cancer – Page 2 – Lightsources.org

2019/10/032019/11/08

A research, led by the ALBA Synchrotron and funded by the European project NANOCANCER, has analysed the impact of nanoparticles in radiotherapy of glioma tumour cells.

Combining radiotherapy with nanoparticles can increase the efficacy of cancer treatments. The experiment has been carried out at the MIRAS beamline of ALBA, devoted to infrared microspectroscopy.

The use of nanotechnology in medicine is nothing short of revolutionary. Nanosensors for diagnosis, nanoparticles for drug delivery or nanodevices that can regenerate damaged tissue are changing the way we face and treat several diseases.

Combining radiotherapy with nanoparticles is a promising strategy to increase the efficacy of cancer treatments. High-atomic number nanoparticles are used as tumour radiosensitizers: tumour cells previously loaded with nanoparticles enhance the radiation effects when exposed to radiotherapy. “It’s a kind of knock-on effect; the interaction of the radiation with the nanoparticles generates short-range secondary radiation that induces a local dose enhancement in the tumour cells. However, the mechanisms underlying the synergistic effects involved in these techniques are not clearly understood’, says Immaculada Martínez-Rovira, Marie Curie scientist of ALBA and expert in the development of innovative radiotherapy approaches.

>Read more on the ALBA website

Image: Researcher Imma Martínez-Rovira, Marie Curie scientist of ALBA and expert in the development of innovative radiotherapy approaches.

Structure and functional binding epitopes of VISTA

2019/09/302019/10/10

V-domain Ig Suppressor of T-cell Activation (VISTA) is an immune checkpoint protein involved in the regulation of T cell activity. Checkpoint proteins are overexpressed by cancer cells or surrounding immune cells and prevent anti-tumor activity by co-opting natural regulation mechanisms to escape immune clearance. Compared to healthy tissues, VISTA is upregulated on tumor infiltrating leukocytes, including high expression on myeloid-derived suppressor cells (MDSCs). Through VISTA signaling, these inhibitory immune cells prevent effective antigen presentation and indirectly promote tumor growth. VISTA is implicated in a number of human cancers including skin (melanoma), prostate, colon, pancreatic, ovarian, endometrial, and non-small cell lung. VISTA is a known member of the B7 protein family but the mechanism of action is still unclear as VISTA has been shown to function as both a ligand^1,2 and a receptor³. In the model of VISTA as a receptor, the proposed ligand of interaction is V-set and immunoglobulin domain containing 3 (VSIG3)^4,5.

>Read more on the SSRL website

Image: Structure of human VISTA with extended C-C’ loop (blue), mapped VSTB/VSIG3 binding epitope (red), and disulfide bonds (yellow).

Preventing tumour metastasis

2019/08/222019/08/27

Researchers at the Paul Scherrer Institute, together with colleagues from the pharmaceutical company F. Hoffmann-La Roche AG, have taken an important step towards the development of an agent against the metastasis of certain cancers.

Using the Swiss Light Source, they deciphered the structure of a receptor that plays a crucial role in the migration of cancer cells. This makes it possible to identify agents that could prevent the spread of certain cancer cells via the body’s lymphatic system. The researchers have now published their results in the journal Cell.
When cancer cells spread in the body, secondary tumours, called metastases, can develop. These are responsible for around 90 percent of deaths in cancer patients. An important pathway for spreading the cancer cells is through the lymphatic system, which, like the system of blood vessels, runs through the entire body and connects lymph nodes to each other. In the migration of white blood cells through this system, for example to coordinate the defense against pathogens, one special membrane protein, the chemokine receptor 7 (CCR7) plays an important role. It sits in the shell of the cells, the cell membrane, in such a way that it can receive external signals and relay them to the interior. Within the framework of a joint project with the pharmaceutical company F. Hoffmann-La Roche AG (Roche), researchers at the Paul Scherrer Institute (PSI) have for the first time been able to decipher the structure of CCR7 and lay the foundation for the development of a drug that could prevent metastasis in certain prevalent cancer types, such as colorectal cancer.

Revolutionary discovery in leukemia research

2019/07/022019/07/16

Leukemia affects over 6,000 Canadians per year. A team of researchers used the Canadian Light Source (CLS) at the University of Saskatchewan to discover a new way to kill leukemia cancer cells. When the scientists hyperactivated the “garbage disposal systems” of leukemia cells, it caused the cancer to die.
The researchers believe this finding will transform the direction of cancer therapy by focusing on a protein that was previously believed to be impossible to target. Their study was featured on the cover of the journal Cancer Cell.
“It was a major advancement to visualize the structural biology through crystallography facilities at CLS and to prove conclusively that ONC201 binds and hyperactivates ClipP proteases to induce cell death,” said co-author Dr. Aaron Schimmer from the Princess Margaret Cancer Centre and the University of Toronto.

Image: Interface of two heptamer rings in an apparently closed conformation of human mitochondrial ClpP.

The interaction between two proteins involved in skin mechanical strength

2019/05/172019/05/28

A research team from the Centro de Investigación del Cáncer of the Universidad de Salamanca has obtained a detailed 3D image of the union between two hemidesmosomal proteins.

The structure of this complex has been unveiled using XALOC beamline techniques, at the ALBA Synchrotron. The results, published in “Structure”, provide insights to understand how these epithelial adhesion structures are formed. Researchers from Centro de Investigación del Cáncer – Instituto de Biología Molecular y Celular del Cáncer of Salamanca, from Centro Universitario de la Defensa in Zaragoza, and from the Netherlands Cancer Institute in Amsterdam have described how two essential proteins interact to each other in order to join epidermis and dermis together. This study reveals at atomic scale how the binding between two hemidesmosomal proteins called integrin α6β4 and BP230 takes place.
Epithelial tissues, such as epidermis, settle on fibrous sheets called basement membrane, formed by extracellular matrix proteins. The junction between epithelia and basement membrane happens through hemidesmosomes, multi-protein complexes located at the membrane of epithelial cells. Integrin α6β4 is an essential protein of the hemidesmosomes, which adheres to proteins of the basement membrane. Inside the cell cytoplasm, plectin and BP230 proteins bind to α6β4 and connect it to the intermediate filaments of the cytoskeleton. Genetic or autoimmune alterations that affect the hemidesmosomal proteins reduce skin resistance and cause diseases such as bullous pemphigoid and various types of epidermolysis bullosa.

>Read more on the ALBA website

Image: Structure of β4(WT)-BP230 complex.

Researchers create the first maps of two melatonin receptors essential for sleep

2019/04/242019/05/03

A better understanding of how these receptors work could enable scientists to design better therapeutics for sleep disorders, cancer and Type 2 diabetes.

An international team of researchers used an X-ray laser at the Department of Energy’s SLAC National Accelerator Laboratory to create the first detailed maps of two melatonin receptors that tell our bodies when to go to sleep or wake up, and guide other biological processes. A better understanding of how they work could enable researchers to design better drugs to combat sleep disorders, cancer and Type 2 diabetes. Their findings were published in two papers today in Nature.

The team, led by the University of Southern California, used X-rays from SLAC’s Linac Coherent Light Source (LCLS) to map the receptors, MT1 and MT2, bound to four different compounds that activate them: an insomnia drug, a drug that mixes melatonin with the antidepressant serotonin, and two melatonin analogs.

>Read more on the LCLS at SLAC website

Image: The researchers showed that both melatonin receptors contain narrow channels embedded in the cell’s fatty membranes. These channels only allow melatonin, which can exist happily in both water and fat, to pass through, preventing serotonin, which has a similar structure but is only happy in watery environments, from binding to the receptor. They also uncovered how some much larger compounds only target MT1 despite the structural similarities between the two receptors.
Credit: Greg Stewart/SLAC National Accelerator Laboratory

Understanding the viruses that kill cancer cells

2019/04/122019/04/16

Taking inspiration from virology to find better treatments for cancer

There are some viruses, called oncolytic viruses, that can be trained to target and kill cancer cells. Scientists in the field of oncolytics want to engineer these viruses to make them safer and more effective so they can be used to treat more people and different types of cancers. To achieve this, they first have to fully understand at the molecular level all the different ways that the virus has evolved to infect healthy cells and cause disease. A research team from Cardiff University set out to better understand how a protein on the surface of a virus often used to kill cancer, called an adenovirus, binds to human cells to cause an infection. Using X-ray crystallography, the team was able to determine the structure of one the key adenovirus proteins. Using this information and after extensive computational analysis, the research team realised the virus was not binding the receptor on the cells that was originally thought. This has important implications for the development of new virotherapies and engineering of viruses to treat cancer. The more thoroughly the researchers can understand how the adenoviruses interact with cancer cells at the molecular level, the more safe and effective treatments can be brought to clinical trial in the future.

