br aggressiveness Measurement of miR
aggressiveness.17,18,20,21 Measurement of miR-182 by RT- qPCR in prostate tumor specimens, not microdissected, have found either no significant association21,47 or a positive
association of miR-182 expression with recurrence.39 In the study by Casanova-Salas et al,39 medium, but not high levels of miR-182 were significantly associated with recurrence, which is somewhat supported by our findings. The discrepancies between our results and previous studies
may be attributable to differing measurement methods.21,39,47 Our findings using ISH and LCM-collected
prostate epithelium remove stromal contamination as a bias that is unavoidable in the whole tissues used in the other studies. In addition, the cancer miR-182 levels were normalized to benign levels within each patient for the analysis, which is in Micafungin to the other studies of miR-182 in recurrence that did not consider benign tissues. It is plausible that the change in expression of miR-182 in PCa per patient is more physiologically important than its standalone expression level.
Overall, our results suggest that the function of miR-182 changes during PCa, possibly promoting early oncogenic changes but becoming protective or selected against in high-risk PCa. A limitation to our study is the lack of matched metastases in which to determine the levels in advanced stages of disease. A previous study that supported the hy-pothesis of a dual role of miR-182 in PCa found that miR-182 promoted resistance to apoptosis on growth factor withdrawal in an immortalized primary prostate cell line but reversed the epithelial to mesenchymal transition that is observed in that cell line.51 This expression paradox is not unusual in PCa. a-Methylacyl CoA racemase is also up-
Figure 4 Benign epithelial expression of miR-182 is lower in prostate that contains high Gleason grade and in African American (AA) men. A: The expression of miR-182 in benign epithelium trends toward being higher in patients with lower Gleason grade tumors. Normalization for quantitative RT-PCR was performed using the mean expression of RNU44, RNU48, and RNU66 Kruskal-Wallis test, not significant. B: miR-182 expression in patients by ancestry were designated by single-nucleotide polymorphism (SNP) analysis showing >50% West African ancestry (AA) or >80% European ancestry (EA), respectively. SNP data were not available for two patients, and self-reported race was used (U-test). C and D: Predicted miR-182 target genes are enriched for genes with higher expres-sion in prostate cancer (PCa) tumors from AA men than in PCa
tumors from EA men from the gene sets in the studies by Wallace et al38 (C) and from Powell et al44 (D). E: Proposed model of miR-
182 expression patterns at different disease stages in patients at high risk and low risk for PCa based on the data in this study. The expression of miR-182 in metastatic PCa was not measured in this study, but because miR-182 was negatively correlated with genes expressed in metastasis in prostate epithelium (Figure 3D), it is hypothesized to decrease. Data are expressed as means SD. n Z 14 (A, Gleason 3þ 3/2); n Z 15 (A, Gleason 3þ 4/5); n Z 6 (A, Gleason 4þ 3/4); n Z 22 (B, AA men); n Z 16 (B, EA mean). *P < 0.05, ****P < 0.0001. BCR, biochemical recurrence; HGPIN, high-grade prostatic intra-epithelial neoplasia; LCM, laser-captured microdissected; NES, normalized enrichment score; RQ, relative quantity.
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regulated in PCa and may functionally promote PCa growth,52 but lower levels of a-methylacyl CoA racemase are associated with more advanced disease.53,54 In addition, androgen receptor is a well-established driver of prostate proliferation, but higher expression of several androgen re-ceptor target genes predicts indolent disease in the Oncotype DX genomic assay.55 miR-182 is regulated by androgen
receptor in lymph node carcinoma of the prostate PCa cells,18,56 suggesting that miR-182 levels may be a pas- senger change that results directly or indirectly from cross-talk with androgen signaling. However, no correlation was observed between miR-182 expression and the expression of transcripts for AR, AR-target KLK3 (PSA), or AMACR in benign prostate epithelium in our study (Supplemental Table S1). Potentially of interest, the transcript for gluco-corticoid receptor, which is down-regulated in primary PCa tumors and re-expressed in metastases, is strongly nega-tively correlated with miR-182 in our array data set (NR3C1,
r Z 0.64, P Z 0.002).42 Glucocorticoid receptor may promote AR independence of advanced PCa, and biochemical relapse patients with high expression of