The influence of inflammation in the search of discriminatory biomarkers for prostate cancer: a proteomic study

background: Despite the improvements in clinical and surgical practice, prostate cancer (PCa) remains one of the most widespread cancer in male. The serum marker currently used for the diagnosis of PCa is the prostate-specific antigen (PSA), but its increase does not discriminate benign prostatic hyperplasia (BPH) from PCa. In our study, we investigated the serum protein expression of BPH compared to PCa, in order to identify by Surface Enhanced Laser Desorption/Ionization - Time of Flight - Mass Spectrometry (SELDI-ToF-MS) analysis distinctive protein profiles able to unquestionably discriminate patients with a benign prostate condition from those with a malignant situation. Moreover, we considered these conditions focusing on the co-existence of inflammation. Methods: Patients with clinical suspect of PCa (PSA elevation and/or palpable mass at digital rectal exploration) and candidates for trans-rectal ultrasound guided prostate biopsy were enrolled. The analysis of protein profile of 30 patients with PCa and 30 subjects with BPH was carried out. All histological specimens were examined in order to graduate and classify the tumor and to recognize the BPH condition and presence of inflammation, that was classed in chronic and acute and then graduated in mild, moderate and severe. Serum was depleted of the 6 high-abundance proteins by immunoaffinity chromatography prior to SELDI-ToF-MS analysis. Results: The comparison between protein spectra from PCa and BPH considering the inflammation parameter and excluding samples with moderate and/or severe inflammation, identified 17 differentially expressed protein peaks using H50 ProteinChip Array.The analysis of protein profile in presence of inflammation showed different protein peaks in the two groups, some of which overlapped with those found also in the comparison between PCa and BPH in absence of inflammation. Conclusions: The inflammation seems to lead a crucial contribution in the protein profile assessments of these conditions. On the basis of our results, we believe that certain different protein peaks could be reasonably associated to inflammation rather than to cancer. Therefore, inflammation might be a confounding parameter in the search of specific biomarkers to discriminate PCa from BPH.