Recent studies from the lab of James Fox, MIT professor of biological engineering and director of DCM, showed that female mice with their ovaries removed so they could no longer produce estrogen lost their protection from gastric cancer. In another study, Fox gave estrogen to male mice soon after birth, and showed that it prevented the development of gastritis and precancerous gastric lesions.
In the new study, of which Fox is senior author, the researchers waited until the mice had already developed gastritis before giving them estrogen. The mice in the study were genetically engineered to produce large amounts of gastrin, a hormone that promotes acid production and proliferation of the cells that line the stomach. Such mice typically develop cancer within 20 months.
H. pylori infection speeds up that cancer progression, to about seven months. As in humans, males are much more likely than females to develop gastric cancer.
At age 24 weeks, 16 weeks after being infected with H. pylori, male mice in this study were treated with estrogen, Tamoxifen, both or neither. Female mice were treated with Tamoxifen or nothing. The researchers expected that Tamoxifen would undo the protective effects of estrogen, in both male and female mice.
However, among the male mice, all three treated groups estrogen, Tamoxifen or both were protected from gastric cancer. In fact, none of those mice developed cancer, even though they all had gastritis before receiving treatment. Forty percent of the untreated mice developed gastric cancer.
Among the female mice, those who received Tamoxifen showed no differences from the untreated mice. That surprising finding suggests that in the stomach, Tamoxifen may mimic estrogen's effects, rather than blocking them.
To figure out how estrogen and Tamoxifen protect
|Contact: Marta Buczek|
Massachusetts Institute of Technology