High SPDEF may identify patients who will have a prolonged response to androgen deprivation therapy.

BACKGROUND: Due to the indolent nature of prostate cancer, new prognostic measures are needed to identify patients with life threatening disease. SAM pointed domain-containing Ets transcription factor (SPDEF) has been associated with good prognosis and demonstrates an intimate relationship with the androgen receptor (AR), however its role in prostate cancer progression remains unclear. METHODS: A tissue microarray constructed from cores of 713 consecutive radical prostatectomy specimens were immunohistochemically stained for SPDEF and correlated with progression free and metastatic free survival. In vitro studies assessed growth rate, migration, and sensitivity to bicalutamide to explore mechanisms behind the tissue microarray observations. RESULTS: Patients with high SPDEF demonstrate longer metastases free survival after receiving the standard of care (HR = 9.80, P = 0.006). SPDEF expression corresponded with bicalutamide growth inhibition and apoptosis induction in all cell lines studied. In addition, a feedforward loop of AR-SPEF expression regulation is observed. CONCLUSIONS: SPDEF may be clinically useful to identify patients who will have extended benefits from androgen deprivation therapy. In vitro observations suggest SPDEF mediates initial sensitivity to androgen deprivation therapy through both AR regulation and downstream events.

Transcriptional profiling of degraded RNA in cryopreserved and fixed tissue samples obtained at autopsy.

BACKGROUND: Traditional multiplexed gene expression methods require well preserved, intact RNA. Such specimens are difficult to acquire in clinical practice where formalin fixation is the standard procedure for processing tissue. Even when special handling methods are used to obtain frozen tissue, there may be RNA degradation; for example autopsy samples where degradation occurs both pre-mortem and during the interval between death and cryopreservation. Although specimens with partially degraded RNA can be analyzed by qRT-PCR, these analyses can only be done individually or at low levels of multiplexing and are laborious and expensive to run for large numbers of RNA targets. METHODS: We evaluated the ability of the cDNA-mediated Annealing, Selection, extension, and Ligation (DASL) assay to provide highly multiplexed analyses of cryopreserved and formalin fixed, paraffin embedded (FFPE) tissues obtained at autopsy. Each assay provides data on 1536 targets, and can be performed on specimens with RNA fragments as small as 60 bp. RESULTS: The DASL performed accurately and consistently with cryopreserved RNA obtained at autopsy as well as with RNA extracted from formalin-fixed paraffin embedded tissue that had a cryopreserved mirror image specimen with high quality RNA. In FFPE tissue where the cryopreserved mirror image specimen was of low quality the assay performed reproducibly on some but not all specimens. CONCLUSION: The DASL assay provides reproducible results from cryopreserved specimens and many FFPE specimens obtained at autopsy. Gene expression analyses of these specimens may be especially valuable for the study of non-cancer endpoints, where surgical specimens are rarely available.