Transformative awards for Mocarski's malleable cells, lung fibrosis

The National Institutes of Health has announced a five-year, $1.9 million Transformative Research Award to Emory virologist Edward Mocarski, PhD for his work on how the mechanisms of programmed cell death can be subverted. Mocarski is Robert W. Woodruff professor of microbiology and immunology at Emory University School of Medicine and Emory Vaccine Center. His research, which originated in probing how cells commit suicide when taken over by viruses, could lead to advances in regenerative medicine and organ transplant. The grant, funded through the National Institute of Allergy and Infectious Diseases, is one of nine “high-risk-, high-reward” Transformative Research Awards (13 recipients) announced by the NIH on October 6. In the same group this year, Thomas Barker in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University received a Transformative Research Award for his research on mechanosensors + pulmonary fibrosis. The Transformative Research Award program supports “exceptionally innovative, unconventional, paradigm-shifting research projects that are inherently risky and untested.” Emory has achieved only one other TRA since the program was established in 2009: Shuming Nie's project on imaging to guide cancer surgery. “This Transformative award was made possible because of the creative and engaged graduate students and postdoctoral fellows I have had working with me at Emory,” Mocarski says. In 2011, Mocarski, working with former graduate student William Kaiser and Emory geneticist Tamara Caspary showed that two complementary forms of programmed cell death, necrosis and apoptosis, can be genetically excised from mice, leaving a viable animal with a functioning immune system. These findings are yielding additional fruit. Mocarski’s research indicates that cells from these genetically altered mice are unexpectedly malleable, in that they are easier to reprogram into induced pluripotent stem cells. Once reprogrammed, induced pluripotent stem cells (iPS cells) can be directed to become cells of almost any tissue, making them promising potential tools for the treatment of many diseases. The genetically altered mice are also less susceptible to deadly inflammation and more readily accept bone marrow transplants. The Transformative project’s aims are to exploit these findings and test the ability of drugs that interfere with programmed cell death to facilitate tissue regeneration, iPS cell reprogramming and transplant.      

Cancer metastasis: isolating invasive cells with a color change

At Winship Cancer Institute, Adam Marcus and Jessica Konen have developed a tool for probing how invasive cells are different, which could lead to new ways to fight cancer metastasis. In the video, check out how they track the behavior of apparently devious "leader cells".

Tools for illuminating brain function make their own light

Hey optogenetics fans, cut (or temporarily put aside) the fiber optic cable. Flexible tools allow the choice between activation by light or an external chemical.


Adaptive mutation mechanism may drive some forms of antibiotic resistance

Evolutionary theory says mutations are blind and occur randomly. But in the controversial phenomenon of adaptive mutation, cells can peek under the blindfold, increasing their mutation rate in response to stress.

Scientists at Winship Cancer Institute, Emory University have observed that an apparent “back channel” for genetic information called retromutagenesis can encourage adaptive mutation to take place in bacteria.

The results were published Tuesday, August 25 in PLOS Genetics.

“This mechanism may explain how bacteria develop resistance to some types of antibiotics under selective pressure, as well as how mutations in cancer cells enable their growth or resistance to chemotherapy drugs,” says senior author Paul Doetsch, PhD.

Doetsch is professor of biochemistry, radiation oncology and hematology and medical oncology at Emory University School of Medicine and associate director of basic research at Winship Cancer Institute. The first author of the paper is Genetics and Molecular Biology graduate student Jordan Morreall, PhD, who defended his thesis in April.

Retromutagenesis resolves the puzzle: if cells aren’t growing because they’re under stress, which means their DNA isn’t being copied, how do the new mutants appear?

The answer: a mutation appears in the RNA first. Read more

Posted on by Quinn Eastman in Cancer, Uncategorized Leave a comment

Immune ‘traffic jam’ from viral infection

Several drugs now used to treat cancer and autoimmune diseases are actually repurposed tools derived from the immune system. One of the ways these “therapeutic antibodies” work is to grab onto malignant or inflammatory cells and escort them to their doom.

Emory researchers have found that in a mouse model of chronic viral infection, a kind of traffic pileup inside the body limits how effective therapeutic antibodies can be.

