Different type of colon cancer vaccine reduces disease spread, Jefferson scien...( (PHILADELPHIA) Taking advantage of ...),Health

(PHILADELPHIA) Taking advantage of the fact that the intestines have a separate immune system from the rest of the body, scientists at the Kimmel Cancer Center at Jefferson in Philadelphia have found a way to immunize mice against the development of metastatic disease.

Reporting online Tuesday, June 24, 2008 in the Journal of the National Cancer Institute, Scott Waldman, M.D., Ph.D., professor and chair of Pharmacology and Experimental Therapeutics at Jefferson Medical College of Thomas Jefferson University and his co-workers have shown that mice immunized with an intestinal protein developed fewer lung and liver metastases after injection with colon cancer cells than did control animals that were not immunized. The work may portend the development of a different kind of cancer vaccine, the researchers say, that may help prevent disease recurrence.

One of the reasons that cancer vaccines have been disappointing in many cases is the lack of immune system-alerting protein antigens that are specific for tumors only. According to Dr. Waldman, mucosal cells, which line the intestines (colon cancer arises from mucosal cells, and mucosal cell proteins continue to be expressed even after they become cancer) are essentially compartmentalized and possess a separate and distinct immune system from the body's general immune system. He and his group thought that such proteins would be seen as foreign by the latter system and be useful for anti-cancer vaccines.

Dr. Waldman, postdoctoral fellow Adam Snook, Ph.D., and their colleagues engineered viruses adenovirus, vaccinia and rabies to express the protein guanylyl cyclase C (GCC), which is normally found in the intestinal lining (and in metastatic colon cancer). The researchers injected the animals with colon cancer cells before or after immunization.

They found that the vaccinated animals developed fewer metastases in the liver and lung 90 percent and 75 percent, respectiv
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