Metabolomics and histology on exactly the same ex vivo prostate biopsy.

Abstract

166 Background: Histopathology is the standard method for diagnosis and histological grading and staging of cancer. Molecular biomarkers are associated with cancer aggressiveness. One drawback to some molecular studies is that the portion of the tissue to be analyzed is processed in a manner that is destructive to the tissue. We present here a new method for performing analysis of small molecule biomarkers and histology in exactly the same biopsy tissue. The process, molecular Preservation by Extraction and Fixation (mPREF), allows traditional histological examination to be combined with qualitative and quantitative analysis of small molecule biomarkers. Methods: 18 gauge core biopsies were obtained ex vivo from prostatectomy specimens. One core biopsy/specimen container was immersed in aqueous alcohol. After 12-24 hrs, biopsies were transferred to UMFIX, and the original alcohol retained. Histologic sections of biopsies were stained by routine methods and the immunohistochemical (IHC) stain, PIN4. Small molecular weight molecules in the retained alcohol were examined by a mass spectrometry-based method. Results: Light Microscopy: Tumor and grade were evaluable and IHC for PIN4 performed well. Metabolomics of Retained Alcohol: From a single core biopsy, 260 named biochemical compounds and their relative concentrations WERE detected. 83 were different between the cancer and non-cancer biopsy extracts (p< .05). 18 of the 20 common amino acids, and a number of long chain fatty acids and phospholipids were increased. Highest fold changes, 4- to 6-fold, were observed in cysteine, dihomo-linoleate, docosapentaenoate, N-acetylaspartate, N-acetylglucosamine, uracil, xanthine, and 1-stearoylglycerophosphoinositol. A sub-set of candidate biomarkers were differentially expressed in pT3 vs pT2 disease. Conclusions: MPREF allows for both histology and detection of small molecules in exactly the same tissue. The results suggest a higher metabolic state in cancer as compared with non-cancer containing biopsy tissues. Differential expression of small molecules from pT2 vs pT3 disease suggests that quantitative prognostic molecular and histologic data can be obtained from a single core biopsy.