Corporate Banner
Satellite Banner
Scientific Community
Become a Member | Sign in
Home>News>This Article

Protein Complex May Play Role in Preventing Many Forms of Cancer, Study Shows

Published: Tuesday, May 07, 2013
Last Updated: Tuesday, May 07, 2013
Bookmark and Share
Researchers at the Stanford University School of Medicine have identified a group of proteins that are mutated in about one-fifth of all human cancers.

The finding suggests that the proteins, which are members of a protein complex that affects how DNA is packaged in cells, work to suppress the development of tumors in many types of tissues.

The broad reach of the effect of mutations in the complex, called BAF, rivals that of another well-known tumor suppressor called p53. It also furthers a growing notion that these so-called chromatin-regulatory complexes may function as much more than mere cellular housekeepers.

"Although we knew that this complex was likely to play a role in preventing cancer, we didn't realize how extensive it would be," said postdoctoral scholar Cigall Kadoch, PhD. "It's often been thought that these complexes play supportive, maintenance-like roles in the cell. But this is really changing now."

Kadoch shares lead authorship of the study with postdoctoral scholar Diana Hargreaves, PhD. Gerald Crabtree, MD, professor of developmental biology and of pathology, is the senior author of the study, published online May 5 in Nature Genetics.

Chromatin-regulatory complexes work to keep DNA tightly condensed, while also granting temporary access to certain portions for replication or to allow the expression of genes necessary for the growth or function of the cell.

Members of Crabtree's laboratory have been interested in BAF complexes and their function for many years. Recently, they reported in the journal Nature that switching subunits within these complexes can convert human fibroblasts to neurons, which points to their instructive role in development and, possibly, cancer.

"Somehow these chromatin-regulatory complexes manage to compress nearly two yards of DNA into a nucleus about one one-thousandth the size of a pinhead," said Crabtree, who is also a member of the Stanford Cancer Institute and a Howard Hughes Medical Institute investigator. "And they do this without compromising the ability of the DNA to be replicated and selectively expressed in different tissues — all without tangling. In 1994 we reported that complexes of this type were likely to be tumor suppressors. Here we show that they are mutated in nearly 20 percent of all human malignancies thus far examined."

The researchers combined biochemical experiments with the data mining of 44 pre-existing studies to come to their conclusions, which would not have been possible without the advent of highly accurate, genome-wide DNA sequencing of individual human tumor samples. Interestingly, mutations to certain subunits, or particular combinations of mutations in the complex's many subunits, seem to herald the development of specific types of cancer — favoring the development of ovarian versus colon cancer, for example.

The importance of the BAF complex as a tumor suppressor is further emphasized by the fact that, in some cases, a mutation in one subunit is sufficient to initiate cancer development.

"For example," said Kadoch, "a type of mutation called a chromosomal translocation in the gene encoding one of these newly identified subunits, SS18, is known to be the hallmark of a cancer called synovial sarcoma. It is clearly the driving oncogenic event and very often the sole genomic abnormality in these cancers." Kadoch and Crabtree published a study in March in Cell uncovering the mechanism and functional consequences of BAF complex perturbation in synovial sarcoma.

The startling prevalence of mutations in the BAF complex was discovered when Kadoch conducted a series of experiments to determine exactly which proteins in the cell were true subunits of the complex. (The exact protein composition of the large complex varies among cell types and species.) Kadoch used an antibody that recognized one core component to purify intact BAF complexes in various cell types, including embryonic stem cells and skin, nerve and other cells. She then analyzed the various proteins isolated by the technique.

Using this method, Kadoch identified seven proteins previously unknown to be BAF components. She and Hargreaves then turned to previously published studies in which the DNA from a variety of human tumors had been sequenced to determine how frequently any of the members of the complex were mutated.

The results, once the newly discovered members were included, were surprising: 19.6 percent of all human tumors displayed a mutation in at least one of the complex's subunits. In addition, for some types of cancers (such as synovial sarcoma), every individual tumor sample examined had a mutation in a BAF subunit. The results suggest that the BAF complex, when unmutated, plays an important protective role against the development of cancer in many different tissues.

The researchers are now focused on learning how the mutations affect the tumor-suppressing activity of the BAF complex.

"We certainly want to further our understanding of the mechanism behind these findings," said Hargreaves. "Do they promote cancer development by inhibiting the proper progression of the cell cycle? Or perhaps they affect how the complex is positioned on the DNA. We'd like to determine how to recapitulate some of these mutations experimentally to see what types of defects they introduce into the complex."

