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Espaço de publicação e discussão sobre oncologia. GBM IMMUNOTHERAPY ONCO-VIRUS ONCOLOGY CANCER CHEMOTHERAPY RADIOTHERAPY


Quinta-feira, 23.07.15

Researchers find easy way to produce carbon nanoparticles that can carry drugs to targeted tissues

 

Researchers find easy way to produce carbon nanoparticles that can carry drugs to targeted tissues

Published on June 19, 2015 at 3:57 AM ·

Researchers have found an easy way to produce carbon nanoparticles that are small enough to evade the body's immune system, reflect light in the near-infrared range for easy detection, and carry payloads of pharmaceutical drugs to targeted tissues.

Unlike other methods of making carbon nanoparticles - which require expensive equipment and purification processes that can take days - the new approach generates the particles in a few hours and uses only a handful of ingredients, including store-bought molasses.

The researchers, led by University of Illinois bioengineering professors Dipanjan Pan and Rohit Bhargava, report their findings in the journal Small.

"If you have a microwave and honey or molasses, you can pretty much make these particles at home," Pan said. "You just mix them together and cook it for a few minutes, and you get something that looks like char, but that is nanoparticles with high luminescence. This is one of the simplest systems that we can think of. It is safe and highly scalable for eventual clinical use."

These "next-generation" carbon spheres have several attractive properties, the researchers found. They naturally scatter light in a manner that makes them easy to differentiate from human tissues, eliminating the need for added dyes or fluorescing molecules to help detect them in the body.

The nanoparticles are coated with polymers that fine-tune their optical properties and their rate of degradation in the body. The polymers can be loaded with drugs that are gradually released.

The nanoparticles also can be made quite small, less than eight nanometers in diameter (a human hair is 80,000 to 100,000 nanometers thick).

"Our immune system fails to recognize anything under 10 nanometers," Pan said. "So, these tiny particles are kind of camouflaged, I would say; they are hiding from the human immune system."

The team tested the therapeutic potential of the nanoparticles by loading them with an anti-melanoma drug and mixing them in a topical solution that was applied to pig skin.

Bhargava's laboratory used vibrational spectroscopic techniques to identify the molecular structure of the nanoparticles and their cargo.

"Raman and infrared spectroscopy are the two tools that one uses to see molecular structure," Bhargava said. "We think we coated this particle with a specific polymer and with specific drug-loading - but did we really? We use spectroscopy to confirm the formulation as well as visualize the delivery of the particles and drug molecules."

The team found that the nanoparticles did not release the drug payload at room temperature, but at body temperature began to release the anti-cancer drug. The researchers also determined which topical applications penetrated the skin to a desired depth.

In further experiments, the researchers found they could alter the infusion of the particles into melanoma cells by adjusting the polymer coatings. Imaging confirmed that the infused cells began to swell, a sign of impending cell death.

"This is a versatile platform to carry a multitude of drugs - for melanoma, for other kinds of cancers and for other diseases," Bhargava said. "You can coat it with different polymers to give it a different optical response. You can load it with two drugs, or three, or four, so you can do multidrug therapy with the same particles."

"By using defined surface chemistry, we can change the properties of these particles," Pan said. "We can make them glow at a certain wavelength and also we can tune them to release the drugs in the presence of the cellular environment. That is, I think, the beauty of the work."

Source:

University of Illinois at Urbana-Champaign

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por cyto às 22:55

Terça-feira, 21.07.15

TSRI study reveals alternative approach to current anti-HIV strategies

 

TSRI study reveals alternative approach to current anti-HIV strategies

Published on July 9, 2015 at 8:49 AM 

AIDS Study Points to ‘Functional Cure’

HIV-infected patients remain on antiretroviral therapy for life because the virus survives over the long-term in infected dormant cells. Interruption of current types of antiretroviral therapy results in a rebound of the virus and clinical progression to AIDS.

But now, scientists from the Florida campus of The Scripps Research Institute (TSRI) have shown that, unlike other antiretroviral therapies, a natural compound called Cortistatin A reduces residual levels of virus from these infected dormant cells, establishing a near-permanent state of latency and greatly diminishing the virus' capacity for reactivation.

"Our results highlight an alternative approach to current anti-HIV strategies," said Susana Valente, a TSRI associate professor who led the study. "Prior treatment with Cortistatin A significantly inhibits and delays viral rebound in the absence of any drug. Our results suggest current antiretroviral regimens could be supplemented with a Tat inhibitor such as Cortistatin A to achieve a functional HIV-1 cure, reducing levels of the virus and preventing reactivation from latent reservoirs."

