Polyunsaturated fat

[Guest guest]

Statement from the Article below:

" consuming high amounts of polyunsaturated fat may increase the risk of cancer

spreading "

can anyone comment about this statement?

thanks

karla

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Excessive Dietary Fat Caused 300 Percent Increase in Metastasizing Tumor Cells

In Animal Models

ScienceDaily (Feb. 26, 2009) — Researchers at Purdue University have precisely

measured the impact of a high-fat diet on the spread of cancer, finding that

excessive dietary fat caused a 300 percent increase in metastasizing tumor cells

in laboratory animals.

The researchers used an imaging technique to document how increasing fat content

causes cancer cells to undergo changes essential to metastasis. Then they used

another technique to count the number of cancer cells in the bloodstream of mice

fed a high-fat diet compared to animals fed a lean diet.

The findings suggest that the combined tools represent a possible new diagnostic

technique to determine whether a patient's cancer is spreading, said Ji-Xin

Cheng, an assistant professor in Purdue's Weldon School of Biomedical

Engineering and Department of Chemistry.

" It is generally accepted that diet and obesity are accountable for 30 percent

of preventable causes of cancer, but nobody really knows why, " Cheng said.

" These findings demonstrate that an increase in lipids leads directly to a rise

in cancer metastasis. "

Researchers have theorized that tumor cells need more lipids than ordinary

tissues to provide energy and material for tumor growth and metastasis.

" Before this work, however, most of the evidence was anecdotal, but here we

present a mechanistic study, " said Thuc T. Le, a National Institutes of Health

postdoctoral fellow at Purdue who is working with Cheng.

Findings were detailed in a paper published on Jan. 30 in the journal BMC

Cancer. The paper was written by Le; Terry B. Huff, a graduate research

assistant in Purdue's Department of Chemistry; and Cheng. The research is

supported by the Purdue Cancer Center.

The researchers implanted a cancerous lung tumor under the skin in each of the

mice studied, and the animals were separated into two groups: one fed a high-fat

diet and the other a lean diet.

The researchers then used an imaging method called coherent anti-Stokes Raman

scattering, or CARS, to document how increasing lipids from fat intake induces

changes to cancer cell membranes. Those changes, including processes called

membrane phase separation and membrane rounding, enhance cancer metastasis.

" If the cancer cells don't have excess lipids they stick together and form very

tight junctions in tumors, but increasing lipids causes them to take on a

rounded shape and separate from each other, " Le said.

The change in shape is critical to the ability of cancer cells to separate and

spread throughout the body via the bloodstream.

The researchers then used another technique, called intravital flow cytometry,

to count the number of cancer cells in the bloodstream of the mice. The

technique works by shining a laser though the skin and into blood vessels, where

the dyed cancer cells are visible.

Results showed the increase in lipids had no impact on the original tumors

implanted in the mice. However, the rate of metastasis rose a dramatic 300

percent in the mice fed a high-fat diet.

The researchers later also examined the animals' lungs and counted the number of

cancer cells that had migrated to the lungs as a result of metastasis. Those

findings supported the other results showing increased metastasis in animals fed

a high-fat diet.

The researches used the imaging and cell-counting tools to document that

linoleic acid, which is predominant in polyunsaturated fats, caused increasing

membrane phase separation, whereas oleic acid, found in monounsaturated fats,

did not. Increased membrane phase separation could improve the opportunity of

circulating tumor cells to adhere to blood vessel walls and escape to organs far

from the original tumor site. The new findings support earlier evidence from

other research that consuming high amounts of polyunsaturated fat may increase

the risk of cancer spreading.

The findings suggest that combining CARS and intravital flow cytometry

represents a possible new diagnostic tool to screen patients for cancer. The

tool can be used to count lipid-rich tumor cells circulating in a patient's

blood by shining a laser through the skin and into blood vessels. Because lipids

can be detected without the need for dyes, the technique might be developed into

a convenient method to diagnose whether a patient's cancer is spreading

aggressively, Cheng said.

" These findings open the possibility of an entirely new, relatively simple

method for diagnosing whether cancer is metastasizing, " he said.

Future work will focus on not only how obesity increases metastasis but also how

it might play a direct role in initiating the development of cancers.

The research has been funded by the National Institutes of Health.

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Adapted from materials provided by Purdue University.

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Purdue University (2009, February 26). Excessive Dietary Fat Caused 300 Percent

Increase in Metastasizing Tumor Cells In Animal Models. ScienceDaily. Retrieved

April 26, 2009, from http://www.sciencedaily.com­

/releases/2009/02/090225172639.htm

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