Potentially Revolutionary Approach to Immunization Uses DNA Vaccine

PNAS Oct. 11, 1994- page 2

PCR-BASED ASSAY FOR CANCER CELLS MAY IMPACT PRESENT SURGICAL PRACTICE
A new PCR-based assay that detects genetic instability may have broad implications for more rapid and
simple early cancer screening. Alterations in tandem repeat DNA sequences, also known as
microsatellites, have previously been detected in inherited disorders including Huntington's disease and
hereditary colorectal carcinoma. Investigators write in an article beginning on Page 9871 that
appropriately selected microsatellite loci are commonly altered in many cancers and can serve as clonal
markers for their detection. The researchers examined microsatellite alterations in tumor tissue taken
from head and neck, bladder, and lung patients and found identical alterations in those patients' urine,
sputum, and surgical margins which pathologists had previously pronounced negative for tumor cells.
As most cancer cells are expected to show extensive alterations of microsatellites, this technique should
detect one cancer cell among 200 to 1000 normal cells. The authors demonstrated the feasibility of
using "multiplex PCR," which incorporates a combination of microsatellite markers in a single PCR
reaction, as a broad screen to identify a high fraction of cancers simultaneously. For further
information, contact David Sidransky of the Johns Hopkins University School of Medicine's
Department of Otolaryngology, Baltimore; tel. [phone].
Other article of interest:
Researchers have produced an animal model for Tay-Sachs by disrupting the HEXA gene in mouse
embryonic stem cells; the resulting mice have the biochemical and neuropathological features of TaySachs disease, for which there is at present no effective treatment, and will allow evaluation of
potential therapeutic strategies such as enzyme replacement and gene transfer. The article begins on
Page 9975. For further information, contact Richard Proia of the National Institute of Diabetes and
Digestive and Kidney Diseases, Bethesda; tel. [phone].

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