How Fat Impacts Cancer Spread

Photo: 2 shining dots (cancer cells) before dark background

Two lipid-rich cancer cells attach to
collagen, the usual step before
spreading to organs; © Purdue

The researchers implanted a cancerous lung tumour 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 enhance cancer metastasis.

"If the cancer cells do not have excess lipids they stick together and form very tight junctions in tumours, but increasing lipids causes them to take on a rounded shape and separate from each other," Thuc T. Le, a National Institutes of Health postdoctoral fellow at Purdue, 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 tumours 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 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 tumour 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, Le said.; Source: Purdue University