. Importantly, if it becomes possible to target the ability of Nef to disrupt the cytoskeleton, we may be able to increase the vulnerability of HIV to antiviral treatment strategies, such as vaccination or broadly neutralizing antibodies.”

The co-lead authors of the Cell Host & Microbe report are Shariq Usmani, PhD, MGH Center for Immunology and Inflammatory Diseases (CIID), and Thomas Murooka, PhD, University of Manitoba. Additional co-authors are Maud Deruaz, PhD, Radwa Sharaf, Mauro Di Pilato, PhD, Vladimir Vrbanac, Andrew Tager, MD, and Andrew Luster, MD, PhD, MGH CIID; Karen Power and Todd Allen, PhD, Ragon Institute of MGH, MIT and Harvard; and Paul Lopez, Ryan Hnatiuk, and Wan Hon Koh, PhD, University of Manitoba. Support for the study includes National Institutes of Health grants AI097052, DA036298, and AI078897.

Story Source:

Materials provided by Massachusetts General Hospital. Note: Content may be edited for style and length.

Posted on Leave a comment

Hidden culprit in heart failure

An international research team led by scientists at the University of Alberta have pinpointed a hidden culprit that leads to dilated cardiomyopathy — a dangerous condition that accounts for 20 per cent of all cases of heart failure — which opens the door to potential new treatments that could help counter the threat.

The team identified a key molecule named PI3K alpha that binds to gelsolin — an enzyme that can destroy filaments that help make up the structure of the heart’s cells — and suppresses it.

The researchers, led by Gavin Oudit, a professor of cardiology at the U of A and director of the Heart Function Clinic at the Mazankowski Alberta Heart Institute, believe the molecule holds great promise as a possible therapeutic target, offering a possible path forward to personalized and precision medicine for patients with dilated cardiomyopathy.

The condition decreases the heart’s ability to pump blood because its main pumping chamber, the left ventricle, is enlarged and weakened. Researchers studied the condition at the molecular level in animal models and in explanted human hearts, and found that the pathway leading to dilated cardiomyopathy is common in all species.

According to Oudit, who holds the Canada Research Chair in Heart Failure, the condition is caused by biomechanical stress, which activates the gelsolin enzyme.

“You need some gelsolin, but when it gets out of control, it destroys things. The molecule chews up the filaments and you get really bad heart failure,” said Oudit. “But we have also shown that when you suppress this molecule, you preserve your heart function. It’s intact.”

Oudit said the potential impact on patient care is huge.

“By understanding these patients better, we’ll hopefully be able to develop specific therapies for them,” he said.

According to Oudit, there are currently no specific treatments for patients with heart failure. The same medications are used for all patients.

“But if we can now identify patients that have problems with this type of remodelling (dilated cardiomyopathy), we can target them specifically,” he explained. “That’s where we’re heading down the road. And to take this research right from the molecule to our patients, it’s very rewarding.”

Story Source:

Materials provided by University of Alberta Faculty of Medicine & Dentistry. Note: Content may be edited for style and length.

Posted on Leave a comment

Study suggests how to treat diastolic heart failure

Research out of University Minnesota Medical School and published in the Journal of Clinical Investigation Insight uncovers what causes diastolic heart failure and how it can be treated.

In the article, “Magnesium supplementation improves diabetic mitochondrial and cardiac diastolic function,” author Samuel Dudley, MD, PhD, Academic Chief of Cardiology at the University of Minnesota Medical School and his fellow researchers found that magnesium can be used to treat diastolic heart failure.

“We’ve found that cardiac mitochondrial oxidative stress can cause diastolic dysfunction. Since magnesium is an essential element for mitochondrial function, we decided to try the supplement as a treatment,” explained Dudley. “It eliminated the poor heart relaxation that causes diastolic heart failure.”

Obesity and diabetes are known risk factors for cardiovascular disease. Researchers discovered the magnesium supplement also improved the mitochondrial function and blood glucose in the subjects.

Patients with diastolic heart failure have a high morbidity, mortality, and healthcare costs. Patients with this condition have similar annual mortality to patients with systolic heart failure, and up until now there was no known specific treatments for this type of heart failure.

“This is an exciting step forward in the cardiovascular field,” said Dudley, “Right now there are no specific treatments for patients with diastolic heart failure, but now we have a theory of why diastolic heart failure occurs and what we can do to get rid of it.”

