Nav: Home

Normal tissues not so normal, but instead mosaics of mutated cells

June 06, 2019

Normal cell populations may not be as "normal" as once thought; rather, tissues contain lineages of mutational mosaics developed over a lifetime, according to a comprehensive RNA sequence analysis of more than 6,700 samples across 29 different human tissues. The study finds that somatic mutations - including genes associated with cancer risk - arise in virtually every type of normal tissue in the human body. What's more, the results indicate that sun-exposed skin, throat and lung tissues develop more mutations and suggest that environmental factors may promote somatic mutations. "Even the promise offered by cancer early detection methodologies via cell-free DNA critically depends on understanding what is normal and what is not," writes Cristian Tomasetti in a related Perspective, noting the significance of Yizhak et al.'s results on future cancer research. As people get older, they accumulate mutations in the healthy cells of normal tissues. Generally, these mutations amass passively with a negligible effect on cell behavior. However, mutant cells can become growing populations of harmful mutant clones, which are thought to be the origin of several diseases. While previous research has associated clonal expansions in normal tissues with cancer, an understanding of which specific clones could eventually lead to the development and progression of the disease remains unclear. To explore the mutational diversity of normal tissues, Keren Yizhak and colleagues developed a new method to detect mutational clones in normal tissues using RNA-sequencing (RNA-seq) data - a computational pipeline named RNA-MuTect. Unlike previous methods, it identified mutational clones in normal tissues for every expressed gene, rather than for just a small subset. Applying this method to RNA-seq data from both the Cancer Genome Atlas and the Genotype-Tissue Expression (GTEx) project, the authors identified clonal expansion in 37% of the tissue samples representing nearly all (95%) donor individuals. One third of individuals harbored mutations in genomic regions or genes known to play a causal role in cancer. The results show that a tissue's mutational burden is associated with age, cell proliferation rate and exposure to external mutagenic environmental factors.
-end-


American Association for the Advancement of Science

Related Cancer Articles:

Cancer mortality continues steady decline, driven by progress against lung cancer
The cancer death rate declined by 29% from 1991 to 2017, including a 2.2% drop from 2016 to 2017, the largest single-year drop in cancer mortality ever reported.
Stress in cervical cancer patients associated with higher risk of cancer-specific mortality
Psychological stress was associated with a higher risk of cancer-specific mortality in women diagnosed with cervical cancer.
Cancer-sniffing dogs 97% accurate in identifying lung cancer, according to study in JAOA
The next step will be to further fractionate the samples based on chemical and physical properties, presenting them back to the dogs until the specific biomarkers for each cancer are identified.
Moffitt Cancer Center researchers identify one way T cell function may fail in cancer
Moffitt Cancer Center researchers have discovered a mechanism by which one type of immune cell, CD8+ T cells, can become dysfunctional, impeding its ability to seek and kill cancer cells.
More cancer survivors, fewer cancer specialists point to challenge in meeting care needs
An aging population, a growing number of cancer survivors, and a projected shortage of cancer care providers will result in a challenge in delivering the care for cancer survivors in the United States if systemic changes are not made.
New cancer vaccine platform a potential tool for efficacious targeted cancer therapy
Researchers at the University of Helsinki have discovered a solution in the form of a cancer vaccine platform for improving the efficacy of oncolytic viruses used in cancer treatment.
American Cancer Society outlines blueprint for cancer control in the 21st century
The American Cancer Society is outlining its vision for cancer control in the decades ahead in a series of articles that forms the basis of a national cancer control plan.
Oncotarget: Cancer pioneer employs physics to approach cancer in last research article
In the cover article of Tuesday's issue of Oncotarget, James Frost, MD, PhD, Kenneth Pienta, MD, and the late Donald Coffey, Ph.D., use a theory of physical and biophysical symmetry to derive a new conceptualization of cancer.
Health indicators for newborns of breast cancer survivors may vary by cancer type
In a study published in the International Journal of Cancer, researchers from the UNC Lineberger Comprehensive Cancer Center analyzed health indicators for children born to young breast cancer survivors in North Carolina.
Few women with history of breast cancer and ovarian cancer take a recommended genetic test
More than 80 percent of women living with a history of breast or ovarian cancer at high-risk of having a gene mutation have never taken the test that can detect it.
More Cancer News and Cancer Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Teaching For Better Humans 2.0
More than test scores or good grades–what do kids need for the future? This hour, TED speakers explore how to help children grow into better humans, both during and after this time of crisis. Guests include educators Richard Culatta and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#556 The Power of Friendship
It's 2020 and times are tough. Maybe some of us are learning about social distancing the hard way. Maybe we just are all a little anxious. No matter what, we could probably use a friend. But what is a friend, exactly? And why do we need them so much? This week host Bethany Brookshire speaks with Lydia Denworth, author of the new book "Friendship: The Evolution, Biology, and Extraordinary Power of Life's Fundamental Bond". This episode is hosted by Bethany Brookshire, science writer from Science News.
Now Playing: Radiolab

Space
One of the most consistent questions we get at the show is from parents who want to know which episodes are kid-friendly and which aren't. So today, we're releasing a separate feed, Radiolab for Kids. To kick it off, we're rerunning an all-time favorite episode: Space. In the 60's, space exploration was an American obsession. This hour, we chart the path from romance to increasing cynicism. We begin with Ann Druyan, widow of Carl Sagan, with a story about the Voyager expedition, true love, and a golden record that travels through space. And astrophysicist Neil de Grasse Tyson explains the Coepernican Principle, and just how insignificant we are. Support Radiolab today at Radiolab.org/donate.