[Alpha-defensins as markers for colon cancer]
Full text freebie, hot off the press:
biomedcentral.com
These defensins are part of the immune system's armament, and as such are not terribly specific to colon cancer or any cancer. Their elevation in the serum of colon cancer patients is minimal, and again, could be due to something else. Nevertheless, as the authors point out, they could be used as markers in conjunction with other markers.
The authors observe that these defensins bind to various common molecules in serum, such as albumin. This adds to the "growing realization that common plasma proteins may carry disease specific peptides and therefore should not be ignored in biomarker research." Indeed, we've already seen that mentioned by Liotta and Petricoin, among others. Unfortunately, that means some extra steps that one would not undertake in a clinical diagnostic lab, i.e. another step of chromatography, MALDI-TOF, and subsequent analysis.
They also note that different chips give the best signals for tissue versus serum samples. They don't really say why, but the above-mentioned binding to plasma proteins seems the obvious reason to me.
So in terms of finding a great set of diagnostic markers, this study is a failure, but it does show the promise of SELDI in finding them, and shows in detail how that process works.
Cheers, Tuck |
