The molecules that surround a cell play a crucial role in altering the packaging of its genome, opening it up to the machinery that allows genes to be expressed, or closing it down, according to a study published in the April issue of the American Journal of Pathology.
An editorial in the same issue of the journal says the study represents what it calls a paradigm shift in our understanding of how malignant cells operate. The findings are expected to yield new diagnostic and therapeutic tools in the battle against cancer.
Initial experiments at UIC found that the genetic material of cancer cells is knotted-up so that sections of DNA are highly protected from outside interference, unlike the DNA of healthy tissue.
An enzyme that snips DNA at certain sequences that recur throughout the genome thoroughly chewed up the DNA from normal cells. In contrast, the enzyme only partially broke up the DNA from less aggressive tumors, and it barely touched the DNA from aggressive cancers like melanoma.
"In invasive cancers, segments of DNA are so twisted and compacted that the enzyme can't get access," said Andrew Maniotis, assistant professor of pathology and lead author of the study.
"We tested a range of cells -- from connective tissue, breast tissue, the kidney and the colon -- as well as biopsy tissue. The results were always the same," added Robert Folberg, head of pathology and a co-author of the paper. "The more invasive the cancer, the more resistant its DNA was to the enzyme."
But the question was why.
The answer lies in the cells' immediate environment, called the extracellular matrix, a rich mix of molecules once thought to be biologically inert.