The study was published this week in the journal mBio.

Cortistatin A was isolated from a marine sponge, Corticium simplex, in 2006, and in 2008, TSRI chemist Phil Baran won the global race to synthesize the compound. A configuration of the compound, didehydro-Cortistatin A, was shown in earlier studies to target the protein Tat, which exponentially increases viral production.

The new study shows that didehydro-Cortistatin A inhibits replication in HIV-infected cells by significantly reducing levels of viral messenger RNA - the blueprints for producing proteins and more infection.

"In latently infected primary T cells isolated from nine HIV-infected subjects being treated with antiretroviral drugs, didehydro-Cortistatin A reduced viral reactivation by an average of 92.3 percent," said Guillaume Mousseau, the first author of the study and a member of the Valente lab.

The results suggest an alternative to a widely studied strategy for latent HIV eradication known as "kick and kill," which tries to purge viral reservoirs by "kicking" them out of their latency with reversing agents and stopping new rounds of infection with an immunotherapy agent to boost the body's own immune system response while on antiretroviral treatment.

"In our proposed model, didehydro-Cortistatin A inhibits the viral transcriptional activator, Tat, far more completely, delaying or even halting viral replication, reactivation and replenishment of the latent viral reservoir," said Valente.

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por cyto às 18:25

Terça-feira, 21.07.15

Novel cancer drug candidate developed in Singapore advances into clinical trials

 

Novel cancer drug candidate developed in Singapore advances into clinical trials

Published on July 17, 2015 at 2:01 AM

A made-in-Singapore cancer drug has advanced into clinical trials, charting a milestone in Singapore's biomedical sciences initiative that will go towards improving the lives of cancer patients in Singapore, and worldwide. The Agency for Science, Technology and Research (A*STAR) and Duke-National University of Singapore Graduate Medical School (Duke-NUS) today announced the start of a Phase I clinical trial of novel cancer drug candidate, ETC-159. This is the first publicly-funded drug candidate discovered and developed in Singapore to advance into first-in-human trials, and will target a range of cancers. Overall, cancer is the leading cause of death in Singapore, accounting for 30 percent of deaths in 2013. Cancer has also resulted in 8.2 million deaths world-wide .

ETC-159 targets a number of cancers including colorectal, ovarian and pancreatic cancers which contribute to a significant proportion of Singapore's cancer burden. These cancers are linked to a group of cell signalling pathways known as Wnt signalling, that have been identified to promote cancer growth and spread when elevated or dysregulated. As ETC-159 is an inhibitor of these pathways, it could suppress cancer proliferation and prevent cancer progression.

This drug candidate therefore offers a promising novel and targeted cancer therapy that could shape future cancer therapeutic strategies.

ETC-159 was discovered and developed through a collaboration between A*STAR's Experimental Therapeutics Centre (ETC), Drug Discovery and Development (D3) unit and Duke-NUS since 2009. This was based on the discovery work of Prof David Virshup from Duke-NUS, who has continued to contribute to the development of the drug candidate.

The Phase I clinical trial will evaluate the safety and tolerability of ETC-159 in advanced solid tumours of up to 58 patients. The first patient was dosed on 18 June 2015.

Dr Benjamin Seet, Executive Director of A*STAR's Biomedical Research Council, said, "This breakthrough, which closely follows local company MerLion Pharmaceuticals' recent success in obtaining FDA approval for one of its drugs, marks an inflection point in Singapore's biomedical sciences initiative. Despite the protracted process of drug discovery and development, I am confident that we will see more locally developed drugs in the pipeline being tested and implemented."

Prof Ranga Rama Krishnan, Chairman of the National Medical Research Council (NMRC), Singapore, said, "The first dosing of a drug developed by A*STAR based on a scientific discovery by Duke-NUS researchers, is an example of the terrific and exciting progress that has been made when different entities come together to work on a common problem. This will lead to developing new treatments that can benefit patients in Singapore and beyond."

Prof Alex Matter, Chief Executive Officer of ETC and D3 said, "The discovery and subsequent development of this drug candidate marks a major breakthrough in cancer therapeutics. It also demonstrates the world-class drug discovery and development capabilities we have built up at ETC and D3, complemented by valued partners like Duke-NUS. We will continue to strengthen these capabilities and partnerships to continue developing a pipeline of promising drug candidates and advancing them into the clinic."

