RELEVANCE: These findings may redefine how researchers view cancer stem cells – the cells capable of seeding new tumors at primary and distant sites in the body. Therapies that specifically target cancer stem cells are currently being investigated in the belief that eliminating cancer stem cells could prevent tumor recurrence and metastasis.
However, if cancerous, more differentiated cells can switch between the differentiated and stem-cell states, the more differentiated cancer cells might provide an endless source of new cancer stem cells. In the longer term, the observed behavior may also hold promise for degenerative disease therapy by allowing the derivation of patient specific adult stem cells without genetically altering such cells.
Whitehead Institute researchers have discovered that a differentiated cell type found in breast tissue can spontaneously convert to a stem-cell-like state, the first time such behavior has been observed in mammalian cells. These results refute scientific dogma, which states that differentiation is a one-way path; once cells specialize, they cannot return to the flexible stem-cell state on their own.
This surprising finding, published online this week in the Proceedings of the National Academy of Sciences (PNAS), may have implications for the development of cancer therapeutics, particularly those aimed at eradicating cancer stem cells.
"It may be that if one eliminates the cancer stem cells within a tumor through some targeted agent, some of the surviving non-stem tumor cells will generate new cancer stem cells through spontaneous de-differentiation," says Whitehead Founding Member Robert Weinberg. Cancer stem cells are uniquely capable of reseeding tumors at both primary and distant sites in the body.
During differentiation, less-specialized stem cells mature into many different cell types with defined functions. These differentiated cells work together to form tissues and organs. In breast tissue, for example, differentiated basal cells and luminal cells combine to form milk ducts.
While analyzing cells from human breast tissue, Christine Chaffer, who is a postdoctoral researcher in the Weinberg lab and first author of the PNAS paper, observed a small number of living basal cells floating freely in the tissue culture medium.
Intrigued by the cells' unusual behavior, Chaffer conducted further targeted investigations, including injection of the floating basal cells into mice. After 12 weeks she found that the injected basal cells gave rise to milk duct-like structures containing both basal and luminal cells—a clear indication that the floating cells had de-differentiated into stem-like cells.
Until now, no one has shown that differentiated mammalian cells, like these basal cells, have the ability to spontaneously revert to the stem-like state (a behavior described as plasticity).
To see if basal cells could become cancer stem cells, Chaffer inserted cancer-causing genes into the cells. When these transformed cells were injected into mice, the resulting tumors were found to include a cancer stem cell population that descended from the original injected basal (more differentiated) cells. These results indicate that basal cells in breast cancer tumors can serve as a previously unidentified source of cancer stem cells.
As research for new cancer therapies has recently focused on eliminating cancer stem cells, Weinberg cautions that the plasticity seen in these basal cells suggests a more complicated scenario than previously thought.
"Future drug therapies that are targeted against cancer will need to eliminate the cancer stem cells and, in addition, get rid of the non-stem cells in tumors – both populations must be removed," says Weinberg, who is also a professor of biology at MIT. "Knocking out one or the other is unlikely to suffice to generate a durable clinical response."
Chaffer is now focusing on what actually prompts these flexible cells to de-differentiate, and in the case of cancer cells, how to stop the cells from converting into cancer stem cells.
"This plasticity can occur naturally, and it seems that the trigger may be a physiological mechanism for restoring a pool of stem cells," says Chaffer. "We believe that certain cells are more susceptible to such a trigger and therefore to conversion from a differentiated to a stem-like state, and that this process occurs more frequently in cancerous cells."
In the case of normal epithelial cells, the observed behavior may also allow patient specific adult stem cells to be derived without genetic manipulation, holding promise for degenerative disease therapy.
This research was supported by the National Health and Medical Research Council of Australia, National Institutes of Health (NIH), Massachusetts Institute of Technology's Ludwig Center for Molecular Oncology, the Breast Cancer Research Foundation, and a Department of Defense (DoD) Breast Cancer Research Program (BCRP) Idea Award.
Written by Nicole Giese
Robert Weinberg's primary affiliation is with Whitehead Institute for Biomedical Research, where his laboratory is located and all his research is conducted. He is also a professor of biology at Massachusetts Institute of Technology and Director of the MIT/Ludwig Center for Molecular Oncology.
Full Citation: "Normal and neoplastic nonstem cells can spontaneously convert to a stem-like state" Christine L. Chaffer (1,2), Ines Brueckmann (1), Christina Scheel (1,2), Alicia J. Kaestli (1), Paul A. Wiggins (1), Leonardo O. Rodrigues (1,2), Mary Brooks(1,2), Ferenc Reinhardt (1,2), Ying Su (3), Kornelia Polyak (3), Lisa M. Arendt (4,5), Charlotte Kuperwasserd (5), Brian Bierie (1,2), and Robert A. Weinberg (1,2,6)1. Whitehead Institute for Biomedical Research, Cambridge, MA 02142
6. Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
Nicole Giese | EurekAlert!
Building a brain, cell by cell: Researchers make a mini neuron network (of two)
23.05.2018 | Institute of Industrial Science, The University of Tokyo
Research reveals how order first appears in liquid crystals
23.05.2018 | Brown University
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
23.05.2018 | Life Sciences
23.05.2018 | Life Sciences
23.05.2018 | Physics and Astronomy