Scientists at The Wistar Institute offer a new explanation for the persistent ability of melanoma cells to self-renew, one of the reasons why melanoma remains the deadliest form of skin cancer. The concept of the “dynamic stemness” of melanoma can explain why melanoma cells behave like both conventional tumor cells and cancer stem cells.
The researchers write in the May 14 issue of the journal Cell that—contrary to other published reports—melanoma does not appear to follow the hierarchic cancer stem cell model, where a single malignant “mother cell” both reproduces to produce new mother cells and differentiates to produce the bulk tumor population. Instead, all melanoma cells equally harbor cancer stem cell potential and are capable of inducing new tumors. Their findings reveal the unique biology of melanoma, and suggest that melanoma requires a new therapeutic approach.
“Targeting only the bulk tumor population, as most conventional anticancer therapies do, is pointless in melanoma, in that each cell can act as a seed for the tumors to rebound,” said Meenhard Herlyn, D.V.M., D.Sc., professor and leader of Wistar’s Molecular and Cellular Oncogenesis Program. “The other implication is that we should stop hunting for a cancer stem cell, because it won’t be there.”
The traditional view of cancer holds that cancers arise following a random accumulation of malignant events, e.g. mutations, gradually imparting enough growth advantages that a cell can grow unchecked. Over the last decade, scientists have developed a cancer stem cell concept that explains how the slow growth and persistence of mother cells allow tumors to persist following treatment. Melanoma, for one, seems to follow a third path, dynamic stemness, where the stem cell-like behavior is not confined to mother cells alone, Herlyn says.
In the study, Herlyn and his colleagues describe a slow-growing subpopulation of melanoma tumor cells, defined by the protein JARID1B, which is required for tumor maintenance. Genetically blocking the ability of cells to express—or produce—this protein “exhausts” the tumor, preventing its proliferation. Yet unlike classic cancer stem cells, this subpopulation is highly plastic: JARID1B-expressing cells can turn off the gene, and JARID1B-non-expressing cells can turn it on.
Their findings suggest that melanoma requires a two-pronged therapeutic approach, says Herlyn. One is needed to target the bulk of the tumor, while another one should specifically target the slow-growing, JARID1B-positive subpopulation. “It’s a dual therapy that we are proposing,” said Herlyn.
According to the study’s lead author, Alexander Roesch, M.D., of the Regensburg University Medical Center in Germany and a visiting scientist in the Herlyn laboratory at The Wistar Institute, the growth could explain the disease’s notorious therapy resistance. “A slow-growing JARID1B-positive subpopulation of tumor cells, immune to most therapies, can spontaneously convert to a fast-growing JARID1B-negative population, which can rapidly replenish the tumor,” Roesch said.
The present study arose when Roesch discovered a link between the potential of JARID1B to decrease proliferation of melanoma cells and control stemness. He decided to see whether JARID1B could be a marker of slow growing melanoma stem cells. Initially, the results were promising, he says. JARID1B-expressing cells were slow-growing (as stem cells often are), and rare, accounting for about 5 percent of the tumor population. “At this point we were really happy because we thought we had found a cancer stem cell marker,” Roesch said.
But then, two unexpected results occurred. First, Roesch found that all melanoma cells were equally capable of initiating tumors in a mouse model, regardless of whether they expressed JARID1B or not. Second, he found that JARID1B expression did not conform to the traditional model of stem cell development – cells that expressed the gene could turn it off, and cells that didn’t, could turn it on. In other words, the gene’s expression was plastic, rather than stable. “Basically, our data suggest that every melanoma cell can serve as source for indefinite replenishment of the tumor,” said Roesch.
At the moment, the researchers do not suggest that the cancer stem cell model is wrong in any other tumors; their results apply only to melanoma, which may represent a special case.
Along with senior author Herlyn and first author Roesch, co-authors from the Herlyn laboratory include staff scientist Mizuho Fukunaga-Kalabis M.D., Ph.D.; post-doctoral fellows Susan E. Zabierowski, Ph.D., and Adina Vultur, Ph.D.; research technician Elizabeth C. Schmidt; research associate Patricia A. Brafford; and visting scientist Devraj Basu, M.D., Ph.D., of the University of Pennsylvania School of Medicine. Co-authors also include Phyllis Gimotty, Ph.D., of the University of Pennsylvania School of Medicine and Thomas Vogt, M.D., Regensburg University Medical Center.
The research was supported by grants from the US National Institutes of Health and the German Research Foundation.
The Wistar Institute is an international leader in biomedical research with special expertise in cancer research and vaccine development. Founded in 1892 as the first independent nonprofit biomedical research institute in the country, Wistar has long held the prestigious Cancer Center designation from the National Cancer Institute. The Institute works actively to ensure that research advances move from the laboratory to the clinic as quickly as possible. The Wistar Institute: Today’s Discoveries – Tomorrow’s Cures.
Greg Lester | Newswise Science News
Flow of cerebrospinal fluid regulates neural stem cell division
22.05.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Chemists at FAU successfully demonstrate imine hydrogenation with inexpensive main group metal
22.05.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg
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...
Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.
Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...
A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.
Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
18.05.2018 | Power and Electrical Engineering
18.05.2018 | Information Technology
18.05.2018 | Information Technology