Fig. 4.

Inhibition of monoamine oxidase A (MAO-A) induces AR expression in E-PZ cells. (A) AR transcript levels determined by semi-quantitative RT-PCR are increased in cells treated with clorgyline, an irreversible MAO-A inhibitor, and androgen compared with control cells. The treatment conditions are shown on top of each lane (VRT = 1,25-dihydroxyvitamin D₃ [10 nM], all-trans retinoic acid [1 µM] and TGF-β1 [1 ng/ml]). Duplicate samples are analyzed for each condition. TBP transcript level in each sample is examined as an internal control for experimental variations. (B) AR protein in nuclear extracts is detectable by Western blotting analysis in clorgyline-treated but not control or pargyline (a preferential MAO-B inhibitor)-treated cells, and AR is further increased in the presence of androgen. GAPDH levels are determined as an internal control for experimental variation. (C) MAO-A enzymatic activity is inhibited by clorgyline in E-PZ cells. Control cells are grown in standard medium. Experimental cells are treated with VRT and clorgyline (1 µM) for 16hr. (D), (F), (H) are immunofluorescent staining of AR protein showing no detectable AR in control cells (D), faint AR signal in clorgyline-treated cells (F), and strong signal in clorgyline- and androgen-treated cells (H). (E), (G), (I) are DAPI staining showing the nuclei of the same cells in (D), (F), (H), respectively. The magnification for (C-H) is × 200. For all images, the size bar is 100µM. TGF-β1, transforming growth factor; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; AR, androgen receptor; TBP, TATA box binding protein.