A new approach to the study of breast cancer that examined cancercells in their "natural environment" could lead to a fundamentalrethinking of the biology of cancer cells and revolutionize howresearchers look at a whole panorama of genes, according to PatriciaSteeg, a scientist with the National Cancer Institute in Washington,D.C.The study was presented at the annual meeting of the AmericanAssociation for Cancer Research (AACR) that concluded yesterday inSan Francisco.Steeg's comments referred to a process devised by Mina Bissell ofLawrence Berkeley Laboratory in Berkeley, Calif, to distinguishnormal from malignant human breast cells in cultures. She establisheda simple but informative three-dimensional assay that provided arealistic environment for the study of the cells."Primary human cells are very difficult to grow and the distinctionsbetween normal and tumor cells are blurred in two-dimensionalconventional cultures," Bissell reported. "We are now in a position todefine meaningful markers for normal and malignant cells and toanalyze the basis for such dramatic differences in behavior in our assaysystem."Bissell found that studying the functional significance of "suppressorgenes" in this way brought surprising results. She noted that metastaticcells that overexpress a transfected tumor suppressor gene (NM23)form small, semi-normal structures. But parent cells or cells transfectedwith the vector continued to grow in a disorganized manner. The cellsthat formed structures stopped growing, apparently because a basementmembrane, a delicate scaffolding that supports breast cells, wasdeposited - a discovery that may explain how NM23 works to limit thespread of cancer cells.In other news from the AACR meeting:* A test that measures oxidative DNA damage in white bloodcells may offer a way to detect breast cancers before they are clinicallydetectable through mammography and other means, and could identifywomen at increased risk for the disease, researchers at Wayne StateUniversity in Detroit, Mich., reported.* Genetic abnormalities in DNA extracted from tumors mayidentify women whose breast cancers are likely to recur after surgery,according to researchers at the University of California, San Franciscoand the University of Texas, San Antonio. In a study of women whosebreast cancers had not spread to the lymph nodes at the time of surgery,the researchers found a greater number of genetic abnormalities amongthose women whose breast cancers later recurred* An unusual pattern of melanomas, brain tumors, and othercancers has been discovered in the families of children treated for rarepediatric cancers at the National Cancer Institute (NCI) since 1965.NCI scientists said the results were interesting because the tumorsclustered in these families all arise from the same embryonic nervetissue, and could help in finding a gene that increases cancer risk forboth the families and the general public.* Scientists at the University of Pittsburgh Medical Centerfound that people lacking the enzyme GSTM1 may be at greater riskfor developing aggressive bladder cancer.* Researchers at Stanford University in Palo Alto, Calif.announced the genetic engineering of the bacterium Clostridiumacetobutylicum to produce an enzyme, nitoreductase, that activates acancer drug.
-- Philippa Maister
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