Featured Research

from universities, journals, and other organizations

Key Mechanism That Occurs At Inception Point Of Many Human Lymphomas Identified

Date:
December 16, 2008
Source:
University of Southern California
Summary:
Researchers have explained how certain key mutations occur in human lymphomas -- a process that has, until now, remained a mystery.

Researchers at the Keck School of Medicine of the University of Southern California (USC) have explained how certain key mutations occur in human lymphomas—a process that has, until now, remained a mystery.

The findings of the study will have a significant impact on future study of how human lymphoma occurs.

Chromosomal translocations, in which segments of DNA are moved around the genome, are DNA mutations frequently found in blood cancers. They occur when two chromosomes break and the resulting fragments are reassembled in an exchange, says Michael R. Lieber, M.D/Ph.D., Rita and Edward Polusky Professor in Basic Cancer Research at the Keck School of Medicine and the study's principal investigator.

"Our study provides new insight into understanding how these translocations occur and describes a key and informative fingerprint at these chromosomal break sites," Lieber says.

The fingerprint had been overlooked for decades because chromosomal break sites typically suffer damage that obscures the fingerprint, he says.

"The precise steps leading to this pathologic rearrangement process—especially how the DNA is broken—have been a mystery for 25 years, in large part because these events occur long before the cancer becomes clinically apparent, and conventional experimental techniques do not reflect the process as it occurs naturally," says Albert Tsai, M.D/ Ph.D. candidate at the Keck School of Medicine and the lead author of the study.

Expanding on previous work done at the Keck School and USC Norris Comprehensive Cancer Center and elsewhere, researchers studied patient tumor chromosomal translocations to gain an important clue as to how the most common lymphomas are caused. The study demonstrated that these breaks are focused at CpG sites, short special sequences in the genome, within restricted breakage zones. The CpG localization occurs in early B-cells, but not in translocations before or after that stage.

Their findings implicated roles for two enzymes—AID and RAG complex—which are normally present in lymphocytes and that function to diversify the immune system to defend against attack by bacteria, viruses and parasites, Lieber says. The diversification process involves altering the DNA which encodes antibodies, by cutting and rejoining the DNA in a way that sometimes goes awry. This appears to be what causes the chromosomal translocations, he says.

"Based on previous clues, we did a number of biochemical studies to verify our hunch about the mechanism of translocation," Lieber says. "Our study demonstrates the biochemical feasibility of the sequence of events proposed, and this matches the fingerprint left by the chromosomal translocations."

The study relied on an important collaboration with Chih-Lin Hsieh, Ph.D., Catherine & Joseph Aresty Chair in Urologic Research at the Keck School of Medicine, and Markus Muschen, M.D., associate professor of pediatrics, biochemistry and molecular biology at the Keck School and director of the Leukemia Research Program at Childrens Hospital Los Angeles.

The study was funded by the National Cancer Institute and the National Institute of General Medical Sciences.


Story Source:

The above story is based on materials provided by University of Southern California. Note: Materials may be edited for content and length.


Journal Reference:

  1. Albert G. Tsai, Haihui Lu, Sathees C. Raghavan, Markus Muschen, Chih-Lin Hsieh and Michael R. Lieber. Human Chromosomal Translocations at CpG Sites and a Theoretical Basis for their Lineage and Stage Specificity. Cell, D-08-00489R3

Cite This Page:

University of Southern California. "Key Mechanism That Occurs At Inception Point Of Many Human Lymphomas Identified." ScienceDaily. ScienceDaily, 16 December 2008. <www.sciencedaily.com/releases/2008/12/081211141942.htm>.
University of Southern California. (2008, December 16). Key Mechanism That Occurs At Inception Point Of Many Human Lymphomas Identified. ScienceDaily. Retrieved July 30, 2014 from www.sciencedaily.com/releases/2008/12/081211141942.htm
University of Southern California. "Key Mechanism That Occurs At Inception Point Of Many Human Lymphomas Identified." ScienceDaily. www.sciencedaily.com/releases/2008/12/081211141942.htm (accessed July 30, 2014).

Share This




More Health & Medicine News

Wednesday, July 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Health Insurers' Profits Slide

Health Insurers' Profits Slide

Reuters - Business Video Online (July 30, 2014) Obamacare-related costs were said to be behind the profit plunge at Wellpoint and Humana, but Wellpoint sees the new exchanges boosting its earnings for the full year. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
Concern Grows Over Worsening Ebola Crisis

Concern Grows Over Worsening Ebola Crisis

AFP (July 30, 2014) Pan-African airline ASKY has suspended all flights to and from the capitals of Liberia and Sierra Leone amid the worsening Ebola health crisis, which has so far caused 672 deaths in Guinea, Liberia and Sierra Leone. Duration: 00:43 Video provided by AFP
Powered by NewsLook.com
At Least 20 Chikungunya Cases in New Jersey

At Least 20 Chikungunya Cases in New Jersey

AP (July 30, 2014) At least 20 New Jersey residents have tested positive for chikungunya, a mosquito-borne virus that has spread through the Caribbean. (July 30) Video provided by AP
Powered by NewsLook.com
Xtreme Eating: Your Daily Caloric Intake All On One Plate

Xtreme Eating: Your Daily Caloric Intake All On One Plate

Newsy (July 30, 2014) The Center for Science in the Public Interest released its 2014 list of single meals with whopping calorie counts. 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