Author: braniecs

Silver and Gold ‘nanocages’ might buy early detection

By Sara Braniecki

Researchers from Washington University and Purdue University collaborated to experiment with a new medical imaging technique that they hope will lead to early detection and treatment for cancer patients.  The procedure uses a pulsed laser and tiny metallic “nanocages, as the researchers call them, to create images much clearer than those created using previous techniques.

This composite image shows luminous nanocages, which appear like stars against a black background, and a living cell, at upper left. The gold-silver nanocages exhibit a bright "three-photon luminescence" when excited by the ultrafast pulsed laser, with 10-times greater intensity than pure gold or silver nanoparticles. The signal allows live cell imaging with negligible damage from heating.

The nanocages are injected into the bloodstream, and then laser pulses are shone through the patient’s skin to detect them. The nanocages are small, hollow spheres made of a combination of gold and silver. Both the nanocages are only 40 nanometers wide.  To put that into perspective, this is 100 times smaller than a red blood cell.  The laser shines light that is almost infrared and pulses 80 million times per second.

The procedure illuminates tissues and organs, allowing live cell imaging.  The precision of these images is important for accurate detection and thorough treatment of cancer.

The images produced using this technique provide a much better image than older techniques that used nanospheres made solely of gold.  The new images have greater contrast since there is less background glow of surrounding tissues.  One of the researchers from Purdue University, Ji-Xen Cheng, explains, “This lack of background fluorescence makes the images much more clear and is very important for disease detection.  It allows us to clearly identify the nanocages and the tissues.”

Another advantage of using the nanocages made of both silver and gold is that there is no resulting heat damage in the tissue.  Previously, the image needed to be enhanced to get a clear enough image that was usable.  To enhance the image, clouds of electrons moving in unison had to be induced in the tissue- this resulted in the heat damage.  Since this enhancement is no longer vital, the heat damage does not occur.

The researchers hope that the creation of the nanocages will lead to better detection and treatment.  Washington University researcher Younan Xia, whose team engineered the nanocages, explains that the productions of the nanocages will likely allow researchers “to combine imaging and therapy for better diagnosis and monitoring.”  He also foresees that the nanocages might be used to deliver time-released anticancer drugs to diseased tissue.

Further information.

Tricky tumors grow and spread

The tumor has transformed its outer layer to mimic lymph node tissue to avoid detection by the immune system.

By Sara Braniecki

Researchers from Switzerland’s Ecole Polytechnique Fédérale de Lausanne (EPFL) published a study in the March 2010 issue of Science explaining how tumor cells avoid being destroyed by the immune system.  The researchers believe that knowing how cancerous cells avoid the body’s immune system could lead to a future understanding of how to use the body’s natural defense mechanism to destroy cancerous cells.

Tumors make themselves and the surrounding area seem perfectly normal by disguising themselves as lymph nodes, which are a key part of the immune system that filters the blood and traps foreign particles.  Due to the disguise, the immune system is not phased and has no reason to take any destructive action on the cancer cells.

The researchers focused on a protein in genuine lymph nodes that attracts cells and instructs them to carry out defensive functions for the body.  Some tumors make their outer layer, with which the immune system would come into contact, appear as lymph node tissue by secreting this protein that the researchers were studying.  Since the tumors secrete the protein, they attract immune cells.   The immune cells are tricked into thinking the tumor is healthy rather than foreign.  Thus the tumor is not destroyed by the immune system, allowing it to grow and spread.

According to one of the researchers, Jacqui Shields, the concept that tumors mimic lymphoid tissue to alter the host’s immune response represents a new understanding of tumors’ interactions with the lymphatic system.  This will possibly open up a new area of study, and hopefully open up new understanding for cancer therapy.

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Hope for mixed-lineage leukemia’s hopeless prognosis

By Sara Braniecki

A team of researchers at University of Pennsylvania School of Medicine led by Xianxin Hua, MD, PhD, have gained detailed understanding of how mixed-lineage leukemia (MLL) fuels itself to continually cause blood cells to grow out of control.  The information, which the researchers published in he current (Feb 2010) issue of Cancer Cell, is imperative in the researchers pursuit to find an effective treatment for MLL patients in the near future.

“This research not only uncovers the crucial role of a normal protein key to the development of MLL, but also how the cancer cells stay alive in the first place,” says Hua.

