title: alpha-Methylacyl-CoA racemase: expression levels of this novel cancer biomarker depend on tumor differentiation.
abstract: alpha-Methylacyl-CoA racemase (AMACR) has previously been shown to be a highly sensitive marker for colorectal and clinically localized prostate cancer (PCa). However, AMACR expression was down-regulated at the transcript and protein level in hormone-refractory metastatic PCa, suggesting a hormone-dependent expression of AMACR. To further explore the hypothesis that AMACR is hormone regulated and plays a role in PCa progression AMACR protein expression was characterized in a broad range of PCa samples treated with variable amounts and lengths of exogenous anti-androgens. Analysis included standard slides and high-density tissue microarrays. AMACR protein expression was significantly increased in localized hormone-naive PCa as compared to benign (P < 0.001). Mean AMACR expression was lower in tissue samples from patients who had received neoadjuvant hormone treatment but still higher compared to hormone-refractory metastases. The hormone-sensitive tumor cell line, LNCaP, demonstrated stronger AMACR expression by Western blot analysis than the poorly differentiated cell lines DU-145 and PC-3. AMACR protein expression in cells after exposure to anti-androgen treatment was unchanged, whereas prostate-specific antigen, known to be androgen-regulated, demonstrated decreased protein expression. Surprisingly, this data suggests that AMACR expression is not regulated by androgens. Examination of colorectal cancer, which is not hormone regulated, demonstrated high levels of AMACR expression in well to moderately differentiated tumors and weak expression in anaplastic colorectal cancers. Taken together, these data suggest that AMACR expression is not hormone-dependent but may in fact be a marker of tumor differentiation.
authors.affiliation: Department of Pathology, University of Michigan Medical School, Ann Arbor 48109-0602, USA.
authors.forename: Rainer
authors.initials: R
authors.lastname: Kuefer
authors.forename: Sooryanarayana
authors.initials: S
authors.lastname: Varambally
authors.forename: Ming
authors.initials: M
authors.lastname: Zhou
authors.forename: Peter C
authors.initials: PC
authors.lastname: Lucas
authors.forename: Martin
authors.initials: M
authors.lastname: Loeffler
authors.forename: Hubertus
authors.initials: H
authors.lastname: Wolter
authors.forename: Torsten
authors.initials: T
authors.lastname: Mattfeldt
authors.forename: Richard E
authors.initials: RE
authors.lastname: Hautmann
authors.forename: Juergen E
authors.initials: JE
authors.lastname: Gschwend
authors.forename: Terrence R
authors.initials: TR
authors.lastname: Barrette
authors.forename: Rodney L
authors.initials: RL
authors.lastname: Dunn
authors.forename: Arul M
authors.initials: AM
authors.lastname: Chinnaiyan
authors.forename: Mark A
authors.initials: MA
authors.lastname: Rubin
mesh_terms: D014408:Biomarkers, Tumor; D002454:Cell Differentiation / Q000235:genetics; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D019998:Racemases and Epimerases / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D014408:Biomarkers, Tumor; D019998:Racemases and Epimerases; C108352:alpha-methylacyl-CoA racemase