Fasting may shield healthy cells from toxic effects of chemotherapy

CANCER
Chemotherapy is effective at killing cancer cells, but it can also be pretty toxic to healthy cells, leading to hair loss, diarrhea, and immune problems. Now, a new study suggests a surprising intervention that might make healthy cells more resistant to the toxic effects of chemotherapy: starvation. Researchers have known for some time that starving cells makes them hardier to toxins - for example, when mice are fed low-calorie diets, they tend to avoid cell death and live longer. Why this happens isn't completely clear, but its possible that when normal, healthy cells are deprived of nutrition, they hunker down in a "stress response" that gives them special resistance. Based on this idea, researchers, including principal investigator Valter Longo of the University of Southern California, put mice with cancer on starvation diets for 48 hours and then gave them high doses of chemotherapy. They found that healthy cells were protected, while the abnormal tumor cells, which were unable to trigger the "stress response," were susceptible to the chemotherapy. How nutrition might tie into chemotherapy treatments in humans needs more work, but Longo believes clinical trials based on this principle might lead to new and more effective ways to treat cancer.

BOTTOM LINE: Preliminary evidence suggests that starving healthy cells might shield them from the toxic effects of chemotherapy, allowing more targeted destruction of abnormal cancer cells. CAUTIONS: "These studies are limited to cell lines and mice," says Longo.

WHAT'S NEXT: Large clinical trials are needed to evaluate the role of diet and nutrition in cancer treatment for humans.

WHERE TO FIND IT: Proceedings of the National Academy of Sciences, March 31.

SUSHRUT JANGI

BIOLOGY

Fetal cells can remain in a woman's bloodstream for years after a donor egg pregnancy, somehow evading rejection by the mother's immune system, a new study suggests. Scientists have known for some time that fetal cells persist in the bodies of women who've been pregnant, including women whose pregnancies ended in miscarriage or abortion. However, just how this process, called microchimerism, happens - and why - remain unknown. One question was whether fetal cells remain in the mother only when the embryo was created with the mother's egg. To find out, researchers at Brigham and Women's Hospital in Boston looked for the presence of male cells in the blood of 11 healthy women age 18 to 60 whose donor-egg pregnancy resulted in male offspring. To determine whether the male cells were present only as a result of the donor-egg pregnancy, the scientists excluded women who'd had a baby with their own eggs or other potentially confounding factors. Analysis revealed male cells in all 11 women, including one woman nine years after her pregnancy. Understanding how these cells avoid rejection by the mothers' immune systems could have implications for transplant medicine, says Dr. Zev Williams, lead author and the Brigham's chief resident in obstetrics and gynecology. "Somehow these cells have a way of hiding from the immune system without suppressing the mother's immune system, and we want to know how and why they do that."

BOTTOM LINE: Fetal cells persist in women for years after a donor-egg pregnancy, suggesting a unique mechanism for evading rejection by the mother's immune system.

CAUTIONS: While the findings raise interesting questions, "clinical applications are many years away," Williams says.

WHAT'S NEXT: Researchers want to know how the cells hide from a mother's immune system and what role - if any - the cells play in the mother's body. "The biological significance is unclear," said Dr. Diane Bianchi, a scientist at Tufts University School of Medicine and one of the first to discover fetal cells in mothers' blood years after pregnancy.

WHERE TO FIND IT: Fertility and Sterility, online April 1.

KELLI WHITLOCK BURTON