Citrus flavonoid naringenin inhibits breast cancer metastasis
Daily supplementation with several hundred milligrams of naringenin - a substance in citrus fruits - may prevent breast cancer from spreading. That's what a Chinese animal study suggests.
Naringenin is a flavonoid, which resembles not only quercetin but also apigenin. Naringenin is found in citrus fruits, quercetin in onions and apigenin in parsley. As early as the 1990s, biochemists discovered that naringenin can protect laboratory animals against breast cancer. [Adv Exp Med Biol. 1998;439:227-36.] [Biol Pharm Bull. 2005 Mar;28(3):527-30.]
The researchers, affiliated with the Chinese Academy of Sciences, wondered whether naringenin in breast cancer can also inhibit the metastasis of tumors. They tried to answer that question with a series of experiments, which appeared in Protein & Cell in 2011.
Experiment 1 | Metastasis
The researchers injected aggressive breast cancer cells into two groups of mice and removed the tumors after 14 days.
Three days before surgery, the experimental group started taking daily naringenin supplementation. If the mice had been humans, they would have received 600-1000 milligrams of naringenin daily.
The mice in the control group were not given any supplements.
3 and 7 days after surgery, the researchers performed an autopsy on the mice and looked at metastasis of the tumors in the lungs. In the mice that had been given naringenin, the researchers found fewer metastases than in the control group. You can see this at the bottom left.
Experiment 2 | Survival
The researchers kept another part of the mice alive. The animals received naringenin three weeks after surgery, then no more. In the group of mice that had been given naringenin, 30 percent of the mice were still alive and tumor-free 160 days after injecting the cancer cells. In the other group, all mice had died. You can see that at the top right.
Experiment 3 | Mechanism
You can see, in part, below how naringenin inhibits the metastasis of cancer. You look at the concentration of the inflammatory factors interferon-gamma and interleukin-2 in CD8+ T cells of the mice. CD8+ T cells clear out cancer cells. The more interleukin-2 and interferon-gamma they make, the better they can do it.
"These results indicate that orally administered naringenin can inhibit the outgrowth of metastases after surgery via regulating host immunity", summarize the researchers. "Thus, naringenin can be an ideal surgical adjuvant therapy for breast cancer patients."
This post is about naringenin, but it could just be that similar flavonoid compounds have similar cancer-inhibiting effects. [Life Sci. 2020 May 1;248:117463.] [Cell Biosci. 2017 Oct 5;7:50.]
Protein Cell 2011, 2(6): 507-16.
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