The study – published in BMC Gastroenterology – finds that the compound, which is one of the most common flavones found in fruit and vegetable products, is able to inhibit the activity of cell signalling pathways important for the growth of cancer in colon cancer cells.
“Our study, showing that luteolin interferes with cell signalling in colon cancer cells, is a step forward in understanding how this flavonoid works,” explained Professor Jung Han Yoon Park of Hallym University, Korea – who led the study.
Nutrition and cancer
Colon cancer is the second most frequent cause of cancer-related death in the Western World.
The research team explained that colon cancer cells have elevated levels of a protein known as insulin-like growth factor II (IGF-II) compared to normal tissue.
It is thought that this is part of the mechanism that drives uncontrolled cell division and cancer growth, said the authors. Insulin-like growth factors (IGFs) are proteins that stimulate the growth of a variety of mammalian cells – the effects of which are mediated through the insulin-like growth factor receptor (IGF-IR).
The researchers noted that many in vitro lab studies have suggested that luteolin has anti-inflammatory, anti-oxidant and anti-cancer properties but results from epidemiological studies have been less certain.
Preliminary research has also suggested that luteolin could act as a free radical scavenger, a promoter of carbohydrate metabolism, or an immune system modulator.
The flavonoid is (full name 3’,4’,5,7-tetrahydroxyflavone) is found in a variety of vegetables, fruits, and medicinal herbs, and has also been shown to induce cell cycle arrest and cell death (apoptosis) in liver and lung cancer, and leukemia, cell lines.
Using cell cultures, the Korean researchers showed that luteolin was able to block the secretion of IGF-II by colon cancer cells, and found that within two hours had decreased the amount of receptor (IGF-IR) precursor protein.
Luteolin was also seen to reduce the amount of active receptors, and inhibited the growth stimulatory effect of IGF.
The team said that luteolin affected cell signalling pathways which are activated by IGF-I in cancer.
“Luteolin reduced IGF-I-dependent activation of the cell signalling pathways PI3K, Akt, and ERK1/2 and CDC25c. Blocking these pathways stops cancer cells from dividing and leads to cell death,” said Jung Park.
Source: BMC Gastroenterology
Published online ahead of print, Volume 12, doi: 10.1186/1471-230X-12-9
“Luteolin decreases IGF-II production and downregulates insulin-like growth factor-I receptor signaling in HT-29 human colon cancer cells”
Authors: D.Y. Lim, H.J. Cho, J. Kim, C.W. Nho, K.W. Lee, J.H.Y. Park