Fusion proteins are created by two genes -- originally coding for separate proteins -- joining together. Translation of the fusion gene into an active protein results in a molecule with properties derived from each of the originals. Fusion proteins are relatively commonly found in cancer cells.
The team looked at a fusion protein called NPM-ALK. Anaplastic lymphoma kinase (ALK), which physiologically is expressed only by neurons in fetal life, causes cancer when it is mistakenly expressed in non-neural tissues as a fusion protein with nucleophosphin (NPM) and other partners. NPM-ALK works by silencing the tumor suppressor gene IL-2Rã. The ALK fusion genes are active in several cancer types including some carcinomas of the lung, thyroid, and kidney.
The protein IL-2Rã is shared by receptors for several proteins called cytokines that play key roles in the maturation and growth of normal immune cells called CD4+ T cells. The Penn team found that IL-2Rã expression is inhibited in T-cell lymphoma cells expressing NPM-ALK as a result of epigenetic silencing. The IL-2Rã gene promoter is silenced by a chemical change to the DNA itself, in this case, the adding of a methyl group to DNA's molecular backbone.
Silencing of the IL-2Rã promoter via methylation is induced in malignant T cells by NPM-ALK by activating another protein called STAT3. STAT3 increases expression of one of the DNMTs and facilitates attachment of this and other DNMTs to the IL-2Rã gene promoter. Strikingly, when IL-2Rã is expressed, NPM-ALK disappears from the cancerous T cells, and they eventually die. These results demonstrate that NPM-ALK induces epigenetic silencing of the IL-2Rã gene and that IL-2Rã acts as a tumor suppressor by reciprocally inhibiting expression of NPM-ALK.
"Epigenetic silencing is not an independent event, and genetics — in the form of the aberrant fusion protein — drives an epigenetic change," says Wasik. "Is this phenomenon generalizable? Can we overcome the tumor suppressor gene silencing using inhibitors of DNA methylation, which are already approved to treat some forms of blood cancer, to inhibit the expression of NPM-ALK and possibly other cancer-causing proteins in patients?"
This approach could potentially complement inhibition of fusion protein activity as is routinely done for BCR-ABL in chronic myelogeneous leukemia and experimentally for ALK in lung carcinoma, lymphoma and other malignancies expressing ALK.
The research was funded by the grants from the National Cancer Institute and the Leukemia and Lymphoma Society.
Penn Medicine is one of the world's leading academic medical centers, dedicated to the related missions of medical education, biomedical research, and excellence in patient care. Penn Medicine consists of the Raymond and Ruth Perelman School of Medicine at the University of Pennsylvania (founded in 1765 as the nation's first medical school) and the University of Pennsylvania Health System, which together form a $4 billion enterprise.
Penn's Perelman School of Medicine is currently ranked #2 in U.S. News & World Report's survey of research-oriented medical schools and among the top 10 schools for primary care. The School is consistently among the nation's top recipients of funding from the National Institutes of Health, with $507.6 million awarded in the 2010 fiscal year.
The University of Pennsylvania Health System's patient care facilities include: The Hospital of the University of Pennsylvania -- recognized as one of the nation's top 10 hospitals by U.S. News & World Report; Penn Presbyterian Medical Center; and Pennsylvania Hospital – the nation's first hospital, founded in 1751. Penn Medicine also includes additional patient care facilities and services throughout the Philadelphia region.
Penn Medicine is committed to improving lives and health through a variety of community-based programs and activities. In fiscal year 2010, Penn Medicine provided $788 million to benefit our community.
Karen Kreeger | EurekAlert!
ADP-ribosylation on the right track
26.04.2018 | Max-Planck-Institut für Biologie des Alterns
Flavins keep a handy helper in their pocket
25.04.2018 | University of Freiburg
Magnetic resonance imaging, or MRI, is a widely used medical tool for taking pictures of the insides of our body. One way to make MRI scans easier to read is...
At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.
Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...
Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.
Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
26.04.2018 | Medical Engineering
26.04.2018 | Power and Electrical Engineering
26.04.2018 | Information Technology