Extraction of Metabolites Can Be Successfully Performed without Affecting Histopathologic Evaluation in Prostate Needle Biopsies
Cristina Magi-Galluzzi, Sara M Farzarano, Eric A Klein, Jonathan McDunn, Bruce Neri. Cleveland Clinic, Cleveland, OH; Metabolon, Inc, Durham, NC
Background: Potential application of metabolomic profiling in prostate cancer (PCA) relies on the identification of differentially accumulated metabolites in PCA compared to non-neoplastic tissue. Metabolomic profile of prostate biopsies (PBx) taken ex-vivo from radical prostatectomy (RP) and cystoprostatectomy (CP) specimens was analyzed to identify metabolites able to discriminate negative biopsies from men with and without PCA.
Design: Twelve PBx per patients were taken from 8 RP and 2 CP specimens and incubated at room temperature overnight each into a separate cryovial pre-loaded with 80% methanol/20% water. Following incubation, each PBx was removed from the solution, transferred to formalin, processed via standard histopathology methods, and stained with hematoxylin and eosin. Immunohistochemistry (IHC) for p63, CK903, racemase, and ERG was performed in 28 PBx. Methanolic solutions were analyzed for metabolites by gas chromatography/mass spectrometry and ultrahigh performance liquid chromatography/tandem mass spectrometry.
Results: Patient median age, PSA, and Body Mass Index (BMI) were 61 years, 6.24 ng/mL, and 27, respectively. All patients were White except for one CP patient who was Hispanic. Tissue was well preserved for histopathologic evaluation in all cases. PCA was found in 23 of 120 (19%) cores; high-grade prostatic intraepithelial neoplasia in 12 (10%) and atypical glands suspicious for cancer in 5 (4%). IHC confirmed preserved immunoreactivity of tissue, although the intensity of staining was weaker than positive controls in 18% of cases. Methanolic extracts were successfully analyzed for biochemical composition and 205 small molecules were measured across all major biochemical classes (amino acids, carbohydrates, lipids, nucleotides, cofactors, xenobiotics). A comparison of relative levels of compounds in PCA containing vs. non-PCA containing PBx showed significant differences for some of the compounds, such as sarcosine, kynurenine and succinylcarnitine. Of interest, levels of select steroid and polyamine catabolites were significantly higher in non-PCA than in PCA cores.
Conclusions: Microscopic diagnostic examination of tissue is important to correlate metabolomic profile with pathologic findings. This method whereby needle cores are methanol extracted prior to formalin fixation preserves tissue for successful histopathologic and IHC evaluation and provides high quality metabolite profiles for biochemical characterization of disease.
Category: Genitourinary (including renal tumors)
Monday, March 19, 2012 1:00 PM
Poster Session II # 182, Monday Afternoon