Prof David Virshup, inaugural Director of the Programme in Cancer and Stem Cell Biology at Duke-NUS, said, "As the drug candidate provides a targeted cancer therapy, it could potentially minimise side effects and make cancer treatments more bearable for cancer patients. This is a major milestone that was made possible by Singapore's ongoing investment in basic and translational biomedical research to address unmet medical needs. It is fitting that Singaporeans might be the first to benefit from this Singapore-developed drug."

A*STAR's ETC and Duke-NUS are the primary drivers of the discovery and development of the drug candidate. D3 joined the collaboration in 2013 to bring the project forward to achieve proof of concept in humans.

D3 has obtained ethics and regulatory approval for this trial from the SingHealth Centralised Institutional Review Board (CIRB) and the Singapore Health Sciences Authority (HSA) respectively. The first two sites for the trial are the National Cancer Centre Singapore (NCCS) and the National University Hospital (NUH), Singapore. Trial sites in the United States will be opened as the trial progresses.

Source:

Biomedical Sciences Institutes (BMSI)

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por cyto às 18:15

Terça-feira, 21.07.15

Ludwig, CRI launch clinical trials to evaluate immunotherapies for treatment of GBM and solid tumors

 

Ludwig, CRI launch clinical trials to evaluate immunotherapies for treatment of GBM and solid tumors

Published on July 8, 2015 at 11:50 PM 

Ludwig Cancer Research (Ludwig) and the Cancer Research Institute (CRI) have launched clinical trials evaluating an immunotherapy for the treatment of the brain cancer glioblastoma multiforme (GBM), and a combination of immunotherapies for a variety of solid tumors.

The trials are being conducted through the CVC Clinical Trials Network in collaboration with MedImmune, the global biologics research and development arm of AstraZeneca. The CVC Clinical Trials Network -- jointly managed by Ludwig and CRI -- is a coordinated global network of basic and clinical immunologists with expertise in devising and developing immunotherapies for the treatment of cancer. The CVC Clinical Trials Network is led by Jedd Wolchok, Ludwig member and director of the Ludwig Collaborative Laboratory at Memorial Sloan Kettering Cancer Center, as well as associate director of the CRI Scientific Advisory Council.

The GBM trial is a nonrandomized, multicenter Phase 2 trial testing the effects of MedImmune's checkpoint blockade antibody durvalumab (MEDI4736) in patients with GBM, which is the most aggressive and deadly type of adult brain cancer. The study will be conducted using three cohorts of patients - newly diagnosed, recurrent patients and those with tumors which have become unresponsive to standard treatment of care.

"GBM is an inevitably lethal cancer that has so far eluded every therapy in the pharmaceutical arsenal," said Jonathan Skipper, Ludwig's executive director of technology development. "We are hopeful that adding a promising immunotherapy to the treatment regimen for this brain cancer will yield significant benefits for patients who today have a median life expectancy of roughly 15 months, even with the best treatment available."

Durvalumab is an investigational human monoclonal antibody directed against programmed cell death ligand 1 (PD-L1). Signals from PD-L1 help tumors avoid detection by the immune system. Durvalumab blocks these signals, countering the tumor's immune-evading tactics. The antibody belongs to an emerging class of immunotherapies commonly referred to as checkpoint inhibitors because they remove checks the body places on immune activation.

"Checkpoint inhibitors have deservedly stirred considerable excitement in the oncology community as their application yields notable results against a growing variety of cancers," said Adam Kolom, managing director of CRI's venture fund and Clinical Accelerator, which organizes and provides philanthropic funding and clinical resources for this and other promising immunotherapy trials. "This will be the first time the immunotherapeutic agent will be tested against this difficult-to-treat cancer, and its outcomes are eagerly anticipated by the GBM patient community."

The other trial, which Ludwig and CRI launched in 2013, is a Phase 1 nonrandomized multicenter trial evaluating the combination of durvalumab with another checkpoint blockade therapy (tremelimumab, anti-CTLA-4) for the treatment of a variety of advanced solid tumors including ovarian cancer, non-small cell lung cancer, colorectal cancer, head and neck cancer, cervical cancer and kidney cancer.

Both clinical trials, which are now under way, are part of a larger clinical research program supported by Ludwig and CRI to speed the evaluation of novel cancer immunotherapies, alone or in combination with other cancer drugs. All of the studies will include collection of genetic and immunologic data derived from clinical samples obtained from patients. Such information will provide clues to the impact of the evaluated therapies and suggest refined or new strategies for treating cancer.

