Chillies turn up the heat on tumours

From NewScientist.com

Chillies turn up the heat on tumours

• 13:22 15 March 2006
• NewScientist.com news service
• Roxanne Khamsi

The same component of jalapeño peppers that makes them burn the tongue also appears to kill prostate cancer cells. Prostate tumours in mice treated with the compound, called capsaicin, shrank to one-fifth the size of those in non-treated mice, found a new study.

To explore capsaicin’s effect, Phillip Koeffler of the Cedars-Sinai Medical Center in Los Angeles, US, and colleagues exposed human prostate cancer cells in a laboratory dish to the natural compound. They found that capsaicin dramatically slowed the proliferation of the cells in the dish.

And this effect increased as the dose of the chilli compound was raised. Three per cent of prostate cancer cells committed “suicide” – programmed cell death – at low concentrations, rising to up to 75% of tumour cells dying at a higher dose.

Koeffler says this is the first experimental evidence supporting the notion that capsaicin stops the growth of prostate cancer cells.

Human cancer

He believes that capsaicin jump starts a pathway that triggers cell death. Molecular tests suggest that it achieves this by causing a cascade of events inside the cell that lead to the release of a protein complex called NF-kappa Beta, which subsequently causes the cell to self-destruct. This is crucial since cancer is characterised by the uncontrolled growth of cells.

The team also found that capsaicin suppressed the growth of human prostate cancer cells by about 80%. These cells were grafted into mice with suppressed immune systems.

But Koeffler says that men concerned about prostate cancer should not interpret these findings as a reason to up their consumption of hot peppers. He stresses that the compound has not been shown to prevent prostate cancer but instead simply slows its growth. And he adds that he hopes to see human trials in the next two years assessing capsaicin’s effect on prostate cancer.

Take a chilli pill

After prostate cancer is surgically removed, it tends to reappear in about a quarter of patients, the researchers note. For this reason, they say that capsaicin may be most effective in slowing cancer’s return instead of stopping it from first developing.

He adds that one also must take dosages into consideration. A 200-pound (90-kilogram) person would have to eat about 10 fresh habañera peppers – one of the hottest chillies around – per week to consume an amount of capsaicin equivalent to the levels received by Koeffler’s mice.

A habañera typically contains 300,000 Scoville units – a scale used to measure the hotness of chillis – making them positively scorching to the mouth in comparison with the more popular jalapeños, which contain roughly 2500 to 5000 Scoville units. For this reason, he says it is unreasonable to imagine anyone eating fresh peppers to prevent the return of prostate cancer: “You would have to take it in pill form.”

Journal reference: Cancer Research (DOI: 10.1158/0008-5472.CAN-05-0087)