Now research from Rockefeller University shows that having too many stem cells, or stem cells that live for too long, can increase the odds of developing cancer.
By identifying a mechanism that regulates programmed cell death in precursor cells for blood, or hematopoietic stem cells, the work is the first to connect the death of such cells to a later susceptibility to tumors in mice. It also provides evidence of the potentially carcinogenic downside to stem cell treatments, and suggests that nature has sought to balance stem cells' regenerative power against their potentially lethal potency.
Research associate Maria Garcia-Fernandez, Hermann Steller, head of the Strang Laboratory of Apoptosis and Cancer Biology, and their colleagues explored the activity of a gene called Sept4, which encodes a protein, ARTS, that increases programmed cell death, or apoptosis, by antagonizing other proteins that prevent cell death. ARTS was originally discovered by Sarit Larisch, a visiting professor at Rockefeller, and is found to be lacking in human leukemia and other cancers, suggesting it suppresses tumors. To study the role of ARTS, the experimenters bred a line of mice genetically engineered to lack the Sept4 gene.
For several years, Garcia-Fernandez studied cells that lacked ARTS, looking for signs of trouble relating to cell death. In mature B and T cells, she could not find any, however, so she began to look at cells earlier and earlier in development, until finally she was comparing hematopoietic progenitor and stem cells. Here she found crucial differences, to be published Friday in Genes and Development.
Newborn ARTS-deprived mice had about twice as many hematopoietic stem cells as their normal, ARTS-endowed peers, and those stem cells were extraordinary in their ability to survive experimentally induced mutations.
"The increase in the number of hematopoietic progenitor and stem cells in Sept4-deficient mice brings with it the possibility of accelerating the accumulation of mutations in stem cells," says Garcia-Fernandez. "They have more stem cells with enhanced resistance to apoptosis. In the end, that leads to more cells accumulating mutations that cannot be eliminated."
Indeed, the ARTS-deprived mice developed spontaneous tumors at about twice the rate of their controls. "We make a connection between apoptosis, stem cells and cancer that has not been made in this way before: this pathway is critically important in stem cell death and in reducing tumor risk," Steller says. "The work supports the idea that the stem cell is the seed of the tumor and that the transition from a normal stem cell to a cancer stem cell involves increased resistance to apoptosis."
ARTS interferes with molecules called inhibitor of apoptosis proteins (IAPs), which prevent cells from killing themselves. By inhibiting these inhibitors, under the right circumstances ARTS helps to take the brakes off the process of apoptosis, permitting the cell to die on schedule. Pharmaceutical companies are working to develop small molecule IAP antagonists, but this research is the first to show that inactivating a natural IAP antagonist actually causes tumors to grow, Steller says. It also suggests that the premature silencing of the Sept4/ARTS pathway at the stem cell level may herald cancer to come.
"This work not only defines the role of the ARTS gene in the underlying mechanism of mammalian tumor cell resistance to programmed cell death, but also links this gene to another hallmark of cancer, stem and progenitor cell proliferation," said Marion Zatz, who oversees cell death grants, including Steller's, at the NIH's National Institute of General Medical Sciences. "The identification of the ARTS gene and its role in cancer cell death provides a potential target for new therapeutic approaches."
Brett Norman | EurekAlert!
Flavins keep a handy helper in their pocket
25.04.2018 | University of Freiburg
Complete skin regeneration system of fish unraveled
24.04.2018 | Tokyo Institute of Technology
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...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
25.04.2018 | Physics and Astronomy
25.04.2018 | Physics and Astronomy
25.04.2018 | Information Technology