Prognostic value of alpha-methyl CoA racemase (AMACR) expression in renal cell carcinoma.
OBJECTIVE
Alpha-methyl CoA racemase (AMACR) is used as an immunohistochemical marker for renal cell carcinoma (RCC) subtyping to distinguish papillary (pap) RCC. Expression of AMACR in other renal tumor subtypes is inhomogeneous, and the clinical and prognostic value of AMACR is unknown. The aim of this study was to asses AMACR protein expression in different RCC subtypes and to investigate its prognostic significance.


METHODS
Protein expression of AMACR was analyzed in 1,088 renal tumor samples, among them 809 clear cell RCC and 151 papRCC, by immunohistochemistry using tissue microarry (TMA) technique. Results were correlated with clinicopathological data and to follow-up data [overall (OS)/cancer-specific survival (CSS)].


RESULTS
Frequency of AMACR expression was significantly higher in papRCC compared to other tumor subtypes (83% vs. 15-35%, p < 0.0001). Presence of AMACR did not correlate with stage or nodal metastases in papRCC. In a dichotomized scoring (negative vs. positive expression), an inverse correlation between higher grade (p = 0.03) and presence of distant metastasis (p = 0.014) was observed in papRCC. AMACR expression correlated with the presence of nodal metastasis in ccRCC (p = 0.02). Both in ccRCC and in papRCC, OS and CSS did not correlate with the AMACR expression status.


CONCLUSIONS
The high expression in papRCC confirms AMACR to be a marker for subtype differentiation in RCC, while a missing expression in this subtype seems to be associated with negative pathological features. However, in contrast to other tumor entities, AMACR expression seems to have a limited prognostic impact in renal carcinoma, especially with regard to survival.
Department of Urology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany. c.eichelberg@uke.de
Christian
C
Eichelberg
Sarah
S
Minner
Hendrik
H
Isbarn
Eike
E
Burandt
Luigi
L
Terracciano
Holger
H
Moch
Alexandra
A
Kell
Roman
R
Heuer
Felix K
FK
Chun
Guido
G
Sauter
Margit
M
Fisch
Pierre
P
Tennstedt
D014408:Biomarkers, Tumor / Q000096:biosynthesis* / Q000235:genetics; D002292:Carcinoma, Renal Cell / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism* / Q000401:mortality; D015331:Cohort Studies; D005500:Follow-Up Studies; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D053208:Kaplan-Meier Estimate; D007680:Kidney Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism* / Q000401:mortality; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D011379:Prognosis; D019998:Racemases and Epimerases / Q000096:biosynthesis* / Q000235:genetics; D012189:Retrospective Studies; D015996:Survival Rate
D014408:Biomarkers, Tumor; D019998:Racemases and Epimerases; C108352:alpha-methylacyl-CoA racemase