Micrograph showing a lymph node invaded by ductal breast carcinoma, with extension of the tumour beyond the lymph node. Credit: Nephron/Wikipedia
The high amounts of dietary sugar in the typical Western diet may increase the risk of breast cancer and metastasis to the lungs, according to a study at The University of Texas MD Anderson Cancer Center. The findings, demonstrated dietary sugar’s effect on an enzymatic signaling pathway known as 12-LOX (12-lipoxygenase).
“We found that sucrose intake in mice comparable to levels of Western diets led to increased tumor growth and metastasis, when compared to a non-sugar starch diet,” said Assistant Prof. Peiying Yang, Ph.D. “This was due, in part, to increased expression of 12-LOX and a related fatty acid called 12-HETE.”
Previous epidemiological studies have shown that dietary sugar intake has an impact on breast cancer development, with inflammation thought to play a role.
“The current study investigated the impact of dietary sugar on mammary gland tumor development in multiple mouse models, along with mechanisms that may be involved,” said Prof. Lorenzo Cohen, Ph.D. “We determined that it was specifically fructose, in table sugar and high-fructose corn syrup, ubiquitous within our food system, which was responsible for facilitating lung metastasis and 12-HETE production in breast tumors.” Moderate sugar consumption is critical, given that the per capita consumption of sugar in the U.S. has surged to over 100 lbs/y and an increase in consumption of sugar-sweetened beverages has been identified as a significant contributor to an epidemic of obesity, heart disease and cancer worldwide.
The MD Anderson team conducted 4 different studies in which mice were randomized to different diet groups. At 6 months of age, 30% of mice on a starch-control diet had measurable tumors, whereas 50 – 58% of the mice on sucrose-enriched diets had developed mammary tumors. The study also showed that numbers of lung metastases were significantly higher in mice on a sucrose- or a fructose-enriched diet vs mice on a starch-control diet.
“This study suggests that dietary sucrose or fructose induced 12-LOX and 12-HETE production in breast tumor cells in vivo,” said Cohen. “This indicates a possible signaling pathway responsible for sugar-promoted tumor growth in mice. How dietary sucrose and fructose induces 12-HETE and whether it has a direct or indirect effect remains in question.”
http://www.mdanderson.org/newsroom/news-releases/2015/sugar-diets-increases-risk-breast-cancer-tumors-metastasis.html
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