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'lizbeth
I just don't know what to think about DiaTech. A number of years ago I wrote to Gary about why they posted on their website that the DISC and MTT assays (two of a number of "cell-death" assays) were "cell-growth" assays. They are "cell-death" assays, not "cell-growth" assays. They never corrected this misinformation. I let it go. Now I read on this press release that they claim they are the only commercial reference laboratory in the U.S. that works exclusively with "live" cancer cells and the only ones with "expertise and technology" to measure "drug sensitivity" of specific cancer cells. Why the deceptive advertising? They are not the only one in the U.S. I just wanted to point that out that misinformation.
Assays use an endpoint, which is a point of termination (end result). Four "cell-death" assays are DISC, MTT, ATP and Caspase 3/7. The DiaTech MiCK uses only one caspase assay. This is the only endpoint they use. I pointed out that while apoptosis represents an important mechanism of programmed cell death, it is only one of several cell-death pathways. There is apoptotic and non-apoptotic programmed cell-death pathways. Caspase measures only the one type. In order to measure all types of pathways, you need two or more of the "cell-death" endpoints (DISC, MTT, ATP and Caspase). Relying on only one endpoint is not very accurate!
Labs that focus on measurements of caspase activation can only measure apoptotic cell-death. Now that's important in hematologic cancers and lymphomas, but it does not represent the mechanism of cell-death in all solid tumors (like breast cancer). Laboratories that utilize functional cytometric profiling use combined metabolic (cell metabolism) and morphologic (structure) endpoints. A lot more "accurate" in measuring all manner of apoptosis (cell death).
The difference between cell-growth and cell-death assays is that cell-growth assays look to see which drugs inhibited the cancer cells' growth (cell-growth), while cell-death assays look to see which drugs actively kills the tumor cells (cell-death). Cancer doesn't grow faster than other cells, it just dies slower. Cell-death assay technology connects drugs to patients by what "kills" their cells, not by what "slows" them down. And they certainly don't just measure what genes or proteins 'hang' out with the cells. They measure the entire genome.
I hope this gives you some better understanding. Cancer is many things, but "simple" is not one of them. I would look for an assay that is a lot more accurate than just one cell-death endpoint and an assay that is more accurate than one that chases after what a cell 'hangs" with.
Greg
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