CONTACT: JENNIFER CRONIN
2130 Medical Laboratories
Iowa City IA 52242
(319) 335-9917; fax (319) 335-8034
Release: Sept. 2, 1999
UI researchers discover aggressive cancer cells may
make own blood vessels
EDITOR'S NOTE: Background video, including interviews
with researchers, is available upon request. Please contact Tom Moore at (319)
IOWA CITY, Iowa Until now, researchers widely
assumed that tumors attracted nearby blood vessels to provide tumors with
nutrition and pathways for tumor cells to spread throughout the body. This
hypothesis, known as tumor angiogenesis, is the basis of intensive investigation
and clinical trials worldwide.
However, in a study published in the September issue
of the American Journal of Pathology, a University of Iowa research team reports
that highly aggressive cancer cells themselves may generate their own vascular
networks independent of angiogenesis. Because the researchers' discoveries
call attention to an alternative pathway that is responsible for aggressive
tumor growth and spread, the findings potentially could change the way cancers
are regarded, diagnosed and treated.
The UI investigation was conducted by Andrew J. Maniotis,
Ph.D., assistant research scientist in anatomy and cell biology; Robert Folberg,
M.D., UI professor of pathology and ophthalmology; and Mary J.C. Hendrix,
Ph.D., UI professor and head of anatomy and cell biology, and deputy director
of the UI Cancer Center; together with their colleagues.
The researchers discovered that as human cancer cells
progress toward more deadly forms, groups of aggressive cancer cells build
primitive vascular channels. The researchers found this to be true in both
specially engineered cultures and human cancer specimens.
The results may explain why aggressive cancers do
not respond to conventional chemotherapies or why tumor growth and spread
can continue even when conventional therapies are combined with experimental
chemotherapies that may block angiogenesis in animal models and in humans.
"The vascular channels form between tightly packed
groups of aggressive cells; and basic tissue processes, such as perfusion,
can continue to operate within the tumor even though more complexly orchestrated
processes are shut off by drugs or by the tumor itself as it grows," Maniotis
said. "In addition, because these vascular channels
can be constructed in the laboratory with human cells, new forms of cancer
therapy could be developed that would specifically interfere with the way
tumor cells pack together to form these channels."
Both before and after aggressive cancer cells spread,
the vascular channels form characteristic patterns in human cancer patients
that resemble those that are seen only in early embryos, Hendrix said.
Folberg added, "Because these patterns can be identified
through angiographs or by specialized ultrasound, it may be possible to develop
new non-invasive imaging tests to detect aggressive cancers. These tests may
complement and perhaps even substitute for some forms of invasive biopsies."
Although the UI researchers focused their attention
on ocular and skin melanoma, they have preliminary data suggesting that this
phenomenon may occur in other tumors. The researchers are awaiting scientific
peer review before they release any additional information.
Because this study deals with new and novel concepts
in cancer biology, the American Journal of Pathology article is accompanied
by a commentary by Mina Bissell, a noted breast cancer researcher and Life
Sciences Division director at the Lawrence Berkeley National Laboratory. The
journal Science also plans to include a story on the UI findings in its Sept.
In addition to Hendrix and Maniotis, the other researchers
from Hendrix's lab who were involved in this study included Angela Hess, UI
graduate student, and Elisabeth Seftor, research specialist. Folberg's research
assistant Lynn Gardner also contributed to this investigation, as did Jacob
Pe'er from the Hadassah University Hospital, and Jeffrey M. Trent and Paul
S. Meltzer from the National Institutes of Health (NIH), Human Genome Research
The research was made possible through support from
the UI Central Microscopy Research Facility and the Charles Hendrix Research
Foundation, and through grants from the National Eye Institute and the National
Cancer Institute, as well as a grant from Research to Prevent Blindness Inc.,
for which Folberg serves as a senior scientific investigator.
More information about the UI research is available
at the following Web sites: http://webeye.ophth.uiowa.edu/eyepath/