MLL is an aggressive childhood cancer that occurs when a piece of chromosome 11 breaks off and attaches to a different chromosome, resulting in uncontrollable blood cell growth.  Children diagnosed with MLL poorly respond to common leukemia treatments, leaving little hope for these children.

When the piece from chromosome 11 attaches to a different chromosome, a protein is produced that leads to the uncontrollable blood cell growth that makes the children so ill.  The researchers call this protein the “fusion protein.”  The researchers deleted the gene for the normal protein from leukemia cells and the uncontrollable growth of cells did not occur, which led them to their conclusion that this normal protein was necessary for MLL to thrive.

Knockdown of normal MLL gene in human leukemia cells reduces leukemic infiltration in mouse bone marrow (left), compared with heavy leukemic infiltration in marrow from leukemia cells with normal MLL gene (right). Arrows denote leukemic cells.

Another crucial conclusion for their research is that the normal MLL protein and the “fusion proteins” interact due to chemical modifications on chromosomes.  These modifications allow a change to occur that increases the number of leukemia cells that survive over time and keeps a sufficient amount of leukemia stem cells present.

As Hua’s team of researchers continues to gain understanding of MLL they will hopefully find a better treatment for the patients afflicted with the disease.  Being diagnosed with a disease with such little hope for treatment and control is perhaps one of the most disheartening things that can happen to a child.  Hua’s team is on the right track to finding the treatment needed to give hope to children with MLL.

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The key to locking up cancer

Sara Braniecki

Structure of TGF-B

In the current issue of Nature Cell Biology, a team of researchers led by Philip Howe from the Department of Cancer Biology at the Lerner Research Institute explain how they worked backwards to discover the protein that triggers cancer cells to be released from the original tumor, thus giving rise to new tumors.  Knowing this can lead to the development of drugs that contain cancer to one location, making it more efficiently treatable.

The researchers already knew that a process called epithelial-mesenchymal transdifferentiation (EMT) was important for cells on the surface of a tumor to transform into cells that are able to grow a new tumor elsewhere in the body.  The researchers worked backwards through the EMT process to find out what initiates it.  The researchers discovered that a protein called disabled-2 (Dab2) activated the EMT process and Dab2’s formation was triggered by transforming growth factor-b (TGF-b).

The EMT process is often what leads to death in patients with breast, ovarian, pancreatic, and colon-rectal cancers.  With the information these researchers have discovered about cancer cells, researchers can now begin to create drugs to stop EMT and stop cancer from spreadings.  This information could also lead to understanding how other diseases progress and can be contained.

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Old Chinese Medicine, New Cancer Treatment

Sara Braniecki

    Dr. Ahmed Chadli and fellow researchers at the Medical College of Georgia believe that they are on the right track to finding a new cancer treatment using celastrol, a plant derivative derived from trees and shrubs called celastracaea that the Chinese have used to treat symptoms such as fever, chills, and inflammation for centuries.

    Dr. Chadli and his colleagues think that they can devise a way for celastrol to be used for cancer treatment by using it to inactivate P23, a protein required for cancer growth.  Normally, P23 is a chaperone protein aiding the heat shock protein 90 (Hsp90).  Hsp90 has many chaperone proteins for its many different functions, and it is challenging for researchers to find a chaperone protein that will selectively target the Hsp90 implicated in a specific tumor.  The MCG researchers believe that celastrol has the specificity to control cancer cell growth by forcing the Hsp90 to cluster together, inactivating it.

    “Cancer cells need Hsp90 more than normal cells because cancer cells have thousands of mutations.  They need chaperones all the time to keep their mutated proteins active.  By taking heat shock proteins away from cells, the stabilization occurs and cell death occurs,” explains Dr. Chadli.

Dr. Chadli in the laboratory
Dr. Chadli researching in the laboratory.

 

Dr. Chadli is a researcher and professor at the Medical College of Georgia and an alumnus of the Mayo Clinic.  He has been researching Hsp90 for over 10 years and has several works published in The Journal of Biological Chemistry and other journals.  He conducts thorough research to understand the intricacies of all the molecules and pathways associated with Hsp90.  Cancer therapy can be greatly refined with ambitious research like his.  Dr. Chadli looks forward to future studies on cancer patients with greater dosage of celastrol, hopefully leading to greater results in the therapy.

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