LONDON (Reuters) - A molecule found in a curry ingredient can kill esophageal cancer cells in the laboratory, suggesting it might be developed as an anti-cancer treatment, scientists said on Wednesday.

Researchers at the Cork Cancer Research Center in Ireland treated esophageal cancer cells with curcumin -- a chemical found in the spice turmeric, which gives curries a distinctive yellow color -- and found it started to kill cancer cells within 24 hours.

The cells also began to digest themselves, they said in a study published in the British Journal of Cancer.

Previous scientific studies have suggested curcumin can suppress tumors and that people who eat lots of curry may be less prone to the disease, although curcumin loses its anti-cancer attributes quickly when ingested.

But Sharon McKenna, lead author of the Irish study, said her study suggested a potential for scientists to develop curcumin as an anti-cancer drug to treat esophageal cancer.

Cancers of the esophagus kill more than 500,000 people across the world each year. The tumors are especially deadly, with five-year survival rates of just 12 to 31 percent.

McKenna said the study showed curcumin caused the cancer cells to die `using an unexpected system of cell messages.`

Normally, faulty cells die by committing programed suicide, or apoptosis, which occurs when proteins called caspases are `switched on` in cells, the researchers said.

But these cells showed no evidence of suicide, and the addition of a molecule that inhibits caspases and stops this `switch being flicked` made no difference to the number of cells that died, suggesting curcumin attacked the cancer cells using an alternative cell signaling system.

U.S. researchers said in 2007 they had found curcumin may help stimulate immune system cells in the Alzheimer`s disease.

(Reporting by Kate Kelland Editing by Janet Lawrence)