Obesity is a known risk factor for certain types of cancer, including colon cancer, pancreatic cancer and breast. Studies have shown its role in promoting tumor growth and cancer progression, but in the initiation of cancer has been uncertain.
"Epithelial" the cells lining the surface of the organs have intrinsic ability to remove potentially malignant cells from their environment. This mechanism is called "epithelial cancer protection." Cells were perceived harmful cells and replacing them by a process called cell competition.
To study how obesity affects the protective mechanism, the researchers from Hokkaido University and employees bred mice that have been designed to express a well-known cancer-inducing mutant protein called Ras. Epithelial cells are typically removed potentially malignant Ras-transformed cells.
Feeding mice with racial high fat diet, leading to severe obesity, it inhibited the protective mechanism and hence increased the number of Ras-transformed cells remaining in the tissue. This inhibition was observed in the gut and pancreas, but not lung. Besides, in a month Ras-transformed cells have developed a tumor of the pancreas of mice with a high fat content. The result supports the previous correlation between intestinal cancer and pancreatic cancer and obesity, but not lung cancer.
Following experiments using mouse models and cultured cells revealed that fatty acids and cause chronic inflammation suppression protective mechanism.
When the mice fed a diet with a high fat diet, treated with aspirin, known for its anti-inflammatory properties, the mechanism of protection was significantly enhanced. This means that the amplification mechanism for protecting epithelial anti-inflammatory drugs may be used to prevent cancer.
"This is the first report that shows that obesity and chronic inflammation may affect the competitive interactions between normal cells and transformed cells. This implies that other factors, such as infection, smoking, sleep and aging, can affect cell competition ", - says Yasuyuki Fujita from Hokkaido University, who led the study.