Absorber captures excess chemotherapy drugs

2019/03/222019/04/10

The work opens up a new route to fighting cancer that minimizes drug toxicity and enables personalized, targeted, high-dose chemotherapy.

Most anticancer drugs are poisonous, so doctors walk a delicate line when administering chemotherapy. A dose must be sufficient to kill or stop the growth of cancer cells in the target organ, but not high enough to irreparably damage a patient’s other organs. To avoid this, doctors can thread catheters through the bloodstream to deliver chemotherapy drugs directly to the site of the tumor—a method known as intra-arterial chemotherapy. Still, typically more than half of the dose injected into the body escapes the target organ. Several years ago, researchers began working on a major improvement: placing a device “downstream” of the targeted organ to filter out excess chemo so that much less of the drug reaches the body as a whole.

>Read more on the Advanced Light Source

Image: (extract, see here the full image)
(a) Diagram of the proposed approach for drug capture using a 3D-printed cylindrical absorber. (b) Chemical structure of doxorubicin, the chemotherapy drug used in this study. (c) Schematic of the endovascular treatment of liver cancer. Excess drug molecules are captured by the absorber in the vein draining the organ. An introducer sheath guides the absorber to the desired location via a guide wire.

A new molecule could help put the STING on cancer

2019/03/132019/03/18

The protein STING (stimulator of interferon genes) is a component of the innate immune system. It plays a major role in the immune response to cancer, and abnormal STING signaling has been shown to be associated with certain cancers. Immunomodulatory approaches using agonists to target STING signaling are therefore being investigated as anticancer treatments. However, the compounds in clinical trials typically are injected intratumorally in patients with solid cancers. In this study, researchers discovered a novel STING agonist, known as an amidobenzimidazole (ABZI), which can be given by intravenous injection and could therefore potentially open up its evaluation as a treatment for hard-to-reach cancers. Using x-ray diffraction data collected at the U.S. Department of Energy’s Advanced Photon Source (APS), researchers from GlaxoSmithKline (GSK) investigated ABZI compounds and STING. Their results, published in the journal Nature, may have important implications for anticancer immunotherapy.

STING is a protein that mediates innate immunity, and one function of the STING signaling pathway is in mobilizing an immune response against tumors. STING proteins can be activated by cyclic dinucleotides, small molecules that are made by the cytosolic DNA sensor, cGAS, upon sensing of DNA leaking out of the nucleus as a result of DNA damage, including that which might be associated with cancer development.

Figure: X-ray crystal structure of the STING protein bound to one of the new molecules.

Clear view of “Robo” neuronal receptor opens door for new cancer drugs

2019/03/072019/03/12

During brain development, billions of neuron nerve cells must find accurate pathways in the brain in order to form trillions of neuronal circuits enabling us to enjoy cognitive, sensory and emotional wellbeing.

To achieve this remarkable precision, migrating neurons use special protein receptors that sense the environment around them and guide the way so these neurons stay on the right path. In a new study published in Cell, researchers from Bar-Ilan University and Tel Aviv University in Israel, EMBL Grenoble in France and University of Exeter in the UK report on their discovery of the intricate molecular mechanism that allows a key guidance receptor, “Robo”, to react to signals in its environment.

One of the most important protein signaling systems that guide neurons consists of the cell surface receptor “Robo” and its external guidance cue, “Slit”. “Slit and Robo can be identified in virtually all animals with a nervous system, from a 1 mm-long nematode all the way to humans,” explains researcher Yarden Opatowsky, associate professor and head of the Laboratory of Structural Biology at Bar-Ilan University and who led the research.

Image: A surface representation of the crystal structure of the extracellular portion of human Robo2. The yellow region represents the domain where dimerisation takes place. Here, we see it blocked by the other domains, meaning dimerisation cannot take place and that Robo2 is inactivated.
Credit: Y. Opatowsky.

