This manuscript examines the utility, utilizing the Ciphergen Protein Biosystem II, to develop a fingerprint for the diagnosis of prostate cancer. The investigators compared samples from control individuals as well as those with prostate cancer. In doing so, they utilize several chip platforms on which to examine the resulting protein peaks. In summary, these studies find a peak pattern that is able to distinguish the individuals with prostate cancer from those without the disease. This work agrees with the earlier work from Dr. John Semmes at Eastern Virginia Medical School utilizing larger sample sets. The only difference between these two studies is that the resulting patterns of expression appear to be different. This represents one of the limitations of these studies secondly, the Ciphergen instrument utilized here, has been shown to not be consistent from machine to machine and if not reproducible on running from institution to institution. Therefore, while there may be a peak signature that is able to distinguish most of the cases of prostate cancer from those without the disease, it is not clear that this same signature would be found if the samples are run in another instrument or institution. An additional limitation to these studies is that this instrument typically analyzing very small molecular weight proteins, that are proteolytic products. In prostate cancer, it is known that protease activity is different than in normal prostate. This is, in fact, reflective in the sample set that they used which have different PSA levels in the controls in comparison to those with prostate cancer. One reason alone for this difference in protein expression may be the fact that PSA, a protease, is found at higher levels in the cancer cases and therefore, may result in the proteolytic products observed in this analysis. The final limitation for this study is the fact that the end result of this work is just a protein profile. It is difficult, if not impossible, to take this to the next step of identifying what these peaks might be in developing more standard methods to validate the protein changes which are occurring in the prostate cancer. This is clearly an exciting time in the development of proteomic approaches and their application to urologic diseases. It is clear, that by using some of the latest instruments, we are making significant advances towards developing profiles which can define both disease states as well as response to therapies and prognosis.

Full Text |