Aggressive cancer exploits MYC oncogene to amplify global gene activity

September 27, 2012 by Nicole Giese Rura

Whitehead Institute researchers have determined the mechanism used by c-Myc to increase the expression of all active genes in cancer cells. Elevated levels of c-Myc are linked to increased rates of metastasis, disease recurrence, and mortality in cancer patients. Guided by this new model, researchers hope to find ways to restrict c-Myc's activity to eradicate cancer cells that become dependent on c-Myc for their survival.

For a cancer patient, over-expression of the oncogene is a bad omen.

Scientists have long known that in , elevated levels of MYC's protein product, c-Myc, are associated with poor clinical outcomes, including increased rates of metastasis, recurrence, and mortality. Yet decades of research producing thousands of scientific papers on the subject have failed to consistently explain precisely how c-Myc exerts its effects across a broad range of cancer types. Until now, that is.

The prevailing theory emerging from this massive body of research has been that in tumor cells, c-Myc affects the expression of specific genes or sets of genes—that so-called Myc are being selectively activated or repressed, leading to aberrant . Now, however, researchers in the lab of Whitehead Institute Member Richard Young are dispelling this commonly held notion, showing that elevated expression of c-Myc amplifies the activity of all expressed genes in tumor cells of multiple . It turns out that high levels of c-Myc send a tumor cell's program into overdrive. Transcription increases dramatically, allowing to overwhelm factors that might normally hamper their growth and proliferation. This surprising finding, published in this week's issue of the journal Cell, provides a simple, elegant explanation for how a single protein can have such profound effect in so many and varied . The newly revealed mechanism may also help scientists develop novel that disrupt c-Myc's activity.

"MYC is a key driver in most major cancers, but it has been notoriously difficult to drug," says Young, who is also a professor of biology at MIT. "Now that we know the mechanism by which c-Myc acts, we can go after the components of that mechanism as potential drug targets. This research creates an even stronger impetus to find a way to drug the thing."

One potential drawback to thwarting c-Myc's activity is the important role it plays in normal cell division. That role is so powerful that cells co-evolved an emergency death pathway to keep c-Myc expression in check. If c-Myc's production spins out of control in an otherwise normal cell, the cell immediately commits suicide through a process called apoptosis. But in in which c-Myc is overproduced, this suicide pathway is compromised, allowing the cell to survive and proliferate.

"MYC is the most deregulated gene in cancer," says Charles Lin, a graduate student in the Young lab and co-author of the Cell paper. "It's been called a bad-boy, a Swiss army knife, and a jack-of-all-trades because, according to previous research, it could do everything under the sun in a cancer cell. But most of the different attributes ascribed to MYC are contradictory or seemingly incompatible."

Propelled by its earlier research that identified c-Myc as an important regulator of transcription in embryonic stem cells, the Young lab began to focus on c-Myc's activity within cancer cells. Lab members found that as the expression of c-Myc increases in these cells, the protein attaches to the promoters and enhancers of all active genes, thereby amplifying the active genes' transcription. The heightened transcription produces cells bloated with excessive RNAs and proteins capable of altering normal cellular functions. Researchers observed this phenomenon in cells from a host of cancers, including Burkitt's lymphoma, small cell lung cancer, multiple myeloma, and glioblastoma multiforme.

"The previous research now makes sense – finally!" says Jakob Lovén, co-author and postdoctoral researcher in the Young lab. "Our findings provide a way to unify everybody's seemingly conflicting data. I think that's really nice. Instead of saying 'you're all wrong,' we're saying 'you're all right, and here's why.' The model makes a lot of sense in terms of the biology that has been described so far."

With a better understanding of how c-Myc can wreak so much damage, the Young lab is turning its efforts to disrupting c-Myc's activity. Although cancer cells that overproduce c-Myc are associated with poor clinical outcomes, their reliance on c-Myc for survival may represent an Achilles' heel. When these "Myc-addicted" cells are deprived of c-Myc in vitro, even for a short period of time, they quickly die. Research in mice has shown that, Myc-addicted tumors deprived of the protein shrink dramatically. Despite c-Myc's necessary role in normal cell division, particularly in tissues with rapid cell turnover, such as the intestine and blood, these mouse studies have shown that if c-Myc activity is restored after a brief period, normal tissues quickly bounce back, while tumors are unable to regain their footing.

"So what we think now is that potentially, if drugs can tune down the levels of transcription just slightly, this might be catastrophic for the Myc-addicted cancer cells," says Peter Rahl, co-author and postdoctoral researcher in the Young lab. "You wouldn't need to abolish all transcription because that would be toxic to your other cells. So we're hoping that our model will show us ways to create a therapeutic window where the Myc-addicted just won't be able to adapt to lower levels of transcripts."

Explore further: Lymphoma therapy could deliver a double punch

More information: "Transcriptional Amplification in Tumor Cells with Elevated c-Myc" Cell, September 28, 2012, in print.

Related Stories

Lymphoma therapy could deliver a double punch

April 30, 2012
B cell lymphomas are a group of cancers of that originate in lymphoid tissue from B cells, the specialized immune cell type that produces antibodies. The development of B cell lymphoma is associated with several known genetic ...

Scientists identify a critical tumor suppressor for cancer

August 2, 2012
Scientists from the Florida campus of The Scripps Research Institute have identified a protein that impairs the development and maintenance of lymphoma (cancer of the lymph nodes), but is repressed during the initial stages ...

Protein may represent a switch to turn off B cell lymphoma

May 7, 2012
Researchers studying the molecular signals that drive a specific type of lymphoma have discovered a key biological pathway leading to this type of cancer. Cancerous cells have been described as being "addicted" to certain ...

Novel approach scores first success against elusive cancer gene

September 9, 2011
Dana-Farber Cancer Institute scientists have successfully disrupted the function of a cancer gene involved in the formation of most human tumors by tampering with the gene's "on" switch and growth signals, rather than targeting ...

Recommended for you

Vitamin C may encourage blood cancer stem cells to die

August 17, 2017
Vitamin C may "tell" faulty stem cells in the bone marrow to mature and die normally, instead of multiplying to cause blood cancers. This is the finding of a study led by researchers from Perlmutter Cancer Center at NYU Langone ...

Outdoor light at night linked with increased breast cancer risk in women

August 17, 2017
Women who live in areas with higher levels of outdoor light at night may be at higher risk for breast cancer than those living in areas with lower levels, according to a large long-term study from Harvard T.H. Chan School ...

Scientists develop novel immunotherapy technology for prostate cancer

August 17, 2017
A study led by scientists at The Wistar Institute describes a novel immunotherapeutic strategy for the treatment of cancer based on the use of synthetic DNA to directly encode protective antibodies against a cancer specific ...

Toxic formaldehyde is produced inside our own cells, scientists discover

August 16, 2017
New research has revealed that some of the toxin formaldehyde in our bodies does not come from our environment - it is a by-product of an essential reaction inside our own cells. This could provide new targets for developing ...

Cell cycle-blocking drugs can shrink tumors by enlisting immune system in attack on cancer

August 16, 2017
In the brief time that drugs known as CDK4/6 inhibitors have been approved for the treatment of metastatic breast cancer, doctors have made a startling observation: in certain patients, the drugs—designed to halt cancer ...

Researchers find 'switch' that turns on immune cells' tumor-killing ability

August 16, 2017
Molecular biologists led by Leonid Pobezinsky and his wife and research collaborator Elena Pobezinskaya at the University of Massachusetts Amherst have published results that for the first time show how a microRNA molecule ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.