songw, Here's more good news for retinoids. The damage that smokers do to their lungs seems to be long lasting, even after they stop smoking. However, researchers are now looking at the use of retinoids to reverse these changes which appear to be precursors for the development of lung cancer. Thus, in addition to preventing breast cancer and type II diabetes, retinoids may also have applications for preventing lung cancer:
Molecular Changes Persist In Lung Epithelium Of Former Smokers
WESTPORT, Sep 17 (Reuters) - Although the bronchial tissues are known to recover
after an individual quits smoking, new evidence published in the September 17 issue of
the Journal of the National Cancer Institute shows that DNA changes linked to the
early stages of carcinogenesis persist in former smokers.
A multinational team, led by Dr. Adi F.Gazdar of the University of Texas Southwestern
Medical Center in Dallas, collected multiple lung epithelium biopsy specimens from 18
smokers, 24 former smokers and 21 never-smokers. They looked for loss of
heterozygosity at 8 loci, as well as 15 polymorphic microsatellite DNA markers linked
to lung cancer in the lung tissues.
While 97% of biopsy specimens obtained from nonsmokers were histologically normal,
the majority of "...biopsy specimens from both current and former smokers
demonstrated the entire spectrum of preneoplastic pathologic changes associated with
lung cancer." Specifically, 96% of biopsies from current smokers and 75% of those
from former smokers were histologically abnormal.
In addition, Dr. Gazdar and others observed loss of heterozygosity at one or,
frequently, multiple regions in almost half of biopsy specimens from current and former
smokers, including half of those specimens that were histologically normal. The
majority of smokers, 86%, "...had allelic loss in at least one biopsy specimen,
and...24%...demonstrated allelic loss in every biopsy specimen analyzed." Moreover,
the investigators identified microsatellite alterations in 64% of smokers.
In sharp contrast, no molecular changes were identified in any of the 67 biopsy
samples obtained from never-smokers, even those with a history of occupational
exposure to asbestos.
In addition, the finding that loss of heterozygosity at regions 3p and 9p was more
common in smokers than similar changes on chromosomes 5q, 17p and 13q suggests
that loss of heterozygosity at 3p and 9p may represent one of the earliest molecular
targets in lung cancer carcinogenesis, according to the authors.
Dr. Gazdar comments in a UT Southwestern press release that he and colleagues
"...are currently exploring whether these changes can be reversed by various
chemoprevention agents such as retinoids. These changes may also be useful for risk
assessment, so as to determine which smokers are at highest risk for developing lung
cancer."
J Natl Cancer Inst 1997;89:1366-1373.
-Westport Newsroom 203 319 2700 |
