For cancer cells, genetics alone is poor indicator for dru...( BOSTON Mass. (April 12 2009) In cer...)

BOSTON, Mass. (April 12, 2009) In certain respects, cells are less like machines and more like people. True, they have lots of components, but they also have lots of personality. For example, when specific groups of people are studied in aggregate (conservatives, liberals, atheists, evangelicals), they appear to be fairly uniform and predictable. But when looked at one person at a time, individuals often break the preconceptions.

Same with cells.

Researchers tend to identify characteristics of particular cells by looking at millions at a time. As a result, they'll find that, say, "group A" responds very well to a particular cancer treatment, whereas "group B" does not. They will then often compare group A to group B to find out why.

But often ignored is that not every cell in either group behaves in ways that the aggregate indicates. In a group of cells shown to be vulnerable to a particular cancer treatment, perhaps 10 percent resist it while 90 percent succumb. While researchers have offered various explanations for this, few have studied it.

Now a group of scientists in the lab of Harvard Medical School Professor of Systems Biology Peter Sorger have studied such "outlier" cells in the context of a new and highly touted cancer drug. They have found that vastly disparate reactions occur within genetically homogeneous cell groups. These discrepancies result from protein levels that vary from cell to cell, even among cells that are identical genetic twins. What's more, these protein levels and their subsequent traits can be passed down to daughter cellsa heritability that has nothing to do with genetics.

"Genetics are permanently heritable, while these protein levels are temporarily heritable," says Sorger. "But this temporary inheritance can make all the difference in the world when it comes to the effectiveness of certain medications."

These findings are published April 12 online in Nature. '/>"/>