title: Decreased alpha-methylacyl CoA racemase expression in localized prostate cancer is associated with an increased rate of biochemical recurrence and cancer-specific death.
abstract: Alpha-methylacyl CoA racemase (AMACR) is overexpressed in prostate cancer relative to benign prostatic tissue. AMACR expression is highest in localized prostate cancer and decreases in metastatic prostate cancer. Herein, we explored the use of AMACR as a biomarker for aggressive prostate cancer. AMACR protein expression was determined by immunohistochemistry using an image analysis system on two localized prostate cancer cohorts consisting of 204 men treated by radical prostatectomy and 188 men followed expectantly. The end points for the cohorts were time to prostate-specific antigen (PSA) failure (i.e., elevation >0.2 ng/mL) and time to prostate cancer death in the watchful waiting cohort. Using a regression tree method, optimal AMACR protein expression cut-points were determined to best differentiate prostate cancer outcome in each of the cohorts separately. Cox proportional hazard models were then employed to examine the effect of the AMACR cut-point on prostate cancer outcome, and adjusted for clinical variables. Lower AMACR tissue expression was associated with worse prostate cancer outcome, independent of clinical variables (hazard ratio, 3.7 for PSA failure; P = 0.018; hazard ratio, 4.1 for prostate cancer death, P = 0.0006). Among those with both low AMACR expression and high Gleason score, the risk of prostate cancer death was 18-fold higher (P = 0.006). The AMACR cut-point developed using prostate cancer-specific death as the end point predicted PSA failures independent of Gleason score, PSA, and margin status. This is the first study to show that AMACR expression is significantly associated with prostate cancer progression and suggests that not all surrogate end points may be optimal to define biomarkers of aggressive prostate cancer.
authors.affiliation: Department of Pathology (Amory 3-195), Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, Massachusetts 02115, USA. marubin@partners.org
authors.forename: Mark A
authors.initials: MA
authors.lastname: Rubin
authors.forename: Tarek A
authors.initials: TA
authors.lastname: Bismar
authors.forename: Ove
authors.initials: O
authors.lastname: Andrén
authors.forename: Lorelei
authors.initials: L
authors.lastname: Mucci
authors.forename: Robert
authors.initials: R
authors.lastname: Kim
authors.forename: Ronglai
authors.initials: R
authors.lastname: Shen
authors.forename: Debashis
authors.initials: D
authors.lastname: Ghosh
authors.forename: John T
authors.initials: JT
authors.lastname: Wei
authors.forename: Arul M
authors.initials: AM
authors.lastname: Chinnaiyan
authors.forename: Hans-Olov
authors.initials: HO
authors.lastname: Adami
authors.forename: Philip W
authors.initials: PW
authors.lastname: Kantoff
authors.forename: Jan-Erik
authors.initials: JE
authors.lastname: Johansson
mesh_terms: D014408:Biomarkers, Tumor / Q000097:blood*; D015331:Cohort Studies; D018450:Disease Progression; D020869:Gene Expression Profiling; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D019998:Racemases and Epimerases / Q000096:biosynthesis*; D016019:Survival Analysis
chemical_list: D014408:Biomarkers, Tumor; D019998:Racemases and Epimerases; C108352:alpha-methylacyl-CoA racemase