Tag: cancer cells

Neutron reflectometry reveals how cancer cells can avoid programmed cell death

Neutron reflectometry reveals how cancer cells can avoid programmed cell death

Researchers have revealed a mechanism by which cancer cells can avoid programmed cell death. The team, from ISIS, the European Spallation Source (ESS), Lund University, the University of Umeå, the Institut Laue-Langevin (ILL) and Diamond Light Source, used an integrated combination of techniques to investigate how the Bax and Bcl-2 proteins involved in regulating programmed cell death, or apoptosis, interact at the surface of the mitochondrial outer membrane.

Apoptosis is one of the processes our body uses to control cell growth and proliferation. It plays a vital role in embryo development, in removing old or damaged cells, and in our immune systems. However, when it goes wrong, as in many cancers, those cells can escape their apoptotic removal and rapidly multiply to form tumours. Many cancer therapies, such as chemotherapy or radiotherapy, treat cancers by causing DNA damage or stressing cells, which leads to apoptosis. However, many tumours can also become treatment resistant by escaping even treatment-induced apoptotic death.

Controlling apoptosis

One of the key proteins that controls apoptosis is called Bax. Bax works by creating pores in mitochondrial membranes to start a biochemical cascade that results in cell death. Bax is usually tightly controlled by Bcl-2 proteins, which bind Bax and prevents it forming pores. The gene for Bcl-2 is involved in almost 50% of human cancers; these cancerous cells often produce more Bcl-2, leading to tumour development and protecting the cancerous cells from therapies.

To understand precisely how Bcl-2 and Bax interact, the researchers used a combination of neutron reflectometry on the Surf and Offspec instruments at ISIS and on Figaro at the Institut Laue Langevin, electron microscopy at eBIC, and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). They created a supported lipid bilayer resembling the mitochondrial outer membrane and which contained Bcl-2 proteins.

A two-step process in avoiding apoptosis

Kinetics of Bax sequestration by Bcl-2 at membrane level: from initial contact to oligomerization

The team found that, without Bcl-2, introducing Bax disrupted the membrane. When the membrane contained Bcl-2 the researchers initially saw a direct correlation between the amount of Bcl-2 in the membrane and the amount of Bax on the membrane surface, suggesting the Bcl-2 was binding directly to the Bax and preventing it from forming pores. Over time, however, they saw a second, slower process. The Bax proteins formed clusters, or oligomers, standing vertically upwards from the membrane surface, which sequestered Bax, prevented pore formation.

Read more on the Diamond website

Bringing cryo-correlative hard X-ray microscopy to life science

Bringing cryo-correlative hard X-ray microscopy to life science

Scientists led by the ESRF, UGA and INSERM have developed cryo-correlative nano-imaging, a new technique that combines lab cryo-fluorescence microscopy, cryo X-ray fluorescence nanoimaging and phase-contrast nano-tomography on ID16A. The results are published in ACS Nano.

Biologists have long wanted to answer a deceptively simple question: what are the structures we see inside cells actually made of? Visible light fluorescence microscopy shows where organelles are, but not their chemical composition. Hard X-rays can map the chemistry but do not necessarily see the organelles. Cryo-correlative nanoprobe work remains rare, particularly for 3D elemental imaging of whole frozen cells.

A new study at ID16A beamline of the ESRF offers a practical solution. An international team has developed an integrated cryogenic workflow that links laboratory cryo-fluorescence microscopy to targeted cryo X-ray fluorescence (XRF) nano-imaging and phase-contrast nano-tomography.

With this new method, they have tracked therapeutic nanoparticles from the European ScanNtreat project as they moved through cancer cells, showing both where the particles went and what happened to them.

The first author of the publication, Dmitry Karpov, former ESRF scientist and now researcher at the Université Grenoble Alpes, explains how this new development can lead to applications: “This is an example of what the ESRF aims to do: to turn cutting-edge instrumentation into discoveries with direct impact on people’s lives, in this case for medicine and life sciences”.

Read more on the ESRF website

Attacking cancer cells from the inside out

Attacking cancer cells from the inside out

Researchers from the University of Toronto (U of T) are harnessing the power of proteins to stop cancer cells in their tracks.

“Proteins are the workhorses of the cell,” said Walid A. Houry, professor of biochemistry at U of T. “They define the cell and allow it to divide or migrate if needed.”

The team is especially interested in proteases, enzymes that chew up old or misfolded proteins and act as cellular quality control. Houry and his colleagues used the CMCF beamline at the Canadian Light Source (CLS) at the University of Saskatchewan to identify key compounds affecting these quality control mechanisms that cause cell dysfunction and, ultimately, cell death. Their research paper was recently published in Structure.

“Let’s say you have a small puppy and when you leave it in the room, it starts chewing your sofa, your carpet; it’s just hyper and eating everything up,” Houry said. The compounds cause the proteases to act like the puppy, “and the cell cannot handle this type of disruption to its machinery.”

By targeting the cell’s self-destruct button, Houry’s team, including collaborators at Madera Therapeutics, is designing a new approach to cancer therapy. Synchrotron techniques allowed the researchers to visualize the interaction between their compounds and the proteases.

Houry said hard-to-treat cancers like glioblastomas and certain types of breast cancers are good candidates for this new approach.

“Instead of inhibiting a protease, we are hyperactivating the protease, and that is unique.”

The CLS is crucial to the team’s work.

“Synchrotron technology is extremely important for us and our structure-based drug design,” he said. “We want to know why the protein is going wild when we add our compound.”

Read more on the CLS website

Image: Houry research team

Understanding how a key antibody targets cancer cells

Understanding how a key antibody targets cancer cells

Immunotherapy can be used as a precise intervention in cancer treatments. Jean-Philippe Julien is a Canada Research Chair in Structural Immunology, a Senior Scientist in the Molecular Medicine Program at The Hospital for Sick Children (SickKids), and an Associate Professor in the Departments of Biochemistry and Immunology at the University of Toronto. Along with colleagues from the U.S., Spain and Canada, he used the Canadian Light Source at the University of Saskatchewan to study how a candidate antibody therapeutic interacts with a surface receptor on cancer cells, which provides important molecular insights for designing improved cancer therapies. He mentioned how the synchrotron is “incredibly important for researchers like myself” and how “we cannot do the research that we do without it.” The team used the CMCF beamline at the CLS and their findings were published in the Journal of Biological Chemistry.Immunotherapy can be used as a precise intervention in cancer treatments. Jean-Philippe Julien is a Canada Research Chair in Structural Immunology, a Senior Scientist in the Molecular Medicine Program at The Hospital for Sick Children (SickKids), and an Associate Professor in the Departments of Biochemistry and Immunology at the University of Toronto. Along with colleagues from the U.S., Spain and Canada, he used the Canadian Light Source at the University of Saskatchewan to study how a candidate antibody therapeutic interacts with a surface receptor on cancer cells, which provides important molecular insights for designing improved cancer therapies. He mentioned how the synchrotron is “incredibly important for researchers like myself” and how “we cannot do the research that we do without it.” The team used the CMCF beamline at the CLS and their findings were published in the Journal of Biological Chemistry.

Learn more on the CLS website

Image: Jean-Philippe Julien

Credit: Canadian Light Source