Cells generated from the pituitary tumor cells had the same genetic makeup and characteristics as the original tumors and were capable of generating new tumors, according to an article in the July 2009 issue of the British Journal of Cancer, posted online June 30.
Normal stem cells have the ability to self-renew and the potential to "differentiate" into any of several types of cells. Tumor stem-like cells appear to have the same self-renewing and multipotent properties, but instead of producing healthy cells, they propagate tumor cells. In this study, benign tumor stem-like cells were analyzed for their genetic makeup and behavior.
Pituitary adenomas have unusual characteristics that provided significant clues about several types of stem cells. The pituitary gland, situated at the base of the brain behind the nose, is stimulated by hormones from the hypothalamus gland to produce a variety of hormones that control other glands throughout the body. About half of all pituitary adenomas – which arise from pituitary gland tissue – also have this hormone-producing capability.
In these studies, the scientists isolated stem-like cells from both hormone-producing and non-producing pituitary adenomas that had been surgically removed from eight patients. Laboratory experiments focused on tumor stem cells from one tumor that produced growth hormone and one tumor that produced no hormones. Both types of stem-like cells were found to be self-renewable and multipotent, meaning they expressed proteins that could enable their offspring to differentiate into several types of cells.
Studies also showed that both hormone-producing and non-producing tumor stem cells can be differentiated into hormone-producing cells, with the specific hormones produced being determined by the characteristics of the original pituitary tumor.
Consistent with the researchers' earlier findings in cancer stem-like cells of malignant brain tumors, the tumor stem cells – but not the "daughter" cells – appeared to be resistant to chemotherapy. This suggests that even if most of a tumor's cells can be killed, stem-like cells may survive and regenerate the tumor.
When tumor stem-like cells were implanted into laboratory mice, they generated new tumors that had the same genetic composition and characteristics as the original tumors. Cells from the new tumors, later transplanted into other mice, maintained the same tumor-specific properties.
"Although previous studies have offered evidence of the existence of stem-like cells in pituitary adenomas, in this study we scrutinized these cells for composition and function, demonstrating that stem-like cells exist in benign tumors," said neurosurgeon John S. Yu, M.D., director of Surgical Neuro-oncology at Cedars-Sinai Medical Center. He is senior author of the journal article.
Although pituitary adenomas are typically noncancerous, they can cause significant injury or illness, either by compressing important structures, such as the optic nerve, or by creating hormone imbalances that can have wide-ranging and serious consequences. Identifying the mechanisms that enable these and other tumors to form may provide unique targets for new, more effective therapies.
"From our work with cancer stem-like cells in malignant brain cancers, it appears that stem cells from different cancers – or possibly even within the same tumor – may use different signaling pathways and have different implications for disease progression and prognosis. Findings from the pituitary tumor study generally support the cancer stem cell hypothesis, suggesting that similar mechanisms may be involved in the generation of both malignant and benign tumors," said Keith L. Black, M.D., chairman of the Department of Neurosurgery at Cedars-Sinai.
"Confirmation of the existence of stem-like cells in benign tumors is intriguing," said Yu, "but many questions remain to be answered, particularly in defining the molecular mechanisms involved. We need to find out if there is any relationship between tumor stem cells and normal pituitary stem cells, and how stem cells from benign tumors are different from and similar to those of malignant tumors."
Research scientists from Cedars-Sinai's departments of Neurosurgery, Pathology and Laboratory Medicine, and Surgery participated in these studies, which were partly funded by the National Institutes of Health (NIH) and the Italian Association for Neurological Research (ARIN).
Citation: British Journal of Cancer: "Isolation of tumour stem-like cells from benign tumours." July 2009: http://www.nature.com/bjc/journal/v101/n2/abs/6605142a.html
Sandy Van | EurekAlert!
Bacteria as pacemaker for the intestine
22.11.2017 | Christian-Albrechts-Universität zu Kiel
Researchers identify how bacterium survives in oxygen-poor environments
22.11.2017 | Columbia University
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
22.11.2017 | Business and Finance
22.11.2017 | Physics and Astronomy
22.11.2017 | Physics and Astronomy