The results, published this week in Immunity, have implications for biotechnology researchers who continue to refine antibodies for therapeutic purposes, as well as bolster our understanding of how chronic viral infections impair the immune system.

Researchers led by Rafi Ahmed, PhD, director of the Emory Vaccine Center, were studying mice infected by LCMV (lymphocytic choriomeningitis virus). They injected several antibodies with the goal of removing various types of immune cells from the mice.  One end of the antibody molecule is supposed to bind the target cell, while another acts as a flag for other cells to get rid of the target cell.

However, during a chronic LCMV infection, the mouse’s immune system is producing its own antibodies against the virus, which form complexes with viral proteins. These immune complexes prevented the injected antibodies from having the effect the scientists wanted, which was to deplete their target cells.

Excessive amounts of immune complexes appear to be “clogging” the Fc gamma receptors that immune cells would use to grab the antibodies bound to the target cell, says postdoctoral fellow Andreas Wieland, PhD, first author of the Immunity paper. That these immune complexes form was not news; but how much they interfere with other antibodies was, Wieland says. Fc gamma receptors were already known to be important for antibodies to be effective against influenza and HIV. Read more

Posted on by Quinn Eastman in Immunology Leave a comment

Cancer’s shield: PD-1

Gina Kolata has a section front story in Tuesday’s New York Times exploring the potential of a relatively new class of anticancer drugs. The drugs break through “shields” built by cancers to ward off the threat posed by the patient’s immune system. Many are based on blocking PD-1, an immune regulatory molecule whose importance in chronic infections was first defined by Emory’s Rafi Ahmed.

Of course, not every cancer research development described as transformative in the New York Times lives up to the hype. But the clinical trial results, reported in the New England Journal of Medicine, are solid enough that the researchers Kolata talks with think they are seeing “a moment in medical history when everything changed.” [Winship Cancer Institute’s John Kauh was a co-author on one of the 2012 NEJM papers.]

Let’s take a moment to examine some of the roots of this story. Rafi Ahmed didn’t set out to study cancer. For the last two decades, he and his colleagues have been studying T cells, parts of the immune system that are critical for responding to infections. Read more

Posted on by Quinn Eastman in Cancer, Immunology 2 Comments

The challenges of graduate school

Biochemist Paul Doetsch’s recent appearance in a Science magazine feature on laboratory leadership led to a conversation with him about the challenges of graduate school.

He emphasized that scientific research is a team sport, and brilliance on the part of the lab head may not yield fruit without a productive relationship with the people in the lab. Doetsch suggested talking with Lydia Morris, a graduate student in the Genetics and Molecular Biology graduate program. Morris has been working in Doetsch’s lab for several years and is about to complete her degree. She has been examining the in vivo distribution of DNA repair proteins.

In this video, Morris and Doetsch talk about the differences between turn-the-crank and blue-sky projects, and the importance of backup projects, communications, high expectations and perseverance.

Posted on by Quinn Eastman in Cancer Leave a comment

The body’s anticancer defenses come in a variety of sizes

Sometimes you have to look at the whole picture, big and small.

Sarah Cork, PhD

That was the lesson that emerged from Winship Cancer Institute researcher Erwin Van Meir’s laboratory, highlighted in a recent paper in Oncogene. Van Meir’s team has been studying vasculostatin, a secreted protein that inhibits blood vessel growth by tumors (hence the name). Vasculostatin was discovered by Balveen Kaur, now at Ohio State, while she was in Van Meir’s lab.

Van Meir and his colleagues originally began studying vasculostatin because it is a product of a gene that brain tumors somehow silence or get rid of, and studying the obstacles our bodies throws in cancer’s way may be a good way to learn how to fight it via modern medicine. Eventually, it could form the basis for a treatment to prevent a tumor from attracting new blood vessels.

Vasculostatin is somewhat unique because it is a secreted fragment of a membrane-bound protein, called BAI1. BAI1 has an apparently separate function as an “engulfment receptor,” allowing the recognition and internalization of dying cells.

Most of the secreted vasculostatin is around 40 kilodaltons in size, not 120 as previously thought.

