In fact, the more advanced the colorectal cancer cells are, the more grape seed extract stops their growth and survival, the authors added.
Not only does grape seed extract target the cancer cells effectively, it also leaves healthy cells alone.
Molly Derry, a doctoral candidate in the lab of Rajesh Agarwal, PhD, investigator at the CU Cancer Center and professor at the Skaggs School of Pharmacy and Pharmaceutical Sciences, said:
"We've known for quite a while that the bioactive compounds in grape seed extract selectively target many types of cancer cells. This study shows that many of the same mutations that allow colorectal cancer cells to metastasize and survive traditional therapies make them especially sensitive to treatment with GSE."
The researchers say that their finding is especially important today, because of increasing colorectal cancer rates, partly as a result of sedentary lifestyles and high-fat diets.
Few people get screened for colorectal cancer, which means that over 60% of those who are diagnosed already have advanced disease.
The seeds of grapes are used to make grape seed extract
Derry says "Finding a way to selectively target advanced colorectal cancer cells could have major clinical importance."
The team carried out a study on colorectal cancer cell lines which represented several stages of the disease. While much larger chemotherapy doses are required to kill a stage IV cancer than a stage II, they noticed that as far as grape seed extract was concerned, the opposite was true.
Derry explained "It required less than half the concentration of GSE to suppress cell growth and kill 50 percent of stage IV cells than it did to achieve similar results in the stage II cells."
The scientists say they discovered grape seed extract's likely mechanism for the preferential targeting for advanced colorectal cancer cells. When antioxidants are used to treat the cancer cells, the grape seed extract (GSE) induced cell death was reversed. The team believe it is likely that grape seed extract targets colorectal cancer by introducing oxidative stress, with results in apoptosis (cell death).
"A colorectal cancer cell can have upwards of 11,000 genetic mutations - differences from the DNA in healthy cells. Traditional chemotherapies may only target a specific mutation and as cancer progresses more mutations occur. These changes can result in cancer that is resistance to chemotherapy. In contrast, the many bioactive compounds of GSE are able to target multiple mutations. The more mutations a cancer presents, the more effective GSE is in targeting them."
Several studies over the last few years have shown that grape seeds have anti-cancer qualities: