Featured Research

from universities, journals, and other organizations

Low Dose Radiation Evades Cancer Cells' Protective 'Radar'

Date:
October 6, 2004
Source:
Johns Hopkins Medical Institutions
Summary:
A new study shows that lower doses of radiation elude a damage detection "radar" in DNA and actually kill more cancer cells than high-dose radiation. With these findings, scientists believe they can design therapy to dismantle this "radar" sensor allowing more radiation to evade detection and destroy even greater numbers of cancer cells.

A new study shows that lower doses of radiation elude a damage detection "radar" in DNA and actually kill more cancer cells than high-dose radiation. With these findings, scientists believe they can design therapy to dismantle this "radar" sensor allowing more radiation to evade detection and destroy even greater numbers of cancer cells.

Researchers at the Johns Hopkins Kimmel Cancer Center tested the low-dose radiation strategy on cultured prostate and colon cancer cell lines and found that it killed up to twice as many cells as high-dose radiation. The extra lethality of the low-dose regimen was found to result from suppression of a protein, called ATM* which works like a radar to detect DNA damage and begin repair.

Theodore DeWeese, M.D., who led the study, speculates that cells hit with small amounts of radiation fail to switch on the ATM radar, which prevents an error-prone repair process. DeWeese, who will present his evidence at the annual meeting of the American Society for Therapeutic Radiology and Oncology on October 5 in Atlanta, explains.

"DNA repair is not foolproof - it can lead to mistakes or mutations that are passed down to other generations of cells," explains DeWeese, chairman of the Department of Radiation Oncology and Molecular Radiation Sciences at Johns Hopkins. "A dead cell is better than a mutant cell, so if the damage is mild, cells die instead of risking repair."

Higher doses of radiation cause extreme DNA damage and widespread cell death, so the ATM damage sensor is activated to preserve as many cells as possible, protecting, ironically, the cancer cells under target for destruction by the radiation.

While the low-dose regimen works in cultured cells, it has not proved successful in humans. This has lead to effort by Hopkins scientists to study ways to use viruses that can deliver ATM-blocking drugs to the cells. Tests in animals are expected to begin soon.

In the current study, colon and prostate cancer cells lines were treated with either high levels of radiation or small amounts spread over many days. Low-level radiation is approximately 10 times more powerful than normal exposure, while high doses are 1,000 times stronger. Approximately 35 percent of colon cancer cells survived low-dose radiation as compared to 60 percent receiving high-dose. In prostate cancer cell lines, half of the cells survived low-dose radiation, while 65 percent remained in higher doses.

In the low-dose group, ATM activation was reduced by 40 to 50 percent. The researchers proved ATM inactivation was the culprit since low-dose irradiated cells fared better after ATM was reactivated with chloroqine, best known as a treatment for malaria.

"Tricking cancer cells into ignoring the damage signals that appear on its radar could succeed in making radiation more effective in wiping out the disease," says DeWeese.

This research was funded by the National Cancer Institute.

Research participants from Johns Hopkins include Spencer Collis, Julie Schwaninger, Alfred Ntambi, Thomas Keller, Larry Dillehay, and William Nelson.


Story Source:

The above story is based on materials provided by Johns Hopkins Medical Institutions. Note: Materials may be edited for content and length.


Cite This Page:

Johns Hopkins Medical Institutions. "Low Dose Radiation Evades Cancer Cells' Protective 'Radar'." ScienceDaily. ScienceDaily, 6 October 2004. <www.sciencedaily.com/releases/2004/10/041006084356.htm>.
Johns Hopkins Medical Institutions. (2004, October 6). Low Dose Radiation Evades Cancer Cells' Protective 'Radar'. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2004/10/041006084356.htm
Johns Hopkins Medical Institutions. "Low Dose Radiation Evades Cancer Cells' Protective 'Radar'." ScienceDaily. www.sciencedaily.com/releases/2004/10/041006084356.htm (accessed July 28, 2014).

Share This




More Health & Medicine News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Trees Could Save More Than 850 Lives Each Year

Trees Could Save More Than 850 Lives Each Year

Newsy (July 27, 2014) A national study conducted by the USDA Forest Service found that trees collectively save more than 850 lives on an annual basis. Video provided by Newsy
Powered by NewsLook.com
Google's Next Frontier: The Human Body

Google's Next Frontier: The Human Body

Newsy (July 27, 2014) Google is collecting genetic and molecular information to paint a picture of the perfectly healthy human. Video provided by Newsy
Powered by NewsLook.com
What's To Blame For Worst Ebola Outbreak In History?

What's To Blame For Worst Ebola Outbreak In History?

Newsy (July 27, 2014) A U.S. doctor has tested positive for the deadly Ebola virus, as the worst-ever outbreak continues to grow. Video provided by Newsy
Powered by NewsLook.com
Losing Sleep Leaves You Vulnerable To 'False Memories'

Losing Sleep Leaves You Vulnerable To 'False Memories'

Newsy (July 27, 2014) A new study shows sleep deprivation can make it harder for people to remember specific details of an event. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins