The Massachusetts General Hospital (MGH) research team that first discovered tumor-associated RNA in tiny membrane-enclosed sacs released into the bloodstream by cancer cells has now found that these microvesicles also contain segments of tumor DNA, including retrotransposons – also called "jumping genes" – that copy and insert themselves into other areas of the genome. The investigators' report, which has been published in Nature Communications, is the first to show that microvesicles are involved in transferring retrotransposons between cells.
"Retrotransposons' action of self-copying and reinserting themselves into the genome leads to genetic instability," says Johan Skog, PhD, who led the current study while an investigator in the MGH Neurology Service. "Many researchers have proposed this as a mechanism for genetic diversity and for evolution. Retrotransposons are known to be upregulated in cancer, and discovering them in microvesicles that can be found in all body fluids suggests they could be useful biomarkers to help understand tumor progression and monitor treatment response."
Skog was lead author of a 2008 study that first identified tumor-associated RNA in microvesicles, also called exosomes, released by the deadly adult brain tumor glioblastoma. To further investigate the ability of microvesicles to reflect the genetic status of tumors, in the current study the MGH team analyzed the nucleic acid contents of microvesicles from glioblastomas, from two types of pediatric brain tumors, and from malignant melanomas.
They found that the microvesicles contained tumor DNA as well as RNA and that microvesicles from one of the pediatric tumors studied had elevated levels of both DNA and RNA from the oncogene c-Myc, which correlated with the gene's expression in that tumor. "We showed that amplification of c-Myc was present in microvesicles whenever it was present in the donor cell and that microvesicle analysis can reveal oncogene expression in the original tumor," explains Leonora Balaj of MGH Neurology, the first author of the study.
High levels of retrotransposon-associated RNA sequences were also detected in tumor microvesicles, and the investigators found those microvesicles could transfer their contents into normal cells. "One of the most important functions of tumor-derived microvesicles may be modification of normal cells in the microenvironment to make them more supportive of tumor growth," says study co-author Xandra Breakefield, PhD, MGH Neurology and a professor of Neurology at Harvard Medical School.
Skog is now the director of research for Exosome Diagnostics, the company that licensed the work described in the 2008 paper, and continues to consult with Breakefield's research team. Additional co-authors of the Nature Communications report are Ryan Lessard, MGH Neurology; Lixin Dai, Johns Hopkins School of Medicine; and Yoon-Jae Cho, MD, and Scott Pomeroy, MD, PhD, Children's Hospital Boston. The study was supported by grants from the National Cancer Institute, the Wenner-Gren Foundation, and Stiftelsen Olle Engkvist Byggmastare.
Celebrating the 200th anniversary of its founding in 1811, Massachusetts General Hospital is the original and largest teaching hospital of Harvard Medical School. The MGH conducts the largest hospital-based research program in the United States, with an annual research budget of nearly $700 million and major research centers in AIDS, cardiovascular research, cancer, computational and integrative biology, cutaneous biology, human genetics, medical imaging, neurodegenerative disorders, regenerative medicine, systems biology, transplantation biology and photomedicine.
Sue McGreevey | EurekAlert!
Cells communicate in a dynamic code
19.02.2018 | California Institute of Technology
Studying mitosis' structure to understand the inside of cancer cells
19.02.2018 | Biophysical Society
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...
Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...
Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters
Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
19.02.2018 | Materials Sciences
19.02.2018 | Materials Sciences
19.02.2018 | Life Sciences