Graduate student Sarah Cork discovered that most of the vasculostatin protein being produced by cells is actually much smaller than what had been originally discovered. She and Van Meir were surprised to find that the smaller, cleaved form of the protein still has potent anti-angiogenic activity.

The researchers were using a technique where a mixture of proteins is separated within a gel by electric current, transferred to a polymer sheet, and probed with antibodies. The large proteins appear at the top and the small proteins at the bottom.

“Previously, we had been running the gels for a long time to detect large protein fragments, so missed out on what was happening with small fragments which run off the gel,” Van Meir says. “We were only looking at the top of the
gel, when the smaller form of vasculostatin was actually much more
abundant as you can see on the picture of a gel run for a shorter time.”

More broadly, Van Meir says that the finding adds to understanding about BAI1’s dual function in the brain and how vasculostatin (big or small) might be used in anticancer therapy.

Posted on by Quinn Eastman in Cancer Leave a comment

Dye me anticancer yellow

Over the last few years, pathologist Keqiang Ye and his colleagues have displayed an uncanny talent for finding potentially useful medicinal compounds. Recently another example of this talent appeared in Journal of Biological Chemistry.

Keqiang Ye, PhD

Postdoctoral fellow Qi Qi is first author on the paper. Collaborators include Jeffrey Olson, Liya Wang, Hui Mao, Haian Fu, Suresh Ramalingam and Shi-Yong Sun at Emory and Paul Mischel at UCLA.

Qi and Ye were looking for compounds that could inhibit the growth of an especially aggressive form of brain cancer, glioblastoma with deletion in the tumor suppressor gene PTEN. Tumors with this deletion do not respond to currently available targeted therapies.

The researchers found that acridine yellow G, a fluorescent dye used to stain microscope slides, can inhibit the growth of this tumor:

Oral administration of this compound evidently decreases the tumor volumes in both subcutaneous and intracranial models and elongates the life span of brain tumor inoculated nude mice. It also displays potent antitumor effect against human lung cancers. Moreover, it significantly decreases cell proliferation and enhances apoptosis in tumors…

Optimization of this compound by improving its potency through medicinal chemistry modification might warrant a novel anticancer drug for malignant human cancers.

Ye’s team observed that acridine yellow G appears not to be toxic in rodents. However, the acridine family of compounds tends to intercalate (insert itself) into DNA and can promote DNA damage, so more toxicology studies are needed. Other acridine family compounds such as quinacrine have been used to treat bacterial infections and as antiinflammatory agents, they note.

A paramecium stained with acridine orange, which shows anticancer activity for tumors containing PTEN mutations

Posted on by Quinn Eastman in Cancer Leave a comment

A twist on epigenetic therapy vs cancer

Epigenetic therapies against cancer have attracted considerable attention in recent years. But many of the drugs currently being studied as epigenetic anticancer therapies may have indiscriminate effects. A recent paper in Cancer Research from brain cancer researcher Erwin Van Meir’s laboratory highlights a different type of target within cancer cells that may be more selective. Postdoctoral fellow Dan Zhu is the first author of the paper.

Erwin Van Meir, PhD

The basic idea for epigenetic therapy is to focus on how cancer cells’ DNA is wrapped instead of the mutations in the DNA. Cancer cells often have aberrant patterns of methylation or chromatin modifications. Methylation is a punctuation-like modification of DNA that usually shuts genes off, and chromatin is the term describing DNA when it is clothed by proteins such as histones, a form of packaging that determines whether a gene is on or off.

In contrast to mutations that are hard-wired in the DNA, changes in cancer cells’ methylation or chromatin may be reversible with certain drug treatments. But a puzzle remains: if a drug wipes away methylation indiscriminately, that might turn on an oncogene just as much as it might restore a tumor suppressor gene.

The ability of an inhibitor of methylation to treat cancer may depend on cell type and context, explains chromatin/methylation expert and co-author Paula Vertino. She points out that one well-known methylation inhibitor, azacytidine (Vidaza), is a standard treatment for myelodysplastic syndrome, but the strategy of blanket-inhibition of methylation can’t be expected to work for all cancers. A similar challenge exists for agents that target histone acetylation in a global fashion.

