Dad's Genes May Be to
Blame in Cancer, Study Finds
Excerpt by Maggie Fox, HealthDay

A father's genes, already known to urge a developing embryo to grow faster and bigger, may be to blame in some cancers, researchers reported.

They found three different genes can help tumor cells grow if a basic early genetic process called imprinting goes awry.

The findings, published in the Proceedings of the National Academy of Sciences, could help explain at least some cases of the out-of-control cell growth that marks cancer.

"It shows clearly that the father's genome seems to have an intrinsic ability to accelerate growth, whereas the mother's genome has the ability to retard growth," said Dr. Colin Stewart, an embryology expert at the U.S. National Cancer Institute.

"The two balance one another to give a normal growth pattern," Stewart, who led the study, said in a telephone interview. "But if the process is abnormal, it may contribute to the formation of some cancers."

Stewart's team investigated the genetics underlying imprinting. Usually, a baby inherits half its genes from the mother and half from the father.

The imprinting process ensures that, depending on the gene, either the mother's or the father's copy is the only one active. Imprinting is especially important in the development of a fetus, controlling how large it grows.

Doctors know a baby's size is the result of a tug-of-war between the parents' genes, with the father's contribution trying to make the baby grow as large as possible and the mother's acting as a brake.

Stewart said his team's findings show how this process works and how it may cause cancer when things go wrong.

"It may be involved in cancer in general. We don't know at present," he said. "Any imbalance of these particular genes may be important contributing factors to the development of cancer."

His team grew cells from mice that either had only the mother's genes active or the father's.

"We looked at the growth properties of these cells. What we found to our surprise was that cells with exclusively the father's genome grow faster. They show a very great propensity to suddenly grow malignant and form rapidly growing tumors ... whereas the cells with the maternal genome grow more slowly and eventually die."

Many different genes are known to be involved in cancer, but some genes underlie different functions in the body while others are more specific. The genes identified by Stewart may be involved in a general tendency, he said.

The three genes are known as p57kip2 and M6P/IGF2r from the mother and Igf2 from the father.

The finding may also have significance for cloning and stem cell research, Stewart said.

Scientists are looking into the possibility of making stem cells from parthenotes -- egg cells that are induced to start growing as if they were a fertilized egg-turned-embryo.

Stem cells are the body's master cells and are considered a potential source of tissue transplants to cure a wide range of diseases. But they are difficult to come by.

Stewart said his findings suggest that using a woman's eggs as a source of these cells would not work. "They may grow for a few days but eventually they will peter out," he said.

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