Further Information
Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 2,800+ scientific posters on ePosters
  • More than 4,000+ scientific videos on LabTube
  • 35 community eNewsletters

Sign In

Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.

Related Content

New Class of RNA Tumor Suppressors Identified
Two short, “housekeeping” RNA molecules block cancer growth by binding to an important cancer-associated protein called KRAS. More than a quarter of all human cancers are missing these RNAs.
Thursday, November 26, 2015
Virus Re-Engineered to Deliver Targeted Therapies
Researchers stripped a virus of its infectious machinery and turned its benign core into a delivery vehicle that can target sick cells while leaving healthy tissue alone.
Thursday, September 24, 2015
Combination Drug Therapy Shrinks Pancreatic Tumors In Mice
Two drugs that affect the structure and function of DNA have been found to block the growth of pancreatic tumor cells in mice, researchers hope the drugs can soon be tested in humans with the disease.
Thursday, September 24, 2015
Long-sought Discovery Fills in Missing Details of Cell 'Switchboard'
A biomedical breakthrough reveals never-before-seen details of the human body’s cellular switchboard that regulates sensory and hormonal responses.
Monday, July 27, 2015
Existing Drug May Treat Deadliest Childhood Brain Tumor
For the first time, scientists have identified an existing drug that slows the growth of the deadliest childhood brain tumor.
Friday, May 08, 2015
Foreign Antibodies Mobilize Immune System to Fight Cancer
A mouse’s T cells can be primed to attack and eliminate a malignant tumor by injecting antibodies from another mouse with resistance to the tumor, as well as by activating certain signaling cells, a study has found.
Thursday, May 07, 2015
Tumor Suppressor Also Inhibits Key Property Of Stem Cells
The retinoblastoma protein inhibits cancer by controlling cell division. Now, researchers have shown that it also binds to and inhibits genes necessary for pluripotency.
Friday, November 14, 2014
Antibody Hinders Growth of Gleevec-Resistant Gastrointestinal Tumors in Lab Test
An antibody that binds to a molecule on the surface of a rare but deadly tumor of the gastrointestinal tract inhibits the growth of the cancer cells in mice.
Thursday, February 07, 2013
For Stanford Scientists, RNAi Gene Therapy Takes two Steps Forward, one Step Back
If RNAi is going to be viable as a therapy for organ-wide diseases such as hepatitis B or C, it will have to stick around.
Thursday, May 25, 2006
Scientific News
New Class of RNA Tumor Suppressors Identified
Two short, “housekeeping” RNA molecules block cancer growth by binding to an important cancer-associated protein called KRAS. More than a quarter of all human cancers are missing these RNAs.
Mathematical Model Forecasts the Path of Breast Cancer
Chances of survival depend on which organs breast cancer tumors colonize first.
Exploring the Causes of Cancer
Queen's research to understand the regulation of a cell surface protein involved in cancer.
Nanocarriers May Carry New Hope for Brain Cancer Therapy
Berkeley lab researchers develop nanoparticles that can carry therapeutics across the brain blood barrier.
RNA-Based Drugs Give More Control Over Gene Editing
CRISPR/Cas9 gene editing technique can be transiently activated and inactivated using RNA-based drugs, giving researchers more precise control in correcting and inactivating genes.
University of Glasgow Researchers Make An Impact in 60 Seconds
Early-career researchers were invited to submit an engaging, dynamic and compelling 60 second video illuminating an aspect of their research.
Metabolic Profiles Distinguish Early Stage Ovarian Cancer with Unprecedented Accuracy
Studying blood serum compounds of different molecular weights has led scientists to a set of biomarkers that may enable development of a highly accurate screening test for early-stage ovarian cancer.
Dead Bacteria to Kill Colorectal Cancer
Scientists from Nanyang Technological University (NTU Singapore) have successfully used dead bacteria to kill colorectal cancer cells.
CRISPR-Cas9 Gene Editing: Check Three Times, Cut Once
Two new studies from UC Berkeley should give scientists who use CRISPR-Cas9 for genome engineering greater confidence that they won’t inadvertently edit the wrong DNA.
Genetically Engineering Algae to Kill Cancer Cells
New interdisciplinary research has revealed the frontline role tiny algae could play in the battle against cancer, through the innovative use of nanotechnology.

Skyscraper Banner
Go to LabTube
Go to eposters
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
2,800+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
4,000+ scientific videos