In addition, the reason for a polyp link to growth hormone has been unclear. But new research from the University of North Carolina at Chapel Hill indicates the probable answer: loss of function of one of a pair of genes that normally would inhibit growth hormone signals inside the cell.

The study also offers a possible molecular marker that could help determine which people taking growth hormone therapy are at increased risk for colon polyps. Researchers already know that colon polyps tend to occur in people who already have excessive amounts of growth hormone, such as those with a disease called acromegaly, or gigantism.

A report of the study appears in the April issue of the medical journal Endocrinology.

Study senior author Dr. P. Kay Lund, professor of cell and molecular physiology within UNC's School of Medicine and a member of the UNC Lineberger Comprehensive Cancer Center, said she and her team had been interested in looking at the effect of a newly discovered inhibitor of cellular growth hormone signaling, suppressor of cytokine signaling-2, or SOCS2.

This molecule limits growth hormone action on the body and organ growth, but its role in growth hormone action on intestine is unknown, Lund said.

"Much of the work on SOCS2 had been done in cell cultures. We wanted to study it in vivo, in laboratory animals, with a focus on how it stops the action of cellular growth hormone."

The researchers thought an ideal way to study this issue would be to use an animal model of acromegaly, laboratory mice having excessive amounts of growth hormone.

The animals were crossed with animals in which the SOCS2 gene was deleted. The breeding generated animals with excessive growth hormone and one or two functional SO
'"/>

Contact: Leslie H. Lang
llang@med.unc.edu
919-843-9687
University of North Carolina School of Medicine
7-Apr-2006