Epigenetic therapies seek to modify how DNA is packaged in the cell.

Van Meir’s laboratory has been studying a tumor suppressor protein called BAI1 (brain angiogenesis inhibitor 1), which prevents tumor and blood vessel growth. BAI1 is produced by brain cells naturally, but is often silenced epigenetically in glioblastoma cells. His team found that azacytidine de-represses the BAI1 gene.

Methylation won’t turn a gene off without the help of a set of proteins that bind preferentially to methylated DNA. These proteins are what recognize the methylation state of a given gene and recruit repressive chromatin. Zhu and colleagues in Van Meir’s group found that one particular methyl-binding protein, MBD2, is overproduced in glioblastoma and is enriched on the BAI1 gene.

“Taken together, our results suggest that MBD2 overexpression during gliomagenesis may drive tumor growth by suppressing the anti-angiogenic activity of a key tumor suppressor. These findings have therapeutic implications since inhibiting MBD2 could offer a strategy to reactivate BAI1 and suppress glioma pathobiology,” the authors write.

By itself, MBD2 appears to be dispensable, since mice seem to be able to develop and survive without it. Not having it even seems to push back against tumor formation in the intestine, for example. Targeting MBD2 may represent an alternative way to steer away from cancer cells’ altered state.

Van Meir cautions: “We need to have a better understanding of all the genes that are turned on or off by silencing MBD2 in a given cancer before we can envision to use this approach for therapy.”

Vertino and Steven Hunter, both at Emory, are co-authors on the paper. The work was supported by grants from the NIH and the Southeastern Brain Tumor Foundation and the Emory University Research Council.

Posted on by Quinn Eastman in Cancer 1 Comment

Esophageal lesions meet their match

Field Willingham, MD, MPH

Once esophageal tumors establish themselves, a patient’s prognosis is grim and morbidity vast. But when lesions are caught early and removed, especially in the premalignant stage, the odds of survival markedly improve.

When a case calls for it, Emory gastroenterologist Field F. Willingham, MD, MPH, uses a hybrid approach to ousting superficial esophageal lesions. Superficial esophageal lesions are commonly caused by acid reflux disease, or GERD. GERD occurs when stomach acid flows into the esophagus and can lead to a condition known as Barrett’s esophagus, where the cells in the lower esophagus become damaged. This in turn can lead to dysplasia, or pre-cancerous cells.

But for superficial cancers, it is now possible to remove a portion of the lining layer of the GI tract, containing the tumor, with an endoscope.  This can help carefully selected patients avoid a major surgery. The technique, known as an EMR, allows the removal of superficial esophageal tumors and pre-cancer with an endoscope, a slender tube-like instrument.

Detecting and removing esophageal tumors early is essential for a favorable outcome. Once tumors firmly establish themselves in esophageal tissue, the prognosis is grim and morbidity vast. In the past, a diagnosis of an esophageal tumor meant the removal of the esophagus and often the stomach. But now EMR can be used in tandem with radio frequency ablation.

In surgical situations in which radio frequency ablation is not feasible, Willingham and his colleagues are beginning to use an alternate technique, known as cryotherpay, in tandem with EMR. Cryotherapy involves freezing superficial cells to rid the esophagus of suspect cells.

“So, if the end of the esophagus is twisted, or if we can’t touch it with this balloon device, then we can use cryotherapy,” says Willingham. “We’re trying to kill the lining layer with the tumor cells without killing the deeper layer.”

Willingham and his colleagues are seeing evidence that using these very three very different, technologies in tandem or alone will provide patients with a better way to rid them of esophageal lesions while preserving their quality of life.

Posted on by Robin Tricoles in Uncategorized Leave a comment

Genetic alteration opens door to targeted treatment of rare tumor

A cross section of an epithelioid hemangioendothelioma

Emory pathologist Sharon Weiss, MD, was the first to describe an extraordinarily rare tumor known as an epithelioid hemangioendothelioma (EHE). Thirty years later, researchers have identified a genetic alteration linked to this odd vascular tumor.