Source:

Ludwig Institute for Cancer Research

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por cyto às 18:12

Terça-feira, 21.07.15

Single molecule appears to be central regulator driving cancer metastasis

 

Single molecule appears to be central regulator driving cancer metastasis

Published on July 14, 2015 at 6:21 AM · 

Cancer is a disease of cell growth, but most tumors only become lethal once they metastasize or spread from their first location to sites throughout the body. For the first time, researchers at Thomas Jefferson University in Philadelphia report a single molecule that appears to be the central regulator driving metastasis in prostate cancer. The study, published online July 13th in Cancer Cell, offers a target for the development of a drug that could prevent metastasis in prostate cancer, and possibly other cancers as well.

"Finding a way to halt or prevent cancer metastasis has proven elusive. We discovered that a molecule called DNA-PKcs could give us a means of knocking out major pathways that control metastasis before it begins," says Karen Knudsen, Ph.D., Director of the Sidney Kimmel Cancer Center at Thomas Jefferson University, the Hilary Koprowski Professor and Chair of Cancer Biology, Professor of Urology, Radiation Oncology, and Medical Oncology at Jefferson.

Metastasis is thought of as the last stage of cancer. The tumor undergoes a number of changes to its DNA - mutations - that make the cells more mobile, able to enter the bloodstream, and then also sticky enough to anchor down in a new location, such as the bone, the lungs, the liver or other organs, where new tumors start to grow. Although these processes are fairly well characterized, there appeared to be many non-overlapping pathways that ultimately lead to these traits.

Now, Dr. Knudsen and colleagues have shown that one molecule appears to be central to many of the processes required for a cancer to spread. That molecule is a DNA repair kinase called DNA-PKcs. The kinase rejoins broken or mutated DNA strands in a cancer cell, acting as a glue to the many broken pieces of DNA and keeping alive a cell that should normally self-destruct. In fact, previous studies had shown that DNA-PKcs was linked to treatment resistance in prostate cancer, in part because it would repair the usually lethal damage to tumors caused by radiation therapy and other treatments. Importantly, Dr. Knudsen's work showed that DNA-PKcs has other, far-reaching roles in cancer.

The researchers showed that DNA-PKcs also appears act as a master regulator of signaling networks that turn on the entire program of metastatic processes. Specifically, the DNA-PKcs modulates the Rho/Rac enzyme, which allows many cancer cell types to become mobile, as well as a number of other gene networks involved in other steps in the metastatic cascade, such as cell migration and invasion.

In addition to experiments in prostate cancer cell lines, Dr. Knudsen and colleagues also showed that in mice carrying human models of prostate cancer, they could block the development of metastases by using agents that suppress DNA-PKcs production or function. And in mice with aggressive human tumors, an inhibitor of DNA-PKcs reduced overall tumor burden in metastatic sites.

In a final analysis that demonstrated the importance of DNA-PKcs in human disease, the researchers analyzed 232 samples from prostate cancer patients for the amount of DNA-PKcs those cells contained and compared those levels to the patients' medical records. They saw that a spike in the kinase levels was a strong predictor of developing metastases and poor outcomes in prostate cancer. They also showed that DNA-PKcs was much more active in human samples of castrate-resistant prostate cancer, an aggressive and treatment-resistant form of the disease.

"These results strongly suggest that DNA-PKcs is a master regulator of the pathways and signals that lead to the development of metastases in prostate cancer, and that high levels of DNA-PKcs could predict which early stage tumors may go on to metastasize," says Dr. Knudsen.

"The finding that DNA-PKcs is a likely driver of lethal disease states was unexpected, and the discovery was made possible by key collaborations across academia and industry," explains Dr. Knudsen. Key collaborators on the study, in addition to leaders of the Sidney Kimmel Cancer Center's Prostate Program, included the laboratories of Felix Feng (University of Michigan), Scott Tomlins (University of Michigan), Owen Witte (UCLA), Cory Abate-Shen (Columbia University), Nima Sharifi (Cleveland Clinic) and Jeffrey Karnes (Mayo Clinic), and contributions from GenomeDx.

