Researchers at UC Davis, University of Massachusetts and Harvard Medical School have
created a combination drug that controls both tumor growth and metastasis. By combining a COX-2 inhibitor, similar to Celebrex, and an epoxide hydrolase (sEH) inhibitor, the drug controls angiogenesis (blood vessel formation), limiting a tumor's ability to grow and spread. The study appears today in the journal Proceedings of the National Academy of Sciences.
"We've been studying the effects of COX and sEH inhibitors, both by themselves and in combination, for several years," said senior author and UC Davis Distinguished Professor Bruce Hammock. "We were surprised to find that the dual inhibitor was more active than higher doses of each compound, either individually or together. By combining the two molecules into one we got much greater potency against several diseases and completely unique effects in terms of blocking tumor growth and metastasis."
Both COX and sEH enzymes control lipid signaling, which has long been associated with inflammation, cell migration, proliferation, hypertension and other processes. COX inhibitors block production of inflammatory and pain-inducing lipids, while sEH inhibitors preserve anti-hypertensive, anti-inflammatory and analgesic compounds. Separate COX and sEH inhibitors were previously found to work together in reducing inflammation and neuropathic pain.
After testing individual COX-2 and sEH inhibitors, the team synthesized the drug (PTUTB), the first combined COX-2/sEH inhibitor. They then tested the dual inhibitor against human lung and breast tumors, both in vitro and in mice. They found that PTUTB blocked angiogenesis, inhibiting the proliferation of endothelial cells, which are critical to blood vessel formation. This in turn limited tumor growth and metastasis, reducing lung and breast tumor growth by 70 to 83 percent.
In breast and lung cancers, the dual inhibitor blocked angiogenesis, which blocked the growth of solid tumors," said Hammock. "This represents a new mechanism to control blood vessel and tumor growth."
Robert Weiss, a co-author and professor of nephrology at UC Davis, added that the combination drug achieved the results with minimal side effects and no cardiovascular or gastrointestinal effects.
"This is particularly important when administering COX-2 inhibitors, which have well-known cardiovascular risks," he said. "However, the added sEH inhibitor appears to block COX-2's side effects."
The research was initiated by first author Guodong Zhang when he was a postdoctoral fellow in the Hammock laboratory. Zhang previously demonstrated that sEH inhibitors improve the power of omega-3 fatty acid (fish oil) diets to reduce tumor growth and metastasis, and implicated epoxides of the dietary supplement DHA as the causative agent.
