Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Timing of radiation treatments for colon cancer may need adjusting

10.04.2006


Scientists have unexpectedly discovered that mice with the gene defect that causes colon cancer in humans can differ from normal mice in how they respond to radiation treatments. The large intestine carrying the gene defect in mice that received staggered doses of radiation was three to four times more resistant to the radiation than in control mice.



The researchers, led by Bruce Boman, M.D., Ph.D., director of the Division of Genetic and Preventive Medicine at Jefferson Medical College of Thomas Jefferson University in Philadelphia and at Jefferson’s Kimmel Cancer Center and Dennis Leeper, Ph.D., professor of radiation oncology at Jefferson Medical College, say these results may have implications for treating patients with colon cancer, which is a tumor that frequently has mutations in a gene called APC.

They reported their findings this week at the 2006 annual meeting of the American Association for Cancer Research in Washington, D.C. (Stem Cell Number and Radiation Resistance During Repair in Colonic Crypts of APC Mice: Abstract no. LB-311).


Scientists have known that patients’ colon tumors with APC mutations have an increased amount of survivin, a protein that halts the process of programmed cell death. This increase also appears to be associated with a rise in the number of stem cells that sit at the bottom of colonic crypts, tube-like structures that make up the lining of the intestine. Drs. Leeper and Boman wanted to see if there was a difference in stem cell number between normal mice and mice that carry a mutation in APC. To do this, they exposed both normal and mutant mice to radiation, testing their ability to repair the resulting DNA damage. They speculated that increased survivin in the mutant mice might enable more stem cells to survive and affect the response to radiation. The researchers asked if mice with an APC mutation, making them prone to develop colon cancer, are different from normal mice in radiation sensitivity and their ability to repair the damage. Normal cells can repair DNA damage from radiation, Dr. Leeper explains.

They measured the survival of colon crypts in the small and large intestines in normal and mutant mice following radiation exposure, looking at the responses to both single doses of radiation and to staggered or "fractionated" doses of radiation, where the second dose is given five hours after the first dose, again causing the DNA repair to kick in.

"In the normal mouse the radiation-induced damage in the intestine is repaired, just as we expected," Dr. Boman explains. In fact, intestinal cells in both the mutant mouse and normal mouse reacted the same to the single dose of radiation.

But the mutant mice responded differently to the staggered radiation. "When we irradiate five hours later when repair has begun, and damage is being repaired, and then a second dose of radiation is given, the mutant mice are resistant," says Dr. Leeper. More specifically, the Jefferson team found that in the large intestine in the mutant mice, the colon crypt cells were more resistant to radiation by a factor of three to four.

"This has never been observed before to my knowledge," Dr. Leeper says. "This is a novel finding." He notes that the results could have important implications as to how radiation is given to colon cancer patients. "If you are giving radiation once a day, it shouldn’t be a problem. But if you are fractionating treatments, given it two or three times a day, this finding could have implications. We would want to make sure that repair processes and signaling receptors come back to baseline before a second dose of chemotherapy is given."

Steve Benowitz | EurekAlert!
Further information:
http://www.jefferson.edu

More articles from Health and Medicine:

nachricht Study tracks inner workings of the brain with new biosensor
16.08.2018 | Rheinische Friedrich-Wilhelms-Universität Bonn

nachricht Foods of the future
15.08.2018 | Georg-August-Universität Göttingen

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: It’s All in the Mix: Jülich Researchers are Developing Fast-Charging Solid-State Batteries

There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.

The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Quantum bugs, meet your new swatter

20.08.2018 | Information Technology

A novel synthetic antibody enables conditional “protein knockdown” in vertebrates

20.08.2018 | Life Sciences

Metamolds: Molding a mold

20.08.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>