Although not all molecules are easily turned into drugs, at least one pharma company has already developed a drug that inhibits DNA-PKcs, and is currently testing it in a phase 1 study (NCT01353625). "We are enthusiastic about the next step of clinical assessment for testing DNA-PKcs inhibitors in the clinic. A new trial will commence shortly using the Celgene CC-115 DNA-PKcs inhibitor. This new trial will be for patients advancing on standard of care therapies, and will be available at multiple centers connected through the Prostate Cancer Clinical Trials Consortium, of which we are a member," explained Dr. Knudsen.

"Although the pathway to drug approval can take many years, this new trial will provide some insight into the effect of DNAP-PKcs inhibitors as anti-tumor agents. In parallel, using this kinase as a marker of severe disease may also help identify patients whose tumors will develop into aggressive metastatic disease, so that we can treat them with more aggressive therapy earlier," says Dr. Knudsen. "Given the role of DNA-PKcs in DNA repair as well as control of tumor metastasis, there will be challenges in clinical implementation, but this discovery unveils new opportunities for preventing or treating advanced disease."

Source:

Thomas Jefferson University

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por cyto às 18:05

Sábado, 04.07.15

gene mutation linked to anaplastic oligodendroglioma

Scientists identify gene mutation linked to anaplastic oligodendroglioma

Published on June 12, 2015 at 9:23 AM · 

Scientists have identified a gene mutation linked to the development of an aggressive form of brain cancer.

Researchers found that errors in a gene known as TCF12 - which plays a key role in the formation of the embryonic brain are associated with more aggressive forms of a disease called anaplastic oligodendroglioma.

The new research is the largest ever genetic study of oligodendrogliomas, and provides important insights into their causes - and how they might be treated.

Oligodendrogliomas are fast-growing cancers that account for around 5-10 per cent of all tumours of the brain and central nervous system, and typically have a very poor prognosis.

Researchers at The Institute of Cancer Research, London, in collaboration with laboratories in France and Canada, compared the genetic sequence of 134 of these brain tumours with the DNA of healthy cells.

The study was largely funded by Investissements d'avenir and Génome Québec, with support from Cancer Research UK, and was published in the journal Nature Communications.

Researchers identified mutations in the TCF12 gene in 7.5 per cent of anaplastic oligodendrogliomas. They found that this subset of cancers grew more rapidly, and in other ways seemed more aggressive, than those where the gene was intact.

TCF12 is the genetic code for a protein that binds to DNA and controls the activity of other genes. The researchers found that mutations in TCF12 rendered the protein less able to bind to DNA, and this in turn led to a reduction in activity of other key genes - including one already associated with cancer spread, known as CHD1.

The researchers initially read the DNA sequence of 51 tumours and went on to look for TCF12 mutations in an additional group of 83.

The researchers also discovered errors in the gene IDH1 in 78 per cent of the tumours, confirming the findings of an initial scan of the data.

Finding out more about what genetic faults cause anaplastic oligodendrogliomas will allow scientists and clinicians to develop new personalised therapies that target a range of the mutations driving the disease.

Professor Richard Houlston, Professor of Molecular and Population Genetics at The Institute of Cancer Research, London, said:

"Our in-depth study has set out many of the genetic defects that cause this rare but highly aggressive form of brain cancer - including identifying a gene mutation that appears in particularly fast-growing forms.

"Anaplastic oligodendrogliomas are difficult to remove by surgery and don't respond well to other forms of treatment. We hope this new information might be used to discover new targeted therapies, offering patients a better chance at survival from this aggressive cancer."

Source:

Institute of Cancer Research

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por cyto às 11:46

Sábado, 04.07.15

Fibromyalgia now considered as a lifelong central nervous system disorder

Fibromyalgia now considered as a lifelong central nervous system disorder

Published on May 18, 2015 at 6:10 AM ·

Fibromyalgia is the second most common rheumatic disorder behind osteoarthritis and, though still widely misunderstood, is now considered to be a lifelong central nervous system disorder, which is responsible for amplified pain that shoots through the body in those who suffer from it. Daniel Clauw, M.D., professor of anesthesiology, University of Michigan, analyzed the neurological basis for fibromyalgia in a plenary session address today at the American Pain Society Annual Scientific Meeting.

"Fibromyalgia can be thought of both as a discreet disease and also as a final common pathway of pain centralization and chronification. Most people with this condition have lifelong histories of chronic pain throughout their bodies," said Clauw. "The condition can be hard to diagnose if one isn't familiar with classic symptoms because there isn't a single cause and no outward signs."

