Why Obesity Can Lead To Cancer

Inflammation associated with obesity impairs the body’s defense against cancer, suggesting that anti-inflammatory drugs such as aspirin could help prevent cancer.

AsianScientist (May 4, 2018) – A research group in Japan has discovered that obesity inhibits a critical cellular defense mechanism against cancer. They published their findings in Cell Reports.

Obesity is a known risk factor for certain types of cancer, including colon, pancreatic and breast cancer. Studies have shown that obesity promotes tumor growth and malignant progression, though the reasons underlying this observation remain unclear.

Epithelial cells lining the surfaces of organs have the intrinsic ability to remove potentially malignant cells from their midst. This is called the epithelial defense against cancer (EDAC) mechanism, wherein normal cells sense harmful cells and push them out by a process called cell competition.

To study how obesity affects this defense mechanism, researchers from Hokkaido University and their collaborators bred mice that were designed to express a known cancer-inducing mutant protein, called Ras. Epithelial cells usually remove the potentially malignant Ras-transformed cells.

However, when the Ras mutant mice were fed high-fat diets, causing them to become severely obese, the EDAC mechanism was suppressed. This resulted in an increased number of Ras-transformed cells in the mice.

The researchers noted that obesity-induced suppression of the EDAC mechanism occurred in the intestine and pancreas, but not in the lungs. Their findings support previous studies correlating intestinal and pancreatic cancer with obesity, but not lung cancer.

Subsequent experiments in mice and cultured cells revealed that fatty acids and chronic inflammation were responsible for suppressing the EDAC mechanism. When mice on a high-fat diet were treated with aspirin, known for its anti-inflammatory properties, the defense mechanism was substantially enhanced. This implies that reinforcing the EDAC mechanism with anti-inflammatory drugs could prevent cancer.

“This is the first report to show that obesity and chronic inflammation can influence the competitive interaction between normal cells and transformed cells. It implies that other factors such as infection, smoking, sleeping patterns and aging may also affect cell competition,” said study leader Dr. Yasuyuki Fujita of Hokkaido University, Japan.

The article can be found at: Sasaki et al. (2018) Obesity Suppresses Cell-Competition-Mediated Apical Elimination of RasV12-Transformed Cells from Epithelial Tissues.


Source: Hokkaido University; Photo: Shutterstock.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

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