Purpose
Inhibitors of monoamine oxidase A (MAOA), a mitochondrial enzyme that degrades neurotransmitters including serotonin and norepinephrine, are commonly used to treat neurological conditions including depression. Recently, we and others identified high expression of MAOA in normal basal prostatic epithelium and high-grade primary prostate cancer (PCa). In contrast, MAOA is low in normal secretory prostatic epithelium and low-grade PCa. An irreversible inhibitor of MAOA, clorgyline, induced secretory differentiation in primary cultures of normal basal epithelial cells and high-grade PCa. Furthermore, clorgyline inhibited several oncogenic pathways in PCa cells, suggesting clinical value of MAOA inhibitors as a pro-differentiation and anti-oncogenic therapy for high-risk PCa. Here, we extended our studies to a model of advanced PCa, VCaP cells, which were derived from castration-resistant metastatic PCa and express a high level of MAOA.
Methods
Growth of VCaP cells in the presence or absence of clorgyline was evaluated in vitro and in vivo. Gene expression changes in response to clorgyline were determined by microarray and validated by quantitative real-time polymerase chain reaction.
Results
Treatment with clorgyline in vitro inhibited growth and altered the transcriptional pattern of VCaP cells in a manner consistent with the pro-differentiation and anti-oncogenic effects seen in treated primary PCa cells. Src, beta-catenin, and MAPK oncogenic pathways, implicated in androgen-independent growth and metastasis, were significantly downregulated. Clorgyline treatment of mice bearing VCaP xenografts slowed tumor growth and induced transcriptome changes similar to those noted in vitro.
Conclusion
Our results support the possibility that anti-depressant drugs that target MAOA might find a new application in treating PCa.
Although a high level of evidence is currently missing to draw any strong conclusion, published clinical series show that in select patients salvage treatment directed to nodal recurrence could lead to good oncologic outcomes. Although the optimal timing of androgen deprivation therapy in this setting is still unknown, such an approach could delay time to systemic treatment with an acceptable safety profile. Future prospective trials are awaited to better clarify this potential impact on well-defined endpoints.
Histological subtyping of pRCC has no impact on oncologic outcomes after nephron sparing surgery. In this selected population of pRCC tumors, we found that tumor stage is the only prognostic factor for cancer-free survival.
Background: Monoamine oxidase A (MAO-A), a mitochondrial enzyme that degrades monoamines including neurotransmitters, is highly expressed in basal cells of the normal human prostatic epithelium and in poorly differentiated (Gleason grades 4 and 5), aggressive prostate cancer (PCa). Clorgyline, an MAO-A inhibitor, induces secretory differentiation of normal prostate cells. We examined the effects of clorgyline on the transcriptional program of epithelial cells cultured from high grade PCa (E-CA).
CCPRCC is now a well-characterized entity. This tumour is an indolent and very low-grade neoplasm. Here we report the first study, to our knowledge, demonstrating the overexpression of cyclin D1 immunostaining by this tumour.
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