Clauw explained that fibromyalgia pain comes more from the brain and spinal cord than from areas of the body in which someone may experience peripheral pain. The condition is believed to be associated with disturbances in how the brain processes pain and other sensory information. He said physicians should suspect fibromyalgia in patients with multifocal (mostly musculoskeletal) pain that is not fully explained by injury or inflammation.

"Because pain pathways throughout the body are amplified in fibromyalgia patients, pain can occur anywhere, so chronic headaches, visceral pain and sensory hyper-responsiveness are common in people with this painful condition," said Clauw.

"This does not imply that peripheral nociceptive input does not contribute to pain experienced by fibromyalgia patients, but they do feel more pain than normally would be expected from the degree of peripheral input. Persons with fibromyalgia and other pain states characterized by sensitization will experience pain from what those without the condition would describe as touch," Clauw added.

Due to the central nervous system origins of fibromyalgia pain, Clauw said treatments with opioids or other narcotic analgesics usually are not effective because they do not reduce the activity of neurotransmitters in the brain. "These drugs have never been shown to be effective in fibromyalgia patients, and there is evidence that opioids might even worsen fibromyalgia and other centralized pain states," he said.

Clauw advises clinicians to integrate pharmacological treatments, such as gabapentinoids, trycyclics and serotonoin reuptake inhibitors, with nonpharmacological approaches like cognitive behavioral therapy, exercise and stress reduction.

"Sometimes the magnitude of treatment response for simple and inexpensive non-drug therapies exceeds that for pharmaceuticals," said Clauw. "The greatest benefit is improved function, which should be the main treatment goal for any chronic pain condition. The majority of patients with fibromyalgia can see improvement in their symptoms and lead normal lives with the right medications and extensive use of non-drug therapies."

Source:

American Pain Society (APS)

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por cyto às 11:40

Sábado, 04.07.15

Harvard Medical School scientists reveal structure of vesicular stomatitis virus protein

Harvard Medical School scientists reveal structure of vesicular stomatitis virus protein

Published on July 3, 2015 at 5:17 AM 

Viruses need us. In order to multiply, viruses have to invade a host cell and copy their genetic information. To do so, viruses encode their own replication machinery or components that subvert the host replication machinery to their advantage.

Ebola virus and rabies virus, two of the most lethal pathogens known to humans, belong to an order of RNA viruses that share a common strategy for copying their genomes inside their hosts. Other relatives include Marburg virus, measles, mumps, respiratory syncytial virus and vesicular stomatitis virus (VSV). Scientists study VSV, which causes acute disease in livestock but typically does not lead to illness in people, as a model for viruses that are harmful to humans.

Now a team from Harvard Medical School, using electron cryomicroscopy (imaging frozen specimens to reduce damage from electron radiation), has for the first time revealed the structure of a VSV protein at the atomic level. Called polymerase protein L, it is required for viral replication in this group of RNA viruses. The findings are published in Cell.

"We now have a better understanding of how RNA synthesis works for these viruses," said Sean Whelan, HMS professor of microbiology and immunobiology and senior author of the paper. "I think if you were trying to develop a viral-specific target to block the replication of one of these viruses, having the structure of the polymerase protein would help."

Scientists already know how these RNA viruses infect cells. They start by delivering a large protein RNA complex, which is viral RNA enclosed in a protein coat. The protein that copies viral RNA is polymerase protein L, which conducts all the enzymatic activities needed to synthesize RNA and then add a cap structure to its end to ensure it doesn't get destroyed by the cell--and to ensure that it can be translated into protein.

While researchers have known the atomic structures of the protein that coats the viral RNA, there are no data on protein L's atomic structure.

Antiviral drugs that target polymerase molecules are based in part on knowing their structure. That approach has been successful against HIV and herpes and hepatitis C viruses. But for the class of viruses known as nonsegmented negative-strand RNA viruses, finding the structure of polymerase protein L has been challenging.

The "L" stands for large. Larger proteins are often difficult to produce and to purify, Whelan said. Protein L is also flexible, with many functional fragments that are hard to isolate. The viruses evolved to make only small quantities of this protein.

Five years ago, using a lower-resolution form of electron microscopy in which the protein is visualized in the presence of negative stain, Whelan's team was able to detect at low resolution a structure that looked like a doughnut with three globular domains. Those earlier studies were informative, but the approach could not provide the atomic level of resolution the team ultimately needed.

Advances in electron cryomicroscopy encouraged them to try again. A team from Whelan's lab, working with a group led by Stephen Harrison, Giovanni Armenise - Harvard Professor of Basic Biomedical Science at HMS and a Howard Hughes Medical Institute (HHMI) investigator, was able to collect data from their viral samples that gave them much greater resolution. They also were able to align the images they collected into a three-dimensional model of polymerase protein L.