Mechanism of thiopurine resistance in acute lymphoblastic leukemia

2019/02/282019/03/13

Acute lymphoblastic leukemia (ALL) is an aggressive lymphoid malignancy that is currently the leading cause of cancer in pediatric patients¹. Despite intensified chemotherapy regimens, the cure rates of ALL only approaches 40%². Specific mutations in the cytosolic 5’-nucleotidase II (NT5C2) gene are present in about 20% of relapsed pediatric T-ALL and 3-10% of relapsed B-precursor ALL cases^3,4.

NT5C2 is a cytosolic nucleotidase that maintains intracellular nucleotide pool levels by exporting excess purine nucleotides out of the cell⁵. NT5C2 can also dephosphorylate and inactivate the metabolites of the 6-thioguanine (6-TG) and 6-mercaptopurine (6-MP) commonly used to treat ALL⁶. Thus, relapse associated activating mutations in NT5C2 confer resistance to 6-MP and 6-TG chemotherapy. Upon allosteric activation, a disordered region of NT5C2 adopts a helical configuration (helix A) and facilitates substrate binding and catalysis (Fig. 1a)⁷. Mutations in this regulatory region of NT5C2 have been modeled to strongly activate NT5C2. However, the majority of NT5C2 mutations associated with relapsed ALL do not occur in this region.
To better understand the mechanisms by which these gain-of function NT5C2 mutations lead to increased nucleotidase activity, Dieck, Tzoneva, Forouhar and colleagues investigated additional regulatory elements that may control NT5C2 activation. They collected crystallographic data for several mutant NT5C2 homotetramers at SSRL (NT5C2-537X D52N/D407A in active state (BL9-2), NT5C2-Q523X D52N in basal state and in active state (BL14-1) and full-length NT5C2 R39Q/D52N in basal state (BL12-2)) and used the structural information as a guide in the understanding of the mechanistic details.

Figure (a) A ribbon diagram of the active structure of NT5C2 WT, in which the allosteric helix A (αA) is shown in dark purple. The N and C termini amino acids (S4 and S488), and the termini amino acids (L402 and R421) of the disordered region in the arm segment are also labeled. Panels b and c shows ribbon and surface (for subunit B) depictions of basal (b) and active dimers (c) of WT.

Encapsulation of drugs for new cancer treatments

2019/02/192019/02/27

Research develops hydrogel from silk protein with potential application in photodynamic therapy

Cancer is a set of diseases characterized by uncontrolled multiplication of cells. One of the main methods for treating this disease is chemotherapy, which uses drugs to block the growth of those cells or to destroy them. In this way, most drugs used interfere with mitosis, the cellular mechanism by which new cells are produced. Therefore, both cancerous and healthy cells are affected, leading to several side effects.
Worldwide, considerable effort has been directed at developing new methods that act directly on the target of treatment. This is the case of so-called photodynamic therapy (PDT), a minimally invasive therapeutic procedure that selectively acts on malignant cells.
The procedure involves the administration of a light-sensitive substance, called a photosensitizing agent. When irradiated at specific wavelengths, the photosensitizer releases oxygen in reactive chemical forms that promote the death of malignant cells, infectious agents and the removal of burns.

Revealing the path of a metallodrug in a breast cancer cell

2019/02/042019/02/15

Some types of cancer cannot be treated with classical chemotherapy. Scientists from Inserm, CNRS, Sorbonne University, PSL university, University Grenoble Alpes and ESRF, the European Synchrotron, are working on a metallorganic molecule as an antitumor drug. Their research has given thorough insights into its mechanism in attacking cancer cells. This study is published in Angewandte Chemie.

Triple-negative breast cancer, which represents 10-20% of breast cancers, is not fuelled by hormones. In fact, it tests negative for estrogen and progesterone receptors and excess HER2 protein. This means that it does not respond to hormonal therapy and antibody medicines. Given that it is more aggressive and often has a higher grade than other types of breast cancer, the scientific community is relentlessly trying to find a treatment.

>Read more on the ESRF website

Image: X-ray fluorescence maps of potassium, an essential physiological element of the cell (K, in pink), and, osmium a constitutive element of the metallocifen (Os, in green), in hormone-independent breast cancer cells exposed to the osmocenyl-tamoxifen derivatives.
Credit: Sylvain Bohic.

