Tumor growth: lab imitating life.
While tumors tend to thrive and multiply in the human body, they often grow abnormally, if at all, in the laboratory. A technique to grow tumors three-dimensionally may provide a way to study and manipulate them in a more lifelike environment, says its developer, Robert Hoffman of the University of California at San Diego. He is already using the technique to test cancer drugs.
Fresh tumors that eventually degrade, colonies grown from a single cell and "immortalized" cell lines that develop different characteristics from their forebears are the conventional laboratory versions of human cancers. In Hoffman's system, a piece of tumor is placed on collagen-containing gel floating in a liquid cell-culture medium.
Hoffman and his colleagues have found that the tumor cells proliferate, often growing down into the gel, and maintain their three-dimensional tissue structure, genetic makeup and other characteristics. A report on the group's work will appear in an upcoming PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES.
So far, Hoffman's laboratory has a success rate of about 75 percent from 17 types of human cancers. That number "is really quite extraordinary," says Philip Frost of the M.D. Anderson Hospital and Tumor Institute in Houston. The usual success rate for culturing tumor cells is much lower--in his lab, for example, about 1 in 23 attempts at growing renal cell cancer succeeds.
Frost's laboratory has been trying the technique for the past two months. While they are still working out the methodology, Frost has great hopes for it. "If Hoffman's right and if it's as successful as he claims, it's going to revolutionize human tumor biology," he says.
A tumor-cloning procedure in which colonies are grown from a single cell enjoyed a flurry of attention several years ago. At that time its success was low, and the process has yet to live up to its promise of providing a way to select drug regimens for individual tumors. But improvements to the procedure have brought its success rate up to 80 percent in some cases, and it is valuable for screening new drugs, says Robert Shoemaker of the National Cancer Institute's Frederick (Md.) Cancer Research Facility, who is supervising three tumor-cloning projects.
Hoffman, however, maintains that cloned tumor cells will never adequately represent the tumor itself. "Since we know almost every tumore is made of multiple cell types," he says, "to have a representative tumor you want to have the cell types in the same relationship as they were inside the person."
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|Date:||Feb 15, 1986|
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