Into the density map obtained from these studies, members of the team built an atomic model of the polypeptide chain of VSV L protein. Solving this puzzle was a significant challenge and also involved the team of Nikolaus Grigorieff at HHMI's Janelia campus.

The result? An atomic level model of polymerase protein L's structure for VSV, which will form the basis for understanding the L protein of the other viruses in the order.

"The Ebola protein will look the same, the rabies protein will look the same, the other L proteins will look the same," Whelan said. "There will be some subtle differences reflecting the precise nature of amino acids, but we know that they're functionally and structurally the same."

Knowing the structure means scientists can explore how RNA synthesis is working in these viruses.

"It begins to suggest ways that we can perhaps pull apart other proteins that have not been so easy to express, such as the L protein in Ebola," Whelan said. "It doesn't mean we're going to have inhibitors immediately, but this is an important step, I think, towards that longer-term goal."

Source:

Harvard Medical School

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por cyto às 11:37

Sábado, 04.07.15

new protein that affects growth of secondary breast tumours in the brain

Scientists identify new protein that affects growth of secondary breast tumours in the brain

Published on July 1, 2015 at 7:19 AM 

Scientists from the University of Leeds and The Institute of Cancer Research, London, have discovered a new protein which triggers the growth of blood vessels in breast cancer tumours which have spread to the brain, a common location which breast cancer can spread to.

Dr Georgia Mavria's team in the School of Medicine at Leeds found that by withholding the DOCK4 protein in mouse models, a particular part of the blood vessel did not form as quickly, meaning tumours grew at a slower rate.

Dr Mavria said: "We want to understand how these tumours form and grow, but we still need to do more research to stop these tumours growing altogether.

"The finding gives an important indicator of how the protein affects the growth of secondary breast tumours in the brain. The discovery could also enable experts to predict which patients might be at risk of their breast cancer spreading, and develop drugs to prevent the growth of secondary tumours."

Working with Professor Chris Marshall, Professor of Cell Biology at The Institute of Cancer Research, London and the late Dr Tony Pawson at the Lunenfeld-Tanenbaum Research Institute in Toronto, researchers found that a complex of two related proteins, DOCK4 and DOCK9, is critical in the formation of the lumen, the interior space of a vessel through which blood flows.

By impeding the speed at which the lumen forms, tumours are not fed as effectively by blood vessels.

Normally, when breast cancer spreads to other parts of the body, it forces new blood vessels to form to supply it with nutrients and oxygen to help it to grow, resulting in tumours that are very difficult to treat.

Professor Marshall said: "Our study reveals new insights into how the complex process of forming blood vessels is controlled. This knowledge could lead to new approaches to preventing the blood supply to tumours and metastases. If we can find new ways to reduce the blood supply to tumours, we might be able to find new ways to slow cancer growth in future."

The research, which has been published in Nature Communications, was funded by Breast Cancer Now, Yorkshire Cancer Research and Cancer Research UK.

Dr Matthew Lam, Senior Research Communications Officer at Breast Cancer Now, said: "These findings could one day help us better identify and treat patients that might be at risk of their breast cancer spreading to the brain, a particularly common site for metastasis.

"12,000 women have their lives cut short by breast cancer in the UK each year. An understanding of what is happening on a molecular level - such as the role played by DOCK proteins - will be essential if we are to find ways to prevent secondary tumours and finally stop women dying from the disease."

Kathryn Scott, Head of Research and Innovation at Yorkshire Cancer Research, said: "Tumours need blood vessels to grow, but these blood vessels could be the cancer's weakest link because it is believed that they are less able to become resistant to drugs than the cancer cells themselves. Targeting drugs to the blood vessels that are serving the tumour rather than the tumour itself is an exciting new area of research and we are supporting a number of projects in Yorkshire which are investigating this approach."

Dr Aine McCarthy, Science Information Officer at Cancer Research UK, said: "This research shows for the first time that a molecule called DOCK4 is a key player in tumour blood vessel development and blocking it could slow tumour growth by starving the cancer cells. But the study was carried out in mice, so more research is needed to see if drugs can be developed that target the molecule and whether this approach would be safe and effective in people with cancer."

