BAG3 protein delocalisation in prostate carcinoma.

Despite the progressive increase of early diagnosis, a subset of prostate cancers show a metastasizing and lethal course, not always predictable upon the traditional prognostic parameters. The object of this study was to investigate the role of the survival co-chaperone protein BAG3 as a new prognostic marker for prostate cancer. BAG3 was detected by immunohistochemistry in 55 specimens of surgically removed prostate carcinomas and in 15 surgical specimens of non-neoplastic prostate tissues. Results were compared with clinic-pathological data and outcome of patients and statistically evaluated. BAG3 resulted expressed in all the cases: Non-neoplastic prostate tissue showed a cytoplasmatic staining with apical reinforcement, a finding which appears consistent with the reported connection of the protein with the membrane focal cell-adhesion complexes. In prostate carcinomas, BAG3 showed a progressive decrease of the expression level from well- to low-differentiated carcinoma, coupled with the loss of polarisation of the signal in metastasizing cases. These results indicate that BAG3 intra-cytoplasmic delocalisation is a specific feature of cancer versus non-neoplastic prostate and a candidate new marker for prediction of prostate cancer invasiveness and behaviour.