X-ray fluorescence imaging could open up new diagnostic possibilities in medicine

2018/11/162018/11/29

Using gold to track down diseases

A high-precision X-ray technique, tested at PETRA III, could catch cancer at an earlier stage and facilitate the development and control of pharmaceutical drugs. The test at DESY’s synchrotron radiation source, which used so-called X-ray fluorescence for that purpose, has proved very promising, as is now being reported in the journal Scientific Reports by a research team headed by Florian Grüner from the University of Hamburg. The technique is said to offer the prospect of carrying out such X-ray studies not only with higher precision than existing methods but also with less of a dose impact. However, before the method can be used in a clinical setting, it still has to undergo numerous stages of development.

The idea behind the procedure is simple: tiny nanoparticles of gold having a diameter of twelve nanometres (millionths of a millimetre) are functionalised with antibodies using biochemical methods. “A solution containing such nanoparticles is injected into the patient,” explains Grüner, a professor of physics at the Centre for Free-Electron Laser Science (CFEL), a cooperative venture between DESY, the University of Hamburg and the Max Planck Society. “The particles migrate through the body, where the antibodies can latch onto a tumour that may be present.” When the corresponding parts of the patient’s body are scanned using a pencil X-ray beam, the gold particles emit characteristic X-ray fluorescence signals, which are recorded by a special detector. The hope is that this will permit the detection of tiny tumours that cannot be found using current methods.

Image: Gold nanoparticles spiked with antibodies can specifically attach to tumors or other targets in the organism and can be detected there by X-ray fluorescence.
Credit: Meletios Verras [Source]

New approach to breast cancer detection

2018/10/032018/10/04

Phase contrast tomography shows great promise in early stages of study and is expected to be tested on first patients by 2020.

An expert group of imaging scientists in Sydney and Melbourne are using the Imaging and Medical Beamline (IMBL) at the Australian Synchrotron as part of ongoing research on an innovative 3D imaging technique to improve the detection and diagnosis of breast cancer.

The technique, known as in-line phase-contrast computed tomography (PCT), has shown advantages over 2D mammography with conventional X-rays by producing superior quality images of dense breast tissue with similar or below radiation dose.
Research led by Prof Patrick Brennan of the University of Sydney and Dr Tim Gureyev at the University of Melbourne with funding from the NHMRC and the support of clinicians in Melbourne including breast surgeon Dr Jane Fox, is now focused on demonstrating the clinical usefulness of the technique.
Together with Associate Professor Sarah Lewis and Dr SeyedamirTavakoli Taba from the University of Sydney heading clinical implementation, the technique is expected to be tested on the first patients at the Australian Synchrotron by 2020.

Image: CT reconstruction of 3D image of mastectomy sample revealing invasive carcinoma

Just like lego – studying flexible protein for drug delivery

2018/08/302018/09/06

Researchers from the Sapienza University of Rome and its spin-off company MoLiRom (Italy) are spending the weekend at the ESRF to study a protein that could potentially transport anticancer drugs.

Ferritin is a large spherical protein (20 times bigger than haemoglobin) that stores iron within its cavity in every organism. Just like a lego playset, Ferritin assembles and disassembles. It is also naturally targeted to cancer cells. These are the reasons why Ferritin is a great candidate as a drug-transport protein to fight cancer. An international team of scientists from “Sapienza” University of Rome and the SME MoLiRom (Italy) came to the ESRF to explore a special kind of ferritin that shows promising properties. “This is an archaebacterial ferritin that have transformed into a humanised ferritin to try to tackle cancer cells”, explains Matilde Trabuco, a scientist at the Italian SME MoLiRom.

The mechanism looks simple enough: “Ferritin has a natural attraction to cancer cells. If we encapsulate anti-cancer drugs inside it, it will act as a Trojan horse to go inside cells, then it will open up and deliver the drug”.

Ferritins have been widely used as scaffolds for drug-delivery and diagnostics due to their characteristic cage-like structure. Most ferritins are stable and disassemble only by a harsh pH jump that greatly limits the type of possible cargo. The humanised ferritin was engineered to combine assembly at milder conditions with specific targeting of human cancer cells.