Source:

University of Leeds

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por cyto às 11:34

Sábado, 04.07.15

way to stop growth of cancer cells by targeting the Warburg Effect

SLU researchers find way to stop growth of cancer cells by targeting the Warburg Effect

Published on June 26, 2015 at 10:55 PM 

In research published in Cancer Cell, Thomas Burris, Ph.D., chair of pharmacology and physiology at Saint Louis University, has, for the first time, found a way to stop cancer cell growth by targeting the Warburg Effect, a trait of cancer cell metabolism that scientists have been eager to exploit.

Unlike recent advances in personalized medicine that focus on specific genetic mutations associated with different types of cancer, this research targets a broad principle that applies to almost every kind of cancer: its energy source.

The Saint Louis University study, which was conducted in animal models and in human tumor cells in the lab, showed that a drug developed by Burris and colleagues at Scripps Research Institute can stop cancer cells without causing damage to healthy cells or leading to other severe side effects.

The Warburg Effect

Metabolism -- the ability to use energy -- is a feature of all living things. Cancer cells aggressively ramp up this process, allowing mutated cells to grow unchecked at the expense of surrounding tissue.

"Targeting cancer metabolism has become a hot area over the past few years, though the idea is not new," Burris said.

Since the early 1900s, scientists have known that cancer cells prefer to use glucose as fuel even if they have plenty of other resources available. In fact, this is how doctors use PET (positron emission tomography) scan images to spot tumors. PET scans highlight the glucose that cancer cells have accumulated.

This preference for using glucose as fuel is called the Warburg effect, or glycolysis.

In his paper, Burris reports that the Warburg effect is the metabolic foundation of oncogenic (cancer gene) growth, tumor progression and metastasis as well as tumor resistance to treatment.

Cancer's goal: to grow and divide

Cancer cells have one goal: to grow and divide as quickly as possible. And, while there are a number of possible molecular pathways a cell could use to find food, cancer cells have a set of preferred pathways.

"In fact, they are addicted to certain pathways," Burris said. "They need tools to grow fast and that means they need to have all of the parts for new cells and they need new energy."

"Cancer cells look for metabolic pathways to find the parts to grow and divide. If they don't have the parts, they just die," said Burris. "The Warburg effect ramps up energy use in the form of glucose to make chemicals required for rapid growth and cancer cells also ramp up another process, lipogenesis, that lets them make their own fats that they need to rapidly grow."

If the Warburg effect and lipogenesis are key metabolic pathways that drive cancer progression, growth, survival, immune evasion, resistance to treatment and disease recurrence, then, Burris hypothesizes, targeting glycolysis and lipogenesis could offer a way to stop a broad range of cancers.

Cutting off the energy supply

Burris and his colleagues created a class of compounds that affect a receptor that regulates fat synthesis. The new compound, SR9243, which started as an anti-cholesterol drug candidate, turns down fat synthesis so that cells can't produce their own fat. This also impacts the Warburg pathway, turning cancer cells into more normal cells. SR9243 suppresses abnormal glucose consumption and cuts off cancer cells' energy supply.

When cancer cells don't get the parts they need to reproduce through glucose or fat, they simply die.

Because the Warburg effect is not a feature of normal cells and because most normal cells can acquire fat from outside, SR9243 only kills cancer cells and remains non-toxic to healthy cells.

The drug also has a good safety profile; it is effective without causing weight loss, liver toxicity, or inflammation.

Promising Results So far, SR9243 has been tested in cultured cancer cells and in human tumor cells grown in animal models. Because the Warburg pathway is a feature of almost every kind of cancer, researchers are testing it on a number of different cancer models.

"It works in a wide range of cancers both in culture and in human tumors developing in animal models," Burris said. "Some are more sensitive to it than others. In several of these pathways, cells had been reprogramed by cancer to support cancer cell growth. This returns the metabolism to that of more normal cells."

In human tumors grown in animal models, Burris said, "It worked very well on lung, prostate, and colorectal cancers, and it worked to a lesser degree in ovarian and pancreatic cancers."

It also seems to work on glioblastoma, an extremely difficult to treat form of brain cancer, though it isn't able to cross the brain/blood barrier very effectively. The challenge for researchers in this scenario will be to find a way to allow the drug to cross this barrier, the body's natural protection for the brain, which can make it difficult for drug treatments to reach their target.

And, in even more promising news, it appears that when SR9243 is used in combination with existing chemotherapy drugs, it increases their effectiveness, in a mechanism apart from SR9243's own cancer fighting ability.

Source:

Saint Louis University

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