This sugar killing honeybees may help fight cancer

NEW YORK: A sugar that is crucial to many physiological processes in humans, but lethal to honeybees, can help inhibit the growth of cancer cells, according to a study. 

The findings, published in the journal eLife, suggest that mannose, a natural sugar that occurs in microbes, plants and animals, could be a helpful secondary treatment for cancer. 

Mannose is a sugar that the body adds to proteins to stabilise their structure and help them interact with other molecules. 

This process, called glycosylation, is essential for life; and malfunctions in glycosylation are associated with rare, but often life-threatening, human diseases. 

Free mannose is also found in small amounts in many fruits such as oranges, apples and peaches and in mammalian plasma at 50-100 micrometre.

"This sugar could give cancer an extra punch alongside other treatments. And because mannose is found throughout the body naturally, it could improve cancer treatment without any undesirable side effects," said Hudson Freeze, director of the Human Genetics Programme at Sanford Burnham Prebys in the US. 

"Until now, the most promising therapeutic use for mannose was to treat congenital disorders of glycosylation, diseases that can cause a wide range of severe symptoms throughout the body. But we believe that there may be ways to leverage mannose against cancer and other diseases as well," Freeze said. 

Mannose has already been shown to inhibit the growth of several types of cancer in the lab, but scientists do not fully understand why this happens. 

To learn more, the research team turned their attention to an unusual property of mannose observed in an unlikely subject -- honey bees. 

"It's been known for more than a century that mannose is lethal to honeybees because they can't process it like humans do -- it's known as 'honeybee syndrome'," Freeze said. 

"We wanted to see if there is any relationship between honeybee syndrome and the anti-cancer properties of mannose, which could lead to an entirely new approach to combat cancer." 

Using genetically engineered human cancer cells from fibrosarcoma -- a rare cancer that affects connective tissue -- the research team re-created honeybee syndrome and discovered that without the enzyme needed to metabolise mannose, cells replicate slowly and are significantly more vulnerable to chemotherapy. 

"We found that triggering honey bee syndrome in these cancer cells made them unable to synthesise the building blocks of DNA and replicate normally," Freeze said. 

"This helps explain the anti-cancer effects of mannose that we've observed in the lab." 

While leveraging honeybee syndrome could be a promising supplemental cancer treatment, the researchers caution that because the effect is dependent on vital metabolic processes, more research is needed to determine which types of cancer would be most vulnerable to mannose.