Dummy Cell Receptor Reduces Tumor Size and Spread

An animal study had found that a specially designed cell receptor may reduce cancer death rates by soaking up excess tumor-produced chemicals like a sponge. The study, led by researchers at the University of California, Irvine (UCI, USA), was reported in the January 2002 issue of Molecular Cancer Therapeutics.

Using human pancreatic cancer cells in mice, the researchers found that the binding of growth factors to dummy receptors--those incapable of sending signals to cells-- had the effect of sharply reducing tumor size and decreasing the spread of cancer cells to other parts of the body. The dummy receptors acted like a sponge, mopping up excess levels of the growth factor TGF-beta, found in cancer cells. Mice with the dummy receptor for TGF-beta showed a 72% reduction in tumor growth one week after injection compared to mice without the receptor. After 50 days, mice with the receptor had an average tumor cell volume of less than 50 cubic mm, while mice without the dummy receptor had tumor cell volume of about 300 cubic mm.

Also, when parts of the tumor cells were injected into mice known to show metastatic spreading, those mice with the dummy receptor showed far less evidence of metastasis than mice without the receptor. In a similar method, dummy receptors for tumor necrosis factor (TNF) are being used clinically to reduce excessive inflammation in arthritis patients.

"This study confirms our earlier findings suggesting that increased levels of TGF-beta make pancreatic cancer cells grow more aggressively,” said Dr. Murray Core, professor of medicine and chief of endocrinology at UCI Medical Center. "We were originally surprised to see these high levels of TGF-beta expressed in pancreatic cancer, since it generally inhibits cell growth. This new role for TGF-beta may lead us to design targeted therapies against pancreatic and other cancers marked by high levels of this growth factor.”