Evidence Found for viral Basis of Tumors
Harvard researchers at the Dana-Farber Cancer Institute have found evidence of a viral basis for brain tumors, according to a recent study published in the New England Journal of Medicine.
Associate Professor of Pediatrics Dr. Robert L. Garcea '70 reported last week in the Journal that he and colleagues at the Institute have correlated DNA sequences in pediatric brain tumors and in simian virus 40 (SV40).
SV40 is known to lead to tumors in certain animals, including humans. The rare tumors associated with the virus usually appear before two years of age in humans, and doctors often have difficulty treating them because they lie deep within the brain, in an area known as the choriod plexus, which manufactures cerebro-spinal fluid.
Garcea said in an interview yesterday that past research has implicated a protein, called a t-antigen, in all choriod plexus tumors in laboratory animals. The t-antigen has been shown to result from the expression of an SV40 DNA sequence.
Past research by other doctors has linked the activity or antigens, foreign substances against which the body's immune system acts, to the expression of DNA sequences called oncogenes, which eventually lead to cancer.
The pediatrician said that early use of transgenic mice, into whose gametes the sequence coding for the t-antigen was inserted, led to the conclusion that SV40 was involved when all of the animals developed the tumors.
Eventually, using DNA probing techniques on 31 pediatric tumor samples, Garcea showed that a large fraction of the samples reacted with the sequence for the SV40 t-antigen.
Eventually, Garcea said, he hopes to verify the finding with more samples. However, because of the rarity of the disease--only a few hundred cases are diagnosed each year in the U.S.--it will be difficult to locate enough samples for such a study, he said.
But, Garcea said, the study's publication may bring more such cancer victims out of the woodwork for further projects. "We want to accumulate as many samples as possible," he said. "If the finding holds up, the next logical stop is a histological study of fetal serum."
Garcea emphasized that further study on the tumors was necessary.
"I think people are very skeptical about viral links to cancer," he said. "It's a controversial area."
Fruit Fly Protein Is Clue to Embryo Growth
Scientists may be one step closer to unravelling the complex path of the human embryo's development form the joining of sperm and egg to birth, thanks to a team of researchers at Boston Children's Hospital.
This month's issue of Nature Genetics features an study by Fikes Professor of Pediatric Medicine Dr. stuart H. Orkin and several colleagues, who have deduced remarkable similarities in amino acid sequence between a human gene expression regulator, CCAAT displacement protein (CDP), and the cut protein, an important regulator of cell differentiation in fruit flies (Drosophila).