The next step is human trials. Dudley says this work could also open doors for answers for a related condition, atrial fibrillation.

Story Source:

Materials provided by University of Minnesota Medical School. Note: Content may be edited for style and length.

Posted on Leave a comment

Mutation in sodium-potassium pump: Newly discovered serious disease in children

Two children from Europe and a child from Canada suffer from a previously unknown disease that causes epileptic seizures, loss of magnesium in urine and reduced intelligence at the same time — though unfortunately without it being possible to treat or alleviate their symptoms.

But researchers in an international consortium have now discovered what is wrong with the children aged 4, 6 and 10. Professor Bente Vilsen and her research group at the Department of Biomedicine at Aarhus University, Denmark, are part of the consortium, which also includes researchers from universities in Germany, England, Austria, the Netherlands and Canada. The research results have been published in the American Journal of Human Genetics.

Using a genetic analysis, the researchers have discovered that the disease is caused by a newly occurring mutation in one of the sodium-potassium pump’s four forms, known as the Alpha-1 form. Even though the children have exactly the same three symptoms, they do not have the same genetic defect, as the amino acids in the pump protein which are genetically altered are different, explains Bente Vilsen.

“It turns out that the form of sodium-potassium pump which mutates is found in both the kidneys and the brain. The mutation leads to the kidneys, which normally absorb magnesium, instead secreting the substance in the urine; however, it is not the loss of magnesium which triggers the epileptic seizures. The convulsions occur because the sodium-potassium pump is also extremely important for the brain’s functions, meaning that giving extra magnesium supplements won’t help prevent the seizures,” says Bente Vilsen.

She adds that the third frightening sign of the disease, mental retardation, should probably be attributed to a lack of oxygen to the brain during the seizures.

The children share the common trait that the mutations have destroyed the pump functioning that Jens Christian Skou received the Nobel Prize in Chemistry in 1997 for discovering. This knowledge is important because understanding the role of the sodium-potassium pump is the first step towards developing effective treatment methods. The research group is now working towards this goal, even though the disease is most likely rare.

“But three cases have turned up in two different places in Europe and in Canada, and they’re not likely to be the only ones,” says Bente Vilsen. She explains that the new knowledge about the disease will probably mean that medical doctors will in future be more aware that loss of magnesium in combination with epilepsy may be caused by genetic defects in the sodium-potassium pump.

“I believe that we will in future find many more children with the disease, and that this is a good example of why international research cooperation is absolutely necessary — there are simply too few cases of the disease for a single country to carry out the research alone,” says Bente Vilsen.

She points out that in future, it will be possible to replace sick genes with healthy, and that it is therefore important to know precisely which gene is affected by a mutation. She also points out that the understanding of the disease mechanisms causing rare diseases often turns out to lead to better treatment of patients with related but far more commonly occurring diseases.

Jens Chr. Skou’s sodium-potassium pump is best known as the membrane pump that is needed for the normal functioning of nerve cells, kidney cells and most of the body’s other cells.

The pump works like a battery that separates sodium and potassium on either side of the membrane. This creates an electrical current across the cell membrane that drives many other processes such as e.g. electric conduction along the nerve cells and the absorption of magnesium and a range of nutrients from the urine into the kidney cells, so that they are not normally lost in the urine.

Jens Christian Skou, who died in early summer at the age of 99, originally had the idea that mutations in the sodium-potassium pump would be incompatible with life. But it has since been found that more serious diseases which are not necessarily fatal are due to genetic defects in the sodium-potassium pump — and this is precisely the case with the disease that the three children suffer from.

This is due to two factors. Firstly, that in the body’s different types of tissues there are several variants of the sodium-potassium pump which are able to supplement each other if one of the forms does not work. And, secondly, that we have genetic material from both our parents, so even in the kidneys, which in contrast to the brain only contain one variant of the sodium-potassium pump (Alpha-1), not all of the sodium-potassium pumps will be defective, but only those derived from one of the two parents.

Therefore, in both the brain and kidneys, there will be a reduced number of functioning sodium-potassium pumps, but not a total absence of pumps — because if this was the case, the children would have died before birth as predicted by Jens Christian Skou.

In the specific research project, the patients were discovered by medical doctors working in clinical practice. Bente Vilsen’s group have contributed with their expertise in examining sick sodium-potassium pumps by inserting the diseased gene in cultured cells that originally come from monkey kidneys, making it possible to measure their pump function in the laboratory. As it turned out, the three mutations each in their own way caused the pump to be unable to transport sodium and potassium.

