NEW YORK, Jun 01 (Reuters Health) - It may soon be possible to foil the
growth of tumors by blocking an enzyme linked to tumor blood vessel growth. A
team of multicenter researchers has taken drugs that block cyclooxygenase-2
(COX-2) and demonstrated that production of a blood vessel growth factor called
VEGF was reduced by 92%. The treatment could literally starve tumors of blood,
slowing their growth.
"Tumor growth requires the maintenance and expansion of a vascular network,"
write Dr. Raymond DuBois of Vanderbilt University Medical Center in Nashville,
Tennessee and colleagues at the University of Kansas Medical Center, Kansas City
and Osaka University School of Medicine in Japan. The investigators believe that
COX-2 inhibition stunts a tumor's ability to grow by reducing its capacity to
create blood vessels. This process, called angiogenesis, is mediated by VEGF.
According to the report published in the June 1st issue of the Journal of
Clinical Investigation, mice who lack an active gene for COX-2 had lung tumors
that "were significantly smaller" than control mice--those with the active gene.
Moreover, these smaller tumors "continued to grow more slowly than control
tumors for the remainder of the experiment," the study authors write. The
researchers do point out, however, that "the absence of COX-2...did not
permanently halt (cancer) growth."
In the next part of their experimental work, Dubois and his team gave the
mice a drug called celecoxib, commonly used to treat arthritis. Their goal was
to determine whether the drug, a known inhibitor of COX-2, would hamper tumor
growth. While "celecoxib treatment (did inhibit) tumor growth...the results were
not as striking as those obtained in (COX-2- deficient animals)."
The authors suggest that the "variation may be due to differences between
total lack of COX-2 versus intermittently inhibiting COX-2 activity by treatment
with dietary celecoxib."
The celecoxib results suggest that derivatives of the anti-inflammatory
drugs such as aspirin or ibuprofen may one day prove useful in the control of
certain kinds of tumors.
