Original Article Influence of hypoxia induced by minimally invasive prostatectomy on gene expression: implications for biomarker analysis
Heidi S. Erickson, John W. Josephson, Manish Vira, Paul S. Albert, John W. Gillespie, Jaime Rodriguez-Canales, Peter A. Pinto, Rodrigo F. Chuaqui, Michael R. Emmert-Buck, Jonathan A. Coleman
Department of Thoracic/Head and Neck Medical Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030; Pathogenetics Unit, Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892; Urologic Oncology Branch, National Cancer Institute, National Institutes of Health 20892; The Smith Institute for Urology, North Shore Long Island Jewish Health System, New Hyde Park, NY 11040; Biometric Research Branch, Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, 20852; SAIC-Frederick, Inc., National Cancer Institute at Frederick, Frederick, Maryland 21702; Memorial Sloan-Kettering Cancer Center, Department of Urology, New York, New York, 10021
Received April 1, 2010; accepted April 2, 2010; available online April 10, 2010
Abstract: Handling and processing of clinical specimens during and after surgical resection may significantly skew the molecular data obtained from analysis of those samples. Minimally invasive prostatectomy was used as a model to specifically study effects of surgical ischemia on gene expression in human clinical samples. Normal prostatic urethra cup biopsies were procured from 12 patients at three time points during laparoscopic radical prostatectomy. Homogeneous cells (stroma and epithelium) were microdissected. Transcript analysis of oxygen-dependent, oxygen-independent, and control class genes was performed using quantitative RT-PCR. Data were analyzed by relative quantitation and two-sided t-test. Patient demographic and time covariates were fit by a linear mixed model. Vascular-derived endothelial growth factor (VEGF) was the only transcript that significantly changed across the three time points (T0 to T1 to T2) (P < 0.01) during laparoscopic surgery. VEGF, an oxygen-dependent gene, showed significant expression alterations across three time points in epithelium (p=0.008), but not in stroma (p=0.66). Expression levels of VHL, STAT5B, and CYPA showed significant changes at the p<0.05 level in the stroma only. Effects of age, PSA, prostate size, Gleason score surgery type, total surgery time, total ischemia time, and estimated blood loss on VEGF expression over time were not significant at the p<0.01 level. Therefore, surgical manipulation and tissue processing methods need to be taken into account when assessing prostatic biomarkers; however resection does not dramatically alter mRNA profiles in prostate specimens.(AJTR1003006).
Address all correspondence to: Heidi S. Erickson, PhD Department of Thoracic/Head and Neck Medical Oncology The University of Texas M.D. Anderson Cancer Center Houston, Texas 77030. E-mail: HSErickson@mdanderson.org