help --on free radicals and promotion

Chuck Miller rellim at MAILHOST.TCS.TULANE.EDU
Mon Nov 2 12:10:22 EST 1998

allayl at uqu.edu.sa wrote,

"Can anyone help me in understanding the role of free radicals
in promoting cells cancer?"

Agents that induce free radicals are capable of damaging DNA (initiation).
Many initiating agents which are complete carcinogens produce free radicals
(ionizing and UV radiation for examples). Production of free radicals may
be part of why a complete carcinogen is "complete". A number of agents
known more for their promotion effects (phorbol esters, steroids,
peroxisome proliferators) elicit free radicals. These agents may elaborate
free radicals, which facilitate the outgrowth of initiated cells. In some
cases free radicals may be involved in the normal mitogenic process. In
other cases free radicals can lead to cell death or reduce the capacity of
cells to divide. Following radical damage, the limited (perhaps initiated)
pool of cells that remains competent to divide can be forced to undergo
repeated rounds of cell division in an effort to replace dead or damaged
cells. These cells expand and may ultimately result in a cancer.

Dr. Charles A. Miller III,   rellim at mailhost.tcs.tulane.edu
Dept. Environmental Health Sciences, SL29
Tulane-Xavier Center for Bioenvironmental Research and
Tulane Univ. School of Public Health and Tropical Medicine
1430 Tulane Ave.
New Orleans, LA 70112
(504)585-6942, fax (504)584-1726
Bionet.toxicology newsgroup: http://www.bio.net/hypermail/TOXICOLOGY

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