Featured Research

from universities, journals, and other organizations

Calorie Restriction And Exercise Show Breast Cancer Prevention Differences In Postmenopausal Women

Date:
November 21, 2008
Source:
American Association for Cancer Research
Summary:
Scientists have identified pathways by which a reduced-calorie diet and exercise can modify a postmenopausal woman's risk of breast cancer.

Scientists at the University of Texas at Austin have identified pathways by which a reduced-calorie diet and exercise can modify a postmenopausal woman's risk of breast cancer.

The results, presented at the American Association for Cancer Research's Seventh Annual International Conference on Frontiers in Cancer Prevention Research, suggest that both caloric restriction and exercise affect pathways leading to mTOR, a molecule involved in integrating energy balance with cell growth. Dysregulation of the mTOR pathway is a contributing factor to various human diseases, including cancers. Diet and exercise reach mTOR through different means, with calorie restriction affecting more upstream pathways, which could explain why caloric restriction is more efficient in delaying tumor growth than exercise in animal models.

"One of the few breast cancer modifiable risk factors is obesity," said lead author Leticia M. Nogueira, Ph.D., a research graduate assistant at the University of Texas. "Our study may provide a good scientific basis for medical recommendations. If you're obese, and at high risk for breast cancer, diet and exercise could help prevent tumor growth."

Epidemiological data has suggested that inducing a so-called "negative energy balance" (where less energy is taken in than expended) through eating a low-calorie diet or increasing exercise levels, decreases the postmenopausal breast cancer risk associated with obesity. Although the mechanism responsible for these anti-obesity strategies was unknown, scientists have suspected hormone alteration plays a critical role. Increased fat tissue is known to be associated with alterations in adipokines, proteins secreted by fat tissue that help modify appetite and insulin resistance. For example, increased levels of leptin and decreased levels of adiponectin have been associated with breast cancer risk.

For the study, Nogueira and colleagues sought to compare the changes in adipokines, and their downstream signaling pathways proven to be altered in human breast cancers, following either caloric restriction or exercise in a mouse model of post-menopausal obesity.

For eight weeks, they administered a high-fat diet to 45 mice that had their ovaries surgically removed to model the post-menopausal state. During week nine of the study, the diet-induced obese mice were randomly assigned to one of three groups: a control group, permitted to eat at will; a group fed a diet reduced in calories by 30 percent; and a group that was permitted to eat at will but exercised on a treadmill for 45 minutes a day, five days a week. At week 16, researchers collected tissue from the mice for analysis.

At the study's end, the mice fed a calorie-restricted diet weighed an average of 19.9 grams – significantly less than the control mice (average weight 28.8 grams) and the exercised mice (average weight 26 grams). The calorie-restricted mice and the exercised mice showed no significant difference in percentage of body fat, but both groups had significantly less body fat than the sedentary mice that were fed at will.

In addition, blood levels of leptin, a hormone that plays a role in fat metabolism, were significantly reduced in the calorie-restricted and exercised mice compared to the controls. The calorie-restricted mice also displayed increased blood levels of adiponectin, a hormone produced in fat tissue that regulates some metabolic processes, compared to the exercised mice.

Some of the cell signaling pathways regulated by these hormones converge at mTOR, Nogueira explains. She and her colleagues found that the key proteins found downstream of mTOR activation were less active in both the calorie-restricted and exercised mice compared to the controls.

"These data suggest that although exercise can act on similar pathways as caloric restriction, caloric restriction possesses a more global effect on cell signaling and, therefore, may produce a more potent anti-cancer effect," Nogueira said.


Story Source:

The above story is based on materials provided by American Association for Cancer Research. Note: Materials may be edited for content and length.


Cite This Page:

American Association for Cancer Research. "Calorie Restriction And Exercise Show Breast Cancer Prevention Differences In Postmenopausal Women." ScienceDaily. ScienceDaily, 21 November 2008. <www.sciencedaily.com/releases/2008/11/081118150628.htm>.
American Association for Cancer Research. (2008, November 21). Calorie Restriction And Exercise Show Breast Cancer Prevention Differences In Postmenopausal Women. ScienceDaily. Retrieved April 17, 2014 from www.sciencedaily.com/releases/2008/11/081118150628.htm
American Association for Cancer Research. "Calorie Restriction And Exercise Show Breast Cancer Prevention Differences In Postmenopausal Women." ScienceDaily. www.sciencedaily.com/releases/2008/11/081118150628.htm (accessed April 17, 2014).

Share This



More Health & Medicine News

Thursday, April 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Could Even Casual Marijuana Use Alter Your Brain?

Could Even Casual Marijuana Use Alter Your Brain?

Newsy (Apr. 16, 2014) A new study conducted by researchers at Northwestern and Harvard suggests even casual marijuana use can alter your brain. Video provided by Newsy
Powered by NewsLook.com
Thousands Of Vials Of SARS Virus Go Missing

Thousands Of Vials Of SARS Virus Go Missing

Newsy (Apr. 16, 2014) A research institute in Paris somehow misplaced more than 2,000 vials of the deadly SARS virus. Video provided by Newsy
Powered by NewsLook.com
Formerly Conjoined Twins Released From Dallas Hospital

Formerly Conjoined Twins Released From Dallas Hospital

Newsy (Apr. 16, 2014) Conjoined twins Emmett and Owen Ezell were separated by doctors in August. Now, nearly nine months later, they're being released from the hospital. Video provided by Newsy
Powered by NewsLook.com
Ebola Outbreak Now Linked To 121 Deaths

Ebola Outbreak Now Linked To 121 Deaths

Newsy (Apr. 15, 2014) The ebola virus outbreak in West Africa is now linked to 121 deaths. Health officials fear the virus will continue to spread in urban areas. 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