It’s hoped this newfound information will lead to a better understanding of the mechanisms underlying the development of this tumor and hence development of a targeted treatment. None yet is available. However, these findings already have been used to develop a new diagnostic test for this blood vessel disease.

The research, published in a recent issue of Science Translational Medicine, was done in collaboration with Cleveland Clinic’s Taussig Cancer Institute and led by Brian Rubin, MD, PhD, of Cleveland Clinic’s Pathology and Laboratory Medicine Institute and Lerner Research Institute.

The genetic alteration formerly in question involves a translocation between chromosomes 1 and 3, where chromosomes 1 and 3 exchange DNA fragments that are transposed onto opposite chromosomes. The result: the swapped DNA encodes a unique, fused gene that contains components from each chromosome. Because genes are translated into proteins, the result of this unique gene is a correspondingly unique protein, one thought to cause cancer.

Epithelioid hemangioendotheliomas comprise less than one percent of all cancers. Roughly 100 new cases are diagnosed in the United State each year. EHE are eccentric in their epidemiology, structure and aggressiveness. Slow to metastasize, they tend to occur in both young men and women when soft tissue is involved but occur mostly in women when the liver and lungs are affected.

However, it’s their peculiar structure that has so far made targeted treatment problematic, especially in the liver and lungs. “Instead of being one mass as you might expect with liver cancer, the patient with EHE often presents with little nodules throughout the liver,” says Weiss.

“The reason this occurs is that the growth starts in the liver’s portal vein, grows along its length, and then tracks out through the vessels. The growths blister out from the vessel creating these little nodules. Epithelioid hemangioendothelioma don’t possess the classic features of vascular tumors. In fact, EHE may have so many sites of involvement that the cancer can’t be cured, short of transplantation.”

Using EHE tissue samples gleaned from Weiss’s vast library, Rubin developed a genetic probe to detect the distinct chromosomal translocations in the tumor. The probe now serves as a powerful diagnostic tool of EHE and opens the door to understanding these tumors’ mechanisms.

“Once you understand the mechanism behind it, you can start trying to target those pathways in a therapeutic way,” says Weiss.

Posted on by Robin Tricoles in Cancer 1 Comment

Magnanimous magnolias keep on giving

Honokiol, the versatile compound found by Emory dermatologist Jack Arbiser in the cones of magnolia trees, makes a surprise appearance in a recent paper in Nature Medicine.

Jack Arbiser, MD, PhD, and colleagues originally isolated honokiol from magnolia cones. It can also be found in herbal teas.

The paper, from Sabrina Diano, Tamas Horvath and colleagues at Yale, probes the role of reactive oxygen species (ROS) in the hypothalamus, a part of the brain that regulates appetite. In the paper, Horvath’s laboratory uses honokiol as a super-antioxidant, mopping up ROS that suppress appetite. Arbiser initiated the collaboration with Horvath after finding, while working with Emory free radical expert Sergei Dikalov, how effective honokiol is at neutralizing ROS.

The paper is intriguing partly because it’s an example of a situation where ROS, often thought to be harmful because of their links to aging and several diseases, are actually beneficial. In this case, they provide a signal to stop eating. A recent paper from Andrew Neish’s lab at Emory provides another example, where probiotic bacteria stimulate production of ROS, which promote healing of the intestine.

Arbiser notes that since honokiol can increase appetite, the compound may be helpful in situations where doctors want patients to eat more.

“This might be particularly valuable in patients who are nutritionally deficient due to chemotherapy and provides a rationale for adding honokiol to chemotherapy regimens,” he writes.

Satiety producing neurons in the hypothalamus

A note of caution: in the Nature Medicine paper, honokiol is infused directly into the brain.

Honokiol has been shown to counteract inflammation and slow the growth of blood vessels (important in fighting cancer). Collaborating with Arbiser, Emory endocrinologist Neale Weitzmann has recently found that honokiol stimulates osteoblasts, the cells that build bone, suggesting that it could reduce bone loss in osteoporosis.

Posted on by Quinn Eastman in Cancer Leave a comment
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