Mechanism Explains How Pregnancy Inhibits Cancer
Study suggests α-fetoprotein is the proximal agent that reduces lifetime risk of breast cancer
MONDAY, Nov. 30 (HealthDay News) -- During pregnancy, production of the cancer-inhibiting agent α-fetoprotein (AFP) from the liver may explain why parity is associated with reduced lifetime risk of breast cancer, according to a study published online Nov. 24 in Cancer Prevention Research.
Herbert I. Jacobson, Ph.D., of Albany Medical College in New York, and colleagues exposed female rats to cancer-inducing nitrosomethylurea, and then treated them with saline, Estrogen3, Estrogen2 plus progesterone, Estrogen3 plus progesterone, or allowed them to become pregnant.
The researchers found that all of the hormone treatments were associated with increased serum AFP levels and a lower incidence of breast cancer in the rats. They also used the same hormonal agents to treat human HepG2 liver cells in culture. They found that all of the treatments increased levels of AFP and inhibited the Estrogen2-induced proliferation of MCF7 breast cancer cells. However, when the medium was stripped of AFP, they found that it not only failed to inhibit the growth of cancer cells but led to an overgrowth of cancer cells.
"Taking all of these data together, it is logical to conclude that AFP is a key mediator through which the pregnancy-induced, or hormone-induced, reduction in breast cancer is realized," the authors write. "Capturing this oncostatic property in analogues of AFP could lead to a rational process for the treatment and prevention of breast cancer."