There is a long way to go before the research results benefit the patients as the discovery is as such basic research. However, Bente Vilsen explains that Postdoc Rikke Holm from her research group recently discovered how it was possible to use an additional mutation — a so-called ‘rescue’ mutation — to nullify the effects of the disease mutations on the pump’s binding of sodium.

“This provides an insight into the molecular mechanism which we in the research group are working to utilise to improve the pump’s transport activities, meaning that we can possibly one day develop a drug with a similar ‘rescue-effect’. In any event, that’s our hope. The fact is that it’s basic research which generates the knowledge that forms the basis for the development of the vast majority of drugs and forms of treatment,” points out Bente Vilsen.

Posted on Leave a comment

Viral production is not essential for deaths caused by food-borne pathogen

The replication of a bacterial virus is not necessary to cause lethal disease in a mouse model of a food-borne pathogen called Enterohemorrhagic Escherichia coli (EHEC), according to a study published January 10 in the open-access journal PLOS Pathogens by Sowmya Balasubramanian, John Leong and Marcia Osburne of Tufts University School of Medicine, and colleagues. The surprising findings could lead to the development of novel strategies for the treatment of EHEC and life-threatening kidney-related complications in children.

EHEC is a Shiga toxin-producing pathogen associated with serious disease outbreaks worldwide, including more than 390 food-poisoning outbreaks in the U.S. in the last two decades. Humans acquire EHEC by ingesting contaminated food or water, or through contact with animals or their environment. Infection may progress to life-threatening hemolytic uremic syndrome (HUS), the leading cause of kidney failure in children. Treatment for EHEC or HUS remains elusive, as antibiotics have been shown to exacerbate disease. The bacteria begin to produce Shiga toxin when a virus present in the EHEC genome is induced to leave its dormant state and begin to replicate, a process promoted by many antibiotics. Until now, it was generally believed that extensive virus replication was necessary for the bacteria to produce sufficient toxin to cause disease.

Using an EHEC disease mouse model, the authors show that an inducing signal needed to begin viral replication is essential for lethal disease. But surprisingly, sufficient Shiga toxin was produced to cause lethal mouse disease, even without viral replication. According to John Leong, one of the authors, “An important next step will be to learn what parts of the viral life cycle occur in human patients, and whether there are ways to prevent those aspects that lead to disease.”

Story Source:

Materials provided by PLOS. Note: Content may be edited for style and length.

Posted on Leave a comment

Cancer: Drug fights formation of metastasis

The most deadly aspect of breast cancer is metastasis. It spreads cancer cells throughout the body. Researchers at the University and the University Hospital of Basel have now discovered a substance that suppresses the formation of metastases. In the journal Cell, the team of molecular biologists, computational biologists, and clinicians reports on their interdisciplinary approach.

The development of metastasis is responsible for more than 90% of cancer-related deaths, and patients with a metastatic disease are considered incurable. The interdisciplinary team led by Prof. Nicola Aceto from the Department of Biomedicine at the University of Basel has identified a drug that suppresses the spread of malignant cancer cells and their metastasis-seeding ability.

Precursors of metastases: Circulating tumor cell clusters

Circulating tumor cells (CTCs) are cancer cells that leave a primary tumor and enter the bloodstream, on their way to seeding distant metastases. These so-called CTCs can be found in the blood of patients as single cells or cell clusters. CTC clusters are the precursors of metastases. The Basel research team has discovered that CTC cluster formation leads to key epigenetic changes that facilitate metastasis seeding. These changes enable CTC clusters to mimic some properties of embryonic stem cells, including their ability to proliferate while retaining tissue-forming capabilities. The scientists have also shown that these epigenetic changes are fully reversible upon the dissociation of CTC clusters.

In their search for a substance that suppresses metastasis development, the research team tested 2486 FDA-approved compounds used for a number of different indications. They found inhibitors with the unexpected ability to dissociate patient-derived CTC clusters. This drug-based dissociation of CTC clusters into individual cells also resulted into epigenetic remodeling and prevented the formation of new metastases.

Preventing metastasis versus killing cancer cells

“We thought of acting differently from standard approaches, and sought to identify drugs that do not kill cancer cells, but simply dissociate them,” states Nicola Aceto, holder of an ERC starting grant and SNSF professorship.

In the fight against breast cancer, metastases remain the greatest danger. These new findings on the mechanisms of metastasis formation are the result of a large collaborative effort across various disciplines. “Our ambitious approach would not have been possible without collaboration with outstanding clinicians, molecular and computational biologists, with the support of state-of-the-art technology platforms,” says Aceto and adds: “Our methodology is positioned directly at the interface between these different disciplines. We are already working on the next step, which is to conduct a clinical trial with breast cancer patients.”

Story Source:

Materials provided by University of Basel. Note: Content may be edited for style and length.

Posted on Leave a comment

Uncovering more options in cancer immunotherapy

To make it possible for cancer immunotherapy to help more people, think small.

Small molecules, that is.

A major class of cancer immunotherapy agents, known as checkpoint inhibitors, revive the activity of immune cells that cancer cells have lulled to sleep. Generally, these agents are antibodies: highly specific, yet bulky proteins that do not easily diffuse through the body.

If scientists want to boost immune cells’ ability to kill cancer cells, then plenty of other tools — vast libraries of more traditional “small molecules” — are potentially available. What they need is a way to sort through them, a platform for screening thousands of drugs.

This is what Emory researchers report in a new Cell Chemical Biology paper. They also demonstrate that a class of drugs called IAP antagonists, one of which is already in clinical trials, can promote immune activity against cancer cells in their system.

Although checkpoint inhibitors are now FDA-approved for several types of cancer, many patients do not benefit from them. Finding drugs that loosen other parts of the immune response could increase efficacy, especially for types of cancer against which checkpoint inhibitors are ineffective by themselves.

Lead author Haian Fu, PhD, chair of the Department of Pharmacology and Chemical Biology at Emory University School of Medicine, says that drug discovery efforts in cancer immunotherapy have mostly focused on regulatory molecules on the outside of cells, which antibodies can easily reach.

“This is a robust co-culture system that enables high throughput screening for cancer immunotherapy,” Fu says. “There are many targets inside the cell. We want to shine a light on those intracellular targets.”

Working with Fu, instructor Xiulei Mo, PhD and colleagues created a system that can test whether compounds enhance the ability of human immune cells to suppress cancer cell growth. They call it HTiP, for “High-Throughput Immunomodulator Phenotypic Screening Platform.”

The HTiP system uses a mixture of human immune cells, combined with cancer cells carrying a known growth-driving mutation. The Emory researchers began with the well-known oncogene KRAS, and compared the effect of cancer cells (colon and lung cancer cell lines) with and without the KRAS mutation. The presence of the KRAS mutation was immunosuppressive, meaning that in the Emory system, the KRAS mutation provides resistance against immune cells killing the cancer cells.

Mo screened a library of about 2,000 known compounds, isolating the drug birinapant. It enhanced immune cell activity against the cancer cells, while doing little to the cancer cells on its own. Birinapant is part of a class of drugs called IAP antagonists, which are already being studied for anticancer activity.

“This was strong evidence for their relevance as immune enhancers,” Fu says. “It was a timely validation of our system.”

In fact, birinapant is being tested in combination with a checkpoint inhibitor. Two other IAP antagonists had similar effects in the same system, the researchers found.

The screening platform is agnostic to the mechanism of KRAS immunosuppression, or the precise type of immune cell. Fu notes that most checkpoint inhibitors appear to act on cytotoxic T cells, but the screening platform uses a combination of immune cell types.

“The effect in our system could come from any or all of those cell types,” he says. “Adaptive or innate response.”

All that is needed is for a compound to reverse the effect of the KRAS mutation. The system could be easily modified to test the effects of other oncogenic mutations, or to focus on one particular type of tumor antigen-specific immune cells, he says. The team also plans to expand its screening efforts, since 2,000 compounds is actually small, compared to the number of potential drugs.

Co-authors include Cong Tang, Qiankun Niu, PhD, Tingxuan Ma (an undergrad) and Yuhong Du, PhD

Du is associate professor of pharmacology and chemical biology at Emory University School of Medicine and associate director for assay development and high-throughput screening at the Emory Chemical Biology Discovery Center. Tang is a student in the Emory University — Xi’an Jiaotong University Health Science Center exchange program.

The research was supported by the National Cancer Institute (U01CA217875, U01CA199241, P30CA138292) the Georgia Cancer Coalition/Georgia Research Alliance and the Emory Chemical Biology Discovery Center.